THE KINEMATIC ANALYSIS OF THE LUMBAR, LUMBOSACRAL, AND HIP JOINTS IN THE DOLPHIN KICK SWIMMING

INTRODUCTION: The dolphin kick movement is commonly used in swimming. The low back pain (LBP) while using the dolphin kick motion is complained by many swimmers and that greatly influences their performance. Cailliet (1968) stated that LBP is caused by kinematic problems in the lumbar, the hip joint and the pelvis. Thus, the kinematic analysis that was included includes the pelvis, the hip joint as well as the lumber vertebrae was necessary for the prevention of the LBP. However, underwater analysis of the dolphin kick was not enough to explain the injury mechanism. Therefore the purpose of this study was the kinematic analysis of the lumbar, the lumbosacral, and the hip joints in the dolphin kick

DETERMINING AN EFFECTIVE STRETCHING TIME FOR ACHILLES TENDON EXTENSION

Stretching exercises are commonly undertaken for sports and rehabilitation. However, it is unknown how an in vivo muscle-tendon unit responds to added stretching stimulation. The purpose of this study was to determine an effective stretching time for Achilles tendon extension. The human medial head of the gastrocnemius muscle was stretched and ultrasonography was used to determine and then compare the length of the Achilles tendon between before and after stretching. Achilles tendon extension for one minute of stretching was 3.4±2.5mm, two 6.8±2.1mm, three 6.9±1.0mm, five 7.2±0.7mm, and ten 7.4±0.8mm. Achilles tendon length was significantly increased for up to two minutes of stretching (

MUSCLE ACTIVITY IN THE SUBJECTS WITH FUNCTIONAL INSTABILITY OF THE ANKLE DURING A SINGLE-LEG DROP JUMP

Ankle sprain is one of the most common injuries experienced sporting participation, and Hertel J (2002) reported it’s recurrence rate is very high( 47-73 %). Presence of residual pain and functional problems (recurrent complaints of “giving way” or repeated sprain) following inversion ankle sprains are often reported. These symptoms of repeated complaints of “giving way” and/or recurrent sprains have been termed functional instability (FI) of the ankle joint with the report of Freeman, Dean and Hanham (1965). Including the report of Konradsen and Ravn (1991) and Hertsell and Spaulding (1999), There are many studies of muscle functions such as muscle strength, muscle activity, muscle response time of ankle joint evertor in the subjects with FI of the ankle joint. However, a few studies have researched muscle activity in the situation actually occurs ankle sprain such as jump landing on the subjects with FI of ankle joint. The purpose of this study was to identify differences in ankle joint muscle activity in subjects with FI of the ankle joint during a single-leg drop jump landing

THE DIFFERENCE OF THE BALANCE ABILITIY BETWEEN THE FUNCTIONAL ANKLE INSTABILITY AND HEALTHY SUBJECTS

Ankle inversion sprains are one of the most common injuries occurring in sports activities. Repeated ankle sprains may lead to chronic ankle instability. In order to prevent the occurrence of ankle instability, it is necessary to understand the difference in the physiological characteristics of the subjects who have chronic ankle instability and those who do not. However, there is little known about the differences between the two. It has been reported that there are two types of ankle instability: mechanical ankle instability (MAI) and functional ankle instability (FAI) which is the disability to which patients refer when they say that their foot tends to “giving way”. In this study, we have attempted to uncover the difference in the center of pressure (COP) and muscle activities during a single leg standing between FAI subjects and healthy subjects with or without an ankle brace

Fluctuation of the Top Location and Avalanches in the Formation Process of a Sandpile

We investigate the formation processes of a sandpile using numerical simulation. We find a new relation between the fluctuation of the motion of the top and the surface state of a sandpile. The top moves frequently as particles are fed one by one every time interval T. The time series of the top location has the power spectrum which obeys a power law, S(f)~f^{\alpha}, and its exponent \alpha depends on T and the system size w. The surface state is characterized by two time scales; the lifetime of an avalanche, T_{a}, and the time required to cause an avalanche, T_{s}. The surface state is fluid-like when T_{a}~T_{s}, and it is solid-like when T_{a}<<T_{s}. Our numerical results show that \alpha is a function of T_{s}/T_{a}.Comment: 15 pages, 13 figure