Cardiovascular and Psychophysical Response to Repetitive Lifting Tasks in Women.

Abstract

Background: Understanding the cardiovascular and psychophysical demands of repetitive lifting tasks is important in job design strategies. This study determined the cardiovascular (oxygen consumption (VO₂) and heart rate (HR) and psychophysical response to repetitive lifting tasks in women.

Methods: Ten female (age 27 ± 5 yrs) participants transferred 11.4, 15.9, and 20.5 kg weights back and forth from a rung 40.6 cm high to a rung 156.2 cm high. Rungs were 195.6 cm apart horizontally. Three, 10 minute bouts (1 = 11.4 kg; 2 = 15.9 kg; 3 = 20.5 kg) were performed at 6 lifts per minute. Cardiovascular and psychophysical (rating of perceived exertion, RPE) parameters were monitored throughout the bouts. VO₂max and HRmax were determined via a maximal treadmill test.

Results: VO₂, HR, and RPE were significantly different between each work bout (p < 0.01), with each outcome variable increasing as load increased. VO₂max and HRmax equaled 46.5 ± 7.5 mL·kg^-1·min^-1 and 191 ± 11 bpm, respectively. Work at 11.4 kg was performed at 38% VO₂max and 63% HRmax; at 15.9 kg at 41% VO₂max and 72% HRmax; and at 20.5 kg at 49% VO₂max and 81% HRmax. RPE at 11.4, 15.9, and 20.5 kgs were: 8.4 ± 1.6, 11.4 ± 1.9, and 15.0 ± 2.2.

Conclusion: During these repetitive lifting tasks, metabolic cost and perceived exertion increased with weight lifted; average work intensity ranged from 63 to 81% of HRmax and 38 to 49% of VO₂max. Results have important implications in relation to job pacing and design, and worksite health promotion strategies aimed at reducing work place injury.