Motor patterns of patients with spinal muscular atrophy suggestive of sensory and corticospinal contributions to the development of locomotor muscle synergies.

Complex locomotor patterns are generated by combination of muscle synergies. How genetic processes, early sensorimotor experiences, and the developmental dynamics of neuronal circuits contribute to the expression of muscle synergies remains elusive. We shed light on the factors that influence development of muscle synergies by studying subjects with spinal muscular atrophy (SMA, types II/IIIa), a disorder associated with degeneration and deafferentation of motoneurons and possibly motor cortical and cerebellar abnormalities, from which the afflicted would have atypical sensorimotor histories around typical walking onset. Muscle synergies of children with SMA were identified from electromyographic signals recorded during active-assisted leg motions or walking, and compared with those of age-matched controls. We found that the earlier the SMA onset age, the more different the SMA synergies were from the normative. These alterations could not just be explained by the different degrees of uneven motoneuronal losses across muscles. The SMA-specific synergies had activations in muscles from multiple limb compartments, a finding reminiscent of the neonatal synergies of typically developing infants. Overall, while the synergies shared between SMA and control subjects may reflect components of a core modular infrastructure determined early in life, the SMA-specific synergies may be developmentally immature synergies that arise from inadequate activity-dependent interneuronal sculpting due to abnormal sensorimotor experience and other factors. Other mechanisms including SMA-induced intraspinal changes and altered cortical-spinal interactions may also contribute to synergy changes. Our interpretation highlights the roles of the sensory and descending systems to the typical and abnormal development of locomotor modules.NEW & NOTEWORTHY This is likely the first report of locomotor muscle synergies of children with spinal muscular atrophy (SMA), a subject group with atypical developmental sensorimotor experience. We found that the earlier the SMA onset age, the more the subjects' synergies deviated from those of age-matched controls. This result suggests contributions of the sensory/corticospinal activities to the typical expression of locomotor modules, and how their disruptions during a critical period of development may lead to abnormal motor modules.

Effectiveness of Balance Exercise and Brisk Walking on Alleviating Nonmotor and Motor Symptoms in People With Mild-to-Moderate Parkinson Disease: A Randomized Clinical Trial With 6-Month Follow-up.

OBJECTIVE: To investigate the effects of balance exercise and brisk walking on nonmotor and motor symptoms, balance and gait functions, walking capacity, and balance confidence in Parkinson disease (PD) at posttraining and 6-month follow-up. DESIGN: Two-arm, assessor-blinded randomized controlled trial SETTING: University research laboratory and the community PARTICIPANTS: Ninety-nine eligible individuals with mild-to-moderate PD INTERVENTIONS: Participants were randomized to balance and brisk walking group (B&B, n=49) or active control group (n=50). B&B received ten 90-minute sessions of balance exercises and brisk walking supervised by physical therapists for 6 months (week 1-6: weekly, week 7-26: monthly), whereas control practiced whole-body flexibility and upper limb strength exercise at same dosage (180 min/wk). Both groups performed unsupervised home exercises 2-3 times/wk during intervention and continued at follow-up. MAIN OUTCOME MEASURES: Primary outcomes were Movement Disorder Society Unified Parkinson Disease Rating Scale nonmotor (MDS-UPDRS-I) and motor (MDS-UPRDS-III) scores. Secondary outcomes were mini-Balance Evaluation Systems Test (mini-BEST) score, comfortable gait speed (CGS), 6-minute walk test (6MWT), dual-task timed-Up-and-Go (DTUG) time, and Activities-Specific Balance Confidence Scale score. RESULTS: Eighty-three individuals completed the 6-month intervention with no severe adverse effects. The mean between-group (95% CI) difference for the MDS-UPDRS nonmotor score was 1.50 (0.19-2.81) at 6 months and 1.09 (-0.66 to 2.85) at 12 months. The mean between-group (95% CI) difference for the MDS-UPDRS motor score was 3.75 (0.69-6.80) at 6 months and 4.57 (1.05-8.01) at 12 months. At 6 and 12 months, there were significant between-group improvements of the B&B group in mini-BEST score, CGS, 6MWT, and DTUG time. CONCLUSIONS: This combined balance and brisk walking exercise program alleviates nonmotor and motor symptoms and improves walking capacity, balance, and gait functions posttraining, with positive carryover effects for all except nonmotor outcomes, at 6-month follow-up in mild-to-moderate PD.

Minimalist school shoes improve intrinsic foot muscle size, strength, and arch integrity among primary school students.

Minimalist walking shoes have been shown to improve foot muscle size and strength in active adults, but not in our previous study involving children, which could relate to the more structured footwear used in our study. Hence, this study examined the effects of true minimalists on intrinsic foot muscle size and strength, foot arch integrity, and physical function among primary school children. After a baseline assessment, 30 primary school students aged between 9 and 12 were given a pair of minimalist shoes (minimalist index = 92%) as their regular school shoes for two school terms, followed by a re-assessment. Seventeen of the 30 participants in the minimalist group completed the study. Compared to the control group, the minimalist group showed significantly increased cross-sectional area of abductor hallucis (p = 0.047, Cohen's d = 0.57) and flexor digitorum brevis (p = 0.037, Cohen's d = 0.80), increased strength of the hallux (p = 0.015, Cohen's d = 0.76) and lesser toes (p = 0.014, Cohen's d = 0.66), greater arch height (p = 0.020, Cohen's d = 0.52) and standing long jump distance (p = 0.001, Cohen's d = 9.79). The control group exhibited improved standing long jump performance only (p = 0.020, Cohen's d = 10.70). Minimalist shoes worn daily to school promote intrinsic foot muscle size and strength, and improve foot arch integrity among primary school students.

Evaluation of a Restoration Algorithm Applied to Clipped Tibial Acceleration Signals.

Wireless accelerometers with various operating ranges have been used to measure tibial acceleration. Accelerometers with a low operating range output distorted signals and have been found to result in inaccurate measurements of peaks. A restoration algorithm using spline interpolation has been proposed to restore the distorted signal. This algorithm has been validated for axial peaks within the range of 15.0-15.9 g. However, the accuracy of peaks of higher magnitude and the resultant peaks have not been reported. The purpose of the present study is to evaluate the measurement agreement of the restored peaks using a low-range accelerometer (±16 g) against peaks sampled using a high-range accelerometer (±200 g). The measurement agreement of both the axial and resultant peaks were examined. In total, 24 runners were equipped with 2 tri-axial accelerometers at their tibia and completed an outdoor running assessment. The accelerometer with an operating range of ±200 g was used as reference. The results of this study showed an average difference of -1.40 ± 4.52 g and -1.23 ± 5.48 g for axial and resultant peaks. Based on our findings, the restoration algorithm could skew data and potentially lead to incorrect conclusions if used without caution.

Footstrike angle cut-off values to classify footstrike pattern in runners.

Footstrike angle (FSA) has been widely used to classify footstrike pattern (FSP). However, inconsistent FSA cut-off values were adopted in previous studies. This study aimed to validate the FSA cut-off values in runners. Stride index, the gold standard to determine FSP, and FSA were obtained when 15 experienced runners, 14 novice runners and 14 untrained individuals performed 3-min run on an instrumented treadmill at their preferred running speeds in habitual, rearfoot, midfoot and forefoot strike patterns. According to the receiver operating characteristic curve associated with the Youden index, the optimal FSA cut-off values were -0.8° (i.e., cut-off angle for forefoot strike) -7.4° (i.e., cut-off angle for rearfoot strike) for runners. We observed minor differences in the FSA cut-off values across runners with various running experience and a wider cut-off range for midfoot strikers when a modified strike index was utilized. This validation study established cut-off footstrike angles for runners' FSP classification.

Sensor-Based Gait Retraining Lowers Knee Adduction Moment and Improves Symptoms in Patients with Knee Osteoarthritis: A Randomized Controlled Trial.

The present study compared the effect between walking exercise and a newly developed sensor-based gait retraining on the peaks of knee adduction moment (KAM), knee adduction angular impulse (KAAI), knee flexion moment (KFM) and symptoms and functions in patients with early medial knee osteoarthritis (OA). Eligible participants (n = 71) with early medial knee OA (Kellgren-Lawrence grade I or II) were randomized to either walking exercise or gait retraining group. Knee loading-related parameters including KAM, KAAI and KFM were measured before and after 6-week gait retraining. We also examined clinical outcomes including visual analog pain scale (VASP) and Knee Injury and Osteoarthritis Outcome Score (KOOS) at each time point. After gait retraining, KAM1 and VASP were significantly reduced (both Ps < 0.001) and KOOS significantly improved (p = 0.004) in the gait retraining group, while these parameters remained similar in the walking exercise group (Ps ≥ 0.448). However, KAM2, KAAI and KFM did not change in both groups across time (Ps ≥ 0.120). A six-week sensor-based gait retraining, compared with walking exercise, was an effective intervention to lower medial knee loading, relieve knee pain and improve symptoms for patients with early medial knee OA.

Shoe-mounted accelerometers should be used with caution in gait retraining.

Real-time biofeedback gait retraining has been reported to be an effective intervention to lower the impact loading during gait. While many of the previous gait retraining studies have utilized a laboratory-based setup, some studies used accelerometers affixed at the distal tibia to allow training outside the laboratory environment. However, many commercial sensors for gait modification are shoe-mounted. Hence, this study sought to compare impact loading parameters measured by shoe-mounted and tibia sensors in participants before and after a course of walking or running retraining using signal source from the shoe-mounted sensors. We also compared the correlations between peak positive acceleration measured at shoe (PPAS ) and tibia (PPAT ) and vertical loading rates, as these loading rates have been related to injury. Twenty-four and 14 participants underwent a 2-week visual biofeedback walking and running retraining, respectively. Participants in the walking retraining group experienced lower PPAS following the intervention (P < 0.005). However, they demonstrated no change in PPAT (P = 0.409) nor vertical loading rates (P > 0.098) following the walking retraining. In contrast, participants in the running retraining group experienced a reduction in the PPAT (P = 0.001) and vertical loading rates (P < 0.013) after running retraining. PPAS values were four times that of PPAT for both walking and running suggesting an uncoupling of the shoe with tibia. As such, PPAS was not correlated with vertical loading rates for either walking or running, while significant correlations between PPAT and vertical loading rates were noted. The present study suggests potential limitations of the existing commercial shoe-mounted sensors.

The biomechanical difference between running with traditional and 3D printed orthoses.

Running-related injuries have been associated with excessive foot pronation and high vertical loading rates. Traditional plaster-molded (TPM) foot orthoses are commonly prescribed to minimize these atypical biomechanical patterns. Recently, 3D printed (3DP) orthoses have become popular, yet the functional difference between these two types of orthoses remains unknown. Therefore, this study compared running biomechanics and perceived comfort during treadmill running in three orthotic conditions: 3DP orthoses, TPM orthoses, and a no-orthoses control condition (CON). Thirteen female asymptomatic runners with excessive foot pronation were recruited. Rearfoot eversion angle and velocity (at initial contact and peak) during stance, vertical loading rates, and perceived comfort were compared. Results showed lower peak rearfoot eversion angles during running with TPM (p=0.001, d=0.38) or 3DP orthoses (p=0.002, d=0.24) than CON. No differences were observed in other biomechanical parameters among the three conditions (p>0.05). Running with TPM (p≤0.001, d=1.74-1.82) and 3DP orthoses (p<0.003, d=1.06-1.34) resulted in better perceived comfort in "medial-lateral control" and "heel cushioning" than CON. There were no statistical differences in all parameters between TPM and 3DP orthoses. The present findings indicate improved comfort during running with TPM or 3DP orthoses, which hinted 3DP orthoses could be a viable alternative to TPM orthoses for clinical practice.

Effects of footwear midsole thickness on running biomechanics.

Shoe manufacturers launch running shoes with increased (e.g., maximalists) or decreased (e.g., minimalists) midsole thickness and claim that they may prevent running injury. Previous studies tested footwear models with different midsole thicknesses on the market but the shoe construct was not strictly comparable. Therefore, in the present study, we examined the effect of midsole thickness, from 1-mm to 29-mm, in a standard test shoe prototype on the vertical loading rates, footstrike angle and temporal spatial parameters in distance runners. Fifteen male habitual rearfoot strikers were recruited from local running clubs. They were asked to run on an instrumented treadmill in shoes with different midsole thicknesses. We found significant interactions between midsole thickness with vertical loading rates (p < 0.001), footstrike angle (p = 0.013), contact time (p < 0.001), cadence (p = 0.003), and stride length (p = 0.004). Specifically, shoes with thinner midsole (1- and 5-mm) significantly increased the vertical loading rates and shortened the contact time, when compared with thicker midsole shoes (25- and 29-mm). However, we did not observe any substantial differences in the footstrike angle, cadence and stride length between other shod conditions. The present study provides biomechanical data regarding the relationship between full spectrum midsole thicknesses and running biomechanics in a group of rearfoot strikers.

Impact Loading During Distracted Running Before and After Auditory Gait Retraining.

Visual feedback gait retraining has been reported to successfully reduce impact loading in runners, even when the runners were distracted. However, auditory feedback is more feasible in real life application. Hence, this study compared the peak positive acceleration (PPA), vertical average (VALR) and instantaneous (VILR) loading rate during distracted running before and after a course of auditory feedback gait retraining in 16 runners. The runners were asked to land with softer footfalls with and without auditory feedback. Low or high sound pitch was generated according to the impact of particular footfall, when compared with the preset target. Runners then received a course of auditory gait retraining, and after the gait retraining, runners completed a reassessment. Runners before gait retraining exhibited lower PPA, VALR and VILR with augmented auditory feedback (p<0.049). We found a reduction in PPA, VALR and VILR after gait retraining, regardless of the presence of feedback (p<0.018). However, runners after gait retraining did not demonstrate further reduction in PPA and VALR with auditory feedback (p>0.104). A small effect of auditory feedback on VILR in runners after gait retraining was observed (p=0.032). Real time auditory feedback gait retraining is effective in impact loading reduction, even when the runners were distracted.

Immediate and short-term biomechanical adaptation of habitual barefoot runners who start shod running.

This study investigated the immediate and short-term effects of minimalist shoes (MS) and traditional running shoes (TRS) on vertical loading rates, foot strike pattern and lower limb kinematics in a group of habitual barefoot runners. Twelve habitual barefoot runners were randomly given a pair of MS or TRS and were asked to run with the prescribed shoes for 1 month. Outcome variables were obtained before, immediate after and 1 month after shoe prescription. Average and instantaneous vertical loading rates at the 1-month follow-up were significantly higher than that at the pre-shod session (P < 0.034, η2p > 0.474). Foot strike angle in the TRS group was significantly lower than that in the MS group (P = 0.045, η2p = 0.585). However, there was no significant time nor shoe effect on overstride, knee and ankle excursion (P > 0.061). Habitual barefoot runners appeared to land with a greater impact during shod running and they tended to have a more rearfoot strike pattern while wearing TRS. Lower limb kinematics were comparable before and after shoe prescription. Longer period of follow-up is suggested to further investigate the footwear effect on the running biomechanics in habitual barefoot runners.

Control of impact loading during distracted running before and after gait retraining in runners.

Gait retraining using visual biofeedback has been reported to reduce impact loading in runners. However, most of the previous studies did not adequately examine the level of motor learning after training, as the modified gait pattern was not tested in a dual-task condition. Hence, this study sought to compare the landing peak positive acceleration (PPA) and vertical loading rates during distracted running before and after gait retraining. Sixteen recreational runners underwent a two-week visual biofeedback gait retraining program for impact loading reduction, with feedback on the PPA measured at heel. In the evaluation of PPA and vertical loading rates before and after the retraining, the participants performed a cognitive and verbal counting task while running. Repeated measures ANOVA indicated a significant interaction between feedback and training on PPA (F = 4.642; P = 0.048) but not vertical loading rates (F > 1.953; P > 0.067). Pairwise comparisons indicated a significantly lower PPA and vertical loading rates after gait retraining (P < 0.007; Cohen's d > 0.68). Visual feedback after gait retraining reduced PPA and vertical loading rates during distracted running (P < 0.033; Cohen's d > 0.36). Gait retraining is effective in lowering impact loading even when the runners are distracted. In dual-task situation, visual biofeedback provided beneficial influence on kinetics control after gait retraining.

A new footwear technology to promote non-heelstrike landing and enhance running performance: Fact or fad?

This study sought to compare the kinetics and kinematics data in a group of habitual shod runners when running in traditional running shoes and newly designed minimalist shoes with lug platform. This novel footwear design claims to simulate barefoot running and reduce energy loss during impact. We compared footstrike angle (FSA), vertical average (VALR) and instantaneous (VILR) loading rates, energy loss and initial vertical stiffness between two shoe conditions. Runners demonstrated a decreased FSA while running in minimalist shoes with lug platform than traditional shoes (P = 0.003; Cohen's d = 0.918). However, we did not observe a landing pattern transition. VALR and VILR between two footwear conditions showed no significant difference (P = 0.191-0.258; Cohen's d = 0.304-0.460). Initial vertical stiffness (P = 0.032; Cohen's d = 0.671) and energy loss (P = 0.044; Cohen's d = 0.578) were greater when running in minimalist shoes with lug platform. The results show that minimalist shoes with lug platform reduce the FSA but may not lead to a landing pattern switch or lower vertical loading rates. Interestingly, the new shoe design leads to a greater energy loss than traditional running shoes, which could be explained by a higher initial vertical stiffness.

Chinese translation and validation of the Oxford Knee Scale for patients with knee osteoarthritis.

BACKGROUND: Oxford Knee Scale (OKS) is a commonly used instrument to assess the symptoms and functional status in people with knee osteoarthritis. However, a Chinese version of this scale is not yet available. OBJECTIVE: The objective of this study was to translate the OKS into Chinese and validate the Chinese version of OKS. METHODS: The Chinese OKS was translated from the original English version following the recommendations of the International Society for Pharmacoeconomics and Outcomes Research. One hundred Chinese reading patients with knee osteoarthritis were recruited from local hospitals and physiotherapy clinics. Psychometric properties were evaluated in terms of test-retest reliability and internal consistency. Convergent validity was examined by Spearman rank correlation coefficient tests by comparing its score with the validated Chinese version of the Western Ontario and McMaster Universities Osteoarthritis Index and Health Outcome Survey Short Form-36. RESULTS: Chinese OKS demonstrated excellent reliability (intraclass correlation coefficient = 0.88). Cronbach α of individual questions was > 0.7. Strong correlation was found between the Chinese OKS and the Western Ontario and McMaster Universities Osteoarthritis Index (ρ > 0.553, p < 0.001). Fairly strong negative correlation was also found between Chinese OKS and Health Outcome Survey Short Form-36 (ρ = -0.273 to -0.666, p < 0.05). CONCLUSION: The Chinese translated version of OKS is a reliable and valid instrument for clinical evaluation in Chinese reading patients with knee osteoarthritis.

Chinese adaptation and validation of the Knee Injury and Osteoarthritis Outcome Score (KOOS) in patients with knee osteoarthritis.

Knee Injury and Osteoarthritis Outcome Score (KOOS) is a commonly used instrument to assess the symptoms and functional status in people with knee injuries, including knee osteoarthritis. While China ranked the top country in the absolute number of people aged 65 or above, yet there is no validated Chinese version of this outcome measurement. This study translated and validated the KOOS into Chinese version. Chinese KOOS was translated from the original English version following standard forward and backward translation procedures recommended by the International Society for Pharmacoeconomics and Outcomes Research. Survey was then conducted in clinical settings by a questionnaire comprised Chinese KOOS, WOMAC Osteoarthritis Index, and Short Form 36 health survey (SF-36). One hundred Chinese reading patients with knee osteoarthritis were recruited from the orthopaedic out-patient department in hospitals. Internal consistency of the instrument was measured by Cronbach alpha. Construct validity was examined by Spearman's rank correlation coefficient (ρ) tests by comparing its score with the validated Chinese version of WOMAC Osteoarthritis Index and SF-36, while the test-retest reliability was evaluated by administering the questionnaires twice. Cronbach alpha values of individual questions and its overall value were above 0.70. Fairly strong association was found between the Chinese KOOS and the WOMAC Osteoarthritis Index (ρ = -0.37 to -0.86, p < 0.001). Diverse relationship was observed between Chinese KOOS and SF-36. Excellent test-retest reliability (ICC = 0.89-0.92) was demonstrated. The Chinese translated version of KOOS is a reliable and valid instrument for patients with knee osteoarthritis. The findings of current study might promote multinational investigations in this patient group.

A validation study of a smartphone application for functional mobility assessment of the elderly.

BACKGROUND: To minimize the reaction time and position judgment error using stopwatch-timed measures, we developed a smartphone application to measure performance in the five-time sit-to-stand (FTSTS) and timed up-and-go (TUG) tests. OBJECTIVE: This study aimed to validate this smartphone application by comparing its measurement with a laboratory-based reference condition. METHODS: Thirty-two healthy elderly people were asked to perform the FTSTS and TUG tests in a randomized sequence. During the tests, their performance was concurrently measured by the smartphone application and a force sensor installed in the backrest of a chair. The intraclass correlation coefficient [ICC(2,1)] and Bland-Altman analysis were used to calculate the measurement consistency and agreement, respectively, between these two methods. RESULTS: The smartphone application demonstrated excellent measurement consistency with the lab-based reference condition for the FTSTS test [ICC(2,1) = 0.988] and TUG test [ICC(2,1) = 0.946]. We observed a positive bias of 0.27 seconds (95% limits of agreement, -1.22 to 1.76 seconds) for the FTSTS test and 0.48 seconds (95% limits of agreement, -1.66 to 2.63 seconds) for the TUG test. CONCLUSION: We cross-validated the newly developed smartphone application with the laboratory-based reference condition during the examination of FTSTS and TUG test performance in healthy elderly.

Relationship between personal psychological capitals, stress level, and performance in marathon runners.

BACKGROUND: Marathon runners experience different levels of stress from their performance, which may vary across different people. OBJECTIVES: This study sought to examine if stress levels could be predicted by running performance and personal psychological capitals, including optimism and self-efficacy levels in marathon finishers. It also determined the contribution of each component in a stress prediction model. METHODS: An online questionnaire and comprised validated scales were used to measure runners' performance, perceived stress levels, and personal psychological capitals. RESULTS: A positive correlation between runner performance and perceived stress level (rs = 0.256, p = 0.019) was found, while the personal psychological capitals were negatively correlated to stress levels (rs = -0.580, p < 0.001) and (rs = -0.618, p < 0.001) respectively. Perceived stress levels were best predicted by personal psychological capitals (² = -0.322--0.393, p = 0.001), but not running performance. CONCLUSION: Our findings suggested that psychological factors affect stress levels the most, and marathon runners with a lower performance were more prone to stress than those who perform better.

Identification and Quantification of Precursory Changes of Rheumatoid Vasculitis in the Dorsalis Pedis Artery.

OBJECTIVE: Rheumatoid arthritis (RA) is a systemic connective tissue autoimmune disease that can infiltrate arterial walls. The delay in diagnosis and treatment of rheumatoid vasculitis (RV) in patients with RA may lead to irreversible damage to the arterial walls of small-to-medium vessels, which has serious and devastating consequences, most notably lung and cardiac damage. In this work an ultrasound image-based biomarker was developed to detect precursory changes in RV. METHODS: The ground truth was initiated from a medical diagnosis of RA, with arterial wall thickening of the proximal dorsalis pedis artery (DPA) indicating precursory changes of RV identified with ultrasound scanning. Ultrasound images of the DPA from 49 healthy subjects in the control group and 46 patients in the RA group were obtained. In total, 187 texture features were extracted from the images, followed by principal component analysis and linear discriminant analysis. RESULTS: The proposed biomarker detected a significant difference between the two groups (p = 5.74 × 10-18) with an area under the receiver operating characteristic curve of 0.85. Ten major textural features contributing most heavily to the biomarker were identified, with these textures being consistent with clinical observations of RV identified in previous studies. Interscan reproducibility was assessed by computing the biomarker twice based on repeated scans of each ankle. High interscan reproducibility was demonstrated by a strong and significant Pearson's coefficient (r = 0.85, p < 0.01) between the two repeated measurements of the proposed biomarker. CONCLUSION: The proposed biomarker can discriminate image textural differences seen in images acquired from RA patients, demonstrating precursory changes in RV compared with healthy controls. The major discriminative features identified in this study may facilitate the early identification and treatment of RV.

Chinese adaptation and validation of the patellofemoral pain severity scale.

OBJECTIVE: This study validated the Patellofemoral Pain Severity Scale translated into Chinese. DESIGN AND SETTING: The Chinese Patellofemoral Pain Severity Scale was translated from the original English version following standard forward and backward translation procedures recommended by the International Society for Pharmacoeconomics and Outcomes Research. The survey was then conducted in clinical settings by a questionnaire comprising the Chinese Patellofemoral Pain Severity Scale, Kujala Scale and Western Ontario and McMaster Universities (WOMAC) Osteoarthritis Index. SUBJECTS: Eighty-four Chinese reading patients with patellofemoral pain were recruited from physical therapy clinics. MAIN MEASURES: Internal consistency of the translated instrument was measured by Cronbach alpha. Convergent validity was examined by Spearman rank correlation coefficient (rho) tests by comparing its score with the validated Chinese version of the Kujala Scale and the WOMAC Osteoarthritis Index while the test-retest reliability was evaluated by administering the questionnaires twice. RESULTS: Cronbach alpha values of individual questions and their overall value were above 0.85. Strong association was found between the Chinese Patellofemoral Pain Severity Scale and the Kujala Scale (rho = -0.72, p < 0.001). Moderate correlation was also found between Chinese Patellofemoral Pain Severity Scale with the WOMAC Osteoarthritis Index (rho = 0.63, p < 0.001). Excellent test-retest reliability (Intraclass correlation coefficient = 0.98) was demonstrated. CONCLUSIONS: The Chinese translated version of the Patellofemoral Pain Severity Scale is a reliable and valid instrument for patients with patellofemoral pain.

Effect of surface inclination on vertical loading rate and footstrike pattern in trail and road runners.

Trail runners have been reported to be more injury prone than road runners. Limited past studies have examined the difference in the running biomechanics between the two groups of runners. More importantly, the effect of surface inclination has not been fully investigated. Hence, this study examined the effect of surface inclination on running biomechanics in trail and road runners. Twenty trails and 20 road runners were recruited in this study. Trail runners appeared to be more experienced and had longer training distance per week (p < 0.001) compared to road runners. All participants ran at a self-selected pace on an instrumented treadmill in three inclination conditions (i.e., level, +10% uphill and -10% downhill) in a random order. Vertical average loading rate (VALR), vertical instantaneous loading rate (VILR) and footstrike angle (FSA) were measured using established methods. Trail runners experienced greater VILR (p = 0.039, Cohen's d = 2.9) with a greater FSA (p = 0.002, Cohen's d = 1.1) during downhill running than road runners. No significant differences in VALR, VILR and FSA were found between the two groups during level and uphill running. Our findings provide potential biomechanical rationale to explain a higher injury incidence among trail runners.