Sprint Mechanics, Training, and Agility in Sports

Sprint Stride Phases and Ground Contact

Ground Contact (Heel Strike, Amortization, Toe Off)

During ground contact, the foot should strike with weight on the ball of the feet. The strike leg should aggressively straighten down and underneath the body to the ground contact point.

Recovery (Leg Extension, Forward Swing, Foot Descent)

The strike leg should aggressively extend, and the forward swing should follow while the other leg is going through contact. The recovery leg should follow a path straight up toward the buttock, the knee should rise, and the thigh should be parallel to the ground. The foot should drop below the knee, making the knee at a 90-degree angle.

Sprint Acceleration and Maximum Velocity Distances

Many field sport athletes can attain maximum velocity at approximately 20–30 yards or meters, spending 20–30 yards on the acceleration phase. Track athletes can spend more time in the acceleration phase, reaching maximum velocity between 40–50 yards or meters.

Resultant Force Vectors During Sprinting

The resultant ground reaction force is highest during maximal speed. From acceleration to maximum velocity, the vertical ground reaction force (GRF) also increases; however, the horizontal GRF remains the same. The vertical ground reaction force remains the same due to the torso being in an upright position.

Assisted vs. Resisted Sprinting

While both assisted and resisted sprinting increases speed, assisted sprinting is usually used to improve the top speed phase, while resisted sprinting usually improves the acceleration phase. Training protocols such as plyometrics, free sprinting, and resisted sprinting will enhance acceleration in field sport athletes, partially through improved reactive power, which will encourage step length. Any attempt to further improve acceleration by increasing step frequency will require the introduction of another training stimulus (assisted sprinting).

Linear Speed Training Program for Football: 6 Drills

1. Leg Drive: Mountain climbers on a wall (focus on driving the knee and extending the hips)
2. Leg Recovery: Combine active and passive range of motion (ROM) to warm up and increase blood flow to leg muscles.
3. Force Development & Step Length: Incline runs (focus on force/power)
4. Step Frequency: Run on decline surfaces (more steps)
5. Acceleration: Sled pushes (power)
6. Maximum Velocity: Flying 20s sprint drill (emphasis on top speed rather than acceleration)

Agility and Change of Direction (COD)

Agility is classified as the ability to rapidly change direction or the ability to rapidly and accurately change direction. There are two classifications:

1. Perceptual and decision-making factors
2. Change of direction speed

Perceptual and decision-making factors can be exemplified by a quarterback avoiding tackles while looking for a pass.