Björn O. Äng

Graded Exercise for Recurrent Low-Back Pain : A Randomized, Controlled Trial With 6-, 12-, and 36-Month Follow-ups

Study Design. The study was a randomized controlled trial. Treatment was for 8 weeks, with follow-up posttreatment and at 6-, 12-, and 36- months. Objective. The purpose was to evaluate the effect of a graded exercise intervention emphasizing stabilizing exercises in patients with nonspecific, recurrent low back pain (LBP). Summary of Background Data. Exercise therapy is recommended and widely used as treatment for LBP. Although stabilizing exercises are reportedly effective in the management of certain subgroups of LBP, such intervention protocols have not yet been evaluated in relation to a more general exercise regimen in patients with recurrent LBP, all at work. Methods. Seventy-one patients recruited consecutively (36 men, 35 women) with recurrent nonspecific LBP seeking care at an outpatient physiotherapy clinic were randomized into 2 treatment groups; graded exercise intervention or daily walks. The primary outcome was perceived disability and pain at 12-month follow-up. Secondary outcomes included physical health, fear-avoidance, and self-efficacy beliefs. Results. Of the participants, 83% provided data at the 12-month follow-up and 79% at 36 months. At 12 months, between-group comparison showed a reduction in perceived disability in favor of the exercise group, whereas such an effect for pain emerged only immediately postintervention. Ratings of physical health and self-efficacy beliefs also improved in the exercise group over the long term, though no changes were observed for fear-avoidance beliefs. Conclusion. A graded exercise intervention, emphasizing stabilizing exercises, for patients with recurrent LBP still at work seems more effective in improving disability and health parameters than daily walks do. However, no such positive results emerged for improvement regarding pain over a longer term, or for fear-avoidance beliefs.

Predictive factors for 12-month outcome after anterior cruciate ligament reconstruction

There is a lack of knowledge regarding predictive factors for a successful clinical outcome after an anterior cruciate ligament (ACL) reconstruction. The aim was to investigate pre‐operative factors that may predict good outcomes as measured with the subscales Function in sports and recreation and Quality of life in Knee injury Osteoarthrithis Outcome Score (QOL‐KOOS), one‐leg hop test and Tegner Activity Scale 12 months after ACL reconstruction. Sixty‐four patients, operated with either patellar or hamstring tendon graft, were included. Demographics, range of motion, anterior knee laxity, pivot shift, muscle‐torques, anterior knee pain (AKP) and knee function were registered pre‐operatively and used in a multiple regression model. Results show less degree of AKP and low influence on knee function to be the most important predictors for good outcome in Sport/Rec‐KOOS (explained 31% of variances). Less AKP was in addition the most important predictor for QOL‐KOOS (14%). Patellar‐tendon graft, in favor of hamstring tendon graft, explained 8% of the improvement in the Tegner Activity Scale. In conclusion, a low degree of AKP was found to be the most important predictor for good clinical outcome 12 months after ACL reconstruction. Future studies, including psychological parameters, should use analyses that have the potential to control for independency between variables.

Effects of eccentric training on hand strength in subjects with lateral epicondylalgia: a randomized‐controlled trial

The main aim of this study was to evaluate the short‐term effects of daily eccentric exercises on functional pain‐free hand strength in subjects with long‐term lateral epicondylalgia. Forty‐two subjects with lateral epicondylalgia were randomly assigned either to a 6‐week home exercise regimen receiving eccentric training for their wrist extensors and a forearm band or to a control group receiving a forearm band only. The main outcomes were pain‐free hand‐grip and wrist‐extensor strength at mid‐ and end‐intervention follow‐ups, 3 and 6 weeks after inclusion, respectively. Secondary outcomes were a change in the proportion of cases with epicondylalgia and ratings of perceived pain (VAS) at follow‐up. Thirty‐seven (88%) subjects completed both the mid‐ and the end‐intervention follow‐up. Exercise members had significantly higher pain‐free hand‐grip (P=0.025) and wrist‐extensor strength (P<0.001) at the end of follow‐up, although there was no such effect at mid‐intervention. Regression analysis showed a reduction in the proportion of cases in the exercise group at the end of follow‐up (P=0.035). However, no between‐groups effect emerged for perceived pain. These data suggest that the daily home eccentric exercise regimen is effective in increasing functional pain‐free grip strength and reducing cases suffering from lateral epicondylalgia. However, no effect emerged for global perceived pain during the last week.

Neck/shoulder exercise for neck pain in air force helicopter pilots: a randomized controlled trial.

Study Design. The study was a randomized, controlled trial with blinded outcome assessment. A 6-week intervention was followed up directly afterwards and after 12 months. Objective. The purpose was to evaluate the preventive efficacy of a neck/shoulder exercise regimen for neck pain in air force helicopter pilots. Summary of Background Data. Neck pain is a significant medical problem in modern military aviation. Research shows neck-muscle dysfunction in subjects with various neck disorders. So far, evidence for neck exercise as prevention or early intervention is sparse, and few trials use randomized controlled design. Methods. Sixty-eight helicopter pilots on active flying duty with or without neck pain were randomly assigned to a supervised neck/shoulder exercise regimen or a control group receiving no such regimen. The key outcome was change in the prevalence of neck pain cases at the 12-month follow-up, rated for the previous week and the previous 3 months. Secondary outcomes included neck-flexor surface electromyographic activity during active craniocervical flexion and pain-related fear regarding physical activity. In addition, a secondary regression analysis included preintervention predictors that may be associated with change in prevalence of neck-pain cases at the 12-month follow-up. Results. Eighty-two percent (56/68) of the participants assigned at random completed the intervention and provided data at month 12. Regression analysis showed a reduction in the prevalence of neck pain cases in the exercise group, which was significant for pain ratings during the previous week, OR = 3.2 (95% CI = 1.3–7.8), and previous 3months, OR = 1.9 (95% CI = 1.2–3.2). Electromyographic activity at the highest contraction level was significantly reduced in the exercise group, P < 0.05, whereas no between-groups effect emerged for pain-related fear. Results from the secondary analysis showed that general strength training for more than 1 hour per week before the intervention predicted reduction in prevalence of pain at follow-up. Conclusion. A supervised neck/shoulder exercise regimen was effective in reducing neck pain cases in air force helicopter pilots. This was supported by improvement in neck-flexor function postintervention in regimen members. However, no effect emerged for pain-related fear. General strength training before the intervention predicted reduction in prevalence of pain at follow-up.

Is active sitting as active as we think

The aim of this study was to compare the biomechanical characteristics of sitting on a stool without a backrest (so as to encourage active sitting), sitting on a conventional office chair and standing in healthy participants. Thirteen healthy participants performed a keyboard-writing task during four (stable and unstable) sitting conditions and standing. Body segment positions and posture, postural sway and muscle activity of neck and trunk muscles were assessed with a motion capture system, a force plate and surface electromyography. The results showed that body segment positions, postural sway and trunk muscle activity were relatively similar for the stools without backrests compared with standing. All sitting conditions showed lower vertical upper body alignment, less anterior pelvic tilt and larger hip angles, compared with standing (p = 0.000). Unexpectedly, the muscle activity levels and total postural sway, sway velocity and sway in M/L and A/P directions were lower (p = 0.000) for the conditions that encouraged active sitting and standing, compared with the conventional office chair conditions. Practitioner Summary: Thirteen healthy participants performed a keyboard-writing task during different sitting conditions and standing and were analysed regarding posture, postural sway and trunk muscle activity. Surprisingly, less postural sway and less muscle activity were observed during the conditions that encourage active sitting, compared with sitting on a conventional office chair.

Inter- and intra-observer reliability of clinical movement-control tests for marines

BackgroundMusculoskeletal disorders particularly in the back and lower extremities are common among marines. Here, movement-control tests are considered clinically useful for screening and follow-up evaluation. However, few studies have addressed the reliability of clinical tests, and no such published data exists for marines. The present aim was therefore to determine the inter- and intra-observer reliability of clinically convenient tests emphasizing movement control of the back and hip among marines. A secondary aim was to investigate the sensitivity and specificity of these clinical tests for discriminating musculoskeletal pain disorders in this group of military personnel.MethodsThis inter- and intra-observer reliability study used a test-retest approach with six standardized clinical tests focusing on movement control for back and hip. Thirty-three marines (age 28.7 yrs, SD 5.9) on active duty volunteered and were recruited. They followed an in-vivo observation test procedure that covered both low- and high-load (threshold) tasks relevant for marines on operational duty. Two independent observers simultaneously rated performance as “correct” or “incorrect” following a standardized assessment protocol. Re-testing followed 7–10 days thereafter. Reliability was analysed using kappa (κ) coefficients, while discriminative power of the best-fitting tests for back- and lower-extremity pain was assessed using a multiple-variable regression model.ResultsInter-observer reliability for the six tests was moderate to almost perfect with κ-coefficients ranging between 0.56-0.95. Three tests reached almost perfect inter-observer reliability with mean κ-coefficients > 0.81. However, intra-observer reliability was fair-to-moderate with mean κ-coefficients between 0.22-0.58. Three tests achieved moderate intra-observer reliability with κ-coefficients > 0.41. Combinations of one low- and one high-threshold test best discriminated prior back pain, but results were inconsistent for lower-extremity pain.ConclusionsOur results suggest that clinical tests of movement control of back and hip are reliable for use in screening protocols using several observers with marines. However, test-retest reproducibility was less accurate, which should be considered in follow-up evaluations. The results also indicate that combinations of low- and high-threshold tests have discriminative validity for prior back pain, but were inconclusive for lower-extremity pain.

Does a dynamic chair increase office workers' movements? – Results from a combined laboratory and field study

PURPOSE Dynamic chairs have the potential to facilitate movements that could counteract health problems associated with sedentary office work. This study aimed to evaluate whether a dynamic chair can increase movements during desk-based office work. METHODS Fifteen healthy subjects performed desk-based office work using a dynamic office chair and compared to three other conditions in a movement laboratory. In a field study, the dynamic office chair was studied during three working days using accelerometry. RESULTS Equivocal results showed that the dynamic chair increased upper body and chair movements as compared to the conventional chair, but lesser movements were found compared to standing. No differences were found between the conditions in the field study. CONCLUSIONS A dynamic chair may facilitate movements in static desk-based office tasks, but the results were not consistent for all outcome measures. Validation of measuring protocols for assessing movements during desk-based office work is warranted.

Musculoskeletal pain and related risks in skydivers: A population-based survey

INTRODUCTION Sport parachuting from aircraft (skydiving) is a major aerial activity in which parachutists are subject to decelerating forces during parachute opening shock (POS), possibly as much as 3-5 G. While traumatic incidents related to POS have been reported, epidemiological data on musculoskeletal pain among skydivers is absent in the literature. The aim was therefore to examine the prevalence of self-rated musculoskeletal pain related to POS in a skydiver population and elicit related risk factors. METHODS There were 658 Swedish sport skydivers who completed a structured web-based questionnaire (70% response rate; email invitation) validated for use in skydivers. The questionnaire concerned individual and skydiving-related risk indicators, and musculoskeletal pain experiences. Multiple regression analysis was used to estimate the relationship between risk indicators and musculoskeletal pain related to POS. RESULTS The 12-mo prevalence of musculoskeletal pain related to POS was highest for the neck region, 25% (95% CI = 21.4-28.2). Other upper-body regions were as follows: shoulder 16% thoracic spine 10%, and lower back 18%. A high number of parachute jumps in the last 12 mo, i.e., 30-90 jumps (RR = 1.7, 95% CI = 1.1-2.7), > 90 jumps (RR = 2.1, 95% CI = 1.3-3.4), and a high main parachute wing-loading, i.e., > 1.4 lb/ft2 (RR = 1.7, 95% CI = 1.1-2.6) were independent risk factors. CONCLUSIONS Neck pain related to POS was common among skydivers. A high number of parachute jumps the last 12 mo and high wing-loading emerged as risk factors, suggesting that highly active skydivers using small canopies may be at risk. Studies on biomechanics under POS are suggested.

Reliability of measurements of wrist extension force obtained with a Nicholas Manual Muscle Tester (NMMT)

The primary aim was to determine the intra- and interexaminer reliability of measurements of isometric wrist extension force obtained with the Nicholas Manual Muscle Tester (NMMT) in a “break test.” A secondary aim was to use NMMT measurements to describe the relation between electromyographic (EMG) activity and force produced in wrist extensors at different levels of contraction strain. Two examiners tested 51 healthy subjects (aged 19–46) in a test-retest approach with 6–7 days between the tests. Eleven subjects from this sample were also recruited for the study investigating the relation between EMG and force in the wrist extensor. Intraexaminer reliability was excellent for both examiners (ICC 0.944 and 0.902). The results also showed excellent interexaminer reliability (ICC 0.925) and relatively low CV% and Sdiff. The EMG-force relation in wrist extensor muscles was strong (r = 0.985). The excellent test-retest stability indicates that measurements of isometric wrist extension force obtained with NMMT are appropriate for clinical evaluation as well as for further studies of wrist isometric extensor muscle strength. The tests indicated that the relation between force produced and levels of EMG activity in wrist extensor muscles is approximately linear.

Neck muscle activity in skydivers during parachute opening shock.

This observational study investigated skydiver neck muscle activity during parachute opening shock (POS), as epidemiological data recently suggested neck pain in skydivers to be related to POS. Twenty experienced skydivers performed two terminal velocity skydives each. Surface electromyography quantified muscle activity bilaterally from the anterior neck, the upper and lower posterior neck, and the upper shoulders; and two triaxial accelerometers sampled deceleration. Muscle activity was normalized as the percentage of reference maximum voluntary electrical activity (% MVE); and temporal muscle activity onset was related to POS onset. Our results showed that neck muscle activity during POS reached mean magnitudes of 53–104% MVE, often exceeding reference activity in the lower posterior neck and upper shoulders. All investigated muscle areas’ mean temporal onsets occurred <50 ms after POS onset (9–34 ms latencies), which is consistent with anticipatory motor control. The high muscle activity observed supports that the neck is under substantial strain during POS, while temporal muscle activation suggests anticipatory motor control to be a strategy used by skydivers to protect the cervical spine from POS. This studys findings contribute to understanding the high rates of POS‐related neck pain, and further support the need for evaluation of neck pain preventative strategies.