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IMPROVING TUMBLE TURN PERFORMANCE IN SWIMMING – ABOUT THE IMPACT OF WALL CONTACT TIME AND TUCK INDEX
Get PDFRace time can be shortened by improving turn performance in competitive swimming, but this requires insight into the optimal turn technique. This study aimed to experimentally investigate the effect of wall contact time (WCT) and Tuck Index on the tumble turn performance. Eighteen Dutch national level swimmers participated and conducted tumble turns with three different WCTs and Tuck Indices. The results showed that a sufficiently long WCT that allows time to generate a high push-off force at the end of the wall contact when the body is in a proper streamlined position. The results also showed that it is possible to recommend an optimal Tuck Index for individual swimmers, which might help to improve their tumble turn and thus their race performance. These results should be verified by an intervention study in which the swimmers are trained to perform the tumble turn with the recommended WCTs and Tuck Indices
SIMILARITY OF COORDINATION PATTERNS IN A GROUP OF HIGHLY TRAINED SPRINTERS: A NOVEL APPROACH
Get PDFUnderstanding coordination patterns aids technical understanding and potential grouping of athletes that exhibit similar movement patterns. This study assessed between-individual similarity in initial sprint acceleration coordination in highly trained to world class sprinters using a novel pairwise approach. Similarity between participants was higher for thigh-thigh coordination compared to shank-foot and trunk-shank coordination. Mean similarity increased from step 1 to step 4 in shank-foot (0.74 to 0.83) and trunk-shank (0.68 to 0.79) couplings but remained consistent in the thigh-thigh coupling (0.89 to 0.91). Researchers and practitioners should consider that coordination between sprinters converges over initial acceleration, but between any two individuals coordination similarity might increase or decrease across steps
STATURE AND LOAD AFFECT THE WALK TO RUN TRANSITION SPEED
Get PDFMilitary personnel are often required to march “in-step” while carrying heavy loads. For example, the two speeds required to complete the role fitness test for the British Army are close to the preferred walking speed and preferred walk-to-run transition speed (PTS) for healthy adults when unloaded. PTS depends on anthropometry, including stature. Walking at speeds markedly different to PTS has been associated with increased metabolic cost and increased joint loading. There is also limited research into how this PTS is affected by load carriage. To minimise the risk of injury, there is a need to understand how load carriage affects PTS. This study found PTS for male and female personnel decreased with increased load carried, and that female personnel tended to transition from walking to running earlier than male personnel. The relationship between PTS and stature became more positive as load increased, irrespective of sex. Due to the association between deviating from preferred walking gait and increases in joint loading, these findings may have implications for the risk of injury in military personnel who are required to march “in-step”
IMPROVING PELVIC MOVEMENTS DURING DIVING IN FOOTBALL GOALKEEPERS -EFFECTS OF HIP-LOCK TRAINING
Get PDFThe purpose of this study was to introduce Hip Rock to football goalkeepers and to investigate the differences in pelvic movement and lower limb joint torque exertion of the opposite leg before and after Hip Rock Training. All subjects in the training group improved the maximum value of hip extension torque in the opposite leg after training. The effect of the interaction was greater in the training group than in the control group in the demonstration of hip extension torque in the opposite leg. The stability of the pelvic musculature could be obtained, and the extension torque of the hip joint could be improved by gaining a sense of power to the ground. These results suggest that hip lock training and its application training can be useful for goalkeepers who are unable to lower their trunks in the direction of play or move their center of gravity smoothly
FOOTFALL PATTERN IS NOT ASSOCIATED WITH ALTERED ACHILLES TENDON T2* RELAXATION TIME OF RECREATIONAL DISTANCE RUNNERS
Get PDFAchilles tendon (AT) tendinopathy was reported to be the pathology with one of the highest incidences of all running-related injuries. Non-rearfoot FP has been proposed to be the risk factor for AT overload. T2* relaxation time of Achilles tendon is considered to be a marker of AT tendinopathy. Therefore, the purpose of this study was to compare T2* relaxation time of Achilles tendon (AT) between recreational runner population with rearfoot (RF) and non-rearfoot (NR) footfall patterns (FP). Twenty-two middle age recreational runners (11 rearfoot and 11 non-rearfoot), matched according to running distance, participated in this study. Resting T2* relaxation time was determined using a 1.5 Tesla magnetic resonance imaging technique. Lower extremity kinematics and kinetics were recorded during over-ground running at a self-selected speed. No significant differences were found between T2* relaxation time of the insertion portion of the AT between RF and NR runners. Structural properties of the most injured part of the AT is not affected by running FP in healthy middle-aged runners
EARLY PRE-SEASON CHANGES IN THE COUNTERMOVEMENT JUMP OUTCOME AND STRATEGY VARIABLES OF ENGLISH SUPER LEAGUE RUGBY PLAYERS
Get PDFThe aim of this study was to quantify changes in typical (i.e., jump height) and alternative (i.e., jump momentum) countermovement jump (CMJ) outcome and strategy variables, alongside maximal strength, during the early English Super League pre-season period. Twenty professional senior male rugby league players from an English Super League club performed CMJ and isometric mid-thigh pull (IMTP) testing (3 trials of each) on portable dual force plates on the first and last day of pre-season training held prior to a short Christmas break (December 2021). Select CMJ outcome and strategy variables and both absolute and relative (to body mass) peak force for the IMTP trials were automatically calculated via proprietary software. IMTP peak force significantly increased in both absolute and relative terms (moderate effects; g = 0.69) reflecting the aims of the pre-season training programme. Countermovement depth moderately reduced (r = 0.76) but time to take-off and reactive strength index modified remained unchanged. A small but non-significant increase in body mass was noted, which, along with increased jump height (small effect; g = 0.46), contributed to a significant, moderate increase in jump momentum (g = 0.59). Quantifying concomitant changes in CMJ outcome and strategy variables, alongside body mass, during pre-season training may offer richer insight into rugby league players’ future physical development requirements beyond jump height alone
A METHODOLOGICAL APPROACH FOR SIMULATING MUSCULOSKELETAL LOADING IN THE HEAD AND NECK REGION FOLLOWING BOXING PUNCHES TO THE HEAD
Get PDFThe aim of various combat sports is to win the competition by throwing repetitive punches predominantly to the opponent\u27s head. These hitting blows can lead to short and potentially long-term adverse health consequences. The aim of the current study is to introduce an approach that estimates 3D punch forces acting on a struck subject\u27s head. The procedure refers to marker-based kinematic measures and subsequently implementing them into a musculoskeletal head-neck model in OpenSim. The results showed reasonable effective mass estimates, whereby the relatively small force magnitudes and the activation of the reserve moments require methodological modifications followed by the validation of the proposed approach
KEY FACTORS INFLUENCING THE PERFORMANCE OF THE BREAK SHOT IN CUE SPORTS
Get PDFThis study aimed to explore the key factors that could influence the cue tip speed in a break shot in 9-ball. Nineteen male cue sports players at various skill levels were recruited. Each participant performed 8 break shots with maximum effort while the kinematic data were collected for the upper body joints and cue stick using a 3D motion capture system. Multiple linear regression was performed to predict the cue tip speed at impact based on selected kinematic variables of the cue-wielding arm. The results showed that the humeral elevation ROM was the only significant predictor for predicting the cue tip speed at impact (p = 0.007), while the ROM of elbow flexion/extension and wrist abduction/adduction, or peak angular velocities were not significant predictors (all p \u3e 0.05). The cue tip speed decreased as the humeral elevation range of motion (ROM) increased. In conclusion, cue sports players were recommended to limit their humeral elevation ROM in a break shot to maximise cue tip speed for separating the racked object balls
EFFECT OF DOWNHILL RUNNING ON BIOMECHANICAL RISK FACTORS ASSOCIATED WITH ILIOTIBIAL BAND SYNDROME
Get PDFThe purpose of this study was to identify the influence of downhill running on biomechanical risk factors for iliotibial band syndrome. We conducted a 3D motion analysis of 22 females and males running on an instrumented treadmill at four different inclinations (0%, -5%, -10%, -15%) at a speed of 3.5 m/s. We found significant differences for biomechanical risk factors associated with iliotibial band syndrome. Peak knee flexion angle at initial ground contact (p \u3c .001), peak knee adduction angle (p = .005), and iliotibial band strain (p \u3c .001) systematically increased with increasing slope. Downhill running increases biomechanical risk factors for iliotibial band syndrome. Our results highlight the need to consider the individual running environment in assessing overuse injury risk in runners
JUMP-LANDING KINETIC ASYMMETRIES PERSISTED DESPITE SYMMETRIC SQUAT KINETICS IN COLLEGIATE ATHLETES FOLLOWING ACL RECONSTRUCTION
Get PDFAnterior cruciate ligament (ACL) re-injury rates are high in collegiate athletes. Squats and countermovement jumps (CMJ) are commonly used for assessments and training after ACL reconstruction (ACLR). The purpose was to quantify the differences and correlations in kinetic asymmetries between squats and CMJs in collegiate athletes following ACLR. Fourteen athletes performed 1-2 squats and CMJs within 24-month following ACLR for a total of 25 assessments. Greater kinetic asymmetries showed in CMJs than squats. Kinetic asymmetries strongly correlated between the ascending and descending phases in squats and moderately between the jumping and landing phases in CMJs. Two phases of squats moderately correlated with the jumping phase of CMJs but the landing phase. CMJ kinetic asymmetries should be directly assessed and trained for mitigating ACL re-injury risk