It has become more widely known and accepted that strength training as part of an overall programme of athletic performance reduces the likelihood and severity of injury. But how exactly does lifting weights change our risk level?
Resistance training can be described as performing repetitions of a movement against an external force. That force could be gravity, a dumbbell or even elastic training bands. We can use our own body weight or an external implement but the things happening internally at a cellular level are largely the same.
By working against load we increase the level of tension in our muscles and consequently tendons, in order to create movement at the corresponding joint(s). This tension is what leads to a positive adaptation over time if sufficiently overloaded (see this previous article on progressive overload).
All of the bodies tissues have some form of response to pressure and tension (seen as a stressor). When we run, even without having to make each muscle contraction a conscious effort, this process is happening all the time.
A tissue at any given point in time has a certain capacity for tension and it is when the tension we apply (too great or too frequent) exceeds the tissue capacity that we get an injury. All tissue in the body could be affected in this way - bone, tendon, ligament and muscle all get damaged if what we ask of them is too much.
Strength training (a specific type of resistance training) is one method of increasing our tissues ability to handle more demands. It works to increase bone density, tendon strength and stiffness, muscular strength and endurance, joint stability and mobility.
Increasing the amount of strength a muscle has will mean each normal movement you ask it to perform will be at a lower percentage of its overall maximum. This means it can handle more work before it gets tired, injured and damaged.
Similarly, bone is strengthened (density increases) by weight bearing activity such as lifting weights. It’s also true that running goes someway to increase and maintain bone density. However the size of impact and number of impacts mean that during running, bone is often at risk of being overwhelmed. Weight training increases bone density in a more controlled and measurable environment.
Tendons connect our muscles to bones in order to transmit the force and create movement of our skeleton. The tendon itself is a gradual mix of fibres becoming more collagenous until it gradually merges into the boney insertion. The greater force we apply by contracting the muscles, the more the tendon has to handle. As we strength train, over the course of weeks and months our tendons adapt to handle more force with better transmission into the skeleton for more effective and efficient movement.
Strength training with heavy loads and speed training with just body weight are both methods of improving our tendon make up. New collagen gets laid down in the directions we apply force so the muscle and tendon unit (MTU) works better as a whole.
An often overlooked factor in injury is how well your body functions as a whole. How well you move is important. How coordinated you are is important. How much variation your body is capable of is important. Strength training allows a lot of variation, challenges in different planes of motion, improves whole system coordination as well as coordinating individual muscle groups within themselves. Strength training is a discovery of your body in ways you may not have tried before and people derive great benefits from this.
Obviously predicting an injury is a multifactorial complex equation and no one is ever totally free of any risk. What we do know for sure, and that is backed up by a large and growing body of evidence, is that strength training improves our ability to tolerate loads. Ultimately it is your tissue capacity, movement capability and force production that keeps injury at bay.
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By Alex Adams