A KINEMATIC ANALYSES OF STRIDE LENGTH AND STRIDE FREQUENCY DURING RUNNING AT DIFFERENT LEVELS AND VELOCITIES

Abstract

INTRODUCTION The foot landing position (FLP) at touchdown has been hypothesized to be a factor that excessively increases the magnitude of eversion during gait (Inman, 198 1) and stressing the tissues of the foot-ankle complex . (Hamilton, 1985). The purpose of this study was to determine if different FLP during gait would affect the angular kinematics of the foot ankle-complex. METHODS Thirty female participants demonstrating neutral (Neu), toe-in (Toe-1) and toe-out (Toe-0) FLP (5.70 ± l.Oº, -3.80 ± 2.00 and 14.30±2.70, respectively) performed 10 trials of barefoot walking. The locations of markers placed on the foot and leg segments were captured by four digital (100 fps) cameras during the stance phase. Statistical comparisons (p≤ 0.05) among FLP groups were performed using single factor INTRODUCTION AND PURPOSE Many biomechanical studies investigated the relationship between stride frequency (SF) and stride length (SL) for sprinters, middle and long distance runners. It is unclear, sofar, what will happen to this relationship when running is excuted at different velocities and at different levels . This study was conducted to investigate the effect of velocity increments during the graded uphill level (GUL), and the down hill level (DHL) with respect to horizontal level running (HLR) on the SF, SL, stridetime (ST) and stride rate (SR). Nine long distance runners from the Jordanian national team of athletics ran on a treadmill at random orders on (DHL), (GUL) and (HLR) in which the velocity of the treadmill was systematically increased 2 Km/h from 11-23 Km/h, so that seven velocities were determined and controlled. A Sony video camera was positioned at the sagittal plane and was set at 25 image /second. For the purpose of calculation of the variables, a one-minute-time was used in each velocity for each level. The following formulas were used: SL = Distance/SF, ST= Distance time/SF, SR=1/ST One way ANOVA followed by schefe test and trend analysis were used for statistical analyses of the data. RESULTS AND CONCLUSIONS Results were significantly different between velocities, levels, and the interaction between velocity and level for all variables. However, the most useful result revealed the following: 1- When velocities increased the SF & SL increased but ST decreased in all levels. 2- The (SF) , (SL), (ST) and (SR) did not change significantly during (GUL)but there was an inverse relationship between (SF) and (SL). 3- The relationship between( SF) and ( SL) was linear during (DHL) and (HLR), while the (ST) decreased significantly when velocity increased. 4- The (SL) was found to be greater in (DHL) than (HLR) and (GUL) while the (SF) is greater on (HLR) than other levels of the run in all velocities. It was concluded that there was no exact relationship that existed between (SF) and (SL) when running at different velocities and at different levels. It is suggested, therefore, to investigate an optimum relationship for these Kinematics variables with respect to mechanical efficiency.