Cycling and Running Yield a Similar Myokine and Osteokine Response in Young Adult Females

Abstract

This study examined potential exercise-induced changes in the myokine (irisin), osteokines (sclerostin, osteoprotegerin [OPG]), bone turnover markers (osteocalcin [OC]), and the bonemodulating parathyroid hormone (PTH) in young women following two modes of high-intensity interval exercise of high and low impact. Healthy, recreationally active, females (n=18; 22.5±2.7 years) performed two exercise trials in random order; high-intensity interval running on a treadmill and high-intensity interval cycling on a cycle ergometer. Trials consisted of eight 1- minute running or cycling intervals at ≥ 90% of maximal heart rate, separated by 1-minute passive recovery intervals. Blood samples were collected at rest (pre-exercise), and 5 min, 1h, and 24h following each exercise trial. Irisin, osteocalcin, sclerostin, osteoprotegerin (OPG), receptor activator nuclear factor kappa-β ligand (RANKL), and parathyroid hormone (PTH) were analyzed in serum with post-exercise concentrations being corrected for exercise-induced changes in plasma volume. Irisin was higher than its resting values 24h post-exercise irrespective of impact (time effect, p<0.05), and it was consistently higher during the cycling trial compared to running at all time points (exercise mode effect, p<0.05) with no interaction. A significant time effect was found for sclerostin, PTH, and OC, all of which increased from pre to 5 minutes post-exercise and returned to baseline levels by 1 hour post-exercise, with no difference between exercise modes and no exercise mode-by-time interaction. OPG also showed a significant main effect for time, reflecting an overall increase at 5 minutes and 1 hour following high-intensity interval exercise irrespective of exercise mode, which was not significant after the Bonferroni adjustment. In conclusion, these results provide evidence that in young women, a single bout of high-intensity exercise induces an immediate increase in upstream and downstream regulators of bone remodeling, and a later response in irisin concentrations. These findings support the concept of bone-muscle crosstalk during exercise independent of the impact of gravity loading.