Category: International; Military and Veterans Affairs; Athlete Development & Sports Rehabilitation
To investigate the effect of a two hour 20.5 kg load carriage task on shoulder neuromuscular functions compared to unloaded walking. Also, to investigate groups needed recovery time. We hypothesized: that “load group” would show a decrement and longer recovery after 2 hours of walking compared to “no load group”.
Setting : Laboratory
Participants (or Animals, Specimens, Cadavers) :
A convenient sample of twenty-six healthy participants, divided into two equal groups. Ten females, 16 males, the mean and standard deviation for both groups(age 25±5.8years; weight 70±10.5kg; height 173±9.6cm). Subjects were excluded who had recent shoulder injuries, or previous medical and neurological problems.
Data were collected from the right shoulder at baseline, immediately post walking task and at subsequent intervals over the next 30 minutes recovery.
Main Outcome Measure(s) :
Dominant arm abduction strength and endurance, axillary nerve amplitude, and shooting accuracy, all assessed at baseline and sequentially post walking through recovery. Subjects walked for 2 hours on leveled treadmill carrying a 20.5kg backpack for “Load group” at a velocity of(5.5-7km/h). One-way repeated measures ANOVA followed by Bonferroni post-hoc analysis if significant difference exists.
Strength decreased in load group by 19%(p=0.005) and recovered at 30 minutes, with no change following no load walking(p=0.314). Endurance reduced in load group by 9%(p=0.05) and recovered after 10 minutes, with no change following no load walking(p=0.274). No significant change exists in nerve amplitude and accuracy. No significant difference between groups across all measures.
Walking with a heavy backpack for 2 hours reduced significantly shoulder strength. Carrying heavier loads and walking for longer periods, especially in a military population, will affect the performance and might increase the risk of injuries if recovery not allowed.
Muataz Almaddah– Ph.D Candidate, University of Kentucky, Lexington, Kentucky
Arthur Nitz– Proffesor, University of Kentucky, Lexington, Kentucky
John Abt– Associate Professor Director, Sports Medicine Research Institute, University of Kentucky, Lexington, Kentucky
Babak Bazrgari– Associate Professor, F. Joseph Halcomb III, M.D. Department of Biomedical Engineering,, University of Kentucky, Lexington, Kentucky
Tim Uhl– Director of Musculoskeletal Laboratory Professor, University of Kentucky, Lexington, Kentucky