Wen, Z. K., Hsu, S.-Y., Huang, .Z-M., & Chang, W.-H. (2014). Effect of a pre-exercise soy protein bar supplement on exercise performance. Medicine & Science in Sports & Exercise, 46(5), Supplement abstract number 379.

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“Nutritional supplementation prior to exercise has been shown to affect metabolic responses and performance. Low muscle glycogen stores result in physical fatigue and the body’s inability to complete high intensity exercise. Soy protein bar has a low glycemic index (GI=9.4) and rich in polyphenol compounds (such as isoflavones and flavanoids), which are important for sustaining carbohydrate availability during exercise and prevent the exercise-induced oxidative stress and muscle damage”.

This study determined if exercise performance, energy metabolic parameters (e.g., glucose, lactate, ammonia), and post-exercise muscle damage (creatine phosphokinase) were altered when consuming two soy protein bars before exercise in healthy sports students (M = 14; F = 3). Ss were randomized to consume either two soy protein bar + water or water only (Control group) 30 minutes prior to exercise. Ss performed a continuous bout of exercise [30-minute treadmill run at 70% maximum heart rate] and then the running speed was increased by 1 km/hour every minute until exhaustion. Rating of perceived exertion and heart rate were recorded every three minutes during exercise. After exhaustion, fatigue onset time was also recorded. Blood samples were drawn before, during, and at 0, 30, 60, and 90 minutes after exercise.

Soy protein bar consumption significantly reduced serum creatine phosphokinase levels to a much greater degree than in the control group. There were significant main effects of soy protein intervention and exercise on blood glucose concentration. Decreased serum ammonia, lactate levels, and rating of perceived exertion and running time were not statistically significant between the two groups.

Implication. Pre-exercise soy protein bar consumption stabilizes blood glucose level and minimize muscle damage after exercise in healthy sports students.

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