Effects of isolated soy protein and strength exercise training on exercise performance and biochemical profile in postpartum mice

Objective Postpartum women are at an increased risk for obesity and metabolic diseases because of excessive weight gain during pregnancy and weight retention after delivery. Maintenance of good nutrition and regular physical activity is used as a therapeutic approach for promotion of health and well-being in postpartum women. The aim of this study is to assess the independent and additive effects of isolated soy protein (ISP) and strength exercise training (ET) on weight management, exercise performance and health maintenance in postpartum mice. Design and methods Thirty-two postpartum mice (ICR, 14-weeks old) were divided into four groups (n = 8 per group): Group 1 mice were the sedentary control with vehicle (SC), Group 2 mice were the sedentary control with ISP supplementation (8.95 g·kg−1, SC + ISP), Group 3 mice received vehicle with exercise training (ET) and Group 4 mice received isolated soy protein with exercise training (ISP + ET). Animals in the ET and ISP + ET groups underwent strength exercise training for 6 weeks, 5 days a week. Exercise performance was evaluated by forelimb grip strength and exhaustive swimming time, as well as by changes in body composition and biochemical parameters at the end of the experiment. Results Combined intervention of ISP and ET increased lean muscle mass and prevented body weight and fat elevation. The grip strength and exhaustive swimming time of the ISP + ET group were significantly higher than the other groups. The ISP + ET group showed significantly decreased serum levels of lactate, ammonia and creatinine phosphate kinase (CPK), and increased glucose level after the 15-min swimming test. The serum levels of aspartate transaminase (AST), triglyceride (TG) and creatinine after sacrifice were significantly decreased in the ET + ISP group. ISP combined with ET promoted fat oxidation in brown adipose tissue (BAT) as evidenced from the increased utilization of plasma and BAT tissue triglyceride. Conclusions We suggest that long-term supplementation with ISP can have a wide spectrum of bioactivities on health promotion, performance improvement and fitness. ISP with ET conferred better energy utilization, improved biochemical profiles and may be an effective ergogenic aid in strength training.