Maximum weights of handling acceptable to people aged 55-74 years: Part II. Carrying

Part I dealt with dynamic psychophysical strengths of the older population for manual lifting activities. Part II deals with dynamic psychophysical st rengths of the older population for manual carrying activities (maximum acc eptable weight of carry-MAWC). Subject population that participated in the manual carrying activities was the same that participated in manual lifting activities (ten males and ten females in each of the two age groups-55-74 years of age and 18-35 years of age). A questionnaire was,as used to identi fy carrying activities routinely performed in and around the home and workp lace,. Thl ee of these activities were simulated in the laboratory settings , and included a two-handed carrying task, a one-handed carrying task, and bag carrying. All carrying activities were performed over a carrying distan ce of 6 m, and carrying frequency of once and twice per minute and once eve ry 5 minutes. As in the case of manual lifting, the psychophysical approach was used to determine MAWC. Heart rate (HR) oxygen uptake (VO2) and catego ry-ratio ratings of perceived exertion (CRRPE) at the MAWC were also record ed. The results indicated that MAWC for two-handed tasks was significantly influenced by age for males-younger males carried 26% more weight than olde r males. Males, even though carrying less weight in two hands, were subject ed to higher physiological burden (elevated heart rate). Females performing two-handed carrying tasks, on the other hand, exhibited no age effect. MAW C for males and females for one-handed carrying tasks and bag carrying were nor affected either by age of frequency. None of the other responses (HR, VO2, and CRRPE) for one-handed carrying and bag-carrying tasks were effecte d by either age of frequency. Although not directly compared, MAWC for all three activities were different.