Tension Mechanics

Research carried out by a sports scientist (Nicholas Burd), could well change the way we train.Tense muscle time" (TST), or more colloquially "slow reps", seems to be becoming a familiar concept in the weight room.

In 2010, the subject of Nicholas Burd's studies concerned athletes who had trained with just 30% of their maximum load - doing sets of 20 to 30 repetitions - and yet had synthesized more muscle protein than athletes who had trained in the conventional way.

Lifting load not the main factor

The theory of the scientists - who were studying strength training at the time - was that load was not the most important factor, or at least, not a primary factor for better progress.

An equally important factor was "muscle time under tension" (MHT), i.e. the length of time the muscles were under tension during exercise. In other words, the total duration of exercise execution time (concentric and eccentric phases).

The results of this latest study, published in The Journal of Physiology, clearly demonstrate that slower repetitions are more effective at stimulating muscle growth.

The more muscle fibers are subjected to tension, the more they break down. In response, the body will dramatically increase protein synthesis to rebuild the muscle and fibers broken during the session.

You will undoubtedly realize that if you were to compare two sets, one "TST" and the other "classic", the load used will be reduced, so you'll have to leave your ego at home and concentrate on sensations, which will have much more useful physiological parameters for gaining mass or strength, depending on your objectives.

The table above shows how training with slow repetitions leads to improved muscle protein synthesis.

Time under tension and muscle growth

As mentioned above, training with slow repetitions leads to greater muscle protein synthesis (the researchers noticed this when they examined the cells they extracted from the athletes' muscles during the experiment).

This is true for contracting myofibrillar protein (the protein found in muscle fibers) and mitochondrial protein (the proteins found in mitochondria).

The latter suggests that training with slow repetitions could also be of interest to endurance athletes.

Electrode measurements show that the sets induced greater recruitment of muscle fibers during exercise. These results suggest that the time the muscle is under tension during exercise may be important for optimizing muscle growth.

This insight makes it possible to propose appropriate exercises to those wishing to build more massive muscles and prevent the loss of muscle mass.

Practical conclusions and training

Some athletes suggest that slowing down reps is a way of limiting progression, while others maintain that TST is effective. Whatever the case, the TST "technique" is increasingly proving its worth in the bodybuilding world, and the science is proving it too.

Nonetheless, as every bodybuilder is different, the best thing to do is to listen to your body, and stick with your training as long as it delivers good results. TST can be a solution if you're looking for new sensations.

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Source: - The slower your reps, the more your muscles grow 
 - J Physiol. 2011 Nov 21.  [Epub ahead of print]