Classification of kneeling and squatting in workers wearing protective equipment: development and validation of a rule-based model using wireless triaxial accelerometers.

Several professions in industries, such as petroleum, manufacturing, construction, mining, and forestry require prolonged work tasks in awkward postures, increasing workers' risks for musculoskeletal pain and injury. Therefore, we developed and validated a rule-based model for classifying unilateral and bilateral kneeling and squatting based on 15 individuals wearing personal protective equipment and using three wireless triaxial accelerometers. The model provided both high sensitivity and specificity for classifying kneeling (0.98; 0.98) and squatting (0.96; 0.91). Hence, this model has the potential to contribute to increased knowledge of physical work demands and exposure thresholds in working populations with strict occupational safety regulations. Practitioner summary: Our results indicate that this rule-based model can be applied in a human-factors perspective enabling high-quality quantitative information in the classification of occupational kneeling and squatting, known risk factors for musculoskeletal pain, and sick leave. This study is adapted for working populations wearing personal protective equipment and aimed for long-term measurements in the workplace.

Design of a study evaluating the effects, health economics, and stakeholder perspectives of a multi-component occupational rehabilitation program with an added workplace intervention - a study protocol.

BACKGROUND: Recent research has suggested that interventions at the workplace might be the most potent ingredient in return to work interventions, but few studies have investigated the different effects of workplace interventions as part of occupational rehabilitation programs. The comprehensive design described in this article includes effect (on return to work and health outcomes), and health economic evaluations of a workplace intervention added to a multicomponent rehabilitation program. Qualitative and mixed method studies will investigate sick-listed persons', rehabilitation therapists' and employers' perspectives on the usability and outcomes of the rehabilitation program and the workplace intervention. The program and intervention are provided to patients with musculoskeletal, psychological or general and unspecified diagnoses. The program is multi-component and includes Acceptance and Commitment Therapy, physical exercise, patient education and creating a plan for increased work participation. METHODS: Persons who are employed, aged from 18 to 60 years, with a current sick leave status of 50% or more and a diagnosis within the musculoskeletal, psychological or general and unspecified chapters of International Classification of Primary Care-2 (ICPC-2) will be recruited to a researcher-blinded parallel-group randomized controlled trial. All participants take part in an in-patient occupational rehabilitation program, while the intervention group also takes part in an intervention at the workplace. The effect and economic evaluation will investigate the effect of the added workplace intervention. The primary outcome measures will be time until full sustainable return to work and total number of sickness absence days in the 12 months after inclusion. Health economic evaluations will investigate the cost-effectiveness and cost-utility. Qualitative studies will investigate rehabilitation therapists' experiences with working towards return to work within an ACT-approach and stakeholders' experiences with the workplace intervention. A mixed methods study will combine quantitative and qualitative findings on the participants' expectations and motivation for return to work. DISCUSSION: The outline of this comprehensive study could represent an important addition to the standard designs of return to work evaluation. The mixed methods design, with qualitative approaches as well as a rigorous randomized controlled trial, might prove useful to shed light on contextual factors. TRIAL REGISTRATION: ClinicalTrials.gov : NCT02541890 . September 4, 2015.

Unfolding the values of work - therapists´ experience of addressing the return to work process in occupational rehabilitation based on Acceptance and Commitment Therapy.

BACKGROUND: Facilitating return to work can be challenging due to the complexity of work disability. Few studies have examined rehabilitation programs based on Acceptance and Commitment Therapy that intend to support return to work, and none have investigated therapists' experience with providing such programs. The aim of this study was therefore to explore therapists' experience of addressing the return to work process in an inpatient occupational rehabilitation program based on Acceptance and Commitment Therapy. METHODS: This was a qualitative interview study supported by participant observation. Therapists were interviewed regarding their experiences with addressing return to work in an inpatient occupational rehabilitation program based on Acceptance and Commitment Therapy. In addition, the rehabilitation program was investigated through participant observation. The interviews were analysed according to Interpretative Phenomenological Analysis and informed by an analysis of field notes from the participant observation. RESULTS: Acceptance and Commitment Therapy was experienced as a meaningful approach to facilitate return to work, as it allowed therapists to address all relevant aspects of the individual participant's life that might influence work participation. The therapists' twofold goal was to support participants in building both a meaningful life and sustainable work participation. To do so, they attempted to instil long-term and interrelated processes concerning ownership, causes of sick leave, relation to expectations, the values of work, and the scope of agency. CONCLUSION: Unfolding values connected to work participation might reconcile the tension between work and family life by integrating work with other areas of life. Providing work participation with personal meaning also seems especially commensurable with a context where economy presents a poor incentive for return to work. Therapists should, however, be attentive to the need to secure the prominence of return to work by relating participants' chosen themes explicitly to their return to work process. Therapists should also be aware of the dilemma that may arise when they attempt to refrain from providing advice while simultaneously encouraging actions they consider appropriate to facilitate sustainable work participation. In addition, having an individual-oriented approach to occupational rehabilitation may obscure the extent to which return to work is a multi-stakeholder process.

Electromyographic Comparison of Barbell Deadlift, Hex Bar Deadlift, and Hip Thrust Exercises: A Cross-Over Study.

Andersen, V, Fimland, MS, Mo, D-A, Iversen, VM, Vederhus, T, Rockland Hellebø, LR, Nordaune, KI, and Saeterbakken, AH. Electromyographic comparison of barbell deadlift, hex bar deadlift, and hip thrust exercises: a cross-over study. J Strength Cond Res 32(3): 587-593, 2018-The aim of the study was to compare the muscle activation level of the gluteus maximus, biceps femoris, and erector spinae in the hip thrust, barbell deadlift, and hex bar deadlift; each of which are compound resisted hip extension exercises. After 2 familiarization sessions, 13 resistance-trained men performed a 1 repetition maximum in all 3 exercises in 1 session, in randomized and counterbalanced order. The whole ascending movement (concentric phase), as well as its lower and upper parts (whole movement divided in 2), were analyzed. The hip thrust induced greater activation of the gluteus maximus compared with the hex bar deadlift in the whole (16%, p = 0.025) and the upper part (26%, p = 0.015) of the movement. For the whole movement, the biceps femoris was more activated during barbell deadlift compared with both the hex bar deadlift (28%, p < 0.001) and hip thrust (20%, p = 0.005). In the lower part of the movement, the biceps femoris activation was, respectively, 48% and 26% higher for the barbell deadlift (p < 0.001) and hex bar deadlift (p = 0.049) compared with hip thrust. Biceps femoris activation in the upper part of the movement was 39% higher for the barbell deadlift compared with the hex bar deadlift (p = 0.001) and 34% higher for the hip thrust compared with the hex bar deadlift (p = 0.002). No differences were displayed for the erector spinae activation (p = 0.312-0.859). In conclusion, the barbell deadlift was clearly superior in activating the biceps femoris compared with the hex bar deadlift and hip thrust, whereas the hip thrust provided the highest gluteus maximus activation.

Core Muscle Activation in One-Armed and Two-Armed Kettlebell Swing.

The aim of the study was to compare the electromyographic activity of rectus abdominis, oblique external, and lower and upper erector spinae at both sides of the truncus in 1-armed and 2-armed kettlebell swing. Sixteen healthy men performed 10 repetitions of both exercises using a 16-kg kettlebell in randomized order. For the upper erector spinae, the activation of the contralateral side during 1-armed swing was 24% greater than that of the ipsilateral side during 1-armed swing (p < 0.001) and 11% greater during 2-armed swing (p = 0.026). Furthermore, the activation in 2-armed swing was 12-16% greater than for the ipsilateral side in 1-armed swing (p < 0.001). For rectus abdominis, however, 42% lower activation of the contralateral side was observed during 1-armed swing compared with ipsilateral sides during 2-armed swing (p = 0.038) and 48% compared with the ipsilateral side during 1-armed swing (p = 0.044). Comparing the different phases of the swing, most differences in the upper erector spinae were found in the lower parts of the movement, whereas for the rectus abdominis, the differences were found during the hip extension. In contrast, similar muscle activity in the lower erector spinae and external oblique between the different conditions was observed (p = 0.055-0.969). In conclusion, performing the kettlebell swing with 1 arm resulted in greater neuromuscular activity for the contralateral side of the upper erector spinae and ipsilateral side of the rectus abdominis, and lower activation of the opposite side of the respective muscles.

Sick-listed persons' experiences with taking part in an in-patient occupational rehabilitation program based on Acceptance and Commitment Therapy: a qualitative focus group interview study.

BACKGROUND: Occupational medicine has shifted emphasis from disease treatment to disability rehabilitation and management. Hence, newly developed occupational rehabilitation programs are often generic and multicomponent, aiming to influence the sick-listed persons' perception on return to work, and thereby support the return to work process. The aim of this study was to explore sick-listed persons' experiences with taking part in an in-patient occupational rehabilitation program based on Acceptance and Commitment Therapy. METHODS: Twenty-nine adults on sickness benefit or work assessment allowance due to musculoskeletal and/or common mental health disorders participated in this study. They were interviewed in focus groups at the beginning and at the end of a 3.5 week inpatient group-based occupational rehabilitation program in Central Norway. Key elements in the program were Acceptance and Commitment Therapy (ACT), physical exercise and creating a work-participation plan. The program was mainly group-based including participants with different diagnoses. Data was analyzed according to a phenomenological approach. RESULTS: At the start of the program most participants expressed frustration regarding being sick-listed, external anticipations as well as hindrances towards returning to work, and described hope that the program would provide them with the skills and techniques necessary to cope with health problems and being able to return to work. At the end of the program the participants described that they had embarked upon a long process of increased awareness. This process encompassed four areas; an increased awareness of what was important in life, realizing the strain from external expectations and demands, a need to balance different aspects of life, and return to work as part of a long and complex process. CONCLUSIONS: The occupational rehabilitation program induced a perceived meaningful reorientation encompassing several aspects of life. However, the return to work process was described as diffuse and uncertain for most participants. The providers of occupational rehabilitation program should balance this reorientation with specific steps towards return to work. Effect studies and long-term qualitative studies evaluating how this affects long-term work- and health outcomes are underway.

Elastic Bands in Combination With Free Weights in Strength Training: Neuromuscular Effects.

This study compared the effects of a variable vs. a constant lower limb resistance training program on muscle strength, muscle activation, and ballistic muscle performance at different knee angles. Thirty-two females were randomized to a constant resistance training free-weight group (FWG) or a variable resistance training group using free weights in combination with elastic bands (EBG). Two variations of the squat exercise (back squat and split) were performed 2 days per week for 10 weeks. Knee extensor maximal voluntary isometric contraction (MVC) and countermovement jump were assessed at knee angles of 60, 90, and 120° before and after the intervention. During the MVCs, muscle activation of the superficial knee extensor muscles was measured using surface electromyography. The FWG increased their MVCs at 60 and 90° (24 and 15%, respectively), whereas the EBG only increased significantly at 60° (15%). The FWG increased their jump height significantly at all angles (12-16%), whereas the EBG only improved significantly at 60 and 90° (15 and 10%, respectively). Both groups improved their 6-repetition maximum free-weight squat performance (EBG: 25% and FWG: 23%). There were no significant changes in muscle activation. In conclusion, constant and variable resistance training provided similar increases in dynamic and isometric strength, and ballistic muscle performance, albeit most consistently for the group training only with free weights.

Occupational rehabilitation programs for musculoskeletal pain and common mental health disorders: study protocol of a randomized controlled trial.

BACKGROUND: Long-term sick leave has considerably negative impact on the individual and society. Hence, the need to identify effective occupational rehabilitation programs is pressing. In Norway, group based occupational rehabilitation programs merging patients with different diagnoses have existed for many years, but no rigorous evaluation has been performed. The described randomized controlled trial aims primarily to compare two structured multicomponent inpatient rehabilitation programs, differing in length and content, with a comparative cognitive intervention. Secondarily the two inpatient programs will be compared with each other, and with a usual care reference group. METHODS/DESIGN: The study is designed as a randomized controlled trial with parallel groups. The Social Security Office performs monthly extractions of sick listed individuals aged 18-60 years, on sick leave 2-12 months, with sick leave status 50% - 100% due to musculoskeletal, mental or unspecific disorders. Sick-listed persons are randomized twice: 1) to receive one of two invitations to participate in the study or not receive an invitation, where the latter "untouched" control group will be monitored for future sick leave in the National Social Security Register, and 2) after inclusion, to a Long or Short inpatient multicomponent rehabilitation program (depending on which invitation was sent) or an outpatient cognitive behavioral therapy group comparative program. The Long program consists of 3 ½ weeks with full rehabilitation days. The Short program consists of 4 + 4 full days, separated by two weeks, in which a workplace visit will be performed if desirable. Three areas of rehabilitation are targeted: mental training, physical training and work-related problem solving. The primary outcome is number of sick leave days. Secondary outcomes include time until full sustainable return to work, health related quality of life, health related behavior, functional status, somatic and mental health, and perceptions of work. In addition, health economic evaluation will be performed, and the implementation of the interventions, expectations and experiences of users and service providers will be investigated with different qualitative methods. TRIAL REGISTRATION: ClinicalTrials.gov: NCT01926574.

Effects of replacing free weights with elastic band resistance in squats on trunk muscle activation.

The purpose of this study was to assess the effects of adding elastic bands to free-weight squats on the neuromuscular activation of core muscles. Twenty-five resistance trained women with 4.6 ± 2.1 years of resistance training experience participated in the study. In randomized order, the participants performed 6 repetition maximum in free-weight squats, with and without elastic bands (i.e., matched relative intensity between exercises). During free-weight squats with elastic bands, some of the free weights were replaced with 2 elastic bands attached to the lowest part of the squat rack. Surface electromyography (EMG) activity was measured from the erector spinae, external oblique, and rectus abdominis, whereas a linear encoder measured the vertical displacement. The EMG activities were compared between the 2 lifting modalities for the whole repetition and separately for the eccentric, concentric, and upper and lower eccentric and concentric phases. In the upper (greatest stretch of the elastic band), middle, and lower positions in squats with elastic bands, the resistance values were approximately 117, 105, and 93% of the free weight-only trial. Similar EMG activities were observed for the 2 lifting modalities for the erector spinae (p = 0.112-0.782), external oblique (p = 0.225-0.977), and rectus abdominis (p = 0.315-0.729) in all analyzed phases. In conclusion, there were no effects on the muscle activity of trunk muscles of substituting some resistance from free weights with elastic bands in the free-weight squat.

Effects of grip width on muscle strength and activation in the lat pull-down.

The lat pull-down is one of the most popular compound back exercises. Still, it is a general belief that a wider grip activates the latissimus dorsi more than a narrow one, but without any broad scientific support. The aim of the study was to compare 6 repetition maximum (6RM) load and electromyographic (EMG) activity in the lat pull-down using 3 different pronated grip widths. Fifteen men performed 6RM in the lat pull-down with narrow, medium, and wide grips (1, 1.5, and 2 times the biacromial distance) in a randomized and counterbalanced order. The 6RM strengths with narrow (80.3 ± 7.2 kg) and medium grip (80 ± 7.1 kg) were higher than wide grip (77.3 ± 6.3 kg; p = 0.02). There was similar EMG activation between grip widths for latissimus, trapezius, or infraspinatus, but a tendency for biceps brachii activation to be greater for medium vs. narrow (p = 0.09), when the entire movement was analyzed. Analyzing the concentric phase separately revealed greater biceps brachii activation using the medium vs. narrow grip (p = 0.03). In the eccentric phase, there was greater activation using wide vs. narrow grip for latissimus and infraspinatus (p ≤ 0.04), and tendencies for medium greater than narrow for latissimus, and medium greater than wide for biceps (both p = 0.08), was observed. Collectively, a medium grip may have some minor advantages over small and wide grips; however, athletes and others engaged in resistance training can generally expect similar muscle activation which in turn should result in similar hypertrophy gains with a grip width that is 1-2 times the biacromial distance.

Effects of BOSU ball(s) during sit-ups with body weight and added resistance on core muscle activation.

The objective of this study was to assess the electromyographic activity of the rectus abdominis (upper and lower part) and external oblique during sit-ups performed on BOSU ball(s). Twenty-four men participated in a familiarization session, and in the next session, they performed the experimental tests in randomized order. The sit-ups were performed with 10 repetitions with body weight and with 10 repetition maximum (10RM) using elastic bands as external resistance under 4 different conditions: (a) on a stable surface, (b) with the BOSU ball under their feet (dome side down, lower-body instability), (c) BOSU ball under the low back (dome side up, upper-body instability), and (d) with BOSU balls under both feet and the low back (dual instability). The feet were not attached to the surface. We observed that with body weight, external oblique activation was decreased by upper-body instability and dual instability by 22-24% (p = 0.002-0.006), whereas the rectus abdominis was not affected by the surface. Using 10RM loads, the upper and lower rectus abdominis activities were increased by upper body and dual instability by 21-24% compared with that for a stable surface (P ≤ 0.001-0.036). Further, lower-body instability did not affect muscle activities significantly with either load for any condition. Hence, BOSU balls under the low back can increase and decrease abdominal muscle activation depending on the load, whereas placing a BOSU ball under the feet with the dome side down had little impact.

Maximal strength training improves work economy, rate of force development and maximal strength more than conventional strength training.

This study compared maximal strength training (MST) with equal training volume (kg × sets × repetitions) of conventional strength training (CON) primarily with regard to work economy, and second one repetition maximum (1RM) and rate of force development (RFD) of single leg knee extension. In an intra-individual design, one leg was randomized to knee-extension MST (4 or 5RM) and the other leg to CON (3 × 10RM) three times per week for 8 weeks. MST was performed with maximal concentric mobilization of force while CON was performed with moderate velocity. Eight untrained or moderately trained men (26 ± 1 years) completed the study. The improvement in gross work economy was -0.10 ± 0.08 L min(-1) larger after MST (P = 0.011, between groups). From pre- to post-test the MST and CON improved net work economy with 31 % (P < 0.001) and 18 % (P = 0.01), respectively. Compared with CON, the improvement in 1RM and dynamic RFD was 13.7 ± 8.4 kg (P = 0.002) and 587 ± 679 N s(-1) (P = 0.044) larger after MST, whereas isometric RFD was of borderline significance 3,028 ± 3,674 N s(-1) (P = 0.053). From pre- to post-test, MST improved 1RM and isometric RFD with 50 % (P < 0.001) and 155 % (P < 0.001), respectively whereas CON improved 1RM and isometric RFD with 35 % (P < 0.001) and 83 % (P = 0.028), respectively. Anthropometric measures of quadriceps femoris muscle mass and peak oxygen uptake did not change. In conclusion, 8 weeks of MST was more effective than CON for improving work economy, 1RM and RFD in untrained and moderately trained men. The advantageous effect of MST to improve work economy could be due to larger improvements in 1RM and RFD.

Muscle force output and electromyographic activity in squats with various unstable surfaces.

The purpose of the study was to compare force output and muscle activity of leg and trunk muscles in isometric squats executed on stable surface (i.e., floor), power board, BOSU ball, and balance cone. Fifteen healthy men (23.3 ± 2.7 years, mass: 80.5 ± 8.5 kg, height: 1.81 ± 0.09 m) volunteered. The force output and electromyographic (EMG) activities of the rectus femoris, vastus medialis, vastus lateralis, biceps femoris, soleus, rectus abdominis, oblique external, and erector spinae were assessed. The order of the surfaces was randomized. One familiarization session was executed before the experimental test. Compared with stable surface (749 ± 222 N), the force output using power board was similar (-7%, p = 0.320) but lower for BOSU ball (-19%, p = 0.003) and balance cone (-24%, p ≤ 0.001). The force output using BOSU ball and balance cone was approximately 13% (p = 0.037) and approximately 18% (p = 0.001) less than the power board. There were similar EMG activities between the surfaces in all muscles except for rectus femoris, in which stable squat provided greater EMG activity than did the other exercises (p = 0.004-0.030). Lower EMG activity was observed in the rectus femoris using balance cone compared with the BOSU ball (p = 0.030). In conclusion, increasing the instability of the surface during maximum effort isometric squats usually maintains the muscle activity of lower-limb and superficial trunk muscles although the force output is reduced. This suggests that unstable surfaces in the squat may be beneficial in rehabilitation and as a part of periodized training programs, because similar muscle activity can be achieved with reduced loads.

Effects of body position and loading modality on muscle activity and strength in shoulder presses.

Little is known about the effect of performing upper-body resistance exercises with dumbbells versus barbells and standing versus seated. Therefore, this study sought to compare electromyogram activity (EMG) and one-repetition maximum (1-RM) in barbell and dumbbell shoulder presses performed seated and standing. Fifteen healthy men volunteered for 1-RM and EMG testing with a load corresponding to 80% of the 1-RM. Electromyogram activity was measured in the anterior, medial, and posterior deltoids and biceps and triceps brachii. The following EMG differences or trends were observed: For deltoid anterior: ~11% lower for seated barbell versus dumbbell (p = 0.038), ~15% lower in standing barbell versus dumbbell (p < 0.001), ~8% lower for seated versus standing dumbbells (p = 0.070); For medial deltoid, ~7% lower for standing barbell versus dumbbells (p = 0.050), ~7% lower for seated versus standing barbell (p = 0.062), 15% lower for seated versus standing dumbbell (p = 0.008); For posterior deltoid: ~25% lower for seated versus standing barbell (p < 0.001), ~24% lower for seated versus standing dumbbells (p = 0.002); For biceps, ~33% greater for seated barbell versus dumbbells (p = 0.002), 16% greater for standing barbell versus dumbbell (p = 0.074), ~23% lower for seated versus standing dumbbells (p < 0.001); For triceps, ~39% greater for standing barbell versus dumbbells (p < 0.001), ~20% lower for seated versus standing barbell (p = 0.094). 1-RM strength for standing dumbbells was ~7% lower than standing barbell (p = 0.002) and ~10% lower than seated dumbbells (p < 0.001). In conclusion, the exercise with the greatest stability requirement (standing and dumbbells) demonstrated the highest neuromuscular activity of the deltoid muscles, although this was the exercise with the lowest 1-RM strength.

Electromyographic activity and 6RM strength in bench press on stable and unstable surfaces.

The purpose of the study was to compare 6-repetition maximum (6RM) loads and muscle activity in bench press on 3 surfaces, namely, stable bench, balance cushion, and Swiss ball. Sixteen healthy, resistance-trained men (age 22.5 ± 2.0 years, stature 1.82 ± 6.6 m, and body mass 82.0 ± 7.8 kg) volunteered for 3 habituation/strength testing sessions and 1 experimental session. In randomized order on the 3 surfaces, 6RM strength and electromyographic activity of pectoralis major, deltoid anterior, biceps brachii, triceps brachii, rectus abdominis, oblique external and erector spinae were assessed. Relative to stable bench, the 6RM strength was approximately 93% for balance cushion (p ≤ 0.001) and approximately 92% for Swiss ball (p = 0.008); the pectoralis major electromyographic (EMG) activity was approximately 90% using the balance cushion (p = 0.080) and approximately 81% using Swiss ball (p = 0.006); the triceps EMG was approximately 79% using the balance cushion (p = 0.028) and approximately 69% using the Swiss ball (p = 0.002). Relative to balance cushion, the EMG activity in pectoralis, triceps, and erector spinae using Swiss ball was approximately 89% (p = 0.016), approximately 88% (p = 0.014) and approximately 80% (p = 0.020), respectively. In rectus abdominis, the EMG activity relative to Swiss ball was approximately 69% using stable bench (p = 0.042) and approximately 65% using the balance cushion (p = 0.046). Similar EMG activities between stable and unstable surfaces were observed for deltoid anterior, biceps brachii, and oblique external. In conclusion, stable bench press had greater 6RM strength and triceps and pectoralis EMG activity compared with the unstable surfaces. These findings have implications for athletic training and rehabilitation, because they demonstrate an inferior effect of unstable surfaces on muscle activation of prime movers and strength in bench press. If an unstable surface in bench press is desirable, a balance cushion should be chosen instead of a Swiss ball.

A comparison of muscle activity and 1-RM strength of three chest-press exercises with different stability requirements.

The purpose of this study was to compare one-repetition maximum (1-RM) and muscle activity in three chest-press exercises with different stability requirements (Smith machine, barbell, and dumbbells). Twelve healthy, resistance-trained males (age 22.7 ± 1.7 years, body mass 78.6 ± 7.6 kg, stature 1.80 ± 0.06 m) were tested for 1-RM of the three chest-press exercises in counterbalanced order with 3-5 days of rest between the exercises. One-repetition maximum and electromyographic activity of the pectoralis major, deltoid anterior, biceps, and triceps brachii were recorded in the exercises. The dumbbell load was 14% less than that for the Smith machine (P ≤ 0.001, effect size [ES] = 1.05) and 17% less than that for the barbell (P ≤ 0.001, ES = 1.11). The barbell load was ∼3% higher than that for the Smith machine (P = 0.016, ES = 0.18). Electrical activity in the pectoralis major and anterior deltoid did not differ during the lifts. Electrical activity in the biceps brachii increased with stability requirements (i.e. Smith machine

No Time to Lift? Designing Time-Efficient Training Programs for Strength and Hypertrophy: A Narrative Review.

Lack of time is among the more commonly reported barriers for abstention from exercise programs. The aim of this review was to determine how strength training can be most effectively carried out in a time-efficient manner by critically evaluating research on acute training variables, advanced training techniques, and the need for warm-up and stretching. When programming strength training for optimum time-efficiency we recommend prioritizing bilateral, multi-joint exercises that include full dynamic movements (i.e. both eccentric and concentric muscle actions), and to perform a minimum of one leg pressing exercise (e.g. squats), one upper-body pulling exercise (e.g. pull-up) and one upper-body pushing exercise (e.g. bench press). Exercises can be performed with machines and/or free weights based on training goals, availability, and personal preferences. Weekly training volume is more important than training frequency and we recommend performing a minimum of 4 weekly sets per muscle group using a 6-15 RM loading range (15-40 repetitions can be used if training is performed to volitional failure). Advanced training techniques, such as supersets, drop sets and rest-pause training roughly halves training time compared to traditional training, while maintaining training volume. However, these methods are probably better at inducing hypertrophy than muscular strength, and more research is needed on longitudinal training effects. Finally, we advise restricting the warm-up to exercise-specific warm-ups, and only prioritize stretching if the goal of training is to increase flexibility. This review shows how acute training variables can be manipulated, and how specific training techniques can be used to optimize the training response: time ratio in regard to improvements in strength and hypertrophy.

Return-to-work self-efficacy after occupational rehabilitation for musculoskeletal and common mental health disorders: Secondary outcomes of a randomized clinical trial.

OBJECTIVE: To assess the effects of adding a workplace intervention to inpatient occupational rehabilitation on return-to-work self-efficacy, and whether changes in return-to-work self-efficacy were associated with future work outcomes. DESIGN: Randomized clinical trial. SUBJECTS: Individuals aged 1860 years, sick-listed 212 months were randomized to multimodal inpatient rehabilitation with (n?=?88) or without (n?=?87) a workplace intervention. METHODS: Between-group differences for 4 months follow-up were assessed using linear mixed models. Associations between self-efficacy scores and future sickness absence days during 12 months of follow-up were assessed by linear regression. RESULTS: There were no statistically significant between-group differences in self-efficacy during follow-up. Participants with high or medium self-efficacy scores at the end of rehabilitation had fewer sickness absence days during follow-up compared with participants with low scores. Participants with consistently high scores or an increasing score throughout the programme showed fewer sickness absence days than those with reduced or consistently low scores. CONCLUSION: Receiving an added workplace intervention did not increase return-to-work self-efficacy more than standard inpatient occupational rehabilitation alone. High scores and a positive development in return-to-work self-efficacy were associated with higher work participation. This suggests that return-to-work self-efficacy could be an important factor to consider in the return-to-work process.

No effect of prior caffeine ingestion on neuromuscular recovery after maximal fatiguing contractions.

The purpose of this study was to test the hypothesis that prior caffeine ingestion would enhance neural recovery after isometric fatiguing maximal intermittent plantar flexions, and thus would enhance the recovery of voluntary muscle strength. After a familiarisation session, 13 males randomly participated in two experimental trials where they ingested either caffeine (approximately 6 mg/kg) or identical placebo pills 1 h prior to testing. Subjects were tested for electromyogram (EMG) activity and evoked V-waves in the soleus and gastrocnemius medialis muscles. These measurements were obtained during brief plantar flexion maximum voluntary isometric contractions (MVICs), and normalised by the superimposed maximal M-wave (EMG/M(SUP) and V/M(SUP), respectively), before and after (20 s, 10 min and 20 min) a fatigue protocol (seven 25 s MVICs, 5 s rest). There were no effects (P > 0.05) of caffeine ingestion on EMG/M(SUP), V/M(SUP), MVIC or M(SUP). The central neural modulation (EMG/M(SUP) and V/M(SUP)) and voluntary strength changes followed a similar time-course with a substantial reduction 20 s post-fatigue and a gradual return towards baseline values.

Enhanced neural drive after maximal strength training in multiple sclerosis patients.

Multiple sclerosis (MS) patients suffer from impaired muscle activation and lower limb strength. Strength training enhances muscle activation and muscle strength, but neural adaptations to strength training remain unexplored in MS patients. The hypothesis was that maximal strength training (MST) using high loads and few repetitions would improve central neural drive and thus strength capacity of MS patients. 14 MS patients staying at a national MS rehabilitation center were randomly assigned to a MST group or a control group (CG). Both groups received "today's treatment". In addition, the MST group trained 4 x 4 repetitions of unilateral dynamic leg press and plantar flexion 5 days a week for 3 weeks. Neural adaptations of the soleus muscle were assessed by surface electromyography (EMG) activity, and by superimposed H-reflexes and V-waves obtained during maximum voluntary isometric plantar flexor contractions (MVCs). H-reflexes and V-waves were normalized by the M-wave (H(SUP)/M(SUP), V/M(SUP), respectively). In the MST group, MVC increased by 20 +/- 9% (P < 0.05). Soleus EMG activity and V/M(SUP) ratio increased by 40 and 55%, respectively, in the MST group compared to the CG (P