SPORT NUTRITION

When you read something on the internet do you ask yourself where the information is coming from? Is the source validated, peer reviewed or edited by the experts within the field? This is where a major disconnect can cause confusion for consumers and product developers. It is vital that marketing and research work together in explaining how proper nutrition and substantiated science backed data can support an athlete and their sport. Debunking common sports nutrition myths will help to unravel the misinformation and shed light on the importance of research backed knowledge.

There are three logical theories behind muscle cramping; one, a loss of serum electrolytes, two, excessive sweating leading to dehydration and three, an abnormality of neuromuscular control caused by muscle fatigue (1). It’s first important to recognize that the mechanism of action behind a muscle cramp is not fully understood and continues to be researched today. Nevertheless, researchers continue to test these theories to find a solution to the problem. In 2004, Schwellnus and colleagues examined marathon runners’ electrolyte levels in relation to muscle crampers vs non-crampers (control). They found that the only difference was that crampers had lower sodium and higher magnesium levels vs control. Which is intriguing because low sodium levels indicate overhydration (opposite the theory). A follow-up study was conducted with Iron Man athletes looking at the same variables. The crampers at the end of the competition showed lower levels of sodium and higher levels of potassium and magnesium versus the controlled non-crampers (2). Since electrolyte and dehydration measures in athletes continue to show inconclusive results in studies, the third theory is to be explored. It is hypothesized that “fatigue causes cramps by interfering with the normal balance of spinal reflex control, it switches on the alpha motor neuron and the muscle contracts involuntarily” (3). The electrical activity of the muscles in cramping runners was measured after a marathon and found that alpha motor neuron activity was higher than non-crampers (1). Even more fascinating is that after 20 seconds of passive stretching the EMG activity goes down in the cramping athlete (3). Thus, indicating that perhaps electrolyte depletion and dehydration may not be the direct cause and the theory of muscle fatigue might have better explanation for the cramping phenomenon (surprise; further research is needed).

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Despite the enormous amount of supporting research, the public continues to believe the amount of protein the human body can absorb in one meal is 30 grams. It is speculated that any exceeding amount of protein, after being utilized for muscle protein synthesis (MPS) is either excreted or stored as fat (4,5,6). A plethora of research studies continue to debunk this myth, like Kim et al (6). Muscle protein turnover rate and MPS was measured following the consumption of different protein amounts. Those who consumed 1.5g/kg of protein (~35-40 grams of protein per meal) presented greater levels of whole-body protein balance and MPS compared to the 0.8g/kg group (~20grams of protein per meal). Moore et al.(7) measured MPS and albumin protein synthesis rates in subjects consuming 0, 5, 10, 20, and 40 grams of protein in a sitting. At 40 grams, concentrations of essential amino acids and branched-chain amino acids were greatest. Those studies noted the utility of protein over the normal limit, however, what about weight gain and body composition measures. Bray et al. (8) evaluated the effects of higher protein intakes on fat/lean body mass. This overfeeding study had subjects consume a low (5% protein energy intake, ~8g of protein per meal), normal (15%, ~25g of protein per meal), or high (25%, ~40g of protein per meal) for 10-12 weeks. While all groups gained body mass (no surprise, it is an overfeeding study) the higher protein group promoted to the greatest increase in lean body mass. Antonio et al.(9) studied high protein intakes in resistance trained men for 1 year. Interestingly, while the subjects’ diets increased ~400 calories, they did not experience an increase in fat mass. This is important information for product developers looking to create protein supplements containing more than 30 grams of protein in a single serving (the research is on your side).

Emerging trends and fad diets invade social media outlets, and these trends are starting to influence product developers in making new goods to match the consumer request. However, some popular trends do not give merit or acknowledge what sound science says. For example, the recommendation for athletes to switch to sugar-free drinks and avoid foods like fruit, may be more harmful to the athlete than good. Basic human physiology tells us that glucose (simple sugar) is the preferred source of energy for muscle contraction during exercise (10). Numerous studies have looked at the relationship between athlete performance/recovery and carbohydrate (sugar) consumption. Little et al. study showed a benefit to consuming carbohydrate-rich meals prior to exercise in that the distance covered on a repeated-sprint test was significantly greater in this group vs control (fasted athletes) (11). Fructose (sugar from fruit) is another form of energy for muscle contraction. Rowe et al. (12) performed a double-blind placebo-controlled trial with runners testing their performance in relation to a glucose-fructose rich hydrogel. Time-trial performance was significantly faster after consumption of the hydrogel vs placebo. The stored form of glucose is glycogen and it has been suggested that exercise is severely compromised when skeletal muscle glycogen stores are depleted (consuming little to no glucose before or after exercise will contribute to a decrease in glycogen stores) (13). This is why endurance athletes are recommended to maintain a carbohydrate-rich diet, which includes sugar in their meals and drinks. Sugar is not the enemy and for athletes it’s essentially the opposite. Of course, everything in moderation (too much of a good thing, can be bad).

There are nine essential amino acids (AA) that the human body requires to maintain optimal health and functionality. AAs help facilitate gene expression, syntheses of hormones, and cell signaling properties (14). Amino acids are the building blocks of protein, and certain AAs regulate key metabolic pathways. A popular supplement on the market is branched-chain amino acids or BCAAs; leucine, isoleucine and valine. BCAA supplement companies make claims that they help increase the anabolic process and enhance muscle recovery times. While there is some research to support the use of BCAAs, the vast majority recognize that BCAA supplementation has little to no effect on performance/recovery (15). Watson et al. reported no beneficial effects from BCAAs being consumed before and during prolonged cycling to exhaustion (16) and Cheuvront found similar effects with time-trial performance (17). The claim that BCAAs alone can produce an anabolic response (building muscle) has been thoroughly reviewed in the literature and has revealed no studies in human subjects where MPS was positively affected (18). In fact, Wolfe performed an extensive search of the literature that concluded with the consumption of dietary BCAAs stimulating MPS or producing an anabolic response in humans was not warranted (18). Although BCAAs may (and I stress “may”) help to improve muscle growth and recovery it is much more beneficial to see and feel the full effect of these areas with foods or supplementation containing all essential amino acids found in whole protein sources such as whey, casein, and pea protein powders.

KATIE M. EMERSON
Nutrition21 LLC. | USA