Fatigue and endurance limits during intermittent overhead work.

The sensitivity of shoulder muscle fatigue to vertical hand location during complex manual force exertions

The effect of maximum voluntary contraction on endurance times for the shoulder girdle

The influence of cycle time on shoulder fatigue responses for a fixed total overhead workload

The endurance time has been reported to be the most sensitive measure of improved exercise capacity in response to a variety of interventions for COPD. The aim of the present study was to determine whether the improvements in quadriceps force and measures obtained from a symptom-limited maximal test contributed to the improvements in endurance time following pulmonary rehabilitation. Fifty-seven consecutive COPD subjects completed a 10-week pulmonary rehabilitation program. The subjects completed a symptom-limited incremental cycle ergometry test and a constant work rate test before and after pulmonary rehabilitation. Peripheral and respiratory muscle strength was also measured. The relationships between the change in endurance time and the changes obtained from the incremental test and muscle strength test were investigated. The endurance time showed the greatest improvement among the exercise capacity indices. The changes in endurance time were significantly correlated to changes in quadriceps force, peak work rate, anaerobic threshold and work efficiency on the incremental load test. In the multiple stepwise regression analysis, changes in quadriceps force and work efficiency measured on the maximal exercise test were selected. These findings suggest that the improvements in endurance time after pulmonary rehabilitation may be explained by increased quadriceps force and improvements in peak work rate and work efficiency.

Background: Age, gender, diet, and body mass index (BMI) are important physiological factors that can affect muscle strength and bone mineral density (BMD). Obesity and osteoporosis are two important and developing public health problems worldwide. Aims and Objectives: This study aims to know the relationship between physiological factors such as age, gender, diet, BMI, and handgrip strength (HGS) on BMD in healthy men and women. Materials and Methods: A total of 198 participants of age 30–70 years were included in the study. BMI was calculated using Quetelet index. Measurement of HGS was done using a handgrip dynamometer following standard methods. HGS max in kg and endurance time (ET) in seconds were recorded. BMD was recorded using bone sonometer, in the distal end of tibia. Results: Age had a weak negative correlation with BMD, HGS max, and ET. BMD had a weak negative correlation with BMI though statistically not significant. BMI among vegetarian (V) and non-vegetarian (NV) group with normal BMI range, occurrence of osteoporosis was higher among vegetarian. In overweight/obese, osteoporosis was higher among NV, though statistically not significant. There was no significant gender difference in BMD between V and NV. ET was statistically significant in NV females. HGS max and ET were higher among NV males but statistically not significant. Conclusion: There is no significant relation between BMI, diet, and HGS max on BMD in V and NV. Hence, we can conclude that well-planned and balanced vegetarian diet is equally nutritious as NV diet for good muscle strength and bone composition.

Development and testing of a wearable passive lower-limb support exoskeleton to support industrial workers

The purpose of this study was to determine the effect of eccentric muscle damage on muscle activation patterns and intermuscular coherence during a fatiguing isometric contraction involving the elbow flexor muscles. Ten young subjects participated in three experimental sessions that involved the performance of maximum voluntary contractions (MVCs), a constant-force task at 30% MVC, and a fatiguing isometric contraction at 30% MVC. The three sessions were performed before, 2 h after and 2 days after eccentric exercise to induce muscle damage in elbow flexor muscles. Task performance was quantified with electromyography (EMG) from the elbow flexor (biceps brachii, brachialis and brachioradialis) and extensor (triceps brachii) muscles, M-wave amplitude of biceps brachii, elbow flexor force fluctuations and endurance time of a fatiguing contraction. Intermuscular coherence during the fatiguing contraction was quantified from the rectified surface EMGs between muscle pairs. Eccentric exercise resulted in several indicators of muscle damage, such as a prolonged decline in muscle strength and an increase in muscle soreness 2 days after exercise. A 29% reduction in endurance time was observed 2 h after eccentric muscle damage, which returned to baseline 2 days later. The reduced endurance time 2 h after muscle damage was accompanied by an increase in EMG-EMG coherence between biceps brachii and brachialis muscles, which was observed at the end of the fatiguing contraction. These findings suggest that eccentric muscle damage produces a decrease in endurance time that is accompanied by an increase in intermuscular coherence in the presence of fatigue.

Inspiratory muscle training: where are we?

Comparison of the efficacy of auricular vagus nerve stimulation and conventional low back rehabilitation in patients with chronic low back pain

BackgroundMusculoskeletal disorders are the leading cause of work-related sick leave and incur substantial socioeconomic costs. With the aging of our society and employees, the problem is exacerbating, and prevention is becoming increasingly important. According to previous studies, exposure to awkward postures, such as overhead work, is associated with musculoskeletal problems.ObjectiveThis study aimed to determine the current prevalence of employees who work in awkward postures, specifically overhead, stratified by age, gender and occupation in the context of the 2018 BIBB/BAuA Employment Survey and to analyze associations between awkward working postures, in particular overhead work, and pain in the shoulder region.MethodThe study is based on secondary data from the German 2018 BIBB/BAuA Employment Survey. We have included 14,327 of the 20,012 employees aged < 67 years who work at least 35 h per week who took part in the survey. The classification of participants in occupational groups is based on the Blossfeld classification. The multivariate analysis was conducted by applying robust Poisson regression models adjusted block by block to obtain the relation between the self-reported frequency of working in awkward postures, in particular overhead work, and the occurrence of arm pain and neck and shoulder pain. Prevalence ratios (PR) are reported as effect estimates.Results12.7% of participants indicated that they are often exposed to awkward postures at work; 5.0% stated they often performed overhead work. The majority of these employees worked in agricultural, unskilled and skilled manual occupations. The crude prevalence is 17.4% for arm pain and 48.4% for neck and shoulder pain. If subjects reported that they often performed overhead work, the risk of arm pain increased by 18% (PR 1.18, CI 1.04–1.34, final model).ConclusionWorking in awkward postures, especially overhead work, is a risk factor for upper extremity musculoskeletal disorders. The development of prevention strategies should focus on the workforce in agricultural, unskilled and skilled manual occupations.

Introduction: Preoperative exercise training can improve the baseline status of patients undergoing open thoracic surgery and therefore improve surgical tolerability and enhance postoperative recovery. The aim of this study was to assess the feasibility and preliminary efficacy of a preoperative exercise-based programme (PEP) in patients undergoing Video-assisted thoracic surgery (VATS) for lung cancer. Materials and Methods: In a randomized, single blinded controlled trial, 20 patients were allocated to receive a PEP consisted of 3 - 5 sessions per week of interval endurance training, strength training with elastic bands and breathing exercises. Exercise capacity (endurance time), muscle strength (Senior Fitness Test) and health-related quality of life (SF-36) were assessed at the beginning and at the end of the training. Results: 10 patients completed the intervention attending a median of 16 sessions. Mean therapeutic delay was 54 days and no adverse events were recorded. There were statistically significant improvements in endurance time measured at 80% of the maximal workload (mean difference +396.6±197.9 seconds, p Conclusions: preoperative exercise training in patients with lung malignancies awaiting VATS is safe and can be achieved without any delay in the surgical management and results effective to improve exercise capacity, muscle strength and physical functioning, which could potentially enhance postoperative recovery.

Respiratory muscle function and exercise capacity in multiple sclerosis.

Objective: This study aims to observe the clinical efficacy of stagnation acupuncture therapy guided by neuromuscular control theory in the treatment of military training-induced chronic nonspecific lower back pain and its effect on serum inflammatory factors. Method: Patients with military training-related chronic nonspecific low back pain were randomly divided into three groups, namely, the stagnation acupuncture group, ordinary acupuncture group, and physiotherapy group, with 30 cases in each group. The physiotherapy group received conventional physical therapy, the ordinary acupuncture group received traditional acupuncture treatment in addition to physical therapy, and the stagnation acupuncture group received stagnation acupuncture treatment in addition to physical therapy. The simplified McGill pain questionnaire scores (including PRI score, PPI score, and VAS score), finger-to-floor distance (FFD), lumbar muscle endurance (flexor endurance time, extensor endurance time), lumbar muscle strength, Japanese Orthopaedic Association (JOA) assessment score, serum inflammatory factors, and clinical efficacy were compared before treatment and after 2 weeks of treatment. Result: The McGill score, finger-to-floor distance (FFD), lumbar muscle endurance (flexor endurance time, extensor endurance time), lumbar muscle strength, JOA score, and serum inflammatory factors in the stagnation acupuncture group were significantly improved compared with those in the ordinary acupuncture group and the physiotherapy group ( P &lt; 0.05), and all three groups were statistically significant compared with before treatment ( P &lt; 0.05). The total effective rate of the stagnation acupuncture group after treatment was 96.67%, which was significantly better than that of the ordinary acupuncture group (90.00%) and physical therapy group (75.76%) ( P &lt; 0.05). Conclusion: Under the guidance of neuromuscular control theory, the stagnation acupuncture therapy focuses on central integration and inflammation regulation as breakthrough points, concentrating on lumbar spine mechanical modulation to treat chronic nonspecific low back pain caused by military training. It has unique advantages such as simplified acupoint selection, mild pain, minimal trauma, and a wide range of effects, making it worthy of clinical promotion and application.

To investigate the effects of inspiratory muscle resistive loading training (IMT) on exercise performance in chronic obstructive pulmonary disease (COPD), 13 patients undergoing standard pulmonary rehabilitation were divided into control (n = 6) and experimental (n = 7) groups. Prior to training, we measured inspiratory muscle strength and endurance, resting pulmonary function, and exercise performance on a bicycle ergometer (a progressive test and an endurance test at two thirds of maximal work load). We then determined their resistive loads for training by measuring their 10-min maximal sustainable resistance. Training by patients in the experimental group involved inspiring against a predetermined resistive load. The control subjects breathed through a sham training tube, so that studies were performed in double-blind fashion. The training consisted of 15-min sessions twice daily for 4 wk. The IMT dramatically improved inspiratory muscle endurance--represented as either sustainable inspiratory pressure (SIP) or endurance time at 60% of maximal inspiratory mouth pressure (Pimmax) at functional residual capacity. The SIP of the trained group increased from 29 +/- 11 to 46 +/- 11% of Pimmax (p less than 0.005). Training slightly increased inspiratory muscle strength (p less than 0.05), as determined by Pimmax. In contrast, resting pulmonary function and performance of both progressive and constant-load exercise remained unchanged. We conclude that 4-wk IMT in a pulmonary rehabilitation setting improves inspiratory muscle endurance in patients with COPD without changing pulmonary function or exercise performance.

Impact of inspiratory muscle training in patients with COPD: what is the evidence?