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Related Experiment Video

Updated: May 23, 2026

Measurement of Spatial Stability in Precision Grip

Measurement of Spatial Stability in Precision Grip

Published on: June 4, 2020

Force, frequency and gripping alter upper extremity muscle activity during a cyclic push task.

Peter J Keir¹, Melissa M Brown

¹McMaster Occupational Biomechanics Laboratory, Department of Kinesiology, McMaster University, Hamilton, ON, Canada. pjkeir@mcmaster.ca

|April 18, 2012

Summary

Workload, combining push force and frequency, significantly impacts upper extremity muscle activity. Concurrent gripping can override these effects, highlighting complex muscle loading in workplace disorders.

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Area of Science:

Occupational Health
Biomechanics
Ergonomics

Background:

Repetitive tasks, high forces, and gripping are key factors in developing upper extremity work-related musculoskeletal disorders.
Understanding the interplay of these factors is crucial for preventing workplace injuries.

Purpose of the Study:

To systematically investigate the effects of push load and task frequency on upper extremity muscle activity.
To examine how concurrent gripping influences muscle responses during pushing tasks.

Main Methods:

A controlled study involving 20 participants (10 men, 10 women) performing a cyclic bimanual pushing task.
Varied push loads (1, 2, 4 kg), frequencies (4, 8, 16/min), and grip conditions (no grip, 30% max grip force) in a randomized order.
Electromyography was used to measure muscle activity in the upper arm and shoulder complex, and forearm.

Main Results:

Muscle activity in the upper arm and shoulder complex was influenced by both push load and frequency, often interacting significantly.
Workload (force × frequency) provided a better description of muscle response in the upper arm and shoulder.
Forearm muscle activity was less affected by push load but was significantly influenced by the addition of a submaximal grip, primarily reflecting frequency and grip exertion.

Conclusions:

Upper extremity muscle activity exhibits a complex response to workload, which can be modulated by the presence of a grip.
The findings provide physiological insights into muscular loading during pushing tasks, relevant for understanding and mitigating various workplace disorders.