The Effect of Tai Chi on Dynamic Balance in Younger Adults: Implication for Physical Therapy Practice

Purpose: The objective of this study was to investigate the effect of Tai Chi on the dynamic balance in younger, active community-based adults with no history of lower extremity injury or balance problems. Methods: Fourteen subjects (4 males / 10 females; age 23.6 + 6.2 years-old; height 166.5 ± 11.1 cm; weight 75.9 ± 19.3 kg) completed a 13-week undergraduate Tai Chi course. Dynamic balance was assessed at the beginning and the end of the course using the Y-Balance test. Results: Post-hoc testing showed significant improvements in anterior (P=0.007) and posterior lateral (P=0.003) reach distances with a Cohen’s d at 0.54 and 0.71 for the anterior and posterior lateral, respectively with significant improvement in right composite compared to left composite (P\u3c0.0001). Cohen’s d was 0.51 and 1.38 for the left and right composite score, respectively. Conclusions: These findings suggest that Tai Chi may be useful as an exercise regimen to increase anterior and posterior lateral dynamic balance in balance-dependent activity as measured by the Y Balance Test. The authors champion that Tai Chi may be a useful addition for a physical therapy treatment plan, preventative exercise plan, or wellness program to increase anterior and posterior lateral dynamic balance

Electromyographic Analysis of Hip Rehabilitation Exercises in a Group of Healthy Subjects

Study Design Single-occasion, repeated-measures design. Objective To determine the magnitude of hip abductor muscle activation during 6 rehabilitation exercises. Background Many researchers have reported that hip strengthening, especially of the hip abductors, is an important component of a lower extremity rehabilitation program. Clinicians employ non-weight-bearing and weight-bearing exercise to strengthen the hip musculature; however, researchers have not examined relative differences in muscle activation during commonly used exercises. Information regarding these differences may provide clinicians with a scientific rationale needed for exercise prescription. Methods and Measures Sixteen healthy subjects (mean ± SD age, 27 ± 5 years; range, 18–42 years; mean ± SD height, 1.7 ± 0.2 m; mean ± SD body mass, 76 ± 15 kg) volunteered for this study. Bipolar surface electrodes were applied to the right gluteus medius muscle. We measured muscle activation as subjects performed 3 non-weight-bearing (sidelying right hip abduction and standing right hip abduction with the hip at 0° and 20° of flexion) and 3 weight-bearing (left-sided pelvic drop and weight-bearing left hip abduction with the hips at 0° and 20° of flexion) exercises. Data were expressed as a percent of maximum voluntary isometric contraction of the right gluteus medius. Differences in muscle activation across exercises were determined using a 1-way analysis of variance with repeated measures, followed by a sequentially rejective Bonferroni post hoc analysis to identify differences between exercises. Results The weight-bearing exercises demonstrated significantly greater EMG amplitudes (P\u3c.001) than all non-weight-bearing exercises except non-weight-bearing sidelying hip abduction. Conclusion The weight-bearing exercises and non-weight-bearing sidelying hip abduction exercise resulted in greater muscle activation because of the greater external torque applied to the hip abductor musculature. Although the non-weight-bearing standing hip abduction exercises required the least activation, they may benefit patients who cannot safely perform the weight-bearing or sidelying hip abduction exercises. Clinicians may use results from this study when designing hip rehabilitation programs

Reliability of Electromyographic Normalization Methods for Evaluating the Hip Musculature

The purpose of this study was to determine the reliability of three normalization methods for analyzing hip abductor activation during rehabilitation exercises. Thirteen healthy subjects performed three open kinetic chain and three closed kinetic chain hip abductor exercises. Surface EMG activity for the gluteus medius was collected during each exercise and normalized based on a maximum voluntary isometric contraction (MVIC), mean dynamic (m-DYN), and peak dynamic activity (pk-DYN). Intraclass coefficient correlations (ICCs), intersubject coefficients of variation (CVs), and intrasubject CVs were then calculated for each normalization method. MVIC ICCs exceeded 0.93 for all exercises. M-DYN and pk-DYN ICCs exceeded 0.85 for all exercises except for the sidelying abduction exercise. Intersubject CVs ranged from 55% to 77% and 19% to 61% for the MVIC and dynamic methods, respectively. Intrasubject CVs ranged from 11% to 22% for all exercises under all normalization methods. The MVIC method provided the highest measurement reliability for determining differences in activation amplitudes between hip abductor exercises in healthy subjects. Future research should determine if these same results would apply to a symptomatic patient population

Plantar fasciitis and the windlass mechanism: a biomechanical link to clinical practice

Objective: Plantar fasciitis is a prevalent problem, with limited consensus among clinicians regarding the most effective treatment. The purpose of this literature review is to provide a systematic approach to the treatment of plantar fasciitis based on the windlass mechanism model. Data Sources: We searched MEDLINE, SPORT Discus, and CINAHL from 1966 to 2003 using the key words plantar fasciitis, windlass mechanism, pronation, heel pain, and heel spur. Data Synthesis: We offer a biomechanical application for the evaluation and treatment of plantar fasciitis based on a review of the literature for the windlass mechanism model. This model provides a means for describing plantar fasciitis conditions such that clinicians can formulate a potential causal relationship between the conditions and their treatments. Conclusions/Recommendations: Clinicians' understanding of the biomechanical causes of plantar fasciitis should guide the decision-making process concerning the evaluation and treatment of heel pain. Use of this approach may improve clinical outcomes because intervention does not merely treat physical symptoms but actively addresses the influences that resulted in the condition. Principles from this approach might also provide a basis for future research investigating the efficacy of plantar fascia treatment

COMPARISON OF HIP AND KNEE STRENGTH AND NEUROMUSCULAR ACTIVITY IN SUBJECTS WITH AND WITHOUT PATELLOFEMORAL PAIN SYNDROME

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Hip Strength and Hip and Knee Kinematics During Stair Descent in Females With and Without Patellofemoral Pain Syndrome

Study Design Cross-sectional. Objective To determine if females presenting with patellofemoral pain syndrome (PFPS) from no discernable cause other than overuse demonstrate hip weakness and increased hip internal rotation, hip adduction, and knee valgus during stair descent. Background Historically, PFPS has been viewed exclusively as a knee problem. Recent findings have indicated a possible association between hip weakness and PFPS. Researchers have hypothesized that patients who demonstrate hip weakness would exhibit increased hip internal rotation, hip adduction, and knee valgus during functional activities. To date, researchers have not simultaneously examined hip and knee strength and kinematics in subjects with PFPS to make this determination. Methods and Measures Eighteen females diagnosed with PFPS and 18 matched controls participated. Strength measures were taken for the hip external rotators and hip abductors. Hip and knee kinematics were collected as subjects completed a standardized stair-stepping task. Independent t tests were used to determine between-group differences in strength and kinematics during stair descent. Results Subjects with PFPS generated 24% less hip external rotator (P = .002) and 26% less hip abductor (P =. 006) torque. No between-group differences (P\u3e.05) were found for average hip and knee transverse and frontal plane angles during stair descent. Conclusion Subjects with PFPS had significant hip weakness but did not demonstrate altered hip and knee kinematics as previously theorized. Additional investigations are needed to better understand the association between hip weakness and PFPS etiology. Level of Evidence Symptom Prevalence, Level 4

Reliability of Electromyographic Methods Used for Assessing Hip and Knee Neuromuscular Activity in Females Diagnosed with Patellofemoral Pain Syndrome

Patellofemoral pain syndrome (PFPS) is one of the most common, yet misunderstood, knee pathologies. PFPS is thought to result from abnormal patella tracking caused from altered neuromuscular control. Researchers have investigated neuromuscular influences from the gluteus medius (GM), vastus medialis (VM), and vastus lateralis (VL) but with inconsistent findings. A reason for these discrepancies may be from varying methodology. The purpose of this study was to determine the reliability of electromyographic (EMG) methods used to assess amplitudes and timing differences of the GM, VM, and VL in subjects with PFPS. Seven females with PFPS participated. GM, VM, and VL activity was assessed during the stance phase of a stair descent task on two separate occasions. Amplitudes during the different intervals of stance were recorded and expressed as a percent of each muscle’s maximum voluntary isometric contraction. Muscle onsets at the beginning of stair descent were also determined. VM–GM, VL–GM, and VL–VM onset timing differences were quantified. Intraclass correlation coefficients (ICCs) and standard errors of measurement (SEMs) were calculated to assess between-day reliability. Most EMG measures had acceptable reliability (ICC3,5 ⩾ 0.70). Although some measures had moderate reliability (ICC \u3c 0.70), they had low SEMs, which suggested high measurement precision. These findings support using these methods for examining neuromuscular activity in subjects with PFPS