Purpose: This study examined whether the exercise-induced changes in inflammatory cytokines differ between impact and no-impact high-intensity interval exercise, and whether they are associated with postexercise changes in sclerostin.
Methods: Thirty-eight females (n = 19, 22.6 ± 2.7 yr) and males (n = 19, 22.3 ± 2.4 yr) performed two high-intensity interval exercise trials in random order (crossover design): running on a treadmill and cycling on a cycle ergometer. Trials consisted of eight repetitions of 1 min running or cycling at ≥90% maximal heart rate, separated by 1 min passive recovery intervals. Blood was collected preexercise and 5 min, 1 h, 24 h, and 48 h postexercise, and it was analyzed for serum levels of interleukins (IL-1β, IL-6, and IL-10), tumor necrosis factor alpha (TNF-α), and sclerostin.
Results: Inflammatory cytokines significantly increased over time in both sexes with some differences between trials. Specifically, IL-1β significantly increased from pre- to 5 min after both trials (23%, P < 0.05), IL-6 increased 1 h after both trials (39%, P < 0.05), IL-10 was elevated 5 min after running (20%, P < 0.05) and 1 h after both running and cycling (41% and 64%, respectively, P < 0.05), and TNF-α increased 5 min after running (10%, P < 0.05). Sclerostin increased 5 min after both trials, with a greater increase in males than that in females (62 vs 32 pg·mL in running, P = 0.018; 63 vs 30 pg·mL in cycling, P = 0.004). In addition, sclerostin was significantly correlated with the corresponding changes in inflammatory cytokines, and 34% of the variance in its postexercise gain score (Δ) was explained by sex and the corresponding gain scores in TNF-α, which was the strongest predictor.
Conclusion: A single bout of either impact or no-impact high-intensity exercise induces changes in inflammatory cytokines, which are associated with the postexercise increase in sclerostin.