Mohd Farooq

Effect of shoulder rotation, upper arm rotation and elbow flexion in a repetitive gripping task.

OBJECTIVES To investigate the effects of upper limb postures on discomfort score for repetitive gripping task. PARTICIPANTS Eighteen right handed male participants volunteered in the experimental investigations. METHOD The present study was divided into two experiments. A Full factorial design of 2 (Two shoulder rotation angles) × 3 (Three elbow flexion angles) × 3 (Three upper arm rotation angles) was used. The effect of postures on MVC grip strength, Grip endurance and on discomfort score, for a repetitive task at 150 N ± 5 N with exertions 15 per minute was recorded. In a supplementary experiment, the EMG recordings were also taken for validating the effect of elbow flexion angle. RESULTS ANOVA showed that the main effects of postures were not significant on MVC grip, except elbow flexion (p < 0.001). The endurance time was also significant (p=0.0100) for elbow flexion and there was no effect of other postures. The second experiment showed that the effect of shoulder rotation, elbow flexion and forearm rotation was significant (p <0.001) on discomfort score. The EMG activity of the muscles also showed that FDP and ECRB muscles had maximum reduction in median frequencies of the EMG signals of the respective muscles at 45° elbow flexion angle. CONCLUSIONS The main effects of elbow flexion angle, shoulder rotation and forearm rotation were significant on discomfort score for the repetitive gripping task of the present study.

Effect of elbow flexion, forearm rotation and upper arm abduction on MVC grip and grip endurance time.

Abstract This experiment was designed to know the effect of upper limb postural deviations on grip strength and grip endurance time. A full factorial design of experiment, i.e., 3 (0°, 45°, 90° abduction angles of upper arm) × 3 (45°, 90°, 135° angles of elbow flexion) ×3 (0°, -60° prone, +60° supine angles of forearm rotation) was used to find the effect of 27 combinations of postures on maximum voluntary contraction (MVC) grip strength and grip endurance time. The results showed that none of the main factors were significant on MVC grip, although there was a change in MVC grip. Grip endurance time significantly decreased with an increase in upper arm abduction. Also, grip endurance significantly increased with the elbow flexion angle and decreased with forearm rotation from neutral. These data will help designers and engineers to improve the workplace and tools to reduce the risk of injuries.

Effect of whole-body vibration on neuromuscular performance: A literature review

BACKGROUND Whole-body vibration (WBV) is a neuromuscular training method that has recently received popularity in health and fitness centers, as an additional or substitute method to conventional training and therapy, in order to improve muscle strength and power. OBJECTIVE The purpose of this review is to critically observe the effect of WBV training on neuromuscular performance in view of its ability to enhance the muscles strength, power, and flexibility; and also to investigate the influence of the different vibration characteristics (viz., method of application of vibration, frequency, and amplitude) and exercise protocols on the effect of this training. METHOD For this review 24 studies or articles were examined, and based on exclusion and inclusion criteria, 5 studies were finally selected; and an attempt was made to uncover the factors influencing the improvement in neuromuscular performance as a result of WBV intervention. During the review, it was considered to include and discuss as many characteristics as possible, such as, knee extension, knee flexion, counter movement jump (CMJ), squat exercise, and jumping height (JH). RESULT Whole-body vibration, along with additional exercise training, has a potential to induce substantial improvement in neuromuscular performance. CONCLUSION Whole-body vibration can bring about improvement in muscles strength, power, and flexibility. The main factors associated with the improvement in muscles performance are range of amplitude and frequency, type of vibration and its method of application, training intensity, exercise protocol, and the characteristics of the participants.