Importance of lean body mass to endurance and functional capacity in the elderly

Age-related changes in lean body mass (LBM) and maximal attainable aerobic power (VO₂max) were assessed in 72 young (Y; 20-30 yr), 459 young-old (YO; 60-75 yr), and 112 old-old (OO; 78+ yr) women and men. The elderly subjects were all functionally independent. Body weight was 62±12, 70±13, and 63±13 kg in Y, YO, and OO women, respectively, and 75±10, 83±12, and 79±12 kg in Y, YO, and OO men, respectively. LBM was 47*7 kg, 42±6 kg, and 38±5 kg in Y, YO, and OO women, respectively, and 63±7 kg, 60±7 kg, and 55±5 kg in Y, YO, and OO men, respectively. VO₂max was 36±5, 20±3, and 15±3 mL/min/kg in Y, YO, and OO women, respectively, and 48±5, 27±4, and 17±4 mL/min/kg in Y, YO, and OO men, respectively. VO₂max (L/min) was associated with LBM (r = 0.81, p<0.001), suggesting that very low levels of LBM may limit endurance capacity of elderly women. In the OO group, LBM was a significant determinant of the ability to get up from a chair (r=0.61, p<0.01) and to ascend stairs (r=0.54, p<0.01), indicating that adequate muscle mass is necessary to perform these strength- dependent tasks. These findings suggest that strategies for increasing or at least maintaining LBM in the elderly may help to preserve the endurance and functional capacity required for independent living.