Acceleration versus maximum speed sprinting: A pilot study assessing sprint performance, eccentric knee flexor strength, and muscle architecture

The objective of this study was to implement a pilot protocol to investigate the effects of acceleration and maximum speed sprint training on sprint performance, eccentric knee flexor strength, and knee flexor muscle architecture. A pre-and post-intervention study including a control group was employed. Twelve male field sport athletes (age = 23.1 3.2 years, height = 180.1 8.3 cm, body mass = 80.1 6.4 kg) were recruited to participate in this study. Participants were allocated to either an acceleration, maximum speed, or a control group. Participants completed pre-and post-testing consisting of a 40-metre sprint, eccentric knee flexor strength assessment, and an ultrasound of the Biceps Femoris Long Head (BFLH). Training interventions were completed over 6 weeks with 2 sessions per week. Knee flexor muscle soreness data was collected using a 10-point scale. BFLH fascicle length increased by 1.95 cm in the acceleration group and 1.67cm in the maximum speed group. Trivial changes were reported in eccentric knee flexor strength for all three groups. Both acceleration and maximum speed training improved sprint performance. Both forms of sprint training were effective for increasing BFLH fascicle length. Maximum speed sprinting may offer a prophylactic benefit for modifiable hamstring injury risk factors. These findings should be confirmed with studies on a larger scale.