Sports Training 3: The Science behind Why Lighter Sets Feel Easier After Heavier Sets

Have you ever noticed that after lifting heavy weights, lighter sets feel easier? There’s a scientific reason behind this phenomenon. When we lift weights, our bodies are constantly trying to conserve energy and minimize the amount of effort required to lift a certain weight. To achieve this, our bodies first recruit low-threshold motor units, which are made up of smaller nerve cells that innervate relatively smaller numbers of slow-twitch muscle fibers. However, when we increase the weight on the bar, our bodies are forced to recruit higher-threshold motor units, which have larger nerve cells that innervate hundreds of fast-twitch muscle fibers.

So, when we drop down to a lower weight after lifting heavy, these higher-threshold motor units are still activated and ready to go, making the lighter weight feel easier to lift. This is known as Henneman’s Size Principle, which is a principle in physiology and neuroscience that described the order in which motor units are recruited during muscle contractions. By understanding how our bodies recruit different types of motor units, we can optimize our training and make the most of our workouts.