Stewart Bruce-Low

The effect of lumbar extension training with and without pelvic stabilization on lumbar strength and low back pain.

INTRODUCTION A dynamometer employing a stabilization procedure (lumbar extension machine, MedX, Ocala, FL) is effective in improving strength and reducing symptoms of low back pain (LBP), and researchers have hypothesized that this effectiveness is due to the pelvic stabilization. However, effects of the dynamometer with and without pelvic stabilization on LBP have not been compared: This was the aim of the present study. METHODS Forty-two chronic LBP patients were randomly assigned to a lumbar extension training with pelvic stabilization group (STAB; n=15), a lumbar extension without pelvic stabilization group (NO-STAB; n=15) and a control group (n=12). STAB and NO-STAB participants completed one weekly session of dynamic variable resistance exercise (one set of 8-12 repetitions to fatigue) on the lumbar extension machine (with or without pelvic stabilization) for 12 weeks. Pre- and post-test measures of self-reported LBP (101-point visual analog scale; pre-test mean of 25), related disability (Oswestry disability index; pre-test mean of 34) and lumbar strength were taken. RESULTS After the exercise program, the STAB group increased significantly in lumbar strength at all joint angles, and decreased significantly in visual analogue and Oswestry scores. However, there were no significant changes in these variables in the NO-STAB and control groups. DISCUSSION Isolated lumbar extension exercise is very effective in reducing LBP in chronic patients. However, when the pelvis is not stabilized, otherwise identical exercises appear ineffective in reducing LBP.

A review of the specificity of exercises designed for conditioning the lumbar extensors

Objective To review the specificity of exercises designed to condition the lumbar extensor musculature (ie, lumbar erector spinae and multifidus). Methods A review of studies examining effects of exercises designed to condition the lumbar extensors was conducted. Included were studies that examined the acute activation and chronic adaptation of the lumbar extensor musculature in response to benches and roman chair trunk extensions, free weights exercises (ie, deadlifts, squats, good-mornings, etc), floor and stability ball exercise (ie, trunk extensions, bridging, four-point kneeling, etc) and resistance machines (ie, those with and without pelvic restraints). Results Evidence suggests that the reviewed exercises designed to condition the lumbar extensors all may result in significant activation of this musculature during their performance. However, examination of training studies shows that for benches and roman chair trunk extensions, free weights exercises, floor and stability ball exercise and resistance machines without appropriate pelvic restraints, evidence suggests that they may be less effective for inducing chronic adaptations in the lumbar extensors as a result of their performance. Contrastingly, resistance machines that employ appropriate pelvic restraint to isolate lumbar extension are better evidenced to confer specific adaptations to the lumbar extensors. Conclusions Numerous exercise approaches have been designed with the intention of conditioning the lumbar extensors. Those examined appear to activate the lumbar extensors; however, the specificity of many of these exercises for producing chronic adaptations may be questionable, potentially due to the compound nature of them allowing involvement of other musculature such as the hip extensors. Many of the reviewed exercises offer potential to condition the lumbar extensors, however, isolation of lumbar extension through appropriate pelvic restraint appears important for optimising specific adaptations in the lumbar extensors.

A reappraisal of the deconditioning hypothesis in low back pain: review of evidence from a triumvirate of research methods on specific lumbar extensor deconditioning

Abstract Objective: ‘Disuse’ and ‘Deconditioning’ in relation to low back pain (LBP) are terms often used interchangeably. Discussions of ‘disuse’ refer to general physical inactivity, which evidence suggests does not differ between symptomatic and asymptomatic persons. ‘Deconditioning’ refers to a decrease in function, commonly both cardiovascular/aerobic fitness and muscular strength/endurance, again noting little difference. However, examination of decreased function relating specifically to lumbar extensor musculature deconditioning has yet to be examined, corroborating all possible methods. Thus, this review attempts to reappraise the deconditioning hypothesis in LBP, specifically considering lumbar extensor deconditioning. Methods: A literature review was conducted examining both cross-sectional and prospective data on specific lumbar extensor deconditioning and LBP. A narrative approach and ‘snowballing’ style literature search was used involving initial use of PubMed and Google Scholar databases searching up to December 2012. Included were studies utilizing the following three research methods, allowing specific induction of the role of such deconditioning; (1) strength/endurance testing of the isolated lumbar extensor musculature, (2) imaging and histochemical examination of the lumbar extensor musculature, and (3) fatigue testing of the lumbar extensor musculature using electromyography. Results/findings: Despite issues interpreting individual studies due to methods, the majority of evidence suggests LBP is associated with decreased strength/endurance, atrophy, and excessive fatigability of the lumbar extensors. Prospective studies also suggest lumbar extensor deconditioning may be a common risk factor predicting acute low back injury and LBP. Conclusions: The hypothesis of specific lumbar extensor deconditioning as being a causal factor in LBP is presently well supported. It is by no means the only causative factor and further research should more rigorously test this hypothesis addressing the methodological issues highlighted regarding previous studies. However, its role suggests specific exercise may be a worthwhile preventative and rehabilitative approach.

Effect of wearing personal protective clothing and self-contained breathing apparatus on heart rate, temperature and oxygen consumption during stepping exercise and live fire training exercises

Fire fighter breathing apparatus instructors (BAIs) must possess the ability to respond to both the extrinsic stress of a high temperature environment and the intrinsic stress from wearing personal protective equipment (PPE) and self-contained breathing apparatus (SCBA), repeatedly and regularly, whilst training recruits in live fire training exercises (LFTEs). There are few previous investigations on BAIs in hot environments such as LFTEs, since the main research focus has been on regular fire fighters undertaking exercises in temperate or fire conditions at a moderate to high exercise intensity. In this study, the intrinsic cardiovascular stress effects of wearing PPE + SCBA were first investigated using a step test whilst wearing gym kit (control), weighted gym kit (a rucksack weighted to the equivalent of PPE + SCBA) and full PPE + SCBA (weight plus the effects of protective clothing). The extrinsic effects of the very hot environment were investigated in BIAs in LFTEs compared to mock fire training exercises (MFTEs), where the fire was not ignited. There was an increase in heart rate due to the modest workload imposed on the BAIs through carrying out the MFTEs (25.0 (18.7)%) compared to resting. However, when exposed to fire during the LFTEs, heat storage appears to be significant as the heart rate increased by up to 39.8 (±20.1)% over that of the mock LFTEs at temperate conditions. Thus, being able to dissipate heat from the PPE is particularly important in reducing the cardiovascular responses for BAIs during LFTEs.

A randomized controlled trial of limited range of motion lumbar extension exercise in chronic low back pain.

Study Design. Randomized controlled trial. Objective. To compare the effects of full range of motion (ROM) and limited ROM isolated lumbar extension exercise upon full ROM lumbar extension strength, ROM, perceived pain, and disability. Summary of Background Data. Limited ROM is common in chronic low back pain as is lumbar extensor deconditioning. Limited ROM exercise is a common prescription but is yet to be empirically tested. Methods. Males (n = 21) and females (n = 17) with nonspecific chronic low back pain were initially recruited. Participants were randomized to either a full ROM (FullROM) or limited ROM (LimROM) training group or a control group. A total of 24 participants (males: n = 14, females: n = 10) completed the study and were included in analysis. The intervention lasted 12 weeks. FullROM and LimROM groups completed isolated lumbar extension resistance training once per week, performing one set of exercise at 80% of their maximal tested functional torque to failure. FullROM group trained through a full ROM. LimROM group trained through the mid 50% of their full ROM. Full ROM isolated lumbar extension strength, lumbar and standing ROM (Schobers test), perceived pain (visual analogue scale), and disability (Revised Oswestry Disability Index) were measured pre- and postintervention. Results. FullROM and LimROM significantly improved in full ROM lumbar extension strength, perceived pain, and disability compared with the control group. No changes occurred in lumbar or standing ROM. No significant differences were found between either FullROM or LimROM for any outcome measure. Changes in perceived pain and disability met minimal clinically important change values for FullROM (visual analogue scale, −30.3 + 25.76 mm and Oswestry Disability Index, −18.2 + 6.63 patients) and LimROM (visual analogue scale, −16.29 + 10.97 mm and Oswestry Disability Index, −12 + 5.16 patients). Conclusion. The results suggest that both FullROM and LimROM are equally effective in increasing full ROM lumbar extension strength and producing clinically meaningful improvement in perceived pain and disability. Level of Evidence: 2

One lumbar extension training session per week is sufficient for strength gains and reductions in pain in patients with chronic low back pain ergonomics.

Chronic low back pain (CLBP) is the leading cause of absenteeism from the workplace and research into exercise interventions to address this problem is required. This study investigated training frequency for participants with CLBP. Participants either trained once a week (1 × week, n = 31), or twice a week (2 × week, n = 20) or did not (control group, n = 21). Participants were isometric strength tested in weeks 1 and 12 and trained dynamically either 1×week (80% of maximum) or 2×week (80% and 50%). The results (pre vs. post) showed significant increases in maximal strength, range of motion and reductions in pain for both training groups. Pain scores for the 1 × week and 2 × week both reached minimal clinical improvement change unlike the control group. Thus, one lumbar extension training session per week is sufficient for strength gains and reductions in pain in low back pain in CLBP patients. Practitioner Summary: CLBP is the leading cause of absenteeism from the workplace. The present study using a modified randomised control trial design investigated exercise training frequency for participants with CLBP. One lumbar extension training session per week is sufficient for strength gains and reductions in low back pain in CLBP patients.

A Review of the Clinical Value of Isolated Lumbar Extension Resistance Training for Chronic Low Back Pain

Chronic low back pain (CLBP) is prevalent, costly, and acknowledged as multifactorial in nature. However, deconditioning of the lumbar extensor musculature may be a common factor. Thus specific resistance exercise is often recommended. Many resistance exercises for the lumbar extensors exist, although recent evidence suggests that isolated lumbar extension (ILEX) resistance training may best for conditioning these muscles. Thus this review aimed to examine the use of ILEX resistance training in participants with CLBP to provide a best‐evidence synthesis for practitioners and clinicians.

Interactive mobile learning: a pilot study of a new approach for sport science and medical undergraduate students

Mobile learning has increasingly become interwoven into the fabric of learning and teaching in the United Kingdom higher education sector, and as technological issues become addressed, this phenomena has accelerated. The aim of the study was to examine whether learning using a mobile learning device (Samsung NC10 Netbook) loaded with interactive exercises promoted learning compared with a traditional library exercise. Using a randomized trial, 55 students from an undergraduate sports science course (n = 28) and medical course (n = 27) volunteered to participate in this study. A mixed-model design ANOVA was used to examine the percent change in test score after a 3-wk intervention. Results showed that there was a significant difference between the two courses (P < 0.001), methods (P = 0.01), and trials (P < 0.001). The findings suggested that both methods augmented student knowledge and understanding in sports science and medical students. The sports science group demonstrated proportionally greater increases in test performance when exposed to the mobile interactive intervention compared with the traditional library approach. Qualitative data suggest an increased level of engagement with the Netbooks due to the stimulating interactive content. In conclusion, the Netbooks were an effective additional learning tool, significantly enhancing knowledge and understanding in students. Further research should ensure that participants are assessed for preferred learning styles, the subjective task value of expectancy value, and readiness for mobile learning to ascertain if this has an effect on the potential for using mobile learning and interactivity.

Lumbar kinematic variability during gait in chronic low back pain and associations with pain, disability and isolated lumbar extension strength

BACKGROUND Chronic low back pain is a multifactorial condition with many dysfunctions including gait variability. The lumbar spine and its musculature are involved during gait and in chronic low back pain the lumbar extensors are often deconditioned. It was therefore of interest to examine relationships between lumbar kinematic variability during gait, with pain, disability and isolated lumbar extension strength in participants with chronic low back pain. METHODS Twenty four participants with chronic low back pain were assessed for lumbar kinematics during gait, isolated lumbar extension strength, pain, and disability. Angular displacement and kinematic waveform pattern and offset variability were examined. FINDINGS Angular displacement and kinematic waveform pattern and offset variability differed across movement planes; displacement was highest and similar in frontal and transverse planes, and pattern variability and offset variability higher in the sagittal plane compared to frontal and transverse planes which were similar. Spearmans correlations showed significant correlations between transverse plane pattern variability and isolated lumbar extension strength (r=-.411) and disability (r=.401). However, pain was not correlated with pattern variability in any plane. The r(2) values suggested 80.5% to 86.3% of variance was accounted for by other variables. INTERPRETATION Considering the lumbar extensors role in gait, the relationship between both isolated lumbar extension strength and disability with transverse plane pattern variability suggests that gait variability may result in consequence of lumbar extensor deconditioning or disability accompanying chronic low back pain. However, further study should examine the temporality of these relationships and other variables might account for the unexplained variance.

Optimal Recovery Time for Postactivation Potentiation in Professional Soccer Players

Abstract Mola, JN, Bruce-Low, SS, and Burnet, SJ. Optimal recovery time for postactivation potentiation in professional soccer players. J Strength Cond Res 28(6): 1529–1537, 2014—Resistance exercise may acutely enhance muscle contractile activity, which is known as postactivation potentiation (PAP). Postactivation potentiation augments important skills that require power production that are necessary during soccer performance. The aim of this study was to determine the optimal recovery time to elicit PAP after a bout of high-intensity resistance exercise in professional soccer players. Twenty-two senior professional soccer players (mean [SD]; age, 23 [4.5] years; stature, 1.83 [6.6] m; body mass, 80.9 [7.8] kg) were randomized to either an experimental (n = 11) or a control group (n = 11). Both groups performed a standardized warm-up and baseline countermovement jump (CMJ) followed by a 10-minute recovery. The control group then performed a CMJ at 15 seconds and at 4, 8, 12, 16, and 20 minutes, whereas the experimental group performed a 3 repetition maximum (RM) squat and then an identical CMJ protocol. No significant differences were found between the groups for CMJ peak power (p > 0.05) or jump height (p > 0.05). No time effect for peak power (F(6,60) = 2.448; p = 0.063) or jump height (F(6,60) = 2.399; p = 0.089) was observed throughout the experimental group trials. Responders (n = 6) displayed individualized PAP profiles at 4 (n = 3), 12 (n = 1), and 16 (n = 2) minutes after conditioning contraction, whereas nonresponders (n = 5) did not. A set of 3RM squats failed to acutely potentiate all participants CMJ performance. Both PAP responders and nonresponders were identified and have individualized PAP time constants. This is not consistent with the previous literature, which used identical protocols. Strength and conditioning practitioners need to individualize recovery “windows” and identify athletes who respond to PAP before undertaking a complex training intervention.