Should We Strive For A Signature Time Under Load? by Matthew Romans

Most Total Results clients and regular readers of our blog posts know that for every exercise of every workout (except for negative-only or manually resisted exercises) we record a client's time under load (TUL). TUL is a measure of how long your muscles are under tension and contracting against a meaningful resistance. We find that this is generally more effective than recording the number of repetitions completed, since counting repetitions is a step function. You might complete six repetitions in good form and get halfway toward finishing a seventh before reaching momentary muscular failure (MMF); if you count repetitions there will be no credit given for the effort that you made on that final repetition that was not completed, but if you record TUL that extra time spent will be included. We select a resistance that should enable the client to reach MMF between one and three minutes of TUL, and if failure is not achieved in that time frame we will arbitrarily stop the exercise and make a note to increase the weight for the next workout.

I am often asked by clients if there is a specific TUL that they should look to achieve, or if there is such a thing as a signature TUL. This idea theorizes that clients should or will achieve the same or similar TUL on each exercise of their workout, with one of the contributing factors being muscle fiber type. Dr. Doug McGuff, the owner of Ultimate Exercise (a studio very much like Total Results) in Seneca, South Carolina, wrote about this concept many years ago in his collection of articles "Ultimate Exercise - Bulletin Number One." Based on what we had read from Dr. McGuff and a few other sources, we looked to find a signature TUL in our clients and figured that if exercise frequency, intensity, and volume were standardized and if recovery, nutrition, and hydration were adequate that we would find a signature TUL that would enable the client to linearly progress in resistance.

It didn't take long to figure out that we were mostly wrong. I have found that a signature TUL rarely happens with most trainees, including myself. TUL can vary from one person to the next, and even for the same person it can be wildly different from one exercise to another. As I mentioned above, exercise frequency, volume, and intensity, as well as nutrition and hydration will have an impact on TUL, but there are other factors as well. Mental focus, the ability to handle exertional discomfort (burning), sleep, and how much additional activity you participate in will also have an effect on your performance. If you have slept poorly for a few days due to stress or too much caffeine, or if you played three hours of tennis just prior to your workout, there is a good chance that your TUL on the Leg Press exercise will probably be shorter than usual.

The primary exercise objective is to inroad (fatigue) the muscular structures deeply enough to stimulate body improvements in the forms of strength, cardiovascular and metabolic conditioning, bone density, insulin sensitivity, an improved immune system, and protection against injury. We want to reach muscular failure between one and three minutes of elapsed time because this ensures that we are adequately tapping into the aerobic and anaerobic metabolic pathways; too short of a TUL means the weight is too heavy and the injury risk increases, and too long of a TUL means that the resistance is not meaningful enough to stimulate the growth mechanism. TUL is a good guideline to use, but it's merely one factor that measures progress. Pace and speed of movement matter, and if we do not meet our standard for speed (8-12 seconds in each direction) then TUL can get skewed and muscular loading can be less than optimal. The sequence of exercises performed in a workout can also affect TUL; if you normally perform the Leg Press second in your exercise routine but one day perform it as your last exercise, you will get a dramatically different result. To ensure accurate record-keeping, we would like to have as few variables as possible. The majority of our experienced clients tend to have a TUL on most exercises between 1:30 and 2:00.

Don't be overly concerned with achieving a certain TUL. Remember, your main objective is to create an exercise stimulus, not complete an arbitrary number of repetitions. Instead of worrying about how many repetitions you get, focus your attention on breathing properly, moving smoothly, and executing precise turnarounds. I would rather see a client perform 5 perfect repetitions with a thorough inroad at the end of the exercise than for them to complete 7 repetitions in poor form. Giving great effort and using perfect form are far more important than reaching a specific TUL.