Inter- and intrastrain variation in mouse critical running speed.

With the generation of mouse models of human cardiovascular or neuromuscular disorders, the development of noninvasive methods to evaluate the physiological responses to exercise presents an important challenge. The possibility for determining critical speed (CS) in the mouse model was examined according to strain (CD1, C57BL/6J, FVB/N) and sex. Sixty mice performed four exhaustive runs on a treadmill to determine their CS. Twenty-one performed an incremental test to determine the velocity at the lactate threshold. CS was significantly different between the strains (P < 0.0001) but not between sexes. Two measures of heritability showed that CS was partially heritable. CS was not significantly different from lactate threshold velocity. We conclude that CS, which reflects the aerobic capacity, can be determined in mice, as in humans and horses. Considering the intrastrain variability, CS could represent a valuable means for designing an optimal and individualized physical training in mice.