Influence of Long-Lasting Static Stretching Intervention on Functional and Morphological Parameters in the Plantar Flexors: A Randomized Controlled Trial

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Animal studies show that long-lasting stretching training can lead to significant hypertrophy and increases in maximal strength. Accordingly, previous human studies found significant improvements in maximal voluntary contraction (MVC), flexibility, and muscle thickness (MTh) using constant angle long-lasting stretching. It was hypothesized that long-lasting stretching with high intensity will lead to sufficient mechanical tension to induce muscle hypertrophy and maximal strength gains. This study examined muscle cross-sectional area (MCSA) using magnetic resonance imaging (MRI). Therefore, 45 well-trained subjects (f: 17, m: 28, age: 27.7 ± 3.0 years, height: 180.8 ± 4.9 cm, mass: 80.4 ± 7.2 kg) were assigned to an intervention group (IG) that stretched the plantar flexors 6 × 10 minutes per day for 6 weeks or a control group (CG). Data analysis was performed using 2-way ANOVA. There was a significant Time × Group interaction in MVC (p < 0.001-0.019, 2 = 0.158-0.223), flexibility (p < 0.001, 2 = 0.338-0.446), MTh (p = 0.002-0.013, 2 = 0.125-0.172), and MCSA (p = 0.003-0.014, 2 = 0.143-0.197). Post hoc analysis showed significant increases in MVC (d = 0.64-0.76), flexibility (d = 0.85-1.12), MTh (d = 0.53-0.6), and MCSA (d = 0.16-0.3) in IG compared with CG, thus confirming previous results in well-trained subjects. Furthermore, this study improved the quality for the morphological examination by investigating both heads of the gastrocnemius with MRI and sonography. Because stretching can be used passively, an application in rehabilitation settings seems plausible, especially if no commonly used alternatives such as strength training are applicable.

Original languageEnglish
JournalThe Journal of Strength and Conditioning Research
Issue number10
Pages (from-to)1993-2001
Number of pages9
Publication statusPublished - 01.10.2023

Bibliographical note

Funding Information:
The authors thank all subjects for their time and effort. Furthermore, performing the comparatively large number of MRI scans was only possible due to the high level of commitment of Gülsen Yanc. Many thanks for carrying out the MRI scans at all requested times of day. This work was supported by the Neuroimaging Unit of the Carl von Ossietzky Universität Oldenburg which is funded by grants from the German Research Foundation (3T MRI INST 184/152-1 FUGG). Data availability statement: Original data can be provided upon reasonable request. The authors report that there are no competing interests to declare. The researchers have no financial interests.

Publisher Copyright:
© 2023 NSCA National Strength and Conditioning Association. All rights reserved.

    Research areas

  • Physical education and sports - long-lasting stretching, maximal strength, maximal voluntary contraction, muscle cross-sectional area, muscle thickness, range of motion