Hsing-Kuo Wang

Isokinetic performance and shoulder mobility in elite volleyball athletes from the United Kingdom

Objectives—To evaluate the differences in strength and mobility of shoulder rotator muscles in the dominant and non-dominant shoulders of elite volleyball players. Methods—Isokinetic muscle strength tests were performed at speeds of 60 and 120°/s, and shoulder mobility was examined in ten players from the England national mens volleyball squad. The subjects also completed a questionnaire that included a visual prompt and analogue pain scale. Results—The range of motion of internal rotation on the dominant side was less than that on the non-dominant side (p<0.01). The average peak strength at 60°/s external eccentric contraction was lower than that of internal concentric contraction in the dominant arm, but was higher in the non-dominant arm. Six of the ten subjects reported a shoulder problem, described as a diffuse pain located laterally on the dominant shoulder. Conclusions—These elite volleyball players had a lower range of motion (internal rotation) and relative muscle imbalance in the dominant compared with the non-dominant shoulder.

Relationships between three potentiation effects of plyometric training and performance

This study measured the potentiation effects of plyometric training [normalized electromyography (EMG) in triceps surae, stiffness and elastic energy utilization of the Achilles tendon] and investigated the correlations between these effects and performances [voluntary electromechanical delay (EMD) and jump height]. Twenty‐one subjects were randomly assigned either to the control group (10 subjects: age 22.3±1.6 years) or to a training group (11 subjects: age 22.1±1.6 years) that performed 8 weeks of plyometric training. Results: As compared with the performances before training, normalized EMG in the soleus were significantly (P≤0.001) increased after 4 and 8 weeks of training. Tendon stiffness, elastic energy storage, release and jump height determined after training were significantly increased (P<0.05), with a concomitantly reduced voluntary EMD (P=0.01). These variables also showed significant differences vs the control group (all P<0.05). The other variables remained unchanged. Correlations were observed between tendon stiffness and either voluntary EMD (r=−0. 77, P=0.014) or jump height (r=0.54, P=0.031). Conclusions: Plyometric training specifically potentiated the normalized EMG, tendon stiffness and elastic energy utilization in the myotendinous complex of the triceps surae. Although these changes are possibly essential determinants, only increases of tendon stiffness were observed to correlate with performance improvements.

Ultrasonographic guided botulinum toxin type A treatment for plantar fasciitis: an outcome-based investigation for treating pain and gait changes.

OBJECTIVE To evaluate the effectiveness of ultrasonographic guided botulinum toxin type A injections into the plantar fascia to reduce pain and improve gait in patients with unilateral plantar fasciitis. DESIGN A randomized double-blind control study. SUBJECTS Fifty patients with chronic unilateral plantar fasciitis were recruited, and divided into experimental and control groups. METHODS Subjects in the experimental group were injected with 50 units botulinum toxin type A, reconstituted with normal saline, into the plantar fascia under ultrasonographic guidance. Follow-up evaluations were made 3 weeks and 3 months after injection. The control group subjects were injected with normal saline under ultrasonographic guidance. Outcome measures included comparing scores from the visual analogue pain scale, changes in thickness of the plantar fascia and fat pad, and gait assessment including the maximal centre of pressure velocity during first step loading response. RESULTS Visual analogue pain scale and plantar fascia thickness in the symptomatic foot decreased significantly, as noted at follow-up 3 weeks and 3 months after botulinum toxin type A injections (p < 0.001). However, the fat pad thickness remained unchanged. The centre of pressure velocity during loading response increased 3 months after injection (p < 0.05). Outcome measures of the control group remained unchanged. CONCLUSION Botulinum toxin type A is effective in the treatment of foot pain associated with plantar fasciitis and increases the centre of pressure velocity during loading response without inducing fat pad atrophy.

Psychometric evaluation of the Taiwan version of the Disability of the Arm, Shoulder, and Hand (DASH) questionnaire.

BACKGROUND AND PURPOSE To adapt the Taiwan version of the Disability of the Arm, Shoulder, and Hand (DASH) questionnaire and evaluate its psychometric properties. METHODS The DASH questionnaire was adapted through the process of translation, back-translation, and expert review. Eighty two subjects with upper extremity disorders were recruited in a medical center and 46 of these patients could be followed up to assess retest reliability in less than 10 days. Cronbach alpha and intraclass correlation coefficient were used to evaluate the internal consistency and test-retest reliability. Principal axis factor analysis was performed to assess the factor-construct validity, while concurrent validity was tested with the Medical Outcomes Study Short Form-36 (SF-36) Taiwan version questionnaire. RESULTS The internal consistency of the Taiwan version of the DASH questionnaire was high (Cronbach alpha = 0.96) and the test-retest reliability was satisfactory (intraclass correlation coefficient = 0.9). Principal axis factor analysis confirmed the 1-factor model. The Pearson correlation coefficients of the DASH questionnaire to the SF-36 showed a correlation with physical component summary scores rather than mental component summary scores. Bodily pain, physical function and role-physical scores among the SF-36 subscales were most significantly correlated with DASH disability/symptom scores. CONCLUSION The Taiwan version of the DASH questionnaire is a valid and reliable measure of health status for patients with upper-extremity disorders.

Effects of tendon viscoelasticity in Achilles tendinosis on explosive performance and clinical severity in athletes.

The aim was to compare viscoelastic properties of Achilles tendons between legs in elite athletes with unilateral tendinosis, and to investigate relationships between the properties and explosive performance and clinical severity. Seventeen male athletes (mean ± standard deviation age, 27.3 ± 2.0 years) who had unilateral, chronic middle‐portion tendinopathy of the Achilles tendon were assessed by the Victorian Institute of Sport Assessment questionnaire, measurements of tendon viscoelastic properties, voluntary electromechanical delay (EMD), normalized rate of force development (RFD), and one‐leg hopping distance. Compared with the non‐injured leg, the tendinopathic leg showed reduced tendon stiffness (−19.2%. P < 0.001), greater mechanical hysteresis (+21.2%, P = 0.004), lower elastic energy storage and release (−14.2%, P = 0.002 and −19.1%, P < 0.001), lower normalized RFD at one‐fourth (−16.3%, P = 0.02), 2/4 (−17.3%, P = 0.006), and three‐fourths maximal voluntary contraction (−13.7%, P = 0.02), longer soleus and medial gastrocnemius voluntary EMD (+26.9%, P = 0.009 and +24.0%, P = 0.004), and shorter hopping distances (−34.1%, P < 0.001). Tendon stiffness was correlated with normalized RFD, voluntary EMD in the medial gastrocnemius, and hopping distances (r ranged from −0.35 to 0.64, P < 0.05). Hysteresis was correlated to the soleus voluntary EMD and hopping distances (r = 0.42 and −0.39, P < 0.05). We concluded that altered tendon viscoelastic properties in Achilles tendinosis affect explosive performance in athletes.

Relationship Between Chest Wall Motion and Diaphragmatic Excursion in Healthy Adults in Supine Position

BACKGROUND/PURPOSE There has been a lack of studies that have used both three-dimensional analysis and imaging tools concurrently to describe lung volume changes and breathing pattern in subjects in the supine position. The purpose of this study was to investigate the correlation between volume changes estimated by optoelectronic plethysmography (OEP) and diaphragmatic excursion (DE) measured by ultrasonography of healthy adults in the supine position. METHODS Twelve healthy male subjects (age, 25.08 +/- 6.35 years) were recruited and asked to perform tidal and deep breathing in the supine position. The volume changes during chest wall motion were quantified from OEP analysis---this was done for the upper thorax (UT), lower thorax (LT), and abdominal (AB) compartment. Lung volume was measured synchronously via the mouth piece of an electrospirometer. The right diaphragmatic movement was measured by ultrasonography. RESULTS Linear regression showed that all three compartments (V UT, V LT and V AB) in the inspiratory phase were correlated highly with DE during tidal and deep breathing. However, multiple linear regression analysis showed that the VAB contributed 94-95% of the variance when performing either tidal or deep breathing. A predicted equation for diaphragmatic movement during deep breathing was DE = 0.052 + 0.294 V AB. CONCLUSION The movement of V AB can be used as an index of DE among the normal population in the supine position. Its application in patients requires further study.

Evaluating Displacement of the Coracoacromial Ligament in Painful Shoulders of Overhead Athletes Through Dynamic Ultrasonographic Examination

OBJECTIVE To evaluate displacement of the coracoacromial ligament (CAL), using dynamic ultrasonography (US), for detecting instability-related impingement caused by overhead activities. DESIGN Between-group survey. SETTING Department of Physical Medicine and Rehabilitation in a tertiary care center. PARTICIPANTS Volunteer high school volleyball players with unilateral shoulder pain (n=10) and volunteer asymptomatic high school volleyball players with identical training activities as control subjects (n=16). INTERVENTIONS Not applicable. MAIN OUTCOME MEASURE The displacement of the CAL was measured during throwing simulation using dynamic US. Both shoulders of all subjects were evaluated. RESULTS During throwing simulation, the displacement of the CAL in the painful shoulders of overhead athletes increased significantly greater than the displacement in the asymptomatic shoulder (3.0+/-0.7 mm and 2.2+/-0.4 mm, respectively; P=.017). No difference was identified between the displacements of the CALs of bilateral shoulders of the control group subjects. CONCLUSIONS Dynamic US, by measuring the displacement of the CAL during simulation of throwing, may be helpful in detecting abnormal humeral head upward migration in overhead athletes.

Dynamic visualization of the coracoacromial ligament by ultrasound.

Subacromial impingement syndrome (SIS) is prevalent in athletes who make throwing motions over their heads, as well as in the normal population, but it is difficult to diagnose precisely using physical examination and traditional imaging modalities. Furthermore, the diagnostic testing protocols have not been strictly standardized. We used ultrasound to dynamically visualize coracoacromial ligament (CAL) morphology during shoulder impingement tests: the CAL is the key impinging structure in SIS. Fifty normal shoulders were examined. With the transducer placed on the CAL, the shoulders were examined with seven different testing protocols described in the literature. The degree of CAL bulge from the resting position was measured, and the degree of bulge in different testing protocols was compared. We found that the Hawkins-Kennedy impingement test caused more CAL bulge than the Neers impingement test, and the most prominent morphological change in the CAL occurred with an internally rotated and horizontally abducted shoulder. We conclude that high-resolution ultrasound is an excellent tool for dynamically inspecting the impinging structures, is applicable in clinical settings, and allows more accurate diagnosis of SIS.

Noninvasive analysis of fascicle curvature and mechanical hardness in calf muscle during contraction and relaxation.

The purpose of this study was to investigate whether changes of fascicle curvature and muscle hardness of the gastrocnemius muscle during relaxation and isometric contraction could be measured using a noninvasive approach. Seventeen male college students (age 21.0+/-1.5 years) participated in this study. Measurements were made during the resting state and maximal isometric plantarflexion. Fascicle curvature (m(-1)) of the gastrocnemius medialis was measured by ultrasonography. Muscle hardness (kg/mm) was measured with a myotonometer. Angle of ankle joint (degrees), amplitude of electromyographic activities (mV), and plantarflexion force (kg) were simultaneously recorded using an electrogoniometer, surface electromyography (EMG), and a load cell, respectively. Results demonstrated that the joint angle, electromyographic activities, and force at muscle contraction for the myotonometer and ultrasound conditions were not significantly different (all p>0.05). Hardness and fascicle curvature during maximal isometric plantarflexion were significantly greater than those at rest (p=0.002 and p<0.001, respectively). Correlations between changes in fascicle curvature and changes of muscle hardness that took place between muscle relaxation and maximal contraction were significant (r=0.832, p=0.011). This study demonstrates that ultrasonographic and myotonometric measurements are useful to quantify changes in muscle geometry and mechanical properties for muscles during isometric contraction.

Evoked Spinal Reflexes and Force Development in Elite Athletes With Middle-Portion Achilles Tendinopathy

STUDY DESIGN Controlled laboratory study. OBJECTIVES To compare the neuromuscular function of the triceps surae muscle bilaterally in elite athletes with unilateral chronic Achilles tendinopathy. BACKGROUND Previous studies suggest that tendinopathies or chronic pain may lead to a spinal/supraspinal level modulation of the excitability or voluntary activation of ipsilateral motor units. However, this has not been studied in Achilles tendinopathy. METHODS Fourteen college athletes (mean ± SD age, 24.2 ± 1.7 years) who had unilateral chronic middle-portion tendinopathy in their Achilles tendons were recruited. Bilateral measurements of soleus reflex tests, including H-reflex and V wave, and rate of force development (RFD), as well as corresponding electromyography of the tibialis anterior and triceps surae muscles, were performed. Statistical within-subject and between-leg comparisons were made. RESULTS In the leg with tendinopathy, the V wave of the soleus muscle was significantly increased (P<.001). The side with tendinopathy also had a reduced normalized RFD (0-30, 0-50, and 0-100 ms) in plantar flexion, and concomitant higher electromyography ratios between the tibialis anterior and soleus (0-30 and 0-50 milliseconds) during the early stage of explosive contractions (P<.05). No significant differences were found for H-reflex, maximal plantar flexion and dorsiflexion torque, and absolute RFD. CONCLUSIONS Higher volitional supraspinal reflexes and lower maximal-strength independent force development occur in the triceps surae of elite athletes with unilateral middle-portion Achilles tendinopathy. These changes potentially indicate an acquired compensatory mechanism for maximal force production and deficits in explosive strength. The RFD is also suggested as a sensitive parameter to depict neuromuscular changes during treatment of chronic tendinopathies.