How does soy protein aid sports performance?

A person's ability to sustain high-intensity exercise is assessed by measuring 'VO2 Max', which is the maximum amount of oxygen taken up by a person exercising under a certain set of conditions. An improvement in VO2 Max is generally accompanied by an enhancement of physical strength and performance.

Dr. Husaini from the Nutrition Research and Development Centre in Indonesia ¹ recently demonstrated that young male and female elite badminton players aged 10 to 14 years, given a soy protein based, nutrient rich beverage compared to a carbohydrate beverage control, had improved levels of VO2 Max and iron. The greatest improvement in VO2 Max was after four months of consuming the soy protein based beverage. The badminton players' improvement in VO2 Max was accompanied by an increase in physical strength and performance.

Researchers from the Institute of Sports Medicine in Romania ² , ³ found that in Olympic athletes consuming a protein-rich diet, the use of soy protein may reduce fatigue after training sessions. Their studies with the Romanian Olympic Rowing Team showed that an intake of soy protein at 1.5g per kg body weight in addition to the regular intake of protein in the diet (2.0g per kg body weight) may be beneficial in reducing fatigue after an exercise session ³ .

The naturally occurring isoflavones in soy have been shown to act as antioxidants in the body ^4-8 . Antioxidants are thought to 'neutralise' free radicals, which are unstable compounds that develop during normal metabolic processes and during periods of 'oxidative stress', such as exercise. These compounds may contribute to the fatigue, soreness and muscle injury that occurs with exercise ⁵ .

Dr. Robert DiSilvestro ⁹ from Ohio State University, USA, recently studied 20 healthy athletic college males who, in addition to their usual diet, consumed either 40 grams of soy protein with the naturally occurring isoflavones or 40 grams of whey protein as a control. The men consuming the soy protein showed an increase in their body's total antioxidant status (TAS), while the group fed whey did not experience any increase in TAS. This rise in the body's TAS was associated with a reduction in the level of certain enzymes in blood, which are indicators of muscle damage and inflammation. (Muscle damage and inflammation in athletes are a result of oxidative stress).

Dr. DiSilvestro noted that consumption of soy protein with its naturally occurring isoflavones may help protect the exercising individual against oxidative stress and resulting muscle injury and inflammation. Based on these research findings the routine use of soy protein in the daily diet may support long and hard training sessions, by shortening recovery time.