Maximal manual stretcher carriage: performance and recovery of male and female ambulance workers

• Published in: Ergonomics Vol. 50; no. 5; pp. 752 - 762
• Main Authors: Leyk, D., Rohde, U., Erley, O., Gorges, W., Essfeld, D., Erren, T. C., Piekarski, C.
• Format: Journal Article
• Language: English
• Published: London Taylor & Francis 01.05.2007; Washington, DC Taylor & Francis LLC
• Subjects: Adaptation, Physiological; Adolescent; Adult; Ambulance services; Ambulances; Applied physiology; Biological and medical sciences; Biomechanical Phenomena; Eccentric strain; Effects; Emergency Medical Technicians; Ergonomics. Work place. Occupational physiology; Exercise; Exercise Test; Fatigue; Fatigue - physiopathology; Female; Gender; Hand Strength - physiology; Hand-grip strength; Heart rate; Heart Rate - physiology; Human physiology applied to population studies and life conditions. Human ecophysiology; Humans; Load carriage; Male; Manual coordination; Medical sciences; Middle Aged; Military Personnel; Space life sciences; Time; Weight-Bearing - physiology; Human; Eccentric strain; Manual coordination; Ergonomics; Physical performance; Hand-grip strength; Fatigue; Worker; Hand; Recovery; Load carriage
• ISSN: 0014-0139; 1366-5847
• DOI: 10.1080/00140130701195063

The effects of a maximal duration stretcher carriage on heart rate (HR), lactate concentration, hand steadiness and hand-grip strength were studied up to 72 h post-exercise in 17 male and 15 female military ambulance personnel. Using both hands for transport, the participants walked on a treadmill ergometer at a speed of 4.5 km/h. Force measurements at the handlebars yielded mean loads of 245 N (25 kg) on each side. Each step on the treadmill induced additional force oscillations with peak forces up to 470 N corresponding to 130% (women) and 98% (men) of maximal voluntary contraction (MVC). In the males the maximal transport time was about twice the time in women (mean ± SD: 184 ± 51 s vs. 98 ± 34 s). These differences had no significant effect on HR and lactate values. The same applies to hand steadiness, which showed only a transient deterioration immediately after exercise. In contrast to these parameters, substantial differences were seen in hand-grip strength recovery. Immediately after exercise, maximal hand-grip strength decreased by 150 N (25% MVC) in the males vs. 50 N (14%) in the females. Irrespective of gender, individuals with larger hand-grip strength and longer carriage durations (range 120 s-280 s) showed the slowest strength recoveries (up to 72 h) as compared to 1 h of recovery in participants with short transport durations (range 27 s-120 s). These findings suggest that the increasing number of eccentric strains during uninterrupted stretcher carriage induces cumulative muscle damages that may require some days for complete recovery.