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The Role of Stretching and Muscle Length in Hypertrophy

Muscle hypertrophy, the process of increasing muscle mass, is a primary goal for many fitness enthusiasts. While weightlifting and resistance training are well-known for promoting muscle hypertrophy, recent research highlights the significant role of stretching and training at longer muscle lengths.

This Muscle and Motion article delves into the relationship between stretching and hypertrophy, shedding light on how incorporating exercises that stretch the muscles may enhance muscle growth. 

Before diving into this article, we suggest reading our article, which provides a clear explanation of muscle hypertrophy. This will give you a solid foundation of understanding before you proceed.

 

The advantages of longer muscle length training

Recent studies have found that when you stretch your muscles more during exercise (like when doing a deep squat instead of a half squat), your muscles experience more metabolic stress. This kind of stress is actually good for muscle growth. It also increases a special growth-promoting substance in our bodies called Insulin-like Growth Factor 1 (IGF-1). Both this extra stress and the increase in IGF-1 are key factors that help muscles grow larger.[1,2]

 

 

This means that if you focus on exercises in which your muscles are more stretched out, you might see better muscle growth than if you do exercises where your muscles aren’t stretched as much. So, exercises that promote longer muscle length could be more effective for building bigger muscles.[3]

 

The evidence of longer muscle-length training

  • Biceps Brachii Study

Pedrosa et al. (2023) focused on the biceps brachii in 21 untrained women. Over eight weeks, each woman trained one arm, starting with the muscle stretched out (initial range of motion, Option A) and the other with less stretched muscle (final range of motion, Option B).[3]

The study found that the arm exercises starting with a more stretched muscle (Option A) led to more distal biceps brachii hypertrophy and a greater increase in overall arm strength. This was in comparison to the exercises where the muscles started less stretched (Option B). This suggests that exercises that begin with the muscles in a more elongated position might be more effective for increasing both muscle size and strength in the biceps.

 

 

  • Gastrocnemius Study

Kassiano et al. (2023) compared muscle thickness changes in the heads of the gastrocnemius when performing calf raises. They compared two methods: one where the calf muscles were stretched more (initial range of motion) and another where the muscles were stretched less (final range of motion). The findings revealed that initial range of motion training led to more significant increases in muscle thickness in both heads of the gastrocnemius, suggesting the superiority of training at longer muscle lengths for enhancing hypertrophy in the plantar flexors.[4]

 

 

  • Triceps Brachii Study

Maeo et al. (2023) investigated triceps brachii hypertrophy through MRI measurements. Participants were divided into two groups: one performing overhead triceps extensions (longer muscle length) and the other performing triceps push-down (shorter muscle length). The overhead extension group exhibited higher hypertrophy in all three heads of the triceps brachii, although no significant difference in 1RM was observed between the groups. This finding further supports the hypothesis that exercises at longer muscle lengths can lead to greater hypertrophy.[5]

 

 

These studies collectively demonstrate that exercises emphasizing longer muscle lengths can be more effective for muscle hypertrophy, applicable to both upper and lower body muscles. After we talked about the significant role of training at longer muscle lengths. Let’s review the literature about the effect of static stretching.

 

The role of static stretching in muscle hypertrophy

Static stretching involves holding a muscle in an elongated position for a set duration, typically contributing to increased flexibility. But what does the literature say about the effect of static stretching on hypertrophy? 

  • Plantar Flexors Study

Warneke et al. (2023) explored the impact of static stretching on the plantar flexors. The research involved 69 active participants who were divided into two groups: one undergoing static stretching and the other engaging in hypertrophy training. The study found significant improvements in maximal voluntary contraction, muscle thickness, and flexibility in both groups, with no notable differences. This suggests that static stretching can be as effective as traditional hypertrophy training in enhancing muscle strength and size.[6]

  • Pectoralis Major Study

Wohlann et al. (2024) focused on the pectoralis major muscle. The study involved 81 active participants and compared the effects of static stretching and resistance training on muscle strength, thickness, and flexibility. The results showed that static stretching led to increases in maximal strength and hypertrophy comparable to those achieved through resistance training. Additionally, the stretching group experienced a significant increase in flexibility.[7]

 

In summary, the research indicates that incorporating exercises that work the muscle at greater lengths, both dynamically and statically, can promote muscle strength and hypertrophy. Therefore, during your next workout, consider incorporating a static hold at the point where your muscles are fully extended. For instance, pause in the Pec Deck Fly in a static position when your chest muscles are fully stretched out (maximum shoulder horizontal abduction). This technique can help you increase your muscle gain.


 

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Reference:

  1. McMahon G, Morse CI, Burden A, Winwood K, Onambélé GL. Muscular adaptations and insulin-like growth factor-1 responses to resistance training are stretch-mediated: Length Modulates Adaptation. Muscle Nerve. 2014;49(1):108-119. doi:10.1002/mus.23884
  2. Pedrosa GF, Lima FV, Schoenfeld BJ, et al. Partial range of motion training elicits favorable improvements in muscular adaptations when carried out at long muscle lengths. EJSS (Champaign). 2022;22(8):1250-1260. doi:10.1080/17461391.2021.1927199
  3. Pedrosa GF, Simões MG, Figueiredo MOC, et al. Training in the initial range of motion promotes greater muscle adaptations than at final in the arm curl. Sports. 2023;11(2):39. doi:10.3390/sports11020039
  4. Kassiano W, Costa B, Kunevaliki G, et al. Greater gastrocnemius muscle hypertrophy after partial range of motion training performed at long muscle lengths. J Strength Cond Res. 2023;37(9):1746-1753. doi:10.1519/jsc.0000000000004460
  5. Maeo S, Wu Y, Huang M, et al. Triceps brachii hypertrophy is substantially greater after elbow extension training performed in the overhead versus neutral arm position. EJSS (Champaign). 2023;23(7):1240-1250. doi:10.1080/17461391.2022.2100279
  6. Warneke K, Wirth K, Keiner M, et al. Comparison of the effects of long-lasting static stretching and hypertrophy training on maximal strength, muscle thickness and flexibility in the plantar flexors. Eur J Appl Physiol. 2023;123(8):1773-1787. doi:10.1007/s00421-023-05184-6
  7. Wohlann T, Warneke K, Kalder V, Behm DG, Schmidt T, Schiemann S. Influence of 8-weeks of supervised static stretching or resistance training of pectoral major muscles on maximal strength, muscle thickness and range of motion. Eur J Appl Physiol. Published online 2024. doi:10.1007/s00421-023-05413-y
Uriah Turkel B.P.T
Uriah Turkel B.P.T
Uriah Turkel B.P.T, graduated from Ariel University School of Health Sciences, Physiotherapy Department. Uriah works as a content creator specialist at Muscle and Motion, his areas of expertise are anatomy, kinesiology, sports rehabilitation, gait analysis, rheumatology, and pain neuroscience. During his first degree, he conducted research on treatment methods for chronic ankle instability and the effects of Functional Electrical Stimulation (FES) on Peroneal Muscle Function in the Neuromuscular & Human Performance Lab. Currently, he is pursuing a Master of Science at the same lab, researching cognitive and gait decline during aging.