Soy… The Right Protein for Fitness and Performance Nutrition
Source: The Soy Daily Club

Ari Babaknia, MD, Adjunct Associate Professor, Human Nutrition, Oklahoma State University and Belinda Jenks, PhD, FACN

Soy Protein and Athletic Performance; Benefits of Soy Protein for Body Building, Endurance Sports and for Energy and Toning

Protein plays a major role in building and maintaining muscle mass. Whether you exercise as a weekend warrior or want to increase your lean muscle mass and performance as a professional or serious athlete strenuous training and maintaining a high energy level is important. The first step is to eat a healthful diet and choose proteins and other nutrients that support performance, strength and endurance. Studies have shown that soy protein, a high quality protein supports formation of lean body mass, enhances muscle recovery and improves reduces the oxidative stress or muscle inflammation in individuals exercising and undergoing intensive training programs. Professional athletes, recreational athletes, Olympic athletes and people with active lifestyles have used soy protein as part of their daily training diet with improved measurable results.

Soy protein has a number of benefits. Several of those pertaining to performance include:

Soy protein is a high quality protein and contains all of the essential or indispensable amino acids in quantities required to support protein synthesis Soy protein is plant-based and is equal in protein quality to milk, whey, and meat and egg protein. Soy protein contains all of the indispensable amino acids in the correct proportions and amounts required by child and adult based on the guidelines given by the WHO/FAO/UNU. It is the only protein of plant origin that provides all these essential amino acids for human needs. (A complete protein is a food protein containing all of the essential amino acids in the right proportions and amounts to meet human needs for growth, maintenance and repair of living tissues).

Soy protein and the component parts, the amino acids, serve as building blocks for synthesis of protein into skeletal muscles. Muscles also need protein to repair, rebuild and grow. Studies in humans have demonstrated that soy protein used as the sole source of protein in the daily diet will support normal muscle formation and maintain nitrogen balance. Additionally, soy protein has a unique amino acid profile.

Soy protein contains higher levels of the conditionally essential amino acids, arginine and glutamine. These amino acids may be needed during physiological stress such as training. Arginine promotes anabolic (building) activity of muscle that results in muscle formation.

Glutamine buffers lactic acid-build up to reduce fatigue in the body during and after exercise. During exercise glutamine concentrations are reduced in the blood and muscle. Some exercise physiologists believe that higher levels of glutamine taken in the diet help to enhance muscle formation.

Both arginine and glutamine are recognized to contribute to the health of the immune system.

The soy protein branched chain amino acids (BCAA) leucine, isoleucine and valine are used as an energy source during exercise. In the first 20 minutes of moderate to intense exercise, muscle glycogen is used as the primary energy source and provides glucose for muscle fueling. After this initial 20 minutes phase of exercise, fatty acids and the BCAA are used as major energy sources. The BCAA has an increased uptake by muscle yet not by the liver and have an increased rate of oxidation during exercise. Researchers continue to evaluate the efficacy of the branched chain amino acids for reduction of central nervous system fatigue as well as their use for the enhancement of immune system functions.

Soy protein containing natural occurring isoflavones is an excellent source of antioxidants for enhancing human health.

This antioxidant capability can help in reducing muscle soreness and fatigue following exercise, therefore speeding up muscle recovery and ultimately enhancing muscle performance.

Soy protein promotes cardiovascular health by lowering total and LDL (bad) cholesterol and improving vascular wall flexibility. Both of these could add to the already achieved cardiovascular and long-term general health benefits associated with exercise training.

Antioxidants and Exercise

Although exercise is generally considered health promoting; however acute exercise can serve as a mild form of oxidant stress which may contribute to fatigue and risk of muscle injury. Furthermore, such oxidant stress may have long term, negative effects on overall human health. Oxidant stress has been implicated in many diseases including coronary heart disease and cancer. This could be problematic for the so-called "weekend warrior," who engages in strenuous, but irregular exercise. Such an individual may not make adequate adaptations to protect him or herself for intermittent oxidant stress. Another vulnerable group may be an elite endurance athlete, who might overwhelm protective adaptations by an excessive amount of exercise. In support of this concept, in athletes, increased in injuries, unrelated to lactate accumulation and also increased rate of cancer and its mortality, have been linked to prolonged periods of exercise.

Soy protein containing isoflavones can serve as a proper source of antioxidant during exercise and even intense training. In a recent study at the Department of the Human Nutrition at Ohio State University two groups of young, healthy students participated in exercise activities simulating "weekend warrior" behavior for aerobic exercise for 3 weeks, while consuming soy or whey protein. The soy group, but not the whey protein group, showed less exercise – induced muscle tissue breakdown and inflammation after three weeks of regular exercise. These researchers concluded that: "Adding the benefits from the clinically researched soy protein into your diet is a great option, particularly for recreational athletes who tend to push themselves at irregular times."

This study on soy and exercise has been followed by another study in young adult men and women, involved in moderate weight training sessions, during four weeks of soy or whey protein supplementation. The soy protein group again showed a significant positive antioxidant effect following the exercise while the whey protein group showed no effect.

Clinical Studies On The Role Of Soy Protein On Human Athletic Performance

In the past decade several studies have been conducted in US and European Universities and Sport Physiology Research Institutes on the favorable effects of soy protein on lean muscle mass development, performance and chemical markers of the muscle fatigue and more importantly the muscle recovery time following a strenuous training or competition. The results of these studies comparing soy protein to whey protein or casein (milk protein) indicated that soy protein supplementation resulted in positive and measurable effects in strength and endurance and a favorable effect on the chemical markers of the muscle fatigue in athletes who used soy versus other sources of protein. These studies were conducted in both male and female elite, professional athletes such as:

• Olympic Rowers
• Olympic Gymnasts
• Olympic Swimmers
• Olympic Weight Lifters
• Olympic Kayak – canoers
• College athletes as well as recreational exercisers.

Findings of these studies indicated that soy protein consumption during exercise or training sessions resulted in:

• Reduction in muscle fatigue
• Reduced muscle metabolic stress
• Improving muscle recovery component
• Increase in lean muscle mass development
• Reduction in exercise induced muscle injury
• Reduction in muscle inflammation and soreness
• Enhancement in strength indices and therefore,
• Increase in muscular strength and endurance and ultimately enhancing athletic performance.

A brief description of these clinical trials on athletes and their results are as follows:

Twenty-five top female gymnasts participated in a study to examine any changes resulting from 16 weeks of strenuous training and daily supply of soy protein (1gr/kg of body weight). Gymnasts were randomly assigned to one of two groups:

Group A (15 athletes) with soy protein supplementations and Group B (10 athletes) control group. Both groups took part in the same training program. The soy group showed an increase or at least maintained the lean body mass as well as improvement in muscular unit potential while the control group showed a decline in both criteria.14 Most importantly in the soy group there was a decline in the urinary mucoprotein levels (indicating a reduction in muscle fatigue), while there was a significant increase in the control group (indicating an accelerated pace of muscle fatigue).14 After sixteen weeks and a free interval of a four weeks the cross over method was applied (this time Group A was placed on control diet and Group B received the supplemental soy protein). At the end of the second 16 weeks the new soy group showed the similar favorable results as the first soy group.

In another study, the Romanian National gymnast team member’s competitions divided into 2 groups of 7 in the last 16 weeks of their training for the world championship competitions in 1995. One group received (1g/kg/1day of body weight) soy protein supplementation and the remaining 7 were placed on a control diet. The control group showed a significant increase in urinary mucoproteins (indicating accelerated rate of muscle fatigue) while the soy group revealed no change in these chemical markers of muscle fatigue. In addition the athletes in the soy group showed an increase in their lean body mass. Based on these findings and the results of their previous studies these researchers concluded that: the consumption of soy protein may protect the athletes against metabolic muscle stress and fatigue as a results of strenuous exercise and recommended the use of supplementing diet of those athletes with soy protein as a means of "all around preparation" for high level competition and also for faster muscle recovery.

Sixty-six Romanian Olympic endurance athletes (30 kayak-cancer, 36 rowing, both male [45] and female [21]) were divided into two groups. One group (38 athletes) received daily supplementary soy protein for 2 months and the remaining 28 continued on their own diet. The soy group showed an increase in lean body mass (2.5 kg on average) and indices of strength and a significant decline in the chemical markers of muscle fatigue after the training sessions. In a crossover method by switching the diet of the two groups for the second eight weeks, the similar results were found again in the soy protein group. The researcher concluded that based on our favorable findings "we support the idea of the soy protein supplementation for the biological preparation for endurance athletes."

Diet of 43 rowers (23 males and 20 females) members of the Romanian Olympic team was supplemented with soy protein while undergoing strenuous training four to six hours a day. The athletes were randomly divided into two groups. The first group received soy protein for 8 weeks and the second group remained on their regular diet. After one week of wash out, the next eight weeks the groups were switched for receiving the soy protein (cross over method). In both occasions the group who was receiving soy protein had an increase or maintenance of their total body mass as well as a lean body mass and a decline in the chemical markers of muscle fatigue.

In 20 top female swimmers (10 on soy protein, 10 on control) 1.5 gram/kg body weight of soy protein supplementation per day for eight weeks resulted in: 2.6 kg increase in the lean body mass, 1.6% decline in the fat mass and a significant decline in the chemical markers of the muscle fatigue.

Forty-two male and female athletes from the Chinese National Teams (gymnasts, weight lifters and badminton players) were placed on a supplemental soy protein diet. The results indicated a reduction in body fat and an enhancement of strength and improvement in sport ability. In weight lifters soy supplementation created a statistically significant change of he total weight of press on bench, which increased from average of 388.40 kg to 421.82 kg.

Summary

Soy protein has been shown in studies to increase lean body mass, help in muscle recovery and provide energy. Studies have shown that athletes consuming soy protein will increase lean body mass, reduce body fat, reduce muscle inflammation all essential to achieve high performance and winning in competitive sports. These benefits are valued by many including athletes-endurance and strength athletes, recreational athletes and individuals with active lifestyles. The benefits of soy protein are attributed to the unique amino acid profile of soy, the high protein quality and the naturally occurring isoflavones that impart some of the antioxidant properties. During training, the ability to recover from an exercise workout in order to get back into the gym to continue training is essential. Nutritionists and coaches recommend healthful diets with 3 meals and several snacks over the day. More recently supplements such as beverage powders and soy protein bars are used to augment protein and nutrient intakes. Soy protein is now being formulated into many traditional as well as a variety of great tasting everyday familiar foods used as meals and as snacks for everyday living as a great source of energy more specifically high quality and complete protein.

References

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Stroescu V. Dragon I, Georgescu E. Effects of soy protein supplementation in male and female elite rowers. X FINA World Sport Medicine Congress Greece Sept. 17-24, 1994.

Dragon I, Gerogescu E, Iosub I Baloescur. Effects of Soy Protein in top swimmers. IX FINA World Sports Medicine Congress. Kyoto Japan October 1993.

Protein Technology International. Soy protein and human health: Discovering a role for soy protein in fight against coronary heart disease. Houston, Texas; Marimac Communications; 1996.

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Anderson JW, Johnstone BM, Cook-Newell ME. Meta-analysis of the effects of soy protein intake on serum lipids. New England Journal of Medicine 333: 276-282, 1995.

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Polednak AP. College Athletes, body size, and cancer mortality cancer, 38:382-387, 1976.

Rossi Al, Blostein – Fujii A, Di Silvestro R., Soy beverage consumption by young men: Increased plasma total antioxidant status (TAS) and decreased acute, exercise – induced muscle damage. J. Nutraceuticals, Functional and Medical Foods. 3: 33-44, 2000.

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XXVI FIMS World Congress of Sports Medicine Abstract #36, 1998.

Dragon I.C., Stroescu V, Stoian I. Studies regarding the efficiency of SUPRO brand of soy protein in Olympic Athletes. Olympic Scientific Congress. Malaga July 13-17, P62-70, 1992.

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Source: Soy Daily

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