The energetic cost of some daily activities: a comparison in a young and old population

We compared the energetic costs of some daily activities in two groups, 10 young people (24.3 +/- 2.8 years) and 10 old people (74.4 +/- 2.2 years): rising and sitting back down on a seat, getting up from and lying down on a bed and getting up from the floor. We measured the oxygen consumption and the time necessary for the activities. The results showed a noteworthy economical energetic procedure when rising and sitting back down on a seat among the older group. The values of the energy expenditure were respectively 3.9 +/- 1.3 cal/kg in the older group and 5.8 +/- 1.6 in the younger one with a standard seat (45 cm) and 2.7 +/- 1.2 vs 5.2 +/- 1.5 with a raised seat (60 cm). The activities did not vary significantly in time in the two age groups. This procedure could be understood as an adaptation of the energy expenditure to the reduced aerobic capacity with ageing. Conversely, getting up from and lying down on the floor or a standard hospital bed involved the same energy expenditure in the older and younger group, but performing these activities took significantly longer for the older people (+60% for getting up from the floor, +33% from the bed). As these activities revealed no economical energetic procedure in the older group, they appeared responsible for a strong factor of dependence. The importance of a learning process particularly for the most usual movements in everyday life is discussed.