I’ve mentioned rest breaks before as a great way to increase the intensity of workouts and a way to manipulate them depending on your goals. Another method is the tempo at which you do exercises. The slower you move through each phase of an exercise, the more strain is placed on the muscle(s). This is called time under tension, or TUT.
There are 4 phases to most exercises:
Eccentric: When the weight is lowered, the descent portion of a squat or when you’re lowering the bar to your chest during presses, for example.
Stretched: This is when the muscle is fully stretched. Using the same examples as above, in a squat it is at the very bottom of the movement and on during presses it’s when the bar is making contact with your chest.
Concentric: The opposite of the eccentric portion. This is when the muscle is shortening during an exercise.
Contracted: When the muscle is totally contracted, the top of a squat, or when your arms are locked out during presses.
Unfortunately, most routines and trainers/coaches ignore or otherwise do not utilize TUT, the eccentric phase being very important for developing strength. Though mostly anecdotal evidence (as most cutting edge exercise science is) it is generally accepted that there are TUT ranges for specific goals, just as there are rest periods. To maximize strength, between 5 and 20 seconds; for size the optimal range is 40-60 seconds; endurance training is best between 70 and 100 seconds. Keep in mind these times are for a set. For example, a set of 10 curls done at 4 seconds per rep would be 40 seconds, within the optimal range for size/mass gains.
So next time you’re in the gym, along with keeping track of how long your rest between sets, also be aware of how long each rep is taking to do. Tempo/TUT is a very important and useful factor in any training program.