Comparison of daily heart rate and heart rate variability in trained and sedentary aged horses.
Authors: Sanigavatee Kanokpan, Poochipakorn Chanoknun, Huangsaksri Onjira, Wonghanchao Thita, Rodkruta Napasorn, Chanprame Sarisa, Wiwatwongwana Thanakorn, Chanda Metha
Journal: Journal of equine veterinary science
Summary
# Editorial Summary Retirement from competition doesn't mean the end of a horse's working life, yet little is known about how continued training affects autonomic nervous system function in aged equines. Researchers compared 22-hour heart rate and heart rate variability profiles between 11 sedentary and 11 regularly trained horses aged 15+ years, monitoring autonomic tone across day and night periods. Trained aged horses exhibited significantly lower resting heart rates and sympathetic nervous system activity during daylight hours, alongside greater parasympathetic dominance and higher heart rate variability (reflected in increased RR interval standard deviation), whilst both groups showed the expected nocturnal shift towards parasympathetic control. These findings suggest that continued moderate exercise in older horses preserves or enhances cardiovascular autonomic balance—a marker of physiological resilience—rather than causing sympathetic overdrive typical of intensive athletic demands. For practitioners managing retired or lightly-worked aged horses, this evidence supports the case for structured low-level activity as a cardiovascular health intervention, though the mechanisms by which exercise volume versus exercise programming modulates this response warrants further investigation.
Read the full abstract on PubMed
Practical Takeaways
- •Maintaining regular exercise programs in retired aged horses promotes better cardiovascular autonomic function and lower resting heart rates compared to sedentary aged horses
- •Trained aged horses show enhanced heart rate variability, indicating improved autonomic nervous system balance and potentially better stress resilience during daytime activities
- •Consider continued light exercise as part of aged horse management protocols, as physical activity appears to modulate autonomic regulation favorably even after retirement from competition
Key Findings
- •Trained aged horses (TAH) demonstrated significantly lower mean heart rate and sympathetic nervous system index compared to sedentary aged horses (SAH) during daytime hours (p < 0.05)
- •Heart rate variability (standard deviation of RR intervals) was higher in TAH than SAH during both day and night periods (p < 0.05)
- •Both groups showed increased RR intervals and parasympathetic nervous system activity at night with decreased heart rate and sympathetic activity (p < 0.01-0.0001)
- •TAH exhibited a shift toward greater parasympathetic nervous system dominance during daytime, suggesting improved autonomic regulation with continued exercise training in aged horses