The term “Time-under-tension” (TUT) is really hot in the bodybuilding, athletic consulting, and fitness industries. It refers to the amount of time per rep (or set, or exercise, or workout) that the muscle is under tension. For example, if an athlete takes 4 seconds to perform a biceps curl, it is said that the TUT was 4 seconds. If someone performs 100 repetitions, then the workout TUT was 6 minutes and 40 seconds.

Many people want to know, “What is the best TUT for growth?”

A really good question, but unfortunately, you will not find any peer-reviewed research on the optimal time under tension. All TUT claims are merely anecdotal and have simply been promoted by popular strength coaches,

leading to this belief. At present, no one, not even the most experienced exercise physiologist truly can prove what is the optimal TUT for growth, let alone prove the exact mechanism that controls muscle hypertrophy. Is it training to failure, an optimal TUT, an optimal resistance, or a specific number of reps that gives you the greatest muscle growth from training?

Unfortunately, none of the TUT schemes, nor any other bodybuilding method, has been proven to be more effective than others in a research setting. Muscle growth is merely an adaptation to the correct intensity and volume of work. Your muscle responds to the demand (training) by adapting (growing) so that the next time you ask your muscle to lift

that same weight, it will have an easier time doing so. Almost all programs will work, and that is why anyone and everyone can write training articles, provided it has some common sense behind.

However, having said all that, strength coaches, bodybuilders, and researchers are obviously on the right track with TUT philosophies. Muscle tension is undoubtedly one of the most important factors in muscle growth. After all, if you train too lightly and with too many reps, your body will adapt by increasing endurance properties…and muscle growth may actually be the last thing your body will do in preparation for the next training session. Basically, this is why endurance exercise doesn’t cause growth. Muscle doesn’t need to get bigger

to have better endurance.

Using extremely heavy weights that allow only 1-2 repetitions per set or performing a few explosive repetitions may not provide enough tension for muscle growth. Therefore, if muscle mass is your goal, sets lasting only 5-10 seconds are probably not going to be optimal for gains. On the other hand, you don’t want to go too light, because performing 100 reps with the 5 lb dumbbells is not likely to prove effective either, even though this represents a huge TUT.

DO YOUR MUSCLES EVEN DIFFERENTIATE BETWEEN TUT & REPS?

The answer is probably no, your muscles don’t distinguish between time under tension or the number of reps. Muscles simply respond to the demands imposed on the

body. If the exercise demands the muscle to grow bigger in preparation for the next session, then that is what will happen, regardless of exercise choice.

The fact is that a lot of guys go in the gym, lift hard, and get big without giving the slightest thought to TUT. General recommendations for “hypertrophy training” are 8-12 reps per set, with multiple sets per exercise, and multiple exercises per body part. The debate over the best training program is endless. What is the optimal training frequency? How often should you train a body part?

The number of training questions is infinite, as the precise knowledge is limited, despite the success of top-level bodybuilders and athletes. The lack of uncertainty regarding

TUT and almost all training parameters gives good anecdotal evidence that people should constantly be varying their programs (after 3-4 weeks or when gains begin to slow down or disappear). Don’t get hung up on one specific TUT. You can get growth on sets shorter and longer than just one specific time period.

So, there are no scientific conclusions, only theories. You are better off seeking research that shows significant muscle growth with a certain number of reps, and then extrapolate a TUT…because you will find very little, if any, science that controls the speed of repetition. However, even repetition data is scarce.

On a related note, you must remember not to look at TUT as an isolated factor in

growth…You can train in the perfect rep range with the perfect intensity, but if you neglect adequate nutrition (i.e. a calorie surplus), then you can forget about growing. In contrast, if you eat 5000kcal a day, you will grow no matter how you train. Same with rest…you shouldn’t neglect it.

In closing, think of muscle growth this way…does the construction worker worry about “Time under tension”? NO! He simply carries as many bricks as he can handle. Then next week, after he has grown bigger and stronger, he carries more bricks…week in and week out…plus he eats big. According to Men’s Health consultant Michael Mejia, “The bottom line is that there is TONS of great information out there, but often

we make this stuff out to be rocket science when it really isn’t.”

Craig Ballantyne is a Certified Strength & Conditioning Specialist and writes for Men’s Health, Men’s Fitness, Maximum Fitness, Muscle and Fitness Hers, and Oxygen magazines. His trademarked Turbulence Training fat loss workouts have been featured multiple times in Men s Fitness and Maximum Fitness magazines, and have helped thousands of men and women around the world lose fat, gain muscle, and get lean in less than 45 minutes three times per week. For more information on the Turbulence Training workouts that will help you burn fat without long, slow cardio sessions or fancy equipment, visit http://www.TurbulenceTraining.com