Trunk and Gluteus-Medius Muscles' Fatigability During Occupational Standing in Clinical Instructors With Low Back Pain

Abstract

Abstract-Background:Occupational standing is associated with low back pain (LBP) development. Yet, trunk and gluteusmedius muscles' fatigability has not been extensively studied during occupational standing. This study examined and correlated the rectus abdominus (RA), erector-spinae (ES), external oblique (EO), and gluteus-medius (GM) muscles' fatigability on both sides while standing in a confined area for 30min Methods: Median frequency EMG data were collected from 15 female clinical instructors with chronic LBP (group A) and 15 asymptomatic controls (group B) (mean age 29.53±2.4 vs 29.07±2.4years, weight 63.6±7 vs 60±7.8kg, and height 162.73±4 vs 162.8±6cm respectively) using a spectrum analysis program. Data were collected in the first and last 5min of the standing task. Results: Using Mixed three-way ANOVA, group A showed significantly (p<0.05) lower frequencies for the right and left ES, and right GM in the last 5min and significantly higher frequencies for the left RA in the first and last 5min than group B. In addition, the left ES and right EO, ES and GM in group B showed significantly higher frequencies and the left ES in group A showed significantly lower frequencies in the last 5min compared with the first. Moreover, the right RA showed significantly higher frequencies than the left in the last 5min in group B. Finally, there were significant (p<0.05) correlations among the median frequencies of the tested four muscles on the same side and between both sides in both groups. Discussion/Conclusions: Clinical instructors with LBP are more liable to have higher trunk and gluteus-medius muscle fatigue than asymptomatic individuals. Thus, endurance training for these muscles should be included in the rehabilitation of such patients.

Gluteus medius muscle function in people with and without low back pain: a systematic review

“…The 24 articles [3–6, 16–18, 23–39] investigating gluteus medius function included 1088 participants with LBP and 998 healthy controls without LBP (Table 1). Studies included one or more of the following gluteus medius measurement outcomes: electromyographic (EMG) activity level [17, 18, 26, 28, 29, 31, 34, 38], EMG fatigability [24, 31, 34], EMG time to onset [6, 26, 29, 30], EMG time of peak activation [6, 17, 18, 24, 26, 28–31, 34, 38], hip abductor strength [3–5, 16, 25, 29], Trendelenburg sign [5, 16] hip abductor torque [23, 33], trigger points [16, 27, 35, 36], cross sectional area [32, 37], or muscle thickness [39]. Studies conducted these measurements non-weight bearing [3, 4, 6, 25, 27, 30, 32–37, 39], dynamically weight bearing [17, 23, 26, 38] or statically weight bearing [24, 28, 31].…”

“…The length of time participants had LBP within each of the studies varied. Some included acute [25], subacute [4, 35], chronic [16, 18, 23, 24, 27–29, 31, 38, 39], or mixed/unclear durations of LBP [3, 5, 6, 17, 26, 30, 32–34, 36, 37].…”

“…However, the LBP group demonstrated statistically significant more gluteus medius activation.Santos et al 2013 [18]EMG810C, EMG System do Brasil®Participants started kneeling and then were asked to flex their R hip and extend their R knee until the R foot contacted the ground (the L knee remained on the ground). The same process was then repeated on the L limb.R peak amplitude, MED (IQR 1–3 )LBP: 1.25 (1.00–2.16)nLBP: 1.60 (1.00–2.10), p = .007L peak amplitude, MED (IQR 1–3 )LBP: 1.19 (1.04–2.31)nLBP: 1.81 (1.02–2.11), p < .001R iEMG, MED (IQR 1–3 )LBP: 0.66 (0.17–1.00)nLBP 1.00 (0.35–1.48), p = .004L iEMG, MED (IQR 1–3 )LBP: 1.00 (0.57–1.00)nLBP 1.00 (0.87–2.00), p = .001Normalisation: % of average activity during the kneeling task.Not measuredNot measuredR, % of duration of task, MED (IQR 1–3 )LBP: 0.68 (0.11–0.94)nLBP: 0.44 (0.07–0.74), p = .001L, % of duration of task, MED (IQR 1–3 )LBP: 0.86 (0.13–1.00)nLBP: 0.21 (0.05–0.83), p < .001Participants with LBP demonstrated statistically significant lower amounts of glutues medius muscle activity, and later times of peak activation compared to those without LBP.Ringheim et al 2015 [31]EMG TeleMyo 2400 (Noraxon)Participants stood barefoot for 15 min.Start RMS (%Max)LBP: 10.4 (6.3–36.5)nLBP 8.3 (4.9–11.6), p = .19Slope RMS (%Max)LBP: − 1.5 (− 9.1–7.7)nLBP: − 0.6 (− 1.7–3.5), p = .66Normalisation: % of maximum voluntary contraction during standing hip flexion and extension in an isokinetic device.Coefficient of variation LBP: 27.4 (23.4–48.5)nLBP: 31 (17.5–39.7), p = .62Slope MDF (Hz/min) LBP: 12.9 (− 9.0–21.3)nLBP: 2.5 (− 8.0–21.3), p = .28Not measuredNot measuredNo statistically significant differences in the amount of gluteus medius muscle activity or variability of muscle activity over time between those with and without LBP.Embaby et al 2013 [24]Myomonitor® Wireless EMG SystemParticipant stood shod for 30 min.Not measuredR first 5 min, MDFLBP: 172.40 (±48.96)nLBP: 171.41 (±38.87), p > .05R Last 5 min, MDFLBP: 158.91 (±49.03) nLBP: 195.19 (±34.74), p < .05L First 5 min, MDFLBP: 159.29 (±48.81) nLBP: 173.12 (±41.36), p > .05L Last 5 min, MDFLBP: 177.18 (±53.95) nLBP: 185.04 (±48.04), p > .05Not measuredNot measuredParticipants with LBP demonstrated statistically significant less gluteus medius muscle activity on the R during the last 5 min compared to those without LBP (indicating greater fatigue). Differences in the first 5 min on both sides, and the last 5 min on the L side, were not statistically significant.Hungerfor-d et al 2003 [26]Noraxon Telemyo 8 EMGParticipants stood on one leg then flexed the contralateral hip and knee to 90 degrees.…”

“…Three studies [24, 31, 34] measured the fatigability of the gluteus medius muscle with EMG (Table 2). Embaby et al [24] found that those with LBP demonstrated statistically significant greater gluteus medius muscle fatigability after 30 min of standing compared to those without LBP, although this finding was only on the right side.…”

“…Three studies [24, 31, 34] measured the fatigability of the gluteus medius muscle with EMG (Table 2). Embaby et al [24] found that those with LBP demonstrated statistically significant greater gluteus medius muscle fatigability after 30 min of standing compared to those without LBP, although this finding was only on the right side. Of the other two studies, one measured gluteus medius fatigability in a static weight bearing position [31], and the other in a non-weight bearing position [34], with both finding no statistically significant differences in the rate of gluteus medius muscle fatigability between those with and without LBP.…”