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COMPARING POSTURAL CONTROL IN ADOLESCENTS (11-14 YEARS) INVOLVED/NOT INVOLVED IN AFTERSCHOOL SPORTS ACTIVITIES: A PILOT STUDY
Full text linkThis study characterized postural control (PC) of adolescents who were involved (A=athletes) or not involved (NA=non-athletes) in after-school sport activities. PC was determined by the median velocity (MVelocity, mm/sec) of the center-of-pressure (COP) on a force plate when removing vision (eyes closed) and manipulating somatosensation (standing on firm or foam surface) while in two-foot, tandem, and one-foot stances (12 stances). Fifty-one youth, 22 A (age 12.1±0.9 yrs, 10 females) and 29 NA (age 12.3±0.7 yrs, 10 females) performed two, 30-sec trials in all 12 stances, with the best trial used for data analysis. The Mann-Whitney test revealed lower MVelocity (i.e., less sway) in the COP in all 12 stances for the A group: however, significant differences were seen in only two stances: Tandem eyes open on firm and foam
LATERAL STEP-DOWN IS MORE SENSITIVE TO LOWER LIMB MISALIGNMENT IN PATIENTS WITH PREPATELLAR PAIN THAN FORWARD STEP-DOWN
Full text linkThe aim of this study was to determine whether forward or lateral step-down tasks were more sensitive in detecting lower limb misalignment in individuals with patellofemoral pain syndrome (PFPS). The PFPS group (n=26) and the healthy controls group (HC) (n=20) performed the forward step-down (FSD) and the lateral step-down (LSD). Lower extremity kinematic metrics were captured by an 8-camera motion capture system. A two-way ANOVA assessed the effect of group and sex on these metrics. Results revealed that in FSD, there was only a main effect of sex. In LSD, PFPS showed greater peak hip adduction angle (p = 0.04), peak hip internal rotation angle (p = 0.01) and peak pelvic angular velocity. The lateral step-down task emerged as a more sensitive tool for quantitatively evaluating abnormal dynamic lower limb force lines in PFPS
THE INFLUENCE OF STATURE ON HUMAN VERTICAL JUMPING PERFORMANCE
Full text linkHumans become relatively weaker as they increase in size. Despite this, simulations have shown that increased size is of benefit in vertical jumping when isometric scaling is employed due to beneficial effects on the shortening velocity of muscles. Human body mass scales allometrically with the square of stature and it is shown that, assuming constant body composition, strength scales as a function of stature and independently of width and depth. A four-segment planar torque-driven computer model was used to simulate squat jump performance. Body dimensions were scaled allometrically to stature ±3 standard deviations from the mean stature of a young European male (178.8 cm ± 7.22 cm). An increase in stature of 43.4 cm led to a 5.8 cm improvement in flight height, but a reduction in the relative peak power and average vertical acceleration of the mass centre. Increased stature may therefore be of benefit in developing high centre of mass velocities, but a disadvantage in acceleration
THE INFLUENCE OF LOWER LIMB MUSCLE PRE-ACTIVATION ON KNEE JOINT DYNAMIC CONTROL DURING A SINGLE-LEG LANDING TASK IN BADMINTON
Full text linkPurpose: Lower limb neuromuscular strategies impact knee biomechanics, crucial for ACL injury prevention. Yet, the link between them remains unclear. In our randomized trial with 34 badminton players, we examined lower limb muscle preactivity during single-leg landings. Findings revealed that increased rectus femoris preactivation correlated with heightened knee valgus angle. Moreover, higher lateral hamstring/quadriceps co-contraction ratios predicted increased knee extension moments. These outcomes suggest potential benefits in ACL injury prevention through reduced quadriceps pre-activation and optimal lateral hamstring/quadriceps co-contraction ratios. Understanding these relationships aids in developing targeted prevention strategies for anterior cruciate knee injuries
ESTIMATING JOINT MOMENTS DURING TREADMILL RUNNING USING VARIOUS CONSUMER BASED WEARABLE SENSOR LOCATIONS
Full text linkWe estimated lower limb sagittal plane joint moments during treadmill running using wearable sensors and different commonly used locations. We compared outcomes from supervised recurrent neural network machine learning (ML) models to criterion values from motion capture and inverse dynamics. The normalised root mean squared error between outcomes from the ML model fed with the entire wearable dataset (pressure insoles and inertial measurement units at the foot, wrist, T10, and sacrum) was 8.9%, 13.5%, and 18.2% for the ankle, knee, and hip joint respectively. Removal of any two upper body sensors did not decrease the accuracy of the estimations. This work is a springboard to providing biomechanical feedback to runners to help improve performance and minimise injury risk
EFFECT OF FATIGUE ON TRUNK- AND HIP-KNEE COORDINATION DURING SIDESTEP CUTTING MANEUVER IN HANDBALL ATHLETES
Full text linkThis study investigated how fatigue impacts trunk-hip and hip-knee coordination in female handball athletes during the sidestep cutting maneuver (SCM). Twenty participants performed three trials of the SCM task under pre- and post-fatigue conditions. An eight-camera motion capture system tracked reflective markers attached to their skin to compute the trunk, hip, and knee angles. A vector coding technique evaluated coordination patterns. Results indicated that while trunk-knee coordination remained unaffected by fatigue, significant changes were observed in the hip-knee coordination within the transversal plane post-fatigue. These findings highlight the need for customized training that considers possible joint changes caused by fatigue
IMPACT OF FOREFOOT CUSHIONING STIFFNESS ON BLOCK START PERFORMANCE IN SPRINTING
Full text linkThis study aimed to identify the impact of different forefoot cushioning properties in “advanced spiked footwear” on sprinting performance during the block start. Kinetic parameters were collected for twenty-three competitive sprinters during a block sprint start in two advanced spike conditions with only a difference in forefoot cushioning stiffness. An instrumented start block was used to measure the ground reaction forces applied in the front and rear leg. The stiffer shoe condition showed significantly better performance for most parameters, suggesting a softer midsole in forefoot cushioning is not related to better block start performance. This study has demonstrated that differences in midsole materials can alter sprinting block performance and should be considered when analysing advanced spikes features, especially across different shoe brands and their cushioning technologies
PELVIC LIST STRENGTH AS AN INDICATOR OF SPRINT PERFORMANCE
Full text linkThis study aimed to develop a new test for evaluating pelvic list strength and to clarify whether the test would be an indicator of sprint performance. The new pelvic list strength test evaluated the vertical ground reaction force produced by maximal pelvic list using a force plate which was set underneath the supporting foot. For the experiment, 14 male sprinters performed 60-m sprint and the pelvic list strength test. The pelvic list strength test values were 6.05 ± 1.36 [N/kg] and 6.07 ± 1.02 [N/kg] for the right and left sides, respectively. Significant correlations were found between the right pelvic list strength and 60-m and 30 to 60-m sprint times (no significant correlation being found for the left side). The results demonstrate that the developed new test could be an indicator of the sprint performance especially during the later acceleration section
THE EFFECT OF INCREASING ISOMETRIC STRENGTH ON TECHNIQUE DURING THE FRONT FOOT CONTACT PHASE IN ELITE CRICKET FAST BOWLERS
Full text linkThe study investigates the effect of increased isometric strength on technique in elite male cricket fast bowlers. A 16-segment forward-dynamics simulation model individualised to investigate optimal technique of the front foot contact phase of fast bowling for ten elite male bowlers was utilised. For each individualised model, isometric strength was increased by 5%, technique (initial body configuration and subsequent movement) re-optimised, and the differences between the original and strengthened optimal techniques analysed. Ball release speed increased by-1) with a delay in bowling arm circumduction the only technique difference observed. No differences were found when comparing kinetic parameters. This suggests isometric strength does not limit technique in elite bowlers, this knowledge could influence elite coach development and applied practice
ASSOCIATION BETWEEN BIOMECHANICAL CRITICAL SPEED AND THE SPEED AT ANAEROBIC THRESHOLD
Full text linkThis study investigated the associations between the running speeds corresponding to deflection points in biomechanical parameters and the speed at the anaerobic threshold. Fifteen male recreational runners participated, running on a treadmill with gradual speed increases until perceived exhaustion. The anaerobic threshold was measured using a spiroergometry device, and kinematic data were recorded by four inertial sensors on their shanks and trunk. Stepwise regression analysis indicated that the running speeds at the deflection points of angular velocity of thorax rotation and peak tibial acceleration were the most effective predictors of the speed at the anaerobic threshold (adjusted R2 = 0.65). The running speed at a kinematic deflection point proves to be an effective predictor of anaerobic threshold speed, providing a valuable tool for tailoring training intensities