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ENERGY COST AND LOWER LIMB BIOMECHANICS OF REPEATED VERTICAL JUMPING AT DIFFERENT CONTACT TIMES
Get PDFThe purpose of the present study was to examine the effects of the contact time on energy cost and lower limb biomechanics during repeated vertical jumping. Nine male Japanese distance runners jumped for three minutes on a force platform for a preferred and long contact time. Sagittal plane kinematics, ground reaction force, and electromyography (EMG) results were measured. The following results were obtained: 1) the energy cost was significantly smaller in the preferred than in long condition, 2) mechanical work of the ankle joint was significantly greater in the preferred than in long condition, 3) mechanical work of the knee joint was significantly greater in the long than in preferred condition. Therefore, a longer contact time alters the distribution of the mechanical work of the ankle and knee joints. This alteration may increase energy cost in the long condition
RELATIONSHIP BETWEEN ANKLE MOBILITY AND GOLF SWING KINEMATICS
Get PDFThe purpose of this study was to examine the relationship between ankle mobility and golf swing kinematics. Sixteen male golfers volunteered to take part. Ankle mobility was assessed using the weight bearing lunge test and three-dimensional kinematic data from 10 golf drives were collected using a Vicon motion capture system. Pearson’s correlation coefficients were calculated to identify the relationship between ankle mobility and the rotations of four segments; pelvis, shoulders, upper arm and forearm. Large positive relationships were identified for the rotations of the pelvis (r = 0.670) and shoulders (r = 0.604) in the downswing as well as for peak rotational velocities of the pelvis (r = 0.553), shoulder (r = 0.571) and upper arm (r = 0.549) segments. These results indicate that improvements in ankle joint mobility are associated with superior rotations of segments further up the kinetic chain and that the weight bearing lunge test should be used as part of golf specific movement screening
THE EFFECT OF CHANGES IN FUNDAMENTAL SKILL COMPLEXITY ON UPPER LIMB LOADING IN FEMALE GYMNASTICS
Get PDFThe aim of this study was to investigate if changes in elbow and wrist joints loading occurred as a function of (a) different hand placement and (b) fundamental skills difficulty level in female gymnastics. Ten female gymnasts performed 54 successful trials of round-off skills (cartwheel [18], round-off [18], round-off to back handspring [18]), with three different hand positions (parallel, T-shape and reverse). Kinematic and kinetic data were collected for each trial. A two-way repeated measures ANOVA was used to analyse the injury risk factors. Results suggested that the T- shape technique during different levels of round-off skills decreases mechanical load (peak vertical ground reaction forces and joint kinetics at the elbow and wrist) and may represent safer technique for young female gymnasts
MEASURING ADDUCTOR MUSCLE ACTIVITY DURING PASSING AND 90°-CUTTING TO INVESTIGATE THEIR ROLE IN THE DEVELOPMENT OF GROIN INJURIES
No full textCutting manoeuvres and inside passing are thought to increase the risk of groin injuries, but research provides only little information in this regard. The purpose of the study was to compare the muscle activation of gracilis and adductor longus during a 90°-cutting manoeuvre and inside passing. Thirteen male soccer players performed the two movements. Muscle activity was measured with surface electromyography. Cutting showed higher maximum activations compared to passing in all investigated muscles. Activation during passing was high when considering that it is a submaximal effort with high amounts of repetition during match and training. Cutting showed the highest adductor activity during movement phases requiring eccentric contraction. Therefore, both movements are likely to put high loads on the adductor muscles and thereby increase the risk of groin injuries
JOINT MOMENTS DURING INSTEP KICKS IN FOOTBALL PLAYERS WITH AND WITHOUT PREVIOUS GROIN PAIN
Get PDFThis study examined how previous groin pain and approach angle affects stance leg and lumbar moments during instep kicks. Male football players with and without previous groin pain (n=11, and n=10) performed instep kicks from 45° and 60° angles while kinetic and kinematic data were recorded (1000Hz and 500Hz respectively). 3D stance leg net joint moments of the hip, knee, and ankle were calculated at peak swing knee flexion and ball contact and the sagittal L5/S1 joint moment was examined throughout the kick. Foot speed at ball contact indicated performance. Players with previous groin pain had lower moments during the kick compared to uninjured controls, but there was no difference in performance. This suggests that the players with previous groin pain utilized an aberrant kicking pattern that offloads certain joints but may cause compensations elsewhere in the kinetic chain
PROXIMAL AND DISTAL CONSTRAINTS REDUCE DIMENSIONALITY OF VERTICAL JUMPING TASKS
Get PDFThe purpose of this study was to examine motor control strategies employed to control the degrees of freedom when performing a lower limb task with constraints applied at the hip, knee and ankle. Thirty-five individuals performed vertical jumping tasks: hip flexed, no knee bend and plantar flexed. Joint moment data from hip, knee and ankle was analysed using principal component analysis (PCA). In all, PCA performed, a minimum of two and maximum of six principal components (PCs) were required to describe the movement. A proximal to distal reduction in variability was only observed for the hip flexed and no knee bend conditions. Collectively, the results suggest a reduction in the dimensionality of the movement occurs, despite the constraints imposed within each condition and would suggest dimensionality reduction and motor control strategies are a function of the task demands
COMPARISON OF PLUG-IN GAIT AND A SIX DEGREES OF FREEDOM MODEL ON ESTIMATING KNEE KINEMATICS DURING A DOUBLE LEG DROP JUMP
Get PDFBiomechanical models allow for a comprehensive understanding of dynamic movements that could be used to assess athletic performance or identify injury risk and return to play status. In order to make clinical recommendations based on these model outputs, discrepancies between modelling approaches need to be identified. The purpose of this study was to compare the knee kinematics between the commonly used Plug-in Gait model and a six degrees of freedom model during the first landing a double leg drop jump (DLDJ). This study identified differences in the model outputs for knee kinematics, most prominently in the frontal and transverse planes. Further investigation is required to determine the reliability and sensitivity of these model outputs
LANDING ASYMMETRY IN BACK TUCKED SALTOS AND THE EFFECT OF TAKEOFF ASYMMETRY
Get PDFLanding asymmetry is an injury risk factor in gymnastics. This study examined whether takeoff force asymmetry is related to landing asymmetry during back tucked saltos in competitive gymnasts. Each gymnast performed an isometric leg strength test followed by multiple back tucked salto trials with no takeoff instruction, leaning with 60% asymmetry to the right, and 60% asymmetry to the left using a standard asymmetry index. Forces were measured at takeoff and landing. The novel experimental approach successfully produced distinct takeoff asymmetry levels. There was a significant rightward asymmetry in baseline landing peak vertical force, possibly due to right leg strength dominance. Landing asymmetry was also generated in the left and right leaning conditions. Both takeoff and leg strength asymmetries may play a role in landing force asymmetries in back tucked saltos
ARCHITECTURAL DIFFERENCES OF LOWER LIMB MUSCLE-TENDON FOR MONOZYGOTIC TWINS WITH DIFFERENT SPORT EXPERIENCES
Get PDFThe purpose of this study was to examine architectural differences of lower limb muscle-tendon for monozygotic twins with different sport experiences and for monozygotic twins with same sport experiences. 50 monozygotic twins (MZT) participated in this study, consisting of 16 MZT with different sport experiences, 34 MZT with same sport experiences. Musculoskeletal ultrasonography is applied to measure the muscle fascicle length of gastrocnemius medialis (GM) muscle as well as Achilles and patella tendon cross-sectional area (CSA) and length. Achilles tendon was separately measured from the AT insertion point on the calcaneus to the distal end of soleus muscle (ATSOL) and to the AT junction between medial and lateral gastrocnemii muscles (ATGML), respectively. The measured intraclass correlation coefficient (ICC) clearly showed poor concordances in the ATSOL length of MZT with different sport experiences (ICC of 0.74), and good concordance in the MG fascicle length of MZT with different sport experiences (ICC of 0.83). Other parameters in all intra-pears showed excellent concordances (ICC\u3e0.9). Thus, different concordances of AT length between GM and SOL parts can indicate the different plasticity by the structural and functional mechanics and different concordances between groups indicate that ATSOL and GM fascicle length are affected not only by genetic factors but also by acquired environmental factors
EFFECT OF FATIGUE ON KNEE KINEMATICS AND KINETICS DURING SIDESTEP CUTTING AND SINGLE LEG LANDING IN FEMALE HANDBALL ATHLETES
Get PDFThe purpose of this study was to investigate the effect of fatigue in knee biomechanics in female handball athletes during the sidestep cutting and single-leg landing. Twenty female handball athletes participated in this study. The fatigue protocol was composed of specific handball movements/actions. The participants performed three trials of the sidestep cutting and single-leg drop landing before (baseline) and after the fatigue protocol. The effect of the fatigue was compared using a paired t-test compared using statistical parametric mapping. During sidestep cutting, the athletes performed the task with lower knee flexion and greater knee abduction during the fatigue state. During the single-leg landing, an increase in the knee valgus was found during the fatigue state. No difference was found on knee kinetics. The fatigue impacted the knee kinematics decreasing the knee flexion during the sidestep cutting and increasing the knee valgus during both, sidestep cutting and single-leg landing tasks