ch10 - nutrition strategies for maximizing performance
No description yet. This curated deck is ready for daily study.
Card preview (24)
high vs low GI carbs precompetition?
doesn’t matter
an athlete is worried about insulin/blood sugar variation for consuming carbs. why is this misguided?
blood sugar levels typically return to normal within approximately 20 minutes, and the initial drop in blood sugar has no negative effect on performance
most important meal for aerobic endurance athletes?
precompetition meal because blood sugar levels are low and liver glycogen stores are substantially reduced
carb benefits from sports drink vs meal?
high carb meal preexercise: 9%. high-carb meal plus sports drink preexercise: 22%.
risk of not consuming carbs?
endurance athletes who are not chronically adapted to a low-carbohydrate diet and start exercise with depleted glycogen stores will break down muscle to use protein for energy and may acutely suppress immune and central nervous system functioning
downside of low glycogen stores?
may suppress immune and central nervous system functioning
benefit of prehydrating several hours before exercise?
to allow for fluid absorption and urine output. their urine specific gravity (USG) reading should be <1.02
people who may want to consider eating 4 hours before competition?
(1) athletes who get nauseated easily (2) experience diarrhea during competition (3) who get jitters (4) who compete in high intensity sports
common carb loading regimen?
three days of a high-carbohydrate diet in concert with tapering exercise the week before competition and complete rest the day before the event. “diet should provide adequate calories and carbohydrate per day: 8 to 10 g of carbohydrate per kg. this regimen should increase muscle glycogen stores 20% to 40% above normal.”
carb loading?
effective in men, but mixed in women; only high carb + surplus increases glycogen storage
athletes at risk of glycogen deficiency?
women who habitually consume less than 2,400 calories per day; may need to increase calories above this
side effects of types of carb loading?
oligosaccharides, which are found in dry beans and peas, onions, and foods with added inulin or other oligosaccharides, are rapidly fermented by bacteria in the gut, which can lead to excessive intestinal gas and bloating
optimal sport drink?
20 to 30 mEq of sodium (460-690 mg with chloride as the anion) per liter, 2 to 5 mEq of potassium (78-195 mg) per liter, and carbohydrate in a concentration of 5% to 10% but probably 6-8% (above 8% = delays gastric emptying)
fluid per hour for tennis players?
200 to 400 ml (6.8-13.5 ounces) per changeover (switching sides)
how does low glycogen stores affect training?
starting with already low carbohydrate stores will increase muscle breakdown
what are the two phases of glycogen synthesis?
(1) independent of insulin and lasts 30 to 60 minutes, and glycogen synthesis occurs rapidly (2) lasts several hours, and glycogen synthesis occurs at a much slower pace
when does glycogen synthesis occur?
when large amounts of carbohydrate, 1.0 to 1.85 g per kilogram body weight per hour, are consumed immediately after exercise or competition and at regular intervals every 15 to 60 minutes thereafter for up to 5 hours
how can athletes who eat lots of carbs attenuate muscle damage from marathons?
marathons lead to delayed glycogen resynthesis even if an athlete consumes a higher carbohydrate diet, possibly due to either metabolic disturbance or mechanical damage to muscle cells”
how does time between training affect carb intake?
athletes with >24hr to recover: can likely wait before eating after exercise and replace glycogen over 24hr period, athletes who train 2x/3x day: eat high carb meal immediately after event to replenish glycogen
can protein increase rate of glycogen storage?
yes, if carbohydrate intake is inadequate (i.e., <1.2 g of carbohydrate per kilogram body weight per hour)
carb intake to reduce muscle protein breakdown?
somewhere between 30 and 100g
main factor for muscle protein synthesis?
leucine content of protein and potentially speed of leucine delivery
when does maximal protein stimulation occur?
20 to 25 g (8.5 to 10 g of essential amino acids) of a high-quality, high-leucine, fast protein in younger people, 40g or more may be necessary in older adults
exercise interference?
concept: endurance exercise combined with strength training (back-to-back sessions) blunts gains in strength compared to strength training alone but results in improvements in endurance performance