Intermittently increased repetitive work intensity and neuromuscular function in the cold

Area of Science:

• Exercise Physiology
• Environmental Physiology
• Neuromuscular Science

Background:

• Cold exposure can impair neuromuscular function, leading to reduced efficiency and increased muscle strain.
• Monotonous, low-intensity workloads in cold environments exacerbate these negative effects.

Purpose of the Study:

• To investigate if intermittently increasing workload can mitigate cold-induced neuromuscular dysfunction.
• To assess the impact of workload variation on muscle strain, co-activation, EMG gaps, and neuromuscular efficiency in cold.

Main Methods:

• Participants performed wrist flexion/extension tasks at 21°C (TN) and 4°C.
• In the cold, one condition maintained a constant 10% maximal voluntary contraction (MVC) workload (C(10)).
• Another cold condition (C(50)) involved increasing the workload to 50% MVC every four minutes.

Main Results:

• At 4°C with a constant low workload (C(10)), muscle strain and co-activation were highest, while EMG gaps and neuromuscular efficiency were lowest.
• Intermittently increasing workload in the cold (C(50)) significantly reduced muscle strain and co-activation (p<0.05).
• The C(50) condition also showed a trend towards increased EMG gaps and improved neuromuscular efficiency compared to C(10).

Conclusions:

• Breaking monotonous work cycles by intermittently increasing workload can partially restore neuromuscular function impaired by cold.
• Varying workload intensity is a potential strategy to counteract the detrimental effects of cold on neuromuscular performance.