ISSUE
#14
INSIDE
THIS ISSUE...
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"Post-Workout Supplementation"
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"The High-Protein Diet"
-
"The High-Carbohydrate Diet"
1
- POST-WORKOUT SUPPLEMENTATION: YOUR MOST IMPORTANT MEAL!
In
this age of complex supplementation, the basics of sport nutrition
have been forgotten. Simply put, in order to gain mass one
must stay in an anabolic state. The off-season is often a
time focusing on strength gains and hypertrophy. Hypertrophy
is an essential step towards developing greater strength because
in the most basic equation, strength correlates with the cross-sectional
area of the muscle. The easiest way to attain a consistent
anabolic response is through a properly scheduled intake of
nutritionally balanced meals.
A
post-workout drink is optimal for providing a balance of protein
and carbohydrates plus it provides the added bonus of an improved
hydration state. The continuous presence of calories will
fuel muscle growth and recovery by supporting protein and
glycogen synthesis. Periods of more than 3-4 hours without
food can result in a post-absorptive catabolic state.
Muscles
are catabolized ("broken down") for energy, essentially
robbing you and your muscles of all the hard work and growth
previously accomplished. Immediate post-exercise energy consumption
prevents a delay in the delivery of energy substrates to the
depleted muscle cell and is therefore an important method
to remain anabolic.
Post-exercise
feeding can reduce protein degradation and increase protein
synthesis. Post-exercise caloric intake is also necessary
to restore liver and muscle glycogen (energy stores). The
benefits of a post-workout drink occur through the hormonal
response to insulin and an increase in amino acid uptake by
muscles is also due to an increase in insulin.
Carbohydrates
should not be left out of the post-exercise drink because
these are necessary to provide the insulin "spike"
and are an essential source of energy for the recovery process.
Ingesting a mixed carbohydrate-protein drink after training
is much more anabolic than consuming only a protein shake.
This is also an optimal period for creatine supplementation.
Protein
provides the building blocks for muscle growth. Protein synthesis
increases 50% 4 hours and 109% 24 hours post-training (MacDougall
et al., 1995). The nutrient intake within this time period
thus has important implications on the adaptations to training.
The protein recommendation for experienced strength athletes
is ~1.7 g/kg while novice trainers may need more.
Requirements
may transiently increase if intensity or volume of activity
is increased (up to ~ 2g/kg) and especially for athletes involved
in both strength and speed activities. Endurance exercise
also creates an increase in protein requirements of up to
1.6 g/kg/day because of the increased catabolism of protein
during exercise. To assist in meeting these requirements,
supplements should contain at least 20 grams of protein per
serving.
The
carbohydrate component should consist of simple, high-glycemic
carbohydrates because of their fast absorption into the bloodstream
and quick delivery to muscle cells (Burke et al., 1993). The
increased cellular sensitivity to insulin post-exercise provides
for the rapid delivery and intra-cellular transport of glucose
and creatine.
Carbohydrate
has also been shown to have anabolic properties by helping
to prevent protein breakdown through the insulin-stimulated
response. The increased insulin levels post-exercise will
not result in increased fat storage because skeletal muscle
is the primary consumer of nutrients at this time.
Carbohydrates
cause glycogen re-synthesis and replace the fuel source previously
depleted by your resistance training (Ivy et al., 1988). The
dose of post-exercise carbohydrate should be 0.7-1g/kg (Burke
et al., 1996). Glycogen synthesis can be impaired by eccentric
muscle damage (Costell et al., 1990) but fortunately most
resistance training programs incorporate several rest days
before the same muscle group is trained again, therefore glycogen
depletion is not a big issue in strength training. The highest
rates of glycogen re-synthesis occur following energy intake
that is within 2 hours of training (Ivy et al., 1988).
Perhaps
even more important is the fact that 1g of carbohydrate per
kg body weight has been shown to prevent post-exercise protein
breakdown (Roy et al., 1997). Therefore optimal energy intake
occurs A.S.A.P. (within 30-minutes of training may be best)
in order to raise insulin levels (an anti-catabolic hormone).
This is extremely important if a second training session is
scheduled within 24 hours, such as for individuals training
related muscle groups and athletes involved in tournament
play.
Individuals
that often complain of the inability to gain weight simply
do not consume enough calories. A large portion of the sedentary
American population has mastered weight gain through inactivity
and constant snacking. Although fat weight is not desired,
this scenario can be applied to hard-gainers. Work hard, rest
harder, and stay anabolic. Post-exercise supplementation is
essential for enhancing the anabolic environment and limiting
the potential for exercise-induced catabolism. These extra
calories are welcomed by the hard-gainer for use in growth
and repair.
A
post-exercise drink also prevents dehydration as any weight
loss following training is due to water loss. A post-exercise
drink or meal-replacement can contribute to the recommended
intake of 10 cups of non-caffeinated fluids per day. Because
there is no difference in energy replenishment between a liquid
and solid food source (Burke, 1996), a liquid meal-replacement
appears to be most beneficial post-exercise.
Other
factors demonstrate the superiority of meal-replacements over
whole food in the post-exercise condition. Often athletes
are fatigued and do not have the energy to prepare food or
do not have the appetite for whole-food. Finally, the access
to food may be limited, especially when other priorities demand
time and energy and limit the time the athlete has to return
to work or home while still consuming adequate calories.
References
Burke,
L.M. Nutrition for post-exercise recovery. Aus. J. Sci. &
Med. 29: 3-10, 1996.
Burke,
L.M., G.R. Collier, and M. Hargreaves. Muscle glycogen storage
after prolonged
exercise:
effect of the glycemic index on carbohydrate feedings. J.
Appl. Physiol. 75: 1019-1023, 1993.
Costell,
D.L., D.D. Pascoe, W.J. Fink, R.A. Robergs, S.I. Barr, and
D. Pearson. Impaired
muscle
glycogen re-synthesis after eccentric exercise. J. Appl. Physiol.
69: 46-50, 1990.
Ivy,
J.L., M.C. Lee, J.T. Brozinick, Jr., and M.J. Reed. Muscle
glycogen storage after
different
amounts of carbohydrate ingestion. J. Appl. Physiol. 65: 2018-2023,
1988.
MacDougall,
J.D. et al. The time course for elevated muscle protein synthesis
following
heavy
resistance exercise. Can. J. Appl. Physiol. 20: 480-486, 1995.
Roy,
B.D., M.A. Tarnopolsky, J.D. MacDougall, J. Fowles, and K.E.
Yarasheski. Effect
of
glucose supplement timing on protein metabolism after resistance
training. J.
Appl.
Physiol. 82:1882-1888, 1997.
2
- THE HIGH-PROTEIN DIET
Recently,
the high-protein diet advocated by Dr. Robert Atkins has become
extremely popular. Forty percent of people polled by CNN Interactive
have tried a high-protein, low-carbohydrate diet. Unfortunately,
40% of these individuals also said they gained some or all
of the weight back, in comparison to only 15% of individuals
polled that had lost weight by following a balanced diet.
The
high-protein diet contributes to rapid weight-loss by depleting
the muscles of glycogen. Glycogen is the storage form of carbohydrate
in the body, and is stored in a 1-to-3 ratio with water. Therefore,
when glycogen is depleted, an extreme amount of water is lost
simultaneously and the individual is tricked into believing
there has been a large amount of fat lost. Thus, it appears
the high-protein diet is a quick weight-loss route but may
be only moderately successful at long-term weight reduction.
3
- THE HIGH-CARBOHYDRATE DIET
On
the other hand, a separate study found that eating refined
carbohydrates (pasta, white bread, and other rapidly digested
sugary foods) lead to overeating by triggering hormones that
trick the body into believing that it is still hungry. As
well, many individuals consume a large amount of energy (calories)
through drinking. Individuals that drank 450 calories of sugar
(soda) per day gained more weight than when they ate 450 calories
of sugar (jellybeans) per day. The jellybean condition caused
the subjects to eat less at other meals while the soda condition
did not result in a reduction of food intake.
The
lesson here is that unless energy and rehydration is extremely
necessary, caloric intake through fluids should be limited.
Exceptions include drinks containing essential vitamins and
minerals, such as a daily juice or milk on cereal. However,
make sure you drink plenty of water to keep hydrated throughout
the day and during training.