Evaluation of serum concentrations of biochemical markers of bone metabolism and insulin-like growth factor I associated with treadmill exercise in young horses.

This study investigates the impact of treadmill exercise on the levels of certain biochemical markers (related to bone metabolism) and insulin-like growth factor I (IGF-I) in young horses. The findings suggest that over a 20-week period, regular treadmill exercise may lead to beneficial adaptations in a horse’s bones, such as increased bone mineral density and content, decreased levels of certain bone turnover markers, and a correlation between changes in IGF-I and bone cell activity.

Research Context and Methodology

• The study was conducted with 12 two-year-old Thoroughbred mares over a period of 20 weeks.
• Half the horses (the exercise group) exercised three times a week on a treadmill, while the other half (the control group) received daily walking exercise, six days a week.
• The study monitored changes in serum concentrations or activity of biochemical markers and insulin-like growth factor I (IGF-I) associated with bone metabolism. These assessments were conducted biweekly.
• The researchers measured the bone mineral density and content of the first phalanx (the proximal or first bone in the hoof or ‘toe’) using dual-energy X-ray absorptiometry (DEXA) upon completion of the study.

Findings and Results

• The study found that horses in the exercise group had higher bone mineral density and content than their control counterparts.
• Also, serum concentrations of osteocalcin (a marker of bone formation) and the carboxy-terminal telopeptide of type I collagen (ICTP, a marker of bone resorption) were lower in the exercised horses.
• The bone formation markers carboxy-terminal propeptide of type I collagen and bone-specific alkaline phosphatase (BAP) showed no significant differences between the two groups.
• In terms of growth factors, the researchers found that the serum IGF-I concentration was lower in the exercise group than in the control group. They also found a significant correlation between changes in IGF-I values and changes in osteocalcin, ICTP, and BAP values at the end of the study.

Conclusions and Implications

• The research concludes that treadmill exercise over 20 weeks induced beneficial changes in the bones of two-year-old Thoroughbreds. Specifically, it appears that training can increase bone mineral density, thereby improving the mechanical strength of bone. At the same time, it also appears to reduce bone turnover.
• The results indicated a connection between changes in serum IGF-I concentration and bone cell activity in horses.
• Understanding these relationships can help us understand how exercise influences the bone health of not just horses, but potentially other animals and humans as well.