Reliability of Goniometric Techniques for Measuring Hip Flexor Length Using the Modified Thomas Test.

Background: The modified Thomas test (MTT) is commonly used to assess the flexibility of hip musculature, including the iliopsoas, rectus femoris, and tensor fascia latae. This measurement is important to include in a comprehensive musculoskeletal examination. However, existing research shows conflicting results regarding its reliability, particularly due to variations in controlling pelvic tilt during testing, which may lead to inaccurate measurements of hip extension when quantifying the test outcomes. Purpose/Hypothesis: This study aimed to evaluate the intra- and inter-rater reliability of the Modified Thomas Test (MTT) in assessing hip flexor length using a goniometer. It was hypothesized that controlling for pelvic tilt would enhance the reliability of these measurements. Study Design: Intra- and inter-rater reliability study. Methods: Sixty-four healthy individuals were recruited to participate in this study. The MTT was performed twice on each leg by both an experienced and a student physical therapist. Blinded goniometric measurements for hip extension range of motion (ROM) in the MTT position were taken with neutral pelvic tilt being enforced via palpation. A double-blind protocol was used where both examiners were unaware of each other's measurements and the goniometer was covered to blind the measuring therapist to the values as well. ROM values were entered into a Microsoft Excel spreadsheet and quantified using SPSS software. Statistical analysis included calculating Intraclass Correlation Coefficients (ICCs) and Standard Errors of Measurement (SEMs) using SPSS software. Results: The study included 64 participants (mean age = 23.7 ± 4.34 years). The MTT demonstrated high intra-rater reliability (ICC = 0.911) and inter-rater reliability (ICC = 0.851). The SEMs indicated minimal variability around the mean scores. The average hip extension ROM measured was 5.43± 9.73 degrees. Conclusion: These results suggest that the MTT is a reliable tool for assessing hip flexor length in clinical practice, particularly when pelvic tilt is controlled. These results have important implications for accurately testing orthopedic limitations that can contribute to low back, hip, and knee pain. Level of Evidence: 3.

Real-Time Visual Kinematic Feedback During Overground Walking Improves Gait Biomechanics in Individuals Post-Stroke.

Treadmill-based gait rehabilitation protocols have shown that real-time visual biofeedback can promote learning of improved gait biomechanics, but previous feedback work has largely involved treadmill walking and not overground gait. The objective of this study was to determine the short-term response to hip extension visual biofeedback, with individuals post-stroke, during unconstrained overground walking. Individuals post-stroke typically have a decreased paretic propulsion and walking speed, but increasing hip extension angle may enable the paretic leg to better translate force anteriorly during push-off. Fourteen individuals post-stroke completed overground walking, one 6-min control bout without feedback, and three 6-min training bouts with real-time feedback. Data were recorded before and after the control bout, before and after the first training bout, and after the third training bout to assess the effects of training. Visual biofeedback consisted of a display attached to eyeglasses that showed one horizontal bar indicating the user's current hip angle and another symbolizing the target hip extension to be reached during training. On average, paretic hip extension angle (p = 0.014), trailing limb angle (p = 0.025), and propulsion (p = 0.011) were significantly higher after training. Walking speed increased but was not significantly higher after training (p = 0.089). Individuals demonstrated a greater increase in their hip extension angle (p = 0.035) and propulsion (p = 0.030) after the walking bout with feedback compared to the control bout, but changes in walking speed did not significantly differ (p = 0.583) between a control walking bout and a feedback bout. Our results show the feasibility of overground visual gait feedback and suggest that feedback regarding paretic hip extension angle enabled many individuals post-stroke to improve parameters important for their walking function.

A portable visual biofeedback device can accurately measure and improve hip extension angle in individuals post-stroke.

BACKGROUND: Visual biofeedback has shown success in improving gait mechanics in individuals post-stroke but has typically been restricted to use on a treadmill or a short walkway. Using real-time visual biofeedback during overground walking could increase the ease of clinical translation of this method. The objective was to investigate the reliability of a real-time hip extension feedback device during unconstrained, overground walking. We hypothesized that the peak hip extension angle outcome of our device would be comparable to peak hip extension angle measured from a common motion capture system. In addition, we hypothesized that individuals post-stroke would increase their hip extension angle after a single walking bout with visual biofeedback of their hip extension angle. METHODS: Fourteen individuals with chronic stroke walked for one six-minute walking bout with the visual biofeedback device. Before (pre-training) and after (post-training) the feedback walking bout, participants walked in a straight line at their self-selected speed for at least five steps per foot. FINDINGS: Our device was reliable in measuring peak hip extension angle when compared to 3D motion capture equipment (R2 = 0.99). Individuals increased their hip extension angle after one session with the visual biofeedback (+2.886 ± 2.189 deg) compared to a control walking bout (+1.550 ± 1.629 deg) (Z = -2.103, p = 0.035). INTERPRETATION: Our novel and inexpensive biofeedback method may provide benefit for individuals post-stroke and expand the possibilities for feedback in rehabilitation.

The Effects of Kinesio Taping® on Muscle Interplay within the Lumbo-Pelvic-Hip Complex: A Randomized Placebo-Controlled Trial.

Coordination of muscle activity is determined by the recruitment order of agonists and synergists that results from their onset times. Motor recruitment deficits are possible. This study examined the acute and prolonged effects of three different techniques of the kinesio taping method in optimizing the intermuscular coordination within the lumbo-pelvic-hip complex. The sample consisted of 56 healthy participants of both genders, randomly divided into equal groups by kinesio taping muscle facilitation, muscle inhibition and functional correction technique, and placebo kinesio taping condition. The onsets of the ipsilateral and contralateral erector spinae muscles, in relation to the semitendinosus muscle of the tested leg, were measured using the surface electromyography, during the active performance of the prone hip extension test. Time span was also determined. Measurements were performed at baseline, 60 min, and 48 h post-intervention. For the control group, we did not find statistically significant differences in the onset between the measurement points (p > 0.05), while in the experimental groups, there was a significant delay in the onset of the contralateral erector spinae (p < 0.001) in the second and third measurement points. These results indicate that the kinesio taping method can optimize the intermuscular coordination, with the potential for primary injury prevention.

A preliminary study of the reliability and validity of the Posterior Standing Overhead Arm Reach (SOAR) test as a measure of functional hip extension motion.

BACKGROUND: Current clinical tests do not provide a method to reliably measure closed chain hip extension. We developed the Posterior Standing Overhead Arm Reach (SOAR) test for this purpose. OBJECTIVES: This was a preliminary intrarater and interrater reliability and validity study of the Posterior SOAR test as a measure of functional hip extension. DESIGN: Cross-sectional. METHOD: Hip extension on the Posterior SOAR test was measured with a standard goniometer independently by two examiners. The test was then repeated using three-dimensional (3D) motion capture. Intraclass correlation coefficients (ICC) were used to determine the intrarater and interrater reliability of the goniometric measure and Pearson correlations were used to assess the relationship between measures obtained via goniometry and 3D motion capture. RESULTS: Fifty hips were assessed in 25 (14 female, 11 male) asymptomatic participants (mean age = 24.0 years, SD = 1.1). Intrarater reliability (ICC2,3) was 0.80 (95% CI = 0.68-0.88) for Examiner 1 and 0.77 (95% CI = 0.64-0.86) for Examiner 2, indicating excellent reliability. The standard error of the measure (SEM90) ranged from 2.5° to 3.0° with a minimal detectable change (MDC90) of 3.5° to 4.2°. Interrater reliability was good with ICC = 0.65 (95% CI = 0.36-0.80). Pearson correlations were significant with low to moderate associations (r = 0.36, P = 0.009; r = 0.51, P < 0.001). CONCLUSIONS: The Posterior SOAR test demonstrated excellent intrarater reliability, good interrater reliability, and low to moderate associations with 3D motion capture. The Posterior SOAR test has the potential to provide a reliable and accurate assessment of closed chain hip extension.

Hip physical examination extension loss and radiographic osseous findings in patients with low back pain and nonarthritic hips.

The association between hip and spine abnormalities is frequent, and limitation in hip extension has been linked with low back pain. The purpose of this study was to assess the radiographic osseous findings in nonarthritic hips of patients with hip pain, low back pain, and limited hip extension. Ninety patients (92 hips) were included in this study. Hip extension was tested in the contralateral decubitus position with the hip in neutral abduction/adduction and neutral rotation. In sequence, hip extension was tested by adding passive abduction, followed by internal/external rotation of the hip. A hip extension limitation was defined as less than zero degrees of extension. Imaging studies were assessed for the following osseous morphologies: decreased ischiofemoral space (≤17 mm), increased femoral torsion (≥30°), decreased femoral torsion (≤5°), and posterior acetabular overcoverage. Fifty-seven out of 92 hips (62%) had at least one osseous imaging finding for limitation in hip extension: decreased ischiofemoral space (38/92, 41%), increased femoral torsion (5/92, 5%), decreased femoral torsion (24/92, 26%), and posterior acetabular overcoverage (21/92, 23%). Decreased ischiofemoral space, femoral torsional abnormalities, and/or posterior acetabular wall overcoverage are observed in imaging studies of most individuals with limitation of hip extension and low back pain.

Electromyographic differences of the gluteus maximus, gluteus medius, biceps femoris, and vastus lateralis between the barbell hip thrust and barbell glute bridge.

Hip extensor muscles are critical to sport performance as events requiring sprinting and forceful landings are highly dependent on these muscles. Despite biomechanical differences between the barbell hip thrust (BHT) and the barbell glute bridge (BGB), both are biomechanically efficient ways to load this musculature for training purposes. Research investigating the differences in muscular activity between the BHT and BGB has yet been conducted. The aim of this study was to investigate, through surface electromyography, if one exercise is more optimal than the other in producing greater muscle activation for specific hip extensor muscles. Ten male participants completed a two-part study protocol. Results revealed the BHT elicited significantly greater muscle activity within the vastus lateralis for peak and mean outcomes; however, the BGB elicited significantly greater muscle activity in the upper and lower gluteus maximus for peak and mean outcomes and mean outcome in the gluteus medius. Current findings suggest, the BGB is, at minimum, a superior substitute for the BHT for eliciting a larger magnitude of activity in the gluteus maximus. Future studies between the two exercises are warranted to discern which produces greater hypertrophy and whether adaption of the BHT or BGB transfers more optimally to sport performance.

Effects of Back-Support Exoskeleton Use on Lower Limb Joint Kinematics and Kinetics During Level Walking.

We assessed the effects of using a passive back-support exoskeleton (BSE) on lower limb joint kinematics and kinetics during level walking. Twenty young, healthy participants completed level walking trials while wearing a BSE (backXTM) with three different levels of hip-extension support torque (i.e., no torque, low, and high) and in a control condition (no-BSE). When hip extension torques were required for gait-initial 0-10% and final 75-100% of the gait cycle-the BSE with high supportive torque provided ~ 10 Nm of external hip extension torque at each hip, resulting in beneficial changes in participants' gait patterns. Specifically, there was a ~ 10% reduction in muscle-generated hip extension torque and ~ 15-20% reduction in extensor power. During the stance-swing transition, however, BSE use produced undesirable changes in lower limb kinematics (e.g., 5-20% increase in ankle joint velocity) and kinetics (e.g., ~ 10% increase in hip flexor, knee extensor, and ankle plantarflexor powers). These latter changes likely stemmed from the need to increase mechanical energy for propelling the leg into the swing phase. BSE use may thus increase the metabolic cost of walking. Whether such use also leads to muscle fatigue and/or postural instability in long-distance walking needs to be confirmed in future work.

The inter-rater reliability of clinical observation of prone hip extension and association between aberrant movement and chronic low back pain.

BACKGROUND: Clinical observation of aberrant movement patterns during prone hip extension (PHE) is commonly used in clinical practice to identify patients with low back pain. It could be clinically useful to identify individuals with chronic low back pain during remission (CLBPremission) to provide proactive intervention to prevent exacerbation of low back symptoms. OBJECTIVES: This study aimed to establish inter-rater reliability of clinical observation of PHE and association between aberrant movement pattern and CLBPremission. DESIGN: A cross-sectional study. METHOD: Twenty-six participants with CLBPremission and 18 participants without history of low back pain (NoLBP) performed 3 repetitions of active PHE, while 2 examiners concurrently observed and independently rated the movements as "presence" or "absence" of aberrant movement. Kappa statistics were used to establish inter-rater reliability based on rating data from 2 examiners, while chi-square tests were used to determine the association between aberrant movement and CLBPremission based on ratings (presence and absence) and known groups (CLBPremission and NoLBP). RESULTS: Kappa values ranged from fair to moderate (Kappa = 0.36-0.58). Result also demonstrated a significant association (P < 0.05) between presence of aberrant movement and CLBPremission. Findings indicate fair to moderate inter-rater reliability which are sufficient for clinical practice. The findings also indicated presence of aberrant movement patterns during active PHE was associated with CLBPremission. CONCLUSIONS: These findings suggested the usefulness of clinical observation of aberrant movement pattern during PHE to identify CLBPremission. The detection of aberrant movement would help clinicians to provide preventive program to minimize the risk of recurrent episodes of low back symptoms.

Hybrid Assistive Limb improves restricted hip extension after total hip arthroplasty.

The Hybrid Assistive Limb (HAL) was developed as an exoskeleton robot that supports gait training. The purpose of this study was to assess the usefulness of training using the HAL after total hip arthroplasty (THA). We targeted 16 consecutive patients who underwent THA via the posterior approach. We randomized patients to the HAL group (8 hips), in which the HAL was used as part of physical therapy, or the control group (8 hips), in which only typical physical therapy was performed. Gait analysis was performed before and after surgery, and comparisons were made between the two groups. We evaluated the single support time (%), double support time (%), cadence (steps/min), velocity (cm/s), stride length (cm), and anteroposterior and lateral variability, and assessed the hip and knee joint range of motion in the sagittal plane. The results showed improvements in the hip extension angle and other gait parameters in the HAL group. Among gait-related problems after THA, a decreased peak hip extension angle is reported to be a significant factor that affects gait disability. This study revealed that HAL usage after THA seems to be a useful method to obtain sufficient extension angle.

Effects of abdominal drawing-in maneuver with or without prior iliopsoas stretching on gluteus maximus activity during prone hip extension.

BACKGROUND: Prone hip extension (PHE) has been investigated to strengthen the hip joint and back extensor muscles. However, it has not been compared with various PHE exercises in individuals with iliopsoas shortness. OBJECTIVE: This study compared pelvic compensation and hip and back extensor muscle activities in individuals with iliopsoas shortness during prone hip extension (PHE) using the abdominal drawing-in maneuver alone (PHEA) and after iliopsoas stretching (PHEAS). METHODS: Twenty-five individuals with iliopsoas shortness were included in the study. Electromyography was used to investigate bilateral erector spinae (ES) and ipsilateral gluteus maximus (GM), biceps femoris (BF), and semitendinosus (ST) muscles during PHE, PHEA, and PHEAS. Pelvic anterior tilting and rotation angles were measured during each PHE exercise via electromagnetic motion tracking. A modified Thomas test was used to examine the hip extension angle before and after iliopsoas stretching. One-way repeated-measures analysis of variance was used to investigate differences in pelvic anterior tilting and rotation angle and in hip and back extensor muscle activities among PHE, PHEA, and PHEAS. The level of statistical significance was set at α= 0.01. RESULTS: GM muscle activity was significantly greater with PHEAS, compared to PHE and PHEA (p< 0.01). Bilateral ES and ipsilateral BF and ST muscle activities were significantly reduced with PHEAS, compared to PHE and PHEA (p< 0.01). Anterior pelvic tilting and rotation angles were significantly reduced with PHEAS, compared to PHE and PHEA (p< 0.01). CONCLUSIONS: PHEAS is recommended to selectively strengthen GM muscles with minimal BF and ST muscle activities and pelvic compensation in individuals with iliopsoas shortness. The abdominal drawing-in maneuver (ADIM) after iliopsoas stretching is more efficient than ADIM alone during PHE, especially in individuals with iliopsoas shortness.

Superimposing hip extension on knee flexion evokes higher activation in biceps femoris than knee flexion alone.

Hamstring muscle function during knee flexion has been linked to hamstring injury and performance. However, it is unclear whether knee flexion alone (KF) requires similar hamstring electromyography (EMG) activity pattern to simultaneous hip extension and knee flexion (HE-KF), a combination that occurs in the late swing phase of sprinting. This study examined whether HE-KF maximal voluntary isometric contraction (MVIC) evokes higher (EMG) activity in biceps femoris long head (BFlh) and semitendinosus (ST) than KF alone. Effects of shank rotation angles were also tested. Twenty-one males performed the above-mentioned MVICs while EMG activity was measured along ST and BFlh. Conditions were compared using a one-way mixed functional ANOVA model under a fully Bayesian framework. Higher EMG activity was found in HE-KF in all shank rotation positions than in KF in the middle region of BFlh (highest in the 9th channel, by 0.022 mV [95%CrI 0.014 to 0.030] in neutral shank position). For ST, this was only observed in the neutral shank position and in the most proximal channel (by 0.013 mV [95%CrI 0.001 to 0.025]). We observed muscle- and region-specific responses to HE-KF. Future studies should examine whether hamstring activation in this task is related to injury risk and sprint performance.

Double Diapering Ineffectiveness in Avoiding Adduction and Extension in Newborns Hips.

Hip flexion and abduction is fundamental for developmental dysplasia of the hip (DDH) treatment. At present, double diaper treatment has been inappropriately adopted when DDH is suspected. The aim of this study was to verify whether double diapers influence a newborn's hip position. Here, we studied 50 children (23 female; 27 male; average age 62.33 ± 20.50 days; average birth weight 3230 ± 447 g) with type I hips according to Graf. At the same time of the ultrasound (US) examination, the following hip positions were measured using a manual protractor: (1) spontaneous position, supine on the outpatient bed without a diaper; (2) spontaneous position, with a double diaper; and (3) squatting position on the caretakers' side. Statistical analysis was performed with a t-test to compare between (1) the spontaneous position without a diaper and with double diapers; (2) the spontaneous position with double diapers as well as the squatting position on the caretakers' side with a diaper. The comparison between the hip position without diaper and with double diapers was statistically not significant for all measurements, i.e., right hip flexion (p < 0.33), left hip flexion (p < 0.34), and right and left hip abduction (p < 0.87). The comparison between the hip position with double diapers and on the caretakers' side was statistically significant for all measurements, i.e., right hip flexion (p < 0.001), left hip flexion (p < 0.001) and right and left hip abduction (p < 0.001). We found that the use of double diapers did not affect hip position, while the position formed on the caretaker's side shows favorable influence.

Trunk and lower limb muscularity in sprinters: what are the specific muscles for superior sprint performance?

OBJECTIVE: The major purpose of this study was to determine the specific muscle(s) for superior sprint performance in sprinters. The cross sectional areas (CSAs) of ten muscles of the trunk and lower limb were measured using magnetic resonance images in 56 male sprinters and 40 male non-sprinters. In addition to the absolute CSA, to minimize the effect of difference in body size among participants, the relative CSA normalized to body mass was used for analysis of this study. RESULTS: Absolute and relative CSAs of most trunk and lower limb muscles, including the psoas major (PM) and gluteus maximus (GM), were significantly larger in sprinters than in non-sprinters (all P < 0.001, d = 0.91 to 1.82). The absolute and relative CSAs of the PM and GM correlated significantly with personal best 100-m sprint time in sprinters (r = - 0.363 to - 0.388, all P < 0.01). A stepwise multiple regression analysis revealed that both CSAs of absolute PM and relative GM were predictive variables for the personal best 100 m sprint time in sprinters (ß = - 0.289 and - 0.287, respectively, both P < 0.05). These findings suggest that the PM and GM may be specific muscles for superior sprint performance in sprinters.

Comparison of the electromyographic recruitment of the posterior oblique sling muscles during prone hip extension among three different shoulder positions.

Objective: We examined the effects of three different shoulder positions on the electromyography (EMG) activity of the posterior oblique sling and pelvic rotational angle during right prone hip extension (PHE).Methods: Fifteen healthy males (mean age, 25.4 ± 1.2 years) participated in this study. Three different left shoulder positions (0°, 90°, 125° of abduction) were assessed during right PHE. Surface EMG signals were recorded for the left latissimus dorsi, left middle trapezius, left lower trapezius, lumbar multifidus, right gluteus maximus, and right biceps femoris. An electromagnetic tracking motion analysis device was used to monitor compensatory pelvic rotation during right PHE. Significant differences in muscle activity and pelvic rotation angle among the three different shoulder abductions were assessed using one-way repeated measures analysis of variance and the Bonferroni post hoc test.Results: The bilateral multifidus and right gluteus maximus EMG amplitudes increased with increasing shoulder abduction angle during PHE (padj < 0.01). The degree of pelvic rotation during PHE decreased with increasing shoulder abduction angle (padj < 0.01).Conclusions: We found that PHE with 125° of left shoulder abduction increased the selective activation of lumbopelvic stabilizing muscles such as the multifidus and gluteus maximus.

Prediction equation of hip external rotators maximum torque in healthy adults and older adults using the measure of hip extensors maximum torque.

BACKGROUND: The use of predictive equation of muscular torque can reduce physical effort and time spent during evaluation. OBJECTIVES: To establish, validate, and test the accuracy of a prediction equation to estimate the hip external rotators (HER) torque in adults and older adults by means of hip extensors (HEX) torque measurement. METHODS: Eighty-three healthy adults (development set) were assessed to test the association of HEX and HER torques and to establish the prediction equation. A separate 36 adults and 15 older adults (validation sets) were assessed to test the ability of the equation to estimate HER torque. Hip isometric strength was assessed by a handheld dynamometer. RESULTS: Simple linear regression analysis revealed that HEX torque was associated with HER torque (r=0.80; p<0.0001), resulting in the following prediction equation: HERtorque=-0.02+(0.58 * HEXtorque). Paired t-test revealed no difference between directly measured and predicted values of HER torque in adults (mean difference=0.02; 95% CI=-0.115, 0.072) and older adults (mean difference=0.05; 95% CI=-0.02, 0.12). CONCLUSION: The HEX and HER torques were strongly correlated. The prediction equation was valid, accurate, and can be used to estimate HER muscle strength in healthy adults and older adults, requiring only the direct measurement of HEX torque.

Prolonged sitting and physical inactivity are associated with limited hip extension: A cross-sectional study.

BACKGROUND: It is possible that physical inactivity and prolonged sitting could lead to changes in muscle properties or bony limitations which may reduce passive hip extension. OBJECTIVES: This study explored the association between passive hip extension and sitting/physical activity patterns. DESIGN: Cross sectional study. METHOD: The modified Thomas Test is a clinical test used to characterise hip flexion contracture. This test was used to measure passive hip extension across 144 individuals. In addition, sitting behaviours and physical activity patterns were quantified using the Global Physical Activity Questionnaire. Cut off points were defined for low/high physical activity (150 min per week), prolonged sitting (>7 h per day) and minimal sitting (<4 h per day). ANOVA testing was then used to compare passive hip extension between three groups, defined using the specified thresholds: low activity & prolonged sitting, high activity & minimal sitting and high activity & prolonged sitting. RESULTS: A total of 98 participants were allocated to one of the three groups which were shown to differ significantly in passive hip extension (P < 0.001). Importantly, there was 6.1° more passive hip extension in the high activity & minimal sitting group when compared to the low activity & prolonged sitting group. CONCLUSION: This study is the first to demonstrate an association between passive hip extension and prolonged sitting/physical inactivity. It is possible that these findings indicate a physiological adaptation in passive muscle stiffness. Further research is required to understand whether such adaptation may play a role in the aetiology of musculoskeletal pain linked to prolonged sitting.

The Effects of the Barbell Hip Thrust on Post-Activation Performance Enhancement of Change of Direction Speed in College-Aged Men and Women.

This study investigated whether the barbell hip thrust (BHT) enhanced change-of-direction (COD) speed measured by the 505 COD speed test. Forty recreationally trained individuals completed three sessions. Session 1 included one-repetition maximum (1RM) BHT testing to measure absolute and relative strength. Sessions 2 and 3 involved two counter-balanced conditioning activities (CAs): 3 sets × 5 repetitions of the BHT at 85% 1RM and a control condition (CC; 6 min rest). The 505 COD speed test was performed 5 and 2.5 min pre-CA, and 4, 8, 12, and 16 min post-CA in each session. A 2 × 5 repeated-measures ANOVA (p < 0.05) calculated performance changes across time post-CA. A 2 × 2 repeated-measures ANOVA analyzed best potentiated performance. Partial correlations controlling for sex calculated relationships between the 1RM BHT and 505 COD speed test percent potentiation. There was a significant main effect for time (p < 0.001), but not for condition (p = 0.271) or condition × time (p = 0.295). There were no significant correlations between 1RM BHT and potentiation. The 85% 1RM BHT did potentiate the 505 4-16 min post-CA but no more than the CC. Nonetheless, a heavy BHT could be programmed prior to COD drills as COD speed could be potentiated and performance improved in men and women.

Acute Effects of Elastic Bands as Resistance or Assistance on EMG, Kinetics, and Kinematics During Deadlift in Resistance-Trained Men.

The aim of the study was to compare neuromuscular activation, kinetics and kinematics in three variations of the deadlift: (1) free weights, (2) free weights with elastic bands as resistance (bands anchored to the ground) and (3) free weights with elastic bands as assistance (bands attached above the bar). Sixteen resistance-trained men performed one repetition of the three variations as fast as possible using a 2-repetition maximum load in randomized and counterbalanced order. Muscle activation (gluteus maximus, semitendinosus, biceps femoris, erector spinae, vastus lateralis, and vastus medialis), kinematics (average-, peak-, and time to peak velocity), and kinetics (average-, peak,-and time to peak force) were measured during the ascending movement. Resisted and assisted deadlifts led to higher average and peak force outputs (p < 0.001-0.037, ES = 0.29-0.58), and time to peak velocity was shorter when compared to the free weights deadlift (p = 0.005-0.010, ES = 0.83-1.01). However, peak force was achieved faster when using free weights (p < 0.001, ES = 1.58-2.10) and assisted deadlifts had a lower peak velocity compared to resisted and free weights deadlift (p = 0.004-0.046, ES = 0.43-0.60). There were no significant differences in muscle activation between the different conditions (p = 0.082-1.000). In conclusion, the assisted and resisted deadlift produced higher force when compared to free weights. However, free weight and resisted deadlift seem more favorable for the barbell velocity. These findings are of importance for athletes and coaches which should select exercise depending on the goal of the session.

Kinematic differences between successful and faulty spikes in young volleyball players.

This study was designated to investigate the kinematical differences between successful and faulty spikes, in order to identify the best strategies leading to better spike performance. Simulating a real-game condition, 13 elite youth attackers performed 6 spikes in the presence of 2 blocks. The kinematic variables of the spike performances were recorded using 6 optoelectronic cameras (Vicon Motion systems, Oxford, UK). The paired sample t-test was used to compare the kinematic variables recorded during the delivery of successful and faulty spikes. Among the successful trials, both the angular velocities of the knees (≈12.4%) and hips (≈13.3%), and the vertical velocity of the centre of mass at take-off (≈6.5%) and arm swing (≈8.2%) were considerably higher during the plant phase. Consequently, the jump (≈4.3%) and spike (≈1.5%) heights, as well as the wrist velocity (≈5.5%), were significantly higher during the jump phase of successful spikes. In successful spike performances, the attackers adopted higher hip and knee angular velocities, combined with efficient arm swings, to produce higher take-off velocities and reach higher jump heights. This approach provides them with the better position regarding the ball and the blockers to find the best path and hit the ball with higher arm velocities.