The Science Journal of the American Association for Respiratory Care

2003 OPEN FORUM Abstracts

Gender differences in cardiorespiratory responses during standardized arm cranking and task-specific pushing-pulling

Rammohan V. Maikala PhD1, Yagesh N. Bhambhani PhD2

1 Research Scientist, Liberty Mutual Research Institute for Safety, Hopkinton, MA 01748, USA, email: rammohan.maikala@libertymutual.com, FAX: 508-435-0482

2 Professor, Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, T6G 2P6, CANADA


Background:
Occupational fitness evaluation often includes testing for worker's physical capacity using standardized ergometric protocols. However, applicability of protocol results obtained from these methods to worker's physical capacity to perform specific jobs is questionable. The purpose of this study was to compare the whole-body cardiorespiratory responses between standardized arm cranking and task-specific pushing-pulling tests in 11 healthy men and 11 healthy women.

Methods:
Each subject randomly completed: incremental arm cranking (in a seated posture); and pushing-pulling (in a standing posture) to voluntary fatigue, in a random order, on two separate days. The test protocol included a two-minute baseline, two-minute warm up at no load, followed by specific load increments (25 Watts - Arm Cranking; 30 lb-in torque - Pushing-Pulling) every two minutes till exhaustion. These protocols were ended with a two-minute active and a four-minute passive recovery period. Cardiorespiratory responses were monitored using an automated metabolic cart and a remote heart rate monitor.

RESULTS:
A two-way analysis of variance showed that peak cardiorespiratory responses: absolute and relative oxygen uptake, oxygen pulse, respiratory exchange ratio, ventilation rate, and respiratory frequency were significantly higher during arm cranking compared to pushing-pulling (P<0.05). However, peak heart rate and ventilatory equivalent ratio for oxygen were similar between these exercise modes (P>0.05). Power output during arm cranking was significantly higher (by 79%) than pushing-pulling (P<0.01), with men demonstrating 30% greater power output during both exercise modes (P<0.01) than women. The lower power output generated during pushing-pulling resulted in significantly greater ratios of peak oxygen uptake to peak power output (by 72%) compared to arm cranking (P<0.05). In general, men showed greater cardiorespiratory responses (absolute oxygen uptake, oxygen pulse, ventilation rate, tidal volume) than women (P<0.05). However, gender did not influence the relative oxygen consumption, heart rate, respiratory frequency, ventilatory equivalent for oxygen, respiratory exchange ratio, and ratios of absolute and relative oxygen uptake to power output during both modes of exercise (P>0.05).

CONCLUSION:
These results indicated that pushing-pulling is metabolically less efficient than arm cranking. Biomechanical differences in the postures adopted during these exercise modes might be the primary reason for such physiological differences. These physiological differences highlight the importance of using task-specific protocols in occupational fitness programs.

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