How-to: Mechanical Tension
TL; DR Version:
1) The ability to generate mechanical tension has the greatest impact on muscle gain.
2) A good proxy for generating sufficient mechanical tension is to bring a working muscle group to near failure (usually 1-2 repetitions before exhaustion).
a. This can be obtained through increased load, increased repetitions, improved mind-muscle connection, or some combination.
3) The mind-muscle connection is the ability to filter out synergistic muscle groups from specific exercises and primarily focus on intensely contracting desired muscles in isolation.
4) Generating mechanical tension through the mind-muscle connection is a life-long skill to develop.
We’ve previously introduced the idea that there are resistance training stimuli that actually trigger the muscle building adaptation when you’ve completed a workout. These were described as mechanical tension, metabolic stress, and muscle damage. While those are the underlying mechanistic triggers that occur while you lift weights during your training session – how do you know which to emphasize? How do you select exercise set, repetition, and loading schemes to prioritize each stimulus?
Mechanical tension has the greatest long-term benefit to any trainee. Learning how to direct a muscle contraction to only the desired muscle group during an exercise is paramount in maximizing your results. The “mind-muscle connection” is a long talked about topic that allows a trainee to slowly filter out unwanted “synergistic” muscle groups from helping lift a weight and only (maximally) contracting your preferred muscle group per exercise. For example, a cable pec fly is typically chosen to build a trainee’s chest, but inexperienced lifters may often feel quite a lot of work across the front shoulder muscle as well. Refining this skill is an ongoing process that tends to improve as the trainee gains experience – but naturally, trainees will want to experience early success as well; therefore, we must find other ways in early training to elicit a similar result as pure concentrated isolation that may take years to figure out.
In absence of sheer quality of exercise that is developed over a lifetime of training experience, there are a few methods to increase (note: increase, but not optimize) mechanical tension through intensification techniques that may cover the spread during the short-term.
First, adding weight to an exercise is one way to force more mechanical tension (muscle fibre recruitment / activation) from all active muscle groups in an exercise. While increasing the load will force the desired muscle to active more and more due to the increased demand of weight – the inexperienced trainee will also likely increase synergistic muscle group support as well. While not optimal for isolating only one muscle, it does help with early muscle gain. The “accidental” muscle engagement method. This idea is that there are only so many muscles that cause a certain limb to move (refer back to the pec fly exercise described earlier). If we increase the load, the pec itself will be forced to contract harder, but the front shoulder will also likely increase as well. While more engagement does likely mean more muscle gain – the result is more like a shotgun blast as opposed to a sniper shot.
Second, in absence of quality, overwhelming quantity. You typically see this approach in many online programs. The hallmark of the one-muscle-group-per-day style of training split. Assault your chosen muscle with an obscene number of sets and repetitions with modest weight until you have through sheer volume of exercise delivered enough stimuli for growth. The method behind the madness here is that the amount of work being performed by the single muscle group forces complete exhaustion of all (most) fibres due to restricted recovery time (rest between sets or exercises) and the fact that at some point all muscle fibres of the desired muscle group must be activated. This occurs not necessarily due to mind-muscle connection or intentional contraction intensity, but through sheer necessity. This can be great for early progress but also has a very short lifespan due to potential overuse injury, time restrictions, plateaus, and in all reality, boredom.
Another option is to commit to a few extended-sets per muscle group. In this case, mechanical tension is generated by extending what would normally be a set of 8-12 repetitions on a single exercise, to something to the order of 20+ repetitions. There are a few techniques, the most common of which would be a drop set. In the drop set, you would perform however many repetitions you are prescribed at the highest weight possible for the given exercise. From there, immediately drop the weight down by a reasonable amount that would allow you to keep going for another several repetitions. Repeat this process once, twice, or maybe even three times for the given exercise before being done the full drop set. The idea is that due to muscle damage, accumulated fatigue, or some combination, the decrease in performance at a certain weight can be offset by dropping the weight down and immediately continuing the set. Either the same active muscle fibres can continue to fatigue and be damaged further, or additional fibres are recruited to take on the task – thereby promoting more mechanical tension across the muscle.
These are just a few examples to get started with. The main goal of any trainee should be to refine the mind-muscle connection, and the ability to voluntarily, maximally, contract single muscle groups to optimize their training. As this skill improves, you may actually be able to reduce the weight of a given exercise and make greater progress due to the increased skill and directed muscle contraction. What ultimately links these techniques together is that all things being equal, generating mechanical tension is the process of bringing a desired muscle group close to failure. The inability to contract due to accumulated fatigue. You cannot simply go through the motions and expect progress because you completed the numbers written down in your program. In short, you will always have to work hard.
Best,
Eric