DOES STRETCHING HELP MUSCLE GROWTH? A NEW SAYS YES

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DOES STRETCHING HELP MUSCLE GROWTH SUMMARY

• Some but not all studies have found that weighted stretching between sets can increase muscle growth.
• Recent studies have shown that training a muscle in a stretched position can lead to greater increases in muscle growth than training with a full range of motion
• Stretch the calf muscle for an hour a day for six weeks resulted in muscle hypertrophy by 15.2% 2.1% in the unstretched calf

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10/20 RESEARCH UPDATE: WEIGHTED STRETCHING FOR MUSCLE GROWTH BETWEEN SETS

Lengthening the muscle provides an anabolic stimulus for muscle growth. Static stretching alone between sets for 30 seconds has been found to increase muscle growth compared to passive resting between sets.(1) The study found that the summed increases in muscle thickness for muscles of the upper and lower limbs were greater for a group of untrained individuals who performed a 30-second inter-set unloaded static stretching regimen versus a group that rested passively between sets (10.5% vs. 6.7%, respectively).

The article below found that six weeks of isolated stretching of the calf muscle resulted in increased muscle growth compared to the unstretched muscle.(6) Others have found that weighted stretching between sets (i.e., stretching the muscle with weights) can enhance muscle growth compared to passive resting between sets.(2)

RESEARCH

Silva et al. also found that weighted calf stretches between sets resulted in more muscle growth than those that rested passively between sets.(3) The research suggests that weighted lengthening of the muscle may result in more muscle growth, but not all studies have found that weighted stretching enhances muscle growth.(4) Wadhi et al. found no differences in muscle growth of the chest with loaded weight stretches compared to those that just rested between sets. The amount of weight used in (i.e., 15% of the working set) the Wadhi et al. study may not have been heavy enough to provide an anabolic stimulus to increase muscle growth.

2014 abstract suggested that weighted lengthening of the muscle between sets can enhance muscle growth of the calves (i.e., gastrocnemius).(5) Researchers decided to re-study the use of weighted stretching between sets to determine if weighted stretching can increase the muscle growth of the calves. 25 untrained, recreationally active students were assigned to calf raises either performed regularly with weights or weights plus inter-set stretching with weights for eight weeks.

The subjects performed straight, and seated calf raises performed twice per week. The resistance exercise protocol comprised four sets with 8-12 reps with two minutes rest between sets and three minutes rest between exercises. The only difference between the groups was that the inter-set stretch group used the same weight they used during sets and stretched the calves for 20 seconds.

All subjects were trained to muscular failure, and the weight was adjusted each week to target a resistance exercise weight that subjects could perform 8-12 reps. The researchers measured the muscle thickness of the calves in all the muscle groups (i.e., lateral gastrocnemius, medial gastrocnemius, and soleus).

RESULTS

The researchers found a small effect on muscle strength of weighted stretching between sets. No one cares about calf strength; everybody doing calf raises wants to see muscle growth, right? The results were inconclusive in that weighted stretching between sets can enhance muscle growth. The lateral and medial parts of the calf did not grow more with weighted calf stretching. However, the soleus muscle had greater increases in muscle growth with weighted stretching between sets. The researchers suggested the soleus is a type I muscle (>80%) fiber and is heavily used in normal activities such as walking and standing.

TENSION

The greater time under tension placed on the soleus with weighted stretches between sets may have contributed to greater muscle growth. The soleus muscle is more resistant to anabolic signaling and protein synthesis than the gastrocnemius.(6, 7)  The gastrocnemius is a similar combination of type I and II fibers.

The study is not a clear win for performing weighted calf stretches between sets, but it suggests that performing the exercises will cause muscle growth of the soleus, making the calf muscle look bigger. Weighted calf stretches are probably beneficial to perform between sets compared to passively resting, as it results in additional muscle growth of the soleus muscle.

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DOES STRETCHING ALONE BUILD MUSCLE?

Not all bodybuilders are blessed with great calves. Calves can often be a hard bodypart to grow for many lifters due to the high number of type I fibers in the soleus and gastrocnemius muscle. One of the most common mistakes often made in training the calves is a lack of range of motion while performing calf exercises.

Many lifters will load up the rack but do not use a complete stretch while training the calves. They tend to bounce up and down, performing partial reps for the calves. Lengthening of the muscle has been shown to result in greater muscle growth. Recent studies have shown that training a muscle in a stretched position can lead to greater increases in muscle growth than training with a full range of motion.(1-3)

Seated hamstring curls lead to more hamstring growth than lying leg curls due to increased muscle stretch. (1) Bottom-stretched preacher curls yield more muscle growth than top-portion curls. (2) A recent study indicates daily hour-long muscle stretching can boost muscle size without weights.

Most lifters neglect stretching, but a few studies show that adding deep stretches to your routine can increase muscle growth. A study on volleyball players found that stretching increased muscle thickness by 23% compared to a control group.(4)  Others have found that stretching for 3 minutes a day increased muscle size by 5.6%.(5) However, not all studies have found that lengthening of the muscle can increase muscle growth. The discrepancies in the studies may be because of the differences in the duration, frequency, and intensity of the muscle stretch.

WHAT HAPPENS IF YOU STRETCH FOR AN HOUR A DAY?

Researchers had subjects stretch their calf muscle for an hour a day for six weeks, while the other calf served as a control group with no stretch. The stretching group used an orthosis device, which places the calf muscle on stretch. See the picture below.

To achieve high intensity and muscle tension during the lengthening of the muscle training, subjects were asked to reach a maximal dorsiflexed position with an individual stretching pain at eight on a scale of 1 to 10. The subjects performed this stretch seven days a week. The researchers measured muscle growth and strength test before and after six weeks of stretching. The subjects continued their regular activity throughout the day.

After 6 weeks of stretching, the results were:

•       Maximal isometric strength increased by 16.8%
•       Maximal dynamic strength increased by 25.1% versus 11.4% in the unstretched calf muscle.
•       Muscle hypertrophy increased by 15.2% in the 1-hour stretching leg versus 2.1% in the unstretched calf.(6)

CHANGES IN MUSCLE THICKNESS 

Warneke, Konstantin & Brinkmann, Anna & Hillebrecht, Martin & Schiemann, Stephan. (2022). Influence of Long-Lasting Static Stretchhing on Maximal Strength, Muscle Thickness and Flexibility. Frontiers in Physiology. 13. 10.3389/fphys.2022.878955.

For lifters aiming to enhance calf size, a daily hour-long muscle stretch at home, even during TV time, can be effective. Notably, subjects felt a pain intensity of 8/10 during this stretching routine.

Of the studies that did not find increases in muscle growth, many did not quantify the intensity of the stretch. Many studies utilized a brief muscle lengthening duration, often 5 minutes or less. Studies that didn’t report muscle growth typically had a lower frequency, around 2 days per week.

 

REFERENCES

1.         Maeo S, Huang M, Wu Y, Sakurai H, Kusagawa Y, Sugiyama T, et al. Greater Hamstrings Muscle Hypertrophy but Similar Damage Protection after Training at Long versus Short Muscle Lengths. Med Sci Sports Exerc. 2021;53(4):825-37.

2.         Sato S, Yoshida R, Kiyono R, Yahata K, Yasaka K, Nunes JP, et al. Elbow Joint Angles in Elbow Flexor Unilateral Resistance Exercise Training Determine Its Effects on Muscle Strength and Thickness of Trained and Non-trained Arms. Frontiers in Physiology. 2021;12.

3.         Oranchuk DJ, Storey AG, Nelson AR, Cronin JB. Isometric training and long-term adaptations: Effects of muscle length, intensity, and intent: A systematic review. Scand J Med Sci Sports. 2019;29(4):484-503.

4.         Panidi I, Bogdanis GC, Terzis G, Donti A, Konrad A, Gaspari V, et al. Muscle Architectural and Functional Adaptations Following 12-Weeks of Stretching in Adolescent Female Athletes. Frontiers in Physiology. 2021;12.

5.         Simpson CL, Kim BDH, Bourcet MR, Jones GR, Jakobi JM. Stretch training induces unequal adaptation in muscle fascicles and thickness in medial and lateral gastrocnemii. Scand J Med Sci Sports. 2017;27(12):1597-604.

6.         Warneke K, Brinkmann A, Hillebrecht M, Schiemann S. Influence of Long-Lasting Static Stretching on Maximal Strength, Muscle Thickness and Flexibility. Frontiers in Physiology. 2022;13.

7.         Yahata K, Konrad A, Sato S, Kiyono R, Yoshida R, Fukaya T, et al. Effects of a high-volume static stretching programme on plantar-flexor muscle strength and architecture. Eur J Appl Physiol. 2021;121(4):1159-66.

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