Abstract
Background: Occupational footwear and a prolonged duration of walking have been previously reported to play a role in maintaining postural stability. The purpose of this paper was to analyze the impact of three types of occupational footwear: the steel-toed work boot (ST), the tactical work boot (TB), and the low-top work shoe (LT) on previously unreported lower extremity muscle activity during postural stability tasks. Methods: Electromyography (EMG) muscle activity was measured from four lower extremity muscles (vastus medialis (VM), medial hamstrings (MH), tibialis anterior (TA), and medial gastrocnemius (MG) during maximal voluntary isometric contractions (MVIC) and during a sensory organization test (SOT) every 30 min over a 4 h simulated workload while wearing ST, TB, and LT footwear. The mean MVIC and the mean and percentage MVIC during each SOT condition from each muscle was analyzed individually using a repeated measures ANOVA at an alpha level of 0.05. Results: Significant differences (p < 0.05) were found for maximal exertions, but this was limited to only the time main effect. No significant differences existed for EMG measures during the SOT. Conclusion: The findings suggest that occupational footwear type does not influence lower extremity muscle activity during both MVIC and SOT. Significantly lower muscle activity during maximal exertions over the course of the 4 h workload was evident, which can be attributed to localized muscular fatigue, but this was not sufficient to impact muscle activity during postural stability tasks.
Highlights
Physical overexertion is one of the primary events or type of exposure that leads to injuries, illnesses, and fatalities in occupational settings
Even though muscle activity during postural stability tasks was not influenced by the low-intensity workload, previous findings from the current study reported decrements in postural stability over the 4 h duration [2], suggesting that postural stability can change with any significant difference in muscle activity
The findings from the current analysis suggest that occupational footwear type does not influence lower extremity muscle activity both during maximal exertions and during postural stability tasks
Summary
Physical overexertion is one of the primary events or type of exposure that leads to injuries, illnesses, and fatalities in occupational settings. Physical exertions are a common occurrence due to the nature of the type and timing of the work performed, especially in settings such as construction, manufacturing, warehousing, mining, and manual material handling. Such physical exertions and physical demands in combination with the hazardous work conditions contribute to an increase in the risk of occupational falls [1], which are one of the leading causes of both non-fatal and fatal injuries at the workplace. From the perspective of intrinsic factors, the negative impact on postural stability in the above-mentioned studies has been attributed to muscular exertions or fatigue, during which there is an impairment of the proprioceptive/somatosensory system’s ability to control posture. Some of them include: a heel-to-toe drop and heel height, where lower heel-to-toe drops and heel heights support the neutral position of ankle and foot aiding postural stability; a midsole and insole, where a thin and firm midsole and a textured insole aids proprioception and somatosensory feedback; footwear mass, where the lower the mass, the less energy is expended; boot shaft height, where the higher the height, the better the proprioception and somatosensory feedback supporting better postural stability [15]; and outer sole texture, thread and material, which impacts the slip-trip induced fall risk [16,17]
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