This study identifies the optimal crouched starting positions (elongated, medium, or bunched) from push-off to the first two steps. Seven elite sprinters were recruited as participants in this study (aged: 21[Formula: see text][Formula: see text][Formula: see text]2 years). A high-speed camera (250[Formula: see text]Hz) was used to collect motion-based images on a sagittal plane. Kwon3D (software) was used to analyze the center of mass (COM) movement, step length, foot linear velocity, take-off angle, and trunk angle. Participants were tested in a 60[Formula: see text]m sprint for bunched, medium, and elongated starting positions. A one-way analysis of variance (ANOVA) ([Formula: see text]) with repeated measures was performed to determine the difference in kinematics in the three crouched starting positions. The LSD comparison was applied to examine differences among pairs of means. Our results indicated that the medium starting position demonstrated a greater first step length and foot linear velocity when compared to the bunched starting position. In the first step toe-off, a lower COM vertical velocity was observed in the medium starting position when compared with the elongated starting position. This study concluded that the medium starting position was the ideal starting position.
Introduction:The aim of this study was to explore effects of fatigue in lower back muscles on the performance of countermovement jumps (CMJ), jump shots (JS) and landing impact.Methods: Twelve male healthy collegiate basketball players (age: 22.8 ± 2.7 yrs, stature: 178.0 ± 5.1 cm, body mass: 74.5 ± 6.8 kg) volunteered to participate in this study. Data were collected utilizing a 3D motion analysis system, force plate, and surface electromyography. Field-goal percentage, the lowest point of the center of mass (CoM), the angles of joints during taking off phase and landing, and the electromyography parameters of the rectus femoris, erector spinae lumbalis, and of the lower limbs when performing CMJ and JS were recorded. Lower back muscle fatigue intervention was introduced and followed by a post-test to explore the effects of fatigue in the lower back muscles. Statistical analysis was performed using pairedsamples t-test.Results: After lower back muscle fatigue, field-goal percentages dropped, and lowest point of CoM was increased during JS. Ankle plantar flexion of the hopping leg during CMJ and JS increased, and their knee flexion angles of the hopping leg were reduced when landing. CMJ and JS changed the contribution ratio of both legs after low back fatigue.Conclusions: Temporary low back muscles fatigue decreased the athletes' performance and causes a change in landing strategy.
(1) Background: To understand the movement characteristics of soccer players when cutting in two directions (45° for the right and left cutting movements) through biomechanical analysis of the lower limbs to identify the cutting direction of the attacker; (2) Methods: A motion analysis system was used to capture the movements of 12 male professional soccer players dribbling to the left and right. Kinematics of the players’ cutting were analyzed, and the paired t-test was used for statistics, with a significant level of α = 0.05; (3) Results: When cutting towards the right, the height of the hip joint during the run-up was low (effect size, ES = 0.41, p = 0.031) at 91.8 ± 7.0 cm. When cutting towards the left, the value was 94.6 ± 6.7 cm. While cutting, the front foot was abducted by 4.3 ± 4.0° at landing when cutting towards the right and adducted by 2.7 ± 5.1° when cutting towards the left (ES = 0.38, p = 0.003); (4) Conclusions: When the attacker carries out the cutting action while approaching the defender, the cutting direction may be predicted by observing the attacker’s hip and foot movements.
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