Relationship between body composition, blood volume and maximal oxygen uptake.

This study focuses on examining the relationship between body composition and maximal oxygen uptake (VO2max) in horses. The findings indicate that VO2max in a horse is significantly related to its fat-free mass, with lean body mass being a more appropriate basis for assessing its metabolic function.

Research Methodology and Subjects

• The research was carried out with the participation of 23 physically unfit but healthy Standardbred mares.
• Body mass and fat cover, also known as Rump fat thickness (RTH), were measured in these horses.
• RTH is considered as a measure of body fat and was measured using B-mode ultrasound.
• The blood composition of the subjects including plasma volume, total blood volume, and red cell volume were determined through the Evan’s Blue dye dilition technique and packed cell volume.
• An incremental exercise test (GXT) was also performed on the subjects to measure their VO2max, the maximum rate of oxygen consumption measured during incremental exercise.

Key Findings

• The study found a correlation between VO2max and body mass, and exercise haematocrit (exHCT), but not between VO2max and RTH or other haematological variables.
• To eliminate the influence of body mass on the individual variables, a regression analysis was performed on the mass-residuals of VO2max, RTH, plasma volume, and exHCT.
• VO2max was found to be negatively correlated with the residuals of RTH and positively correlated with residuals of exHCT.
• The research found that VO2max could be predicted from a linear combination of the residuals of RTH and exHCT.

Conclusions and Implications

• The study concludes that VO2max in horses is significantly related to their fat-free mass (FFM), regardless of their body mass.
• It has also been found that red blood cells from the splenic reserve constitute an important factor in the horse’s ability to achieve a high VO2max.
• This suggests that lean body mass may be a more accurate basis for assessing the metabolic function in athletic horses.

It signifies that strategies to optimize the lean mass of horses might lead to improvements in their VO2max and, consequently, their performance in exercise or athletic pursuits. This finding, as a result, could have significant implications for the management of equine athletes.