As a sports dietitian, I rely on the
research of exercise physiologists and sports scientists who study the best
ways for competitive athletes to fuel their bodies to optimize their
performance. John Ivy PhD, Professor Emeritus at the University of Texas-Austin
and author of Nutrient Timing, is one
such researcher. Here are some of his insights.
- Endurance athletes need
three times more carbs than protein to optimally fuel their muscles. If you are
on a high protein (or high fat) diet, you could easily be missing that goal.
Poorly fueled muscles have a higher risk of becoming damaged during exercise.
- Eating every 2-3 hours is best. Let's say you are an
Ironman triathlete who is training hard day after day. To optimally fuel your
muscles on a daily basis, research indicates you want to consume at least
2.5-3.5 grams carbohydrate/lb. (6-8 g/kg) body weight/day, spread evenly
throughout the day. That means carb-rich grains, fruits & veggies every 2-3
hours. This naturally happens if you eat breakfast, morning snack, lunch,
afternoon snack, dinner, and evening snack.
- Consuming carbohydrate
stimulates the release of insulin. Insulin regulates the amount of glucose
(sugar) in blood and allows the blood glucose to get into muscles to fuel
muscles and replenish depleted muscle glycogen. Insulin also blocks the breakdown
of muscle. (That's why people, before being diagnosed with Type I diabetes,
experience a lot of muscle loss.)
- Protein combined with
carbs stimulates a higher insulin response than eating just carbohydrate alone.
This means, after you exercise, recovering with chocolate milk will replace
glycogen more efficiently and better refuel your depleted muscles than if you
were to have a Gatorade.
- Fueling at half-time offers
an energy advantage. Soccer or football players would be wise to consume a
carb-protein beverage, as tolerated, during half-time. Toss a few 8-ounce lowfat
chocolate milk boxes into your gym bag?
- After an exhausting
workout, a 155-lb (70 kg) athlete should consume about 450 calories of recovery
food. The ideal target is 25-30 grams protein + ~85 grams carb as soon as
tolerable. (More precisely 0.2 g protein + 0.6 g carb/lb. (0.4 g P + 1.2 g C/kg)
body weight.) This could be a fruit smoothie (8 ounces of Greek yogurt + banana
+ berries) or 1 cup of cottage cheese + ½ cup granola + canned peaches. Food
labels can help you figure out winning combinations of foods. (Don't get
obsessed about the exact ratio; pay more attention to the concept of consuming more
calories from carbs than from protein.)
- To get the most out of
your weight-lifting program, you want to surround your workout with food. In a
13-week training program, one group consumed carbs + protein before and after
the workout, while another group ate the same food but at the start and end of
the day. The group that ate food close to their workout had a better training
response and at the end of the 13-week training period, they were able to lift
heavier weights (bench press, squat, dead lift).
- Choose carbs plus protein after hard exercise. By choosing both carbs+
protein (oatmeal + eggs, or pasta + meat sauce), you will be able to exercise
better 24 and 48 hours after hard muscle-damaging exercise. You'll have a lower
blood level of creatine kinase (CK), a marker of muscle damage.
- Post-exercise protein
activates mTOR, an enzyme that turns on muscle-building pathways. While protein
helps build muscles, carbs refuel muscles; so again, you want to eat some sort
of carb-protein combination at meals and snacks. Doing so helps sustain a rapid
rate of recovery for 8 hours.
- About 20 grams of
post-exercise protein is optimal to stimulate muscle growth. It's more protein
than many morning-exercisers might consume. For example, if you generally eat
just a bowl of oatmeal after your morning workout, your might want to cook the
oatmeal in milk and add two hardboiled eggs to the meal. Or if you have just a
salad after a lunchtime run, top it with tuna fish.
- A before-bed snack helps muscle growth. At night, growth
hormone peaks between 10:00 PM and 2:00 AM (the same time kids have growth
spurts). You want to take advantage of elevated growth hormone by providing
your muscles with the tools they need to grow. This means, before bed, eat a snack
with protein, such as cottage cheese, turkey roll-ups, or 3-4 ounces of
leftover chicken. (But please, don't even think about getting up in the middle
of the night to eat. Sleep is more important!)
- A bedtime snack helps maintain blood glucose levels. In the early hours of
the morning (4:00 AM) when blood glucose is sinking, another hormone, cortisol,
triggers muscles to break down into amino acids (the building blocks of
protein). These amino acids then get converted into glucose by the liver and
normalize blood glucose levels so the brain has fuel to function. A bedtime
snack can help maintain normal blood glucose levels overnight.
- Don't exercise on empty
in the morning; you want to break the fast! When you awaken in the morning,
your cortisol levels are elevated and breaking down muscle. If you eat nothing
before your morning workout, and/or skip breakfast afterwards, you stay in a
catabolic (muscle-loss) state. Bad idea! A pre-workout snack, such as a banana,
granola bar or swig of orange juice can switch your body from being in the muscle
breakdown mode to the muscle-building mode. (Note: Elevated cortisol can also
lead to abdominal adiposity. Yikes?)
- Protein-pacing helps reduce muscle loss at you age. By the time the average
(non-athletic) 20 year-old is age 70, he or she has lost about 40% of his/her
muscle mass; the rate of decline is about 6% per decade. Muscle power starts to
decline about age 30; strength at about age 40. By lifting weights, you can
curb that loss; use it or lose it! To reduce muscle loss, do "protein pacing" -
eating protein evenly throughout the day. This is preferable to having a big
chunk of protein just at dinner.
The bottom line: Food
works! To optimize your performance, 1) pay attention to what and when you eat
and 2) choose carb-protein combinations, with more carbs than protein. A sports
dietitian can help you create a winning food plan. Use the referral network at
SCANdpg.org to find your local expert.
Sports nutritionist Nancy Clark MS RD CSSD is a longtime MomsTEAM nutrition expert with a
private practice in the Boston-area
(Newton; 617-795-1875), where she helps
both fitness exercisers and competitive athletes create winning food plans. Her
best-selling Sports Nutrition Guidebook,
and food guides for marathoners, cyclists and soccer are available at nancyclarkrd.com. For information about
her online workshop with John Ivy, see www.NutritionSportsExerciseCEUs.com.
Teaser title:
The Science of Fueling for Performance
Teaser text:
Sports dietitian Nancy Clark relies on the research of exercise physiologists and sports scientists who study the best ways for competitive athletes to fuel their bodies to optimize their performance. Here are some of insights of one of the researchers she follows.