Reliability analyses and values of isometric shoulder flexion and trunk extension strengths stratified by body mass index.

The main goal of this study was to investigate the reliability of muscle strength across different levels of obesity. A sample of 142 healthy subjects performed maximum voluntary isometric contractions for shoulder flexion and trunk extension on each of four days. Subjects were recruited into one of three groups, non-obese, overweight, or obese, based on body mass index (BMI).

Central and peripheral fatigue development in the shoulder muscle with obesity during an isometric endurance task.

Background: Fatigue increases the likelihood of developing work-related musculoskeletal disorders and injury. Due to the physiological and neuromuscular changes that accompany obesity, it may alter the fatigue development mechanism and exacerbate injury risk. The upper extremities have the highest incidence rates for work-related musculoskeletal disorders.

Testing the efficacy of existing force-endurance models to account for the prevalence of obesity in the workforce.

This study evaluates whether the existing force-endurance relationship models are predictive of endurance time for overweight and obese individuals, and if not, provide revised models that can be applied for ergonomics practice. Data was collected from 141 participants (49 normal weight, 50 overweight, 42 obese) who each performed isometric endurance tasks of hand grip, shoulder flexion, and trunk extension at four levels of relative workload. Subject-specific fatigue rates and a general model of the force-endurance relationship were determined and compared to two fatigue models from the literature.

The effect of obesity on postural stability during a standardized lifting task.

The objective of this study was to assess the effect of obesity on postural stability during a standardized lifting task. Twelve young males, six obese and six non-obese, completed three replications of repeated six lifts (at a rate of six lifts per minutes) at two levels of loads (10% and 25% of capacity) crossed with two levels of orientation (0° and 45° from sagittal plane). Postural stability measures showed that center of pressure sway path and sway area were ∼21% and ∼53% lower with obesity, respectively.