Summer Sports Nutrition
by Joyce Dewon
June 18, 2004
If you're hooked on exercise
you're probably just as hooked on using top-notch equipment
when you work out. Those who are serious about staying in
shape buy the best running shoes, carefully pick out the
best bikes and tread on durable treadmills. But do you pay
just as much attention to your nutrition?
Scientists who have studied exercise have found that what
you eat before, during and after workouts is crucial to
maintaining your health, getting into shape and staying fit.
To achieve your best athletic performance without getting
injured or sick depends on optimum nutrition. When you
carefully plan what to feed your exercised body, it rewards
you by feeling and looking better.
Short 'n Sweet
If you thought long exercise sessions were the only ways to
get decent exercise benefits, take notice: small doses of
exercise during the week can go a long way. " The important
thing, apparently, is just do it," says Howard D. Sesso,
ScD, author of an American Heart Association study on
exercise and heart disease. In his study, exercisers
demonstrated that several short sessions of exercise were as
good for the body as a single long session (Circ 8/00;
102:975-80). " Short sessions lasting 15 minutes long appear
to be helpful,"Dr. Sesso explains. Even walking about three
miles per week, which is a moderate level of exercise,
lowers your risk of heart disease by 10%.
Some people glorify in working up a sweat; others curse the
dampness. But putting in extra effort in even short bursts
of activity pays off: experts have found that intense
exercise burns more calories than more relaxed sessions,
more effectively reduces your risk of cardiovascular disease
and helps stabilize blood sugar levels. In addition, it
stimulates production of human growth hormone, which offsets
some of the effects of aging (Exp Biol Med 2004 Mar;
But don't go crazy if you haven't worked out in a long time.
The intensity of the workout should match your physical
According to the American Heart Association, when people
exercise at a comfortable pace, their heart rate and level
of exertion stay within a safe range, but still high enough
to benefit their health. Strenuous activities, for those who
can handle them, produce the most physiological bang for the
jog. But brisk walking within your own level of fitness
still offers significant benefits.
Feeding Your Muscles
When you exercise, you work and develop your muscles, which
are made primarily out of protein. Despite this fact, many
exercise experts have advocated high-carb diets for
athletes. But, as John Ivy, PhD, and Robert Portman, PhD,
point out in their book The Performance Zone (Basic Health),
"[While] there is no doubt that aerobic athletes require
more carbohydrate than strength athletes...we are now
discovering that the addition of protein to a carbohydrate
supplement offers significant benefits to aerobic athletes."
That is why researchers believe that consuming plenty of
protein along with carbohydrates offers the best fitness
benefits. Protein helps fuel activity more efficiently and
aids in recovery after a session at the gym, allowing your
body to repair muscle damage and build up muscle fibers.
During exercise, you break down muscle tissue. It is during
recovery, after your exercise session ends, that muscles are
rebuilt. At the same time, other cellular processes take
place that adapt the body to working out.
According to Ivy and Portman, timing your intake of
nutrients after exercise is crucial: "The ability of the
muscle machinery to regenerate itself decreases very rapidly
after a workout, so that the nutrients consumed more than 45
minutes after exercise will have far less impact in helping
the muscles regenerate than nutrients consumed earlier."
Stresses and Tears
Engaging in athletics can cause microscopic muscle tears.
These tears can cause a range of problems that, when you
exercise excessively, can cause pain and injury.
Inflammation is the body's response to cellular damage. The
damaged area can swell as the body sends white blood cells
and other cells to repair the injured area. Unfortunately,
the swelling can further damage the muscle cells.
Since inflammation can take 24 hours or more to cause the
collection of cells in the injured area, it can be a day or
two before the resulting muscle soreness reaches its peak
painfulness and then starts to subside.
Cortisol, a hormone produced when you exercise strenuously,
which can result in muscle fiber damage. Cortisol boosts
protein breakdown, so it can be used to fuel muscle
movement. But the more protein breaks down, the more
potential exists for muscle fiber injury.
Free radicals are caustic molecules that are created when
the mitochondria (small structures in cells) create energy;
these marauders can also cause microscopic shredding of
muscle strands. As you increase your use of energy during
exercise, you simultaneously increase the production of free
radicals. This collection of free radicals can outstrip the
body's antioxidant defenses, leading to extensive muscle
damage and dampening of the immune system.
All of these cellular events can make you sore. They are
also the reasons that athletes who overdo it day after day
are liable to come down with nagging colds and a variety of
Your muscles use different substances for fuel depending on
what you ask them to do. Lift a heavy weight and muscles
recruit two processes called the creatine phosphate system
and glycolysis to generate a large amount of quick energy.
These are known as anaerobic types of energy production.
But if you jog, swim, bike or perform any other aerobic
activity, the cells use oxygen in what is called cellular
respiration to supply energy to working muscles.
When you exercise aerobically for extended periods of time,
the energy available is generally limited by how much oxygen
your body is capable of taking in and supplying to the
muscles, where it takes part in energy production. In
athletic circles, this upper limit is known as your VO2max.
The carbohydrates your body burns for energy during aerobic
activity are taken from blood sugar and carbohydrate
reserves called glycogen. (The muscles store glycogen, as
does the liver.) During a workout session, your glycogen
supply is limited to what is stored with your muscles. But
blood glucose can be boosted by carbohydrate drinks, energy
gels or bars.
Most people who work out have enough glycogen and blood
sugar to fuel moderate aerobic activity for about two hours.
After that, the body turns mostly to fat and protein stores
to fuel exercise.
Fat Into the Fire
In contrast to the body's quickly diminishing supply of
glycogen and blood sugar, fat can last for hours and hours
of exercise. According to Portman and Ivy, a 200-pound man
with 15% body fat has, theoretically, enough fat energy to
run from Washington DC down to Miami Beach-and still has
enough energy left over to jump into the ocean.
But using fat for energy is complicated; fat is stored in
fat tissue and not readily available to working muscles.
Plus, to burn fat for energy, the body needs carbohydrate-it
cannot burn fat all by itself. What's more, the conversion
of fat into energy doesn't go as quickly as carb conversion.
Protein is also used for energy when carbs run low. But the
more you use protein for energy, the more you risk soreness
as muscle fibers break down.
Prepare to Energize
To maximize your energy during exercise and minimize
soreness, Portman and Ivy recommend some simple nutritional
� Drink 14 to 20 ounces of water or a sports drink with
electrolytes about a half hour before you work out.
Consuming fluid helps stave off dehydration longer, helps
you sweat more (which cools your body) and moderates the
rise in body temperature that takes place during exercise.
Portman and Ivy favor sports drinks to help you retain fluid
and maintain your mineral balance.
� Eat carbohydrates an hour before exercising, which boosts
glycogen and increases blood sugar and insulin. Portman and
Ivy add that, alternatively, you can also consume a
protein/carbohydrate sports drink about half an hour before
working out. The protein helps protect muscle protein from
being broken down.
� Drink small amounts of fluid frequently as you exercise to
replace water lost through sweating. While some experts
recommend only drinking enough to quench your thirst, most
researchers agree that a sports drink with electrolytes is
best to ensure proper mineral balance in your body.
� Consume carbs and protein during exercise. Portman and Ivy
note that soccer players who consume sports drinks that
contain electrolytes, carbohydrates and a bit of protein can
perform more effectively. Cyclists who go on bike rides of
three hours or more enjoy more endurance when they eat
energy bars or consume other sources of carb and protein.
Portman and Ivy advocate drinks that contain carbs and
protein in a 4:1 ratio.
Taking protein and carbs while working out can limit muscle
damage and curtail soreness. Carbs apparently drop your
cortisol levels, and thereby limit muscle injuries linked to
this hormone. While the mechanism that helps protein limit
muscle soreness is not completely understood, it is possible
that taking in protein while working out keeps the body from
shredding muscle tissue in search of fuel.
Supplements that contain antioxidants such as natural
vitamin E and vitamin C (Portman and Ivy think you should
take these during exercise) may limit free radical damage to
Muscle Reconstruction Plan
If you want to help your exercise plan make you stronger,
you should focus your after-exercise sports nutrition plan
on these steps:
� Help your muscles recover from damage during activity and
stimulate the rebuilding process
� Replace glycogen (carbohydrates) the muscles have used up
during your workout
� Reinforce your immune system
� Replace water and minerals lost in sweat
Even after you stop exercising, your muscles are still
breaking down, according to Ivy and Portman. The key to
putting the brakes on this breakdown and initiating the
rebuilding process is by consuming a combination of protein
and carbohydrate within 45 minutes after your workout is
The protein part of the equation is vital: don't merely
indulge in only carbs after exercising. A recent study found
that while carbs could help muscles rebuild, adding protein
can make a big difference in improving your fitness (J App
This combination of nutrients stimulates the pancreas so
that it releases insulin. The release of insulin is the key,
initial step that sets off a cascade of physiological events
that speeds muscle recovery. Although many people think of
insulin as an undesirable hormone-if you never exercise, too
much insulin may help drive your blood sugar down and cause
other problems-for exercisers, this hormone plays a crucial
function in benefiting from exercise.
By eating carbohydrate and protein soon after working out
and stimulating insulin, according to Ivy and Portman, you
help your body boost its synthesis of protein by:
� Increasing the amount of amino acids (protein building
blocks) that get into the muscles-this can increase by up to
� Increasing the production of protein synthesizing enzymes
by up to two-thirds
� Slowing the breakdown of muscle proteins
Drinking for Exercise
The most obvious nutrient you lose during intensive exercise
is water in your perspiration. However, that perspiration
also contains an array of minerals known as electrolytes.
So, for optimal performance and health, experts recommend
you replace both the water and its minerals.
Merely drinking water-instead of electrolyte-filled sports
drinks-during prolonged aerobic activity can be dangerous.
It leaves you vulnerable to a condition called hyponatremia,
which can occur when your blood levels of sodium and other
electrolytes drop, but your blood volume stays steady or
increases because you drink lots of water.
According to Edmund Burke, PhD, in his book Optimal Muscle
Performance and Recovery (Avery), one out of four athletes
who seek medical attention after a long race are suffering
" Typically," he says, "conscientious athletes get in
trouble because they adhere too diligently to one
recommendation: the need to drink lots of fluids. They tend
to ignore another recommendation: The need to keep
electrolytes up...for most endurance athletes the real
problem is drinking too much water." Dr. Burke warns that
you can possibly suffer hyponatremia even if you don't drink
a lot of water.
Signs of hyponatremia can be similar to those of heat
exhaustion. But, while resting and cooling down can help
alleviate heat exhaustion, that doesn't help hyponatremia. "
To protect yourself against hyponatremia, start by paying
attention to how much you sweat," Dr. Burke says. If your
sweat seems very salty, burns your eyes or leaves an
evident, white residue on your skin, you may be losing a
great deal of sodium and should be diligent about eating
salty foods. " You can also make sure you're getting enough
sodium by drinking sports drinks instead of plain water
during long (exercise) events," Dr. Burke notes.
Of course, no matter what you decide to eat or drink while
exercising, the most important factor for your well-being is
to get out to the gym, onto the track, or just on to the
sidewalk, and do something, even if you only want to go out
for a walk. No matter how old you are or what kind of shape
you're in, you'll benefit from exercise.
" It's solid evidence that across-the-board declines occur
when people stop exercising," says Charles Emery, PhD,
professor of psychology at Ohio State University (Health
Don't decline or remain supine. Let your fitness climb.