J. Lo, G. N. McCabe, K. M. DeGoede, H. Okuizumi and J. A. Ashton-Miller
From the Department of Biomedical Engineering, Biomechanics Research Laboratory, University of Michigan, Ann Arbor
To test the working hypotheses that after a brief (10 min) intervention, (a) young adults can volitionally reduce fall-related wrist impact forces, and (b) no difference in impact force would exist between intervention and control groups at 3-weeks or 3-months follow-up.
The wrist is the most commonly fractured site in the body at any age, most often as a result of impact with the ground while arresting a forward fall.
Twenty-nine healthy young male volunteers participated. A 3-month intervention group (n = 10) performed five standardized forward falls before and after a 10-min instructional intervention aimed at reducing wrist impact forces during the baseline visit. They, along with a 3-month control group (n = 11) who did not receive the intervention, were remeasured in five trials at 3-weeks and 3-months follow-up, without intervening practice. A baseline control group (n = 8) performed the five trials, then repeated them at the baseline visit without receiving the intervention. Unilateral body segment kinematics and bilateral hand-ground impact forces were measured and the hypotheses were tested using repeated measures analysis of variance.
At the baseline visit, a significant group-by-trial-block interaction was found (P = 0.02): the 3-month intervention group reduced their average maximum impact forces by 18% from initial values (P = 0.002); the baseline control group did not do so (0.5% increase, P = 0.91). The 3-month intervention (20 falls) and control (15 falls) groups did not differ at the 3-month follow-up (P = 0.62); however, when the groups were combined their maximum impact force had decreased significantly (8.9%, P = 0.04) over that time.
Healthy young males learned in 10 min to significantly reduce wrist impact forces in forward falls, but retention was poor at 3-weeks follow-up. Irrespective of group, however, after the 5 falls at 3-weeks subjects had taught themselves to reduce their impact forces at the 3-months follow-up.
A brief educational intervention can significantly reduce forward fall-related impact forces in the short term. However, with or without the brief intervention, the experience of performing between 5–10 forward falls 3 weeks apart apparently resulted in decreased impact forces over the next 2 months, thereby reducing the risk of injury in these forward falls.