Anyone who has lifted weights long enough knows that when you start moving maximal weights around it is beneficial to make the body as rigid and fixed as possible. Intuitively it makes sense because we know that something that is soft or bendable is much easier to manipulate than something hard and rigid. It’s why we use steel I-beams to hold up buildings and not columns of jello. Besides being hard to move though, creating tension in our bodies also gives us access to greater strength through something known as Sherrington’s Law of Irradiation.

The Law of Irradiation states, “A muscle working hard recruits the neighboring muscles, and if they are already part of the action, it amplifies their strength. The neural impulses emitted by the contracting muscle reach other muscles and ‘turn them on’ as an electric current starts a motor.” Strength coach Pavel Tsatsouline compares the process of irradiation to the ripples created in water when you drop a pebble into it. “Like a stone dropped in the water sends ripples across the surface, tension spreads—irradiates—from the muscle directly responsible for the job at hand towards others. The bigger the stone, the taller are the waves and the further they spread!”

Our “core” typically gets all the attention anytime we’re lifting heavy and for good reason, but according to this law any tension that is created in the body will help to recruit more muscles and amplify their effect on the movement we’re trying to achieve, so why not squeeze everything?! Start with the object. Sure, in a heavy deadlift your squeezing the bar hard enough to pick it up, but are you really squeezing it as hard as you can? What about in a backsquat? Weighted pull-up? And what are your legs doing in that weighted pull-up? Could you flex them straighter harder or squeeze them together more? We can go on forever like this but the concept remains the same; Creating tension, irradiating, makes you stronger at the task at hand. It’s not only applicable to heavy lifts either. In higher rep metcons, irradiating means more muscles recruited so more potential work and a delay in fatigue! There is a point of diminishing returns because the energy you use on irradiation cannot be applied to the actual task, but you can probably do more than you are and still benefit.

You can test Sherrington’s Law on yourself. Grab your non-dominate hand with the other and squeeze your hand but only using your hand muscles. Now, continue squeezing and create tension in your forearms, then the biceps, then the pec. With each muscle you add to the contraction you will find that you’re able to squeeze your hand harder. See actual measured results for this test HERE.

What does get tight mean to you? Do you have a setup checklist for heavy days? What’s included and what other ways could you create more tension? Tell us in comments!