Physical activity and subsistence pattern of the huli, a Papua New Guinea highland population

Several studies on human energetics have been conducted in developed and de veloping countries, but very few simultaneously measured time use and energ y expenditure. Only a few quantitatively compared subsistence patterns betw een rural and urban dwellers of an identical population. Here we present th e daily physical activity level (PAL), physical exertion, time, and energy expenditure in contrasting subsistence/occupational activities of Papua New Guinea Highlanders, comparing 27 rural villagers (15 men, 12 women) who ma intained traditional subsistence agriculture, with 29 urban migrants (14 me n, 15 women) who engaged in cash-earning work. A large sex inequality in th e division of labor was noted between rural males and females, but not amon g urban dwellers. Rural-urban comparison indicated sex differences in urban ization. For urban men, the reduction of physical exertion level during wor k, from energy-consuming agricultural work to sedentary cash-earning work, together with significantly extended work time (by 261 min/day, P < 0.001), led to an increase in work energy expenditure (15-29% of PAL). In contrast , urban women who spent almost equal time at work relative to rural women s howed a lower energy expenditure (18% compared to 26% of PAL). The associat ions with urbanization included a gain in body weight (by 6.4 kg for either sex) and reduced PAL (by 7%, not significant in men; 13%, P < 0.01 in wome n). Further research is needed to elucidate the effects of urbanization on time use, energy expenditure, and PAL, by comparing rural residents with ur ban migrants in the same population. (C) 2001 Wiley-Liss, Inc.