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[Localized muscular load to different work patterns and heat loads during handgrip]
1Department of Ergonomics, Graduate School of Science and Technology, Chiba University.
Summary
Higher temperatures increase forearm muscle fatigue and alter blood flow during isometric handgrip exercises. Perceived fatigue and blood pressure were minimally affected by heat.
Area of Science:
- Exercise Physiology
- Human Physiology
- Muscle Physiology
Context:
- Isometric handgrip contractions are common in occupational and athletic settings.
- Understanding physiological responses to varying exercise durations and heat stress is crucial for performance and safety.
- Previous research has explored fatigue mechanisms but often without controlled heat loads.
Purpose:
- To investigate the physiological responses and perceived fatigue during isometric handgrip under different work patterns and heat conditions.
- To analyze the impact of heat stress (25°C vs. 40°C) on electromyogram (EMG), heart rate (HR), mean blood pressure (MBP), and forearm blood flow.
- To determine the relationship between perceived fatigue and physiological markers.
Summary:
- Eight healthy men performed continuous and intermittent isometric handgrip exercises at 10% MVC under 25°C and 40°C heat loads.
- Localized muscle fatigue was observed, with higher EMG mean frequency at 40°C.
- Forearm blood flow during relaxation (FBFR) was lower than during contraction (FBFC) at 40°C, while perceived fatigue and MBP showed minimal heat influence.
- Perceived fatigue correlated with HR and MBP.
Impact:
- Findings highlight the impact of heat on muscle fatigue and local blood flow regulation during isometric contractions.
- Provides insights into physiological strain during prolonged handgrip tasks in warm environments.
- Informs strategies for managing fatigue and optimizing performance in heat-exposed occupations or sports.