Search

BACKGROUND: A potential relationship may exist between the vastus medialis (VM) and the contractile efficiency of the vastus intermedius (VI) due to their anatomical connection and common innervation by the same branches of the femoral nerve. However, this relationship has not been explored using physiological experiments. OBJECTIVE: This study aimed to use electromyography (EMG) to investigate the functional significance of the VI and VM muscles during isometric contraction. METHODS: Twenty-six healthy male volunteers underwent EMG recordings from the VI, VM, and vastus lateralis (VL) at 90∘ or 30∘ of knee flexion. The EMG pre-motor time (PMT) was measured during rapid knee extension in response to an auditory stimulus. Additionally, the M-wave latency was determined by femoral nerve stimulation and subtracted from the PMT to calculate the descending conduction time (DCT). RESULTS: DCT was shortest at VM, followed by VL and VI. The DCT difference of VI-VM was significantly greater than that of VI-VL during maximal effort at 90∘ of knee flexion. CONCLUSIONS: VM is neurally driven to act as a pre-activator that primes the VI muscle; this tendency is particularly pronounced when explosive high-moment knee extension is required. [ABSTRACT FROM AUTHOR]

BACKGROUND: The reduction of muscle mass and strength commonly observed after bariatric surgery might negatively affect the individual physical function. Muscle quality is also of functional relevance in different populations, but its significance in patients who underwent bariatric surgery has yet to be explored. OBJECTIVE: To examine the association between muscle strength and quality with physical function in women mid- to long-term after Roux-en-Y gastroplasty (RYGB). METHODS: In this cross-sectional study, 133 women (43.7 ± 9.9 years) who have undergone RYGB at least two years before the study were included. All participants underwent body composition evaluation using DEXA and knee extensors peak moment (PM) using an isokinetic dynamometer. Muscle quality (MQ) was obtained through the ratio between absolute PM and dominant leg fat-free mass. Physical function was measured through the 30-second sit-to-stand (30-STS), 6-minute walking (6-MWT), and timed up-and-go (TUG) tests. RESULTS: Differences between PM tertiles were observed for 30-STS and 6-MWT tests. However, statistical significance disappeared when adjusting for age. Regarding PM relative to body weight, all functional tests were significantly different between tertiles. Comparing functional performance according to MQ tertiles, differences were found for 30-STS and 6-MWT tests, but significance disappeared when adjusting for age. Absolute PM was correlated to the 30-STS performance and 6-MWT, while PM relative to body mass and MQ were correlated with all functional tests. CONCLUSIONS: Muscle strength and quality seem to be associated with physical function in women mid-to-long-term after RYGB, but strength relative to bodyweight outperformed absolute strength and MQ. [ABSTRACT FROM AUTHOR]

BACKGROUND: Lumbar stabilization exercises (LSE) provide dynamic trunk stability, promote muscle strength and endurance, and improve low back pain rehabilitation and performance. OBJECTIVE: To clarify the differences in trunk muscle activity during LSEs on stable and different unstable surfaces. METHODS: Fifteen healthy males performed three exercises (elbow-toe, hand-knee, and side bridge) on stable (floor) and unstable surfaces. Muscle activity of the bilateral rectus abdominis, internal oblique, external oblique, and erector spinae were recorded. Data were compared using the Friedman test. Pairwise comparisons were performed using Wilcoxon's signed rank test if significant differences were observed. RESULTS: In the elbow-toe exercise, muscle activity of the rectus abdominis and right internal oblique increased in the following order: floor, low-difficulty, and high-difficulty unstable surface. In the hand-knee exercise, muscle activity of the internal oblique on the lower-extremity elevated side, external oblique, and erector spinae on the upper-extremity elevated side were greater on unstable surface exercise performance. In the side bridge exercise, rectus abdominis muscle activity was highest on a high-difficulty unstable surface. CONCLUSION: Trunk muscle activity increased during exercise on unstable surfaces. Since the effects of unstable surfaces vary depending on muscle and exercise types, exercise difficulty and surface stability must be considered accordingly. [ABSTRACT FROM AUTHOR]

BACKGROUND: Haemophilic arthropathy is likely to influence posture and muscle stiffness in adolescent male haemophilia patients (HP). OBJECTIVE: This study aimed to investigate the possible change in upright standing posture and stiffness of the superficial postural muscles in HP. METHODS: Twenty-two HP aged between 12 and 19 years and twenty-two healthy peers were included in the study. The photogrammetry was used to assess the upright standing posture from sagittal and frontal planes. Also, stiffness of the superficial postural muscles was evaluated using the myotonometry. RESULTS: A significant difference was found in the craniovertebral, lumbar lordosis, knee flexion-valgus, and ankle plantar flexion angles between the groups (p < 0.05). Craniovertebral, knee flexion, and knee valgus angles were lower; whereas lumbar lordosis and ankle plantar flexion angles were higher in HP compared to the healthy peers. Stiffness of the rectus femoris muscle was lower in HP (p < 0.001). CONCLUSION: This study revealed that the ankle, knee, lumbar, and craniovertebral segments' posture angles were changed and the stiffness of the rectus femoris muscle decreased in HP. Postural alterations and reduced rectus femoris stiffness should be considered in management of the musculoskeletal complications of haemophilia. [ABSTRACT FROM AUTHOR]

PURPOSE: This study examined the effects of a dynamic neoprene orthosis on kinematic variables of gait in children with spastic bilateral cerebral palsy (CP). METHODS: Five children (whose median age was 9.6 years and who ranged in age from six to 12) with spastic bilateral CP and flexed knee at levels I-III of the Gross Motor Function Classification System were examined using kinematic gait analysis in three different conditions: 1) with dynamic neoprene orthosis; 2) without dynamic neoprene orthosis (immediate effect); and 3) without orthosis after six weeks of intervention. RESULTS: The comparison between condition one (with dynamic neoprene orthosis) and condition two (without dynamic neoprene orthosis) demonstrated the existence of improvements in minimum hip and knee flexion variables. Moreover, the results indicated that the improvements remained constant in several key gait variables after six weeks. CONCLUSION: The results varied from subject to subject, and there were signs of improvement in some of the subjects. Therefore, it was not possible to draw conclusions at a group level. Nonetheless, a number of individuals may benefit from this type of orthosis. [ABSTRACT FROM AUTHOR]

BACKGROUND: Joint position reproduction measures the angle acuity of reference angle reproduction using an indicator angle. However, reference angles are often not available. OBJECTIVE: This study aimed to examine joint position sense at three different targeted joint angles, which were estimated from the maximum range of motion (maxROM) without a reference angle at each targeted joint angle. METHODS: The maxROM was measured in straight leg raise (SLR) and active knee extension (AKE) positions. In both positions, a targeted joint angle at 75% of the maxROM was assessed first, followed by that at 50% and 25% of the maxROM. A one-sample t-test was used to analyze differences between the targeted and reproduced angles in both positions. RESULTS: All reproduced angles significantly differed from the targeted angle in both SLR and AKE positions except for the reproduced angle measured at 75% maxROM. Overall, position errors in the AKE position were higher than those in the SLR position. CONCLUSIONS: Estimating the angle based on the maxROM without a matched reference angle may lead to significant discrepancies in comparison with the targeted joint angle. In clinical settings, if accurate reproduction of motions is required to improve proprioception, providing a reference angle might be helpful. [ABSTRACT FROM AUTHOR]

BACKGROUND: To measure hamstring flexibility, the active knee extension (AKE) test is preferred over the straight leg raise (SLR) test as it can be used to measure hamstring flexibility more selectively. However, hamstring stretching is primarily conducted in the SLR position (maximal hip flexion in the supine position) as it allows for maximal hip flexion in the supine position. OBJECTIVE: This study evaluates the effects of proprioceptive neuromuscular facilitation (PNF) stretching in the AKE position (maximal knee extension with 90∘ flexion of the hip in the supine position) on hip, knee, and ankle flexibility. METHODS: SLR, AKE, and active dorsiflexion (ADF) tests were used to determine the range of motion (ROM) before (pre-ROM) and after (post-ROM) stretching. PNF stretching consisted of maximal isometric knee flexion at the end range with external resistance to prevent knee flexion. One set of PNF stretches (five trials of six seconds each) was conducted. RESULTS: The post-ROMs of hip, knee, and ankle measured via the SLR, AKE, and ADF tests, respectively, were significantly higher than the pre-ROMs. CONCLUSIONS: The improvement in knee flexibility was greater than the improvement in hip and ankle flexibility. The AKE position is recommended in clinical settings during PNF stretching for individuals with hamstring tightness. Furthermore, PNF stretching in the AKE position increases the ADF ROM. [ABSTRACT FROM AUTHOR]

BACKGROUND: This study on gait biomechanics is based on a functional test (FT) performed at free and fast walking speeds. OBJECTIVE: We investigated the pattern of changes in gait biomechanical parameters and the knee function in patients after anterior cruciate ligament (ACL) injury or its reconstruction. METHODS: The study included 51 patients (33 males, 18 females) with a confirmed recent or old history of ACL tear, before or after reconstruction (26 patients). Mocap data was obtained using an inertial system. All patients were divided into three groups: 41 patients with physiological response (compensation), 6 patients with signs of decompensation, and 4 non-assessable patients. RESULTS: Increase in gait speed was associated with decrease in the walking cycle duration, stance and double support phases. In the compensation group, the physiological response of the knee was manifested in increased amplitudes. In the decompensation group, the amplitudes remained unchanged or decreased. In the compensation group, there were increases in the symmetrical muscle activity. The decompensation group was characterized by electromyography asymmetry. CONCLUSION: The observed universal physiological mechanism limiting the load on the damaged joint can be used for accurate assessment of the knee functional state in various periods of rehabilitation. [ABSTRACT FROM AUTHOR]

BACKGROUND: Postactivation potentiation (PAP) enhances contractility of skeletal muscle whereas fatigue deteriorates it. Available evidence suggests that the two phenomena may express differently in endurance and power athletes. OBJECTIVE: To compare the patterns of change in knee muscle contractility induced by PAP and fatigue between endurance and power athletes. METHODS: Eleven endurance and ten power athletes (age: 18–33 years) performed isokinetic fatigue and isometric PAP protocols with knee extensors and flexors on computerised dynamometer. Tensiomyography (TMG) of the vastus medialis and semitendinosus muscle medialis was performed before the protocols and during a 10-min recovery. RESULTS: The changes in TMG profile were most pronounced in the vastus medialis of power athletes following the PAP protocol and least pronounced in the semitendinosus of the endurance athletes following the fatigue protocol. The differences between athlete types were most significant for the time-domain TMG parameters of vastus medialis. A significant correlation (r = 0.51–0.73) between the fatigue indices and changes in TMG parameters was observed for the vastus medialis muscle only. CONCLUSIONS: The results show that the TMG patterns of PAP and fatigue in the vastus muscle differ between endurance and power athletes. In this muscle, the changes in TMG parameters are also strongly associated with the degree of fatigue. [ABSTRACT FROM AUTHOR]

BACKGROUND: Kinesiotape application is one of the non-pharmacological methods frequently used in patients with knee OA. Guidelines do not have a consensus on its use in knee osteoarthritis (OA). OBJECTIVE: In this study, we aimed to investigate the acute effect of kinesiotape application on pain, balance, and gait performance in patients with knee OA. METHODS: We included 164 patients with grade 1–3 knee OA according to the Kellgren-Lawrence staging system in the study. Patients were evaluated with visual analog scale (VAS), 10-meter walking test (10MeWT), timed-up and go test (TUG-T), single leg stance test (SLST), and functional reach test (FRT) before and after taping. RESULTS: There was a significant improvement in the post-taping scores of all evaluation parameters in the kinesiotaping group compared with pre-taping scores. Statistically significant improvement was found in all scores of evaluated parameters except FRT scores in the placebo taping group. We found a significant superiority in the mean recovery scores of the kinesiotaping group compared to the placebo-taping group in all parameters except for 10MeWT. CONCLUSIONS: We found significant improvements in both groups. The mean improvement levels in pain and balance scores were better in the KT group than in the PT group. [ABSTRACT FROM AUTHOR]

BACKGROUND: Even though literature indicates presence of weak hip abductors and lateral rotators' in Patellofemoral Pain (PFP), studies evaluating the effect of hip abductors and lateral rotators strengthening to improve knee function and quality of life in PFP are limited. OBJECTIVE: This study systematically reviews and meta-analyzes the best evidence on the therapeutic value of strengthening hip abductors and lateral rotators muscles for treating PFP with a presumptive hypothesis that strengthening hip muscles stabilizes the patellofemoral joint, relieves pain, and enhances knee functions. METHOD: Medline, EMBASE, CINAHL, PEDro and PubMed Central databases were searched between January 1994 and September 2019 using the PICOS tool. The methodological quality of the selected studies were appraised individually using the 20-item McMaster Critical Review Form for Quantitative Studies. Supplemental quality appraisal of randomized controlled clinical trials performed using the Cochrane Collaboration's 'Risk of bias' quality criteria. Data on patient population demographics, interventions, duration of intervention, and outcome measures were extracted and summarized in evidence tables and descriptive analysis. Meta-analyses under both fixed and random-effects models determined pooled effects size from appropriate RCTs. RESULTS: All fourteen studies demonstrated that hip muscle strengthening improved pain and knee function. All RCTs, except one, demonstrated that hip muscle strengthening is superior to quadriceps strengthening. Of the five RCTs assessing the additional effect of hip-quad versus quadriceps strengthening, four suggested that hip-quad strengthening is superior to standard quadriceps strengthening alone to improve PFP and knee function. CONCLUSION: In adult patients with PFP, strengthening hip abductors and lateral rotators' have beneficial therapeutic effects than the conventional quadriceps exercises in improving knee pain and function both in the short- and long term. However, the present review data can be used to develop a standardized hip-quad protocol in the future. [ABSTRACT FROM AUTHOR]

BACKGROUND: There is no consensus about which training methods will give better early outcomes after total hip arthroplasty (THA). OBJECTIVE: To investigate the short-term effects of cross trainer exercise on physical function and walking ability following THA. METHODS: Fifty patients who underwent THA were randomly allocated into two groups. The intervention program was started 3 days after surgery. The main physical function results were pain, hip range of motion, knee extensor strength, single-leg stance time, and walking performance test. In addition, the number of days of requiring to walk and the length of hospital stay were recorded. RESULTS: In the comparison between groups at discharge, the patients in the cross trainer group had significantly less hip pain while walking, improvement in knee extensor strength, increased single-leg stance time, as well as increased walking speed and stride length at discharge. The number of days required to walk and length of stay were also significantly lower in the intervention group. CONCLUSIONS: Conclusions: Cross trainer exercise commencing 3 days postoperatively improves physical function and walking ability after THA. [ABSTRACT FROM AUTHOR]

BACKGROUND: Most previous studies have focused on increasing hamstring flexibility when knee extension range of motion (KE ROM) is restricted. However, it was demonstrated that the tensile force generated in the upper body could be transmitted to the contralateral lower extremity. OBJECTIVE: This study examined the effect of novel diagonal stretching combining trunk rotation and trunk flexion on the contralateral KE ROM. METHODS: Two different positions (sitting with a neutral pelvis position and sitting with trunk rotation) were randomly selected and the contralateral and ipsilateral KE ROM was measured in each position. As for the stretching intervention, trunk rotation and slight trunk flexion were applied in sitting with a neutral pelvic position. RESULTS: On the contralateral side, KE ROM was significantly different in all pairwise comparisons (p < 0.001). On the ipsilateral side, a significant difference in KE ROM was only observed between measurements taken after stretching compared to measurements taken during trunk rotation (p = 0.005). CONCLUSIONS: The tensile force in the upper body significantly affects tissue extensibility in the lower extremity in the contralateral side, leading to the restriction of active maximum knee extension. Diagonal stretching techniques may successfully enhance mobility in the contralateral leg. [ABSTRACT FROM AUTHOR]

PURPOSE: This initiative aimed to assess adherence to Scottish Rite for Children's serial casting protocol for children with idiopathic toe walking (ITW), factors related to adherence, and outcomes after education regarding the protocol. METHODS: 60 patients aged 7.1±2.7 years who completed serial casting were examined at baseline phase (n = 30) and post-education phase (n = 30). Protocols include weekly serial casting for 4 to 6 weeks to achieve 10° of ankle dorsiflexion (ADF) passive range of motion (PROM) with knees extended (KE), assessing the foot posture index (FPI-6) and single leg stance (SLS). Baseline phase evaluated adherence to protocols. Education phase evaluated factors related to adherence and education regarding serial casting findings. Post-education phase evaluated the impact of the education phase. RESULTS: Serial casting averaged 4.8±1.5 weeks (n = 60). ADF PROM was measured with 100% adherence. ADF PROM KE averaged –10.7° pre-cast and significantly improved to +6.5° post-cast (n = 60), and it significantly improved post-cast post-education (p = 0.04). FPI-6 and SLS adherence significantly improved post-cast post-education. FPI-6 total score averaged +5.3 at baseline and +5.8 post-cast (n = 35). CONCLUSION: Education of staff in serial casting protocols improved adherence and patient outcomes. Patients with ITW and ADF PROM KE –10° benefit from serial casting to improve PROM and to allow for orthotic use post-casting. [ABSTRACT FROM AUTHOR]

BACKGROUND: Hand-held dynamometry (HHD) is used to assess muscle strength in various patient populations, but many variations in protocols exist. OBJECTIVE: First, to systematically develop a protocol of HHD for all lower limb muscle groups and evaluate intra-rater reliability; second, to validate HHD with fixed dynamometry for the knee flexor and extensor muscles. METHODS: Thirty healthy young adults (women: men – 15:15) participated in two testing sessions. HHD of 12 lower limb muscle groups was performed in both sessions, while fixed dynamometry of knee muscle groups was performed only in the second session. RESULTS: The intra-rater reliability of HHD was good for five muscle groups and excellent for seven muscle groups (ICC3, k = 0.80–0.96). The criterion validity of HHD ranged from very good to excellent for the knee flexors (r = 0.77–0.89) and from good to very good for the knee extensors (r = 0.65–0.78). However, peak moment values for the knee extensor muscles were underestimated by 32% (p < 0.001). CONCLUSIONS: The proposed HHD protocol provides reliable and valid measurements of lower limb muscle isometric strength in healthy adults, which may also be used to test patients with mild muscle strength deficits. However, possible underestimation of absolute strength must be considered when interpreting the results of knee extensors or other large muscles. [ABSTRACT FROM AUTHOR]

BACKGROUND: Law enforcement officers experience high stress levels and perform various physical tasks. Thus, law enforcement academies emphasize physical fitness training and assessment. OBJECTIVE: To examine fitness test-performances and determine which entry-level fitness components best predict likelihood of successful law enforcement academy graduation. METHODS: Recruits (151 males, 42 females) completed initial academy fitness testing: one-repetition maximum bench press, push-ups, sit-ups, pull-ups, sit-and-reach, 1.5-mile run, and work performance test. Chi-square and t-tests were used to examine gender differences. Correlation coefficients assessed relationships, while logistical regression determined the best fitness components for predicting graduation (p < 0.05). RESULTS: Males had greater fitness performances except pull-ups, sit-ups and sit and reach (p < 0.05). Distributions of below average fitness performances were similar between genders with majority of recruits performing below average on all tests. Gender, age, push-ups, and pull-ups explained 18% of the variance in graduation rates (p < 0.05). Males were 4.68 (p < 0.05) times more likely to graduate, but other predictors were not significant. CONCLUSIONS: No single fitness test predicted the likelihood of graduation and majority of performances were below average, suggesting the importance for proficiency across multiple fitness components. Considering lower fitness performances and graduation rates, females may further benefit from training programs prior to academy entrance. [ABSTRACT FROM AUTHOR]

BACKGROUND: It is important for clinicians and researchers to perform dynamic postural control evaluation for predicting musculoskeletal conditions, injury prevention, and rehabilitation. OBJECTIVE: The purpose of this study was to investigate the relationship (1) between the eccentric strength of the knee extensors and star excursion balance test (SEBT), and (2) between the knee proprioception and SEBT. METHODS: Forty healthy young adults participated in this study. The eccentric peak torque (EPT) of the knee extensors, joint position sense, and force sense were measured. The participants also performed SEBT. Pearson's product-moment correlation and multiple linear regression analysis were used to determine the relationship between the variables and SEBT. RESULTS: The posteromedial direction of the SEBT was positively and strongly correlated with EPT (r = 0.74, P < 0.01). The anterior and posterolateral directions were positively and moderately correlated with EPT (r = 0.46, P < 0.01, and r = 0.69, P < 0.01, respectively.). However, knee proprioception was not correlated with all the directions of SEBT (P > 0.05). According to the results of multiple linear regression analysis, EPT of the knee extensors significantly predicted SEBT reach distances. CONCLUSION: The eccentric strength of the knee extensors seems to be an essential factor in dynamic postural control. However, the knee proprioception did not show a significant correlation with SEBT. [ABSTRACT FROM AUTHOR]

BACKGROUND: Knee strength weakness is a major problem frequently observed in patients during postoperative rehabilitation following anterior cruciate ligament reconstruction (ACLR). OBJECTIVE: To investigate whether knee strength normalized to muscle volume could better detect side-to-side differences than that normalized to body weight following ACLR. METHOD: This study included 17 patients who had undergone primary ACLR (11.6 ± 2.3 months). Body weight and total muscle volume were measured using a bioelectrical impedance analysis composition scale. Isokinetic knee extension and flexion moment were measured at 60 ∘ /s and 180 ∘ /s, respectively. Bivariate correlation analysis was used to examine correlations between body composition and knee strength. Differences in knee strength between the operated and unoperated legs were analyzed using a paired t -test, which calculated the effect size. RESULTS: There was a significant correlation between knee strength and body weight (r = 0.53–0.67); however, a stronger correlation was observed between knee strength and total muscle volume (ρ = 0.80–0.87). The effect size was larger for knee strength expressed as % total muscle volume than for knee strength expressed as % body weight. CONCLUSION: Strength expressed as % total muscle volume may be more accurate than that expressed as % body weight for detecting side-to-side differences in knee strength following ACLR. [ABSTRACT FROM AUTHOR]

BACKGROUND: In medial knee osteoarthritis (knee OA), compensatory overstrain of the rectus femoris (RF) muscle leads to its hypertrophy. We hypothesize that besides hypertrophy of the RF, a prominent flattening of the central aponeurosis (CA) curvature is also indicative of RF. This study aims to evaluate the structural changes in the CA and clarify the conditions associated with RF overstrain in knee OA. OBJECTIVE: Twenty-three legs of 20 elderly without knee OA (elderly group) and 26 legs of 20 individuals with K-L grade II knee OA (knee OA group) with typical "comma"-shaped CA participated in this study. METHODS: The knee extension torque (Nm/kg) in the sitting position, the thickness of the RF and vastus intermedius (VI) muscles (VI), and change in CA curvature (%Curvature) were measured at the mid-thigh by ultrasonography. RESULTS: The knee extension torque was not significantly different between the two groups. Compared to the elderly group, the knee OA group had significantly thicker RF at rest, while the VI thickness during contraction was significantly smaller. The %Curvature was significantly higher in the knee OA group than in the elderly group. CONCLUSIONS: In the knee OA group, the RF was hypertrophic with a more pronounced CA flattening during muscle contraction, although the other quadriceps muscles were atrophic, suggesting an overstrained RF. Assessing thickness and CA curvature of the RF is, therefore, useful and simple for evaluating overstrain caused by RF compensation. [ABSTRACT FROM AUTHOR]

BACKGROUND: Force perception as a contributor to the neuromuscular control of the knee joint may be altered after anterior cruciate ligament (ACL) injury. OBJECTIVE: This study aimed to compare the force perception accuracy in the knee joints of patients with ACL injury and healthy subjects. METHODS: Twenty-six patients with ACL injury and 26 healthy subjects participated in this case-control study. Participants were asked to produce 50% of the maximum voluntary isometric contraction of the knee muscles as a target force and reproduce it in their limbs in flexion and extension directions. RESULTS: There were significant interactions between group and condition as well as group, condition, and limb in the force perception error respectively (P < 0.05). The highest amount of error was seen in the contralateral limb of the ACL injury group when the reference force was produced in the injured limb (P < 0.05). CONCLUSION: The findings revealed that the force perception accuracy in the knee flexor/extensor muscles of individuals with ACL injury is impaired. Moreover, error is most evident when the patient produces force in the injured limb and replicates it in the uninjured limb in both flexion and extension directions. Therefore, the rehabilitation programs should encompass neuromuscular training in both quadriceps and hamstrings after ACL injury. [ABSTRACT FROM AUTHOR]

BACKGROUND: Lower limb muscular asymmetry is not well studied and may have a negative impact on performance. OBJECTIVE: To estimate how muscular strength and strength asymmetry affect jumping performance in soccer players. METHODS: Twenty-eight male professional soccer players took part in the study. The countermovement jump (CMJ) without arm swing was used to determine jumping height. Muscle strength was measured concentrically at 60 and 300 ∘ /s. RESULTS: The peak moment of the knee extensors was positively and significantly correlated with the CMJ; r = 0.608 at 300 ∘ /s and r = 0.489 at 60 ∘ /s. The asymmetry of the knee flexors between the stronger and weaker leg was negatively and moderately correlated with the CMJ at 300 ∘ /s (r = - 0.396). The regression model ( R 2 = 0.474) showed that an increase of 0.18-Nm/kg in the relative strength of the knee extensors at 300 ∘ /s (by one SD) was related to an increase of 3-cm in the CMJ. Reducing the asymmetry of the knee flexors by 6.8 percentage points (by one SD) was related to a rise of 1.7-cm in the CMJ. CONCLUSIONS: Greater strength in the knee extensors, preferably tested at higher velocity, and reduced asymmetry in the strength of the lower hamstring muscles have a statistically significant effect on the CMJ. [ABSTRACT FROM AUTHOR]

BACKGROUND: Hamstring flexibility plays a significant role in physiotherapy. Various stretching studies have been conducted to increase hamstring flexibility, but the effects of the Fascial Distortion Model (FDM) on hamstring flexibility have not yet been investigated. Moreover, no studies have compared the effects of FDM and static stretching. OBJECTIVES: To investigate the effects of the FDM on hamstring flexibility compared with static stretching. METHODS: Thirthy healthy adults were divided into two groups: static stretching and FDM groups. Static stretching was performed to hamstring in the supine position. The FDM was performed using trigger band techniques that followed the hamstring in a longitudinal direction. Hamstring flexibility was measured using the active knee extension angle (KEA), passive straight leg raising (SLR), sit-and-reach (SR), and finger-floor distance (FFD) tests. A paired t -test and an independent t -test were performed to compare the hamstring flexibility measurements. RESULTS: Both groups showed significant differences (p < 0.05) in KEA, SLR, SR, and FFD before and after. However, no significant difference (p > 0.05) was found between the two groups. CONCLUSIONS: There was no difference in the effects of FDM and static stretching on hamstring flexibility. [ABSTRACT FROM AUTHOR]

BACKGROUND: Isokinetic evaluation is considered the gold standard in muscle strength measurement due to its sensitivity, intra-dynamometer reproducibility and usefulness in the injury prevention screening and follow up of subjects with musculoskeletal pathologies, neurological disease or after surgical operation. However, can one switch among different isokinetic dynamometers for the purpose of knee muscles evaluation? OBJECTIVES: To comprehensively evaluate the compatibility of the isokinetic short concentric and eccentric strength evaluation protocol and of the fatigability resistance evaluation between three different isokinetic devices. METHODS: Eighteen recreationally active men underwent three isokinetic knee testing sessions on three different isokinetic devices with 7–10 days of rest between each session. Relative (Pearson's r product-moment correlation coefficient – PCC) and absolute (standard error of measurement – SEM, Cohen effect sizes (d) and probabilistic inferences – MBI) parameters of reproducibility were determined to assess the inter-dynamometer agreement. RESULTS: For the short concentric and eccentric strength evaluation protocol, the extensors in concentric mode and the flexors in eccentric mode can be compared (eventually with transposition formulas provided) between Biodex, Con-Trex and Cybex (almost all PCC ⩾ 0.80). The DCR could be compared between Con-Trex and Cybex and between Biodex and Cybex pairs (eventually with transposition formula provided). For the fatigability resistance evaluation protocol, the total sum can be compared for extensors (eventually with transposition formulas provided) for PM for all dynamometer pairs considered and, in the case of MW, only for Biodex and Con-Trex (PCC ⩾ 0.80). CONCLUSIONS: Only some of the parameters derived either from the short concentric and eccentric strength evaluation protocol or the fatigability resistance evaluation protocol may be interchangeable providing transposition formulas are applied. Otherwise, isokinetic findings are largely system-dependent save some specific instances. [ABSTRACT FROM AUTHOR]

BACKGROUND: Nearly half of persons with Parkinson disease (PD) report fatigue as a factor in their fall history. However, it is unknown whether these self-reported falls are caused by a sensation of fatigue or performance fatigue. OBJECTIVE: We sought to investigate the influences of performance fatigue and age on postural control in persons with PD. METHODS: Individuals with PD (n = 14) underwent postural control assessments before (T0) and immediately after (T1) fatiguing exercise. Biomechanical data were gathered on participants completing a treadmill-induced, posterior-directed fall. Performance fatigue was produced using lower extremity resistance exercise on an isokinetic ergometer. Repeated measures ANCOVAs were used with age as a covariate to determine the effects of performance fatigue on biomechanical variables. RESULTS: After adjustment for age, there was a statistically significant difference in peak center of pressure (COP) latency during the support phase of recovery. Pairwise comparisons demonstrated a decrease in peak ankle displacement from T0 to T1. Age was also found to be significantly related to reaction time and peak knee displacement while participants were fatigued. CONCLUSIONS: The decreased peak COP latency, along with decreased ankle angular displacement, suggest that persons with PD adopt a stiffening strategy in response to backward directed falls. Postural stiffening is not uncommon in persons with PD and could be a risk factor for falls. Older individuals with PD demonstrate slower mobility scores and decreased reaction times in the setting of fatigue, suggesting a combined effect of the aging and fatigue processes. [ABSTRACT FROM AUTHOR]

BACKGROUND: Although the common practice of verbal encouragement is scientifically supported, its effect on the maintenance of force output in fatiguing exertions is unknown. OBJECTIVE: To examine the effects of verbal encouragement on exercise-induced quadriceps and knee joint function during three sets of knee extension exercise. METHODS: Sixty-five healthy males (23.3 years, 175.8 cm, 75.3 kg) underwent testing using the administration of verbal encouragement (n = 32) or not (n = 33) during assessment of quadriceps and knee joint function. Assessments were performed at baseline and times 1, 2, and 3. The knee concentric isokinetic extension at 60 ∘ /s, was performed between the time points. For quadriceps function, maximal isometric strength and activation (central activation ratio) were recorded. Absolute error values on knee flexion replications at 15 ∘ or 45 ∘ were recorded for knee joint function. RESULTS: There was no verbal encouragement effect over three sets of exercise in quadriceps strength (condition × time: F 3 , 189 = 1.71, p = 0.17) and knee flexion replication (condition × time for 15 ∘ : F 3 , 189 = 0.11, p = 0.96; 45 ∘ : F 3 , 189 = 0.63, p = 0.6). However, subjects who had received verbal encouragement maintained quadriceps activation (condition × time: F 3 , 189 = 5.49, p = 0.001). Specifically, quadriceps activation in the verbal condition was 3.0% higher at time 2 (p = 0.01) and 4.7% higher at time 3 (p = 0.0003) versus in the non-verbal condition. CONCLUSIONS: Verbal encouragement appears to be effective in maintaining central activation, but is insufficient for promoting strength. This supports the idea that peripheral contributing factors play a larger role in force production when performing multiple sets of exercises. [ABSTRACT FROM AUTHOR]

BACKGROUND: Comparison of knee loads on a Smith machine, which is utilised for maintenance of health and rehabilitation, has not been attempted. OBJECTIVE: This study compared lower limb muscle and knee joint forces during front and back squats performed on a Smith Machine. METHODS: Eleven participants performed front and back squats with loads at 40%, 60% and 80% of their back squat 1-RMs. Ground reaction forces and three-dimensional full body motion were collected and used for modelling lower limb muscle and knee joint forces. RESULTS: Larger loads increased tibiofemoral compressive force during back squat at 80% compared to 40% (p < 0.01; d = 1.58) and to 60% (p < 0.01; d = 1.37). Patellofemoral compressive (p = 0.96) and tibiofemoral shear forces (p = 0.55) were not influenced by external load or type of squat. Gluteus medius and minimus produced more force at 80% compared to 60% (p = 0.01; d = 1.10) and to 40% (p < 0.01; d = 1.87) without differences for other muscles (p = 0.09–0.91). CONCLUSIONS: Greater external load was associated with increase in gluteus medius and minimus force and with increased tibiofemoral compressive force without effects on tibiofemoral shear force, patellofemoral compressive force or other lower limb muscle forces. [ABSTRACT FROM AUTHOR]

INTRODUCTION: Cycling has been the subject of numerous studies. Among these, measuring muscular performance during cycling has attracted much interest. OBJECTIVE: To investigate the relationship between Wattbike ® and isokinetic findings in a group of cyclists. METHODS: Thirty-seven male cyclists performed a 30-s anaerobic power test on a Wattbike ® and then were tested concentrically for knee extensor and flexor strength using isokinetic dynamometry. RESULTS: There was a positive fair-to-moderate correlation between the peak moment, peak power, and total work derived from the Wattbike ® and the respective parameters evaluated isokinetically. CONCLUSION: While the findings exclude interchangeability of the two methods, the fact that total work is the most closely associated parameter among the measurements highlights its importance as an outcome measure in muscle performance in cyclists. [ABSTRACT FROM AUTHOR]

BACKGROUND: Sit-to-stand test is very often used as measure of lower limb strength in elderly adults. However, the recent findings indicate that performance in this test is also influenced by other factors. OBJECTIVE: To investigate the association between anthropometric, lower limb strength, and balance variables with the 5-repetition sit-to-stand test (5RSTST) in elderly women. METHODS: Forty physically active elderly women ⩾ 60 years underwent the 5RSTST and anthropometric, balance, and lower limb strength assessment. Anthropometric measurements included height and weight. Balance was quantified in the bipedal upright stance on the basis of the centre of pressure sway in the anteroposterior (CoP AP) and mediolateral (CoP ML) direction. Bilateral concentric strength of the ankle plantarflexors and dorsiflexors, knee flexors and extensors, and hip extensors was measured. RESULTS: The time to complete the 5RSTST was significantly but mildly associated with height (r = 0.356, p = 0.024), ankle dorsiflexor strength (r = - 0.413, p = 0.017), knee flexor strength (r = - 0377, p = 0.030), knee extensor strength (r = - 0.411, p = 0.017), hip flexor strength (r = - 0.359, p = 0.040) on dominant limb, and balance in both directions (AP, r = 0.651, p < 0.001; ML, r = 0.647, p < 0.001). Balance control in AP direction and knee extensor strength on dominant limb were the only factors that contributed independently to 5RSTST, accounting for 55% of the variance. Balance control in AP direction alone explained 41% of the variance in 5RSTST. CONCLUSIONS: Balance control in AP seems to be the most important factor explaining the 5RSTST performance. [ABSTRACT FROM AUTHOR]

BACKGROUND: An increase in the compensatory action of the quadratus lumborum (QL) during side-lying hip abduction (SHA) can lead to lateral movement impairment of the pelvis. OBJECTIVE: To compare the effects of knee flexion (KF) and knee extension (KE) during SHA at abduction angles of 25 ∘ , 35 ∘ , and 45 ∘ on the activity and onset time of the gluteus medius (GM) and QL. METHODS: Thirty healthy men were recruited and randomly divided into two groups: those with SHA with KF and those with SHA with KE. The subjects performed SHA at three angles of abduction in a random order. Surface electromyography was used to record the muscle activities of the GM and QL. RESULTS: The QL activity decreased significantly more in the KE group than in the KF group at each of the three angles of abduction during SHA. The GM/QL activity ratio increased significantly in the KE compared to the KF group. In addition, in the KE group, the onset of the GM activity was significantly earlier than that of the QL activity. On the other hand, in the KF group, the onset of the GM activity occurred later than that of the QL activity. CONCLUSIONS: These findings indicate that KE is more effective than KF in selectively activating the GM during SHA by reducing the QL activity and firing the GM earlier than the QL. [ABSTRACT FROM AUTHOR]

BACKGROUND: Previous studies have indicated that the kinematics of the knee joint affect the trunk and pelvis during gait. However, the factors that influence trunk movement in knee osteoarthritis patients during gait after surgery remain unclear. OBJECTIVE: To examine the effect of total knee arthroplasty (TKA) on trunk movement during gait by comparing knee osteoarthritis patients with healthy controls. METHODS: Fourteen medial knee osteoarthritis patients who underwent initial unilateral TKA and 11 controls participated in this study. Knee and hip joint flexion and trunk and pelvic tilts during gait were acquired using a three-dimensional motion analysis system. Knee joint range of motion, pain, and kinematic data were collected preoperatively and 1 year postoperatively for knee osteoarthritis patients. RESULTS: Knee extension limitation and pain significantly improved postoperatively compared with preoperative stages. Preoperatively, the peak anterior trunk tilt during the stance phase was significantly larger in osteoarthritis patients than in controls. The peak anterior trunk tilt during the stance phase was significantly smaller postoperatively than at preoperative stages. CONCLUSIONS: These results suggest that after TKA, the trunk movements of knee osteoarthritis patients were approximately equal to those of controls, with improvement in clinical outcomes such as knee extension limitation and pain. [ABSTRACT FROM AUTHOR]

BACKGROUND: There is a wide range of rehabilitation protocols after knee arthroscopic procedures, mainly based on specialist exercises. They comprise of specific stages and key moments but should also be individualized and adjusted to the patient's needs. OBJECTIVE: The aim of the study was to evaluate the BodyFlow device impact on physical and psychological functioning of the subjects after knee arthroscopy. METHODS: Ninety three patients were randomly divided into the study and control group. Each study group subject performed mild electrostimulation using the BodyFlow device for three weeks, five times a day for 20 minutes along with the standard rehabilitation protocol. Control group subjects were treated according to the standard rehabilitation protocol after knee arthroscopy. Healthy and operated lower limb size, a range of the knee joint motion, and the flexor and extensor strength were measured 3, 6, and 9 weeks after arthroscopy. At each measurement, the SF-36 and KOOS surveys were collected. RESULTS: On study day 21, a positive, statistically significant, difference in the knee joint size, range of flection and extension, flexor and extensor strength as well as all KOOS survey subscales and physical functioning categories included in the SF-36 survey was observed. On study day 63, positive effects persisted and significant differences in other categories included in the SF-36 survey were observed. CONCLUSION: Application of mild electrostimulation using the BodyFlow device has a positive impact on the swelling in the knee joint region, range of motion, extensor and flexor strength as well as physical, psychological, and social functioning. [ABSTRACT FROM AUTHOR]

BACKGROUND: Both isokinetic testing and functional tests are commonly used during the rehabilitation programme of individuals. Limited information exists in the literature, regarding the correlation between these two testing methods. OBJECTIVE: To determine the relationship among quadriceps and hamstrings isokinetic performance values and those derived from three functional assessment tests in a group of healthy participants. METHODS: Twenty-five men, were assessed via 1) three functional tests: single hop for distance (SHD), triple hop for distance (THD) and single timed hop (STH) and 2) isokinetic concentric bilateral knee flexion and extension strength values [Mean Peak Moment (MPM), Total Work (TW) and Average Power (AP)] at 60, 180 and 300 ∘ /s. RESULTS: Fair correlations were calculated between the bodyweight normalized scores of the functional tests and those of the normalized isokinetic variables. None of the three angular velocities and none of the three functional tests appeared to be more indicative to functional performance than the others. CONCLUSION: There is the need for dynamometry in conjunction with functional tests for a more comprehensive evaluation of knee extension and also flexion performance. [ABSTRACT FROM AUTHOR]

OBJECTIVE: The purpose of this systematic review with meta-analysis was to compare the effects of low load resistance combined with blood flow restriction (BFR) versus conventional quadriceps strengthening on knee symptoms and function as well as knee extensor strength and muscle thickness in adults with knee conditions. LITERATURE SURVEY: Guidelines based on the latest evidence highlight the importance of quadriceps strengthening to reduce pain and improve function in patients with knee conditions. Blood flow restriction is based on brief periods of vascular occlusion which cause muscle hypertrophy and increased strength. Before it can be recommended for individuals with knee conditions, quadriceps strengthening with low load resistance combined with BFR (LL-BFR) must show beneficial effects on clinical outcomes in addition to quadriceps strength and mass. METHODS: A systematic review with meta-analysis was conducted to identify relevant studies through PubMed, PEDro, and ScienceDirect up to January 2019. The protocol was registered on PROSPERO (CRD42019121306). Differences in pre- and post-intervention means and standard deviations were extracted to calculate the standardized mean difference for each intervention in each included study. SYNTHESIS: Eight studies were included. Limited evidence suggests that LL-BFR is more beneficial on quadriceps strength and thickness in patients with knee conditions than LL training alone or in addition to a rehabilitation program. Limited evidence indicates that LL-BFR training is equally effective in improving function and muscle thickness compared with a HL quadriceps strengthening program but elicits less knee pain, corresponding to additional benefits of 22 (95% confidence interval 1 to 43) mm on a 0–100 mm visual analogue scale. CONCLUSIONS: BFR could be a useful option for patients with knee conditions where conventional quadriceps strengthening program exacerbate knee symptoms. Future investigations should compare different BFR protocols to help establish better guidelines for clinicians. [ABSTRACT FROM AUTHOR]

BACKGROUND: The majority of common agility tests include pre-planned change of direction (COD) maneuvers which require muscular coordination. However, muscular coordination in terms of organization of co-activated antagonistic muscle pairs in COD maneuvers have not been studied. OBJECTIVE: To evaluate muscle coordination by analyzing co-contraction at knee and ankle during three agility tests and to investigate the relationships between muscle coordination and test completion time. METHOD: Thirteen healthy young male subjects (22.1 ± 1.9 years) participated in the study. Surface EMG and acceleration signals were used to calculate co-contraction index (CCI) for selected antagonistic muscle pairs of ankle and knee joints during COD maneuvers in agility tests. RESULTS: The findings indicated that concurrent activation costs a delay to complete the test faster. CCI was higher at right ankle and left knee and showed an increasing trend with advancing the phase when the test requires multiple CODs. CONCLUSIONS: Minimizing co-contraction would result in faster movement, however, there might be a trade-off between joint stiffness and test performance depending on changes in neuromuscular factors such as altered motor control strategies due to strength imbalances or occurrence of fatigue. [ABSTRACT FROM AUTHOR]

BACKGROUND: Although it is known that isokinetic knee extensor strength and balance ability are important, valid and reliable parameters, they have not been used hitherto to predict the performance of junior weightlifters. OBJECTIVE: To investigate the relationship among body composition, isokinetic knee extensor strength, balance, and weightlifting performance and to determine whether these factors predict competition performance in junior men weightlifters. METHODS: Fifty-one male junior weightlifters (age: 15.9 ± 1.2 years, height: 161.9 ± 7.7 cm, body mass: 62.7 ± 11.3 kg) participated in this study. Participants performed isokinetic knee extensor strength tests in concentric mode (at 60 and 180°/s) and balance tests (static and dynamic). Competition performance was calculated according to the Sinclair equation, which was used as the dependent variable in the statistical analysis. The extent to which the independent variables predicted competition performance was determined by bivariate correlations and multiple linear regression analysis. RESULTS: Significant correlations were found between the Sinclair score and the independent variables (r = 0.496-0.804, p < 0.05). Three models were fitted by hierarchical linear regression analysis. Body fat percentage was determined as a control variable in step one, isokinetic knee extensor strength at 180°/s was included in step two, and static balance was included in step three, with all three contributing to the models significantly (p = 0.0001, p = 0.0001, and p = 0.003, respectively). The variance of competition performance was explained by approximately 65% in step one, approximately 78% in step two, and approximately 82% in step three. CONCLUSIONS: The results of this study suggest that isokinetic knee extensor strength, static balance, and body fat percentage are effective for predicting competition performance in junior weightlifters. [ABSTRACT FROM AUTHOR]

BACKGROUND: Exercises that stretch the gastrocnemius (GCM) lead to greater ankle dorsiflexion (DF). GCM stretching combined with talar self-stabilisation has been reported to increase ankle DF range of motion (ROM). However, excessive subtalar and midtarsal pronation during GCM stretching may compensate for reduced ankle DF. Thus, this study examined the combined immediate effect of stretching GCM and stabilising talus and subtalar supination on limited ankle DF. OBJECTIVE: This study aimed to investigate the immediate effect of GCM stretching alone, GCM stretching with talar selfstabilisation and GCM stretching with talar self-stabilisation and subtalar supination on ankle kinematics in subjects with limited ankle DF. METHODS: Fifteen subjects with limited ankle DF were recruited. The subjects performed the three abovementioned methods. RESULTS: GCM stretching with talar self-stabilisation and subtalar supination significantly increased open-chain and closedankle DF ROM compared with GCM stretching alone. Moreover, GCM stretching combined with talar self-stabilisation and subtalar supination significantly increased open-chain ankle DF ROM with knee straight compared with pre-intervention (P < 0.017). CONCLUSIONS: The preferred method to increase ankle DF ROM is GCM stretching combined with talar self-stabilisation and subtalar supination. [ABSTRACT FROM AUTHOR]

BACKGROUND: The Hybrid Assistive Limb (HAL) is a robotic exoskeleton designed to support impaired limbs. OBJECTIVE: We aimed to evaluate whether active exercise using a single-joint HAL (HAL-SJ) following total knee arthroplasty can facilitate the recovery of knee flexion. METHODS: Twenty-two patients who underwent total knee arthroplasty were randomly allocated to the HAL-SJ group (n = 12) or conventional physical therapy (CPT) group (n = 10). On postoperative day 5, patients performed active knee flexion exercises either with or without HAL-SJ assistance every second day. Outcome measures included active and passive knee flexion range of motion (ROM), muscle strength, and pain intensity, as assessed by the visual analog scale, and were assessed on postoperative days 5 (pre-treatment) and 10 (post-treatment). Active ROM was measured at 6 months postoperatively; further long-term follow-up was performed by telephone interview. RESULTS: Both groups showed significant improvement between postoperative days 5 and 10 in all outcome measures. Improvements in active ROM (p < 0.01), passive ROM (p < 0.01), muscle strength (p < 0.01), and pain (p < 0.01) were significantly greater in the HAL-SJ group than in the CPT group. Long-term outcomes were also significantly better in the HAL-SJ group. CONCLUSIONS: HAL therapy enables patients to perform painless active movements and facilitates the recovery of knee function. [ABSTRACT FROM AUTHOR]

BACKGROUND: While Walkbot-assisted locomotor training (WLT) provided ample evidence on balance and gait improvements, the therapeutic effects on cardiopulmonary and psychological elements as well as fall confidence are unknown in stroke survivors. OBJECTIVE: The present study aimed to compare the effects of Walkbot locomotor training (WLT) with conventional locomotor training (CLT) on balance and gait, cardiopulmonary and psychological functions and fall confidence in acute hemiparetic stroke. METHODS: Fourteen patients with acute hemiparetic stroke were randomized into either the WLT (60 min physical therapy + 30 min Walkbot-assisted gait training) or CLT (60 min physical therapy + 30 min gait training) groups, 7 days/week over 2 weeks. Clinical outcomes included the Berg Balance Scale (BBS), Functional Ambulation Category (FAC), heart rate (HR), Borg Rating of Perceived Exertion (BRPE), Beck Depression Inventory-II (BDI-II), and the activities-specific balance confidence (ABC) scale. The analysis of covariance (ANCOVA) was conducted at P < 0.05. RESULTS: ANCOVA showed that WLT showed superior effects, compared to CLT, on FAC, HR, BRPE, BDI-II, and ABC scale (P < 0.05), but not on BBS (P = 0.061). CONCLUSIONS: Our results provide novel, promising clinical evidence that WLT improved balance and gait function as well as cardiopulmonary and psychological functions, and fall confidence in acute stroke survivors who were unable to ambulate independently. [ABSTRACT FROM AUTHOR]

BACKGROUND: An intensive task-oriented circuit training (TOCT) provides a valid approach in improving motor function in Multiple Sclerosis (MS). OBJECTIVE: We aimed at testing the efficacy of TOCT on gait kinematics in MS patients with mild-moderate disability. METHODS: Nineteen MS patients able of independent walking performed 3-D Gait Analysis before (TO) and after (Tl) a two-week TOCT program. Patients were clustered in two different subgroups, according to clinical neurological impairments assessed with specific functional system of Expanded Disability Status Scale (EDSS): pyramidal (Group 1) and cerebellar (Group 2) subjects. Spatio-temporal and kinematic data were compared before and after the TOCT intervention in the total sample of patients and in the two selected subgroups at two time intervals. RESULTS: Data obtained revealed increased dynamic ROM at knee joint after training in the whole study sample. Of note, knee dynamic excursion improved significantly in Group 1 but not in Group 2 patients after TOCT. Moreover, sagittal plane kinematics revealed significant modifications on knee and ankle biomechanics in Group 1 after rehabilitation. CONCLUSIONS: These data point out the benefits of the task specific training on gait dynamics in mild impaired MS subjects, linking to treatment opportunity in patients with a prevalent pyramidal impairment. [ABSTRACT FROM AUTHOR]

BACKGROUND: Many studies have investigated the correlation between muscle torque and joint position sense (JPS), but few studies have been performed on the correlation between torque ratio and JPS. OBJECTIVE: The aim of this study was to investigate JPS and muscle torque ratios of agonist and antagonist muscles in the ankle and knee joints of young adults. METHODS: A total of 38 right handed healthy participants, 12 males and 26 females, were recruited. All participants measured their peak torque of knee flexor/extensor and ankle dorsiflexor/plantar flexor by using a Biodex system. They also used the Biodex to assess the proprioception through active joint reposition sense test in knee and ankle joint. Peak torque of each muscle, agonist/antagonist torque ratio and JPS error were collected, and Pearson's correlation analysis was used to examine correlations between peak torque, torque ratio and JPS error. RESULTS: For knee joints, correlations were found between flexion and extension torque, extension torque and torque ratio, and torque ratio and JPS error (r = 0.825/ p = 0.000, r = - 0.482/ p = 0.002, and r = - 0.685/ p = 0.000, respectively). For ankle joints, correlations were found between dorsiflexion and plantar flexion torques, plantar flexion torque and torque ratio, plantar flexion torque and JPS, and torque ratio and JPS (r = 0.654/ p = 0.000, r = - 0.621/ p = 0.000, r = - 0.563/ p = 0.000, and r = - 0.761/ p = 0.000, respectively). CONCLUSIONS: JPS error of lower extremity joint may be more related with agonist/antagonist torque ratio rather than peak torque. Therefore, people who will have training for reducing JPS error need to consider torque ratio, too. [ABSTRACT FROM AUTHOR]

BACKGROUND: Many studies have presented lower limb kinematics in Western countries, but few have concentrated on gender and age differences for Chinese populations. OBJECTIVES: The purpose of this study was to investigate three-dimensional hip and knee kinematics especially for elderly Chinese during walking and running, as well as to analyze age differences. MATERIALS AND METHODS: Sixty healthy volunteers, including 40 young and 20 elderly adults, were divided into two groups by gender and instructed to perform walking and running in a comfortable manner. The hip and knee kinematics were obtained with 3D Motion Capture System. Normalization was used to avoid the body size effect. Age differences were tested with independent t -test (p < 0.05). RESULTS: In non-sagittal planes, the hip and knee ranges of motion of young males are larger during running, but smaller during walking than those of elderly males. Young females reveal smaller non-sagittal planes hip and knee ranges of motion than elderly females, regardless of whether they are walking or running. There are also significant age differences in the peak hip and knee angles especially in frontal plane during running. Young adults reveal greatly higher peak hip and knee adduction angles than elderly adults. CONCLUSIONS: Walking speed and the hip and knee ROM for Chinese are different from Westerners. These kinematic differences can be used for reference to design better joint prostheses to meet various Chinese people's needs. [ABSTRACT FROM AUTHOR]

BACKGROUND: Individuals may suffer from repeated sprints-induced muscle damage, which could lead to a prolonged recovery period, thereby influencing subsequent closely-scheduled training or competitions. OBJECTIVE: To examine whether an initial muscle-damaging sprint exercise could confer a protective effect against muscle damage induced by the subsequent identical exercise performed four days later. METHODS: Fourteen physically-active men completed two sprinting bouts (15 sets of 30-m maximal sprints) with 4 days apart. Before, 24, 48, and 72 hours after both bouts, muscle damage markers were measured. In addition, time trial, along with the peak heart rate (HR) and rating of perceived exertion (RPE) during each sprint set were also recorded. RESULTS: Comparing to the initial bout, less muscle soreness and faster recoveries of the knee flexion eccentric peak torque and angle of peak torque were found following the second bout. In addition, the time trial and HR for each sprint set were not different between the two bouts, but the average RPE was less during the second bout (p = 0.013). CONCLUSIONS: The protective effect from the exposure to the initial sprint was evident. Thus, repeated exposures to the sport-specific sprints can positively influence the symptoms of muscle damage without influencing the sprinting performance. [ABSTRACT FROM AUTHOR]

BACKGROUND: Many different squatting techniques have been recommended, but few studies tried to identify how different muscle groups contributed to this movement in each technique. OBJECTIVE: To compare the electromyographic activation (EMG) of the thigh, hip and trunk muscles during maximal voluntary isometric contractions in the back and front squat performed in different degrees of knee flexion, while also comparing the levels of force produced during different ranges of motion. METHODS: Ten healthy men (30.7 ± 7.9 years), regularly practicing strength training, performed maximal isometric actions during back and front squats, at 60 ∘ , 90 ∘ and 120 ∘ degrees of knee flexion. The electromyographic activity of the rectus femoris, vastus lateralis, vastus medialis, biceps femoris, gluteus maximus, and erector spinae was recorded. RESULTS: At 60 ∘ a lower EMG activation in both squats was observed although this depth showed the highest levels of maximal voluntary isometric strength. Increasing knee flexion to 120 ∘ did not result in greater muscle activation. Only at 90 ∘ there was no significant difference in EMG activity between the front and back squat. CONCLUSIONS: A greater squat depth did promote a decrease in EMG activity When executed in isometric contraction, parallel squatting offers better ratio of force X recruitment of primary motor muscles. Therefore, this amplitude can be used in training or rehabilitation strategies, both in frontal and posterior variations (with higher level of strength), observed the most convenient option for the practitioner. [ABSTRACT FROM AUTHOR]

BACKGROUND: Strengthening exercises help improve physical function and muscle strength in knee osteoarthritis (OA). However, optimal exercise programmes for treating knee OA remain unclear. OBJECTIVE: : To compare efficacy of isometric exercises performed at different angles and isokinetic exercises in patients with knee OA. METHODS: Patients were randomly divided into two groups. For four weeks, Group I (n = 15) and II (n = 17) patients with grade 2–4 performed isokinetic and isometric exercises at several different angles, respectively. Flexor and extensor knee muscle strengths were measured. Pain and physical function were assessed using VAS, WOMAC, the Lequesne Index and SF-36. All parameters were recorded at three time points: baseline (T0), after treatment (T1) and at 10-week follow-up (T2). RESULTS: VAS on movement, WOMAC, Leuqesne and SF-36 physical scores improved from T0 to T2 within each group, but Grade 3 and Grade 4 patients in the Group I showed better results compared with Group II at T2. Isokinetic exercise yielded higher extensor PM values than its isometric counterpart at T2 (P < 0.05) at 180 ∘ /s for Grade 2 and Grade 3 patients. CONCLUSIONS: Both isokinetic and isometric exercises were effective in the treatment of knee OA of all grades in terms of pain reduction and functional improvements. However, isokinetic exercise produced longer lasting effects than isometric exercise. [ABSTRACT FROM AUTHOR]

OBJECTIVES: To compare pelvis, hip and knee kinematics during gait and extensibility of hip muscles between low back pain (LBP) and asymptomatic subjects. METHODS: Forty adult volunteers (11 men and 29 women) between 18 to 30 years from university population were included in this study. Twenty patients with LBP formed the LBP group, and 20 asymptomatic subjects formed the control group. Pelvic tilt and knee valgus, peak hip and knee joint excursion, and temporo-spatial variables were assessed during gait with Kinovea software. Extensibility of hip muscles was measured by Active Knee Extension test (AKE), modified Ober test, and Thomas test. RESULTS: There was a significant increase in pelvic tilt (p < 0.01), valgus angle (p < 0.01), and a significant decrease in hip extension (p < 0.01) in the LBP group compared to the control group. There was a significant decrease in extensibility of the hip flexors (p < 0.05) of the dominant leg and in the hip abductors (p < 0.01) in the LBP group compared to the control group. CONCLUSIONS: The findings of this study suggest that non-specific mechanic LBP patients present differences in the pelvis, hip and knee kinematics in sagittal and frontal plane during gait and less hip flexors and abductors muscles extensibility compared to asymptomatic subjects. [ABSTRACT FROM AUTHOR]

BACKGROUND: In the current literature, exercises performed using fitness equipment and body weight have been used in order to decrease the bilateral deficit (BLD) and increase the hamstring-quadriceps (H/Q) ratio. No studies have previously investigated the effect of therabands, which are both portable and practical to be used anywhere, in regard to the BLD and H/Q ratio. OBJECTIVES: The purpose of this study was to investigate the effect of several 10-week lower extremity exercises performed through therabands on the BLD and H/Q ratio. METHODS: Twenty-seven voluntary male soccer players participated in the study. The players were categorized into the control group (CG) (n = 14) and the theraband exercise group (TBG) (n = 13). Theraband exercises for the lower extremity were performed by the soccer players in the TBG for four days every week over a 10-week period. The dominant (D) and non-dominant (ND) leg concentric extension and flexion of the soccer players were determined through an isokinetic dynamometer at 30 ∘ s - 1 and 240 ∘ s - 1 angular velocities. The data were analyzed through SPSS 24. To determine the difference between the BLD, H/Q ratios, and pre- and post-test of peak torque (PT), the Wilcoxon test was employed. RESULTS: As a result of the analysis, it was found that the BLD for the TBG decreased, which was statistically significant (p < 0.05), whereas there were no statistically significant differences for the H/Q ratio for both the CG and TBG; the D and ND leg H/Q rate of the TBG at 240 ∘ s - 1 angular velocity increased in the post-test. CONCLUSIONS: It was found that the exercises performed with the theraband were extremely efficient at increasing the PT and decreasing the BLD. [ABSTRACT FROM AUTHOR]

BACKGROUND: Deep knee bending has been reported as an occupational hazard to workers who have to adopt such postures. High knee joint moments have been associated with knee osteoarthritis initiation and progression. OBJECTIVE: This study aimed to compare four high knee flexion postures (dorsiflexed and plantarflexed kneeling, and flat-foot and heels-up squatting) to determine which one results in lower knee joint flexion and ab/adduction moments. METHODS: Forty-three participants performed five trials of each posture. Peak (for descent/ascent) and mean (for the static hold) external knee flexion and ab/adduction moments were analyzed for each posture using 2-way ANOVAs and post-hoc pairwise comparisons. RESULTS: It was observed that the flat-foot squat resulted in significantly lower knee flexion moment compared to the other three postures (4.63±0.99 % BW·H during the static phase, and 5.83±1.24 % BW·H and 5.94±1.24 % BW·H during descent and ascent phases, respectively). During ascent phase, significant differences was indicated in peak adduction moments for the flat-foot squat in comparison to both styles of kneeling. CONCLUSIONS: When high knee flexion is required but posture is not dictated, flat-foot squat will reduce exposures to high knee moments. [ABSTRACT FROM AUTHOR]

BACKGROUND: Basketball players playing for the University of Hawai'i Hilo are subjected to well above normal physiological and psychogenic stressors with their exposure to significant amounts of easterly-bound air travel that include time zone and seasonal changes throughout one season. OBJECTIVE: The aim of this study was to investigate the effects of a basketball season on physiological, anthropometrical, biometric markers, strength and power of men's collegiate basketball team who play their away matches after a relatively long (up to 6 h) eastward flight. METHODS: Thirty-six men collegiate basketball players and a control group of thirty-seven university students, were included in this study. Measurements were commenced at the beginning of the season and concluded immediately post-season. RESULTS: Post-season, players presented with significant gains for resting levels of salivary cortisol; significant gains in visceral trunk fat, total body fat percent or body weight, in resting heart rate and mean arterial blood pressure; and diminishment in leg muscle isokinetic force, most noticeably in knee flexion strength. Vertical jump height also decreased significantly post-season. These changes were not found in the control group. CONCLUSION: A flight-travel-heavy basketball season resulted in broad-spectrum declinations in variables related to overall health and well-being in men collegiate basketball players. It is concluded that the prolonged intermittent stress of such a season resulted in measureable stress such as increased cortisol levels, increased blood pressure and heart rate, and selective increase in visceral trunk fat, total percent body fat thus total body weight. [ABSTRACT FROM AUTHOR]

BACKGROUND: Ankle braces are commonly used to protect ankle joints from a sprain by restricting inversion. However, the difference between a soft brace (SB) and a semi-rigid brace (SRB) regarding kinematic and kinetic changes of the lower limb joints after forward and lateral drop landing is unknown. OBJECTIVE: The aim of this study was to evaluate the effect of SB and SRB, on kinematic and kinetic changes after each drop landing in healthy young women. METHODS: Ten female adults were assessed for one leg while wearing SB, SRB or non-brace (NB). For assessing kinematic and kinetic changes after drop landing, the participant jumped and landed forward and laterally with one leg on a force platform. Knee and ankle joint angle and moment, peak ground reaction force (pGRF), time to peak GRF (TpGRF), the rate of force development (RFD) and GRF impulse (impulse) were measured. RESULTS: The results indicated that knee flexion angle, TpGRF, RFD, and impulse were significantly different between SRB and NB after forward drop landing. SRB demonstrated significant increases in RFD and decreases in impulse. CONCLUSIONS: Semi rigid brace may be beneficial in providing more restriction to the ankle joint for preventing ankle sprains during landing. [ABSTRACT FROM AUTHOR]

BACKGROUND: : Although whole body electromyostimulation (WB-EMS) has been shown to improve body composition and muscle strength in several research studies, it has not been confirmed whether a dose-response effect using various impulse-intensities exists and how they affect adipose tissue-derived adipokines (APK), body composition, and strength. OBJECTIVE: To investigate the dose-response effect of wearing a WB-EMS suit in conjunction with isometric exercise on adipokines (APK), body composition including thigh circumference, and thigh muscle strength in normal healthy men for 6 weeks. METHOD: Fifty-two male subjects were randomly assigned to one of four groups: control group (CON, n = 13), low impulse-intensity (LII) group (n = 12), mid impulse-intensity (MII) group (n = 14), and high impulse-intensity (HII) group (n = 13). Low-, mid- and high-impulse intensities were set at 50%, 60% and 80% of maximum tolerance (1MT). Subjects in CON group wore WB-EMS suits, but did not receive any impulses. The WB-EMS suits used in this study enabled the simultaneous activation of eight muscle groups with selectable intensities. Stimulation frequency was selected at 85 Hz, impulse-width at 350 microsecond, and impulse-rise as a rectangular application. Impulse duration was 6 s with a 4 s break between impulses. The 20-minute WB-EMS sessions were combined with isometric exercises 3 times a week for 6 weeks. APK, body composition including thigh circumference, and isokinetic peak moment (PT) and work per repetition (WR) of the knee extensors and flexors were measured on Week 0, Week 2, Week 4, and Week 6. RESULTS: Compared with the CON group, 1) there was a significant group by time interaction difference in Resistin (P = 0.016). That is, Resistin increased in the CON and LII groups, but decreased in the MII and HII groups. These changes in Resistin for both groups began to appear at Week 4. 2) Body weight (P = 0.024) and muscle mass (P = 0.037) were significantly different in group by time interaction. The decrease of body weight in the HII group began to appear at Week 4. In particular, the level of muscle mass increased only in the HII group at Week 6. 3) There were significant group by time interaction differences in the circumferences of thigh subcutaneous fat (TSF) and thigh total fat (TTF) on right and left sides. The right TSF (P = 0.045) and TTF (P = 0.019) decreased from baseline to Week 6 in the HII group. These changes were similar to the left TSF (P = 0.038) and TTF (P = 0.011). The changes in the HII group showed a marked decrease at Week 6. 4) There were significant group by time interaction effects in the PT of the left knee extensor (P = 0.037) and PT of the right knee flexor (P = 0.012). These results were similar with the WR of the right knee flexor (P = 0.002) and the WR of the left knee flexor (P = 0.019) in the HII group, which were significantly higher than those of the other three groups at Week 4 and 6. CONCLUSIONS: WB-EMS administered at high impulse intensity can improve Resistin, body composition including thigh circumference, and isokinetic strength in healthy men after approximately 4 to 6 weeks. [ABSTRACT FROM AUTHOR]