Six weeks of combined aerobic and resistance exercise using outdoor exercise machines improves fitness, insulin resistance, and chemerin in the Korean elderly: A pilot randomized controlled trial

Background: The aim of this study was to investigate the effect of a six-week-long exercise program using outdoor exercise equipment on fitness, insulin resistance and adipocytokines among Korean elderly. Methods: A total of 47 participants were randomized into one of the following three groups; control, resistance exercise or combined exercise (aerobic and resistance exercise). The resistance exercise group completed three resistance types of exercise. The combined exercise group completed five exercises, including three resistance types of exercise and two aerobic types of exercise. Participants' body composition, fitness level, homeostasis model assessment of insulin resistance (HOMA-IR), and adipocytokines were measured at baseline and at the end of six weeks. Results: After six weeks of exercise training, participants in the combined exercise group exhibited significant reduction in insulin, HOMA-IR and chemerin levels, while significant reduction was observed in HOMA-IR only in the resistance exercise group compared with the control group. Meanwhile, six weeks of exercise training, whether resistance exercise alone or combined, significantly improved upper body muscular strength/endurance and physical function compared to the control group. Conclusions: Six weeks of combined exercise using outdoor exercise equipment was effective in improving fitness, HOMA-IR, circulating chemerin levels, and other known risk factors of chronic diseases.