When muscles grow, they do so through one of two mechanisms: either by making existing muscle fibers bigger, or through the addition of new muscle fibers.
Recent research was primarily centered on the second method, which is known as hyperplasia.
While the first method of growth is more or less uniformly known and accepted by scientists, the second method has been more controversial. There are two proposed mechanisms through which individuals achieve hyperplasia, or add new muscle fibers. The first mechanism is when existing muscle fibers split. The second is when your body activates specialized cells known as satellite cells.
The satellite cells then divide and combine to form new muscle fibers. Both of these methods require extreme mechanical stress and damage to induce hyperplasia.
Unfortunately, our ability to detect changes in muscle fibers in humans is quite difficult because we can’t count the number of fibers from pre- to post-training in an entire muscle group. Unlike an animal model where it is possible to count every single muscle fiber, you have to make assumptions from a small muscle sample in humans. However, indirect methods in humans still point toward hyperplasia.One of the best studies on this topic to date was performed by Dr. Tesch and Dr. Larsson back in 1982.3 These scientists found that many of the muscle fibers in highly trained bodybuilders were the exact same size as recreationally trained physical-education students. The fact that the bodybuilders had much larger muscle mass indicated that many of their muscle fibers had been newly created.
So should you duct-tape some weight plates to your arms for the next month? I wouldn’t.
Until recently, no human studies had been performed to investigate muscle growth with intermittent stretching protocols. However, two new studies have shown that intense stretching—even without lifting weights—increased strength by greater than 20 percent in only 3-8 weeks.5,6 Because individuals weren’t actually lifting weights, an increase in strength strongly suggests—and other research supports—that the muscle must be enlarging, either by increasing fiber size or quantity.
Our lab recently tried to tie together all the existing research into a training protocol that bodybuilders could use right away. Our study, led by Jacob Rauch and Jeremy Silva, focused on individuals performing seated calf presses on the leg press.
The athletes began with a weight they could lift 12-15 times until failure. However, instead of resting between sets, they let the weight from the leg press stretch their calves for 30 seconds. They repeated this process three times, dropping the weight after each stretch.
After 5 weeks we found that the stretching group doubled the muscle gains of the non-stretching group! Here’s what we now believe to be the case:
- The key to stretch-induced growth is to create both a large amount of mechanical tension and muscle damage.
- The stretch placed upon a muscle fiber seems to be greatest after an individual has achieved significant cell swelling, or pump.
After this swelling has been increased, we believe that intermittent stretching would have its greatest chance to work.
PUTTING IT TO WORK FOR YOU
As you can imagine, stretching is a part of a normal lift. Specifically, exercises which place a muscle in its extreme range of motion—such as incline dumbbell curls for the biceps—increase mechanical strain, and thus, hypertrophy.7
However, based on the evidence above, it seems clear to us that some amount of weighted intermittent stretching is even more effective at increasing muscle growth, even in muscle groups as stubborn as the calves.
But a quick warning: I guarantee that this will be one of the most challenging techniques you have ever implemented, and the pump will be like nothing you’ve ever experienced!
For this reason, it’s crucial that you only perform this technique with exercises where you can stretch the muscle without putting yourself at risk of injury. For example, don’t use dips to stretch your pecs, because your shoulders would be placed in a dangerous position. Instead, try something like lying dumbbell flyes, where you hold the weight in the stretched portion of the lift.
For a one-month specialization program, I suggest performing a variation on the routine below twice a week. Use a weight you can lift for 12-15 repetitions. When you reach failure, let the weight stretch your muscles. At this point, perform a dropset where you strip the weight down by 15 percent and go to failure again. Repeat this process 2-3 more times, and you’ll be—and feel—done.
Here’s how you could use it for specific body parts, and a full month-long specialization routine for the calves.
- Biceps: Between sets of standing or incline seated dumbbell curls, let the weight pull you into controlled hyperextension at the shoulder, maximizing stretch and tension on the biceps.
- Chest: Between sets of chest flyes, allow the weight to stretch your chest while maintaining a slight bend in the elbows.
- Traps: Following a set a shrugs, allow the weight to keep you in a depressed position without letting the weight rest against your sides.
- Hamstrings: Between sets of Romanian deadlifts, emphasize the bottom position. Extend your hips back as far as you can with your weight on your heels for maximum tension on the hamstrings. Keep the weight as close to your body as possible.
- Quads: Between any quad exercise, perform the classic quad stretch. Sit on the backs of your heels and place your hands behind you. Depending on your level of flexibility, you can walk your hands back for increased stretch.
- Back: After completing a set of pull-ups, fully extend your arms and hang. Keep your feet off the ground for maximal tension.
- Triceps: Between sets of triceps rope extensions, let the rope pull you back into a stretched position.