Time Under Tension (T.U.T)
The term ‘time under tension’ or TUT for short, refers to the amount of time your muscles are under a load during resistance training. We track this time by changing repetition tempo which is simply rep speed. Tempo is tracked by noting the time it takes for a muscle to contract during each phase of the muscle action spectrum. There are three main types of muscle contractions:
A muscle produces tension during each type of contraction. The difference is in the length of the muscle during activation. In an eccentric contraction, a muscle lengthens as it produces tension so it can slow down a movement. There is no length change during an isometric contraction, but tension is still produced to stabilise the body during a movement. During a concentric contraction, the muscle shortens as it speeds up a movement. For example;
- Bench Press – Pressing the weight (concentric), lowering the weight (eccentric), pausing, holding or applying force in a static position (isometric).
Essentially, ‘tempo’ in weight training refers to the speed that you lift the weight (the concentric phase of movement) and how quickly you lower the weight (the eccentric phase of movement).
Tempo is typically shown as a 3 or 4 digit number, with each number referring to the speed at which part of the exercise should be performed.
- The First Number – The first number refers to the lowering (eccentric) phase of the lift. Using our bench example, the 4 represents the amount of time (in seconds) that it should take you to descend to the bottom of the press. The first number always refers to the lowering/eccentric phase, even if the movement begins with the ascending/concentric phase, such as in a pull-up.
- The Second Number – The second number refers to the amount of time spent in the bottom position or ‘stretch’ position of the lift, the point in which the lift transitions from lowering to ascending. In our bench example, the prescribed 0 means that the athlete should reach the bottom position and immediately begin their ascent. If, however, the prescription was 32X0, the athlete would be expected to pause for 2 seconds at the bottom position.
- The Third Number – The third number refers to ascending (concentric contraction) phase of the lift, in other words; the amount of time it takes you to get to the top of the lift. You’re correct in realising X is not a number. The X signifies that the athlete should EXPLODE the weight up as quickly as possible. In many cases, this will not be very fast, but it is the intent that counts. Try to accelerate the weight as fast as you can. If the third number is a 2 it should take the athlete 2 seconds to get the lift to the top, regardless of whether they are capable of moving it faster.
- The Fourth Number – The fourth number refers to the contracted position, and describes how long you should pause at the top of the lift. Take, for example, a weighted pull-up prescription of 20X2, the athlete would be expected to hold his or her chin over the bar for two seconds before beginning to come down. Tempo sets in a group setting are a great tool to utilise generally lighter weights but manipulate the outcome to achieve results and increase level of difficulty.
Isometric exercises are moves whereby you contract a muscle or muscle group and hold it in the same position for the duration of the exercise. It’s different from the movement patterns you typically use when strength training: concentric movements (tension on a muscle that’s shortening) or eccentric movements (tension on a muscle that’s lengthening).
The easiest example of an isometric move to think about is a plank. When you hold the plank position, you’re squeezing and engaging your entire core the whole time. That muscle contraction is called an isometric contraction.
A plank is just an isometric exercise, but many exercises actually incorporate all three movement patterns.
People forget that there’s an isometric action in almost every exercise. For example, in a squat, when you lower the weight down and your muscles lengthen, you’re in the eccentric phase. And when you push the weight back and your muscles contract, you’re in the concentric phrase. In between that, when you stop and pause at the bottom? That’s the isometric phase.
The same can apply to a biceps curl, if you add a hold to the move. When you bend your elbow and curl the weight up, that’s the concentric portion. When you straighten your elbow and lower the weight down, that’s the eccentric portion. If you paused halfway through and held the position at the top of the move, when your arm was at 90 degrees, that would be the isometric phase.
Other examples of isometric exercises include wall sits, calf raises, push up halfway holds and hollow-body holds. Holding any of your favourite non-isometric exercises in one specific spot—usually either the most challenging part of the exercise, or the moment just before you change direction—is also a simple way to add an isometric component to whatever you’re doing. (It’s also an easy way to make an exercise feel harder when you aren’t able to add additional weight to the move.)
Isometric exercises can help build strength, but in a slightly different way than concentric and eccentric movements do.
With concentric and eccentric exercises, especially on the eccentric part, the muscle fibre is being broken down. The resulting microscopic tears in the muscle will repair after exercise—which is why giving your body time to recover is so important—and ultimately end up building themselves up a little stronger than before.
But a large portion of the strength you gain doing isometric exercises comes from training your nervous system.
In general, with isometrics, you’re primarily training the nervous system to coordinate with your muscles in that specific position and fire the right muscles at the right time
This isn’t the most effective way to grow muscle, but it still helps you build or maintain strength.
Isometrics also train muscular endurance, or your ability to keep a muscle contracted for a long period of time.
This is what makes them great for improving stability. Think about your core: Doing a plank for an extended period of time trains your entire core to activate and stay strong and stable in this contracted position.
By working your core in this way, you’ll be able to fire all of the muscles and keep your body stable when you do other movements—think lunges or even running—that require your core to be engaged and sturdy too.