Steven F. Sawyer

Effects of tai chi exercise on posturography, gait, physical function and quality of life in postmenopausal women with osteopaenia: a randomized clinical study

Objective: To evaluate the effects of tai chi exercise on risk factors for falls in postmenopausal women with osteopaenia through measurements of balance, gait, physical function and quality of life. Design: A randomized, controlled, single-blinded, 24-week trial with stratification by age and bone mass. Setting: General community. Participants: Sixty-one independently living elderly females aged 65 years and older with low bone mass. Interventions: Subjects were recruited and randomly assigned to 24 weeks of tai chi (60 minutes/session, three sessions/week, n = 30) or a control group (n = 31). Outcome measures: Computerized dynamic posturography, gait, ‘timed up and go’, five-chair sit-to-stand and quality of life assessed at baseline, 12 and 24 weeks. Results: After 24 weeks, subjects in the tai chi group demonstrated an increase in stride width (P = 0.05) and improvement in general health (P = 0.008), vitality (P = 0.02) and bodily pain (P = 0.03) compared with those in the control group. There was no significant difference in balance parameters, ‘timed up and go’, five-chair sit-to-stand and other domains of quality of life. Conclusion: Tai chi exercise may reduce risk factors for falls by increasing the stride width, and may improve quality of life in terms of general health, vitality and bodily pain in postmenopausal women with osteopaenia.

2006 Young Investigator Award Winner: lumbosacral nerve root displacement and strain: part 2. A comparison of 2 straight leg raise conditions in unembalmed cadavers.

Study Design. An inferential cadaveric study. Objectives. To compare the displacement and strain of the lumbosacral nerve roots during different conditions of straight leg raise (SLR) with intact foraminal ligaments. Summary of Background Data. Clinicians use sensitizing movements such as dorsiflexion during neurodynamic testing, assuming that these prepositions influence the displacement or strain to the lumbosacral nerve roots. Little is known about the effect of these prepositions on neurodynamic behavior. Methods. Lower limbs and associated nerve roots of 5 unembalmed cadavers (n = 10) were used to evaluate the displacement and strain of the L4, L5, and S1 roots during 2 different SLR conditions. Fluoroscopic images of intraneural metal markers were digitized to evaluate displacement and strain during SLR with no preposition (SLR NPP) of the ankle and SLR with dorsiflexion preposition (SLR DF) of the ankle, respectively. Results. SLR NPP produced larger distal displacement at L5 and S1, (P < 0.001) when compared with SLR DF. Displacement comparisons at L4 were nonsignificant (P = 0.051). While nonsignificant, medium to large effect sizes (0.60–0.96) suggest that SLR DF may produce more strain than the SLR NPP condition. Conclusions. Prepositions of the SLR test alter the displacement and possibly the strain of the lumbosacral nerve roots in the lateral recess.

2006 young investigator award winner : Lumbosacral nerve root displacement and strain Part 1. A novel measurement technique during straight leg raise in unembalmed cadavers

Study Design. A descriptive cadaveric study incorporating a novel nerve root marking technique. Objectives. To describe the displacement and strain of the lumbosacral nerve roots in the lateral recess during straight leg raise (SLR) without disrupting the foraminal ligaments. Summary of Background Data. Previous studies document 2 to 8 mm of lumbosacral nerve root displacement during SLR. Prior dissection methods incorporated laminectomy and facetectomy. Methods. Lower limbs and associated nerve roots of 5 unembalmed cadavers (n = 10) were studied. Metal markers were inserted intraneurally within the lateral recess of L4, L5, and S1 with a modified spinal needle. Fluoroscopic images were digitized to evaluate displacement and strain during SLR. Results. The lumbosacral nerve roots in the lateral recess moved less and experienced less strain during SLR than described in previously published reports. Statistically significant distal displacement occurred at hip positions greater than 60° of flexion at all nerve root levels (P < 0.01). Conclusions. The lumbosacral nerve roots (L4, L5, S1) moved less and underwent less strain during SLR testing than previously reported and may require hip motion greater than 60° to produce substantive displacement in the lateral recess. Additional research is needed to examine the effects of prepositioning during SLR.

The double crush syndrome: a common occurrence in cyclists with ulnar nerve neuropathy-a case-control study.

Objective:To evaluate the incidence of double crush syndrome in the upper limbs of cyclists with clinical diagnosis of ulnar nerve neuropathy. Design:Case-control study. Setting:Outpatient clinics and university setting. Participants:Consecutive sampling of 70 cyclists (140 upper limbs) with a mean age of 36 years (±11.3). Seventy-two upper limbs were excluded, leaving 40 upper limbs with a clinical diagnosis of ulnar nerve neuropathy [ULNN (+)] and 28 without symptoms of ulnar nerve neuropathy [ULNN (−)]. Assessment:Cyclists were examined clinically for the presence of proximal dysfunction using the following testing (independent variables): (1) thoracic outlet syndrome provocation testing: elevated arm stress test and modified Cyriax release test; (2) presence of an elevated first rib: cervical rotation lateral flexion test; and (3) presence of proximal symptoms: reports of neck pain and shoulder pain. Main Outcome Measurements:The upper limbs of cyclists were categorized into 2 groups (dependent variable)-ULNN (+) and ULNN (−)-based on history, symptoms, motor, sensory, and provocative clinical testing. Results:A significantly greater number of upper limbs of cyclists with ULNN (+) presented with positive provocative testing for thoracic outlet syndrome (elevated arm stress test P = 0.005; modified Cyriax release test P = 0.002) than did the upper limbs of cyclists with ULNN (−). The likelihood for the presence of neck pain, shoulder pain, and an elevated first rib was 3, 5, and 12 times greater, respectively, in the ULNN (+) than the ULNN (−) group. Conclusion:A statistically significant greater number of the upper limbs of cyclists with clinical diagnosis of ulnar nerve neuropathy presented with proximal dysfunctions suggestive of double crush syndrome.

Analysis of Variance: The Fundamental Concepts

Abstract Analysis of variance (ANOVA) is a statistical test for detecting differences in group means when there is one parametric dependent variable and one or more independent variables. This article summarizes the fundamentals of ANOVA for an intended benefit of the clinician reader of scientific literature who does not possess expertise in statistics. The emphasis is on conceptually-based perspectives regarding the use and interpretation of ANOVA, with minimal coverage of the mathematical foundations. Computational examples are provided. Assumptions underlying ANOVA include parametric data measures, normally distributed data, similar group variances, and independence of subjects. However, normality and variance assumptions can often be violated with impunity if sample sizes are sufficiently large and there are equal numbers of subjects in each group. A statistically significant ANOVA is typically followed up with a multiple comparison procedure to identify which group means differ from each other. The article concludes with a discussion of effect size and the important distinction between statistical significance and clinical significance.

The Effect of Stretching on Muscle Responses and Postural Sway Responses During Computerized Dynamic Posturography in Women and Men

OBJECTIVE To evaluate the effect of stretching on the parameters of postural sway and on the kinematic variables associated with balance control in women and men. DESIGN Mixed repeated measures design with 2 levels. SETTING Research laboratory. PARTICIPANTS Fifteen women and fifteen men (mean age 23.4+/-2.2). INTERVENTION Two separate sessions of (1) lower extremity stretching and (2) no-stretching, immediately prior to balance testing with simultaneous surface electromyographic (EMG) recordings of muscle responses. MAIN OUTCOME MEASURES EMG latencies and average amplitudes for 4 lower extremity muscles for the preferred stance limb during computerized dynamic posturography (CDP) tests, specifically the Postural Evoked Response Test, Adaptation Test, Motor Control Test, Sensory Organization Test, and Unilateral Stance Test. RESULTS Analyses of variance indicated no significant main effect for stretching and 2 significant main effects for gender for the Motor Control Test (P=.021) and latency of tibialis anterior (P=.009). Analyses of covariance with covariants of height and active knee extension revealed no significant main effect of stretching or of gender on muscles responses or CDP performance. CONCLUSIONS In both women and men, lower extremity stretching did not significantly affect muscle responses or performance during CDP.

Association of disturbances in the thoracic outlet in subjects with carpal tunnel syndrome: a case-control study.

INTRODUCTION A limited amount of research has investigated the potential relationship between carpal tunnel syndrome (CTS) and thoracic outlet dysfunction. PURPOSE OF THE STUDY To compare the prevalence of positive clinical tests suggestive of disputed neurogenic thoracic outlet syndrome (TOS) in subjects with CTS (CTS+) with that of subjects without CTS (control). STUDY DESIGN Case-control study. METHODS Subjects with electrodiagnostically confirmed CTS (CTS+) were recruited consecutively and matched by age (±2 years) and gender with asymptomatic (control) subjects. Subjects underwent clinical testing for neurogenic TOS using two provocative tests: modified Cyriax release test and elevated arm stress test (EAST). Subjects were tested for the presence of an elevated first rib using cervical rotation lateral flexion (CRLF) test. RESULTS A total of 32 investigational subjects and 32 matched control subjects was included in each group (mean age: 43.5+5.9 years). A significantly greater number of CTS+ subjects presented with positive provocative testing for TOS (modified Cyriax release test p=0.005; EAST approached significance p=0.027) and for the presence of an elevated first rib (CRLF test p=0.003) as compared with controls. The likelihood of neck pain, shoulder pain, or an elevated first rib was 16 times greater in the CTS+ group as compared with that in the control group. CONCLUSIONS A greater number of subjects with CTS presented with proximal dysfunctions suggestive of TOS and history of neck and shoulder pain. Evaluation of proximal structures involved with thoracic outlet dysfunction in persons with CTS has clinical merit. LEVEL OF EVIDENCE Level III-b.

Rate of False Positive Using the Cyriax Release Test for Thoracic Outlet Syndrome in an Asymptomatic Population

Abstract The purpose of this study was to determine the rate of false positive findings during the Cyriax Release Test for Thoracic Outlet Syndrome (TOS) in an asymptomatic population. The 119 subjects (238 shoulder girdles) with a mean age of 36.3 years included in the study were asked to report any symptoms noted at 1, 3, 5, 10 and 15 minutes of holding the Cyriax Release Test position, which consisted of passive shoulder girdle elevation. Specificity was calculated for each time interval and was highest at 1 minute (97.4%), with a progressive decrease to 77.4% at 15 minutes. Correlation and chi-square analyses were run between demographic data/medical history and positive test results. Neck pain was the only statistically significant variable (p < 0.001). The high specificity of the Cyriax Release Test at 1 and 3 minutes justifies its continued use in clinical setting for the diagnosis of Thoracic Outlet Syndrome.

Effects of Volitional Spine Stabilization and Lower Extremity Fatigue on Trunk Control During Landing in Individuals With Recurrent Low Back Pain

STUDY DESIGN Controlled laboratory study. BACKGROUND Recurrent low back pain (LBP) and neuromuscular fatigue are independently thought to increase the risk of spine injury. Volitional preemptive abdominal contraction (VPAC) is thought to improve lumbar spine and pelvis control in individuals with recurrent LBP. The effects of VPAC on fatigued landing performance in individuals with recurrent LBP are unknown. OBJECTIVES To determine the effects of VPAC and lower extremity fatigue on trunk control during landing in a population of individuals with recurrent LBP. METHODS Thirty-two recurrent LBP (mean ± SD age, 21.2 ± 2.7 years) and 33 healthy (age, 20.9 ± 2.3 years) subjects performed 0.30-m drop-jump landings with and without VPAC and fatigue. Trunk, pelvis, and hip biomechanical and electromyographic variables were obtained using 3-D motion capture. Hypotheses were tested using analysis of variance. RESULTS Volitional preemptive abdominal contraction resulted in significantly earlier muscle onsets across all muscles, with and without fatigue, in both groups (mean ± SD, 0.058 ± 0.019 seconds earlier; P≤.001) and altered lumbar lateral flexion (1.4° ± 14.8° greater right lateral flexion; P = .002). Fatigue significantly delayed muscle onsets (0.040 ± 0.014 seconds later; P≤.001) and altered pelvic obliquity (1.4° ± 11.0° greater; P≤.001) and trunk side flexion (2.0° ± 14.8° less; P≤.001). The recurrent LBP group exhibited delayed muscle onsets (0.039 ± 0.031 seconds later; P≤.004) and 4.2° less hip abduction at initial contact (P≤.008) in comparison to healthy controls. CONCLUSION Volitional preemptive abdominal contraction decreases some of the detrimental effects of fatigue on landing biomechanics and thus may reduce spine injury risk in individuals with recurrent LBP.

Effects of Volitional Spine Stabilization and Lower Extremity Fatigue on Knee and Ankle during Landing Performance in a Recurrent Low Back Pain Population

INTRODUCTION Recurrent lower back pain (rLBP) and neuromuscular fatigue are independently thought to increase the risk of lower extremity (LE) injury. Volitional preemptive abdominal contraction (VPAC) is thought to improve lumbar spine and pelvis control in individuals with rLBP. The effects of VPAC on fatigued landing performance in individuals with rLBP are unknown. OBJECTIVES To determine the effects of VPAC and LE fatigue on landing performance in a rLBP population. DESIGN Cross-sectional pretest-posttest cohort control design. SETTING A clinical biomechanics laboratory. SUBJECTS 32 rLBP (age 21.2 ± 2.7 y) but without current symptoms and 33 healthy (age 20.9 ± 2.3 y) subjects. INTERVENTION(S) (i) Volitional preemptive abdominal contraction using abdominal bracing and (ii) fatigue using submaximal free-weight squat protocol with 15% body weight until task failure was achieved. MAIN OUTCOME MEASURE(S) Knee and ankle angles, moments, electromyographic measurements from semitendinosus and vastus medialis muscles, and ground reaction force (GRF) were collected during 0.30 m drop-jump landings. RESULTS The VPAC resulted in significantly earlier muscle onsets across all muscles with and without fatigue in both groups (mean ± SD, 0.063 ± 0.016 s earlier; P ≤ .001). Fatigue significantly delayed semitendinosus muscle onsets (0.033 ± 0.024 s later; P ≤ .001), decreased GRF (P ≤ .001), and altered landing kinematics in a variety of ways. The rLBP group exhibited delayed semitendinosus and vastus medialis muscle onsets (0.031 ± 0.028 s later; P ≤ .001) and 1.8° less knee flexion at initial contact (P ≤ .008). CONCLUSION The VPAC decreases some of the detrimental effects of fatigue on landing biomechanics and thus may reduce LE injury risk in a rLBP population.