A Study on Effects of Muscle of Lower Limb Associated with Whole-Body Vibration
Long-term exposure to whole-body vibration in the workplace will increase the chances of lower back pain, spinal disc herniation, and other diseases. However, many studies have also indicated that vibration stimulation, often used in physical therapy, clinical treatment, and muscle strength training, has a variety of positive effects for the human body.
A commercially available electric vibrating machine was chosen, and 20 subjects were recruited to statically stand on the vibration platform with knee flex at different angles (0o, 60o, 90o), and to dynamically stand (squatting and rising) on the platform, while being exposed to different vibration frequencies (0 Hz, 20 Hz, 35 Hz, 50 Hz). The experiment used surface electromyography to assess the effects of posture and frequency on the neuromuscular activation. Each subject was asked to rate the perceived exertion on three monitored muscles (gastrocnemius, rectus femoris, vastus lateralis).
The results showed that the knee flex angle had a significant effect on the muscles of the lower limbs, especially the thigh muscles, which were regarded as the support for body weight, and that the most obvious impact on the lower limb muscles was on the calf muscles during whole-body vibration. Surface EMG signals detected in dynamic posture were generally higher than those in static posture; however, through the subjective perception and assessment of subjects, we found that the scores of the two situations were quite close. The study results showed that the higher-frequency vibration activated muscles more easily. However, excessive fatigue would also result in injuries, a cause for caution and care.
KeywordsWhole-body vibration EMG Muscle fatigue Lower limb
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