Nutrition Notes

Fuel Exercise Properly

Exercise and regular physical activity are the primary means of enhancing physical fitness, which plays a critical role in overall health and wellness. However, exercise alone is not sufficient to yield the positive health outcomes many seek. To get optimal results, exercise should be paired with appropriate nutritional support for athletic performance and recovery.

Protein is the most well-studied macronutrient in the context of exercise performance. While it can have modest benefits in endurance exercise, it really shines in resistance training and for improving body composition. The International Society of Sports Nutrition (ISSN) provides critical reviews of the current research on protein and exercise. According to a recent ISSN publication, consuming supplemental protein during and after intense endurance exercise can suppress markers of muscle damage and improve measurements of muscle soreness 12 to 24 hours post-exercise. For resistance training, daily protein intakes that exceed 2.0 grams/kg of body weight per day can increase muscle strength up to 42 percent. The positive effects of protein supplementation on muscle strength gradually increased as the duration, frequency and volume of resistance training increased. As muscle strength increases, muscle hypertrophy tends to follow, leading to a shift in body fat percentage that favors lean muscle mass. Therefore, protein supplementation coupled with resistance exercise may help improve body composition.

Not all protein functions equally in supporting physical fitness. Whey protein has been found to be an excellent form of supplemental protein for exercise. When processed minimally and sourced from the milk of grass-fed cattle, whey protein contains an abundance of healthful nutrients including alpha-lactoglobulin, beta-lactalbumin, immunoglobulins, bovine serum albumin, lactoferrin, lactoperoxidase, phospholipoprotein, bioactive factors, and enzymes. More importantly, whey protein contains high amounts of branched-chain amino acids (BCAAs) and the high leucine content helps stimulate muscle protein synthesis and elevate mammalian target of rapamycin (mTOR) signaling activation.

Even endurance athletes can benefit from whey protein. In a randomized, double-blind study comparing the effects of consuming whey protein versus a maltodextrin placebo in National Taiwan Sport University male track team elite athletes for 5 weeks, it was found that 33.5 grams of whey protein administered within 30 minutes after training resulted in lower aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), and creatine kinase (CK), blood urea nitrogen (BUN), triglyceride, low-density lipoprotein (LDL) and total cholesterol levels compared to placebo. The weight, BMI, and muscle mass of the whey group were significantly higher than those of the placebo group. Collectively, this shows that whey protein supplementation can function to reduce exercise-induced oxidative damage in the liver and promote muscle recovery.

Skeletal muscle is highly sensitive to nutritional intake. Resistance exercise stimulates rates of muscle protein breakdown, but there is a greater stimulation of the rates of muscle protein synthesis. Exercise triggers phenotypic changes in skeletal muscle to increase mRNA expression and translation of protein. These phenotypic changes increase and adapt with sustained exercise. However, rates of muscle protein synthesis exceeded those of muscle breakdown only when adequate protein was consumed (20 to 40 grams over a 12 hour recovery period), resulting in positive muscle protein balance and net protein accretion.

The efficacy of whey protein is based in part on its content of BCAAs, but direct intake of these select amino acids is an alternative for those who are dairy sensitive. BCAAs include leucine, isoleucine and valine. They are unique among essential amino acids in that they are extrahepatically metabolized in skeletal muscle. Their oxidation is promoted by exercise, explaining their usefulness in decreasing exercise-induced muscle damage and promoting muscle protein synthesis. In a meta-analysis of randomized controlled clinical trials examining the effect of BCAAs on recovery following exercise-induced muscle damage, results confirmed positive effects of these select amino acids in reducing muscle soreness and promoting muscle recovery.

Research informs us that protein is a crucial nutrient for meeting the goals of exercise and enhancing physical fitness. Whey protein offers a superior form of protein for protecting muscle breakdown and supporting muscle protein synthesis, and branched-chain amino acids are key nutritional elements for these purposes.