What is it…
The time your muscles spends under a load during a set and includes the concentric shortening phase, peak contraction phase, eccentric phase and stretch position phase.

It’s another way of calculating the total amount of work you perform during a workout and a key way to track your improvements in the gym. (i.e. when you can increase the weight used for a particular T.U.T.)

According to many experts in the field…
There are optimal time under tension (T.U.T.) for different training goals.
Strength and Force – 20 seconds or less
Hypertrophy – 30-70 seconds per set
Strength and Functional Hypertrophy – 30-50 seconds
Pure Hypertrophy – 50-70 seconds
Endurance – more than 70 seconds

Best ways to increase T.U.T. …
Slowed down negatives (3-4 seconds)
Focused peak contractions (2 seconds)
Held stretch position movements (2 seconds)
Higher reps performed explosively as long as possible (25 or more reps)
Partial reps after full rep failure is reached (another 5-10 reps)
Forced reps with spotter (another 2-5 reps)

Summary / Coach Notes
Time under tension is one of several pathways muscle growth….it is however not the only one. It is however frequently overlooked by many lifters and deserves more credit for it’s ability to stimulate growth and muscle development.

Completely abandoning lower rep, shorter duration sets is not the solution here, but remembering that TUT is one of the most important factors contributing to growth is the key. My advice is to use it frequently in your training regimen to take advantage of a proven mechanism to overload muscles.

Time under tension creates a great deal of metabolic stress and metabolic stress ranks at the top of factors that contribute to new muscle growth.

When hypertrophy is the goal, you should be almost always be looking for ways to subject your muscles to optimal time under tension ranges and ensure most sets last more than 30 seconds minimum.

Factoring in time under tension allows you to select the appropriate weights for each set. i.e. If you can only perform reps for 10 seconds with that weight, then it’s likely too heavy for you. In a way TUT prevents sloppy lifting technique and ego-driven sets.

If hypertrophy is NOT the goal (i.e. preventing a muscle from growing) then you will want to actually avoid the hypertrophy ranges and keep sets within 10-25 seconds in duration to keep a muscle from growing out of proportion.

Women may need longer TUT than men to build muscle due to gender differences in muscle metabolism. This is where their higher pain thresholds will be useful.

TUT helps to fully develop ALL types of muscle fibers including the slow twitch fibers. This is necessary for more complete, fuller development that shows better on a ripped physique.