Muscles are important, but the real secret is using training and technique to store and reuse elastic energy in the best way possible – and that means making the most of your tendons. By understanding how this power is produced, we can help people walk, run and jump into older age and how to walk again after injury or illness.
Muscles Are Strong, but Slow
Muscles produce most of their force through the interactions of two proteins: actin and myosin. The rotating, globular “head” region of the long myosin filament attaches to the rod-like actin to pull it along in a sweeping motion, like an oar producing force to pull a boat along the water. So actin and myosin filaments form powerful mini motors.Trillions of these mini motors together the large forces we need every day to walk upstairs, carry our shopping bags, or take the lid off a jar.
The head region of myosin is only 20 nanometres long. It’s so small that there’s no point comparing its size to a human hair, because it would barely even cross a handful of DNA molecules laid side by side.
Because it’s so short and only pulls actin a small distance in each stroke, a large number of strokes are needed to shorten a muscle by any distance. It’s like using first gear to get up a hill in a car or on a bike – good for force, but not for speed.
Energy Return Systems
So if the muscles aren’t producing the power to move a body at high speed, where is it coming from? Humans, like most other animals on Earth, make use of an “energy return system”: something that can store energy and release it rapidly when needed.Our energy return systems are made of a relatively long, stretchy tendon attached to a strong muscle. When the muscle produces force it stretches the tendon, storing elastic energy. The subsequent recoil of the tendon then generates a power far superior to our muscles. Our tendons are power amplifiers.
There are several techniques we can use to increase energy storage. The most important is to first move in the opposite direction to the desired movement (a “countermovement”) so the muscle force is already high when the proper movement begins. Most of us learn this strategy when we’re young, when we first dip down before we jump upwards, or we draw our bat or racquet backwards before swinging it forwards.
The technique we use is key to maximising our elastic potential, and Olympic athletes spend years trying to optimise it.
Can We Improve Our Energy Return System?
The capacity to store and release elastic energy is partly determined by genetics, but it’s also something we can improve through training. Not only can training improve your technique, heavy strength training and other methods can also make your tendons stiffer.The greatest power during walking, running and jumping is produced at the ankle joint. This is an important target for athletes, but also for anyone who wants to maintain their walking capacity as they age.