Update:
While the importance of active tension toward muscle-building is correct here, passive tension also plays a unique role. Passive tension leads to longitudinal muscle growth along with more connective tissue. This often means including different exercises that focus on either active or passive tension for the target muscles.
Many poorly evaluate the factors leading to success in their lifting program. They focus on the burn in their muscles, the extent and duration of their soreness, the right sensation during a peak contraction, or other things that they deem important but that fail to drive real progress.
Tension is the main stimulus to develop muscle size and strength. Maximizing tension requires you to lift heavier and heavier weights, though not necessarily for low reps, however you can achieve it best. Choosing the right exercises along with maintaining good form will then let you reach this goal without harming yourself, while obtaining better results as well.
In regards to tension, we need to be more specific though. It has two forms: active and passive. Active tension is what causes muscle growth. Evidence though seems to show that the release of energy stored through passive tension will not just improve performance but enhance active tension.
Active tension comes from the contraction of your muscles after receiving a signal from the nervous system. Filaments within your muscles, known as myosin and actin, bind together to form cross-bridges. This process, especially in the fast-twitch fibers, tells your body to build more size and strength.
Passive tension comes through the resistance to stretching that your muscles possess, creating stiffness through proteins such as titin and other connective tissue. These parts allow your muscles to elongate and then return to their resting state.
Further analyzing active and passive tension reveal these helpful insights.
Insights
If everyone is thinking alike, then somebody isn’t thinking.
– George S. Patton
- A deep stretch increases passive tension but limits active tension.
Many mistakenly associate a deep stretch, which increases passive tension, with a more intense contraction. If touching the muscles when stretched, you would notice they feel taut, which can mislead you. Two popular exercises make this misconception clear: the stiff-legged dead-lift and the overhead triceps extension.
On the stiff-legged dead-lift, the hamstrings will feel tight at the bottom since they stretch over the hip and knee joints. When contracting from this position though, active tension is low, since many filaments fail to reach each other for a connection. Should you fail the rep here, you will have ended the exercise in a position that limited active tension.
On the overhead triceps extension, the long head of the triceps lengthens over both the shoulder and the elbow. This has the same effect: you have higher passive tension and lower active tension.
These two exercises can harm you otherwise as well. The lower back can get injured easily on the stiff-legged deadlift along with irritating the hips or tearing the hamstrings. The overhead triceps extension stresses both the shoulder and the elbow due to its awkward position.
The hamstrings work sufficiently on a squat with the correct low-bar position. The long head of the triceps works more intensely on a pull like the row instead of a bench press, since this muscle head is placed further from the shoulder than the elbow.
Avoid a deep stretch on any exercise when lifting. Besides reducing active tension, it can reduce blood flow and lead to less strength available in better positions.
- Active tension is greatest at the midpoint.
Active tension is greatest in the muscles at about the midpoint of a joint’s fullest possible range of motion. The filaments within your muscles that bind together to create tension overlap best here. The length-tension relationship makes this clear.
On good exercises, this occurs when leverage is worst and where you feel weakest. On the bench press, this happens when your elbows are furthest away from your body, or with your hips and knees furthest away from the barbell on the squat.
This position of poor leverage, yet ideal active tension, is one with barely any passive tension. It shows that many use much more range of motion than they need.
When research states that a muscle with a resting length of 110-120%, a slightly stretched position, generates the highest tension, keep in mind that this means for both total tension. Active tension dips away from the midpoint.
- Some passive tension may boost active tension.
We know for sure that a stretch improves the outward expression of strength by improving the force of a concentric contraction. Imagine trying to jump as high as possible. You drop your hips and arms a bit and then quickly transition to explode into the air.
Consider that if a great stretch helped much, then you would descend lower before springing into the air. Though the difference is subtle, this actually deals with two separate issues:
- A muscle lengthening over any position throughout the range of motion allows for a stretch-shortening cycle, which can then release as elastic energy with a quick transition during positive movement. Also, it seems that this stretch reflex may improve active tension itself.
- Slight passive tension builds up depending on getting enough of a stretch through the range of motion.
It seems then that both a quick transition and enough range of motion allows the most passive tension to form and then convert as elastic energy. Though done more slowly, this applies to lifting weights too, not just explosive movements like sprinting and jumping.
Moving too slowly and without enough range of motion will limit passive tension. Going too quickly though dissipates much of this energy while threatening your safety since you lose control.
For the range of motion, you only need a slight stretch as well, not the most possible.
Insights from Active vs. Passive Tension
Your main goal in lifting should be to maximize active tension. Some passive tension though, both through enough range of motion and a quick but smooth transition from lowering to lifting, will improve your performance. This seems to help in other ways beyond the discussion here too.
You should avoid exercises in which you feel a deep stretch in the muscles. You should not need to go too far beyond the midpoint for a good exercise, which includes the bench press, the squat, and the row. You also need to avoid moving too fast as to lose control.
I understand that being more exact is helpful, though it is hard to define this precisely. For speed, most trainees do well with at least a second or two for lowering the weight and then lifting it as fast as possible without jerking the weight. For the range of motion, you can go as far as needed past the midpoint so that you feel a slight stretch while having enough space to generate power and get in a groove, yet that prevents any joint pain or discomfort. The endpoints should exist closer to the midpoint than the extremes for joints’ range of motion, though a lockout position works fine.
Heed this advice from these insights, though just as importantly, choose the right exercises, while getting stronger and more muscular by adding weight in good form. This will allow your training to be optimal.