Effects of handicraft sitting postures on lower trunk muscle fatigue

Abstract

The purpose of this study was to assess trunk muscle fatigue in seated handicraft tasks using surface electromyography (sEMG) and visual analogue scale (VAS) ratings for trunk discomfort, and to assess the relationship of these responses. Twenty-three participants were randomly assigned to assumed crossed-leg and heel sitting postures for 30 min. Normalised median frequency (NMF) slopes for lumbar multifidus (LM) and internal oblique (IO) muscles and VAS ratings were recorded. Results revealed that the crossed-leg posture produced significantly steeper NMF slopes for both sides of the LM and IO muscles than heel sitting. Greater VAS ratings were found in crossed-leg sitting posture than the heel sitting posture. The NMF slopes and the VAS ratings had significant negative correlations for both postures. Findings support heel sitting in handicraft tasks over crossed-leg sitting due to greater trunk muscle fatigue and discomfort during the latter posture. Results support VAS ratings as a complementary method to sEMG for identifying trunk muscle fatigue. Practitioner Summary: Trunk muscle fatigue in handicraft work is a potential risk for low back pain. Based on EMG and discomfort analyses, heel sitting is preferred to crossed-leg posture. Discomfort ratings are consistent with EMG measures in identifying trunk muscle fatigue in such postures.

Effects of Shoulder Taping on Discomfort and Electromyographic Responses of the Neck While Texting on a Touchscreen Smartphone

“…Results revealed that NMF slope for the UT, CES, and SCM muscles were not different between shoulder taping and no taping conditions. Generally, muscle fatigue results from a task that requires sustained muscle contraction in static posture or repeated movements, and a steeper NMF slope of the muscle indicates more muscle fatigue [16] , [25] . Previous studies proposed a relationship between alterations of muscle activity and muscle fatigue [36] , [37] .…”

“…Neck discomfort was reported by the participants via texting on the touchscreen smartphone. Neck discomfort was measured using an 11-point (0–10) numerical rating scale (NRS), where 0 represents no discomfort and 10 represents the worst discomfort [25] .…”

“…The secondary outcome measures included normalized root mean square (NRMS) for muscle activity measurement and normalized median frequency slope (NMF slope ) for muscle fatigue measurement measured by a surface electromyography. The EMG setting of a Biopac MP 35 surface EMG system (Biopac, Goleta, CA, USA) was followed a protocol stated previously [25] . The skin over the areas of the UT muscle to be taped, CES, and sternocleidomastoid (SCM) muscles was cleaned with alcohol, and hair was removed when necessary in order to reduce skin impedance to <5 kΩ.…”

Physical and Mental Workload in Single-Incision Laparoscopic Surgery and Conventional Laparoscopy

“…13 Small differences in MF slope in this study revealed that cross-legged floor sitting posture in handicraft work can be fatiguing to lower trunk muscles and cause low back discomfort over time. 13 Although there have been reports comparing laparoscopy to open surgery, or comparing performance between SILS and laparoscopy, our study is one of the first to compare muscle fatigue and mental workload in SILS and standard laparoscopy. Additionally, several previous ergonomic papers using sEMG and frequency analysis might have had methodological problems.…”

Core Stabilization Exercise Improves Pain Intensity, Functional Disability and Trunk Muscle Activity of Patients with Clinical Lumbar Instability:a Pilot Randomized Controlled Study

“…After that, pairs of active disc disposable Ag/AgCl surface electrodes (EL 503) with electrical contact surface areas of 1 cm 2 and a center-to-center spacing of 2.5 cm were attached parallel to each muscle on the right side as previously reported: TrA & IO muscle 19) , RA muscle 20) , LM muscle 21) and ICLT muscle 22) . The two ground electrodes of the right RA and ICLT muscles were placed over the ribcage and the other two ground electrodes of the right TrA & IO and LM muscles were placed over the right iliac crest.…”