Relationship of Crural Index and Speed in Collegiate Softball Players

Background/Purpose: Speed plays a critical role in the majority of competitive sports such as softball. Many factors including weight, height, sprinting mechanics and leg length, affect an athlete’s speed. The purpose of this study was to determine the relationship between sprint speed (SS) and crural index (CI) in collegiate softball players. Twenty-two female collegiate softball players (ht., cm = 168.48 ± 5.90; wt., kg = 71.02 ± 14.70; age, years = 19.73 ± 1.03) participated in this IRB approved study. It was hypothesized that the higher the CI, the faster the athlete’s SS. 

Method: Athlete’s leg length measurements taken included length of the full leg (hip joint center to ankle joint center), length of the femur (hip joint center to center of knee joint) and length of the tibia (center of the knee joint to the center of the ankle joint). The CI was calculated by dividing the length of the tibia by the length of the femur and multiplying by 100.  A Brower Timing TC-system was used to time subjects running two twenty-yard sprints followed by two forty-yard sprints with three to six minutes of rest between sprints. A Pearson Product Moment correlation was run in Minitab 16 to determine the relationship between SS and CI at the 0.05 level.

Analysis/Results: Averages of the two twenty-yard sprints (3.02 ± 0.14) correlated to CI (0.92 ± 0.05) had a moderate negative relationship (r = -0.50) and were statistically significant (p = 0.01).  Averages of the two forty-yard sprints (5.70 ± 0.33) correlated to CI (0.92 ± 0.05) had a high negative relationship (r = -0.65) and were also statistically significant (p = 0.00).

Conclusions:   Based on the results, softball players with a higher CI do have faster SS. There was a slightly stronger relationship between the forty-yard SS and CI than the twenty-yard SS and CI possibly due to the athlete’s ability to reach full speed over a longer distance. The results of this research are of importance to softball players and coaches and should be taken into consideration when selecting athletes to sprint 20 and 40 yards.