Effect of acute downhill running on bone markers in responders and non-responders

Summary: This study showed that procollagen type 1 amino-terminal pro-peptide and N-MID osteocalcin significantly increased after exercise independent of the form of muscle contraction. Thus, these preliminary results will be useful for future studies that will consider bone turnover characteristics of responders and non-responders to acute and chronic aerobic exercise.
Introduction: The aim of the current study was to compare the effects of acute flat running (FR) and downhill running (DHR) on bone turnover markers in men.
Methods: Fourteen healthy young active men performed three exercise tests in a ounterbalanced order, including rest condition, FR, and DHR, at 60% maximal aerobic capacity on a treadmill with 0 and − 12% inclines. Blood samples were taken in the preexercise,
immediately post-exercise, and 24-h post-exercise periods, and bone markers included total procollagen type 1 aminoterminal pro-peptide (total PINP) and N-MID osteocalcin.
Results: Total P1NP significantly increased after exercise independent of the form of muscle contraction (p > 0.05). N-MID osteocalcin increased after DHR by 17% compared to after pre-exercise, but the difference did not reach significance (p =0.07; partial eta square, 0.21). Biomarker responses to exercise were dependent on the exercise form and independent of hormone type in half of the participants who were classified as responders. Physiological parameters and changes in muscle voluntary contraction did not explain the differences between responders and non-responders.
Conclusion: The effect of acute DHR on bone turnover is determined by biomarker type and participant characteristics. Future studies should discriminate between the characteristics of responders and those of non-responders.