Back muscle response to sudden trunk loading can be modified by training among healthcare workers.
METHODS
Experimental study of the effect of physical training on the reaction to sudden back loading.


OBJECTIVE
To investigate the effect and sustainability of "on the job training" on the reaction to sudden back loading among employees at a geriatric ward.


BACKGROUND
Available data suggest that a delayed muscle reflex response to sudden trunk loading may increase the risk of low back injuries. We have previously shown that training may alter the response to sudden trunk loading in healthy subjects and decrease the time elapsed until stopping of the forward movement of the trunk (stopping time). Data on the possibilities of a training-induced improvement in the reflex response among workers exposed to sudden trunk loading on the job are, however, nonexistent, and there is no evidence of long-term benefits, i.e., the sustainability of a positive training effect.


METHODS
The study included 23 participants and 14 controls. All were healthy without prior history of low back pain (LBP). The training group participated in a total of 18 training sessions during a 9-week period. The training focused on reactions to a variety of sudden trunk loadings. Before and after the training intervention and at a 1-year follow-up, all subjects were tested for their reaction to expected and unexpected sudden trunk loading by applying a horizontal force of 58 N to the upper back of the subjects and measuring the electromyographic (EMG) response from the erector spinae muscles.


RESULTS
In the training group, the stopping time and the distance moved after unexpected sudden trunk loading decreased significantly (13%-19%, P = 0.02). The improved stopping time was associated with marked changes in the time-wise distribution of the EMG signal after training. In addition, the follow-up study showed a high sustainability of the training effect.


CONCLUSIONS
The results demonstrated a training-induced improvement of the response to sudden trunk loading that may be beneficial in workers, such as nurses, who are exposed to sudden trunk perturbations during patient handling.
Pedersen
Mogens Theisen
MT
Institute of Exercise and Sport Sciences, University of Copenhagen, Denmark. mtpedersen@ifi.ku.dk
Essendrop
Morten
M
Skotte
Jørgen H
JH
Jørgensen
Kurt
K
Schibye
Bente
B
Fallentin
Nils
N
D000328:Adult; D001415:Back / Q000502:physiology*; D001416:Back Pain / Q000503:physiopathology / Q000517:prevention & control*; D004576:Electromyography; D005260:Female; D005851:Geriatric Nursing / Q000193:education*; D006801:Humans; D007318:Inservice Training / Q000379:methods*; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000502:physiology; D009740:Nursing Staff / Q000193:education; D009784:Occupational Diseases / Q000503:physiopathology / Q000517:prevention & control*; D010806:Physical Education and Training; D016474:Weight-Bearing