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

1. Sports Med. 2010 Nov 1;40(11):941?59.
2. J Strength Cond Res.2014 May;28(5):1443?53.
3. Br J Nutr. 2012 Apr;107(7):1048?55.
4. J Nutr Sci Vitaminol(Tokyo). 2005 Feb;51(1):1?7.
5. Nutr Metab(Lond). 2006 Jul 17;3:26.