The physiological cost of carrying loads in temperate and hot environments.
Hum Factors 1971 Apr; 13(2):153-161
Cartons weighing 10, 15 and 20 kg were carried by 3 pretrained subjects with the hands in front of the body at speeds of 4 and 5 kilometers per hour on the level and on 4 percent gradient at dry ambient temperatures of 20, 35 and 45 degrees centigrade; each test involved three 5-minute periods of load carrying, walking without load and sitting. At each speed, step rate increased with load- weight increase, although the increase (but not total cost) was less when carrying up hill. Metabolic cost per total weight of body and load also increased with load increase; thus work efficiency decreased. The metabolic cost for each kg of load carried was 1.3- 2.3 times greater than the cost per kg body weight without load. No significant differences in metabolic cost were observed under the 3 thermal conditions but heart rate increased 7-10 beats per minute for each 10 degrees centigrade air-temperature rise. It is concluded that physiologically, 15-kg packages are perferable to 10- and 20-kg packages when large amounts of material must be manhandled.
NIOSH-Publication; NIOSH-Grant; Physiological-effects; Heart-rate; High-temperature; Thermal-effects
Occupational Health Univ of Pittsburgh Sch of PH 130 DE Soto Street Pittsburgh, PA 15213
University of Pittsburgh, Pittsburgh, Pennsylvania