Change in shock attenuation during marathon running

The purpose of this study was to estimate shock attenuation during marathon running using inertial measurement units attached on the foot and sacrum. Eleven male runners were recruited as subjects from the participants of the official marathon race. Two inertial measurement units (IMUs) attached on the foot and sacrum operated at 200 Hz and stored three axis acceleration data in the memory through the marathon race. Absolute acceleration was transferred power spectrum density (PSD) by FFT and a transfer function was calculated by PSD of the sacrum relative to the foot. The results showed that the impact acceleration was recognized from 11 to 18 Hz at the foot and was attenuated between the foot and the sacrum. It is suggested that this method could be useful to evaluate shock attenuation during endurance running easily and might be used to give appropriate feedback in real time to decrease injury risk

ANALYSIS OF THE TRANSFORMATION OF THE VELOCITY OF THE CENTER OF GRAVITY IN RUNNING SINGLE LEG HORIZONTAL JUMP

The purpose of this study was to analyze the transformation of the center of gravity (CG) in the running single leg horizontal jump and to investigate the influence of the forward rotation of the takeoff leg in achieving vertical CG velocity. The subjects were 98 male long jumpers, whose mean best official jump among their recorded trials was 7.16 ± 0.66 m. Their takeoff motion was videotaped with two high-speed cameras. Horizontal CG velocity at touchdown and vertical CG velocity at toe-off had significantly positive correlations with jumping distance; the decrease in horizontal CG velocity during the takeoff phase was significantly and negatively correlated with jumping distance. Forward rotation of the spring-mass model did not contribute to an increase in vertical CG velocity, although it did contribute to an increase in horizontal CG velocity just before toe-off

A BIOMECHANICAL ANALYSIS OF CUTTING MOVEMENT WHILE RUNNING WITH CHANGE IN DIRECTIONS

The purpose of this study was to investigate techniques of change of direction during running, and obtain findings to improve cutting movement. Thirty six male university students, who are soccer, basketball, rugby, and handball players, participanted in this study as subjects. In the experimental trials, subjects ran 30m straight and zigzag run with five changes of direction of 30, 60 and 90 degrees using side and cross step. Twenty subject’s runs were chosen for further analysis based on the time of 30m straight run and an index of change of direction. There were significant correlations between the time of zigzag running and the index of change of direction. The results suggested that the time of zigzag running was affected not only by the ability to run straight but also by the techniques of changing direction in running

CHANGES IN MECHANICAL WORK AND JOINT CONTRIBUTIONS OF THE LOWER LIMB JOINTS DUE TO FATIGUE IN DISTANCE RUNNING

The purpose of this study was to investigate changes in work, and joint contributions by the lower limb joints in response to fatigue in distance running and to obtain insight into maintaining the running velocity. Fifteen male distance runners ran a 4000 m trial in even pace. Running motion and ground reaction force were collected each lap and two- imensional inverse dynamics were performed to calculate the lower limb joint torques, powers and work in the initial, middle and final stages of the trial. The joint contributions of the lower limb joints represented the ratio of the work of each joint to the total mechanical work. Results indicated that the mechanical work and joint contribution did not change significantly from the initial to the final stages of the trial. The joint with the largest contribution decreased the joint contribution from the middle to the final stage, although these changes varied runner by runner. It was concluded that the lower limb joints could compensate each other to maintain the total work output during the trial

THE INTERRELATIONSHIP OF JOINT STIFFNESS IN DROP JUMP UNDER DIFFERENT CONDITIONS: A SINGLE-SUBJECT DESIGN

The purpose of this study was to examine the relationship between leg stiffness and joint stiffness in the various conditions of drop jump. A women’s athlete was recruited as the subject and asked to perform drop jump from different height of box to another box in different horizontal distance between them. The leg stiffness is influenced on the contact time and relates to knee and ankle joint stiffness. The change in leg length is greater at great horizontal distance and peak ground reaction force is greater at higher box of jump off and up. The contact time was also related to the horizontal distance and to the knee and ankle joint stiffness, peak ankle joint torque and minimum knee joint angle. These might suggest that leg stiffness influenced by ankle and knee joint stiffness due to peak ankle joint torque and knee joint angular displacement to adjust the conditions of drop jump

EFFECTS OF PACING STRATEGIES ON THE RUNNING MOTION OF MALE 800 METER RUNNERS

The purpose of this study was to investigate the effects of different pacing on running motion for male 800 m runners in official competitions. Ten male 800m runners were videotaped (60Hz) from the side positioned the marks of 150m (1st mark), 350m (2nd mark), 550m (3rd mark) and 750m (4th mark) of the 800m race. Kinematics and Kinetics variables were calculated. We divided ten subjects into two groups: Positive-type (POS) which consisted of five subjects with the fastest average running velocity of the 1st and 2nd marks running velocity (running velocity), Negative-type (NEG), which consisted of the five other subjects. In POS, the running velocity, the stride length per height and the shank angular velocity of the support leg were significantly decreased along the race, and the trunk inclined forward than NEG. However, the hip extensor torque, power and the knee flexor torque at the late recovery phase did not decrease. In NEG, the running velocity, the relative step frequency, the hip flexor torque at the early recovery phase, the hip extensor torque and the knee flexor torque at the late recovery phase were significantly increased at the late half of the race. The thigh and shank angular velocity of the support leg were maintained. It was concluded that the running motion of 800 m runners were affected by the pacing strategy

EFFECT OF BIOMECHANICAL FACTORS ON ENERGY COST DURING RUNNING AT VARYING INCLINES

This study aimed to investigate the characteristics of muscular activity of a support leg that affected energy cost at different inclinations of a treadmill while running. Eleven male Japanese distance runners ran on a treadmill at 13.5 km·h��1 for 3 min at five different inclinations���� ��6%, ��3%, 0%, +3%, and +6%. Running kinematics, electromyography (EMG), expired gases, and blood lactate levels were measured. The following results were obtained: 1) the energy cost and integrated EMG (iEMG) of the vastus lateralis (VL) muscle increased with increasing inclination, and 2) iEMG of the VL and gluteus maximus (GM) muscles positively correlated with the vertical displacement of the body’s center of mass and with a maximal angle of the thigh during the contact phase. Thus, the muscular activities of VL and GM might increase the energy cost while running at an inclination

MECHANICAL WORK CALCULATION METHODS TO EVALUATE DISTANCE RUNNERS

The main purpose of this study was to discuss mechanical work calculation methods for evaluating the effectiveness of running at six different speed. Nineteen male middle and long distance runners were participated in the study, as subjects. Biomechanical measurements were in order to record running motion and ground reaction force. Mechanical work was calculated using two methods: the joint torque power method (WTP) and the mechanical energy method (WME). Physiological measurements were recorded using submaximal and maximal incremental exercise tests on a treadmill. These results were as follows: 1) WTP was significantly larger than WME. 2) WTP/W/TIME was stronger related to velocity and aerobic demands. These findings suggest that regression equation between WTP/W/TIME and velocity evaluate effectiveness of distance runner

EFFECT OF SHOES AND TIGHTS WITH THE SUPPORT FUNCTION ON SUPPORT LEG DURING RUNNING

The study aimed to clarify the effect of shoes (WS) and tights (BT) with the support function on support leg during running. The subjects, eight female Japanese runners, ran for 1-min periods on a treadmill. Motion, electromyography (EMG), acceleration and angular velocity were recorded. The following results were obtained: 1) there was difference in the pronation angle between support shoes and non-support shoes. 2) There was difference in angle of lower leg in frontal plane between support shoes and non-support shoes. 3) Combination of WS and BT might decrease angle of the foot and shank in frontal plane and stabilize the trunk, but the effect varies depending on subjects

RUNNING ECONOMY AND GASTROCNEMIUS MUSCLE LENGTH DURING RUNNING FOR KENYAN AND JAPANESE ELITE DISTANCE RUNNERS

The purpose of this study was to compare running economy and gastrocnemius muscle length during running for Kenyan and Japanese elite distance runners. Running economy was measured on the treadmill at 340 m/min while running motion was captured on the inside straight track at their racing speed. Gastrocnemius muscle length was estimated by the equation of Grieve et al. (1978) during the support phase at race speed running on the track. Kenyan runners showed higher running economy and smaller shortening length change of gastrocnemius during support phase than Japanese. These results suggest that shortening gastrocnemius during support phase of the running relates to running economy