Muscle Architectural and Functional Adaptations Following 12-Weeks of Stretching in Adolescent Female Athletes.

Ioli Panidi,Vasiliki Gaspari,Gregory C Bogdanis,Anastasia Donti,Gerasimos Terzis,Andreas Konrad,Olyvia Donti

doi:10.3389/fphys.2021.701338

Ioli Panidi, Vasiliki Gaspari + Show 5 more

Open Access

https://doi.org/10.3389/fphys.2021.701338

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Abstract

This study examined the effects of high-volume static stretching training on gastrocnemius muscle architecture, ankle angle and jump height in 21 female adolescent volleyball players. Static stretching of the plantar flexors of one leg (STR) was performed five times/week for 12 weeks, in addition to volleyball training, with the contra-lateral leg used as control (CON). Total duration of stretching per session increased from 540 s (week 1) to 900 s (week 12). At baseline, week 12 and after 3 weeks of detraining, muscle architecture at the middle and the distal part of both gastrocnemius heads (medialis and lateralis) and ankle angle were examined at rest and at maximum dorsiflexion. At the same time-points gastrocnemius cross-sectional area (CSA) was also assessed, while jumping height was measured at baseline and week 12. Following intervention, ankle dorsiflexion increased in both legs with a greater increase in STR than CON (22 ± 20% vs. 8 ± 17%, p < 0.001). Fascicle length at the middle part of gastrocnemius medialis increased only in the STR, at rest (6 ± 7%, p = 0.006) and at maximum dorsiflexion (11 ± 7%, p < 0.001). Fascicle length at maximum dorsiflexion also increased at the distal part of gastrocnemius lateralis of STR (15 ± 13%, p < 0.001). A greater increase in CSA (23 ± 14% vs. 13 ± 14%, p < 0.001) and in one-leg jumping height (27 ± 30% vs. 17 ± 23%, p < 0.001) was found in STR than CON. Changes in ankle angle, fascicle length and CSA were maintained following detraining. High-volume stretching training for 12 weeks results in ankle dorsiflexion, fascicle length and muscle cross sectional area increases in adolescent female volleyball players. These adaptations may partly explain improvements in jump performance.

Highlights

Skeletal muscle tissue remodels its structure in response to mechanical loading, growth (Bénard et al, 2011) and type of muscle contraction (Franchi et al, 2017)
intra-class correlation coefficient (ICC) for fascicle length was 0.971, for pennation angle was 0.897 and for thickness was 0.868
Post-hoc comparisons showed that resting ankle angle increased from pre- to postintervention (p < 0.001) in both legs, with no difference between legs (p = 1.000), and this improvement was maintained during detraining (p = 1.000)

Summary

Introduction

Skeletal muscle tissue remodels its structure in response to mechanical loading, growth (Bénard et al, 2011) and type of muscle contraction (Franchi et al, 2017). Some studies found significant increases in fascicle length (Freitas and Mil-Homens, 2015; Simpson et al, 2017; Andrade et al, 2020) following 6–12 weeks of stretching training, while there is evidence that morphological changes are heterogeneous across muscle length or between muscles (Simpson et al, 2017). Longer-term stretching interventions (Andrade et al, 2020), overloaded static stretching (Simpson et al, 2017) and/or high-intensity and long-duration stretching bouts (Freitas and Mil-Homens, 2015) were more effective in triggering morphological adaptations in the muscletendon unit

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