Fig. 2.

Temperature effects on tail and femur length in wheel-running and non-wheel-running mice. A: tail lengths confirmed previous findings that extremities are shorter at cold temperatures. There was a significant and sizable temperature effect on tail elongation (2-way ANOVA: F = 216.3, P < 0.001) but no effect of wheel-running exercise. Change in tail length in the cold mice measured only half of that in the warm groups, regardless of exercise. B: femur length varied with temperature and exercise. Conclusion is that the exercise effect was localized to limb bones and was not a systemic or endocrine reaction. Femur is plotted as change in length from a common baseline starting point, determined by average femur length of 8 mice at 24 days age. Tail is plotted as change in length from the start, measured for each individual mouse. Values are group means ± SE. Statistically significant (P < 0.05) by 1-way ANOVA and Tukey's test for multiple independent comparisons: *WW and WN vs. CW and CN in pairwise comparisons; +WW > WN and WW > CN; ++CW > CN.