The Role of the Rhythm Step on Pro-Agility Test Performance in Division I Football Players.

Purpose: The pro-agility test is a common test in multiple sports. A common way to start is the crossover step (CS) where athletes start the drill by crossing one leg over the other. However, the rhythm step (RS), initiated by moving one foot medially before crossing the opposite foot over the first, may result in faster time. Therefore, the purpose of this study was to compare the RS to the CS in the pro-agility test. Methods: Thirteen division I college football players (age 21 ± 1.5 years, mass 103.5 ± 18 kg, and stature 1.87 ± .078 m) were recruited to perform both step techniques. Video was analyzed to determine times during the first five yards (t1), the second ten yards (t2), the last five yards (t3), and the total time (ttotal). Additionally, maximum acceleration (amax), time to maximum acceleration (tamax), maximum body lean angle (θlean), and time to reach θlean (tθlean) were measured. Results: Descriptive statistics (mean ± SD) were calculated for all variables. A significant difference between the two techniques was observed at t1 (RS mean 1.56 ± 0.09 s, CS mean 1.62 ± 0.11 s), ttotal (RS mean 4.99 ± 0.35 s, CS mean 5.09 ± 0.35 s), and tamax (RS mean 0.38 ± 0.67, CS mean 0.46 ± 0.61). Conclusion: Overall, the RS appeared to be superior to the CS for reaching peak acceleration faster during the initial phase of the pro-agility drill as well as short distance sprints that are initiated from a standing position.

A comparison of three different start techniques on sprint speed in collegiate linebackers.

The purpose of this study was to compare the track block start (BS), rhythm step (false step) (RS), and forward step (FS) on sprint start ability in male Division I collegiate football linebackers. Although the blocks are not practical in the sport of football, they were used as a gold standard for sprint acceleration. Sixteen collegiate football linebackers (age, 20.9 ± 1.1 years; height, 72 ± 3.0 in; mass, 97 ± 4 kg) performed 3 repetitions each of the BS, FS, and RS. Each sprint was videotaped through 5 m. The time from 0 to 2.5 m (t2.5), 0 to 5 m (t5), and 2.5 to 5 m (tsplit) were calculated for each trial using all 3 different techniques, and the best times for each treatment was recorded. Block start resulted in significantly lower t2.5 and t5 compared with RS and FS. Rhythm step had significantly lower t2.5 and t5 compared with FS. There was no difference in tsplit between any of the 3 treatments. The results indicate that using the blocks is optimal for sprint performance through 2.5 and 5 m. Rhythm step outperformed FS through both 2.5 and 5 m, suggesting that for collegiate football linebackers, RS is superior to FS.

Varus/valgus and internal/external torsional knee joint stiffness differs between sexes.

BACKGROUND: Torsional joint stiffness is thought to play a role in the observed sex bias in noncontact anterior cruciate ligament injury rates. HYPOTHESIS: Women will exhibit lower torsional stiffness values of the knee in response to varus/valgus and internal/external rotations than will men. STUDY DESIGN: Controlled laboratory study. METHODS: Knee kinematics of 20 university students (10 men, 27.3 +/- 3.4 years, 177.3 +/- 6.8 cm, 81.1 +/- 7.0 kg; 10 women, 22.9 +/- 1.5 years, 169.0 +/- 7.1 cm, 66.1 +/- 11.4 kg) were measured while 0 to 10 N . m of varus and valgus torques were applied with the subject nonweightbearing and while 0 to 5 N . m of internal and external torques were applied with the subject nonweightbearing and weightbearing with the use of a custom joint testing device. Joint stiffness values were calculated at 1-N . m increments. RESULTS: When low magnitudes of torque were applied to the knee, women had significantly lower stiffness values than did men. With the exception of applied external torque with the joint weightbearing and varus torque with the joint nonweightbearing, women demonstrated an increase in joint stiffness as the magnitude of torque increased from lower to higher magnitudes. In contrast, for the men, joint stiffness values remained unchanged as the magnitude of applied torque increased. CONCLUSION: Women exhibited lower knee stiffness in response to low magnitudes of applied torque compared to men and demonstrated an increase of joint stiffness as the magnitude of applied torque increased. CLINICAL RELEVANCE: The decreased stiffness behavior of the knee in response to low torques that was observed for women may have a role in detrimentally affecting knee biomechanics and resulting neuromuscular function, particularly when an individual transitions from nonweightbearing to weightbearing.