Google the words ‘protein supplements for athletes’ and a number of links will appear in your browser. While apparently just a click away from learning the ‘truth’ about these dietary additions, it is advisable to consider the nature of whichever website you fall upon before hollering hallelujah. Company websites marketing protein supplements claim to give athletes the ability to ‘beat their best competition’ and to ‘get bigger and/or stronger’. Promasil, ‘the athlete’s protein’, for example, features seven of the world’s most powerful proteins. Imagine the industrial strength containers needed to keep these key ingredients from escaping. No more five dozen eggs a day to grow biceps the size of barges (the strategy adopted by Disney’s Gaston), a more palatable and practical solution is delivered in the form of a delicious flavoured powder. Since proteins are a major component of muscle, it surely makes sense that consuming more would result in extra bulk. But protein supplementation is not only about bodybuilding. For those more concerned about beating personal bests and leaving the competition trailing behind, protein supplements are also argued to directly enhance endurance performance and to optimise recovery of muscle function following exercise.
So how does it work? Naming a chocolate bar after a long-distance running event (and later rebranding using a word that sounds like underwear in British vocabulary – ‘Snickers’), no doubt taught the importance of carbohydrate as an energy source. Through reduced breakdown of carbohydrate during prolonged exercise, protein supplements are thought to enhance performance and to more quickly replete muscle glycogen (a specific type of carbohydrate) during recovery. By stimulating muscle protein synthesis, protein supplementation is also theorised to reduce muscle damage and speed up the recovery of muscle function. If you recently ran down a hill or lifted some weights, ideally not at the same time, you may later have felt soreness in your muscles, caused by damage to proteins that are required for muscle contraction. In such circumstances, rates of muscle synthesis and degradation are increased, and without sufficient protein intake, rates of degradation exceed synthesis and a negative net protein balance results. Consuming protein supplements during recovery from exercise should, however, promote the production of skeletal muscle (muscle that is attached to bones and contracts on demand).
Despite the logic behind these claims, a systematic assessment of the evidence to support or refute the relationship between the use of protein supplements and exercise performance, muscle damage and soreness, and recovery of muscle function has until recently been lacking. Earlier this year, Pasaikos, Lierberman and McLellan addressed this dearth by publishing two review articles in the journal Sports Medicine. Examining publications reporting findings from ‘healthy human adults’ (no chimpanzees thankfully) between 18 and 50 years of age, they found no apparent relationship between recovery of muscle function, muscle soreness and muscle damage when protein supplements were consumed prior to, during or after a bout of endurance or resistance exercise. If supplemental protein was consumed after daily training sessions, however, beneficial effects such as reduced muscle soreness and damage became more evident. They also found that when carbohydrates were at optimal levels during or after exercise, protein supplements provided no performance enhancing effects. In particular, sparing of muscle glycogen stores was not supported as a mechanism leading to enhanced endurance performance.
Pasaikos et al. warned, however, that small numbers of participating adults and lack of dietary control limited the effectiveness of several of the investigations they examined. Since studies did not measure the effects of protein supplementation on direct indices of muscle damage or muscle glycogen, for example, the interpretation of the data was often limited. What does seem clear, however, is that if athletes maintain a healthy diet, by consuming enough protein and carbohydrate through traditional means (for example regular food), protein supplements are unlikely to generate record breaking results. Only when the healthy human adults involved in the studies examined by Pasaikos et al. were lacking in nitrogen (found in amino acids that make up proteins) and/or energy balance were performance enhancing effects of protein supplements found to be greatest. Endurance is of course built by training and not protein alone. Whilst Pasaikos et al. demonstrated the need for further high quality research on the potential benefits of protein supplements, a healthy diet, sufficient rest and undeterred dedication seem to be best recipe for success.