If you ever wonder why we are constantly saying "tighten up" or "squeeze your glutes" or "get organized". This article will do a good job of explaining how paramount the concept of tension is when it comes to safely performing human movement and developing strength.

By Craig Marker
Ph.D., Team Leader

“Your muscles are already capable of lifting a car, they just don’t know it yet.”—Pavel Tsatsouline

Your muscular system is a lot stronger than you might realize. You are already capable of lifting incredibly heavy objects. However, your body has limiting factors built in, so you don’t accidentally do things like tear your tendons from your bones.

These limitations are good, but also tend to be overprotective.There are a few skills of strength we can use that help us (safely) reduce these limitations—and therefore increase our performance.

Get Tight

If you pay attention to StrongFirst content or attend an event, you might notice a consistent message of “get tight.” Why is that referenced so often? Why is tightness important to pushing a heavy kettlebell overhead, pulling a heavy object off the ground, or doing a one-handed push-up?

The first reason might seem obvious. When we press or pull an object from the ground, the force of the press needs to get transferred into the ground. If we are loose like a noodle, our press must overcome the wobble. If we are tight, the force gets directly transferred into the ground. If we were building a multi-story building, we would not start the first floor with thin wood as it would have too much flexion. Rather, we start it with concrete or steel beams.

The second purpose of tension is to inhibit safety signals that protect our muscle and tendons from hurting themselves. These safety mechanisms protect us from danger (seehere and here for great videos that illustrate these mechanisms), and these systems respond quickly and automatically. One example is when you go to the doctor and he or she taps your knee. When a medical professional taps on a ligament in your knee, your knee quickly responds with a kick (called the stretch reflex). The signal does not go to your brain and then you consciously decide to kick. Rather, a signal from the tendon stretching went into your spinal cord and the muscle contracted.


Another safety mechanism, the inverse stretch reflex, leads our muscles to relax when the tendon is pulled too much. If we were able to inhibit this safety signal, we could create a stronger muscular contraction. Tension inhibits the circuitry that tells the muscle to relax.

Charles Sherrington, a famous physiologist, created a model for neuromuscular facilitation and inhibition. Sherrington’s Law of Irradiation describes when muscles recruit nearby muscles.1 Pavel called this law “muscle cheering,” as nearby tight muscles cheer the working muscles to work harder.2

Here is how Pavel described it:

“Make a tight fist. Where do you feel the tension? Your forearm and biceps, right? Even tighter! White knuckles! Do you feel your shoulder and even chest flexing too? In reality, when the demand for force increases, other muscles jump in on the action. 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! … It states that a muscle working hard recruits the neighborhood muscles, and if they are already a part of the action, it amplifies their strength! Not by cheating, as some complement their barbell curls with a back swing, but by ‘cheering’. The neural impulses emitted by the contracting muscle reach other muscles and ‘turn them on’ as electric current starts a motor.”

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