Ernst Albin Hansen

Effect of physical exercise interventions on musculoskeletal pain in all body regions among office workers: A one-year randomized controlled trial

This study investigated effects of physical exercise on musculoskeletal pain symptoms in all regions of the body, as well as on other musculoskeletal pain in association with neck pain. A single blind randomized controlled trial testing a one-year exercise intervention was performed among 549 office workers; specific neck/shoulder resistance training, all-round physical exercise, or a reference intervention. Pain symptoms were determined by questionnaire screening of twelve selected body regions. Case individuals were identified for each body region as those reporting pain intensities at baseline of 3 or more (scale of 0-9) during the last three months. For neck cases specifically, the additional number of pain regions was counted. Intensity of pain decreased significantly more in the neck, low back, right elbow and right hand in cases of the two exercise groups compared with the reference group (P<0.0001-0.05). The additional number of pain regions in neck cases decreased in the two exercise groups only (P<0.01-0.05). In individuals with no or minor pain at baseline, development of pain was minor in all three groups. In conclusion, both specific resistance training and all-round physical exercise for office workers caused better effects than a reference intervention in relieving musculoskeletal pain symptoms in exposed regions of the upper body.

A Randomized Controlled Intervention Trial to Relieve and Prevent Neck/Shoulder Pain.

PURPOSE The objective of this study is to investigate the effect of three different workplace interventions on long-term compliance, muscle strength gains, and neck/shoulder pain in office workers. METHODS A 1-yr randomized controlled intervention trial was done with three groups: specific resistance training (SRT, n = 180), all-round physical exercise (APE, n = 187), and reference intervention (REF, n = 182) with general health counseling. Physical tests were performed and questionnaires answered at pre-, mid-, and postintervention. The main outcome measures were compliance, changes in maximal muscle strength, and changes in intensity of neck/shoulder pain (scale 0-9) in those with and without pain at baseline. RESULTS Regular participation was achieved by 54%, 31%, and 16% of those of the participants who answered the questionnaire in SRT (78%), APE (81%), and REF (80%), respectively, during the first half of the intervention period, and decreased to 35%, 28% and 9%, respectively, during the second half. Shoulder elevation strength increased 9-11% in SRT and APE (P < 0.0001). Participants with neck pain at baseline decreased the intensity of neck pain through SRT, from 5.0 +/- 0.2 to 3.4 +/- 0.2 (P < 0.0001), and through APE, from 5.0 +/- 0.2 to 3.6 +/- 0.2 (P < 0.001), whereas REF caused no change. For participants without shoulder pain at baseline, there was a significantly greater increase in pain over the 1-yr period in REF compared with SRT and APE (P < 0.01). CONCLUSION Compliance was highest in SRT but generally decreased over time. SRT and APE caused increased shoulder elevation strength, were more effective than REF to decrease neck pain among those with symptoms at baseline, and prevent development of shoulder pain in those without symptoms at baseline.

The effect of worksite physical activity intervention on physical capacity, health, and productivity: a 1-year randomized controlled trial.

Objective: To investigate the effect of two contrasting physical activity worksite interventions versus a reference intervention (REF) on various health outcomes. Methods: A 1-year randomized controlled trial was conducted with specific resistance training (SRT), all-round physical exercise (APE), and REF. Results: SRT and APE compared with REF showed significant reductions in systolic blood pressure (∼6 mm Hg), body fat percentage (∼2.2 body fat%), as well as shoulder and back pain (∼30% reduction in duration). Muscle strength (APE and SRT) and maximal oxygen uptake (APE) increased approximately 10%. Conclusions: Worksite intervention with both SRT as well as APE is recommended, since these activities compared with REF resulted in clinically relevant reductions of cardiovascular and metabolic syndrome-related risk factors as well as musculoskeletal pain symptoms, in combination with minor increases in physical capacity.

Strength training improves 5-min all-out performance following 185 min of cycling

To investigate the effects of heavy strength training on the mean power output in a 5‐min all‐out trial following 185 min of submaximal cycling at 44% of maximal aerobic power output in well‐trained cyclists. Twenty well‐trained cyclists were assigned to either usual endurance training combined with heavy strength training [E+S; n=11 (♂=11)] or to usual endurance training only [E; n=9 (♂=7, ♀=2)]. The strength training performed by E+S consisted of four lower body exercises [3 × 4–10 repetition maximum (RM)], which were performed twice a week for 12 weeks. E+S increased 1 RM in half‐squat (P≤0.001), while no change occurred in E. E+S led to greater reductions than E in oxygen consumption, heart rate, blood lactate concentration, and rate of perceived exertion (P<0.05) during the last hour of the prolonged cycling. Further, E+S increased the mean power output during the 5‐min all‐out trial (from 371 ± 9 to 400 ± 13 W, P<0.05), while no change occurred in E. In conclusion, adding strength training to usual endurance training improves leg strength and 5‐min all‐out performance following 185 min of cycling in well‐trained cyclists.

Energy Expenditure and Comfort During Nordic Walking With Different Pole Lengths

Hansen, EA and Smith, G. Energy expenditure and comfort during Nordic walking with different pole lengths. J Strength Cond Res 23(4): 1187-1194, 2009-Energy expenditure and comfort for Nordic walking with self-selected and 7.5-cm shorter poles and ordinary walking were measured during uphill (12°), downhill (12°), and horizontally. Twelve (11 women and 1 man) Nordic walking practitioners participated (mean ± SEM: 171.5 ± 1.5 cm, 67.0 ± 2.7 kg, 50.6 ± 2.4 years, and maximal oxygen uptake of 43.4 ± 2.8 mL·kg−1·min−1). Energy expenditure was calculated from oxygen uptake and comfort was self-rated. Differences in physiological responses between the 3 locomotion types at each slope were first analyzed by a 1-way analysis of variance. In case of significance, Students paired samples 2-tailed t-test was applied twice to test for differences between the 2 pole lengths and between Nordic walking (with self-selected pole length) and ordinary walking. The corresponding differences in comfort were evaluated by a Wilcoxon matched pairs test. The relative exercise intensity during Nordic walking with self-selected pole length ranged between ∼44 and 87% of the maximal oxygen uptake across the different slopes. For comparison, it ranged between ∼29 and 80% during ordinary walking. Uphill Nordic walking with short poles compared with poles of self-selected length caused 3% greater energy expenditure. Notwithstanding, comfort was similar. Horizontally and downhill energy expenditure and comfort were similar between pole lengths. Compared with ordinary walking, Nordic walking required as much as 67% greater energy expenditure. Comfort was similar for ordinary and Nordic walking for each slope. In conclusion, shorter poles caused greater energy expenditure during uphill Nordic walking, whereas comfort was similar to poles of self-selected length. The substantially enhanced energy expenditure of Nordic walking compared with previous studies reflects the vigorous technique used here.

Seated versus standing position for maximization of performance during intense uphill cycling

Abstract It is not known whether the seated or standing position favours performance during intensive bouts of uphill cycling. The following hypotheses were therefore tested: (1) the standing position results in better performance at a high power output, while (2) the seated position is best at a moderate power output. We also assessed the seated–standing transition intensity, above which seated cycling should be superseded by standing cycling for maximization of performance. Ten male cyclists (mean age 27 years, s = 3; height 1.82 m, s = 0.07; body mass 75.2 kg, s = 7.0; [Vdot]O2max 70.0 ml · kg−1 · min−1, s = 5.2) performed seated and standing treadmill cycling to exhaustion at 10% grade and at four power outputs ranging from 86% to 165% of their power output at maximal oxygen uptake (Wmax). Power output at maximal oxygen uptake was obtained during determination of [Vdot]O2max. There was no difference in time to exhaustion between the two cycling positions at 86% of Wmax (P = 0.29). All participants performed best at the highest power output (165% of Wmax) when standing (P = 0.002). An overall seated–standing transition intensity of 94% of Wmax was identified. Thus, in general, cyclists may choose either the standing or seated position for maximization of performance at a submaximal intensity of 86% of Wmax, while the standing position should be used at intensities above 94% of Wmax and approaching 165% of Wmax.

Relationship between efficiency and pedal rate in cycling: significance of internal power and muscle fiber type composition

Cycling was performed to test the following two hypotheses: (1) muscular efficiency is unrelated to pedal rate (61, 88, and 115 r.p.m.) for a group of subjects with a wide range of slow twitch (ST) fibers in spite of decreasing whole‐body efficiency and (2) muscular efficiency correlates positively with % ST muscle fibers, and this correlation is more pronounced at low pedal rates than at high pedal rates.

Inter-subject variability of muscle synergies during bench press in power lifters and untrained individuals

The purpose of the study was to elucidate the role of expertise on muscle synergies involved in bench press. Ten expert power lifters (EXP) and nine untrained participants (UNT) completed three sets of eight repetitions at 60% of three repetition maximum in bench press. Muscle synergies were extracted from surface electromyography data of 21 bench press cycles using non‐negative matrix factorization algorithm. The synergy activation coefficient represents the relative contribution of the muscle synergy to the overall muscle activity pattern, while the muscle synergy vector represents the relative weighting of each muscle within each synergy. Describing more than 90% of the variability, two muscle synergies reflected the eccentric and concentric phase. The cross‐correlations (ρmax) for synergy activation coefficient 2 (concentric phase) were 0.83 [0.71;0.88] and 0.59 [0.49;0.77] [Median ρmax (25th;75th percentile)] (P = 0.001) in UNT and EXP, respectively. Median correlation coefficient (ρ) for muscle synergy vector 2 was 0.15 [−0.08;0.46] and 0.48 [0.02;0.70] (P = 0.03) in UNT and EXP, respectively. Thus, EXP showed larger inter‐subject variability than UNT in the synergy activation coefficient during the concentric phase, while the muscle synergy vectors were less variable in EXP. This points at the importance of a specialized neural strategy in elite bench press performance.

Strength training affects tendon cross-sectional area and freely chosen cadence differently in noncyclists and well-trained cyclists

Rønnestad, BR, Hansen, EA, and Raastad, T. Strength training affects tendon cross-sectional area and freely chosen cadence differently in noncyclists and well-trained cyclists. J Strength Cond Res 26(1): 158–166, 2012—The effects of strength training on freely chosen cadence and physiological responses in cyclists and recreationally active individuals were investigated. Well-trained cyclists were assigned to either usual endurance training combined with strength training (C-ES; n = 11) or usual endurance training only (C-E; n = 9). Recreationally active individuals (R-S; n = 7) performed the same strength training as C-ES did (4 lower body exercises, 3 × 4–10 repetition maximum [RM], twice a week for 12 weeks). The R-S and C-ES increased 1RM to a similar extent after 4 and 12 weeks (p < 0.01), whereas 1RM remained unchanged in C-E. Only R-S increased patellar tendon cross-sectional area (CSA; 7 ± 1%, p < 0.001). After 4 weeks, R-S reduced freely chosen cadence, oxygen consumption, heart rate, rating of perceived exertion, and blood lactate concentration during cycling at 125 W. These responses remained reduced throughout the intervention period (p < 0.05). No significant changes were observed in these physiological variables in C-ES and C-E. In conclusion, freely chosen cadence during submaximal cycling was reduced in recreationally active individuals after a period of strength training but was not reduced in well-trained cyclists. The reduced freely chosen cadence may be associated with the observed increase in patellar tendon CSA through a morphological-sensory-motor interaction. A practical application is that heavy strength training can reduce freely chosen cadence during submaximal cycling and thereby improve cycling economy in recreationally active individuals, whereas other mechanisms should account for improved performance after strength training in well-trained cyclists.

On voluntary rhythmic leg movement behaviour and control during pedalling

The overall purpose of the present dissertation was to contribute to the understanding of voluntary human rhythmic leg movement behaviour and control. This was achieved by applying pedalling as a movement model and exposing healthy and recreationally active individuals as well as trained cyclists to for example cardiopulmonary and mechanical loading, fatiguing exercise, and heavy strength training. As a part of the background, the effect of pedalling frequency on diverse relevant biomechanical, physiological, and psychophysiological variables as well as on performance was initially explored. Freely chosen pedalling frequency is considerably higher than the energetically optimal pedalling frequency. This has been shown by others and was confirmed in the present work. As a result, pedal force is relatively low while rates of VO2 and energy turnover are relatively high during freely chosen pedalling as compared to a condition where a lower and more efficient pedalling frequency is imposed. The freely chosen pedalling frequency was in the present work, and by others, found to most likely be less advantageous than the lower energetically optimal pedalling frequency with respect to performance during intensive cycling following prolonged submaximal cycling. This stimulates the motivation to understand the behaviour and control of the freely chosen pedalling frequency during cycling. Freely chosen pedalling frequency was in the present work shown to be highly individual. In addition, the pedalling frequency was shown to be steady in a longitudinal perspective across 12 weeks. Further, it was shown to be unaffected by both fatiguing hip extension exercise and hip flexion exercise as well as by increased loading on the cardiopulmonary system at constant mechanical loading, and vice versa. Based on this, the freely chosen pedalling frequency is considered to be characterised as a highly individual, steady, and robust innate voluntary motor rhythm under primary influence of central pattern generators. The last part of the characterisation is largely based on, and supported by, work of other researchers in the field. Despite the robustness of the freely chosen pedalling frequency, it may be affected by some particular factors. As an example from the present work, freely chosen pedalling frequency during treadmill cycling increased by on average 15 to 17 rpm when power output was increased from a value corresponding to 86% and up to 165% of Wmax. This phenomenon is supported by other studies. As another example from the present work, freely chosen pedalling frequency decreased by on average 9 to 14 rpm following heavy strength training that involved both hip extension and hip flexion. Further, the present work suggested that the latter phenomenon occurred within the first week of training and was caused by in particular the hip extension strength training rather than the hip flexion strength training. The fast response to the strength training indicated that neural adaptations presumably caused the observed changes in movement behaviour. The internal organisation of the central pattern generator is by some other researchers in the field considered to be functionally separated into two components, in which, one is responsible for movement frequency and another is responsible for movement pattern. For the present dissertation, the freely chosen pedalling frequency was considered to reflect the rhythmic movement frequency of the voluntary rhythmic leg movement of pedalling. The tangential pedal force profile was considered to reflect the rhythmic movement pattern. The present work showed that fatiguing hip flexion exercise in healthy and recreationally active individuals modified the tangential pedal force profile during cycling at a pre‐set target pedalling frequency in a way that the minimum tangential pedal force became more negative, the maximum tangential pedal force increased, and the phase with negative tangential pedal force increased. In other words, the legs were “actively lifted” to a lesser extent in the upstroke phase. Fatiguing hip extension exercise did not have that effect. And none of the fatiguing exercises affected the freely chosen pedalling frequency. The present work furthermore showed that the primary effect of hip extension strength training was that it decreased the freely chosen pedalling frequency. An interpretation of this could be that the hip extension strength training, in particular, influenced the output from the component of the central pattern generator that may be responsible for rhythmic movement frequency.