Response of serum biochemical markers of bone metabolism totraining in the juvenile racehorse

Sixteen Quarter Horse-type geldings were used to examine the response of biochemical markers of bone metabolism to forced exercise prior to and during race training. The study began when the average age of the horses was 15 months. Horses were exercised on a high-speed treadmill for 14 weeks, and were subsequently placed into race training. Serum was collected and assayed for concentrations of osteocalcin (BGP), the carboxyterminal telopeptide of type I collagen (ICTP) and the carboxyterminal propeptide of type I procollagen (PICP). When data were normalized from the onset of race training, ICTP and PICP concentrations were higher in the pre-exercised horses (P<.05 and P<.1, respectively) indicating higher rates of bone turnover. Overall, bone turnover appeared to be decreased during race training, as concentrations of PICP and ICTP were lower when compared to values seen during the pre-training Phase.