Peter Paasch Mortensen

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.

Acute fatigue impairs neuromuscular activity of anterior cruciate ligament‐agonist muscles in female team handball players

In sports, like team handball, fatigue has been associated with an increased risk of anterior cruciate ligament (ACL) injury. While effects of fatigue on muscle function are commonly assessed during maximal isometric voluntary contraction (MVC), such measurements may not relate to the muscle function during match play. The purpose of this study was to investigate the effect of muscle fatigue induced by a simulated handball match on neuromuscular strategy during a functional sidecutting movement, associated with the incidence of ACL injury. Fourteen female team handball players were tested for neuromuscular activity [electromyography (EMG)] during a sidecutting maneuver on a force plate, pre and post a simulated handball match. MVC was obtained during maximal isometric quadriceps and hamstring contraction. The simulated handball match consisted of exercises mimicking handball match activity. Whereas the simulated handball match induced a decrease in MVC strength for both the quadriceps and hamstring muscles (P<0.05), a selective decrease in hamstring neuromuscular activity was seen during sidecutting (P<0.05). This study shows impaired ACL‐agonist muscle (i.e. hamstring) activity during sidecutting in response to acute fatigue induced by handball match play. Thus, screening procedures should involve functional movements to reveal specific fatigue‐induced deficits in ACL‐agonist muscle activation during high‐risk phases of match play.

Kettlebell swing targets semitendinosus and supine leg curl targets biceps femoris: an EMG study with rehabilitation implications.

Background The medial hamstring muscle has the potential to prevent excessive dynamic valgus and external rotation of the knee joint during sports. Thus, specific training targeting the medial hamstring muscle seems important to avoid knee injuries. Objective The aim was to investigate the medial and lateral hamstring muscle activation balance during 14 selected therapeutic exercises. Study design The study design involved single-occasion repeated measures in a randomised manner. Sixteen female elite handball and soccer players with a mean (SD) age of 23 (3) years and no previous history of knee injury participated in the present study. Electromyographic (EMG) activity of the lateral (biceps femoris – BF) and medial (semitendinosus – ST) hamstring muscle was measured during selected strengthening and balance/coordination exercises, and normalised to EMG during isometric maximal voluntary contraction (MVC). A two-way analysis of variance was performed using the mixed procedure to determine whether differences existed in normalised EMG between exercises and muscles. Results Kettlebell swing and Romanian deadlift targeted specifically ST over BF (Δ17–22%, p<0.05) at very high levels of normalised EMG (73–115% of MVC). In contrast, the supine leg curl and hip extension specifically targeted the BF over the ST (Δ 20–23%, p<0.05) at very high levels of normalised EMG (75–87% of MVC). Conclusion Specific therapeutic exercises targeting the hamstrings can be divided into ST dominant or BF dominant hamstring exercises. Due to distinct functions of the medial and lateral hamstring muscles, this is an important knowledge in respect to prophylactic training and physical therapist practice.

Dose-response of strengthening exercise for treatment of severe neck pain in women

Abstract Andersen, CH, Andersen, LL, Pedersen, MT, Mortensen, P, Karstad, K, Mortensen, OS, Zebis, MK, and Sjøgaard, G. Dose-response of strengthening exercise for treatment of severe neck pain in women. J Strength Cond Res 27(12): 3322–3328, 2013—Specific strength training is shown to relieve neck pain in office workers. The purpose of this study is to evaluate the effectiveness of specific strength training in women with severe neck pain and to analyze the dose–response relationship between training adherence and pain reduction. One hundred eighteen untrained women with severe neck pain (>30 mm VAS pain) were included from a larger study, in which the subjects were randomized to 20-week specific strength training for the neck/shoulders or to a control group. In the intention-to-treat analysis, the training group experienced greater pain relief than the control group (p < 0.01). Participants who adhered “per protocol” decreased pain by 35 mm VAS (95% confidence interval: −26 to −44) from baseline to follow-up corresponding to a 70% reduction. In the dose–response analyses, participants with medium and high training adherence showed better pain relief than the control group and those with low adherence (p < 0.0001). The decrease from baseline in the medium and high adherence groups was 37 mm VAS (28–46 mm) and 33 mm VAS (24–43 mm), respectively. Specific strength training reduces pain intensity in women with severe neck pain, and 1–2 training sessions per week for 20 weeks (∼30 training sessions) seems sufficient for optimal pain relief.

Evaluation of Muscle Activity During a Standardized Shoulder Resistance Training Bout in Novice Individuals

Abstract Jakobsen, MD, Sundstrup, E, Andersen, CH, Zebis, MK, Mortensen, P, and Andersen, LL. Evaluation of muscle activity during a standardized shoulder resistance training bout in novice individuals. J Strength Cond Res 26(9): 2515–2522, 2012—Momentary fatigue is an important variable in resistance training periodization programs. Although several studies have examined neuromuscular activity during single repetitions of resistance training, information is lacking in regard to neuromuscular fatigue indices throughout a full resistance training bout. The purpose of this study was to evaluate muscle activity during a shoulder resistance training bout with 15 repetitions maximum (RM) loadings in novice individuals. Twelve healthy sedentary women (age = 27–58 years; weight = 54–85 kg; height = 160–178 cm) were recruited for this study. Normalized electromyographic (nEMG) activity and median power frequency (MPF) of the upper, medial, and lower trapezius; the medial deltoid, infraspinatus, and serratus anterior was measured during 3 sets of 15RM during the exercises front raise, reverse flyes, shrugs, and lateral raise. For the majority of exercises, nEMG activity was high (>60% of maximal isometric contractions). From the first to the last repetition of each set nEMG—averaged for all muscles—increased 10. 0 ± 0.4% (p < 0.05) and MPF decreased −7.7 ± 0.5 Hz (p < 0.05). By contrast, nEMG activity and MPF were unchanged from the first to the third set (averaged for all muscles: 38.1 ± 23.6 vs. 47.6 ± 28.8% and 88.4 ± 21.3 vs. 82.1 ± 18.1 Hz, respectively). In conclusion, during a shoulder resistance training bout in novice individuals using 15RM loading muscle activity of the upper, medial, and lower trapezius, the medial deltoid, infraspinatus, and serratus anterior increased, and MPF decreased within each set—indicating momentary neuromuscular fatigue. By contrast, no such change was observed between the 3 sets. This indicates that momentary neuromuscular fatigue in shoulder resistance training is induced more efficiently within a set than between sets.

Lasting effects of workplace strength training for neck/shoulder/arm pain among laboratory technicians: natural experiment with 3-year follow-up

Objectives. This study investigated long-term effects and implementation processes of workplace strength training for musculoskeletal disorders. Methods. 333 and 140 laboratory technicians from private and public sector companies, respectively, replied to a 3-year follow-up questionnaire subsequent to a 1-year randomized controlled trial (RCT) with high-intensity strength training for prevention and treatment of neck, shoulder, and arm pain. Being a natural experiment, the two participating companies implemented and modified the initial training program in different ways during the subsequent 2 years after the RCT. Results. At 3-year follow-up the pain reduction in neck, shoulder, elbow, and wrist achieved during the first year was largely maintained at both companies. However, the private sector company was rated significantly better than the public sector company in (1) training adherence, (2) training culture, that is, relatively more employees trained at the workplace and with colleagues, (3) self-reported health changes, and (4) prevention of neck and wrist pain development among initially pain-free employees. Conclusions. This natural experiment shows that strength training can be implemented successfully at different companies during working hours on a long-term basis with lasting effects on pain in neck, shoulder, and arm.