Enclosed here find 27 pages of scientific abstracts concerning carbohydrates
and all types of exercise.
Best way to read these is to go to the bottom of the paper and read the
conclusions, then, if you want, start at the top for the particulars.
Those supporters of fat as an athletic advantage, please match, or carbs as a
disadvantage in human or equine performance, please provide similar
documentation. That is, papers dealing with exercise performance in man or
equine.
ti
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Authors RB Kreider, R Klesges, K Harmon, P Grindstaff, L Ramsey, D Bullen=
, L Wood, YH Li, A Almada
Title Effects of Ingesting Supplements Designed to Promote Lean Tissue Ac=
cretion on Body-Composition During Resistance Training
Full source International Journal of Sport Nutrition, 1996, Vol 6, Iss 3,=
pp 234-246
Author keywords Carbohydrate; Protein; Chromium; Boron; Creatine; Taurine=
KeyWords Plus X-RAY ABSORPTIOMETRY; CREATINE SUPPLEMENTATION; CHROMIUM SU=
PPLEMENTATION; PROTEIN-SYNTHESIS; SKELETAL-MUSCLE; INSULIN; TAURINE; HYDR=
ATION; GLUTAMINE; EXERCISE
TGA/Book No. VD611
Discipline Sports Science & Medicine
Document type Article
Language English
Address Kreider RB, Memphis Univ, Dept Human Movement Sci & Educ, Exercis=
e & Sport Sci Lab, Memphis,TN 38152 USA
ISBN/ISSN 1050-1606
Publisher Human Kinetics Publ Inc, 1607 N Market St, Box 5076, Champaign,=
IL 61820-5076
Abstract This study examined the effects of ingesting nutritional supplem=
ents designed to promote lean tissue accretion on body composition altera=
tions during resistance training. Twenty-eight resistance-trained males b=
lindly supplemented their diets with maltodextrin (M), Gainers Fuel(R) 10=
00 (GF), or Phosphagain(TM) (P). No significant differences were observed=
in absolute or relative total body water among groups. Energy intake and=
body weight significantly increased in all groups combined throughout th=
e study with no group or interaction differences observed. Dual energy x-=
ray absorptiometry-determined body mass significantly increased in each g=
roup throughout the study with significantly greater gains observed in th=
e GF and P groups. Lean tissue mass (excluding bone) gain was significant=
ly greater in the P group, while fat mass and percent body fat were signi=
ficantly increased in the GF group. Results indicate that total body weig=
ht significantly increased in each group and that P supplementation resul=
ted in significantly greater gains in lean tissue mass during resistance =
training.
=0D
Authors OK Tsintzas, C Williams, L Boobis, P Greenhaff
Title Carbohydrate Ingestion and Single Muscle-Fiber Glycogen-Metabolism =
During Prolonged Running in Men
Full source Journal of Applied Physiology, 1996, Vol 81, Iss 2, pp 801-80=
9
Author keywords Glycogen Depletion; Fatigue
KeyWords Plus HUMAN SKELETAL-MUSCLE; EXERCISE; GLUCOSE; PERFORMANCE; PLAS=
MA; BLOOD; FRUCTOSE; REST
TGA/Book No. VD228
Discipline Sports Science & Medicine
Document type Article
Language English
Address Williams C, Loughborough Univ Technol, Dept Phys Educ Sports Sci =
& Recreat Management, Loughborough LE11 3TU, Leics, ENGLAND
ISBN/ISSN 8750-7587
Publisher Amer Physiological Soc, 9650 Rockville Pike, Bethesda, MD 20814=
Abstract The aim of this study was to examine the effect of carbohydrate =
(CHO-I ingestion on glycogen degradation in type I and type II muscle fib=
ers during prolonged running by using a quantitative biochemical method. =
To this end, eight male subjects ran at 70% maximal oxygen uptake to exha=
ustion on a motorized treadmill on two occasions, 1 wk apart. On each occ=
asion, the subjects ingested 8 ml/kg body wt of either placebo (Pi) or a =
5.5% CHO-electrolyte solution (CHO-E) immediately before the start of the=
run and 2 ml/kg body wt every 20 min thereafter. Needle biopsy samples w=
ere obtained from the vastus lateralis muscle before and after each trial=
and also at the time coinciding with Fl exhaustion in the CHO-E trial. R=
unning time to exhaustion was longer (P < 0.01) in the CHO-E trial compar=
ed with the P1 trial (132.4 +/- 12.3 and 104.3 +/- 8.6 min, respectively)=
=2E A 25% reduction in glycogen utilization in type I fibers only was obs=
erved in the CHO-E trial compared with the P1 trial (215.2 +/- 27.5 vs. 2=
85.4 +/- 30.1 mmol/kg dry wt; P < 0.01). Furthermore, in the CHO-E trial,=
in contrast to the Fl trial, both muscle ATP and phosphocreatine concent=
rations were well maintained throughout exercise. Therefore, because in b=
oth the P1 and CHO-E trials the type I fibers were glycogen depleted at t=
he point of exhaustion (31.6 +/- 10.3 and 28.1 +/- 7.1 mmol/kg dry wt, re=
spectively), it is proposed that CHO ingestion improved endurance capacit=
y by contributing to oxidative ATP production specifically in type I fibe=
rs and by doing so delayed the development of glycogen depletion in this =
fiber type.
=0D
Authors JO Holloszy, WM Kohrt
Title Regulation of Carbohydrate and Fat-Metabolism During and After Exer=
cise
Full source Annual Review of Nutrition, 1996, Vol 16, pp 121-138
Author keywords Glycogen; Glucose; Triglycerides; Free Fatty Acids; Maxim=
al Oxygen Uptake Capacity
KeyWords Plus MUSCLE RESPIRATORY CAPACITY; RAT SKELETAL-MUSCLES; GLUCOSE-=
TRANSPORT; ENDURANCE EXERCISE; GLYCOGEN UTILIZATION; PHOSPHORYLASE-ACTIVI=
TY; SUBMAXIMAL EXERCISE; LACTATE THRESHOLD; LIVER-GLYCOGEN; INSULIN
TGA/Book No. UZ316
Discipline Sports Science & Medicine
Document type Review
Language English
Address Holloszy JO, Washington Univ, Sch Med, Dept Internal Med, St Loui=
s,MO 63110 USA
ISBN/ISSN 0199-9885
Publisher Annual Reviews Inc, 4139 El Camino Way, PO Box 10139, Palo Alto=
, CA 94303-0139
Abstract During vigorous exercise, carbohydrate, in the form of muscle gl=
ycogen and blood glucose, is the primary energy source, whereas fatty aci=
ds play a secondary, carbohydrate-sparing role. In the postabsorptive sta=
te, nearly all of the carbohydrate used during exercise comes from muscle=
and liver glycogen. The size of these glycogen stores plays a major role=
in determining how long vigorous endurance exercise can be performed if =
other causes of fatigue, such as dehydration or heat exhaustion, are avoi=
ded. In a ''fight or flight'' situation, individuals whose muscles are gl=
ycogen depleted are helpless, as they are unable to either run or fight. =
The same is true of someone who has become markedly hypoglycemic as a res=
ult of liver glycogen depletion.
=0D
Authors BH Goodpaster, DL Costill, WJ Fink, TA Trappe, AC Jozsi, RD Starl=
ing, SW Trappe
Title The Effects of Preexercise Starch Ingestion on Endurance Performanc=
e
Full source International Journal of Sports Medicine, 1996, Vol 17, Iss 5=
, pp 366-372
Author keywords Starch; Blood Glucose; Cycling Performance
KeyWords Plus PROLONGED STRENUOUS EXERCISE; CARBOHYDRATE FEEDINGS; CYCLIN=
G PERFORMANCE; INSULIN RESPONSES; GLUCOSE; OXIDATION; FRUCTOSE; FATIGUE; =
CORN; FOOD
TGA/Book No. UZ455
Discipline Sports Science & Medicine
Document type Article
Language English
Address Costill DL, Ball State Univ, Human Performance Lab, Muncie,IN 473=
06 USA
ISBN/ISSN 0172-4622
Publisher Georg Thieme Verlag, P O Box 30 11 20, D-70451 Stuttgart, Germa=
ny
Abstract This study compared the physiological responses and performance =
following the ingestion of a waxy starch (WS), resistant starch (RS), glu=
cose (GL) and an artifiially-sweetened placebo (Pi.) ingesed prior to exe=
rcise. Ten college-age, male competitive cyclists completed four experime=
ntal protocols consisting of a 30 min isokinetic, self-paced performance =
ride preceded by 90 min of constant load cycling at 66 % VO(2)max. Thirty=
min prior to exercise, they ingested 1 g . Kg(-1) body weight of GL, WS,=
RS, or PL. At rest, GL elicited greater (p<0.05) serum glucose and insul=
in responses than all other trials. During exercise, however, serum gluco=
se, insulin, blood C-peptide and glucagon responses were similar among tr=
ials. The mean total carbohydrate oxidation rates (CHOox) were higher (p<=
0.05) during the GL, WS, and RS trials (2.59+/-0.13, 2.49+/-0.10, and 2.7=
1+/-0.15 g min(-1), respectively) compared to PL (2.35+/-0.12 g min(-1)).=
Subjects were able to complete more work (p<0.05) during the performance=
ride when they ingested GL (434+/-25.2 kJ) or WS (428+/-22.5 kJ) compare=
d to PL (403+/-35.1 kJ). They also tended to produce more work with RS in=
gestion (418+/-31.4 kJ), although this did not reach statistical signific=
ance (p<0.09). These results indicate that preexercise-CHO ingestion in t=
he form of starch or glucose maintained higher rates of total carbohydrat=
e oxidation during exercise and provided an ergogenic benefit during self=
-paced cycling.
=0D
=0D
Authors RAB Lapachet, WC Miller, DA Arnall
Title Body-Fat and Exercise Endurance in Trained Rats Adapted to a High-F=
at and/or High-Carbohydrate Diet
Full source Journal of Applied Physiology, 1996, Vol 80, Iss 4, pp 1173-1=
179
Author keywords Diet Composition; Dietary Fat; Dietary Carbohydrate; Body=
Composition; Endurance Exercise; Carbohydrate Loading
KeyWords Plus GLYCOGEN DEPLETION PATTERNS; LIPOPROTEIN-LIPASE ACTIVITY; S=
KELETAL-MUSCLE FIBERS; TRIGLYCERIDE UTILIZATION; HIGH-PROTEIN; ENERGY; ME=
TABOLISM; INTENSITY; OXIDATION; RECOVERY
TGA/Book No. UF112
Discipline Sports Science & Medicine
Document type Article
Language English
Address Miller WC, George Washington Univ, Sch Med, Exercise Sci Programs=
, 817 23RD St NW, Washington,DC 20052 USA
ISBN/ISSN 8750-7587
Publisher Amer Physiological Soc, 9650 Rockville Pike, Bethesda, MD 20814=
Abstract To study how diet composition affects exercise endurance and bod=
y composition, 48 male Sprague-Dawley rats were treadmill trained for 8 w=
k while consuming either a high-fat (F) diet or high-carbohydrate (C) die=
t. The diets were switched for one-half the number of rats in each group =
3 days before the animals were killed, during which feeding time the rats=
did not exercise. One-half of rats receiving each of the four diet combi=
nations were taken at rest (R) or exhaustion (E), resulting in eight grou=
ps: CCR, CFR, FFR, FCR, CCE, CFE, FFE, and FCE. An analysis of variance r=
evealed that resting glycogen in the FCR group was enhanced in muscle (19=
-33%) and liver (23%) compared with controls. Each F group's exercise tim=
e to exhaustion [CFE, 322.9 +/- 25.0; FFE, 356.8 +/- 37.8; FCE, 467.0 +/-=
32.6 (SE) mini was different (P < 0.05) from control (CCE, 257.5 +/- 29.=
2 min). Postexercise glycogen was equivalent among all dietary groups, as=
were muscle triglycerides. The FF and FC groups had higher 3-hydroxyacyl=
-CoA dehydrogenase activity in soleus muscle than either CC or CF animals=
=2E After training, body weights were similar between the two dietary gro=
ups; however, percent body fat was 17% greater after the F diet, even tho=
ugh F diet animals voluntarily consumed 12% less energy than did C diet a=
nimals. These data suggest that exercise endurance time is optimized in t=
rained rats that receive a carbohydrate load after adaptation to a F diet=
=2E However, despite intense exercise training, the F diet promotes body =
fat deposition, and the health consequences of following such a regimen a=
re still unknown.
=0D
Authors JL Fallowfield, C Williams, R Singh
Title The Influence of Ingesting a Carbohydrate-Electrolyte Beverage Duri=
ng 4 Hours of Recovery on Subsequent Endurance Capacity
Full source International Journal of Sport Nutrition, 1995, Vol 5, Iss 4,=
pp 285-299
Author keywords Carbohydrate Metabolism; Rehydration; Running
TGA/Book No. TG994
Discipline Sports Science & Medicine
Document type Article
Language English
Address Williams C, Loughborough Univ Technol, Dept Phys Educ Sports Sci =
& Recreat Management, Loughborough LE11 3TU, Leics, ENGLAND
ISBN/ISSN 1050-1606
Publisher Human Kinetics Publ Inc, 1607 N Market St, Box 5076, Champaign,=
IL 61820-5076
Abstract Recovery from prolonged exercise involves both rehydration and r=
eplenishment of endogenous carbohydrate stores. The present study examine=
d the influence of ingesting a carbohydrate-electrolyte (CE) solution fol=
lowing prolonged running, on exercise capacity 4 hr later. Twelve men and=
4 women were divided into two matched groups, which were randomly assign=
ed to either a control (P) or a carbohydrate (CHO) condition. Both groups=
ran at 70% of maximal oxygen uptake (VO(2)max) on a level treadmill for =
90 min or until volitional fatigue (R(1)), and they ran at the same %VO(2=
)max to exhaustion 4 hr later to assess endurance capacity (R(2)) The CHO=
group ingested a 6.9% CE solution providing 1.0 g CHO . Kg body weight(-=
1) immediately post-R(1) and again 2 hr later. The P group ingested equal=
volumes of a placebo solution. Run times (mean +/- SEM) for R(1) did not=
differ between the groups (P 86.3 +/- 3.8 min; CHO 87.5 +/- 2.5 min). Th=
e CHO group ran 22.2 (+/-3.5) min longer than the P group during R(2) (P =
39.8 +/- 6.1 min; CHO 62.0 +/- 6.2 min) (p < .05). Thus, ingesting a 6.9%=
carbohydrate-electrolyte beverage following prolonged, constant-pace run=
ning improves endurance capacity 4 hr later.
=0D
Authors J Kang, RJ Robertson, BG Denys, SG Dasilva, P Visich, RR Suminski=
, AC Utter, FL Goss, KF Metz
Title Effect of Carbohydrate Ingestion Subsequent to Carbohydrate Superco=
mpensation on Endurance Performance
Full source International Journal of Sport Nutrition, 1995, Vol 5, Iss 4,=
pp 329-343
Author keywords Carbohydrate Supplementation; Blood Glucose; Carbohydrate=
Oxidation; Ergogenic Acid
TGA/Book No. TG994
Discipline Sports Science & Medicine
Document type Article
Language English
Address Kang J, Rowan Coll, Dept Hlth & Exercise Sci, 201 Mullica Hill Rd=
, Glassboro,NJ 08028 USA
ISBN/ISSN 1050-1606
Publisher Human Kinetics Publ Inc, 1607 N Market St, Box 5076, Champaign,=
IL 61820-5076
Abstract This investigation determined whether carbohydrate ingestion dur=
ing prolonged moderate-intensity exercise enhanced endurance performance =
when the exercise was preceded by carbohydrate supercompensation. Seven m=
ale trained cyclists performed two trials at an initial power output corr=
esponding to 71 +/- 1% of their peak oxygen consumption. During the trial=
s, subjects ingested either a 6% glucose/sucrose (C) solution or an equal=
volume of artificially flavored and sweetened placebo (P) every 20 min t=
hroughout exercise. Both C and P were preceded by a 6-day carbohydrate su=
percompensation procedure in which subjects undertook a depletion-taper e=
xercise sequence in conjunction with a moderate- and high-carbohydrate di=
et regimen. Statistical analysis of time to exhaustion, plasma glucose co=
ncentration, carbohydrate oxidation rate, fat oxidation rate, and plasma =
glycerol concentration indicated that in spite of a carbohydrate supercom=
pensation procedure administered prior to exercise, carbohydrate ingestio=
n during exercise can exert an additional ergogenic effect by preventing =
a decline in blood glucose levels and maintaining carbohydrate oxidation =
during the later stages of moderate-intensity exercise.
=0D
Authors OK Tsintzas, C Williams, L Boobis, P Greenhaff
Title Carbohydrate Ingestion and Glycogen Utilization in Different Muscle=
-Fiber Types in Man
Full source Journal of Physiology - London, 1995, Vol 489, Iss 1, pp 243-=
250
KeyWords Plus HUMAN SKELETAL-MUSCLE; EXERCISE PERFORMANCE; FIBER TYPES; G=
LUCOSE; METABOLISM; FRUCTOSE; PLASMA; BLOOD; CONTRACTION; DEPLETION
TGA/Book No. TH853
Discipline Sports Science & Medicine
Document type Article
Language English
Address Williams C, Loughborough Univ Technol, Dept Phys Educ Sports Sci =
& Recreat Management, Loughborough LE11 3TU, Leics, ENGLAND
ISBN/ISSN 0022-3751
Publisher Cambridge Univ Press, 40 West 20TH Street, New York, NY 10011-4=
211
Abstract 1. The effect of carbohydrate (CHO) ingestion on muscle glycogen=
utilization during exercise was examined on seven male subjects completi=
ng two 60 min treadmill runs at 70% maximum oxygen uptake (V-O2,V-max), 1=
week apart. On each occasion the subjects consumed either water or a 5.5=
% CHO-electrolyte solution immediately before and during exercise. Muscle=
samples were obtained from the vastus lateralis by needle biopsy before =
and immediately after exercise. Venous blood samples were also collected =
from an ante-cubital vein at rest and at 10, 20, 40 and 60 min into the r=
un. 2. Higher blood glucose concentrations (P<0.01) were observed through=
out the run during the CHO trial compared with the water trial. Serum ins=
ulin concentration was only higher after 20 min of exercise (P<0.01). 3. =
A 28% reduction in mixed glycogen utilization was observed as a result of=
CHO ingestion when compared with water ingestion (108.7 +/- 16.3 vs. 150=
=2E9 +/- 19.9 mmol (kg dry matter)(-1), respectively; P<0.01). 4. The ing=
estion of the CHO solution resulted in sparing of glycogen in type I (slo=
w twitch)) fibres only (38 +/- 7% degradation of glycogen as opposed to 6=
6 +/- 3% during the water trial; P=3D0.01).
=0D
Authors LHG Rauch, AN Bosch, TD Noakes, SC Dennis, JA Hawley
Title Fuel Utilization During Prolonged Low-to-Moderate Intensity Exercis=
e When Ingesting Water or Carbohydrate
Full source Pflugers Archiv - European Journal of Physiology, 1995, Vol 4=
30, Iss 6, pp 971-977
Author keywords Glucose Turnover and Oxidation; Fat Oxidation
KeyWords Plus STRENUOUS EXERCISE; MUSCLE GLYCOGEN; TURNOVER; PERFORMANCE;=
METABOLISM; OXIDATION
TGA/Book No. TE429
Discipline Sports Science & Medicine
Document type Article
Language English
Address Hawley JA, Univ Cape Town, Sch Med, Dept Physiol, MRC, Bioenerget=
Exercise Res Unit, Cape Town 7925, SOUTH AFRICA
ISBN/ISSN 0031-6768
Publisher Springer Verlag, 175 Fifth Ave, New York, NY 10010
Abstract Previously, we examined the effects of carbohydrate (CHO) ingest=
ion on glucose kinetics during exercise at 70% of maximum O-2 uptake (VO2=
max). Here we repeat those studies in heavier cyclists (n =3D 6 per group=
) cycling for 3 h at a similar absolute O-2 uptake but at a lower (55% of=
VO2max) relative exercise intensity. During exercise, the cyclists were =
infused with a 2-H-3-glucose tracer and ingested U-C-14 glucose-labelled =
solutions of either flavoured water (H2O) or 10 g/100 ml glucose polymer,=
at a rate of 600 ml/h. Two subjects in the H2O trial fatigued after 2.5 =
h of exercise. Their rates of glucose appearance (R(a)) declined from 2.9=
+/-0.6 to 2.0+/-0.1 mmol/min (mean+/-SEM) and, as their plasma glucose co=
ncentration [Glu] declined from 4.7+/-0.2 to below 3.5+/-0.2 mM, their ra=
tes of glucose oxidation (R(ox)) and fat oxidation plateaued at 2.7+/- 0.=
4 and 1.7+/-0.1 mmol/min respectively. In contrast, all subjects complete=
d the CHO trial. Although CHO ingestion during exercise reduced the final=
endogenous R(a) from 3.4+/-0.6 to 0.9+/-0.3 mmol/min at the end of exerc=
ise, it increased total R(a) to 5.5+/-0.5 mmol/min (P < 0.05). A higher t=
otal R(a) with CHO ingestion raised [Glu] from 4.3+/-0.3 to 5.3+/-0.1 mM =
and accelerated R(ox) from 3.5+/-0.2 to 5.9+/-0.2 mmol/min after 180 min =
of exercise (P < 0.05). The increased contribution to total energy produc=
tion from glucose oxidation (34+/-1 vs. 20+/-1%) decreased energy product=
ion from fat oxidation from 51+/-2 to 40+/-5% (P =3D 0.08) and produced p=
atterns of glucose, muscle glycogen (plus lactate) and fat utilisation si=
milar to those during exercise at 70% of (VO2max). Thus, CHO ingestion is=
necessary to sustain even prolonged, low to moderate intensity exercise =
and when ingested, it suppresses the higher relative rates of fat oxidati=
on usually observed at exercise intensities less than 60% of VO2max.
=0D
Authors R Anantaraman, AA Carmines, GA Gaesser, A Weltman
Title Effects of Carbohydrate Supplementation on Performance During 1 Hou=
r of High-Intensity Exercise
Full source International Journal of Sports Medicine, 1995, Vol 16, Iss 7=
, pp 461-465
Author keywords Exercise; Glucose Polymer; Ergogenic Acids
KeyWords Plus PROLONGED STRENUOUS EXERCISE; ENDURANCE PERFORMANCE; GLUCOS=
E-INGESTION; GLYCOGEN USE; FEEDINGS; CAFFEINE; FATIGUE; FLUID; DIET
TGA/Book No. RZ855
Discipline Sports Science & Medicine
Document type Article
Language English
Address Weltman A, Univ Virginia, Curry Sch Educ, Dept Human Serv, Mem Gy=
mnasium, Exercise Physiol Lab, Charlottesville,VA 22903 USA
ISBN/ISSN 0172-4622
Publisher Georg Thieme Verlag, P O Box 30 11 20, D-70451 Stuttgart, Germa=
ny
Abstract The effects of carbohydrate supplementation on high-intensity ex=
ercise performance were examined in 5 moderately-trained subjects (age =3D=
28.4 +/- 1.5 yr; ht =3D 171.0 +/- 4.3 cm; wt =3D 66.25 +/- 6.32 kg). Hig=
h-intensity exercise tests (initiated at the power output (PO) associated=
with 90 % VO2 peak [mean =3D 201 +/- 21 watts] x 60 min, with drop-off i=
n PO allowed overtime) were completed under the following randomized doub=
le blind conditions: 1) pre-exercise glucose polymer (G)/placebo during e=
xercise (G/P), 2) G pre-exercise and during exercise (G/G), and 3) placeb=
o pre-exercise and during exercise (P/P). Subjects ingested 300 ml of a s=
weetened placebo or a similarly flavored 10 % G solution, immediately pri=
or to and every 15 min during exercise. No differences were observed in P=
O among the 3 treatments until min 40-60 where PO was greater with C. Thi=
s resulted in significantly greater total work (and less drop-off in PO) =
with G (G/P =3D 619 +/- 234 kJ [14.5 % lower than the value associated wi=
th 201 watts maintained for 60 min {724 kJ}], G/G =3D 599 +/- 235 kJ [17.=
3 % lower than the value associated with 201 watts maintained for 60 min]=
) compared with placebo (P/P =3D 560 +/- 198 kJ [22.7% drop-off in averag=
e PO]) (p < 0.05). VO2 followed a similar pattern with no differences in =
VO2 over min 0 - 40 and significantly higher VO2 in G/P and a trend for h=
igher VO2 in G/G during min 40-60 compared to placebo. Results of the pre=
sent study indicate that, compared to placebo, pre-exercise ingestion of =
G (30 g in 10 % solution) results in less drop-off in PO during 1 hour of=
high-intensity exercise performance, and that no further benefit is obse=
rved when the same amount of G is also ingested every 15 min during exerc=
ise.
=0D
Authors MS Elsayed, AJM Rattu, I Roberts
Title Effects of Carbohydrate Feeding Before and During Prolonged Exercis=
e on Subsequent Maximal Exercise Performance Capacity
Full source International Journal of Sport Nutrition, 1995, Vol 5, Iss 3,=
pp 215-224
Author keywords Glucose Feeding; Metabolic Substrates; Exhaustive Physica=
l Exertion
TGA/Book No. RR161
Discipline Sports Science & Medicine
Document type Article
Language English
Address Elsayed MS, Manchester Metropolitan Univ, Crewe & Alsager Fac, Di=
v Sports Sci, Hassall Rd, Stoke on Trent ST7 2HL, Staffs, ENGLAND
ISBN/ISSN 1050-1606
Publisher Human Kinetics Publ Inc, 1607 N Market St, Box 5076, Champaign,=
IL 61820-5076
Abstract The study examined the effect of carbohydrate ingestion on exerc=
ise performance capacity. Nine male cyclists performed two separate trial=
s at 70% VO(2)max for 60 min followed by a maximal ride for 10 min. Durin=
g trials subjects were fed either an 8% glucose solution (CHO) or a place=
bo solution (PL), which were administered at rest and during and immediat=
ely after submaximal exercise. Statistical analyses indicated that glucos=
e levels at rest increased significantly 15 min after the ingestion of CH=
O compared to FL. At 30 and 60 min during submaximal exercise, plasma glu=
cose levels decreased significantly in the CHO but nor in the PL trial. F=
ollowing the performance ride, glucose levels increased significantly onl=
y during the CHO test trial. Free fatty acids did not change significantl=
y during testing trials. The maximal performance ride results showed that=
in the CHO trial, a significantly greater external work load was accompl=
ished compared to the PL trial. It is concluded that CHO ingestion improv=
es maximal exercise performance after prolonged exercise.
=0D
Authors DPC Leijssen, WHM Saris, AE Jeukendrup, AJM Wagenmakers
Title Oxidation of Exogenous <C-13>Galactose and <C-13>Glucose During Exe=
rcise
Full source Journal of Applied Physiology, 1995, Vol 79, Iss 3, pp 720-72=
5
Author keywords Galactose; Glucose; C-13 Labeling; Carbohydrate Oxidation=
; Blood Metabolites
KeyWords Plus PROLONGED EXERCISE; GLUCOSE-OXIDATION; METABOLIC RESPONSE; =
CARBOHYDRATE; INGESTION; GALACTOSE; FRUCTOSE
TGA/Book No. RV192
Discipline Sports Science & Medicine
Document type Article
Language English
Address Leijssen DPC, Univ Limburg, Dept Human Biol, Nutr Res Ctr, POB 61=
6, 6200 MD Maastricht, NETHERLANDS
ISBN/ISSN 8750-7587
Publisher Amer Physiological Soc, 9650 Rockville Pike, Bethesda, MD 20814=
Abstract The present study examined the oxidation of exogenous galactose =
or glucose during prolonged submaximal cycling exercise. Eight highly tra=
ined volunteers exercised on two occasions on a cycle ergometer at 65% of=
maximal workload for 120 min, followed by a 60-min rest period and a sec=
ond exercise bout of 30 min at 60% maximal workload. At random, subjects =
ingested a 8% galactose solution to which an [1-13C]galactose tracer was =
added or a 8% glucose solution to which an [U-C-13]glucose tracer was add=
ed. Drinks were provided at the end of the warm-up period (8 ml/kg) and e=
very 15 min (2 ml/kg) during the first 120 min of the test. Blood and bre=
ath samples were collected every 30 and 15 min, respectively, during the =
test. The exogenous carbohydrate (CHO) oxidation was calculated from the =
(CO2)-C-13/(CO2)-C-12 ratio and CO2 production of the expired air. Peak e=
xogenous CHO oxidation during exercise for galactose and glucose was 0.41=
+/- 0.03 and 0.85 +/- 0.04 g/min, respectively. Total CHO and fat oxidat=
ion were not significantly different between the treatments. Forty-six pe=
rcent of the ingested glucose was oxidized, whereas only 21% of the inges=
ted galactose was oxidized. As a consequence, more endogenous CHO was uti=
lized with galactose than with glucose (124.4 +/- 6.7 and 100.1 +/- 3.6 g=
, respectively). These results indicate that the oxidation rate of orally=
ingested galactose is maximally similar to 50% of the oxidation rate of =
a comparable amount of orally ingested glucose during 120 min of exercise=
=2E
=0D
Authors CW Nicholas, C Williams, HKA Lakomy, G Phillips, A Nowitz
Title Influence of Ingesting a Carbohydrate-Electrolyte Solution on Endur=
ance Capacity During Intermittent, High-Intensity Shuttle Running
Full source Journal of Sports Sciences, 1995, Vol 13, Iss 4, pp 283-290
Author keywords Carbohydrate-Electrolyte Solutions; Endurance; Fatigue; F=
luid Intake; Sprinting
TGA/Book No. RP580
Discipline Sports Science & Medicine
Document type Article
Language English
Address Williams C, Loughborough Univ Technol, Dept Phys Educ Sports Sci =
& Recreat Management, Loughborough LE11 3TU, Leics, ENGLAND
ISBN/ISSN 0264-0414
Publisher E & Fn Spon, 2-6 Boundary Row, London, England SE1 8HN
Abstract The aim of this study was to examine the effects of ingesting a =
carbohydrate-electrolyte solution on endurance capacity during a prolonge=
d intermittent, high-intensity shuttle running test (PIHSRT). Nine traine=
d male games players performed two exercise trials, 7 days apart. On each=
occasion, they completed 75 min exercise, comprising of five 15-min peri=
ods of intermittent running, consisting of sprinting, interspersed with p=
eriods of jogging and walking (Part A), followed by intermittent running =
to fatigue (Part B). The subjects were randomly allocated either a 6.9% c=
arbohydrate-electrolyte solution (CHO) or a non-carbohydrate placebo (CON=
) immediately prior to exercise (5 ml kg(-1) body mass) and every 15 min =
thereafter (2 ml kg(-1) body mass). Venous blood samples were obtained at=
rest, during and after each PIHSRT for the determination of glucose, lac=
tate, plasma free fatty acid, glycerol, ammonia, and serum insulin and el=
ectrolyte concentrations. During Part B, the subjects were able to contin=
ue running longer when fed CHO (CHO =3D 8.9 +/- 1.5 min vs CON =3D 6.7 +/=
- 1.0 min; P < 0.05) (mean +/- S.E.M.). These results show that drinking =
a carbohydrate-electrolyte solution improves endurance running capacity d=
uring prolonged intermittent exercise.
=0D
Authors WM Sherman
Title Metabolism of Sugars and Physical Performance
Full source American Journal of Clinical Nutrition, 1995, Vol 62, Iss 1, =
Suppl., pp S228-S241
Author keywords Carbohydrate; Exertion; Physical Activity; Fat
KeyWords Plus MUSCLE GLYCOGEN-STORAGE; EXOGENOUS CARBOHYDRATE OXIDATION; =
PROLONGED STRENUOUS EXERCISE; ENDURANCE PERFORMANCE; DIETARY CARBOHYDRATE=
; GLYCEMIC-INDEX; INTERMITTENT EXERCISE; SUBMAXIMAL EXERCISE; CYCLING PER=
FORMANCE; INGESTION
TGA/Book No. RK076
Discipline Sports Science & Medicine
Document type Article
Language English
Address Sherman WM, Ohio State Univ, Hper Dept, 129 Larkins Hall, 337 W 1=
7TH Ave, Columbus,OH 43210 USA
ISBN/ISSN 0002-9165
Publisher Amer Soc Clin Nutrition Inc, 9650 Rockville Pike, Subscriptions=
, RM L-2310, Bethesda, MD 20814-3998
Abstract Physical activity in the form of exercise requires the metabolis=
m of bodily fuel reserves to provide energy for muscle contraction. Under=
normal circumstances, very little protein is metabolized to provide the =
energy for muscle contraction. At rest and at low exercise intensities, t=
he metabolism of fat provides a considerable proportion of the energy for=
resting metabolic processes and muscle contraction. However, at exercise=
intensities at which athletes train and compete, the metabolism of bodil=
y carbohydrate reserves (eg, blood glucose and liver and muscle glycogen)=
provides the predominant: fuel for muscle contraction. Furthermore, when=
these substrates reach critically low amounts or are decreased by some a=
mount, fatigue occurs. There is a significant body of literature examinin=
g the effects of ingestion of various types of sugars at various times du=
ring exercise and during recovery from exercise on carbohydrate fuel rese=
rves and on physical performance.
=0D
Authors C Williams
Title Macronutrients and Performance
Full source Journal of Sports Sciences, 1995, Vol 13, Sp. Iss., pp S1-S10=
Author keywords Athletes; Carbohydrate; Exercise; Fat; Fatigue; Performan=
ce; Protein
TGA/Book No. RK855
Discipline Sports Science & Medicine
Document type Article
Language English
Address Williams C, Loughborough Univ Technol, Dept Phys Educ Sports Sci =
& Recreat Management, Loughborough LE11 3TU, Leics, ENGLAND
ISBN/ISSN 0264-0414
Publisher E & Fn Spon, 2-6 Boundary Row, London, England SE1 8HN
Abstract Athletes should eat a well-balanced diet made up of a wide varie=
ty of foods in sufficient quantity to cover their daily energy expenditur=
es. Carbohydrate-containing foods should provide similar to 60-70% of the=
ir daily energy intake, protein similar to 12-15%, with the remainder bei=
ng provided by fat. The higher carbohydrate intakes, however, are only re=
commended during preparation for, and immediate recovery from, heavy trai=
ning and competition. Adopting nutritional strategies to increase muscle =
and liver glycogen stores before, during and after exercise can improve p=
erformance. The protein requirements of most athletes are fulfilled when =
their daily intake is between 1.2 and 1.7 g per kg body mass. This amount=
of protein is provided by a diet which covers the athlete's daily energy=
expenditure. Although fat metabolism contributes to energy production du=
ring exercise, and the amount increases with endurance training, there is=
no evidence to suggest that athletes should increase their fat intake as=
a means of improving their performance.
=0D
Authors FX Pizza, MG Flynn, BD Duscha, J Holden, ER Kubitz
Title A Carbohydrate Loading Regimen Improves High-Intensity, Short-Durat=
ion Exercise Performance
Full source International Journal of Sport Nutrition, 1995, Vol 5, Iss 2,=
pp 110-116
Author keywords Lactate; Diet; Athletes; Dietary Carbohydrate; Fatigue
TGA/Book No. RC433
Discipline Sports Science & Medicine
Document type Article
Language English
Address Pizza FX, Texas Christian Univ, Dept Educ Phys, FT Worth,TX 76129=
USA
ISBN/ISSN 1050-1606
Publisher Human Kinetics Publ Inc, 1607 N Market St, Box 5076, Champaign,=
IL 61820-5076
Abstract This investigation examined the effect of a carbohydrate loading=
regimen on high intensity, short duration run performance. Using a rando=
m crossover design, 8 trained runners completed a 15-min submaximal run a=
nd a performance run to exhaustion after two dietary treatments. The mixe=
d diet (MD) contained 4.0 +/- 0.5 g . Kg(-1) . D(-1) of carbohydrate (CHO=
) for 6 days. The experimental diet (HCD) contained 4.5 +/- 0.5 g CHO . K=
g(-1) . D(-1) for 3 days followed by 8.2 +/- 0.4 g CHO . Kg(-1) . D(-1) f=
or 3 days. Training consisted of daily runs of 90, 40, 40, 20, and 20 min=
at approximately 75% of VO(2)max. Day 6 was a rest day, and testing was =
completed on Day 7. Preexercise lactate, body weight, submaximal VO2, and=
heart rate did not differ significantly between treatments. Carbohydrate=
oxidation during submaximal running was higher (p < 0.05) after HCD than=
after MD. Time to exhaustion in the performance run was longer after HCD=
compared to MD. Results indicate that a carbohydrate loading regimen inc=
reases CHO oxidation during submaximal exercise and improves high intensi=
ty, short duration run performance.
=0D
Authors TC Ball, SA Headley, PM Vanderburgh, JC Smith
Title Periodic Carbohydrate Replacement During 50 Min of High-Intensity C=
ycling Improves Subsequent Sprint Performance
Full source International Journal of Sport Nutrition, 1995, Vol 5, Iss 2,=
pp 151-158
Author keywords Wingate Anaerobic Test; Glycogen; Ergogenic AIDS
TGA/Book No. RC433
Discipline Sports Science & Medicine
Document type Article
Language English
Address Headley SA, Springfield Coll, Dept Educ Phys, Springfield,MA 0110=
9 USA
ISBN/ISSN 1050-1606
Publisher Human Kinetics Publ Inc, 1607 N Market St, Box 5076, Champaign,=
IL 61820-5076
Abstract The purpose of this study was to investigate the effect of 7% ca=
rbohydrate electrolyte (CE) drink on sprint capacity immediately followin=
g 50 min of high intensity cycling. After an overnight 12-hr fast, 8 trai=
ned male cyclists performed two 50-min simulated time trials on a Monark =
stationary cycle ergometer. Subjects consumed either the CE or a flavored=
water placebo (PL) at 10, 20, 30, and 40 min during the time trial. At t=
he conclusion of each 50-min time trial, subjects immediately performed a=
Wingate Anaerobic Power Test. Peak power, mean power, and minimum power =
were significantly higher for the CE trials, whereas mean RPE was signifi=
cantly lower. Mean heart rate and fatigue index were not different betwee=
n trials. These results suggest that sprint performance following a high =
intensity simulated time trial of only 50 min can be improved with period=
ic consumption of CE during the ride, particularly following an overnight=
fast, when liver glycogen is likely to be low. These findings have impli=
cations for competitive cycling, where sprint capacity at the conclusion =
of a race is an important determinant of success.
=0D
Authors J Walbergrankin
Title Dietary Carbohydrate as an Ergogenic Aid for Prolonged and Brief Co=
mpetitions in Sport
Full source International Journal of Sport Nutrition, 1995, Vol 5, Suppl.=
, pp S13-S28
TGA/Book No. RC689
Discipline Sports Science & Medicine
Document type Article
Language English
Address Walbergrankin J, Virginia Tech, Dept Human Nutr & Foods, Hlth & E=
xercise Sci Lab, Blacksburg,VA 24061 USA
ISBN/ISSN 1050-1606
Publisher Human Kinetics Publ Inc, 1607 N Market St, Box 5076, Champaign,=
IL 61820-5076
Abstract Reduction of body stores of carbohydrate and blood glucose is re=
lated to the perception of fatigue and the inability to maintain high-qua=
lity performance. This has been clearly shown with aerobic, endurance eve=
nts of moderate intensity of over 90 min duration. Carbohydrate intake ma=
y also have relevance for athletes involved in short, high-intensity even=
ts, especially if body weight control is an issue. Prevention of carbohyd=
rate depletion begins with a high-carbohydrate training diet of about 60-=
70% carbohydrate, If possible, carbohydrate beverages should be consumed =
during the event at the rate of 30-70 g/hr to reduce the chance of body c=
arbohydrate depletion. Finally, replacement of body carbohydrate stores c=
an be achieved most rapidly if 40-60 g of carbohydrate is consumed as soo=
n as possible after the exercise and at repeating 1-hr intervals for at l=
east 5 hr after the event.
=0D
Authors G Schlabach
Title Carbohydrate Strategies for Injury Prevention
Full source Journal of Athletic Training, 1994, Vol 29, Iss 3, pp 244
TGA/Book No. QV012
Discipline Sports Science & Medicine
Document type Article
Language English
Address Schlabach G, No Illinois Univ, de Kalb,IL 60115 USA
ISBN/ISSN 1062-6050
Publisher Natl Athletic Trainers Assoc Inc, 2952 Stemmons Freeway, Dallas=
, TX 75247
Abstract Prevention of injury involves identifying risk factors that woul=
d predispose one to injury and developing strategies to attenuate or elim=
inate their presence. Because muscle glycogen depletion is associated wit=
h fatigue and injury, it should be treated as a possible risk factor. Mus=
cle glycogen stores are derived almost entirely from carbohydrate intake.=
Because there is a limited capacity to store muscle glycogen, and becaus=
e muscle glycogen is the predominant fuel in exercise of moderate to seve=
re intensity, the nutritional focus should be on carbohydrate consumption=
=2E Easy-to-follow nutritional strategies should be employed that will ma=
ximize muscle glycogen stores and delay the onset of fatigue. Individuals=
involved in activities lasting less than 60 minutes need to consume an a=
dequate amount of carbohydrate daily and a pre-event meal before the star=
t of the activity. However, individuals participating in activities longe=
r than 60 minutes or participating in activities requiring repeated bouts=
of high intensity exercise need to: 1) consume an adequate amount of car=
bohydrate daily, 2) practice carbohydrate loading, 3) consume the pre-eve=
nt meal, and 4) ingest carbohydrates immediately before, during and after=
the activity.
=0D
Authors LHG Rauch, I Rodger, GR Wilson, JD Belonje, SC Dennis, TD Noakes,=
JA Hawley
Title The Effects of Carbohydrate Loading on Muscle Glycogen-Content and =
Cycling Performance
Full source International Journal of Sport Nutrition, 1995, Vol 5, Iss 1,=
pp 25-36
Author keywords Diet; Potato Starch
TGA/Book No. QH532
Discipline Sports Science & Medicine
Document type Article
Language English
Address Rauch LHG, Univ Cape Town, Sch Med, Dept Physiol, MRC, Bioenerget=
Exercise Res Unit, Cape Town 7925, SOUTH AFRICA
ISBN/ISSN 1050-1606
Publisher Human Kinetics Publ Inc, 1607 N Market St, Box 5076, Champaign,=
IL 61820-5076
Abstract This study compared the effects of supplementing the normal diet=
s of 8 endurance-trained cyclists with additional carbohydrate (CHO), in =
the form of potato starch, for 3 days on muscle glycogen utilization and =
performance during a 3-hr cycle ride. On two occasions prior to the tria=
l, the subjects ingested in random order either their normal CHO intake o=
f 6.15 +/- 0.23 g/kg body mass/day or a high-CHO diet of 10.52 +/- 0.57 g=
/kg body mass/day. The trial consisted of 2 hr of cycling at approximate=
ly 75% of VO2peak with five 60-s sprints at 100% VO2peak at 20-min interv=
als, followed by a 60-min performance ride. Increasing CHO intake by 72 =
+/- 9% for 3 days prior to the trial elevated preexercise muscle glycogen=
contents, improved power output, and extended the distance covered in 1 =
hr. Muscle glycogen contents were similar at the end of the 3-hr trial, =
indicating a greater utilization of glycogen when subjects were CHO loade=
d, which may have been responsible for their improved cycling performance=
=2E
=0D
Authors OK Tsintzas, C Williams, R Singh, W Wilson, J Burrin
Title Influence of Carbohydrate Electrolyte Drinks on Marathon Running Pe=
rformance
Full source European Journal of Applied Physiology and Occupational Physi=
ology, 1995, Vol 70, Iss 2, pp 154-160
Author keywords Carbohydrate Feeding; Marathon Running; Glucose Metabolis=
m; Hormonal Responses
KeyWords Plus MUSCLE GLYCOGEN UTILIZATION; PROLONGED EXERCISE; FLUID REPL=
ACEMENT; INGESTION; GLUCOSE; CAPACITY; RUNNERS; WATER; DIET; RACE
TGA/Book No. QG217
Discipline Sports Science & Medicine
Document type Article
Language English
Address Williams C, Loughborough Univ Technol, Dept Phys Educ Sports Sci =
& Recreat Management, Loughborough LE11 3TU, Leics, ENGLAND
ISBN/ISSN 0301-5548
Publisher Springer Verlag, 175 Fifth Ave, New York, NY 10010
Abstract The aim of this study was to compare the effects of drinking two=
carbohydrate (CHO) electrolyte solutions and water on marathon running p=
erformance. Seven endurance-trained runners completed three 42.2-km tread=
mill time-trials which were randomly assigned and 4 weeks apart. On each =
occasion the subjects ingested 3 ml.Kg(-1) body weight of either water (W=
), a 6.9% CHO solution (O) or a 5.5% CHO solution (L) immediately prior t=
o the start of the run and 2 ml kg(-1) body weight every 5 km thereafter.=
The total volume of fluid ingested [mean (SEM)] was 1112 (42), 1116 (44)=
and 1100 (44) ml, respectively. Running times for W, O and L trials were=
193.9 (5.0), 192.4 (3.3) and 190.0 (3.9) min, respectively. Performance =
time for the L trial was faster (P < 0.05) compared with that of the W tr=
ial. Running speed was maintained in the L trial. Whereas it decreased af=
ter 10 km (P < 0.05) in the W and after 25 km (P < 0.05) in the O trial. =
Blood glucose and lactate, and hormonal responses to fluid ingestion were=
similar in all three trials. Higher plasma free fatty acid and glycerol =
concentrations were observed at the end of the W trial compared with thos=
e obtained after the O and L trials, respectively (P < 0.05). Plasma ammo=
nia concentration was higher (P < 0.01) at the end of the L trial compare=
d with the W trial. Plasma creatine kinase concentration was higher (P < =
0.05) 24 h after the completion of the L trial than after the W trial. Th=
is study shows that the ingestion of a 5.5% CHO solution improves maratho=
n running performance.
=0D
Authors PR Below, R Morarodriguez, J Gonzalezalonso, EF Coyle
Title Fluid and Carbohydrate Ingestion Independently Improve Performance =
During 1-H of Intense Exercise
Full source Medicine and Science in Sports and Exercise, 1995, Vol 27, Is=
s 2, pp 200-210
Author keywords Dehydration; Hyperthermia; Physical Performance; Cardiova=
scular; Plasma Volume
KeyWords Plus CARDIOVASCULAR DRIFT; GLUCOSE-INFUSION; HEAT; REPLACEMENT; =
ELECTROLYTE; ENDURANCE; FEEDINGS; BLOOD; DEHYDRATION; METABOLISM
TGA/Book No. QF640
Discipline Sports Science & Medicine
Document type Article
Language English
Address Coyle EF, Univ Texas, Dept Kinesiol & Hlth Educ, Human Performanc=
e Lab, Austin,TX 78712 USA
ISBN/ISSN 0195-9131
Publisher Williams & Wilkins, 351 West Camden St, Baltimore, MD 21201-243=
6
Abstract This study determined the effects of fluid and carbohydrate inge=
stion on performance, core temperature, and cardiovascular responses duri=
ng intense exercise lasting 1 h. On four occasions, eight men cycled at 8=
0 +/- 1% (+/-SEM) of VO2max for 50 min followed by a performance test. Du=
ring exercise, they consumed either a large volume (1330 +/- 60 ml) of a =
6% carbohydrate (79 +/- 4 g) solution or water or a small volume (200 +/-=
10 ml) of a 40% maltodextrin (79 +/- 4 g) solution or water. These trial=
s were pooled so the effects of fluid replacement (Large FR vs Small FR) =
and carbohydrate ingestion (CHO vs NO CHO) could be determined. Performan=
ce times were 6.5% faster during Large FR than Small FR and 6.3% faster d=
uring CHO than NO CHO (P < 0.05). At 50 min, heart rate was 4 +/- 1 b.min=
(-1) lower and esophageal temperature was 0.33 +/- 0.04 degrees C lower d=
uring Large FR than Small FR (P < 0.05) but no differences occurred betwe=
en CHO and NO CHO. In summary, Large FR slightly attenuates the increase =
in heart rate and core temperature which occurs during Small FR. Both flu=
id and carbohydrate ingestion equally improve cycling performance and the=
ir effects are additive.
=0D
Authors DPM Maclaren, T Reilly, IT Campbell, KN Frayn
Title Hormonal and Metabolite Responses to Glucose and Maltodextrin Inges=
tion with or Without the Addition of Guar Gum
Full source International Journal of Sports Medicine, 1994, Vol 15, Iss 8=
, pp 466-471
Author keywords Carbohydrates; Hormones; Metabolism; Guar Gum
KeyWords Plus MUSCLE GLYCOGEN UTILIZATION; PROLONGED EXERCISE; CARBOHYDRA=
TE INGESTION; PERFORMANCE; OXIDATION; FEEDINGS; PLASMA; ABSORPTION; FRUCT=
OSE; FATIGUE
TGA/Book No. PV659
Discipline Sports Science & Medicine
Document type Article
Language English
Address Maclaren DPM, Liverpool John Moores Univ, Sch Human Sci, Mountfor=
d Bldg, Byrom St, Liverpool L3 3AF, Merseyside, ENGLAND
ISBN/ISSN 0172-4622
Publisher Georg Thieme Verlag, P O Box 30 11 20, D-70451 Stuttgart, Germa=
ny
Abstract The purpose of this study was to examine the effects of ingestin=
g water (P), a glucose solution (GL), a maltodextrin solution (Md), a glu=
cose solution with 8% guar gum (GL + G), and a maltodextrin solution with=
8% guar gum (Md + G), on the hormonal and metabolite responses during cy=
cling, and on subsequent time to exhaustion. Five male subjects undertook=
five 90 min rides on a bicycle ergometer at an exercise intensity corres=
ponding to 65% VO(2)max after having ingested 1 g.kg(-1) body weight of t=
he test product in 400 ml of water immediately before the exercise. Blood=
samples were taken during the trials for analyses of adrenaline, noradre=
naline, insulin, glucagon, glucose, lactate and non-esterified fatty acid=
s (NEFA). Respiratory measures were also undertaken during the trials for=
the determination of oxygen consumption (VO2) and respiratory exchange r=
atio (RER), from which the carbohydrate oxidation rates were calculated. =
Rates of perceived exertion (RPE) were also assessed. Ten minutes after t=
he 90 min ride, subjects exercised to volitional exhaustion at an exercis=
e intensity of 75% VO(2)max. ANOVA revealed that there were significant d=
ifferences between the treatments for adrenaline (p<0.01), insulin (p<0.0=
5), glucose (p<0.01), lactate (p<0.01), NEFA (p<0.01), RER (p<0.001) and =
carbohydrate oxidation rate (p<0.01). Post hoc analyses showed that signi=
ficantly higher levels of adrenaline were found for P compared to Md (p<0=
=2E05), significantly lower levels of insulin for P compared to Md (p<0.0=
5), significantly lower levels of glucose and lactate for P compared to a=
ll carbohydrate treatments (p<0.05), significantly higher levels of NEFA =
for P compared to the carbohydrate treatments (p<0.05), and significantly=
lower RER and carbohydrate oxidation rates for P compared to the carbohy=
drate trials (p<0.05). Furthermore, tests highlighted that significantly =
longer times to exhaustion were achieved by the carbohydrate treatments c=
ompared to placebo (p<0.05). These results support the use of carbohydrat=
e supplementation prior to prolonged exercise, although the type of carbo=
hydrate is not important.
=0D
Authors ME Langenfeld, JG Seifert, SR Rudge, RJ Bucher
Title Effect of Carbohydrate Ingestion on Performance of Nonfasted Cyclis=
ts During a Simulated 80-Mile Time Trial
Full source Journal of Sports Medicine and Physical Fitness, 1994, Vol 34=
, Iss 3, pp 263-270
Author keywords Bicycling; Carbohydrate Metabolism; Diet
TGA/Book No. PW243
Discipline Sports Science & Medicine
Document type Article
Language English
Address Langenfeld ME, Miami Univ, Dept Family & Consumer Sci, Oxford,OH =
45056 USA
ISBN/ISSN 0022-4707
Publisher Edizioni Minerva Medica, Corso Bramante 83-85, Int Journals Dep=
t., 10126 Turin, Italy
Abstract The purpose of this study was to determine the effect of carbohy=
drate supplementation on finishing time of a realistically simulated 80 m=
ile bicycle time trial. Fourteen trained cyclists pedalled at self-selec=
ted pace on their own bicycles on windload simulators. Two trials were p=
erformed one week apart. Each trial was preceded by two days of prescrib=
ed diet, with a final feeding 3-4 prior to exercise. Following each 10 m=
ile segment, subjects ingested either a non-caloric placebo (PL) or the c=
arbohydrate maltodextrin supplement (MD; 5% maltodextrin +2% fructose) at=
dosage of 0.25 g.kg-1 body weight (mean intake rate, total: 37 g.h-1, 1=
48 g) in a double blind, counter-balanced design. Mean (+/-SEM) finishin=
g times were faster by 5% with MD (241.0 +/- 2.1 minutes versus 253.2 +/-=
2.1 minutes), p < 0.05. With MD, serum glucose levels rose sharply afte=
r 40 miles and were significantly higher than PL (p < 0.05). Final gluco=
se values were 6.0 +/- 0.2 mmol.l-1 and 4.1 +/- 0.2 mmol.l-1 for MD and P=
L, respectively. With MD, free fatty acid levels were significantly lowe=
r (p < 0.05), and riders sustained higher average intensity over the enti=
re distance. At the finish, intensities were 64.7 +/- 1.9 %VO2max and 55=
=2E3 +/- 1.9 %VO2max for GP and PL, respectively. Mean carbohydrate oxid=
ation was significantly higher (p < 0.05) for MD, 2.01 +/- 0.2 g.min-1 an=
d 1.64 +/- 0.2 g.min-1 for MD and PL, respectively. These data show that=
ingestion of MD, during ultraendurance exercise, in comparison to PL, de=
creases the time to finish a self-paced bicycle time trial.
=0D
Authors DW Bacharach, SP Vonduvillard, KW Rundell, J Meng, MR Cring, L Sz=
medra, JM Castle
Title Carbohydrate Drinks and Cycling Performance
Full source Journal of Sports Medicine and Physical Fitness, 1994, Vol 34=
, Iss 2, pp 161-168
Author keywords Carbohydrate; Lactate; Endurance
TGA/Book No. PJ655
Discipline Sports Science & Medicine
Document type Article
Language English
Address Vonduvillard SP, William Paterson Coll, Dept Exercise & Movement =
Sci, 300 Pompton Rd, Wayne,NJ 07470 USA
ISBN/ISSN 0022-4707
Publisher Edizioni Minerva Medica, Corso Bramante 83-85, Int Journals Dep=
t., 10126 Turin, Italy
Abstract We compared the effects of similarly tasting orange flavored dri=
nks containing 0% (P), 6.4% (E1), and 10% (E2) carbohydrate (CHO) using 1=
2 well-trained cyclists (VO2max =3D 5.0 l/min-1) on metabolic responses t=
o exercise (EX) and a sprint type performance ride (PR). Each subject com=
pleted 3 separate 2 h EX bouts at 65% VO2max followed by a PR identified =
as the time in sec to complete 500 revolutions at a constant belt resista=
nce of 29.4 N (ANOVA*). The CHO feedings or placebo of 3 ml/kg body weigh=
t were given double blind and counter-balanced at 0 min and every 20 min =
thereafter during EX. Blood samples were drawn and core temperature (T(r)=
) was recorded at 0, 30, 60, 90, and 120 min of EX and 1 min post PR. Blo=
od samples were analyzed for glucose (G) and lactate [LA-]. Blood G at 0 =
min were similar; however, at 120 min, G was 3.96 mM for P*, 4.57 mM for =
E1, and 4.77 mM for E2. Blood [LA-] remained similar throughout EX averag=
ing (P, 2.6 mM; E1, 2.9 mM; E2, 2.5 mM). Tr at 120 min was also similar (=
P, 38.5-degrees-C; E1, 38.6-degrees-C; E2, 38.3-degrees-C). Mean PR times=
for P(264.4 s)**, E1 (255.3 s)*, E2 (252.4 s)* indicate consumption of a=
CHO drink during EX improves PR. Furthermore, a 10% CHO drink improves P=
R more than a 6.4% CHO drink.
=0D
Authors JA Hawley, SC Dennis, TD Noakes
Title Carbohydrate, Fluid, and Electrolyte Requirements of the Soccer Pla=
yer - A Review
Full source International Journal of Sport Nutrition, 1994, Vol 4, Iss 3,=
pp 221-236
Author keywords Glucose; Glycogen; Potassium; Sodium; Sweat
TGA/Book No. PF026
Discipline Sports Science & Medicine
Document type Review
Language English
Address Hawley JA, Univ Cape Town, Sch Med, Med Res Council, Cape Town 79=
25, SOUTH AFRICA
ISBN/ISSN 1050-1606
Publisher Human Kinetics Publ Inc, 1607 N Market St, Box 5076, Champaign,=
IL 61820-5076
Abstract Soccer requires field players to exercise repetitively at high i=
ntensities for the duration of a game, which can result in marked muscle =
glycogen depletion and hypoglycemia. A soccer match places heavy demands =
on endogenous muscle and liver glycogen stores and fluid reserves, which =
must be rapidly replenished when players complete several matches within =
a brief period of time. Low concentrations of muscle glycogen have been r=
eported in soccer players before a game, and daily carbohydrate (CHO) int=
akes are often insufficient to replenish muscle glycogen stores. CHO supp=
lementation during soccer matches has been found to result in muscle glyc=
ogen sparing (39%), greater second-half running distances, and more goals=
being scored with less conceded, when compared to consumption of water. =
Thus, CHO supplementation has been recommended prior to, during, and afte=
r matches. In contrast, there is currently insufficient evidence to recom=
mend without reservation the addition of electrolytes to a beverage for i=
ngestion by players during a game resulting in sweat losses of <4% of bod=
y weight.
=0D
Authors S Saitoh, Y Tasaki, K Tagami, M Suzuki
Title Muscle Glycogen Repletion and Preexercise Glycogen-Content - Effect=
of Carbohydrate Loading in Rats Previously Fed a High-Fat Diet
Full source European Journal of Applied Physiology and Occupational Physi=
ology, 1994, Vol 68, Iss 6, pp 483-488
Author keywords Carbohydrate Loading; Glycogen Utilization; Glycogen Repl=
etion; Glycogen Synthase; Muscle; Rat
KeyWords Plus PROLONGED EXERCISE; SKELETAL-MUSCLE; LIVER; RESYNTHESIS; CO=
MPLEX; METABOLISM; DEPLETION; STORAGE
TGA/Book No. NU646
Discipline Sports Science & Medicine
Document type Article
Language English
Address Saitoh S, Univ Tsukuba, Inst Hlth & Sport Sci, Biochem Exercise &=
Nutr Lab, Tsukuba, Ibaraki 305, JAPAN
ISBN/ISSN 0301-5548
Publisher Springer Verlag, 175 Fifth Ave, New York, NY 10010
Abstract We have recently reported that rates of muscle glycogen repletio=
n during the early period of recovery were increased by carbohydrate (CHO=
) loading in rats previously fed a high fat diet. However, the reason for=
this remained unanswered. The purpose of this study was to examine wheth=
er an increase of glycogen utilization due to an elevated pre-exercise gl=
ycogen store would enhance rates of glycogen repletion in muscle. Despite=
an equal degree of glycogen depletion, the rates of glycogen repletion o=
f soleus, red and white gastrocnemius muscles by postexercise administrat=
ion of glucose (3.0 g.kg(-1) body mass) and citrate (0.5 g.kg(-1) body ma=
ss) were faster in the CHO loaded (3 days) rats than in the nonloaded rat=
s, as a result of elevated pre-exercise glycogen content and consequently=
the greater glycogen utilization. The higher rate of muscle glycogen rep=
letion may in part be explained by increased postexercise glycogen syntha=
se activity.
=0D
Authors JF Gautier, F Pirnay, B Jandrain, M Lacroix, F Mosora, AJ Scheen,=
G Cathelineau, PJ Lefebvre
Title Availability of Glucose Ingested During Muscle Exercise Performed U=
nder Acipimox-Induced Lipolysis Blockade
Full source European Journal of Applied Physiology and Occupational Physi=
ology, 1994, Vol 68, Iss 5, pp 406-412
Author keywords Acipimox; Exercise; Metabolism; Oral Glucose; Stable Isot=
opes
KeyWords Plus NATURALLY LABELED GLUCOSE-C-13; PROLONGED EXERCISE; METHODO=
LOGICAL CONSIDERATIONS; METABOLIC AVAILABILITY; CARBOHYDRATE FEEDINGS; EX=
OGENOUS GLUCOSE; HUMANS; C-13; OXIDATION; LOAD
TGA/Book No. NM257
Discipline Sports Science & Medicine
Document type Article
Language English
Address Lefebvre PJ, Chu Sart Tilman, Dept Med, B35, B-4000 Liege 1, BELG=
IUM
ISBN/ISSN 0301-5548
Publisher Springer Verlag, 175 Fifth Ave, New York, NY 10010
Abstract This study investigated the percentage of carbohydrate utilizati=
on than can be accounted for by glucose ingested during exercise performe=
d after the ingestion of the potent lipolysis inhibitor Acipimox. Six hea=
lthy male volunteers exercised for 3 h on a treadmill at about 45% of the=
ir maximal oxygen uptake, 75 min after having ingested 250 mg of Acipimox=
=2E After 15-min adaptation to exercise, they ingested either glucose dis=
solved in water, 50 g at time 0 min and 25 g at time 60 and 120 min (gluc=
ose, G) or sweetened water (control, C). Naturally labelled [C-13]glucose=
was used to follow the conversion of the ingested glucose to expired-air=
CO2. Acipimox inhibited lipolysis in a similar manner in both experiment=
al conditions. This was reflected by an almost complete suppression of th=
e exercise-induced increase in plasma free fatty acid and glycerol and by=
an almost constant rate of lipid oxidation. Total carbohydrate oxidation=
evaluated by indirect calorimetry, was similar in both experimental cond=
itions [C, 182, (SEM 21); G, 194 (SEM 16) g . 3 h(-1)], as was lipid oxid=
ation [C, 57 (SEM 6); G, 61 (SEM 3) g . 3 h(-1)]. Exogenous glucose oxida=
tion during exercise G, calculated by the changes in C-13 : C-12 ratio of=
expired air CO2, averaged 66 (SEM 5) g . 3 h(-1) (19% of the total energ=
y requirement). Consequently, endogenous carbohydrate utilization was sig=
nificantly smaller after glucose than after placebo ingestion: 128 (SEM 1=
8) versus 182 (SEM 21) g . 3 h(-1), respectively (P < 0.05). Symptoms of =
intense fatigue and leg cramps observed with intake of sweet placebo were=
absent with glucose ingestion. In conclusion, we found glucose ingestion=
during 3-h exercise with lipolysis blockade could provide metabolic subs=
trate permitting a significant Sparing of endogenous carbohydrate and con=
sequently an improvement in performance.
=0D
Authors AN Bosch, SC Dennis, TD Noakes
Title Influence of Carbohydrate Ingestion on Fuel Substrate Turnover and =
Oxidation During Prolonged Exercise
Full source Journal of Applied Physiology, 1994, Vol 76, Iss 6, pp 2364-2=
372
Author keywords Glucose Oxidation; Endogenous Glucose; Glycogen
KeyWords Plus HEPATIC GLUCOSE OUTPUT; STRENUOUS EXERCISE; MUSCLE GLYCOGEN=
; AVAILABILITY; FRUCTOSE; HUMANS; PERFORMANCE; EXCHANGE; FATIGUE; INSULIN=
TGA/Book No. NR916
Discipline Sports Science & Medicine
Document type Article
Language English
Address Bosch AN, Univ Cape Town, Sch Med, Ctr Sports Sci, Dept Physiol, =
Observ, Cape Town 7925, SOUTH AFRICA
ISBN/ISSN 8750-7587
Publisher Amer Physiological Soc, 9650 Rockville Pike, Bethesda, MD 20814=
Abstract This study examined effects of ingesting a 10% carbohydrate (CHO=
) drink (CI) or placebo (PI) at 500 ml/h on total (splanchnic) glucose ap=
pearance (endogenous + exogenous; Ra), blood glucose oxidation, and muscl=
e glycogen utilization in 14 male endurance-trained cyclists who rode for=
180 min at 70% of maximal O-2, uptake after CHO loading [starting muscle=
glycogen 203 +/- 7 (SE) mmol/kg wet wt]. Total CHO oxidation was similar=
in CI and PI, but Ra increased significantly during the trial in both gr=
oups, with CI reaching a plateau after 75 min. Pa was significantly great=
er in CI than in PI at the end of exercise. Blood glucose oxidation also =
increased significantly during the trial to a plateau in CI and was signi=
ficantly higher in CI than in PI at the end of exercise. However, mean en=
dogenous Ra was significantly lower in CI than in PI throughout exercise,=
as was oxidation of endogenous blood glucose, which remained almost cons=
tant in CI and reached 43 +/- 8 and 73 +/- 13 mu mol.min(-1).kg fat-free =
mass(-1) in CI and PI, respectively, at the end of exercise. At 0.83 g/mi=
n of CHO ingestion, 0.77 +/- 0.03 g/min was oxidized. Muscle glycogen uti=
lization was identical in both groups and was higher during the Ist h of =
exercise. We conclude that ingestion of a 10% CHO solution at 500 ml/h du=
ring prolonged exercise 1) had a marked liver glycogen-sparing effect and=
/or caused a reduction in gluconeogenesis that should ultimately extend e=
xercise time to exhaustion by delaying onset of hypoglycemia, 2) increase=
d blood glucose oxidation, 3) provided CHO at a rate closely matched by t=
he rate of oxidation of ingested CHO, and 4) did not have a muscle glycog=
en-sparing effect.
=0D
Authors M Hargreaves
Title Carbohydrate and Lipid Requirements of Soccer
Full source Journal of Sports Sciences, 1994, Vol 12, Sp. Iss., pp S13-S1=
6
Author keywords Free Fatty Acids; Metabolism; Muscle Glycogen; Triglyceri=
des
TGA/Book No. NQ193
Discipline Sports Science & Medicine
Document type Article
Language English
Address Hargreaves M, Univ Melbourne, Dept Physiol, Parkville, Vic 3052, =
AUSTRALIA
ISBN/ISSN 0264-0414
Publisher E & Fn Spon, 2-6 Boundary Row, London, United Kingdom SE1 8HN
Abstract Soccer involves high-intensity, intermittent exercise and places=
a heavy demand on the body's liver and muscle glycogen reserves. Thus, c=
arbohydrate depletion may contribute, in part, to fatigue and reduced per=
formance during a soccer match. In addition, fatty acids derived from bot=
h adipose tissue and intramuscular triglyceride stores will be utilized. =
Soccer players engaged in strenuous competition and training should be en=
couraged to consume a diet that is relatively high in carbohydrate (at le=
ast 55% of total energy intake). Furthermore, the inclusion of carbohydra=
te in beverages consumed during and after a soccer match is likely to enh=
ance performance and facilitate the recovery of liver and muscle glycogen=
reserves.
=0D
Authors JL Ventura, A Estruch, G Rodas, R Segura
Title Effect of Prior Ingestion of Glucose or Fructose on the Performance=
of Exercise of Intermediate Duration
Full source European Journal of Applied Physiology and Occupational Physi=
ology, 1994, Vol 68, Iss 4, pp 345-349
Author keywords Blood Glucose; Carbohydrates; Endurance
KeyWords Plus ENDURANCE PERFORMANCE; CARBOHYDRATE FEEDINGS; CYCLING PERFO=
RMANCE; PROLONGED EXERCISE; GLYCOGEN DEPLETION; INTENSITY; PLACEBO; USAGE=
TGA/Book No. NK872
Discipline Sports Science & Medicine
Document type Article
Language English
Address Ventura JL, Uci Hosp Princeps Espanya Csub, Feixa Llarga S-N, E-0=
8907 Lhospitalet Llobr, SPAIN
ISBN/ISSN 0301-5548
Publisher Springer Verlag, 175 Fifth Ave, New York, NY 10010
Abstract The metabolic responses induced by the ingestion of a beverage c=
ontaining glucose (G), fructose (F) or placebo (W) 30 min before exercise=
of high intensity and intermediate duration have been investigated; in t=
hese conditions the energy processes are mostly dependent on aerobic reac=
tions. A group of 11 male recreational sportsmen ran on a treadmill, at a=
n intensity corresponding to 82% of peak oxygen consumption, until exhaus=
tion on three different occasions (after ingestion of a beverage containi=
ng 75 g of G, 75 g of F or W). Plasma glucose, insulin, and lactic acid c=
oncentrations were determined just prior to the ingestion of the beverage=
s, 30 min afterwards and 10 and 30 min after completion of the exercise. =
The mean endurance time was 644 (SD 261) s after the ingestion of G, 611 =
(SD 227) s after the ingestion of F and 584 (SD 189) s after the ingestio=
n of the W (P<0.05 between G and W). No differences in the oxygen uptake,=
respiratory quotient or lactate concentrations between the three trials =
were observed. Both plasma glucose and insulin concentrations determined =
in samples obtained immediately before the onset of exercise were higher =
when G was ingested than when F (P<0.05 and P<0.05, respectively) or W (P=
<O.OO1 and P<0.005, respectively) were ingested. These findings would sug=
gest that the ingestion of G prior to an effort of intermediate duration =
may improve physical performance.
=0D
Authors GP Ganzit, CG Gribaudo, A Chiey, D Dellabetta, F Verzini
Title Effects of Ingestion of a Carbohydrate Beverage During a Strenuous =
and Middle-Prolonged Exercise
Full source Medicina Dello Sport, 1994, Vol 47, Iss 1, pp 27-36
Author keywords Exercise; Carbohydrate; Fluid Balance
TGA/Book No. NG456
Discipline Sports Science & Medicine
Document type Article
Language Italian
Address Ganzit GP, Fmsi Torino, CoNi, Ist Med Sport, Ctr Interuniv Studi =
& Ric Med Sport, Via Filadelfia 88, I-10134 Turin, ITALY
ISBN/ISSN 0025-7826
Publisher Edizioni Minerva Medica, Corso Bramante 83-85, Int Journals Dep=
t., 10126 Turin, Italy
Abstract The purpose of this study was to determine the effect of 10.1% c=
arbohydrate beverages intake, containing 51.8% of maltodextrin, 33.1% of =
fructose and 15.1% of glucose. Ten runners performed a 10000 m track test=
at 80% of their best seasonal time and suddenly a maximal treadmill test=
=2E The first treadmill workload was at a similar intensity (average hear=
t rate) than 1 0000 m track test and its duration was 5 min, the second w=
orkload, of the same duration, was at a intensity of 5% higher. The third=
and final workload was prolonged to subject exhaustion and the workload =
was 5% higher than the second workload. Total duration, 10000 track test =
and treadmill test, was about 50 min. Before the session and 3 min after =
the end of treadmill test a blood sample from antecubital vein was taken =
to determine haemochromocytometric parameters, NEFA, lactate and blood gl=
ucose levels. Another blood sample was taken at the end of 10000 track te=
st to determine only NEFA, lactate and blood glucose levels. During the t=
est the runners ingested 200 ml of an hypocaloric placebo (PLC) or of a c=
arbohydrate solution (MDX) for three times: at the start, after 5000 m an=
d at the end of 10000 m track test. They totally ingested 600 ml of water=
and in the MDX session they also ingested 60.7 g of carbohydrate. There =
were no significant difference between the two session for weight losses =
and haemochromocytometric values. The subjects performed the 1 0000 m tra=
ck test in the two sessions with no significant differences in total time=
and average heart rate. In MDX session, the subjects performed a treadmi=
ll test for a significant longer time (876 sec vs 792 sec) with a RER (1.=
02 vs 0.99) and VCO2 higher at maximal workload. After the 10000 track te=
st and after treadmill test, in MDX session, NEFA value was significant l=
ower, blood glucose was significant higher than in PLC session. Moreover =
final blood lactate was significant higher after MDX session than PLC ses=
sion (7.4 mmol-1 and 6.5 mmol-1). We observed a similar hydric absorption=
with MDX and PLC and the important weight losses during the test suggest=
s the utility of an hydric-integration also in less than an hour exercise=
s. The ideal integrator is a carbohydrate beverage. The greater availabil=
ity of glucose with this beverage enhanced the performance for a muscular=
glycogen sparing or for a more important blood glucose utilisation. Duri=
ng intense exercise, as in this test, the greater availability of glucose=
allows a greater involving of the anaerobic metabolism as demonstrate by=
the higher RER, VCO2 and lactate final values in MDX session.
=0D
Authors DG Jenkins, J Palmer, D Spillman
Title The Influence of Dietary Carbohydrate on Performance of Supramaxima=
l Intermittent Exercise
Full source European Journal of Applied Physiology and Occupational Physi=
ology, 1993, Vol 67, Iss 4, pp 309-314
Author keywords Supramaximal Exercise; Dietary Carbohydrate
KeyWords Plus MUSCLE; METABOLISM
TGA/Book No. MF072
Discipline Sports Science & Medicine
Document type Article
Language English
Address Jenkins DG, Univ Queensland, Dept Human Movement Studies, Human P=
erformance Lab, Brisbane 4072, AUSTRALIA
ISBN/ISSN 0301-5548
Publisher Springer Verlag, 175 Fifth Ave, New York, NY 10010
Abstract The present investigation examined the influence of dietary carb=
ohydrate (CHO) on the performance of supramaximal intermittent exercise. =
A group of 14 moderately trained male students [mean age 21.0 (SD 1.6) ye=
ars] completed a maximal oxygen consumption test and two identical 'maxim=
al interval tests' (MIT1 and MIT2) over a 10-day experimental period. Eac=
h MIT involved five 60-s all-out periods of cycling (against 0.736 N . Kg=
-1 body mass), with each period separated by 5 min of passive recovery. A=
ll subjects consumed a moderate CHO diet for 3 days preceding MIT1 (55.3%=
of energy intake as CHO) and were then randomly assigned to either a hig=
h CHO (83%), moderate CHO (58%) or low CHO (12%) diet for the 3 days sepa=
rating MIT1 and MIT2. All food and drink consumed during the experimental=
period was weighed and recorded for later dietary analysis. Measurements=
of work done, exercise oxygen consumption (VO2), venous blood pH, plasma=
lactate and plasma glucose concentrations were compared between interval=
tests. Independent Student's t-tests revealed that the 5.6% increase in =
total work done recorded by the high CHO group and the 2.3% increase by t=
he moderate CHO group between MIT1 and MIT2, were significantly different=
to the 5.4% decrease in performance recorded for the low CHO group (P<0.=
001 and P<0.01, respectively). No significant differences in performance =
changes was found between the high and moderate CHO groups; 10 subjects i=
n each of these groups would have been necessary to attain significance a=
t the 0.05 level using the same procedures. No changes in VO2, venous blo=
od pH, plasma lactate or glucose concentrations were found among the grou=
ps. These data showed that when compared to a low CHO diet, a moderate/hi=
gh intake of dietary CHO could at least maintain the performance of supra=
maximal intermittent exercise. The results emphasise the importance of di=
etary CHO for athletes whose activities involve repeated periods of very =
high intensity exercise.
=0D
Authors BB Yaspelkis, JG Patterson, PA Anderla, Z Ding, JL Ivy
Title Carbohydrate Supplementation Spares Muscle Glycogen During Variable=
-Intensity Exercise
Full source Journal of Applied Physiology, 1993, Vol 75, Iss 4, pp 1477-1=
485
Author keywords Exercise Performance; Glucose; Insulin; Carbohydrate Oxid=
ation; Maltodextrin; Fructose
KeyWords Plus PROLONGED STRENUOUS EXERCISE; INGESTION; GLUCOSE; PERFORMAN=
CE; METABOLISM; FEEDINGS; RATS
TGA/Book No. MD352
Discipline Sports Science & Medicine
Document type Article
Language English
Address Ivy JL, Univ Texas, Dept Kinesiol, Exercise Physiol & Metab Lab, =
Bellmont Hall 222, Austin,TX 78712 USA
ISBN/ISSN 8750-7587
Publisher Amer Physiological Soc, 9650 Rockville Pike, Bethesda, MD 20814=
Abstract Effects of carbohydrate (CHO) supplementation on muscle glycogen=
utilization and endurance were evaluated in seven well-trained male cycl=
ists during continuous cycling exercise that varied between low [45% maxi=
mal O2 uptake (Vo2 max)] and moderate intensity (75% Vo2 max). During eac=
h exercise bout the subjects received either artificially flavored placeb=
o (P), 10% liquid CHO supplement (L; 3 X 18 g CHO/h), or solid CHO supple=
ment (S; 2 X 25 g CHO/h). Muscle biopsies were taken from vastus laterali=
s during P and L trials immediately before exercise and after first (124 =
min) and second set (190 min) of intervals. Subjects then rode to fatigue=
at 80% Vo2 max. Plasma glucose and insulin responses during L treatment =
reached levels of 6.7 +/- 0.7 mM and 70.6 +/- 17.2 muU/ml, respectively, =
and were significantly greater than those of P treatment (4.4 +/- 0.1 mM =
and 17.7 +/- 1.6 muU/ml) throughout the exercise bout. Plasma glucose and=
insulin responses of S treatment were intermediate to those of L and P t=
reatments. Times to fatigue for S (223.9 +/- 3.5 min) and L (233.4 +/- 7.=
5 min) treatments did not differ but were significantly greater than that=
of P treatment (202.4 +/- 9.8 min). After the first 190 min of exercise,=
muscle glycogen was significantly greater during L (79 +/- 3.5 mumol/g w=
et wt) than during P treatment (58.5 +/- 7.2 mumol/g wet wt). Furthermore=
, differences in muscle glycogen concentrations between L and P treatment=
s after 190 min of exercise and in time to fatigue for these treatments w=
ere positively related (r =3D 0.76, P < 0.05). These results suggest that=
CHO supplementation can enhance prolonged continuous variable-intensity =
exercise by reducing dependency on muscle glycogen as a fuel source.
=0D
Authors MJ Obrien, CA Viguie, RS Mazzeo, GA Brooks
Title Carbohydrate Dependence During Marathon Running
Full source Medicine and Science in Sports and Exercise, 1993, Vol 25, Is=
s 9, pp 1009-1017
Author keywords Glucose; Lactate; Fatty Acids; Epinephrine; Insulin; Ener=
gy Expenditure; Lactate Shuttle; Glucose Fatty Acid Cycle; Exertion
KeyWords Plus LACTATE PRODUCTION; SKELETAL-MUSCLE; EXERCISE; GLUCOSE; MET=
ABOLISM; ACCLIMATIZATION; CLEARANCE; DISTANCE; RUNNERS; HUMANS
TGA/Book No. LW384
Discipline Sports Science & Medicine
Document type Article
Language English
Address Brooks GA, Univ Calif Berkeley, Dept Human Biodynam, Exercise Phy=
siol Lab, 103 Harmon Gymnasium, Berkeley,CA 94720 USA
ISBN/ISSN 0195-9131
Publisher Williams & Wilkins, 428 E Preston St, Baltimore, MD 21202
Abstract To test the hypothesis that marathon running is dependent on lip=
id oxidation, 12 post-absorptive males (31.9 +/- 2.1 yr) ran a treadmill =
marathon and substrate utilization was assessed. Subjects were placed int=
o a fast (F less-than-or-equal-to 2 hr, 45 min; 73.3% VO2max), or a slow =
(S less-than-or-equal-to 3 hr, 45 min; 64.5% VO2max) Marathon group. The =
day before testing subjects rested, but ate their normal diet. Subjects w=
ere tested in the morning after an overnight fast, and only tap water, at=
a rate of 1 l.h, was ingested during exercise. Blood glucose concentrati=
on rose at exercise onset, peaked at approximately an hour, but then decr=
eased over time remaining at or above resting levels. Free fatty acids an=
d glycerol rose continuously. No significant differences in plasma FFA, g=
lycerol, or blood glucose concentrations were observed between F or S gro=
ups during the marathon. Mean blood lactate concentration was significant=
ly higher (P < 0.05) in the F (2.1 +/- 0.3 mM) group than the S (1.2 +/- =
0.2 mM) during exercise. Mean plasma epinephrine was significantly higher=
in the F (0.9 +/- 0.2 ng.ml-1) than the S (0.6 +/- 0.2 ng.ml-1) group; n=
orepinephrine was also higher in F (3.9 +/- 1.4 ng. Ml 1) than the S (2.5=
+/- 0.9 ng.ml-1, P less-than-or-equal-to 0.05). Blood lactate and epinep=
hrine concentrations correlated significantly (r =3D 0.76 and 0.78 in F a=
nd S groups, respectively). The average respiratory gas exchange ratio (R=
=3D VCO2/VO2) was higher in F (0.99 +/- 0.01) than S (0.90 +/- 0.01, P l=
ess-than-or-equal-to 0.05). A direct relationship between carbohydrate ox=
idation and running speed during marathon running is indicated. Estimated=
carbohydrate combustion [(F: 2,414.3 +/- 43.0 kcal (575 +/- 10 g); S: 2,=
890.0 +/- 159.0 kcal (688 +/- 38 g)] exceeded estimated glycogen stores i=
n active muscle and liver (475 g =3D 375 g (muscle) + 100 g (liver)]. The=
refore, total body glycogen stores were made available for combustion. Al=
l classes of energy substrates participate, but carbohydrate, not lipid, =
is the primary fuel for marathon running.
=0D
Authors K Tsintzas, R Liu, C Williams, I Campbell, G Gaitanos
Title The Effect of Carbohydrate Ingestion on Performance During a 30-km =
Race
Full source International Journal of Sport Nutrition, 1993, Vol 3, Iss 2,=
pp 127-139
Author keywords Running; Endurance; Fluid Intake; Fatigue
TGA/Book No. LD693
Discipline Sports Science & Medicine
Document type Article
Language English
Address Williams C, Loughborough Univ Technol, Dept Phys Educ Sports Sci =
& Recreat Management, Loughborough LE11 3TU, Leics, ENGLAND
ISBN/ISSN 1050-1606
Publisher Human Kinetics Publ Inc, 1607 N Market St, Champaign, IL 61820-=
2200
Abstract Seven experienced endurance runners completed a 30-km road race =
on two occasions separated by 10 days. On each occasion the subjects cons=
umed 250 ml of either a 5% carbohydrate (CHO) solution or nonflavored tap=
water (W) immediately prior to the start of the race. And 150 ml of the =
assigned fluid every 5 km thereafter. Performance time for the CHO trial =
was faster compared with the time recorded for the W trial ( 128.3 +/- 19=
=2E9 min vs. 131.2 +/- 18.7 min [p<0.01] respectively). Running speed was=
maintained throughout the race in the CHO trial, whereas a decrease in t=
he running speed occurred after 25 km (p<0.05) in the W trial. No differe=
nce was found between the two trials in blood glucose concentration. Plas=
ma electrolyte concentrations, body weight loss, change in plasma volume,=
and rating of perceived exertion. Blood lactate concentration was higher=
at 25 km during the CHO trial compared with the W trial (p<0.01), but pl=
asma FFA and glycerol concentrations were lower at 30 km during the CHO t=
rial than during the W trial (p<0.05). In conclusion, this study shows th=
at performance time for a 30-km road race is improved after ingesting a 5=
% CHO solution.
=0D
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