Strength Training Improves Fatigue Resistance and Self-Rated Health in Workers with Chronic Pain: A Randomized Controlled Trial.
Chronic musculoskeletal pain is widespread in the working population and leads to muscular fatigue, reduced work capacity, and fear of movement. While ergonomic intervention is the traditional approach to the problem, physical exercise may be an alternative strategy. This secondary analysis of a randomized controlled trial investigates the effect of strength training on muscular fatigue resistance and self-rated health among workers with chronic pain. Sixty-six slaughterhouse workers with chronic upper limb pain and work disability were randomly allocated to 10 weeks of strength training or usual care ergonomic training (control). At baseline and follow-up, participants performed a handgrip muscular fatigue test (time above 50% of maximal voluntary contraction force) with simultaneous recording of electromyography. Additionally, participants replied to a questionnaire regarding self-rated health and pain. Time to fatigue, muscle strength, hand/wrist pain, and self-rated health improved significantly more following strength training than usual care (allP< 0.05). Time to fatigue increased by 97% following strength training and this change was correlated to the reduction in fear avoidance (Spearman's rho = -0.40;P= 0.01). In conclusion, specific strength training improves muscular fatigue resistance and self-rated health and reduces pain of the hand/wrist in manual workers with chronic upper limb pain. This trial is registered with ClinicalTrials.gov NCT01671267.
National Research Centre for the Working Environment, Copenhagen, Denmark; Department of Sports Science and Clinical Biomechanics, SDU Muscle Research Cluster, University of Southern Denmark, Odense, Denmark.
Emil
0000-0001-7408-222X
E
Sundstrup
National Research Centre for the Working Environment, Copenhagen, Denmark; Department of Sports Science and Clinical Biomechanics, SDU Muscle Research Cluster, University of Southern Denmark, Odense, Denmark.
Markus Due
MD
Jakobsen
National Research Centre for the Working Environment, Copenhagen, Denmark; Physical Activity and Human Performance Group, SMI, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark.
Mikkel
0000-0002-1415-3097
M
Brandt
National Research Centre for the Working Environment, Copenhagen, Denmark; The Carrick Institute, Clinical Neuroscience and Rehabilitation, Cape Canaveral, FL 32920, USA.
Kenneth
K
Jay
Department of Sports Science and Clinical Biomechanics, SDU Muscle Research Cluster, University of Southern Denmark, Odense, Denmark.
Per
0000-0002-9773-7361
P
Aagaard
National Research Centre for the Working Environment, Copenhagen, Denmark; Physical Activity and Human Performance Group, SMI, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark.
Lars Louis
0000-0003-2777-8085
LL
Andersen
D000003:Abattoirs; D000328:Adult; D018771:Arthralgia / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D059350:Chronic Pain / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D059026:Diagnostic Self Evaluation; D005081:Exercise Therapy / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018763:Muscle Fatigue; D009784:Occupational Diseases / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000517:prevention & control*; D010147:Pain Measurement; D064797:Physical Conditioning, Human / Q000379:methods; D057566:Self Report; D016037:Single-Blind Method; D016896:Treatment Outcome