Comparative efficacy of exercise and nutritional interventions on serum IGF-1 levels in older adults with frailty and/or sarcopenia: A systematic review and network meta-analysis

To compare and rank exercise, nutritional supplementation, and combined interventions on serum insulin-like growth factor-1 (IGF-1) in older adults with sarcopenia and/or frailty.We searched English (Web of Science, Cochrane, PubMed, EMBASE, Scopus) and Chinese (CNKI, Wanfang) databases for randomized controlled trials (RCTs). Interventions were categorized as Control, Nutrition, Aerobic Training (AT), Resistance Training (RT), Combined Training (CT), RT+Nutrition, and CT+Nutrition. A frequentist random-effects network meta-analysis (NMA) was performed in Stata 15.0 and R. Standardized mean differences (SMDs) with 95% confidence intervals (CIs) were calculated; interventions were ranked using the Surface Under the Cumulative Ranking curve (SUCRA).Nineteen RCTs were included. Versus control, CT (SMD = 0.53, 95% CI: 0.07-0.99) and RT (SMD = 0.47, 95% CI: 0.11-0.84) significantly improved IGF-1. RT+Nutrition had the largest but non-significant effect (SMD = 0.89, 95% CI: -0.02-1.80). RT+Nutrition ranked highest by SUCRA (87.6%), followed by CT (73.9%) and RT (68.6%). GRADE certainty was low to very low, mainly due to risk of bias and imprecision.RT plus nutrition ranked highest for elevating IGF-1, but its effect versus control was non-significant and evidence certainty was low to very low. These findings require cautious interpretation and do not establish superiority.