Cold exposure increases running V over dotO(2) max and cost of transport in goats

We inadvertently subjected a group of goats to 5 mo of cold exposure (mean minimum temperature less than -13 degreesC) during an experiment designed t o examine the effects of training by daily running on one member of each si bling pair. During the three coldest months, the sedentary but cold-exposed goats experienced a 34% increase in maximal oxygen uptake ((V) over dot O- 2max,O- P< 0.01) and a 29% increase in running speed at maximal (P< 0.05). When temperatures increased in the spring, both oxygen uptake and running s peed decreased. We interpret these findings as evidence that cold is a suff icient stimulus to invoke the development of aerobic structures in muscle a nd that these structures subsequently can be utilized for the novel task of running. When the experiment was subsequently repeated without the cold ex posure, running speed and (V) over dot O-2max of trained animals increased less than in either group of cold-exposed animals. However, the cost of tra nsport of these warm runners was lower than either group of cold-exposed an imals (from 13-19%, P< 0.0001). Thus, although aerobic capacity was increas ed with acclimation to severe winter weather, cold-acclimated goats operate d with lower efficiency during locomotion.