Physiological responses during and after intermittent sorting of postal parcels

Abstract

Physiological responses including ventilatory gas exchange, blood lactate (LA) and heart rate (HR) were studied during and after intermittent manual sorting of postal parcels in a simulated workplace constructed in the laboratory. Responses to parcel sorting were compared to those obtained during arm crank and cycle exercise. The subjects were 21 healthy male sorters. Their age was 33 * 6 years and weight 78.3 f 12.7 kg. The subjects' maximal oxygen consumption (VO, max) was 2-52 f 0.32 I min ' for arm cranking, and 3.24+_044 1 min -' for cycling. The subjects sorted parcels with a mean weight of 5.1 kg from a container onto two trollies for 3.5 min at each of the following work rates: slow (3 + 0 parcels mine I), habitual (8-6 f 2.4 parcels min-I), accelerated (10-8 + 3.1 parcels min-I), and maximal (16.9f 7-6 parcelsmin-I). The tasks were separated by rest periods of 30 s for venous blood sampling, and the recovery was followed for 16 min. At the habitual work rate, P O 2 was 1-36 f 0.38 1 min-', LA 1-8 f 0.9 mmol 1-', and HR 105 & 22 beats min ' . The parcel sorting studied was predominantly aerobic (LA < 4-0 mmol 1 -') up to the work rate of about 20 parcels min-I . After the recovery period, breathing frequency and HR remained significantly higher than at rest. The physiological responses to parcel sorting substantially differed from those to arm cranking, whereas they were almost equal to cycling.

Breathing patterns and heart rate during simulated occupational upper limb tasks in normal subjects

“…In fact, given the greater workload of unsupported work, V T should theoretically have been greater during this condition than during supported arm work. The finding that ventilation increases as a result of an elevation in respiratory rate but not V T during arm activity has been verified by other studies (Celli et al, 1988;Louhevaara et al, 1988;Strom, 1992).…”

“…Previous research has extensively investigated such work tasks in relation to musculoskeletal disorders of the neck, back and upper limb (Troup, 1984;Hagberg & Kilbom, 1992, Hagberg et al, 1995. Physiological responses during heavy lifting and carrying work are also well established (Petrovsky & Lind 1978a, 1978bPeacock, 1980;Louhevaara et al, 1988;Snook & Circello, 1991). However, the physiological effects of repetitive light manual work have not been thoroughly researched (Strasser & Ernst, 1992), even though such tasks may also be harmful to the worker.…”

“…The inability to perform relatively simple tasks involving the arms because of dyspnoea is apparently disproportionate to the metabolic demands of the tasks . Little is known about the effect these work tasks have on the pattern of breathing and respiratory muscle activation or whether the static work of the upper body in unsupported material handling tasks restricts breathing and disturbs gas exchange (Louhevaara et al, 1988).…”

“…Additionally, much of the ventilatory response exercise literature is concerned with maximal exercise which may not represent the responses during submaximal occupational tasks. There is also a lack of information on recovery breathing patterns following cessation of work, yet the recovery period is important when determining the optimum level of occupational physical stress and work-rest regimes for tasks with varying muscular demands (Louhevaara et al, 1988).…”

Physical Capacity of Occupationally Active Population and Capability to Perform Physical Work

“…Oxygen consumption during maximal effort, the load of the cardiovascular system and the subjective feeling related to effort depend on the mass of the muscles involved [27,28,29]. Effort, which can be low when large groups of muscles are involved, can be very high when it involves small muscles.…”