The purpose of this study was to investigate the effects of different types and sizes of gloves on external grip force and muscle activity. Twenty-one male and seven female volunteers served as subjects. Each subject performed two maximum voluntary grip contractions while wearing each of the 10 glove types. Results indicated significant differences in the effects of different glove types on the peak force, ratio of peak force to normalized flexor muscle EMG activity, and the ratio of peak force to coactivity.

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This study evaluated spinal loads associated with lifting and hanging heavy mining cable in a variety of postures. This electrical cable can weigh up to 10 kg per metre and is often lifted in restricted spaces in underground coal mines. Seven male subjects performed eight cable lifting and hanging tasks, while trunk kinematic data and trunk muscle electromyograms (EMGs) were obtained. The eight tasks were combinations of four postures (standing, stooping, kneeling on one knee, or kneeling on both knees) and two levels of cable load (0 N or 100 N load added to the existing cable weight). An EMG-assisted model was used to calculate forces and moments acting on the lumbar spine. A two-way split-plot ANOVA showed that increased load (p < 0.05) and changes in lifting posture (p < 0.05) independently affected trunk muscle recruitment and spinal loading. The increase in cable load resulted in higher EMG activity of all trunk muscles and increased axial and lateral bending moments on the spine (p < 0.05). Changes in posture caused more selective adjustments in muscle recruitment and affected the sagittal plane moment (p < 0.05). Despite the more selective nature of trunk EMG changes due to posture, the magnitude of changes in spinal loading was often quite dramatic. However, average compression values exceeded 3400 N for all cable lifting tasks.

Localized muscle fatigue in the back, with a resulting decrease in muscle force production, may increase risk of injury. Numerous methods have been used to assess fatigue in the back during materials handling, but many of these methods remain questionable as to what they are actually measuring. The goal of this study was to compare five different methods for measuring fatigue resulting from dynamic lifting, and to determine which methods correlate best with fatigue. Eight subjects performed sagittally symmetric lifts at a frequency of 12 lifts per minute for 60-minutes. Throughout the experiment, VO2, heart rate, local muscle oxygenation measured by Near Infrared Spectroscopy (NIRS), and subjective feedback was recorded. The whole body measures, VO2 and heart rate, were weakly correlated with the localized measures of NIRS and spectral analysis. Few of these correlations were significant, and none showed strong relationships. The subjective measures correlated well with NIRS. The results of this study suggest current measures of fatigue may not assess the risk of fatigue to a particular muscle. It is important that more comparative studies are done to better the understanding of fatigue and what is being measured by common measures of fatigue. Additional studies should be done, particularly for the more quantitative, localized, measures such as NIRS.