Isometric Trunk Extension Research Articles

Effect of corporal suspension and pendulum exercises on neuromuscular properties and functionality in patients with medullar thoracic injury

BackgroundTraumatic spinal cord injury (TSCI) is one of the most devastating injuries that has a physical impact on patients. The CHORDATA® method involves suspension and pendulous exercises and has been clinically used to treat patients with TSCI. Although empirically used to treat neurological patients, there is no scientific evidence of the efficacy of this method. PurposeTo evaluate the chronic effects of CHORDATA® method on torque, muscle activation, muscle thickness, and functionality in patients with traumatic spinal cord injury. MethodsTwenty-six male patients with medullar thoracic injury were randomly categorised into two groups: intervention group (n = 14) and control group (n = 12). Rehabilitation program comprised of 16 sessions of body suspension and pendulum exercises (twice/week). The maximal voluntary isometric trunk flexion and extension torques, muscle activation and thickness (external and internal oblique, rectus and transversus abdominis, longissimus, and multifidus muscles), and functionality (adapted reach test) were evaluated before and after of rehabilitation program. FindingsA significant increase was observed in maximal voluntary isometric torque (flexion, 58%; extension, 76%), muscle activation of the rectus abdominis muscle, and muscle thickness of all intervention group muscles, without changes in the control group. Compared to the pre-intervention period, the intervention group also showed improvement in functionality at post-intervention, but no such differences were noted in the control group. InterpretationThe corporal suspension and pendulum exercises training improved rectus abdominis muscle activation, trunk muscles structure and strength, and reaching capacity in medullar thoracic injury patients.

Trunk Muscle Strength After Lumbar Spine Fusion: A 12-Month Follow-up.

ObjectiveThe aim of this study was to investigate changes in trunk muscle strength 12 months after lumbar spine fusion (LSF) compared to preoperative strength. MethodsA total of 194 patients (mean±standard deviation [SD] age, 61±21 years) who underwent LSF participated in this prospective longitudinal study. Physical measurements of the participants were made before surgery and 12 months postoperatively. Isometric trunk extension and flexion strength was measured using a strain-gauge dynamometer in the standing position. Strength changes were calculated. Regression analysis was performed to explore which factors predicted strength levels at 12 months postoperatively. ResultsThe preoperative mean±SD extension strength was 205±144 N, which increased to 258±142 N (p<0.001) at the 12-month follow-up. Flexion strength increased from 295±172 N to 364±164 N (p<0.001). The preoperative extension/flexion strength ratio was 0.75±0.38 and remained similar (0.73±0.26) at 12 months postoperatively (p=0.39). ConclusionAlthough trunk muscle strength increased by 26% for extension and 23% for flexion at the 12-month postoperative follow-up, both values remained objectively low. In addition, flexion strength remained higher than extension strength, which indicates an imbalance between those muscle groups. Age, severe back pain, and low trunk muscle strength before surgery predicted low trunk muscle strength at 1 year after spinal fusion.

Reliability and validity of trunk flexor and trunk extensor strength measurements using handheld dynamometry in a healthy athletic population

ObjectivesTo investigate reliability and validity of handheld dynamometry (HHD) strength tests to accurately measure isometric trunk flexion and extension strength. DesignTest-retest design and comparative analysis to investigate reliability and validity respectively. SettingIsometric trunk flexion and extension strength, measured with a handheld dynamometer, was compared to isometric strength testing on a stationary isokinetic dynamometer. Different test positions were examined for the HHD measurements for trunk flexion and extension strength. Main outcome measuresTrunk muscle strength was calculated in newton metres (Nm) for both devices. Results of both devices were compared with Pearson correlations and agreement between both methods was explored with Bland-Altman plots. ICC values were calculated to assess HHD intra- and inter-tester reliability. ResultsReliability was good to excellent for all HHD tests (ICC = 0.67–0.93). High correlations were found between the HHD tests and stationary dynamometer tests (r = 0.65–0.86). Bland-Altman plots showed agreement between both methods for the trunk flexion test, supported in 30° trunk flexion and for the trunk extension test in a prone position in 0° trunk flexion. ConclusionHandheld dynamometry is reliable and a clinically applicable valid method to evaluate isometric trunk flexion and extension strength.

Exercise-induced trunk fatigue decreases double poling performance in well-trained cross-country skiers.

To examine the effects of exercise-induced trunk fatigue on double poling performance, physiological responses and trunk strength in cross-country skiers. Sixteen well-trained male cross-country skiers completed two identical pre- and post-performance tests, separated by either a 25-min trunk fatiguing exercise sequence or rest period in a randomized, controlled cross-over design. Performance tests consisted of a maximal trunk flexion and extension test, followed by a 3-min double poling (DP) test on a ski ergometer. Peak torque during isometric trunk flexion (- 66%, p < .001) and extension (- 7.4%, p = .03) decreased in the fatigue relative to the control condition. Mean external power output during DP decreased by 14% (p < .001) and could be attributed both to reduced work per cycle (- 9%, p = .019) and a reduced cycle rate (- 6%, p = .06). Coinciding physiological changes in peak oxygen uptake (- 6%, p < .001) and peak ventilation (- 7%, p < .001) could be observed. Skiers chose a more even-pacing strategy when fatigued, with the performance difference between fatigue and control condition being most prominent during the first 2min of the post-test. In well-trained cross-country skiers, exercise-induced trunk fatigue led to a substantial decrease in DP performance, caused by both decreased work per cycle and cycle rate and accompanied by reduced aerobic power. Hence, improved fatigue resistance of the trunk may therefore be of importance for high-intensity DP in cross-country skiing.

Muscle Strength and Neuromuscular Control in Low-Back Pain: Elite Athletes Versus General Population.

The purpose of the study was to investigate the athletic-based specificity of muscle strength and neuromuscular control of spine stability in chronic non-specific low-back pain (LBP). Thirty elite athletes and 29 age-matched non-athletes with (15 athletes and 15 non-athletes) and without LBP (15 athletes and 14 non-athletes) participated in the study. Muscle strength was measured during maximal isometric trunk flexion and trunk extension contractions. The neuromuscular control of spine stability was analyzed by determining trunk stiffness, trunk damping, and onset times of the lumbar and thoracic erector spinae muscles after sudden perturbations (quick release experiments) as well as maximum Lyapunov exponents (local dynamic stability) using non-linear time series analysis of repetitive lifting movements. LBP was assessed using the visual analog scale. We found lower maximal trunk extension moments (p = 0.03), higher trunk damping (p = 0.018) and shorter onset times (p = 0.03) of the investigated trunk muscles in LBP patients in both athletes and non-athletes. Trunk stiffness and the local dynamic stability did not show any differences (p = 0.136 and p = 0.375, respectively) between LBP patients and healthy controls in both groups. It can be concluded that, despite the high-level of training in athletes, both athletes and non-athletes with LBP showed the same deconditioning of the lumbar extensor muscles and developed similar strategies to ensure spine stability after sudden perturbations to protect the spine from pain and damage. The findings highlight that specific training interventions for the trunk muscles are not only crucial for individuals of the general population, but also for well-trained athletes.

Intervertebral disc status is associated with vertebral marrow adipose tissue and muscular endurance.

Low back pain is a major public health issue. Identifying factors associated with better intervertebral disc (IVD) characteristics gives insight into IVD metabolism and highlights intervention targets for improvement of IVD health. This cross-sectional study investigates whether IVD T2-relaxation time on magnetic resonance imaging (MRI) is associated with vertebral fat fraction (VFF; to quantify marrow adipose tissue), trunk muscle cross-sectional area (CSA), muscle function and physical activity (PA). Seventy-nine healthy subjects (35 males, 44 females) without history of spinal disease were included. Lumbar IVDs T2-relaxation time, lumbar VFF and CSA of multifidus, erector spinae, quadratus lumborum, and psoas muscles were quantified via MRI. Isometric trunk flexion and extension endurance times as well as habitual PA levels and exposure to occupational spine risk factors were documented. Pearson-partial correlations adjusted for anthropometric differences by controlling for vertebral body height. Higher IVD T2-time correlated with: (a) lower VFF (r = -0.27, p < 0.05), (b) greater trunk extensor muscle endurance (r = 0.37, p < 0.01), and (c) greater trunk flexor muscle endurance (r = 0.30, p < 0.01) but not with muscle CSA. Lower VFF also correlated with greater extensor muscle endurance (r = -0.26, p < 0.05) and habitual PA (MET-mins per week) (r = -0.24, p < 0.05). This is the first study to show that better IVD hydration is associated with lower VFF and that greater physical activity is associated with favourable levels of vertebral marrow adipose tissue in young healthy individuals. Reduced vertebral marrow adipose tissue may specifically improve IVD hydration via improved nutrient supply. These slides can be retrieved under Electronic Supplementary Material.

Estimating Neural Control from Concentric vs. Eccentric Surface Electromyographic Representations during Fatiguing, Cyclic Submaximal Back Extension Exercises.

Purpose: To investigate the differences in neural control of back muscles activated during the eccentric vs. the concentric portions of a cyclic, submaximal, fatiguing trunk extension exercise via the analysis of amplitude and time-frequency parameters derived from surface electromyographic (SEMG) data.Methods: Using back dynamometers, 87 healthy volunteers performed three maximum voluntary isometric trunk extensions (MVC's), an isometric trunk extension at 80% MVC, and 25 cyclic, dynamic trunk extensions at 50% MVC. Dynamic testing was performed with the trunk angular displacement ranging from 0° to 40° and the trunk angular velocity set at 20°/s. SEMG data was recorded bilaterally from the iliocostalis lumborum at L1, the longissimus dorsi at L2, and the multifidus muscles at L5. The initial value and slope of the root mean square (RMS-SEMG) and the instantaneous median frequency (IMDF-SEMG) estimates derived from the SEMG recorded during each exercise cycle were used to investigate the differences in MU control marking the eccentric vs. the concentric portions of the exercise.Results: During the concentric portions of the exercise, the initial RMS-SEMG values were almost twice those observed during the eccentric portions of the exercise. The RMS-SEMG values generally increased during the concentric portions of the exercise while they mostly remained unchanged during the eccentric portions of the exercise with significant differences between contraction types. Neither the initial IMDF-SEMG values nor the time-course of the IMDF-SEMG values significantly differed between the eccentric and the concentric portions of the exercise.Conclusions: The comparison of the investigated SEMG parameters revealed distinct neural control strategies during the eccentric vs. the concentric portions of the cyclic exercise. We explain these differences by relying upon the principles of orderly recruitment and common drive governing motor unit behavior.

Effect of abdominal bracing training on strength and power of trunk and lower limb muscles.

It is unknown whether maximal voluntary co-contraction of abdominal muscles, called abdominal bracing, can be a training maneuver for improving strength and power of trunk and lower limb muscles. The present study aimed to elucidate this. Twenty young adult men (23.3±1.8years) were allocated to training (TG, n=11) or control (CG, n=9) group. TG conducted an 8-week training program (3days/week) consisting of 2-s maximal abdominal bracing followed by 2-s muscle relaxation (5×10repetitions/day). Maximal voluntary isometric strength during trunk flexion and extension, hip extension, and knee extension, maximal lifting power from sitting position, and the thicknesses of abdominal muscles were measured before and after the intervention. In addition, surface electromyograms from trunk and lower limb muscles and intra-abdominal pressure (IAP) during the maximal abdominal bracing and maximal lifting tasks were also determined. After the intervention, TG showed significant increases in isometric trunk extension (+14.4%) and hip extension (+34.7%) strength and maximal lifting power (+15.6%), while CG did not show any changes in strength and power variables. Furthermore, TG had significant gains in the muscle thickness of the oblique internal (+22.4%), maximal IAP during abdominal bracing (+36.8%), and the rate of IAP rise during lifting task (+58.8%), without corresponding changes in CG. The current study indicates that a training style with maximal voluntary co-contraction of abdominal muscles can be an effective maneuver for increasing strength and power during movements involving trunk and hip extensions, without using external load.

Effects of a 16-week Pilates exercises training program for isometric trunk extension and flexion strength

To evaluate the effects of Pilates exercises designed to improve isometric trunk extension and flexion strength of muscles in women with chronic low back pain (cLBP). Female volunteers with cLBP were divided into an experimental group (EG; n=27) and a control group (CG; n=27). Pilates exercises were performed twice per week by the EG; the duration of each session was 60min. The program lasted for 16 weeks; thus patients underwent a total of 32 exercise sessions. The maximum isometric waist bending strength of the EG had improved significantly (p=0.001) after 16 weeks of the Pilates program. The results of trunk flexion muscle endurance tests significantly depended on the trunk extension muscle endurance before the intervention, and at 1 month (r=0.723, p<0.001) and 2 months (r=0.779, p<0.001) after the Pilates exercise program. At the end of the 16-week exercise program, cLBP intensity decreased by 2.01±0.8 (p<0.05) in the EG, and this reduction persisted for 1 month after completion of the program. At 1 and 2 months after cessation of the Pilates exercise program the pain intensified and the functional state deteriorated much faster than the maximum trunk muscle strength. Therefore, it can be concluded that, to decrease pain and improve functional condition, regular exercise (and not only improved strength and endurance) is required. We established that, although the 16-week lumbar stabilization exercise program increased isometric trunk extension and flexion strength and this increase in strength persisted for 2 months, decreased LBP and improved functional condition endured for only 1 month.

Pilates vs. Balance Training in Healthy Community-Dwelling Seniors: a 3-arm, Randomized Controlled Trial.

The study examined effects of traditional balance vs. mat-based Pilates training on balance and trunk strength in healthy community dwellers. Forty-eight seniors were either stratified to a balance training group (BAL, n=16, 69.1 (SD 5.8) y), Pilates training group (PIL, n=17, 70.8 (6.5) y) or control group (CON, n=15, 69.2 (6.1) y). BAL performed traditional balance training, while PIL conducted mat-based Pilates-exercises (8 weeks, 2 sessions/week 66 min each). Balance performance (single limb stance and perturbed kneeling, Y-Balance test), dynamic and isometric trunk flexion and extension were assessed during pre- and post-testing. According to the magnitude-based inference approach, substantial positive effects in favor of BAL compared to CON were found for the Y-balance score (right leg, effect size (d)=0.68; left leg, d=0.56), trunk extension (d=0.68) and single leg stance (right leg, d=0.61; left leg, d=0.38). Dynamic (d=0.32) and isometric (d=0.15) trunk flexion revealed unclear effects. For the Y-balance score (right leg, d=0.48, left leg, d=0.75) and single leg stance (right leg, +d=0.61%; left leg, d=0.67), interestingly, BAL substantially exceeded PIL. PIL vs. CON revealed unclear effects for most parameters (0.05

Pilates vs. Balance Training in Health Community-Dwelling Seniors: a 3-arm, Randomized Controlled Trial.

The study examined effects of traditional balance vs. mat-based Pilates training on balance and trunk strength in healthy community dwellers. Forty-eight seniors were either stratified to a balance training group (BAL, n=16, 69.1 (SD 5.8) y), Pilates training group (PIL, n=17, 70.8 (6.5) y) or control group (CON, n=15, 69.2 (6.1) y). BAL performed traditional balance training, while PIL conducted mat-based Pilates-exercises (8 weeks, 2 sessions/week 66 min each). Balance performance (single limb stance and perturbed kneeling, Y-Balance test), dynamic and isometric trunk flexion and extension were assessed during pre- and post-testing. According to the magnitude-based inference approach, substantial positive effects in favor of BAL compared to CON were found for the Y-balance score (right leg, effect size (d)=0.68; left leg, d=0.56), trunk extension (d=0.68) and single leg stance (right leg, d=0.61; left leg, d=0.38). Dynamic (d=0.32) and isometric (d=0.15) trunk flexion revealed unclear effects. For the Y-balance score (right leg, d=0.48, left leg, d=0.75) and single leg stance (right leg, +d=0.61%; left leg, d=0.67), interestingly, BAL substantially exceeded PIL. PIL vs. CON revealed unclear effects for most parameters (0.05<d<0.36). Mat-based Pilates training did not cause relevant adaptations in trunk strength and balance performance, whereas balance training substantially improved balance and trunk strength.

The Effects of Vibration and Muscle Fatigue on Trunk Sensorimotor Control in Low Back Pain Patients.

IntroductionChanges in sensorimotor function and increased trunk muscle fatigability have been identified in patients with chronic low back pain (cLBP). This study assessed the control of trunk force production in conditions with and without local erector spinae muscle vibration and evaluated the influence of muscle fatigue on trunk sensorimotor control.MethodsTwenty non-specific cLBP patients and 20 healthy participants were asked to perform submaximal isometric trunk extension torque with and without local vibration stimulation, before and after a trunk extensor muscle fatigue protocol. Constant error (CE), variable error (VE) as well as absolute error (AE) in peak torque were computed and compared across conditions. Trunk extensor muscle activation during isometric contractions and during the fatigue protocol was measured using surface electromyography (sEMG).ResultsForce reproduction accuracy of the trunk was significantly lower in the patient group (CE = 9.81 ± 2.23 Nm; AE = 18.16 ± 3.97 Nm) than in healthy participants (CE = 4.44 ± 1.68 Nm; AE = 12.23 ± 2.44 Nm). Local erector spinae vibration induced a significant reduction in CE (4.33 ± 2.14 Nm) and AE (13.71 ± 3.45 Nm) mean scores in the patient group. Healthy participants conversely showed a significant increase in CE (8.17 ± 2.10 Nm) and AE (16.29 ± 2.82 Nm) mean scores under vibration conditions. The fatigue protocol induced erector spinae muscle fatigue as illustrated by a significant decrease in sEMG median time-frequency slopes. Following the fatigue protocol, patients with cLBP showed significant decrease in sEMG root mean square activity at L4-5 level and responded in similar manner with and without vibration stimulation in regard to CE mean scores.ConclusionsPatients with cLBP have a less accurate force reproduction sense than healthy participants. Local muscle vibration led to significant trunk neuromuscular control improvements in the cLBP patients before and after a muscle fatigue protocol. Muscle vibration stimulation during motor control exercises is likely to influence motor adaptation and could be considered in the treatment of cLBP. Further work is needed to clearly identify at what levels of the sensorimotor system these gains are achievable.

Effects of Munari Powder on Physical and Sensory-motor Parameters: A Preliminary Report.

Munari powder is broadly used in physical medicine and rehabilitation to decrease pain and help normalize sensory-motor function. It operates as TPRV1 agonist and “stops” generation of action potentials in pain nerve fibers. This is a short report of a pilot study on 20 subjects. Every subject underwent four visits to our laboratory, where the Munari applications and related measurements of its effects took place. Each of the healthy adults received the following applications: (1) placebo, i.e. 0% cayenne pepper mixture, consisting only of water and kaolin, (2) weak, i.e. 2.5% cayenne pepper mixture, (3) medium, i.e. 5.0% cayenne pepper mixture, and (4) strong, i.e. 10% cayenne pepper mixture. The assessments were carried out before the Munari powder patch application, right after the application, and 15 and 30 min after the termination of the 20-minute Munari powder patch application. We measured subjective cold/hot feeling on visual analogue scale, blood pressure, body temperature, skin light touch sensations, sense for two-point discrimination, and pain threshold to the mechanical stimulus. Besides these tests, maximal voluntary force during isometric trunk extension and the sitting balance test were performed. The preliminary results indicate that the 5% concentration of cayenne pepper mixture is the best choice because no additional effects were observed with the 10% concentration and the effects are higher than with 2.5% concentration. Whether this will be also thrue for the patients suffering pain ought to be determined.

Reorganised motor control strategies of trunk muscles due to acute low back pain

This study assessed how the low back motor control strategies were affected by experimental pain. In twelve volunteers the right m. longissimus was injected by hypertonic and isotonic (control) saline. The pain intensity was assessed on a visual analog scale (VAS). Subjects were seated on a custom-designed chair including a 3-dimensional force sensor adjusted to the segmental height of T1. Electromyography (EMG) was recorded bilaterally from longissimus, multifidus, rectus abdominis, and external oblique muscles. Isometric trunk extensions were performed before, during, and after the saline injections at 5%, 10%, and 20% of maximum voluntary contraction force. Visual feedback of the extension force was provided whereas the tangential force components were recorded. Compared with isotonic saline, VAS scores were higher following hypertonic saline injections (P<.01). Experimental low back pain reduced the EMG activity bilaterally of the rectus abdominis muscles during contractions at 10% and 20% MVC (P<.01) although force accuracy and tangential force variability was not affected. Increased variability in the tangential force composition was found during pain compared with the non-painful condition (P<.05). The immediate adaptation to pain was sufficient to maintain the quality of the task performance; however the long-term consequence of such adaptation is unknown and may overload other structures.

Sensorimotor Control During Peripheral Muscle Vibration: An Experimental Study

ObjectiveThe aims of this study were to determine whether the application of vibration on a postural lower limb muscle altered the sensorimotor control of its joint as measured by isometric force production parameters and to compare present findings with previous work conducted on trunk muscle. MethodsTwenty healthy adults were asked to reproduce submaximal isometric plantar flexion under 3 different conditions: no vibration and vibration frequencies of 30 and 80 Hz on the soleus muscle. Time to peak torque, variable error, as well as constant error and absolute error in peak torque were calculated and compared across conditions. ResultsUnder vibration, participants were significantly less accurate in the force reproduction task, as they mainly undershot the target torque. Applying an 80-Hz vibration resulted in a significantly higher negative constant error than lower-frequency vibration (30 Hz) or no-vibration condition. Decreases in isometric force production accuracy under vibration influence were also observed in a previous study conducted on trunk muscle. However, no difference in constant error was found between 30- and 80-Hz vibration conditions. ConclusionThe results suggest that acute soleus muscle vibration interferes with plantar flexion torque generation by distorting proprioceptive information, leading to decreases in accuracy of a force reproduction task. Similar results in an isometric trunk extension force reproduction task were found with vibration applied on erector spinae muscle. However, high-frequency vibration applied on soleus muscle elicited higher force reproduction errors than low-frequency stimulation.

Force capacity of back extensor muscles in healthy males: effects of age and recovery time.

To judge a person's maximum trunk extension performance as either age-appropriate or deconditioned is challenging. The current study aimed at determining age and anthropometrically adjusted maximum voluntary contraction (MVC) of back extensors considering the number and recovery time between trials. Thirty-one younger (20-30 years) and 33 older (50-60 years) healthy males performed five repetitions of maximal isometric trunk extensions in an upright standing position with randomized recovery times ranging between one to five minutes at one minute intervals. Torque values were normalized according to the individual's upper body mass resulting in upper body torque ratios (UBTR). To evaluate the impact of age, recovery time, and fatigue on UBTR we applied a linear mixed-effects model. Based on surface EMG data muscular fatigue could be excluded for both groups. For all MVC trials, UBTR levels differed significantly between age groups (range of mean values: younger: 2.26-2.28, older: 1.78-1.87, effect size: 1.00) but were independent from recovery time. However, the older males tended to exert higher UBTR values after shorter recovery periods. The study provides normative values of anthropometrically and age-group adjusted maximum back extensor forces. For the investigated groups, only two MVC trials with a recovery time of about one minute seem appropriate.

A Home-Based Program of Transcutaneous Electrical Nerve Stimulation and Task-Related Trunk Training Improves Trunk Control in Patients With Stroke

Background. Impaired trunk motor control is common after stroke. Combining transcutaneous electrical nerve stimulation (TENS) with task-related trunk training (TRTT) has been shown to enhance the recovery of lower limb motor function. Objective. This study investigated whether combining TENS with TRTT would enhance trunk control after stroke. Methods. Thirty-seven subjects with stroke were recruited into a randomized controlled clinical trial. Subjects were randomly assigned to any one of the three 6-week home-based training groups: (1) TENS + TRTT, (2) placebo TENS + TRTT, or (3) control without active training. The outcome measures included isometric peak trunk flexion torque and extension torque; forward seated and lateral seated reaching distance to the affected and unaffected side; and Trunk Impairment Scale (TIS) scores. All outcome measures were assessed at baseline, after 3 and 6 weeks of training, and 4 weeks after training ended at follow-up. Results. Both the TENS + TRTT and the placebo-TENS + TRTT groups had significantly greater improvements in isometric peak trunk flexion torque and extension torque, lateral seated reaching distance to affected and unaffected side, and TIS score than the control group after 3 weeks of training. The TENS + TRTT group had significantly greater and earlier improvement in its mean TIS score than the other 2 groups. Conclusions. Home-based TRTT is effective for improving trunk muscle strength, sitting functional reach and trunk motor control after stroke in subjects without somatosensory deficits. The addition of TENS to the trunk augments the effectiveness of the exercise in terms of TIS scores within the first 3 weeks of training.

TRUNK MOTION AND MUSCULAR STRENGTH AFFECT KNEE VALGUS MOMENT DURING SINGLE-LEG LANDING AFTER OVERHEAD STROKE IN BADMINTON

BackgroundAnterior cruciate ligament (ACL) injury in knees opposite to the racket-hand side frequent occurs during single-leg landing after overhead stroke in badminton. Although large lateral inclination of trunk during single-leg...

Properties of Force Output and Spectral EMG in Young Patients with Nonspecific Low Back Pain during Isometric Trunk Extension

[Purpose] To clarify the influence of nonspecific low back pain (NSLBP) on force fluctuation and the myoelectric data of back muscles during isometric trunk extension at low to high force levels. [Subjects] Fourteen male subjects with NSLBP and 14 healthy male control subjects participated in this study. [Methods] All participants extended their trunk isometrically maintaining 10 levels of target force [2, 5, 10, 15, 20, 30, 50, 70, 80 and 90% of maximal voluntary contraction (MVC) in a random order] for about 4 seconds with visual feedback. A force transducer and tri-axis force sensor were positioned at the 7th thoracic vertebra to measure force output and the direction of force. Myoelectric activities of the back muscles (longissimus thoracis, L2 level; multifidus, S1 level) were recorded by surface electromyography. [Results] Force output of NSLBP subjects fluctuated more than that of healthy subjects at 30% and 50%MVC. Higher median power frequency in the multifidus was observed in NSLBP subjects at moderate to high force levels. [Conclusion] These results show that the properties of force output in NSLBP subjects differ from those in healthy subjects, suggesting that the assessment of force fluctuation of back muscles at moderate force levels is a useful index for evaluating and discriminating NSLBP.

Reliability of isometric trunk moment measurements in healthy persons over 50 years of age

To determine the short- and long-term test-retest reliability of maximum isometric trunk moment measurements in healthy volunteers over 50 years of age, to compare these results with those from volunteers younger than 50 years, and to test whether volunteers' anticipatory emotional state affects the precision of these measurements. Forty-two older persons (21 females; age range 50-90 years) and 44 younger persons (19 females; age range 18-49 years) performed maximum isometric trunk extensions, flexions, and rotations using dynamometers (DAVID, Fi, David Health Solutions Ltd, Helsinki, Finland). They repeated the tests after 1-2 days (short-term) and at 6 weeks (long-term). Retest-reliability was evaluated for age- and gender-specific subgroups, with assessment of intraclass correlation coefficient (ICC2,1) , standard error of measurement, smallest real difference, and smallest real difference, in percent. For the elderly group, smallest real difference, in percent values varied up to 33% and were similar to those obtained from young volunteers. Precision of the trunk rotation tests was lower than that of trunk flexion or extension. Retest agreement exceeded 0.75 (ICC2,1) for all tests, with no relevant differences observed between gender- and age-specific subgroups. Neither participants' motivation nor their anticipatory emotions correlated with the individual coefficients of variation of the trunk muscle moment measurements. Isometric maximum trunk extension and flexion moment measurements taken from healthy persons > 50 years old are as reliable as those from persons < 50 years old, and can be expected to enable an acceptable level of detection of expected changes in muscle strength parameters as a result of planned exercise interventions.