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Relationship between body composition, blood volume and maximal oxygen uptake
C F Kearns1, K H McKeever, H John-Alder
1Equine Science Center, Rutgers, The State University of New Jersey, 08901, USA.
Equine Veterinary Journal. Supplement
|October 31, 2002
Summary
Maximal oxygen uptake (VO2max) in horses is linked to lean body mass, not just overall weight. Fat-free mass and red blood cells from splenic reserves are key factors for athletic performance.
Area of Science:
- Equine physiology
- Exercise science
- Animal sports medicine
Background:
- Lean body mass is a known determinant of maximal oxygen uptake (VO2max) in humans and animals.
- Limited data exists on the relationship between body composition and VO2max in horses.
Purpose of the Study:
- To investigate the correlation between body composition and VO2max in Standardbred mares.
- To determine if lean body mass influences VO2max independently of total body mass.
Main Methods:
- Twenty-three unfit Standardbred mares underwent incremental exercise testing to determine VO2max.
- Rump fat thickness (RTH) measured via ultrasound; plasma volume, total blood volume, and red cell volume determined using dye dilution and packed cell volume.
- Regression analysis performed on mass-residuals to isolate independent effects of variables on VO2max.
Main Results:
- VO2max correlated with body mass and exercise hematocrit (exHCT), but not RTH.
- After accounting for body mass, VO2max residuals showed a negative correlation with RTH residuals and a positive correlation with exHCT residuals.
- A combination of RTH and exHCT residuals predicted VO2max (r = 0.767, P<0.0001).
Conclusions:
- VO2max in horses is significantly related to fat-free mass (FFM), independent of body mass.
- Red blood cells from splenic reserves are crucial for achieving high VO2max.
- Lean body mass is a more appropriate metric for assessing metabolic function in athletic horses.