Abstract
Bending forward and squatting down are two common physical tasks in everyday life and at work. This study determined the sEMG characteristics between erector spinae and vastus lateralis during bending forward and squatting down tasks by analyzing the regularity of variation in sEMG frequency domain index-median frequency (MNF) in healthy subjects. The results indicate that sEMG activities in erector spinae are significantly higher than those in the right vastus lateralis during bending forward task. Instead, in squatting down task, sEMG activities in the right vastus lateralis are significantly greater than those in erector spinae. It also shows that the fatigue degree of low back caused by trunk bending is much deeper than that by squatting down. The ratio scope of one-order fitting values of MNF between erector spinae and vastus lateralis ranges from 0.87 to 1.72 among 80% of subjects during bending forward task and ranges from 0.31 to 1.11 during squatting down task. This study provides certain theoretical basis for using the strength of low back in a proper way to avoid getting it hurt in daily physical activities.
Highlights
Bending forward is a common physical task in everyday life and at work
What is more, using the strength of low back incorrectly and prolonged trunk bending have been treated as risk factors for low back pain (LBP)
The results showed that activities of gluteus maximus muscle during the flexion-extension cycle were reduced in patients with chronic low back pain [18]
Summary
Bending forward is a common physical task in everyday life and at work. For example, people must bend down when they carry heavy loads or pick up something on the ground. When people do the housework, they often keep their bodies in forward flexion condition. In these cases, if people do not pay attention to their posture, especially for those who lack exercise, it is easy to cause damage to low back. What is more, using the strength of low back incorrectly and prolonged trunk bending have been treated as risk factors for low back pain (LBP). Due to increased pain and/or muscle weakness, individuals with LBP often have difficulty in performing trunk bending and lifting task. In order to avoid aggravating the burden of low back, people with or without LBP will consciously rely on the power of lower limbs muscle to implement some actions, such as squatting down
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