The effect of resistance training on endothelial function in young and older with chronic diseases and those with health conditions: a systematic review and meta-analysis

Endothelial dysfunction plays an important role in the development of cardiovascular diseases. Exercise training may lead to improved endothelial function. However, the effect of resistance training on endothelial function is not clearly understood. In addition, the age and health status of individuals may also play a role in endothelial function, and these factors have not been investigated in endothelial response to resistance training. Therefore, the aim of the present meta-analysis is to investigate the effect of resistance training on endothelial function in young and older adults with and without chronic diseases.

Main databases including PubMed and Web of Science were searched through January 13, 2023, for resistance training studies on the FMD index. The inclusion criteria for the current research included studies with an exercise training group, human subjects with an average age older than 18 years, measuring endothelial function using FMD, and published in English and Persian language journals. Weighted mean difference (WMD) and 95% confidence interval were used to determine the effect size using CMA2 software. The level of heterogeneity was assessed using the I2 test and the publication bias was also assessed with Egger's test. Subgroup analyses were performed for age (elderly adults including people over 50 years old and young adults including people under 50 years old), health status (with chronic disease and healthy), and type of study (one-group and two-group). All analyzes were performed using CMA2 software.

Twenty-one studies including 701 participants were included in the meta-analysis. The results of data analysis showed that resistance training resulted in a significant increase in FMD [2.07, (CI: 1.26 to 2.88) P = 0.001]. Examination of heterogeneity using the I2 test showed that there was a significant heterogeneity (I2=82.92, p=0.001), while Egger's test results (p=0.73) did not confirm the publication bias. Subgroup analysis based on age showed that resistance training in both groups of young [WMD: 2.06, P = 0.001] and older [WMD: 1.87, P = 0.001] individuals leads to an increase in FMD. In addition, resistance training in both groups of healthy [WMD: 1.770 P = 0.001] and patients [WMD: 2.406 P = 0.001] individuals lead to an increase in FMD. In addition, the analysis based on the type of study showed that FMD is increased in both single-group [WMD: 1.18, P = 0.029] and two-group [WMD:2.51, P  =0.001] studies.

In general, the main findings of the present meta-analysis show that resistance training is an effective exercise intervention for improving endothelial function, whose beneficial effects occur independently of the age and health status of adults. Therefore, resistance training should be included in the exercise program for adults.