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
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;