GENDER DIFFERENCES OF TRUNK AND LOWER LIMB POSITIONS DURING THE CUTTING MANEUVER

The purpose of this study was to analyze the gender differences in positions of the trunk and lower limb during the cutting maneuver. We captured the trunk and lower limb positions during shuttle-run cutting in 8 male and 7 female soccer players. The distance from the center of the trunk to the foot-plant point in the frontal and sagittal planes, knee flexion angle, knee valgus angle, femoral inclination angle, trunk forward-inclination angle, and trunk lateral-inclination angle were measured. Our results showed that female subjects demonstrated less femoral inclination, greater trunk lateral inclination away from the cutting limb, and smaller distance from the center of the trunk to the foot-plant point in the frontal plane than male subjects. The study results may reveal potential risks for ACL injury

FUNCTIONAL DIFFERENCES IN THE HAMSTRING MUSCLES DURING SPRINTING

The purpose of this study was to demonstrate the respective activation of the biceps femoris (BF), semitendinosus (ST), and semimembranosus (SM) muscles during overground sprinting. Lower extremity kinematics and the electromyographic (EMG) activities of the BF, ST, and SM muscles were recorded for 13 male sprinters performing overground sprinting at maximum effort. Mean normalized EMG activity was calculated in the early stance, late stance, middle swing, and late swing phases. The peak activation time during the stance and latter half of the swing phases was also calculated. Significantly different characteristics for EMG activation and different occurrences of peak activation of the BF, ST, and SM were found within the gait cycle, indicating that the activation demand of each hamstring muscle differs during sprinting

THE KINEMATICS OF OVERGROUND SPRINTING IN TRACK AND FIELD ATHLETES WITH PREVIOUS HAMSTRING INJURIES

The purpose of this study was to examine the kinematic characteristics of lower extremity and long head of the biceps femoris (BFlh) muscle length during overground sprinting in track and field athletes with previous unilateral hamstring strain injuries. Ten male college sprinters with a history of hamstring injury performed a maximum effort sprint on an athletic track. Three-dimensional kinematic data were recorded during sprinting, and the hip and knee joint angles and musculotendon length of the biceps femoris muscle were calculated. The previously injured limb displayed delayed peak hip flexion and increased knee flexion compared with the uninjured limb, placing the BFlh muscle at decreased length during the terminal swing phase of sprinting

RELATIONSHIPS BETWEEN TRUNK AND KNEE ACCELERATION AND THE GROUND REACTION FORCE DURING SINGLE LIMB LANDING

The purpose of this study was to investigate the relationship between the ground reaction force and acceleration of the knee and trunk. We measured trunk and knee acceleration, as well as ground reaction force during single limb landing in 7 female basketball players. The associations between trunk and knee accelerations and vertical ground reaction force were analyzed by using correlation coefficients. Strong correlations were found between peak vertical ground reaction force and peak acceleration of the medial, vertical, and posterior trunk, trunk resultant, vertical knee, as well as knee resultant. It is possible to evaluate the variable movements during sports or sports-related activity by analyzing the acceleration of body segments

Change in muscle thickness under contracting conditions following return to sports after a hamstring muscle strain injury—A pilot study

The purpose of this study was to measure the change in hamstring muscle thickness between contracting and relaxing conditions following a return to sports after a hamstring muscle strain and thereby evaluate muscle function. Six male track and field sprinters participated in this study. All had experienced a prior hamstring strain injury that required a minimum of 2 weeks away from sport participation. Transverse plane scans were performed at the following four points on the affected and unaffected sides under contracting and relaxing conditions: proximal biceps femoris long head, proximal semitendinosus, middle biceps femoris long head, and middle semitendinosus. The results demonstrated an increase in the thickness of the middle biceps femoris long head and middle semitendinosus regions on the unaffected side with contraction, whereas the affected side did not show a significant increase. The proximal semitendinosus muscle thickness was increased with contraction on both the unaffected and the affected sides. By contrast, the proximal biceps femoris muscle thickness did not show a significant increase on both sides. The results of this study show that evaluation of muscle thickness during contraction may be useful for assessing the change in muscle function after a hamstring muscle strain injury

Japanese translation and modification of the Oslo Sports Trauma Research Centre overuse injury questionnaire to evaluate overuse injuries in female college swimmers.

The purpose of the present study was to translate and modify the Oslo Sports Trauma Research Centre (OSTRC) overuse injury questionnaire into Japanese and validate it among Japanese athletes through a longitudinal survey. A modified back-translation method was used to translate the questionnaire from English to Japanese. The longitudinal survey was performed in 29 female college swimmers who were followed up for more than 24 consecutive weeks. The response rate to the 24 weekly questionnaires was 88.8% (95% confidence interval [CI]: 85.2-92.3). Internal consistency was measured by using Cronbach's alpha (0.73 (0.69-0.77)). The anatomical areas most frequently affected by overuse injuries were the lower back (average weekly prevalence: 27.6%, 95% CI: 25.1-30.1), shoulder (16.0%, 95% CI: 13.7-18.2), knee (9.9%, 95% CI: 7.7-12.0), and ankle (9.0%, 7.6-10.5). The severity score showed that knee (22.5, range: 6-65), ankle (21.5, range: 6-67), and lower back (20.7, range: 6-80) injuries had the greatest impact. The Japanese version of the modified OSTRC overuse injury questionnaire demonstrated reliability and validity based on the results of internal consistency and trend of injury of the swimmers. The participants in the present study did not have substantial injuries or time-loss injuries and continued practicing and competing, despite these minor injuries. Although knee and ankle injuries do not occur as often as lower back and shoulder injuries, these injuries often had a greater impact on swimmers when they did occur

Hamstrings biomechanics related to running

Hamstring strain injuries (HSI) occur frequently in sports characterised by high-speed running. Consequently, a thorough understanding of hamstring function during running may help clinicians better understand HSI mechanisms and thus develop better injury prevention and rehabilitative interventions. The purpose of this chapter is to provide an overview of hamstring function during running. The current evidence base suggests that the hamstrings are recruited for the entire stance phase of running, as well as during a portion of the swing phase (from mid-swing onwards). During the late swing phase, the hamstrings undergo active lengthening and experience their greatest lengths. Subsequently, it is likely that this portion of the stride cycle is where the hamstrings are injured. The muscle forces produced by each hamstring muscle during this period are sensitive to the running velocity (i.e. greater running velocities are characterised by greater hamstring muscle forces), whilst the peak length is largely invariant amongst high running velocities (>80% max). Of note to clinicians, hamstring function is likely compromised following HSI; however, more research is needed to identify which specific parameters need the most consideration during rehabilitation. The information in this chapter may inform clinicians when developing HSI preventive and rehabilitative interventions