Athletic training is based on principles such as
physical overload, meaning that the body is taxed to
near its limits and then allowed to recover with the
expectation that recovery will be quicker in the future for the
same level of exertion and that the body will over-compensate
at recovery and thus allow even more exertion upon the next
challenge. This demand-and-response model clearly taxes bodily
reserves. Some supplements, for example, protein, are aimed
mostly at recovery and super-compensation. Others, such as
creatine, also provide super-physiologic levels of substrates,
in this case a substrate for the replenishment of adenosine
triphosphate (ATP), allowing the muscles to go beyond their
normal physiologic capacity. There is not much question but
that both of these objectives can be achieved to some degree,
meaning that supplements can be valuable for supporting and
increasing physical performance and, used properly, can reduce
the risks of injury.
There is no one size-fits-all in supplementation, however.
For instance, although it clearly is the case that supplemental
amounts of certain antioxidants can help to maintain health
and improve recovery, it also is true that the type, timing and
amounts of antioxidants can exert other effects. Indeed, the
physiological adaptations to exercise may be blunted when
local oxidant production in the muscles is suppressed by
supplemented antioxidants. Some aspects of muscle supercompensation
in response to exercise challenges depend
directly on the local formation of oxidants and free radicals.
Protein
The king of muscle building proteins probably is whey protein
because of its high content of the branched-chain amino acid
L-Leucine, which can induce muscle synthesis, but only if there
are sufficient other nutrients available to sustain the creation
of new muscle tissue. Whey protein is a favorite of most
authorities and has the additional virtues, if it remains largely
"natural" in its structure, of supporting the body's production
of glutathione.
Because protein sources are digested and absorbed at
different rates, one of the more interesting findings of recent
years is that a mixture of proteins with different rates of digestion
and assimilation is superior to single protein sources. In this
case, adding casein and soy protein to whey protein in human
trials, especially in the recovery phase, appears to improve
results. Clinical finds thus suggest that multi-protein blends,
properly constructed, may trump any single source of protein
for supporting athletic performance. Pea protein recently has
attracted a great deal of attention.
It is generally agreed that nutrients taken immediately after
exercise are readily taken up into the muscles. Some studies have
reported improved physical performance with the ingestion of
carbohydrate-protein mixtures, both during exercise and during
recovery prior to a subsequent exercise test.1 Consuming simple carbohydrates and
carbohydrate-only supplements, even prior to workouts, has
fallen out of favor.
Also, it should be borne in mind that the initial meal of
the day may play a large role in setting the flexibility of the
metabolism for the rest of the day. A higher ratio of protein
and fat at breakfast tends to make the metabolism of fat for
energy easier throughout the day whereas excessive refined
carbohydrates will have the opposite effect.
Pre- and post-workout supplements generally involve a
considerable volume of ingredients. The tub-versus-bar option
is really only about convenience. Tubs will deliver protein that
is much less expensive gram-for-gram and not necessarily have
a ton of fillers. Protein bars almost of necessity will include
sweeteners and binders because these are required to make
the bars palatable and to hold them together. On a gram basis,
as long as the same quality protein source(s) is being used,
there should be little difference in efficacy between these two
deliveries.
Creatine
Workout supplements often involve tradeoffs. For instance,
why would an athlete have to take creatine if they are already
supplementing with a protein? Are here any additional health
benefits to a person that takes both?
Creatine and protein do different things. Creatine primarily
repletes a precursor to ATP to greater levels than can be
accomplished under normal physiologic conditions. Creatine
itself is not a "building block" for muscle tissue. Refined protein
supplements seldom are sources of this compound. Although
it is possible by taking extremely large amounts of arginine to
provide the body with a means of increasing its own synthesis
of creatine, this is not efficient. Some sources of protein, such
as red meat, themselves can supply small amounts of creatine.
However, again, this is not an efficient means of increasing
muscle creatine levels compared to consuming creatine
monohydrate directly. Athletes who benefit from creatine
supplementation, therefore, should consume creatine for its
particular benefits and protein for muscle repair/recovery/
augmentation.
Creatine has well established ergogenic benefits for
strength and greater performance in a number of areas of
athletics, primarily events that are short term and explosive in
nature as opposed to being oriented towards endurance. For
those individuals who train heavily, there are obvious benefits.
Body builders who desire the greater bulk similarly may find
the muscle edema to be acceptable for aesthetic reasons.
Nevertheless, it is true that creatine supplementation that is
not coupled to training primarily will lead to a certain amount of muscle edema without other benefits. Likewise, most endurance athletes will not find the weight issue to be counterbalanced by
sufficiently enhanced performance to make supplementation
beneficial for their sport.
Endurance
Nutritional regimens in sports often are planned with specific
goals in mind because different goals strongly influence the
roles of carbohydrate, fat and protein in supplements for
athletes. For instance, building muscle mass is a goal with
requirements different to those for getting lean or maintaining
balance in terms of muscle and bodyweight. Caffeine is a
common ingredient used by most athletes despite the fact that
caffeine does not seem to be an ergogenic aid except for those
who do not routinely consume it via coffee, soft drinks, tea, etc.
Pre-workout supplements, which usually are consumed
30 ?60 minutes prior to working out, are designed to increase
energy during workouts and provide accessible calories to
spare glycogen and thus extend time to failure. Common
nutrients include nitric oxide precursors, such as forms of
L-arginine and L-citrulline as well as vasodilating herbs. Some
formulators suggest the addition of ribose, but others prefer
to use ribose either after workouts and/or during workouts.
Rhodiola, ginseng and astaxanthin are other supplements
used to increase endurance, the latter for its role in improving
the ability to metabolize fats for energy. Pre-workout energy
drinks based on only carbohydrates or carbohydrates plus
caffeine have not fared well in tests.2
Post-workout supplements are intended to take advantage
of a 30?60 minute window of opportunity following workouts
during which cells are especially open to absorbing and utilizing
nutrients for recovery, including replacing glycogen and restoring
lean muscle that often is lost in endurance training. The focus of
these products typically is on carbohydrates to replete glycogen
and, to a lesser extent, protein quality and quantity. A favored
approach is based on replacing glycogen as the key to athletic
recovery and therefore pushes high glycemic carbohydrates as
primary via ingredients such as waxy maize, maltodextrin and
starches from potato and rice. Ribose is another ingredient often
seen in these formulas. It should be kept in mind that the wisdom
of chronic ingestion of high glycemic index carbohydrates has
been challenged by a number of health authorities. Micronized
protein increasingly is added to increase insulin response and
muscle uptake of nutrients. Taking a good quality hydroxycitric
acid (HCA) supplement during recovery has been shown to
significantly improve the replenishment of muscle glycogen.3
A proper HCA supplement can be very hard to find?the most thorough research in the
area of sports performance had to use a synthesized trisodium
hydroxycitrate to achieve results.4 Similarly, a relatively pure potassium HCA
salt is more efficacious than a potassium-calcium salt.5
During (Intra) workout supplements are now common.
Over the past decade, it has become more popular to consume
nutrients during workouts and not just prior to workouts and
after exercise. However, there does not appear to be a consensus
as to whether intra-workout supplements should focus on
carbohydrates alone or on combinations with small amounts of
easily absorbed protein. Many products contain both. Common
ingredients aside from the carbohydrates already named are
branched-chain amino acids, glutamine, creatine and betaalanine.
In recent trials, drinks that supplied less carbohydrate
and replaced these calories with a moderate amount of protein
led to significantly improved endurance performance in trained
long-distance cyclists. It turned out to be the case that fewer
calories with a lower level of carbohydrate and more protein
worked better in extending time to exhaustion, reducing
muscle damage and improving post-exercise adaptation to the
challenge of exercise overload.
Caffeine is another contentious topic. Caffeine has
numerous natural sources, including coffee beans, tea,
cocoa beans (chocolate source), kola nut, guarana and yerba
mate. However, caffeine does not tend to improve athletic
performance unless used in quite large amounts and only during
competitions. Alternatives include specialized ginseng extracts,
L-tyrosine (may increase blood pressure in some individuals),
schizandra berry extract and ashwagandha extract. Astaxanthin
has been shown to increase endurance performance.
Endurance athletes in particular should pay attention to
the issue of electrolytes. Although there are some unfortunate
examples of excessive hydration in athletes, generally speaking,
athletes can easily lose enough fluid to lead to reduced
performance. Electrolytes, if nothing else, are necessary to
bring ingested fluids to the isotonic molarity that will allow
them to be readily absorbed by the body. Betaine, which is used
in the manufacture of food and beverages, is well studied as
a hydration agent. Betaine is an organic osmolyte that helps
to stabilize metabolic functions in the face of dehydration and
overheating. The usual electrolytes lost in sweat, of course, are
potassium and sodium. Increasingly popular in Europe in this
area is a combination of salts including potassium, sodium,
magnesium and calcium in the form of glycerophosphates.
Whether electrolytes are necessary beyond their role in
promoting proper hydration remains highly debated.
Conclusion
Supplements can play important roles is exercise. The pure
carbohydrate products in favor a few years ago, however, no
longer are the best supported by research. Protein, protein/
carbohydrate mixtures and combinations of proteins from
different sources now are favored. Similarly, athletes who are
looking for performance enhancement rather than merely a
psychological lift increasingly shy away from simple caffeine
and other stimulants. Supplements should be picked for the
sport (body building or endurance, for example) and keyed to
the expected benefits.
References
- Sports Med. 2010 Nov 1;40(11):941?59.
- J Strength Cond Res.2014 May;28(5):1443?53.
- Br J Nutr. 2012 Apr;107(7):1048?55.
- J Nutr Sci Vitaminol(Tokyo). 2005 Feb;51(1):1?7.
- Nutr Metab(Lond). 2006 Jul 17;3:26.
