Why Does Strength Training Improve Running?
The reasons why adaptations from strength training resulted in better running were consistent throughout the literature. They included the following:
- Improved motor requirement patterns and neural adaptations. The neural muscular system may become more efficient in terms of which muscles to turn on, and exactly when to turn them on. When landing on one leg during the stance phase, the strongest, largest muscles need to be ready to both control and stabilize (prime movers), and then accelerate body weight. What is equally important is that before the prime movers can do their job, the smaller muscles that are needed to stabilize the joint (stabilizers), need to contract first in order to give the prime movers the optimal platform from which to create force. Strength training may benefit running by improving the timing and coordination within these muscles. In addition, being able to more effectively turn off muscles not needed at any given time is a plus.
- Strength training results in improved relative intensities. With each step during your run, you’re using a given amount of the maximum strength you can produce. After performing a block of strength training, this maximum amount of strength is now a higher number. With this increase, a lower percentage of the maximum strength available is needed during each stride to obtain that same workload. This may lower the actual number of motor neurons recruited and result in less overall demand. The same changes occur in cycling when considering the forces produced during the pedal stroke.
- Strength training increases muscle stiffness and the ability to absorb and release energy. There is an elastic component in muscle that is very important in running. When contact is made with the ground, some of the energy from the impact can be stored like a spring, and released during push-off. Imagine stretching a rubber band. As you stretch it, it becomes tight and full of stored energy. When you let go, that energy releases and causes the band to snap back. The elastic component of your muscle fibers stores energy in a similar way. When the foot makes contact with the ground, the muscle fibers initially lengthen as they contract to control and decelerate your momentum. When you transition, some of the energy that was stored (like the rubber band) is given back. This gives a slight aid in the movement forward. During running, it’s not a huge amount, but over the course of thousands of steps, it adds up. This results in less energy you need to generate to run at the same pace.
- Strength training may shorten time to peak force. This suggestion was given in a study on maximal strength and running economy in distance runners.(9) I thought it was extremely insightful and wanted to make sure to mention it. It was stated that if the peak force of the muscle contraction occurs earlier, the relaxation after the contraction time in each stride will be increased. The blood flow to exercising muscles occurs almost exclusively between muscle contractions.(10) As a result of this, better circulatory flow through the working muscles during the relaxation time should allow more oxygen and needed substrates to reach the muscle fibers. This increased recovery between contractions could lead to a longer time to exhaustion.
Upcoming section PART 3: Additional Benefits of Strength Training
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