This study investigated mechanical factors related to performance of the luge start movement and kinetic parameters flowing among limb segments. Using two synchronized video cameras (60fps), the start movements of seven elite male luge athletes were recorded as they participated in an all-Japan luge championship. Joint torque and power were calculated using a DLT technique and bar-reaction force measurements (50Hz). Start time showed a significant correlation (r=0.882, p<0.001) with goal time and Center of mass (CM) velocity at the moment of start bar release (r=0.577, p<0.05). The characteristics of the start movement for the elite group was as followed: In the pulling-back phase, mechanical energy resulting from hip and shoulder joint torque flowed into the lower limbs. At the furthermost pulling-back position, their mechanical energy flowed into the trunk to be supplied to the hip and shoulder extensors as elastic energy. In the luge-moving-forward phase, the mechanical energy of the trunk was pulled into the lower limbs due to extension torque in the hip and shoulder joints at the onset of movement; it flowed to the trunk until just before bar-release position. These results indicate that elastic energy stored in the quick-pulling-back motion may be useful for delivering the forward large CM velocity.

Starting technique is one of the most important factors for race performance in competitive swimming. Start phase (0-15m) is divided into five sub phases, namely, block, flight, entry, glide and stroke phases. There are many studies about both the kinematic and kinetic analyses in the block and the flight phases on competitive swimming start. However, there have been very few studies for entry phase. Therefore, the purpose of this study was to examine the relationship between techniques in entry phase and the performance of the swimming start. Sixteen collegiate elite male swimmers performed maximal efforts competitive swimming start followed by 25m freestyle swim. The mean value of the swimmer’s elapsed time at 15m on 25m maximum effort freestyle swimming trial was 6.86±0.24 sec. A correlation analysis was conducted to examine relationships between performance of start phase (0-15m time) and kinematic variables. There was a significant negative correlation between entry speed and the performance of 15m swim (r=-0.573 p<0.05). Also, there was a significant positive correlation between angle of attack for entry and the performance of 15m swim (r=0.641 p<0.01). There was a significant positive correlation between attitude angle of for entry and the performance of 15m swim (r=0.605 p<0.05). Also, there was a significant positive correlation between glide speed and the performance of 15m swim (r=0.543 p<0.05).
These results suggest that the start performance is influenced by speed, angle of attack (the angle between velocity vector of center of mass and the line from center of mass to hand at entry) and attitude angle (the angle between line from great trochanter to hand at entry and the water surface) for entry. There was a positive correlation between horizontal take off velocity and performance of start phase. These results indicated that a swimmer needs to accelerate the center of mass on the starting block to produce a fast entry speed.
In addition, the results of this study show that the attitude angle and the angle of attack affect the performance of start phase. Therefore, the good performance is attained with high entry speed, small attitude angle and the small angle of attack.