Study of the effect of simultaneous exposure to noise and heat stress on the activity level of biceps and flexor muscles

Harmful factors in the workplace such as noise and heat stress can have adverse effects on muscle activity. This study was performed to investigate the effect of simultaneous exposure to noise and heat stress on the activity level of biceps and flexor muscles.

This experimental study was performed on 24 male students in laboratory conditions. Participants in three groups exposure to SPL of 75, 85 and 95 dBA and WBGT =22, 30 and 35°C randomly. During light manual activity, the activity level of biceps and flexor muscles was measured in a sitting manner using surface electromyography. Normalized RMS (Root Mean Square) of muscles was used to compare the level of muscle activity in different conditions. ANOVA test was used to examine the relationship between variables.

The mean (SD) age of the study participants was 21±1.6 years. Based on the muscle activity WBGT=30°C and SPL=85 dB were defined as border points in changes of biceps activity. The highest and lowest levels of flexor muscle activity were observed at SPL of 75 and 95 dB, respectively. The interaction between noise and heat stress exposure show that exposure to both factors causes significant changes in muscle activity levels (P.value<0.05).

Exposure to noise and heat stress in the workplace affects the function of the biceps and flexors muscles. To more accurately determine the effects of noise exposure and heat stress on muscle activity, further studies are recommended.