HDsEMG Activity of the Lumbar Erector Spinae in Violin Players: Comparison of Two Chairs

Abstract

This study compared an ergonomic alternative chair (A-chair) with a standard orchestra chair (O-chair) used by a group of 9 violin players. The features of the high-density surface EMG (HDsEMG) of the lumbar erector spinae muscles were used for the comparison. The violinists played the same pieces of music for 2 hrs without interruption on each chair in 2 different days, 1 week apart. HDsEMG was recorded for 20 s every 5 minutes using two electrode arrays of 16 × 8 electrodes each, one on each side of the spine and placed between the T11 and L4 levels. The sEMG was non-stationary and burst-like patterns were observed on 8 out of 9 violinists. The mean root mean square (RMS) and mean spectral frequency (MNF) value over the region of activity (ROA), the centroid of the ROA, the rates of change in time of the spatial mean of the RMS and MNF values, and the burst frequencies associated with the two chairs were compared. Statistically significant reductions of RMS were observed in each violinist between the O-chair and A-chair (range 11.80−78.36%). No significant changes of other spatial or spectral sEMG features were globally observed versus time or between chairs but were demonstrated by some subjects. It is concluded that the A-chair is associated with a decrease of the sEMG amplitude of the ESM without changes of the spatial and temporal patterns of muscle activation.

High Density Surface Electromyography Activity of the Lumbar Erector Spinae Muscles and Comfort/Discomfort Assessment in Piano Players: Comparison of Two Chairs

“…In seven subjects (44%) out of 16, the signals from most electrode pairs, presented visually evident burst-like activity patterns as observed previously ( Cattarello et al, 2018 ; Russo et al, 2019 ) on the same muscles. These bursts were observed to last 100–390 ms and repeating about 1.5–2.5 times per second.…”

“…These comparisons (Table 2) showed that 14 (87.5%) of the 16 subjects had statistically greater values of the RMS ROA on the SS than on the A-Chair on both left and right sides. As mentioned in section "Discussion, " these results are in agreement with Wilcoxon signed-rank tests carried out on violinists (Russo et al, 2019).…”

“…In a previous preliminary study (Cattarello et al, 2018), biomechanical and short term (5 min) high density surface electromyography (HDsEMG) measurements were used to compare violinists and pianists sitting on a series of different chairs (Varier Move and Varier HAG with and without lumbar support) and on a standard orchestra chair. A further study based on these findings (Russo et al, 2019) concluded that, in violinists, the A-chair (same as the one used in this study) was associated to a lower amplitude of HDsEMG of the ESM, without changes of the spatial and temporal patterns of muscle activity.…”

“…Twelve 20 s measurements were performed during 55 min of play, 5 min apart, on each subject for both chairs. Statistical tests concerning sEMG RMS values were the same as adopted in previous work ( Russo et al, 2019 ) and based on the Wilcoxon signed-rank test. Dunn’s post hoc tests were used to allow for multiple comparisons adjustments.…”

“…Other studies indicate that properly shaped chairs with lumbar support are preferable to the standard piano stools (SS) and may reduce PRMD in pianists ( Grieco et al, 1989 ; Honarmand et al, 2018 ). This has been further explored on other types of musicians ( Foxman and Burgel, 2006 ; Cattarello et al, 2018 ; Russo et al, 2019 ) concluding that chairs with appropriate lumbar support and a trunk-thigh angle of 115° ± 10°, demonstrated to preserve the physiological spine lordosis angle corresponding to a high-perceived comfort ( Keegan, 1953 ; Bendix and Biering-Sørensen, 1983 ), and might reduce the activity of back muscles; however, quantitative and qualitative assessments and comparisons are still lacking. The need for further research associating these elements is evidenced by recent studies and systematic reviews ( Kenny and Ackermann, 2015 ; Berque et al, 2016 ).…”