Protein Supplementation and Athlete Performance

Leucine has been widely studied in its role in stimulating muscle protein synthesis (MPS), and is considered an important component in sports nutrition products.

January 16, 2017Global Food Forums, Inc.The following is an excerpt from the “2016 Protein Trends & Technology Report: Formulating with Proteins,” sponsored by Arla Foods Ingredients, Amco Proteins, Givaudan, Orochem Technologies, RiceBran Technologies and Synergy. 

Hoffman-chart

“Leucine saturation” is the theoretical, minimal single oral dose of leucine required to maximally stimulate muscle protein synthesis (MPS). From the sources of protein listed here, some 20-30g are needed to maximize MPS for untrained athletes. Present understanding appears to support the use of milk or animal-based proteins to maximize muscle protein synthesis and changes in lean body mass. [For larger PDF of chart, click on image.]

Much of our knowledge of sports nutrition is based on empirical evidence from athletes. One of the biggest controversies is how much protein an athlete needs. Active individuals need more protein than those who are sedentary, but is there a ceiling?

At the 2016 Protein Trends & Technologies Seminar, Jay Hoffman, Ph.D., of the Institute of Exercise Physiology and Wellness and the University of Central Florida, discussed this issue in his presentation titled “Protein Supplementation and Athletic Performance.”

Protein sources vary widely in their amino acid profile. There are four common methods to evaluate protein quality. Biological Value (BV), Net Protein Utilization (NPU), Protein Efficiency Ratio (PER) and Protein Digestibility Corrected Amino Acids Score (PDCAAS.) Brown rice, soy protein and wheat are lower quality proteins, which create a challenge for vegetarians. Another important aspect of protein quality is absorption rate.

Whey protein isolate has the highest absorption rate, which means it is absorbed in the blood more quickly than other proteins. This is important for recovery from exercise and maximizing adaption to exercise, explained Hoffman.

The RDA for protein represents the amount necessary to maintain nitrogen balance and muscle mass under sedentary conditions. “If protein degradation is greater than protein accretion, then an individual is in negative nitrogen balance, or a catabolic state. Resting is very catabolic. The opposite is true for individuals who exercise and consume adequate protein to stimulate muscle protein synthesis. These individuals are in positive nitrogen balance, or an anabolic state. The combination of feeding protein and exercising is a potent stimulus for protein synthesis,” Hoffman said.

Protein needs for sedentary individuals are estimated to be 0.8 grams per kilogram of body weight per day (g/kg/day). For runners, protein needs jump to 1.2-1.4g/kg/day. For strength and power athletes, needs increase to 1.8-2.0g/kg/day or higher.

Hoffman’s group conducted research using competitive athletes to learn how greater protein intake affected performance. The athletes were divided into three protein intake groups and performed a 12-week resistance training program. The below recommended intake (BL) group consumed 1.0-1.4g/kg/day; the recommended intake (RL) group consumed 1.6-1.8g/kg/day; and the above recommended intake (AL) group consumed greater than 2.0g/kg/day. Individuals in the BL group had a decrease in lean body mass. The AL group had statistically significant increases in bench-press strength. Another study showed significant decreases in fat mass in a high-protein group vs. a normal protein group.

Generally, dietitians and sports medicine organizations take a conservative approach to supplementation. The consensus among these organizations is that protein needs can usually be met through food intake. However, the most convenient and efficient method for providing immediate protein after exercise may be with a protein supplement. Recent studies have shown that providing protein supplementation can decrease muscle damage, attenuate force decrements and enhance recovery.

A recent meta-analysis from 22 randomized, controlled studies that include 680 participants compared results of protein intake on fat-free mass. Results revealed protein supplementation, in combination with resistance training, can significantly augment gains in lean body mass.

A study by Volek compared soy and whey over time. The protein amounts were the same, but the leucine content of the whey group was higher. After nine months, the whey group had a 45% greater increase in lean body mass than the soy group. A number of studies have shown that there is a leucine  threshold, a theoretical minimum dose of leucine required to stimulate an increase in muscle protein synthesis, of 1.5-2.0g/day. Whey protein has the highest content of leucine and is the most effective leucine trigger.

“Protein Supplementation and Athletic Performance,” Jay R. Hoffman, Ph.D., Director, Institute of Exercise Physiology and Wellness, Sport and Exercise Science and Burnett School of Biomedical Science, University of Central Florida

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