Monitoring the effects of treadmill exercise on bone by non-invasive means during a progressive fitness programme.

The research study investigates the impact of a progressive treadmill exercise program on the bone health of six Standardbred horses, using non-invasive monitoring methods such as ultrasound. Significant increases were observed in ultrasound velocity through the third metacarpus and modulus of elasticity due to the training, despite no changes in bone mineral content, bone mineral density, or compact bone density.

Methods

• The researchers conducted a 14-week training program involving six Standardbred horses. The exercise regimen was performed on a treadmill.
• The training program incorporated two phases: a five-week slow work phase (consisting of six to 12 km/day at a speed of 5 m/sec) and a nine-week interval phase which progressively increased in intensity.
• During the last three weeks of the interval phase, the horses performed three to four intervals per day ranging between 600 to 1000 m at or above maximum heart rate.

Results

• Through non-invasive ultrasound monitoring, the study found a significant increase in ultrasound velocity passing through the third metacarpus due to training. This showed that the training contributed to changes in bone structure or quality.
• A significant increase in modulus of elasticity, a measure of a material’s (in this case, bone’s) resistance to being deformed when a stress is applied, was also observed. This suggested that the bones became harder and less prone to deformation as a result of the training program.
• However, the study found no changes in bone mineral content, bone mineral density, or compact bone density through the 14-week training program. These are significant factors in determining bone strength and resistance to fractures.
• A reduction in ultrasound velocity was recorded immediately after a session of trotting on the treadmill for 6 km. This transient effect might suggest a temporary alteration in the bone’s structure upon exercising but needs further investigation to draw significant conclusions.

Conclusions

• The study found that treadmill exercise modifies the viscoelastic properties of the horses’ cortical (outer) bone over a sustained period. These changes indicate potential benefits of exercise on bone health, possibly reducing risks associated with fractures and other bone-related injuries.
• However, the mechanism explaining these observed changes in bone structure and properties remains unclear and warrants further exploration.