Impact of Acute Circuit Training on Irisin in Younger and Older Overweight Adults.

Abstract

Studies show aerobic exercise increases irisin and leads to health benefits. The impact of circuit training (CT) on irisin in overweight younger and older adults is unknown. The objectives were to determine whether, during an acute bout of CT, changes in irisin differed between overweight younger and older adults, and if irisin is associated with body composition, fitness level, or muscle strength. Inactive, overweight adults aged between 19-35 (25.9 ± 5.0; n=15) and 60-75 years old (67.7 ± 4.1; n=14) participated in this study. The primary exposure variable was an acute bout of CT (12-15 repetitions; 65-70% of 1-repetition maximum; 3 loops). The primary outcome measure was the concentration of irisin determined by ELISA before, during, and after exercise. Repeated measures analyses showed no effect of time on irisin levels during acute CT, and no interaction effect between age and time (p >0.05). No associations were observed between changes in irisin and body composition, fitness, or strength (p >0.05). In conclusion, acute CT doesn t increase irisin in overweight individuals, nor is irisin associated with the measured outcomes. Further studies are needed to elucidate the release of irisin by different types of exercise across the lifespan. NCT03715088 NOVELTY: • Younger and older adults show a similar irisin response to an acute bout of circuit training. • Irisin response is not associated with measures of body composition, cardiorespiratory fitness, nor muscle strength.