Muscular fatigue measurements for push‐down tasks in ground demolitions

Abstract

Demolition hammering tasks are physically demanding tasks that could cause muscle fatigue and musculoskeletal disorders. Electromyography (EMG) data have been adopted to assess levels of muscular activity and onset of muscular fatigue for both industrial tasks and physical activities. An experiment simulating a manual demolition task on the ground was performed on 23 healthy male participants. The objectives were to test the hypotheses that the handle height and the force applied to affect the EMG amplitude, the increase of the EMG amplitude, and the decline of the mean power frequency (MPF) of the EMG for performing the tasks. This study also aimed at finding the most fatigued muscles which dominate the end of the sustained push-down tasks in ground demolitions. The results showed that the EMG amplitude required to perform the tasks was significantly affected by the handle height and force applied. Significant increases in EMG amplitude and decreases in MPF were found. Bicep brachii, tricep brachii, and pectoralis major muscles were the most fatigued muscles that dominated the termination of the tasks. Pushing with body leaning forward to utilize partial body weight was less fatiguing than the other two postures. Elbow flexion is undesirable and should be avoided when performing such tasks.

Modeling and Validation of Fatigue and Recovery of Muscles for Manual Demolition Tasks

“…In the muscle fatigue experiment, the load significantly affected MET ( p < 0.0001). This was consistent with the findings in the literature [ 12 , 19 , 33 ]. It was anticipated that the weight of the tool could have an effect on the MET.…”

“…Both the MET and MS before and after the test were recorded. The MS before the test was the maximum voluntary contraction ( MVC ) [ 12 , 23 , 33 , 40 ], and the MS after the push was recorded as MS 0 . After the trial, the CR-10 was recorded based on Borg CR-10 [ 34 ] and was denoted as CR-10 0 .…”

“…They may lead to muscle fatigue and risk of WMSDs due to heavy load, awkward posture, length of work time, poor working environment, and tool vibration [ 29 , 30 ]. Existing research on muscle fatigue issues associated with manual demolition tasks have focused on vibration transmission [ 31 , 32 ], MS change [ 33 ] under different operating conditions. However, the development of muscle fatigue and progress of fatigue recovery for these tasks remain unclear.…”

“…The decline of muscle strength, subjective rating of muscle fatigue, and MET have been adopted to indicate the development of muscle fatigue [ 12 , 18 , 19 , 33 ]. This study aims to explore the development of muscle fatigue and the progress of muscle recovery for manual demolition tasks.…”

Effects of Pause Design on the Decline in Pulling Effort and the Evaluation of Perceived Effort in Pulling Tasks

“…Assessments of muscular fatigue for pushing and pulling tasks are essential to quantify the risk of MSDs. Pushing/pulling task-induced muscular fatigue may be assessed via developing empirical models [15][16][17] and studying the decrease of muscular strength [18], the electromyogram activities of muscles involved [19,20], the subjective responses of muscle fatigue [21], the endurance time [18,20,22], and metabolic responses [23,24] of the participants performing the tasks under specific conditions.…”