Sprinting is Art
It’s an Olympic Year and as track and field athletes and coaches, we are EXCITED!!! Every four years, we get to see the best of best in the entire world get to work! It doesn’t matter whether the athlete is first or not, every single athlete is incredibly skilled, fast and powerful – the best in the world.
To get to that level, however, was no accident or simply a result of genetics. To get to that level, just like any other career, it takes many, many years of sacrifice, intensive, and specific work. Sprinters have a lot of strength, power and speed (obviously) and to develop these elements, athletes need the right coach, the right strength program, the right type of sprint training program, nutrition, recovery – all this to perfect every stride and every arm swing because fractions of a second can determine the lively hoods of these talented athletes.
To Get Faster, You Just Have to Run Fast Right?
Getting faster isn’t simply about sprinting fast. There’s a lot more complexity involved to achieving faster times. Yes, sprint training is part of the overall training program but it’s not the only thing. In fact, this is secondary. Strength and power are the big components to help a sprinter get faster. Then comes sprint mechanics. Head position, trunk position, arm swing, knees up, toes up are common cues that sprinters often hear from their coaches – but both coaches and the athlete need to know what those cues mean. Having a knowledgeable coach that can implement the right kind of training to help develop these mechanics really does matter.
Physics of Sprinting
In the sprinting world, good coaches have to understand how physics is at play with every movement the sprinter makes. When sprinters are running, they look like they are floating or bouncing on the track. Gravity is pulling the athlete down, and to help the sprinter move forward, vertical forces have to be greater than the pull of gravity. The force that drives the runner forward is the propulsive force. Running speed is directly related to the magnitude of this force. This is because they are exerting a lot of power with every stride to minimize the time they stay on the ground. The best sprinters in the world accelerate to speeds of over 27 mph with top sprinters making contact and getting off the ground in less than 0.09 seconds all while overcoming impact forces that can exceed 4 times their body-weight. In other words, an Olympic sprinter can push off the ground with a total peak force of more than 1000 pounds. In contrast, the average person can apply 500-600 pounds of total peak force.
Sprinters use a very distinct sprinting gait according to SMU researchers. The widely accepted theory that sprinters were able to sprint fast was due to the spring-mass model, which assumes the legs work essentially like the compression spring of a pogo stick when in contact with the ground. However, research by the SMU Locomotor Performance Laboratory team found that high level sprinters don’t conform to this theory. Rather, “What these sprinters do differently is in their wind up and delivery mechanics. The motion of their limbs in the air is distinct; so even though the duration of their limb-swing phase at top speed does not differ from other runners, the force delivery mechanism differs markedly” according to Dr. Clark. So their research concluded that elite sprinters aren’t bouncing down the track as your average, slow runner would. Instead, sprinters drive their knees up and punch down creating that power to propel the sprinter forward, fast!
Let’s Break It Down
At the start of the race, block positioning has the biggest impact on the sprinters’ performance. An effective sprint start predominantly depends on start block positioning and the body center of gravity in the set position. When the sprinter is positioning themselves in their blocks, they are trying to maximize velocity and acceleration to push against horizontal forces. To do so, the body should be positioned within recommended angles but the athlete also has to be strong and powerful enough to maximize the benefits of the blocks.
Researchers have recommended precise leg/shin angles to accomplish this. Researchers found that the front knee angle should be between 90 and 110 degrees, while the rear leg angle should be between 120 and 135 degrees. Existing strength levels will be the primary factor determining whether the knee angles are closer to 90 and 120 degrees, versus 110 and 135 degrees. This means that weaker athletes will have the hips higher in the air (closer to 120 and 135). Evidence suggests that angles in this range allow for the greatest stretch reflex in the hamstrings, as well as the greatest amount of velocity when exiting the blocks. This is the result of muscle-tendon lengthening of the gastrocnemius and soleus muscles. Longer initial muscle tendon lengths contribute to greater peak ankle joint moment and power. Increasing block angles, demonstrated significantly slower starting velocities and are not recommended according to research.
Stride Length + Stride Frequency = Faster Runner
From start to finish, sprinters go through transition phases, 5 to be exact. At every phase, as the athlete speeds down the track, velocity, acceleration, mass, propulsion forces, horizontal forces, vertical forces, gravity – all these elements interact with the sprinter creating the need for the perfect sprint mechanics, strength and power to help the athlete increase stride length and stride frequency to be faster.
After the starting phase, there is the drive phase where the athlete is pushing to get out of the blocks as fast, as powerful as they can as indicated earlier. This is also the point of acceleration. At the acceleration phase, there is a change in speed where speed is increasing trying to overcome inertia. More technically, acceleration is the rate of change of velocity over time. This takes a great deal of strength and power. There has to be powerful concentric contractions and enough force to overcome inertia. Newton’s Laws of Motion help us understand this. Newton’s first law of motion states that a body continues in a state of rest or uniform motion/velocity in a straight line unless acted upon by an external force. This is inertia. An external force – acceleration – has to be applied for the velocity to change. Newton’s third law of motion states that for every action there is an equal and opposite reaction (action/reaction). For a sprinter, there has to be enough force applied to the ground (ground reaction force) to overcome inertia and accelerate or they’ll slow down.
Top end speed occurs after the athlete can no longer increase their speed or accelerate, at which point maximum velocity or top-end speed has been achieved. Then comes the maintenance phase where the athlete is trying to hold on to their same speed/pace and decelerate as slow as possible to the end.
What About the Rest of the Body
The production of force in running occurs when the support leg moves from hip flexion to hip hyperextension, the gluteal group and the hamstrings pull/push the leg/body forward. But the arms and head are as important as the legs. The arms act like a pendulum with the head acting as a compass. As the runner’s foot strikes the ground, that force causes a torque to be exerted on the body which tends to rotate the torso. To correct for this rotation the runner simultaneously swings the arms to exert a counter torque which will rotate the torso in the opposite direction. The generation of this counter-torque helps keep the body stable and facing forward while sprinting. The arms help cue the knees to lift. During the start and throughout the race, strong arms help drive the knee and foot down, especially during fatigue in a race. With the head in the neutral position, the torque is able to be as efficient as possible. Head positioining also helps guide the leaning of the trunk. When leaning the trunk, it uses gravity to the sprinter’s advantage – the sprinter has to move their legs fast to avoid falling bacause gravity wants to push the body down. However, the lean is from the ankle joint rather then the hips.
Coaching isn’t Just Coaching
To be a fast sprinter, you have to be able to propel forward masterfully. This propelling forward is a result of a lot of strength and power during the foot to ground contact. Coordinating upper and lower body biomechanics has to also be timed perfectly. The best sprint coaches use research based data to develop training programs for their athletes so that everything can come together for the athlete. While it’s great that a coach can identify cues, it’s a lot more complex than just knowing – arms, knees up, drive, hips. All these are important but knowing how each interacts to give the sprinter the perfect race is much more important. And more importantly, it matters how to develop the athlete so that their arms, knees, hip, ankles are doing what they are supposed to be doing.
