Exercise intensity affects circulating C1q/TNF‐related proteins and follistatin‐like 1 concentrations

Background Individuals who engage in high‐intensity endurance exercise reportedly have a lower rate of mortality from metabolic diseases than do those who engage in moderate‐intensity endurance exercise. However, the mechanisms underlying this association remain unclear. The cytokines C1q/tumour necrosis factor‐related protein (CTRP) 3, CTRP9, and follistatin‐like 1 (FSTL1) improve metabolic diseases. The secretion of these circulating cytokines is enhanced through acute endurance exercise; however, the effects of exercise intensity on this secretion have not been elucidated. We investigated the effect of exercise intensity on the circulating CTRP3, CTRP9, and FSTL1 concentrations. Methods Ten healthy men performed three experimental trials—moderate‐intensity cycling (MIE; 50% maximal oxygen uptake), high‐intensity cycling (HIE; 75% maximal oxygen uptake), and control (Con; rest)—in a crossover design. The duration of the exercise trials was varied to match the total energy expenditure between the trials. Blood samples were collected before exercise and at 0 (immediately after exercise) and 120 min after exercise. Circulating CTRP3, CTRP9, and FSTL1 concentrations were measured. Results In the HIE trial, significant increases in the circulating concentrations of CTRP3, CTRP9, and FSTL1 were observed after exercise compared to before exercise; however, no significant increases in these cytokines were observed in the MIE trial. Moreover, the increased ratios of the CTRP3, CTRP9, and FSTL concentrations after exercise compared to those before exercise were higher only in the HIE trial compared to the Con trial. Conclusion These findings indicate that circulating CTRP3, CTRP9, and FSTL1 concentrations are affected by exercise intensity during endurance exercise, increasing only after high‐intensity exercise.