Table 7.

Effects of age and body composition (lean tissue and fat) onO2max andO2sum in deer mice younger and older than the `breakpoint' age of 485 days

Young mice (<485 days) Old mice (>485 days)
VariableFat and lean (absolute values)Fat and lean (fractions of body mass)Fat and lean (absolute values)Fat and lean (fractions of body mass)
O2max Fatr=0.509, P=0.013r=0.237, P=0.289r=0.481, P=0.0096r=0.152, P=0.449
Leanr=0.397, P=0.060r=0.174, P=0.439r=0.346, P=0.0708r=0.231, P=0.245
Ager=0.207, P=0.344r=0.055, P=0.808r=0.264, P=0.174r=0.425, P=0.027
O2sum Fatr=0.360, P=0.091r=0.155, P=0.491r=0.121, P=0.582r=-0.225, P=0.259
Leanr=0.466, P=0.025r=0.132, P=0.557r=0.065, P=0.767r=-0.289, P=0.143
Ager=0.113, P=0.608r=0.003, P=0.989r=-0.370, P=0.083r=-0.399, P=0.039
  • O2max, maximal oxygen consumption in exercise; O2sum, maximal oxygen consumption in thermogenesis.

    Regressions were performed on animals younger and older than the `breakpoint' age of 485 days determined from the complete data set. Regression coefficients (r) and P values for fat and lean tissue content were computed from absolute tissue mass and as fractions of whole body mass; in the latter case, regressions also included whole body mass (r and P values not shown). No P value is significant after Bonferroni correction (adjusted α=0.0023 for young and old mice).