Fermented soybean beverage improves performance and attenuates anaerobic exercise oxidative stress in Wistar rat skeletal muscle

Abstract

BackgroundHigh intensity exercises can damage active muscles due to mechanical and oxidative stress. Dietary supplements can mitigate muscle damage, especially vegetable products with high content of antioxidant compounds, such as soybean. We aimed to evaluate the effects of a fermented soy-based beverage on oxidative stress and exercise performance in animals submitted to resistive exercise. MethodsThe soybean fermented product was prepared with soybean extract fermented by Kefir grains and then the content of flavonoids, phenolic compounds and antioxidant activity were analyzed using the ABTS test. Animals were divided into sedentary (control-C, soybean-S, and soybean-kefir-SK) and exercised (exercise-E, soybean-SE, and soybean-kefir-SKE) groups. After 8 weeks of treatment all animals were euthanized. ResultsBlood lactate was high (>7 mmol/l) in all exercised groups. The SKE group performed the highest number of jumps in training sessions, when compared to the other groups (E: 28.20 ± 2.29; SE: 29.20 ± 2.72; SKE: 41.27 ± 1.76; jump/min; p < 0.05). In addition, the SKE group developed hypertrophy of the gastrocnemicus muscle (E: 1.46 ± 0.003; SE: 1.46 ± 0.005; SKE: 1.51 ± 0.005; g/cm; p < 0.05), with less oxidative stress. The soybean fermented beverage had a high antioxidant effect (SK IR50: 4.13 ± 0.57; S IR50: 6.53 ± 0.35; p < 0.05) and increased flavonoids content (SK: 0.96 ± 0.04 mg/g; S: 0.095 ± 0.038 mg/g; p < 0.01). ConclusionHigh flavonoids content soy-based drink fermented with kefir blunted oxidative stress on skeletal muscle, resulting in improvement of the physical performance in animals trained through high intensity anaerobic exercise.