Ole Steen Mortensen

Muscle Activation and Perceived Loading During Rehabilitation Exercises: Comparison of Dumbbells and Elastic Resistance

Background High-intensity resistance training plays an essential role in the prevention and rehabilitation of musculoskeletal injuries and disorders. Although resistance exercises with heavy weights yield high levels of muscle activation, the efficacy of more user-friendly forms of exercise needs to be examined. Objective The aim of this study was to investigate muscle activation and perceived loading during upper-extremity resistance exercises with dumbbells compared with elastic tubing. Design A single-group, repeated-measures study design was used. Setting Exercise evaluation was conducted in a laboratory setting. Participants Sixteen female workers (aged 26–55 years) without serious musculoskeletal diseases and with a mean neck and shoulder pain intensity of 7.8 on a 100-mm visual analog scale participated in the study. Measurements Electromyographic (EMG) activity was measured in 5 selected muscles during the exercises of lateral raise, wrist extension, and shoulder external rotation during graded loadings with dumbbells (2–7.5 kg) and elastic tubing (Thera-Band, red to silver resistance). The order of exercises and loadings was randomized for each individual. Electromyographic amplitude was normalized to the absolute maximum EMG amplitude obtained during maximal voluntary isometric contraction and exercise testing. Immediately after each set of exercise, the Borg CR10 scale was used to rate perceived loading during the exercise. Results Resistance exercise with dumbbells as well as elastic tubing showed increasing EMG amplitude and perceived loading with increasing resistance. At the individually maximal level of resistance for each exercise—defined as the 3 repetitions maximum—normalized EMG activity of the prime muscles was not significantly different between dumbbells (59%–87%) and elastic tubing (64%–86%). Perceived loading was moderately to very strongly related to normalized EMG activity (r=.59–.92). Limitations The results of this study apply only for exercises performed in a controlled manner (ie, without sudden jerks or high acceleration). Conclusions Comparably high levels of muscle activation were obtained during resistance exercises with dumbbells and elastic tubing, indicating that therapists can choose either type in clinical practice. The Borg CR10 can be a useful aid in estimating intensity of individual rehabilitation protocols.

Effectiveness of small daily amounts of progressive resistance training for frequent neck/shoulder pain: Randomised controlled trial

&NA; Regular physical exercise is a cornerstone in rehabilitation programs, but adherence to comprehensive exercise remains low. This study determined the effectiveness of small daily amounts of progressive resistance training for relieving neck/shoulder pain in healthy adults with frequent symptoms; 174 women and 24 men working at least 30 h per week and with frequent neck/shoulder pain were randomly assigned to resistance training with elastic tubing for 2 or 12 minutes per day 5 times per week, or weekly information on general health (control group). Primary outcomes were changes in intensity of neck/shoulder pain (scale 0 to 10), examiner‐verified tenderness of the neck/shoulder muscles (total tenderness score of 0 to 32), and isometric muscle strength at 10 weeks. Compared with the control group, neck/shoulder pain and tenderness, respectively, decreased 1.4 points (95% confidence interval −2.0 to −0.7, p < 0.0001) and 4.2 points (95% confidence interval −5.7 to −2.7, p < 0.0001) in the 2‐minute group and 1.9 points (95% confidence interval −2.5 to −1.2, p < 0.0001) and 4.4 points (95% confidence interval −5.9 to −2.9, p < 0.0001) in the 12‐minute group. Compared with the control group, muscle strength increased 2.0 Nm (95% confidence interval 0.5 to 3.5 Nm, p = 0.01) in the 2‐minute group and 1.7 Nm (95% confidence interval 0.2 to 3.3 Nm, p = 0.02) in the 12‐minute group. In conclusion, as little as 2 minutes of daily progressive resistance training for 10 weeks results in clinically relevant reductions of pain and tenderness in healthy adults with frequent neck/shoulder symptoms. Trial registration: www.isrctn.org/ISRCTN60264809. In generally healthy adults with frequent neck/shoulder muscle pain, as little as 2 minutes of daily progressive resistance training reduces pain and tenderness.

Worksite interventions for preventing physical deterioration among employees in job-groups with high physical work demands: Background, design and conceptual model of FINALE

BackgroundA mismatch between individual physical capacities and physical work demands enhance the risk for musculoskeletal disorders, poor work ability and sickness absence, termed physical deterioration. However, effective intervention strategies for preventing physical deterioration in job groups with high physical demands remains to be established. This paper describes the background, design and conceptual model of the FINALE programme, a framework for health promoting interventions at 4 Danish job groups (i.e. cleaners, health-care workers, construction workers and industrial workers) characterized by high physical work demands, musculoskeletal disorders, poor work ability and sickness absence.Methods/DesignA novel approach of the FINALE programme is that the interventions, i.e. 3 randomized controlled trials (RCT) and 1 exploratory case-control study are tailored to the physical work demands, physical capacities and health profile of workers in each job-group. The RCT among cleaners, characterized by repetitive work tasks and musculoskeletal disorders, aims at making the cleaners less susceptible to musculoskeletal disorders by physical coordination training or cognitive behavioral theory based training (CBTr). Because health-care workers are reported to have high prevalence of overweight and heavy lifts, the aim of the RCT is long-term weight-loss by combined physical exercise training, CBTr and diet. Construction work, characterized by heavy lifting, pushing and pulling, the RCT aims at improving physical capacity and promoting musculoskeletal and cardiovascular health. At the industrial work-place characterized by repetitive work tasks, the intervention aims at reducing physical exertion and musculoskeletal disorders by combined physical exercise training, CBTr and participatory ergonomics. The overall aim of the FINALE programme is to improve the safety margin between individual resources (i.e. physical capacities, and cognitive and behavioral skills) and physical work demands, and thereby reduce the physical deterioration in a long term perspective by interventions tailored for each respective job-group.DiscussionThe FINALE programme has the potential to provide evidence-based knowledge of significant importance for public health policy and health promotion strategies for employees at high risk for physical deterioration.Trial registrationsISRCTN96241850, NCT01015716 and NCT01007669

Implementation of neck/shoulder exercises for pain relief among industrial workers: a randomized controlled trial.

BackgroundAlthough leisure-time physical activity is important for health, adherence to regular exercise is challenging for many adults. The workplace may provide an optimal setting to reach a large proportion of the adult population needing regular physical exercise. This study evaluates the effect of implementing strength training at the workplace on non-specific neck and shoulder pain among industrial workers.MethodsCluster-randomized controlled trial involving 537 adults from occupations with high prevalence of neck and shoulder pain (industrial production units). Participants were randomized to 20 weeks of high-intensity strength training for the neck and shoulders three times a week (n = 282) or a control group receiving advice to stay physically active (n = 255). The strength training program followed principles of progressive overload and periodization. The primary outcome was changes in self-reported neck and shoulder pain intensity (scale 0-9).Results85% of the participants followed the strength training program on a weekly basis. In the training group compared with the control group, neck pain intensity decreased significantly (-0.6, 95% CI -1.0 to -0.1) and shoulder pain intensity tended to decrease (-0.2, 95% CI -0.5 to 0.1, P = 0.07). For pain-cases at baseline (pain intensity > = 3) the odds ratio - in the training group compared with the control group - for being a non-case at follow-up (pain intensity < 3) was 2.0 (95% CI 1.0 to 4.2) for the neck and 3.9 (95% CI 1.7 to 9.4) for the shoulders.ConclusionHigh-intensity strength training relying on principles of progressive overload can be successfully implemented at industrial workplaces, and results in significant reductions of neck and shoulder pain.Trial registrationNCT01071980.

A prospective cohort study on severe pain as a risk factor for long-term sickness absence in blue- and white-collar workers

Objective To estimate the impact of pain in different body regions on future long-term sickness absence (LTSA) among blue- and white-collar workers. Method Prospective cohort study in a representative sample of 5603 employees (the Danish Work Environment Cohort Study) interviewed in 2000, and followed in 2001–2002 in a national sickness absence register. Cox regression analysis was performed to assess the risk estimates of mutually adjusted severe pain in the neck/shoulder, low back, hand/wrist and knees for onset of LTSA, defined as receiving sickness absence compensation for at least 3 consecutive weeks. Age, gender, body mass index, smoking and diagnosed disease were controlled for. Results In 2000 the prevalence among blue- and white-collar workers, respectively, of severe pain was 33% and 29% (neck/shoulder), 33% and 25% (low back), 16% and 11% (hand/wrists), and 16% and 12% (knees). During 2001–2002, the prevalence of LTSA among blue- and white-collar workers was 18% and 12%, respectively. Hand/wrist pain (HR 1.49, 95% CI 1.23 to 1.81) and low back pain (HR 1.30, 95% CI 1.11 to 1.53) were significant risk factors among the total cohort. Neck/shoulder pain was a significant risk factor among white-collar workers only (HR 1.35, 95% CI 1.21 to 1.85). Knee pain was not a significant risk factor. Conclusion While hand/wrist pain and low back pain are general risk factors for LTSA, neck/shoulder pain is a specific risk factor among white-collar workers. This study suggests the potential for preventing future LTSA through interventions to manage or reduce musculoskeletal pain.

Kettlebell training for musculoskeletal and cardiovascular health: a randomized controlled trial

OBJECTIVE The aim of this trial was to investigate the effectiveness of a worksite intervention using kettlebell training to improve musculoskeletal and cardiovascular health. METHODS This single-blind randomized controlled trial involved 40 adults from occupations with a high prevalence of reported musculoskeletal pain symptoms (mean age 44 years, body mass index 23 kg/m², 85% women, with pain intensity of the neck/shoulders 3.5 and of the low back 2.8 on a scale of 0-10). A blinded assessor took measures at baseline and follow-up. Participants were randomly assigned to training--consisting of ballistic full-body kettlebell exercise 3 times per week for 8 weeks--or a control group. The main outcome measures were pain intensity of the neck/shoulders and low back, isometric muscle strength, and aerobic fitness. RESULTS Compared with the control group, pain intensity of the neck/shoulders decreased 2.1 points [95% confidence interval (95% CI) -3.7- -0.4] and pain intensity of the low back decreased 1.4 points (95% CI -2.7- -0.02) in the training group. Compared with the control group, the training group increased muscle strength of the trunk extensors (P<0.001), but not of the trunk flexors and shoulders. Aerobic fitness remained unchanged. CONCLUSIONS Worksite intervention using kettlebell training reduces pain in the neck/shoulders and low back and improves muscle strength of the low back among adults from occupations with a high prevalence of reported musculoskeletal pain symptoms. This type of training does not appear to improve aerobic fitness.

Occupational and leisure time physical activity: risk of all-cause mortality and myocardial infarction in the Copenhagen City Heart Study. A prospective cohort study

Objectives Men with low physical fitness and high occupational physical activity are recently shown to have an increased risk of cardiovascular disease and all-cause mortality. The association between occupational physical activity with cardiovascular disease and all-cause mortality may also depend on leisure time physical activity. Design A prospective cohort study. Setting The Copenhagen City Heart Study. Participants 7819 men and women aged 25–66 years without a history of cardiovascular disease who attended an initial examination in the Copenhagen City Heart Study in 1976–1978. Outcome measures Myocardial infarction and all-cause mortality. Occupational physical activity was defined by combining information from baseline (1976–1978) with reassessment in 1981–1983. Conventional risk factors were controlled for in Cox analyses. Results During the follow-up from 1976 to 1978 until 2010, 2888 subjects died of all-cause mortality and 787 had a first event of myocardial infarction. Overall, occupational physical activity predicted all-cause mortality and myocardial infarction in men but not in women (test for interaction p=0.02). High occupational physical activity was associated with an increased risk of all-cause mortality among men with low (HR 1.56; 95% CI 1.11 to 2.18) and moderate (HR 1.31; 95% CI 1.05 to 1.63) leisure time physical activity but not among men with high leisure time physical activity (HR 1.00; 95% CI 0.78 to 1.26) (test for interaction p=0.04). Similar but weaker tendencies were found for myocardial infarction. Among women, occupational physical activity was not associated with subsequent all-cause mortality or myocardial infarction. Conclusions The findings suggest that high occupational physical activity imposes harmful effects particularly among men with low levels of leisure time physical activity.

Influence of frequency and duration of strength training for effective management of neck and shoulder pain: a randomised controlled trial

Background Specific strength training can reduce neck and shoulder pain in office workers, but the optimal combination of exercise frequency and duration remains unknown. This study investigates how one weekly hour of strength training for the neck and shoulder muscles is most effectively distributed. Methods A total of 447 office workers with and without neck and/or shoulder pain were randomly allocated at the cluster-level to one of four groups; 1×60 (1WS), 3×20 (3WS) or 9×7 (9WS) min a week of supervised high-intensity strength training for 20 weeks, or to a reference group without training (REF). Primary outcome was self-reported neck and shoulder pain (scale 0–9) and secondary outcome work disability (Disability in Arms, Shoulders and Hands (DASH)). Results The intention-to-treat analysis showed reduced neck and right shoulder pain in the training groups after 20 weeks compared with REF. Among those with pain ≥3 at baseline (n=256), all three training groups achieved significant reduction in neck pain compared with REF (p<0.01). From a baseline pain rating of 3.2 (SD 2.3) in the neck among neck cases, 1WS experienced a reduction of 1.14 (95% CI 0.17 to 2.10), 3WS 1.88 (0.90 to 2.87) and 9WS 1.35 (0.24 to 2.46) which is considered clinically significant. DASH was reduced in 1WS and 3WS only. Conclusion One hour of specific strength training effectively reduced neck and shoulder pain in office workers. Although the three contrasting training groups showed no statistical differences in neck pain reduction, only 1WS and 3WS reduced DASH. This study suggests some flexibility regarding time-wise distribution when implementing specific strength training at the workplace.

Patients’ perceptions of informed consent in acute myocardial infarction research: a questionnaire based survey of the consent process in the DANAMI-2 trial

Objective: To analyse how patients in the acute phase of a myocardial infarct experience the informed consent procedure of a clinical trial. Design: A questionnaire based follow up survey including patients who gave informed consent as well as patients who did not consent to the trial. Patients: 103 patients who gave informed consent and 78 who did not consent to the second Danish acute myocardial infarction trial (DANAMI-2). Results: 76% of the trial participants and 63% of the non-participants agreed or mostly agreed that they felt able to make a decision about whether or not to participate in the trial; 50% of the trial participants and 34% of the non-participants found it acceptable that patients in their situation have to make such a decision. Only 28% of the trial participants and 7% of the non-participants read the information sheet before they made the decision. Conclusions: Informed consent should be sought in acute myocardial infarction trials despite the emergency situation and the medical condition of the patients. Patients’ self assessed ability to make a decision should be explicitly addressed during the informed consent process and patients should not be pressurised into decision making. Physicians and research ethics committees should focus specifically on improving the oral information.

Long work hours and physical fitness: 30-year risk of ischaemic heart disease and all-cause mortality among middle-aged Caucasian men

Background No previous long-term studies have examined if workers with low physical fitness have an increased risk of cardiovascular mortality due to long work hours. The aim of this study was to test this hypothesis. Methods The study comprised 30-year follow-up of a cohort of 5249 gainfully employed men aged 40–59 years in the Copenhagen Male Study. 274 men with cardiovascular disease were excluded from the follow-up. Physical fitness (maximal oxygen consumption, Vo2max) was estimated using the Åstrand bicycle ergometer test, and number of work hours was obtained from questionnaire items; 4943 men were eligible for the incidence study. Results 587 men (11.9%) died because of ischaemic heart disease (IHD). Cox analyses adjusted for age, blood pressure, smoking, alcohol, body mass index, diabetes, hypertension, physical work demands, and social class, showed that working more than 45 h/week was associated with an increased risk of IHD mortality in the least fit (Vo2max range 15–26; HR 2.28, 95% CI 1.10 to 4.73), but not intermediate (Vo2max range 27–38; HR 0.94, 95% CI 0.59 to 1.51) and most fit men (Vo2max range 39–78; HR 0.91, 95% CI 0.41 to 2.02) referencing men working less than 40 h/week. Conclusions The findings indicate that men with low physical fitness are at increased risk for IHD mortality from working long hours. Men working long hours should be physically fit.