Non-dominant Leg Research Articles

The effects of two different fatigue protocols on movement quality during anticipated and unanticipated change of directions in female soccer players.

This study compared neuromuscular control under two fatigue protocols during anticipated and unanticipated change of direction (COD) maneuvers and evaluated their effects on the risk of non-contact ACL injuries. Forty-five female soccer players (mean age: 22.22 ± 2.24 years; mean height: 166.24 ± 3.33 cm; mean mass: 59.84 ± 5.03 kg) were divided into three groups: functional fatigue (Soccer specific fatigue ptotocol-SOFT90), non-functional fatigue (Bruce protocol), and control group. Before and after the implementation of neuromuscular control fatigue protocols were evaluated using the cutting motion assessment score tool (CMAS). Two-dimensional (2D) videos were recorded during anticipated and unanticipated COD trials for both dominant and non-dominant legs. Significant time effects (p < 0.05) and group-time interactions (p < 0.05) were observed in both anticipated and unanticipated conditions for both dominant and non-dominant legs after the fatigue protocols. The functional fatigue group exhibited higher CMAS changes, indicating poorer movement quality following fatigue. Notably, the non-dominant leg displayed amplified deficits during unanticipated COD maneuvers following the functional fatigue protocol. Fatigue significantly impairs neuromuscular control, particularly in unanticipated COD situations, which increases the risk of non-contact ACL injuries. To mitigate this risk, coaches, trainers, and medical professionals should prioritize targeted training and injury prevention strategies, focusing on the non-dominant leg during unanticipated COD maneuvers.

Kinematic Differences in the Roundhouse Kick among University Taekwondo Players: Brief Report

This study aimed to investigate the bilateral kinematic differences in temporal variables between the Dominant and Non-dominant legs in the roundhouse kick of college-level women practicing Taekwondo. Four male athletes with black belts volunteered to participate in the study. Participants were instructed to perform five kicks with each leg after visual stimuli at maximal velocity allowing 30-s passive recovery time between each kick. Reaction time, movement time, and attack time in the roundhouse kick were assessed using video cameras and force platforms for both the dominant and non-dominant legs. The analysis revealed no significant differences in reaction times (0.15 ±0.03 and 0.15 ±0.04 s, n=20), movement times (0.62 ±0.06 and 0.64 ±0.04 s, n=20), or attack times (0.77 ±0.09 and 0.79 ±0.06 s, n=20) for the dominant and non-dominant legs (p&gt;0.05). However, a bilateral dominance was observed, consistent with the sporting level of the participants. These results support the training regimen both-guards oriented equally to improve overall performance in Taekwondo.

Effects of kinematics and kinetics parameters of the vertical drop jump test on differences between the sexes and dominant and non-dominant feet

Abstract Study aim: This study clarified the relationship between sex and dominant and non-dominant feet during landing movements in the vertical drop jump (VDJ). Materials and methods: The participants were 16 healthy adults (8 men, 8 women) with no orthopedic history. A three-dimensional motion analyzer and a floor reaction force meter were used for measurement. The exercise task was a VDJ in which the participants jumped from a 30-cm-high platform, and the relationship between sex, dominant leg, and non-dominant leg was compared. Results: In terms of joint angle, the main effect of sex on the internal/external knee joint angle was observed. No significant differences were observed in the other parameters. Conclusions: A sex difference was found in the internal/external angles of the knee joint during the landing of the VDJ from 30 cm. However, there were no differences in the kinematic and kinetic data between the dominant and non-dominant legs.

Postural Sway Characteristics in Static Balance Control of Youth Female Soccer Players

Purpose: Balance control, particularly in uni-lateral domain, is essential in soccer. Majority of the existing studies examined dynamic balance via clinical tools, and primarily involved male players. Thus, the purpose here was to examine the nature of Center of Pressure (COP) postural sway in youth female players across bipedal and unipedal conditions Methods: Sixteen pre-adolescent female competitive players (age 12.4±21.40 years) were asked to stand on a force plate in bi-pedal stance with the dominant and non-dominant legs respectively. Three, 10 second trials were carried out for each condition. Results: As expected, across the four COP measures bi-pedal stance resulted in least sway (P= .05). However, the subsequent analysis showed different center of pressure (COP) profiles in the dominant versus non-dominant condition across COP velocity (P= .003), path length (P= .001) and anterior-posterior (AP) sway (P= .003), with sway area revealing no statistical differences (P= .821). In addition, the analysis of stabilograms confirmed that in the non-dominant condition the pronounced COP oscillations were of lower amplitude and frequency as compared to the dominant leg. Conclusions: Overall, postural asymmetry was found as the sway characteristics on both legs differed, with dominant side exhibiting more sway and faster COP oscillations. In line with the inverted pendulum model, this may be due to less than optimal ability to modulate muscle torques generated at the ankle. It is hypothesized that the postural asymmetry between the dominant and non-dominant legs may result from muscular asymmetries that have been often reported in youth soccer players, as a result of their pronounced foot dominance.

Resistance Training Using VAriable Resistance Suit (VARS) Increased Isometric and Isokinetic Muscle Strength.

While resistance training promotes muscle hypertrophy and strength, accessibility of equipment is a barrier. This study evaluated a wearable VAriable Resistance Suit (VARS) as a novel and alternative method to achieve muscle strength improvement. It was hypothesized that by providing adjustable, bi-directional and speed dependent resistance, VARS can target specific muscles to improve muscle strength via an accessible and portable device. Twelve untrained healthy male adults (22.08 ± 4.1 years old) participated in an 8-week long resistance training using VARS to strengthen four muscles (biceps brachii, triceps brachii, biceps femoris, rectus femoris) of their non-dominant arm and leg using VARS. The results showed significant improvements in the muscle strength measured by isokinetic dynamometer - 49.9±9.6% increase in isokinetic force and 30.6±7.6% increase in isometric force. Muscle size and body composition were also assessed using ultrasound imaging and bioelectrical impedance analysis, which did not show significant changes. The study demonstrates the efficacy and feasibility of VARS as a resistance training tool to achieve muscle strength improvement and its potential extension to clinical populations.

Asymmetries in Postural Stability and Balance Parameters during Specific Elements in Sub-Elite Rhythmic Gymnasts

Purpose: This study aims to investigate the level of lower-limb functional asymmetries in sub-elite rhythmic gymnasts while performing sport-specific elements, including passe and side passe balance stance. Methods: The analysis focuses on postural stability and balance parameters, measured using Gyko, a 3-axis accelerometer, gyroscope, and magnetometer device. The task was to execute a passe balance and maintain the position for 30 seconds, which was the duration of the test, and then perform the same task with the other leg. The test was repeated for both legs in a side passe balance stance. Sixteen active female sub-elite rhythmic gymnasts participated in the study. Results: The results reveal significant differences in the mean travel velocity in all anatomical planes during the passe elements, indicating asymmetry in postural stability in favor of the non-dominant leg (P≤ .01). Similarly, in the side passe balance test, significant differences were observed in the mediolateral (in favor of the dominant leg) and anteroposterior (in favor of the non-dominant leg) total distances, indicating asymmetry in postural stability (P= .03). However, no significant differences were found in other postural stability parameters, the ellipse (EA) and the total length of the trajectory (Len(D)). Conclusions: Evident asymmetries in movement speed during the passe element and imbalances in weight distribution during the side passe balance test do not appear to compromise overall postural stability considering that asymmetry was not proven in several variables, such as the ellipse or the total length of the trajectory. These findings shed light on the potential impact of asymmetries on performance and injury risk in rhythmic gymnastics, emphasizing the importance of considering sport-specific balance tests.

Are physiological, physical, wellness and load decisive markers of starting players? A case study from a professional male soccer team

The study aim was to compare physiological, physical, accumulated wellness and load markers within a European professional soccer team between starters and non-starters. Ten starters (age: 25.1 ± 2.2 years; experience: 7.3 ± 2.3 years) and eight non-starters (age: 26.1 ± 4.6; years’ experience: 8.3 ± 4.1 years) participated in the study. The study was conducted across 20 weeks where 75 training sessions and 15 matches occurred. Wellness (fatigue, quality of sleep, muscle soreness, stress and mood) and load (rating of perceived exertion (RPE), accelerations, decelerations, high-speed running and sprinting) measures were observed. Physiological evaluation consisted of a 1200 m maximum effort shuttle test while physical capacity assessment included isokinetic strength, jump ability and balance tests. Isokinetic tests were used to assess peak torque of both legs (extension and flexion at 60◦/s and 180◦/s), single squat jump and single hop jump were utilized to assess jump ability and Y-balance tests were employed to examine balance. Starters presented significantly higher values for peak torque extension of the non-dominant leg compared to non-starters (p = 0.038, effect size (ES) = 0.996), while non-starters showed higher values for both Y-balance postero-medial and postero-lateral (p = 0.009, ES = −1.309 and p = 0.021, ES = −1.133, respectively). Accumulated duration and RPE were lower for non-starters than starters (p ≤ 0.001, ES = 1.268, and p = 0.022, ES = 1.123, respectively). The physiological and physical tests conducted in this study do not seem to determine the starting status of players, considering that only one test revealed significantly higher values for starters. Despite the lower training and match duration for non-starters, this showed that it is possible to accumulate identical load while managing wellness regardless of starting status.

Age, Sex, and Training Specific Effects on Cross-Education Training.

An extensive number of publications have examined cross-education effects with adults, primarily investigating contralateral homologous (same) muscles. There are far fewer investigations on cross-education effects on contralateral heterologous (different) muscles and age (youth vs adult) and no studies investigating sex differences. Hence, the objective was to compare cross-education in female and male youth and young adults to contralateral homologous (chest press [CP], elbow flexors and extensors, handgrip isometric strength, and shot put) and heterologous (leg press, knee extension isometric strength, and countermovement jump) muscles. Twenty-eight female adults, 28 female youth, 28 male adults, and 28 male youth (total: 112) were examined before and after an 8-week (3 sessions/wk) unilateral, dominant arm, CP training program. Unilateral testing assessed dominant and nondominant leg press and CP 1-repetition maximum, knee extensors, elbow extensors, elbow flexors, and handgrip maximum voluntary isometric contraction (MVIC) strength, as well as shot put distance and countermovement jump height. Unilateral CP training induced training specific (CP 1-repetition maximum) and nonspecific (elbow extensors, elbow flexors, handgrip MVIC force, and shot put distance) improvements (P < .04, η2: .45-.85) but no significant lower body improvements. There was evidence for testing limb specificity as the dominant arm provided significantly (P < .021, η2: .17-.75) greater training gains than the nondominant arm. Youth's training adaptations exceeded with unilateral CP 1-repetition maximum, elbow extensors MVIC force, and shot put distance (P < .049, η2: .14-.49). No sex main effect differences were apparent. In conclusion, cross-education was training specific (greatest gains with upper body and dominant limbs) with greater benefits for youth and generally no sex differences with the exception of elbow extensors MVIC.

Acute effects of repeated isoinertial lunges on jump and sprint parameters

Background and Study Aim. Understanding the relationship between repeated isoinertial lunges and jump and sprint parameters is an important factor in achieving success in sports requiring explosive strength and speed. The aim of this study was to examine the acute effects of repeated isoinertial lunges on jump and sprint parameters. Material and Methods. Volunteered 42 students from Sports Sciences Faculty were participated to the study. They were randomly divided into experimental group (EG) (n=22, age=22.8±1.1year, height=180.6±7.1cm, body weight=77.5±8.8kg) and control group (CG) (n=20, age=23.0±2.1year, height=173.1±5.6 cm, body weight=71.3±8.4 kg). As pre- and post-tests, each participant performed squat jump (SJ), countermovement jump (CMJ), and 30m sprint on a non-motorized treadmill. Isoinertial lunges were included in 8 reps with dominant leg (DL), 1 min rest, and 8 reps with non-dominant leg (NDL). As a statistical analysis, pre- and post-test differences were analyzed with independent t test between groups and paired t test within groups. The level of significance was taken as p≤0.05. Results. There were pre-test and also post-test differences between groups in SJ (p&lt;0.05) but there were no differences within groups. Both groups had significant pre- and post-test time, velocity, and power differences [for EG: p&lt;0.01, p&lt;0.001, p&lt;0.01; for CG: p&lt;0.001, p&lt;0.001, p&lt;0.01, respectively]. EG had significant pre- and post-test differences in stride frequency (SF) (p&lt;0.01). There was a post-test SF difference between two groups (p&lt;0.05). There were no statistically significant pre-test differences between the groups in 30m sprint parameters of NDL and DL. There were only significant post-test differences between the groups in SFDL (p&lt;0.005) and NDL horizontal force (HFNDL) (p&lt;0.01). EG had only significant pre- and post-test differences in SFDL and PNDL (p&lt;0.005 and p&lt;0.05). Conclusions. Detailed studies in SF and SFDL increases result by repeated isoinertial lunges should be beneficial focus on DL neuromuscular activation. Furthermore, incorporating repeated isoinertial lunges into training regimens could be a valuable strategy for enhancing specific aspects of athletic performance in sports that demand high levels of speed and explosive power.

EFFECT OF STRENGTH TRAINING ON STATIC BALANCE IN BASEBALL ATHLETES

The purpose of this study was to investigate the effect of strength on the static balance of Pakistani baseball athletes. This study shows how elite Pakistani baseball players' static balance may improve following a 12-week strength training pre/post-intervention. The participants were separated into two groups of ten: the experimental group and the control group. The experimental group completed 12 weeks of strength training, whereas the control group received no treatment. The Romberg test was used to measure the participants' static balance in four different positions: standing on both feet with eyes open, standing on both feet with eyes closed, standing on the dominant leg with eyes closed, and standing on the nondominant leg with eyes closed. The experimental group's static balance improved significantly following the 12-week strength training intervention. The study's findings demonstrated that 12 weeks of strength training significantly improved Pakistani baseball players' static balance. Furthermore, the strength training program had a substantial and good impact on the static balance of Pakistani baseball players. It is suggested that the Pakistan Baseball Federation implement strength training and focus on improving static balance in order to improve various aspects of Pakistani baseball players' performance.

The Relationship Between Hamstring Shortness and Postural Control in Football Players: A Pilot Study

Hamstring muscles significantly contribute to lower limb mobility and overall body balance. Specifically, hamstring muscle tightness has been suggested as a potential factor affecting an athlete’s postural control. Therefore, this study aims to contribute to the ongoing discourse by investigating the possible relationship between hamstring muscle tightness and postural control among football players. Sixteen male football players (mean age: 20.19 ± 2.17 years, body mass index: 22.01 ± 1.82 kg/m2) with hamstring muscle tightness participated in this cross-sectional study. The assessment of hamstring muscle tightness was conducted through the Active Knee Extension Test. Additionally, the participants’ postural control was evaluated using the Biodex Balance System. The correlation between Active Knee Extension Angle and Postural Control was analyzed through Spearman correlation test. No significant relationship was found between the active knee extension angles of both dominant and non-dominant legs and the postural control measurements (p &amp;gt; 0.05). The study revealed a lack of correlation between active knee extension angle and postural control among football players with hamstring muscle tightness. These findings indicate that hamstring muscle tightness may not impact postural control. Furthermore, it is observed that research involving broader and more diverse participant groups is needed to comprehensively understand this relationship.

Impact of Starting Knee Flexion Angle on Muscle Activity and Performance during Plyometrics without Jumping.

Most of the existing research has focused on jump plyometrics, where landing reaction forces must be dissipated among lower limb articulations. In contrast, the investigation of resisted plyometrics without jumping, devoid of such landing forces, remains relatively limited. This study aimed to (i) investigate the impact of resisted plyometrics without jumping at two knee flexion angles (60 and 90 degrees) on vastus muscle activity relative to limb dominance and (ii) assess strength, power, and work during the concentric-eccentric phases of these exercises. Thirty-one healthy participants underwent quantification of lower limb muscle amplitude, strength, power, and work during resisted plyometrics without jumping from both 60° and 90° knee flexion positions. After anthropometric evaluations, participants used a dynamometer with a load equal to 80% of body weight while wireless surface electromyography electrodes recorded data. Statistical analyses utilized paired t-tests or nonparametric equivalents and set significance at p ≤ 0.05. Results showed significantly higher muscle activity in the vastus medialis (VM) (dominant: 47.4%, p = 0.0008, rs = 0.90; nondominant: 54.8%, p = 0.047, rs = 0.88) and vastus lateralis (VL) (dominant: 46.9%, p = 0.0004, rs = 0.86; nondominant: 48.1%, p = 0.021, rs = 0.67) muscles when exercises started at 90° knee flexion, regardless of limb dominance. Substantial intermuscle differences occurred at both 60° (50.4%, p = 0.003, rs = 0.56) and 90° (54.8%, p = 0.005, rs = 0.62) knee flexion, favoring VM in the nondominant leg. Concentric and eccentric strength, power, and work metrics significantly increased when initiating exercises from a 90° position. In conclusion, commencing resisted plyometrics without jumping at a 90° knee flexion position increases VM and VL muscle activity, regardless of limb dominance. Furthermore, it enhances strength, power, and work, emphasizing the importance of knee flexion position customization for optimizing muscle engagement and functional performance.

Bilateral Deficits in Dynamic Postural Stability in Females Persist Years after Unilateral ACL Injury and Are Modulated by the Match between Injury Side and Leg Dominance.

Previous research has documented brain plasticity after an anterior cruciate ligament (ACL) tear and suggests that these neural adaptations contribute to poorer motor control. Since both brain hemispheres show adaptations, we hypothesized that reduced dynamic stability occurs not only in the injured, but also the contralateral, uninjured leg. Further, given brain hemispheric specialization's impact on motor coordination, we hypothesized the need to consider the injury side. A total of 41 female athletes and 18 controls performed single-leg jump-landings. Dynamic postural stability was measured as time-to-stabilization (TTS). We found reduced medio-lateral dynamic stability for the ACL injured leg (p = 0.006) with a similar trend for the contralateral leg (p = 0.050) compared to the control group. However, when distinguishing between injuries to the dominant and non-dominant legs, we found increased medio-lateral TTS only if the injury had occurred on the dominant side where landings on injured (p = 0.006) and contralateral (p = 0.036) legs required increased TTS. Assessments of dynamic stability, e.g., in the context of return-to-sport, should consider the injury side and compare results not only between the injured and the contralateral leg, but also to uninjured controls. Future research should not pool data from the dominant-leg ACL with non-dominant-leg ACL injuries when assessing post-injury motor performance.

Unilateral and Bilateral Isokinetic Leg Extensions Exhibit No Differences in Neuromuscular Excitation Under Maximal and Fatiguing Conditions.

Abstract Anders, JPV, Neltner, TJ, Smith, RW, Arnett, JE, Housh, TJ, Schmidt, RJ, and Johnson, GO. Unilateral and bilateral isokinetic leg extensions exhibit no differences in neuromuscular activation under maximal and fatiguing conditions. J Strength Cond Res 38(3): 474–480, 2024—The bilateral deficit is a phenomenon where force production during a bilateral (BL) muscle action is less than the sum of force produced when the muscle action is performed unilaterally (UL) with both limbs. The purpose of this study was to compare peak force, electromyographic (EMG) amplitude (AMP), and mean power frequency (MPF) of the nondominant leg between UL and BL isokinetic leg extensions. Eleven recreationally trained men (mean ± SD; age = 20.8 ± 1.7 years; body mass = 84.0 ± 16.2 kg; height = 179.3 ± 7.2 cm) volunteered to participate in this study. The 2 test visits included UL and BL maximal isokinetic leg extensions at 180°·second−1 followed by a fatiguing task of either 50 UL or 25 UL followed immediately by 25 BL (ULBL) maximal, isokinetic leg extensions at 180°·second−1, in random order on separate days. The results demonstrated a significant (p = 0.015, = 0.460) bilateral deficit in force (UL = 56.29 ± 11.20 kg; BL = 50.32 ± 7.35 kg; d = 0.63; 95% CI [1.42, 10.52]) but no significant bilateral deficit in EMG AMP (p = 0.892, = 0.002). The peak force during the fatiguing task demonstrated a significant main effect for repetition (p &lt; 0.001, = 0.943) characterized by a reduced peak force from repetitions 20–50. Similarly, EMG MPF demonstrated a significant main effect for repetition (p &lt; 0.001, = 0.702) characterized by a reduced EMG MPF from repetitions 35–50. There were no significant effects (p = 0.102–0.387, = 0.096–0.203) for EMG AMP. These findings suggested that the bilateral deficit was not associated with a neuromuscular deficit and UL muscle actions may be used to potentiate force production of subsequent BL muscle actions.

Test-Retest Reliability and Convergent Validity of Piezoelectric Force Plate Measures of Single-Leg Sit-to-Stand Performance in Trained Adults.

Makaracı, Y, Nas, K, Ruiz-Cárdenas, JD, Gündüz, K, Aydemir, M, and Orange, ST. Test-retest reliability and convergent validity of piezoelectric force plate measures of single-leg sit-to-stand performance in trained adults. J Strength Cond Res 37(12): 2373-2380, 2023-The single-leg sit-to-stand (STS) test has emerged as a promising method of assessing lower-limb functional strength and asymmetry. However, the reliability of its performance parameters on a force plate has not been explored. This study examined the test-retest reliability and convergent validity of the single-leg STS test performed on a piezoelectric-based force plate in trained subjects. Thirty trained male adults (age: 21.4 ± 1.7 years) performed 3 separate single-leg STS days of testing to assess both intraday and interday reliability. Performance parameters included STS time, ground reaction force (GRF), and center of pressure (CoP) sway velocity. The relationship between single-leg STS parameters and unilateral countermovement jump (CMJ) variables was assessed for convergent validity. Intraclass correlation coefficient (ICC) and coefficient of variation (CV) were calculated for reliability analyses, and convergent validity was assessed with Spearman's correlation coefficient (ρ). In the dominant leg, single-leg performance parameters showed moderate-to-excellent intraday reliability (ICC = 0.65-0.90, CV = 4.3-11.2%) and moderate interday reliability (ICC = 0.54-0.74, CV = 5.8-13.5%). In the nondominant leg, all single-leg STS performance parameters showed good intraday (ICC = 0.79-0.86, CV = 3.8-9.8%) and interday reliability (ICC = 0.75-0.82, CV = 4.6-9.7%). STS times in the dominant and nondominant legs were inversely related to unilateral CMJ velocity (ρ = -0.47 and -0.38, respectively). CoP sway velocity in the nondominant leg showed positive correlations with unilateral CMJ power and velocity (ρ = 0.38 and 0.54, respectively). In conclusion, the force plate-based single-leg STS test provides reliable measures of STS time, GRF, and CoP sway velocity in trained adults and could be used to assess lower-limb function and asymmetry.

The Effect of a Balance Training Program on the Balance and Technical Skills of Adolescent Soccer Players.

Soccer is a complex sport, and balance appears to play a crucial role in the quality execution of technical skills, which are mostly performed while standing on one foot. Nevertheless, in younger ages, when learning still affects soccer performance, the effect of a balance-training program on the player's balance and technical skills remains unexplored. This research examined the effect of a balance-training program (BTP) on balance and technical skills of adolescent soccer players. Τhe participating volunteers were thirty-two soccer players (12-13 years old with 3.84 ± 0.95 years of practice), randomly separated into two groups: an experimental (EXP, n1 = 17) and a control group (CON, n2 = 15). Both groups were evaluated in static and dynamic balance and in technical skills (dribbling, passing, juggling, and shooting with dominant and non-dominant legs) before (Pre-condition) and after the intervention (Post-condition) which was an eight-week BTP for the EXP group and a placebo-training program for the CON group. Α 2 by 2 (groups×condition) mixed analysis of variance (ANOVA) with repeated measures on the condition factor was used to assess possible differences between groups. A significant groups × condition interaction effect was found in dynamic balance (p = 0.008), static (p = 0.042), and shooting (p = 0.022) with dominant leg performance. The EXP group improved (p = 0.007) its static balance by 37.82% and also significantly improved its dynamic balance and shooting accuracy with dominant leg in Post condition by 24.98% (p = 0.006) and 83.84% (p = 0.006) respectively. No significant improvement of other variables was detected in the EXP group Post condition. Dynamic and static balance, and shooting with dominant leg skills can be improved in adolescent soccer players through a specialized 8-week BTP. Balance-training program may contribute to technical skill improvement in soccer training.

Assessing Limb Dominance and Interlimb Asymmetries Over Multiple Angles During Change of Direction Speed Tests in Basketball Players.

Gonzalo-Skok, O, Dos' Santos, T, and Bishop, C. Assessing limb dominance and interlimb asymmetries over multiple angles during change of direction speed tests in basketball players. J Strength Cond Res 37(12): 2423-2430, 2023-The aims of this study were to establish whether directional dominance is displayed during change of direction (COD) tasks across various angles, to determine the angle-variation data for the asymmetry magnitude and direction, and to analyze the relationships in COD performance (completion time and COD deficit) across tasks. Twenty-four young (U-16 to U-20), highly trained male basketball players performed a 10-m linear sprint test and four 10-m COD tests (45°, 90°, 135°, and 180°) in left and right directions. Change of direction performance was determined via total times and COD deficit, and asymmetry comparisons were made between faster and slower directions and dominant leg (DL) (i.e., first step leg in lay-up) and nondominant leg (NDL). No significant differences (p > 0.05) were found between DL and NDL for any task excluding 45° COD (p < 0.05, effect size [ES] = 0.44-0.78), but significant differences were established between faster and slower sides for all angles (p < 0.05, ES = 0.70-1.28). Levels of the agreement in directional dominance during COD tasks were generally poor to slight (k = -0.14 to 0.14), excluding a fair agreement between COD45 and COD90 (k = 0.34). Correlations between COD total times and COD deficits between angles were moderate to very large (r = 0.32 to 0.81) and moderate to large (r = -0.30 to 0.55), respectively. Players displayed superior COD performance in a particular direction across various angles. This directional dominance is not necessarily consistent between angles, thus highlighting the angle-dependent nature of COD performance. Consequently, practitioners should investigate multiple angles and directions to create a COD angle profile for their athletes.

Rehabilitation of Gate and Balance Disorders in Multiple Sclerosis using Progressive Resistance Power Training: a Randomized Controlled Study

INTRODUCTION. Progressive resistance training (PRT) has been recognized as an effective tool in the rehabilitation of patients with multiple sclerosis (MS), however its comparative efficacy remains has yet to be determined.&#x0D; AIM. In this study, we aimed to evaluate the efficacy and safety of the self-guided in-patient progressive resistance power training (PRT) program for improving gait and balance in patients with MS compared with the standard rehabilitation program.&#x0D; MATERIALS AND METHODS. 60 patients with MS were equally randomized into control group (CG) and the PRT group (PG). Training was performed 5 times/week, for 4 weeks in both groups. The primary endpoint was the percentage of patients with improvement in the 6-minute walking test above a minimal clinically significant difference in both groups. Tests of walking speed and balance (Timed 25-foot walking test (T25FW), Timed up-and-go (TUG) test, walking speed), mean voluntary muscle contraction on dominant and non-dominant legs as well as quality of life tests (cognitive and physical domains) at week 4 were used as secondary endpoints.&#x0D; RESULTS. In PG, 17/27 (63 %) patients reached the primary endpoint compared to 11/23 (48 %) in KG, which did not make a statistically significant difference (p = 0.89). Patients showed significant improvement in the T25FW test and TUG test in PG, but not in CG one. Muscle strength improved in both groups, however patients in PG showed mostly improvement in non-dominant leg and more on knee flexors and feet extensors, while patients in the CG showed improvement in hip flexors on both legs. Quality of life parameters improved in both groups. There were no statistically significant differences between the groups at all the endpoints studied at week 4.&#x0D; DISCUSSION. In both groups, significant increases in distance and walking speed prevented reaching the primary endpoint. PRT has been shown to provide a statistically significant improvement in short-distance walking speed, which may have been due to a positive effect on the rate of force development, increasing walking speed and improving walking balance. The increase in muscle strength occurred in trained muscle groups and had differences between the study groups. This result could be obtained both due to the direct training of certain muscle groups, and due to the phenomenon of contralateral transfer.&#x0D; CONCLUSION. Progressive resistance training may have some beneficial differences compared to non-progressive training that need to be elucidated further.

The Significance of Maximal Squat Strength for Neuromuscular Knee Control in Elite Handball Players: A Cross-Sectional Study.

Both weak muscle strength and impaired neuromuscular control has previous been suggested as risk factors for future traumatic knee injury. However, data on the relationship between these two factors are scarce. Thus, the aim of this study was to investigate the relationship and influence of the one repetition maximum (1RM) barbell squat strength on dynamic knee valgus in elite female and male handball players. In this cross-sectional study 22 elite handball players (7 females) were included. A unilateral drop jump (VDJ) test was used for the assessment of frontal plane dynamic knee valgus. Players also performed a one repetition maximum (1RM) barbell squat test, expressed relative to bodyweight (r1RM), to assess maximal strength, which were dichotomized to analyze 'weak' versus 'strong' players according to median. Correlations were noted between r1RM in squat and knee valgus angle for both the non-dominant (r = -0.54; p = 0.009) and dominant leg (r = -0.46, p = 0.03). The odds of knee valgus were eight times higher, for the dominant leg, in the weak group compared to the strong group (p = 0.03) and 27 times higher, for the non-dominant leg (p = 0.002). The outcome of the present study suggests that maximum squat strength plays an important role when it comes to neuromuscular control of the knee, and that weak handball players are at higher risk of knee valgus compared to strong players during jumping activity.

Relationship between tendon elastography and clinical and ultrasound enthesitis scores in patients with psoriasis or psoriatic arthritis

Aim: To determine the existence of a correlation between the elastographic study of the patellar and Achilles tendons and the enthesis evaluation in patients with psoriasis with or without psoriatic arthritis. Methods: Observational, cross-sectional study. Patients with psoriasis, psoriatic arthritis and healthy controls were included. The elastography results of the patellar and Achilles tendons of the non-dominant leg of the three groups were compared and tested for correlation with the Madrid Sonographic Enthesis Index (MASEI) score, as well as an entheses clinical evaluation score [Spondyloarthritis Research Consortium of Canada (SPARCC)]. Results: Forty-eight patients were included, 24 with psoriasis and 24 with psoriatic arthritis, as well as 48 healthy controls. Patients with psoriatic arthritis had a higher clinical enthesitis score than patients with psoriasis (8.0 vs. 1.0, P &lt; 0.001). The mean (standard deviation) or median (25–75 percentile) of control subjects patellar and Achilles’ tendon stiffness, 127.8 kPa (18.5 kPa) and 198.0 kPa (183.2–212.0 kPa) were significantly higher than observed in patients with psoriatic arthritis, 119.2 kPa (19.7 kPa) and 184.8 kPa (175.5–193.9 kPa; P &lt; 0.001 and P = 0.018, respectively). A strong inverse correlation between MASEI score and the patellar and Achilles’ tendon stiffness was also detected (Spearman’s Rho coefficient of –0.813 and –0.941, respectively). Conclusions: Patients with psoriatic arthritis present less stiffness in those load-bearing tendons than healthy controls. There is an inverse correlation between the enthesis involvement demonstrated by ultrasound and the elastography of these tendons. Tendon elastography can be considered a useful quantitative tool in assessing patients with psoriatic disease.