ORIGINAL : Kinematic Comparisons of Kettlebell Two-Arm Swings by Skill Level

( Chang Yei Back ),( Ji Yong Joo ),( Young Kwan Kim ) 한국운동역학회 2016 한국운동역학회지 Vol.26 No.1

Objective: The purposes of this study were to compare the kinematics of a two-arm kettlebell swing between experts and beginners and to identify the correct postures and biomechanical key points in an attempt to prevent sports injuries induced by a kettlebell swing. Methods: Four experts (height, 169.7 ± 1.5 cm; weight, 70.5 ± 1.8 kg; age, 32.0 ± 1.0 years) licensed to teach kettlebell exercises and three beginners (height, 173.7 ± 4.1 cm; weight, 78.3 ± 3.8 kg; age, 30.0 ± 1.4 years) with no kettlebell exercise experience participated in this study. Each participant performed 15 repetitions of a two-arm kettlebell swing using a 16-kg weight. Joint angles, angular velocities, and peak angular velocity sequences were calculated and compared between the two groups. Results: Large ranges of motion (ROM) of the pelvic angle and hip joints were detected in the experts, while beginners showed greater ROM of the shoulder joint. Peak angular velocity magnitudes and sequences were significantly different between the two groups. Experts lifted the kettlebell upward using the hip joints, pelvis, and shoulder joints (proximal to distal order) sequentially and lowered it using the reverse order of peak angular velocities from the shoulder to hip joints. Conclusion: Mobility of the pelvic segment and hip joint are required, while stability of the other joints is needed to produce appropriate two-arm kettlebell swings. The activation and coordination of the gluteal and hamstring muscles are key points in kettlebell exercises.

Kinematic Comparisons of Kettlebell Two-Arm Swings by Skill Level

Back, Chang-Yei,Joo, Ji-Yong,Kim, Young-Kwan Korean Society of Sport Biomechanics 2016 한국운동역학회지 Vol.26 No.1

Objective: The purposes of this study were to compare the kinematics of a two-arm kettlebell swing between experts and beginners and to identify the correct postures and biomechanical key points in an attempt to prevent sports injuries induced by a kettlebell swing. Methods: Four experts (height, $169.7{\pm}1.5cm$; weight, $70.5{\pm}1.8kg$; age, $32.0{\pm}1.0years$) licensed to teach kettlebell exercises and three beginners (height, $173.7{\pm}4.1cm$; weight, $78.3{\pm}3.8kg$; age, $30.0{\pm}1.4years$) with no kettlebell exercise experience participated in this study. Each participant performed 15 repetitions of a two-arm kettlebell swing using a 16-kg weight. Joint angles, angular velocities, and peak angular velocity sequences were calculated and compared between the two groups. Results: Large ranges of motion (ROM) of the pelvic angle and hip joints were detected in the experts, while beginners showed greater ROM of the shoulder joint. Peak angular velocity magnitudes and sequences were significantly different between the two groups. Experts lifted the kettlebell upward using the hip joints, pelvis, and shoulder joints (proximal to distal order) sequentially and lowered it using the reverse order of peak angular velocities from the shoulder to hip joints. Conclusion: Mobility of the pelvic segment and hip joint are required, while stability of the other joints is needed to produce appropriate two-arm kettlebell swings. The activation and coordination of the gluteal and hamstring muscles are key points in kettlebell exercises.

체성감각 처치를 초보자에게 적용한 케틀벨 투암 스윙의 운동역학적 효과 비교: 관절 가동범위와 근활성도를 중심으로

Back, Yei-Chang,Kim, Young-Kwan 한국운동역학회 2019 한국운동역학회지 Vol.29 No.2

Objective: The purpose of this study was to investigate biomechanical comparisons of kettlebell two-arm swings after different somatosensory interventions on joint ranges of motion (ROM) and muscle activations. Method: Fourteen kettelbell novices (age: $22.92{\pm}3.23yrs$, mass: $75.75{\pm}9.94kg$, height: $172.03{\pm}5.49cm$), consisting of male college students, participated in this study and performed two-arm kettlebell swings in different conditions. Three different somatosensory interventions were the applications of heavy mass kettlebell (20 kg), taping on gluteus muscles, and unstable mat condition. All subjects performed pre-intervention swings and post-intervention swings, respectively. Statistical analysis were performed on results of joint kinematics and electromyographies of major muscles. Results: Results showed significant increases in ROM of hip and decreases in ROM of shoulder after unstable mat trials. In addition, the application of unstable mat during kettlebell swings induced higher muscle activations in gluteus maximus muscle during only upward phase of two-arm kettlebell swings. Conclusion: For beginner, the application of unstable surface would increase in hip joint ranges of motion with enhancement of gluteus muscles.

체성감각 처치를 초보자에게 적용한 케틀벨 투암 스윙의 운동역학적 효과 비교: 관절 가동범위와 근활성도를 중심으로

( Yei-chang Back ),( Young-kwan Kim ) 한국운동역학회 2019 한국운동역학회지 Vol.29 No.2

Objective: The purpose of this study was to investigate biomechanical comparisons of kettlebell two-arm swings after different somatosensory interventions on joint ranges of motion (ROM) and muscle activations. Method: Fourteen kettelbell novices (age: 22.92±3.23 yrs, mass: 75.75±9.94 kg, height: 172.03± 5.49 cm), consisting of male college students, participated in this study and performed two-arm kettlebell swings in different conditions. Three different somatosensory interventions were the applications of heavy mass kettlebell (20 kg), taping on gluteus muscles, and unstable mat condition. All subjects performed pre-intervention swings and post-intervention swings, respectively. Statistical analysis were performed on results of joint kinematics and electromyographies of major muscles. Results: Results showed significant increases in ROM of hip and decreases in ROM of shoulder after unstable mat trials. In addition, the application of unstable mat during kettlebell swings induced higher muscle activations in gluteus maximus muscle during only upward phase of two-arm kettlebell swings. Conclusion: For beginner, the application of unstable surface would increase in hip joint ranges of motion with enhancement of gluteus muscles.

오버헤드 타격 동작에서 발달장애아동과 비장애아동의 상지 운동학 변인 비교

백창의 ( Chang Yei Back ),김영관 ( Young Kwan Kim ) 한국특수체육학회 2014 한국특수체육학회지 Vol.22 No.2

본 연구의 목적은 오버 헤드 타격 동작 시 발달장애아동과 비장애아동 사이에 발생하는 운동학적 차이를 알아보고자, 남자 발달장애아동 6명과 비장애아동 7명을 대상으로 동작분석을 실시하였다. 실험도구로는 유아용 라켓과 스펀지 테니스공을 이용하였다. 연구보조자가 4m 거리에서 대상 아동의 머리 위쪽으로 공을 던져주면서 아동에게 머리 위로 손을 뻗어 라켓 중심에 정확하고 빠르게 타격하라고 요청하였다. 3차원 전자기식 동작 측정 시스템을 이용하여 과제 수행할 때 발생하는 3차원 관절각과 관절각속도 값을 구한후 집단간 비교를 실시하였다. 실험 결과 몸통, 어깨, 및 팔꿈치의 움직임에서 두 집단간 차이가 있었다. 발달장애아동은 치기할 때 몸통분절을 효율적으로 사용하지 않았기 때문에 보상 행위로 과도한 어깨와 팔꿈치 움직임을 나타내었다. 또한 발달장애아동의 분절 속도와 각속도 크기는 비장애아동보다 유의하게 낮았다. 따라서 코치가 오버헤드 스윙 동작을 지도할 때 발달장애아동이 몸통과 상지 분절을 효율적으로 활용할 수 있게 해 주는 것이 필요하다. The purpose of this study was to investigate kinematic differences between developmental disabled children(DDC) and normal children (NC) during overhead striking motion. Six DDC and 7 NC participated in this study voluntarily. They stroke an incoming from a 4m distance with a racket five times. Three-dimensional body segment motions were recorded by the use of electromagnetic motion capturing system. Joint angles and joint angular velocity were compared between two groups. Results indicated that there were significant kinematic difference on trunk, shoulder, and elbow motions between DDC and NC. DDC did not utilize trunk segment efficiently and consequently compensatory shoulder and elbow motions were followed. In addition, the magnitude of segmental and angular velocities of DDC were significantly lower than those of NC. Rehabilitation exercise stimulating the proximal segment or/and core section motions to DDC is strongly recommended to improve DDC’s fundamental motor skills.

ORIGINAL : Kinematic Comparisons of the Tsukahara Vault between a Top-level Athlete and Sublevel Collegiate Athletes

( Cheol Hee Park ),( Young Kwan Kim ),( Chang Yei Back ) 한국운동역학회 2016 한국운동역학회지 Vol.26 No.1

Objective: The purpose of this study was to investigate kinematic comparisons of Tsukahara vault in gymnastics between a top-level athlete and sublevel collegiate athletes in order to obtain information on key biomechanical points for successful Tsukahara vaults. Methods: An Olympic gold medalist (height, 160 cm; weight, 52 kg; age, 25 years) and five sublevel collegiate gymnasts (height, 168.2 ± 3.4 cm; weight, 59.6 ± 3.1 kg; age, 23.2 ± 1.6 years) participated in this study. They repeatedly performed Tsukahara vaults including one somersault. Fourteen motion-capturing cameras were used to collect the trajectories of 26 body markers during Tsukahara vaults. Event time, displacement and velocity of the center of mass, joint angles, the distance between the two hands on the horse, and averaged horizontal and vertical impact forces were calculated and compared. Results: The top-level athlete showed a larger range of motion (ROM) of the hip and knee joints compared to sublevel collegiate athletes during board contact. During horse contact, the top-level athlete had a narrow distance between the two hands with extended elbows and shoulders in order to produce a strong blocking force from the horse with a shorter contact time. At the moment of horse take-off, reactive hip extension of the top-level athlete enhanced propulsive take-off velocity and hip posture during post-flight phase. Conclusion: Even though a high velocity of the center of mass is important, the posture and interactive action during horse contact is crucial to post-flight performance and the advanced performance of Tsukahara vaults.

Kinematic Comparisons of the Tsukahara Vault between a Top-level Athlete and Sublevel Collegiate Athletes

Park, Cheol-Hee,Kim, Young-Kwan,Back, Chang-Yei Korean Society of Sport Biomechanics 2016 한국운동역학회지 Vol.26 No.1

Objective: The purpose of this study was to investigate kinematic comparisons of Tsukahara vault in gymnastics between a top-level athlete and sublevel collegiate athletes in order to obtain information on key biomechanical points for successful Tsukahara vaults. Methods: An Olympic gold medalist (height, 160 cm; weight, 52 kg; age, 25 years) and five sublevel collegiate gymnasts (height, $168.2{\pm}3.4cm$; weight, $59.6{\pm}3.1kg$; age, $23.2{\pm}1.6years$) participated in this study. They repeatedly performed Tsukahara vaults including one somersault. Fourteen motion-capturing cameras were used to collect the trajectories of 26 body markers during Tsukahara vaults. Event time, displacement and velocity of the center of mass, joint angles, the distance between the two hands on the horse, and averaged horizontal and vertical impact forces were calculated and compared. Results: The top-level athlete showed a larger range of motion (ROM) of the hip and knee joints compared to sublevel collegiate athletes during board contact. During horse contact, the top-level athlete had a narrow distance between the two hands with extended elbows and shoulders in order to produce a strong blocking force from the horse with a shorter contact time. At the moment of horse take-off, reactive hip extension of the top-level athlete enhanced propulsive take-off velocity and hip posture during post-flight phase. Conclusion: Even though a high velocity of the center of mass is important, the posture and interactive action during horse contact is crucial to post-flight performance and the advanced performance of Tsukahara vaults.