The effect of a mixed circuit training on muscle synthesis’s indices, neurotrophic factors, and physical fitness in elderly women: A randomized controlled trial

Abstract Background: Regular physical activity can improve muscle synthesis, cognitive function, and physical fitness and consequently delay the side effects of aging. However, the effect of circuit training which is a combination of resistance and aerobic exercise is still unknown. Therefore, this study aimed to evaluate the effect of 8 weeks of a mixed circuit of aerobic and resistance training on serum levels of muscle synthesis indices, neurotrophic factors, and physical fitness in elderly women. Methods: A total of 24 healthy elderly females (age 65±3 years) were recruited and randomly divided into two groups as follows: Mixed Circuit Training (MCT, n=12) and Control (C, n=12). Participants in the MCT group performed circuit training (three times a week at an intensity of 40-60% of 1 repetition maximum) for 8 weeks. Participants in the C group did not received any intervention. Serum levels of growth hormone (GH), Insulin-like growth factor-1 (IGF₁), brain derived neurotrophic factor (BDNF), nerve growth factor (NGF), and physical fitness (cardiovascular fitness, muscular endurance, and balance) were measured before and after the eight weeks of intervention. Results: Serum levels of GH, IGF-1, BDNF, and, NGF were increased in the MCT group after eight weeks (p ˂0. 001). Cardiovascular fitness, muscular endurance, and balance were also improved in the MCT group after eight weeks of intervention (p ˂0. 001). Conclusions: A mixed circuit training could improve muscle synthesis, neurotrophic factors, and physical fitness in elderly women. To confirm these results, further studies are recommended. Trial registration Retrospectively registered. IRCT20240108060648N1. Registration date: 2024/02/12. URL: https: //irct. behdasht. gov. ir/search/result? query=IRCT20240108060648N1