Research Report
Tracy A. Dierks, Kurt T. Manal, Joseph Hamill, Irene S. Davis
STUDY DESIGN: Experimental correlation study. OBJECTIVES: To investigate the relationships between hip strength and hip kinematics, and between arch structure and knee kinematics during prolonged treadmill running in runners with and without patellofemoral pain syndrome (PFPS). BACKGROUND: Hip weakness can lead to excessive femoral motions that adversely affect patellofemoral joint mechanics. Similarly, foot mechanics, which are influenced by foot structure, are also known to influence patellofemoral joint mechanics. Thus, proximal and distal factors should be considered when studying individuals with PFPS. METHODS AND MEASURES: Twenty recreational runners with PFPS (5 male, 15 female) and 20 matched uninjured runners participated in the study. Hip abduction and hip external rotation isometric strength measurements were collected before and after a prolonged run, while the arch height index was recorded on all runners before the run. Lower extremity kinematic data were collected at the beginning and end of the run. Two-way repeated measures ANOVAs were used for analysis. RESULTS: Both groups displayed decreases in hip abductor and external rotator strengths at the end of the run. The PFPS group displayed significantly lower hip abduction strength (kg*cm/body weight) compared to controls (PFPS begin 15.3, end 13.5; uninjured begin 17.3, end 15.4). At the end of the run, the level of association between hip abduction strength and the peak hip adduction angle for the PFPS group was statistically significant indicating a strong relationship (r = -0.74). No other associations with hip strength were observed in either group. Arch height did not differ between groups and no significant association was observed between arch height and peak knee adduction angle during running. CONCLUSIONS: Runners with PFPS displayed weaker hip abductor muscles that were associated with an increase in hip adduction during running. This relationship became more pronounced at the end of the run.
J Orthop Sports Phys Ther., Epub 15 April 2008. doi:10.2519/jospt.2008.2490
KEY WORDS: arch height index, hip abductor muscle strength, hip external rotator muscle strength, knee valgus
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Research Report
Yusaku Sugiura, Tomoyuki Saito, Keishoku Sakuraba, Kazuhiko Sakuma, Eiichi Suzuki
STUDY DESIGN: Prospective cohort study. OBJECTIVES: In this prospective cohort study of elite sprinters, muscle strength of the hip extensors, as well as of the knee extensors and flexors was measured to determine a possible relationship between strength deficits and subsequent hamstring injury within 12 months of testing. The method used for testing muscle strength simulated the specific muscle action during late swing and early contact phases when sprinting. BACKGROUND: There have been no prospective studies in elite sprinters that examined the concentric and eccentric isokinetic strength of the hip extensors and the quadriceps and hamstring muscles in a manner that reflects their actions in late swing or early contact phases of sprinting. Consequently, the causal relationship between hip and thigh muscle strength and hamstring injury in elite sprinters may not be fully understood. METHODS AND MEASURES: Isokinetic testing was performed on 30 male elite sprinters to assess hip extensors, quadriceps, and hamstring muscle strength. The occurrence of hamstring injury among the subjects was determined during the year following the muscle strength measurements. The strength of the hip extensors, quadriceps, and hamstring muscles, as well as the hamstrings/quadriceps (H/Q) and hip extensors/quadriceps ratios were compared. RESULTS: Hamstring injury occurred in 6 subjects during the 1-year period. Isokinetic testing at a speed of 60 deg/sec revealed weakness of the injured limb with eccentric action of the hamstring muscles and during concentric action of the hip extensors. When performing a side to side comparison for the injured sprinters, the hamstring injury always occurred on the weaker side. Differences in the H/Q and hip extensors/quadriceps strength ratios were also evident between uninjured and injured limbs and this was attributable to deficits in hamstring strength. CONCLUSION: Hamstring injury in elite sprinters was associated with weakness during eccentric action of the hamstrings and weakness during concentric action of the hip extensors, but only when tested at the slower speed of 60 deg/sec.
J Orthop Sports Phys Ther., Epub 15 April 2008. doi:10.2519/jospt.2008.2575
KEY WORDS: isokinetics, quadriceps, running, sprinting
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Research Report
Kerrie Evans, Kathryn M. Refshauge, Roger D. Adams, Rod Barrett
STUDY DESIGN: Laboratory experimental study consisting of pre and post intervention measurements. OBJECTIVE: To determine the effects of a putting practice session on the kinematics of full golf swings made by skilled male golfers. BACKGROUND: Skilled golfers perform putting practice for prolonged periods. The combination of sustained trunk flexion with minimal trunk motion may affect the endurance capacity of the trunk extensor muscles. Because of their important role in the golf swing, any impairment of the trunk extensors may negatively influence full-swing kinematics, but this has not been previously evaluated. METHODS AND MEASURES: Three-dimensional swing kinematics, and holding time on the Biering-Sørensen test of isometric trunk extensor endurance, were evaluated in 29 skilled male golfers before and after performing a 40 minute putting task. RESULTS: After the intervention, peak segmental speeds were reduced and total swing duration increased (mean ± SD, 36 ± 55 milliseconds). There were reductions in the magnitude of pelvis and torso axial rotation during the downswing (mean ± SD, -2.3 ± 2.6° and -2.3 ± 4.7°, respectively). The peak difference between torso rotation and pelvis rotation during early downswing was also significantly reduced by 0.9 ± 2.0° (P < 0.05). The effects on pelvis and torso rotation were smallest for golfers with higher body mass index (BMI). Holding time on the Biering-Sørensen test after putting practice was significantly reduced by 25.7 ± 23.8 seconds. CONCLUSION: Changes in swing kinematics observed following 40 minutes of putting practice may have resulted from fatigue-related impairment of the trunk extensor muscles, a view supported by the poorer performance on the post-intervention Biering-Sørensen test. Results showed that swing kinematics of golfers with high BMI were least affected by the putting practice.
J Orthop Sports Phys Ther., Epub 15 April 2008. doi:10.2519/jospt.2008.2617
KEY WORDS: erector spinae, golf, lumbar spine
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Research Report
Ashraf S. Gorgey, Gary A. Dudley
STUDY DESIGN: Controlled laboratory study OBJECTIVES: To determine the effects of pulse durations and stimulation durations on the evoked torque after controlling for the activated area by using magnetic resonance imaging (MRI). BACKGROUND: Neuromuscular electrical stimulation (NMES) is commonly used in the clinic without considering the physiological implications of its parameters. METHODS AND MEASURES: Seven able-bodied, college students (mean +/- SD age = 28 +/- 4 years) participated in this study. Two NMES protocols were applied to the knee extensor muscle group in a random order. Protocol A was 100 Hz, 450 µs pulses applied for 5 minutes in a 3 sec on 3 sec off duty cycle. Protocol B was 60 Hz, 250 µs pulses applied for 5 minutes in a10 sec on 20 sec off duty cycle. The amplitude of the current was similar in both protocols. Torque, torque time integral, and normalized torque for the knee extensors were measured for both protocols. MRI scans were taken prior to and immediately post each protocol to measure the cross-sectional area (CSA) of the stimulated muscle. RESULTS: The skeletal muscle CSA activated after both protocols were similar. The longer pulse duration in protocol A elicited 22% greater torque output than protocol B (P < .05). After considering the activated area in both protocols, the normalized torque with protocol A was 38% greater than with protocol B (P < .05). Torque-time integral was 21% greater with protocol A (P = .029). Protocol B fails to maintain torque at the start and the end of the 10 sec contraction. CONCLUSIONS: Longer pulse duration, but not contraction time, resulted in a greater evoked and normalized torque compared to the shorter pulse duration even after controlling for the activated muscular CSA with both protocols.
J Orthop Sports Phys Ther., Epub 25 April 2008. doi:10.2519/jospt.2008.2734
KEY WORDS: electrotherapy, MRI, NMES, quadriceps
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Research Report
Teresa SM. Yeung, Jean Wessel, Paul W. Stratford, Joy C. MacDermid
STUDY DESIGN: Single group repeated measures study. OBJECTIVE: To examine the test-retest reliability of the Time Up and Go (TUG) test and its validity for measuring change and predicting length of stay (LOS) on an inpatient orthopaedic rehabilitation ward. BACKGROUND: The TUG test is used to measure functional mobility of persons with musculoskeletal conditions but it has not been thoroughly tested for use in an inpatient orthopaedic rehabilitation ward. METHODS AND MEASURES: The TUG test was administered to 142 patients on admission to an orthopaedic rehabilitation ward, 7-10 days after admission, and on discharge. To test reliability, 24 subjects had these tests repeated 1 day after admission, and the intraclass correlation (ICC) and standard error of measurement (SEM) were calculated. Change scores of the TUG test were evaluated against change scores in pain and function, and the patient's and therapist's rating of improvement. The standardized response mean (SRM) was also calculated. A regression analysis was performed to determine whether the admission TUG test score could predict LOS. RESULTS: The ICC of the TUG test was 0.80, and the SEM 10.2 seconds. The change in TUG test scores correlated with the changes in pain (r=0.21, P<.01) and function (r=-0.23, P<.01) and resulted in an SRM of 0.89 for subjects rated as improved. The admission TUG test scores accounted for only 3.4% of the variance in inpatient LOS. CONCLUSION: The TUG test is reliable and valid to assess group change of inpatients on an orthopaedic rehabilitation ward, but is not a good predictor of LOS.
J Orthop Sports Phys Ther., Epub 22 February 2008, doi:10.519/jospt.2008.2657
KEY WORDS: joint replacement, length of stay, outcome measure, TUG test
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Research Report
Shawn Farrokhi, Christine D. Pollard, Richard B. Souza, Yu-Jen Chen, Stephen Reischl, Christopher M. Powers
STUDY DESIGN: Experimental laboratory study. OBJECTIVES: To examine how a change in trunk position influences the kinematics, kinetics, and muscle activity of the lead lower extremity during the forward lunge exercise. BACKGROUND: Altering the position of the trunk during the forward lunge exercise is thought to affect the muscular actions of the lead lower extremity. However, no studies have compared the biomechanical differences between the traditional forward lunge and its variations. METHODS AND MEASURES: Ten healthy adults (5 males, 5 females; mean age ± SD, 26.7 ± 3.2 years) participated. Lower extremity kinematics, kinetics, and surface electromyographic (EMG) data were obtained while subjects performed 3 lunge exercises: normal lunge with the trunk erect (NL), lunge with the trunk forward (LTF), and lunge with trunk extension (LTE). A 1-way analysis of variance with repeated measures was used to compare lower extremity kinematics, joint impulse (area under the moment-time curve), and normalized EMG (highest 1-second window of activity for selected lower extremity muscles) among the 3 lunge conditions. RESULTS: During the LTF condition, significant increases were noted in peak hip flexion angle, hip extensor and ankle plantar flexor impulse, as well as gluteus maximus and biceps femoris EMG (P< 0.015) when compared to the NL condition. During the LTE condition, significant increases were noted only in peak ankle dorsiflexion and peak hip flexion angles (P< 0.015) compared to the NL condition. CONCLUSIONS: Performing a lunge with the trunk forward increased the hip extensor impulse and the recruitment of the hip extensors. In contrast, performing a forward lunge with the trunk extended did not alter joint impulse or activation of the lower extremity musculature.
J Orthop Sports Phys Ther., Epub 15 April 2008. doi:10.2519/jospt.2008.2634
KEY WORDS: biomechanics, EMG, impulse, weight-bearing
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