PurposeEpidemiological research has identified women to be more susceptible to developing neck–shoulder musculoskeletal disorders when performing low-force, repetitive work tasks. Whether this is attributable to gender differences in fatigability and motor control is currently unclear. This study investigated the extent to which women differ from men in fatigability and motor control while performing a short-cycle repetitive task.Methods113 healthy young adults (58 women, 55 men) performed a standardized repetitive pointing task. The task was terminated when the subject’s perceived exertion reached 8 on the Borg scale. The time to task termination, and changes in means and cycle-to-cycle variabilities of surface electromyography signals from start to end of the task, were compared between women and men, for the upper trapezius, anterior deltoid, biceps and triceps muscles.ResultsWomen and men terminated the task after 6.5 (SD 3.75) and 7 (SD 4) min on average (p > 0.05). All four muscles showed an increase of 25–35 % in average muscle activity with fatigue (no significant sex differences). However, men exhibited a higher increase than women in trapezius muscle variability with fatigue (31 vs. 7 %; p < 0.05), and a decrease in biceps muscle variability where women had an increase (−23 vs. 12 %; p < 0.05).ConclusionsOur results suggest that women and men may not differ in the ability to perform repetitive tasks at low-to-moderate force levels. However, differences in motor control strategies employed in task performance may explain gender differences in susceptibility to developing musculoskeletal disorders when performing repetitive work for prolonged periods in occupational life.

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The overall aim of this study was to measure the physiological responses of firefighters from a single fire service during simulated functional firefighting tasks and to establish the relationship between physical fitness parameters and task performance. 46 males and 3 females firefighters were recruited. Firefighters' aerobic capacity levels were estimated using the Modified Canadian Aerobic Fitness Test (mCAFT). Grip strength levels, as a measure of upper body strength levels, were assessed using a calibrated J-Tech dynamometer. The National Institute for Occupational Safety and Health (NIOSH) protocol for the static floor lifting test was used to quantify lower body strength levels. Firefighters then performed two simulated tasks: a hose drag task and a stair climb with a high-rise pack tasks. Pearson's correlation coefficients (r) were calculated between firefighters' physical fitness parameters and task completion times. Two separate multivariable enter regression analyses were carried out to determine the predictive abilities of age, sex, muscle strength, and resting heart rate on task completion times. Our results displayed that near maximal heart rates of ≥88% of heart rate maximum were recorded during the two tasks. Correlation (r) ranged from −0.30 to 0.20. For the hose drag task, cardiorespiratory fitness and right grip strength (kg) demonstrated the highest correlations of −0.30 and −0.25, respectively. In predicting hose drag completion times, age and right grip strength scores were shown to be the statistically significant (p < 0.05) independent variables in our regression model. In predicting stair climb completion times, age and NIOSH scores were shown to be the statistically significant (p < 0.05) independent variables in our regression model. In conclusion, the hose drag and stair climb tasks were identified as physiological demanding tasks. Age, sex, resting heart rate, and upper body/lower body strength levels had similar predictive values on hose drag and stair climb completion times.

Introduction: The objective of this cross-sectional study is to describe the prevalence and severity of self-reported musculoskeletal disorders (MSDs) in firefighters and how these vary by demographics and length of service (LOS). Methods: A cohort of 294 active-duty firefighters completed a body diagram to indicate the location and pain intensity of their MSK complaints. Where painful sites were indicated, they completed the relevant region-specific self-report disability measure – Neck Disability Index (NDI), Roland Morris Disability Questionnaire (RMDQ), Lower Extremity Functional Scale (LEFS), or the Short Form of Disabilities of the Arm, Shoulder and Hand (QuickDASH) – to quantify severity. Prevalence was determined from the body diagrams and severity from the site-specific self-report questionnaires. Differences in MSK severity based on demographics or LOS were determined using ANOVA. Results: The 294 active-duty firefighters had a mean age of 42.6 (SD 9.7) years and mean duration of service of 15.1 (SD 10.1) years. The prevalence of neck, back, upper-limb, and lower-limb complaints was 20%, 33%, 44%, and 45% respectively. Firefighters 42 years or older reported significantly more severe lower-extremity disability (median (IQR) LEFS: 71 (65, 77) vs. 75 (69.5, 78.5), p=0.03) and more severe back disability (median (IQR) RMDQ: 2 (1, 3) vs. 1 (0, 2), p=0.04). Firefighters with 15 years or more of firefighting service reported significantly more severe lower extremity disability (median (IQR) LEFS: 71 (64, 77) vs. 76 (70, 79), p=0.0005). Firefighters reporting >1 MSDs were significantly older than firefighters reporting no MSD ( F(5,285)=3.3, p=0.002). Discussion: The rate of MSDs is high in firefighters, and their severity is elevated with greater age and LOS, suggesting cumulative exposures/injuries and highlighting the need for ongoing assessment of the musculoskeletal system and interventions to reduce injury throughout firefighters' careers.