carbs and heart rate

["guest@endurance.net" <guest@endurance.net>]

Beth Glace winorpin@aol.com
Hi Mike,
heart rate will be higher after meals.  Typically, the more calories provided the more the heart rate will go up.  Extra work must be done in order to digest the food, thus adding a little extra work for the heart.  In addition, high carb intakes cause extra CO2 to be produced, which has to be blown off.  Respiratory rate, then, will also increase.  This also adds a little more work to the heart.  The does not mean that adding carbs won't extend performance, but it does mean you may see a higher HR.
BTW, added fat will also result in elevated HRs.  I recently completed a study which evaluated the effect of aroma [as in aroma therapy] on perceived exertion and HR. We tried to test everyone at the same time of day, and to ask them to refrain from eating for a few hours before testing. One woman came in for her 2nd or 3rd testing session and had rates a good 10-15 beats higher during exercise than she had had previously.  Work load was the same during all tests.  I asked what she'd done differently, and she admitted to eating a very high fat meal, a with french fries, about an hour before exercise.  We had to reschedule her test for another day.  Big meals will elevate heart rate, and maybe by giving carbs, you are just getting more total calories into the horse. 
Beth Glace, MS CDN
Sports Nutritionist,Research Assoc.
Lenox Hill Hospital   NY, NY