Abstract
Objectives—To establish maximum oxygen consumption
(
O2max) in ponies of different body
weights, characterize the effects of training of short
duration on O2max, and compare these effects to
those of similarly trained Thoroughbreds.
Animals—5 small ponies, 4 mid-sized ponies, and 6 Thoroughbreds.
Procedure—All horses were trained for 4 weeks.
Horses were trained every other day for 10 minutes
on a 10% incline at a combination of speeds equated
with 40, 60, 80, and 100% of O2max. At the beginning
and end of the training program, each horse performed
a standard incremental exercise test in which
O2max was determined. Cardiac output (
), stroke
volume (SV), and arteriovenous oxygen content difference
(C [a-v] O2) were measured in the 2 groups of
ponies but not in the Thoroughbreds.
Results—Prior to training, mean O2max for each
group was 82.6 ± 2.9, 97.4 ± 13.2, and 130.6 ± 10.4
ml/kg/min, respectively. Following training, mean
O2max increased to 92.3 ± 6.0, 107.8 ± 12.8, and
142.9 ± 10.7 ml/kg/min. Improvement in O2max was
significant in all 3 groups. For the 2 groups of ponies,
this improvement was mediated by an increase in ;
this variable was not measured in the Thoroughbreds.
Body weight decreased significantly in the
Thoroughbreds but not in the ponies.
Conclusions and Clinical Relevance—Ponies have a
lower O2max than Thoroughbreds, and larger ponies
have a greater O2max than smaller ponies. Although
mass-specific O2max changed similarly in all groups,
response to training may have differed between
Thoroughbreds and ponies, because there were different
effects on body weight. (Am J Vet Res 2000;
61:986–991)
