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Birat A, Garnier YM, Dupuy A, Bontemps B, Dodu A, Grossoeuvre C, Dupont AC, Rance M, Morel C, Blazevich AJ, Nottin S, Ratel S. Neuromuscular Adaptations in Endurance-Trained Male Adolescents Versus Untrained Peers: A 9-Month Longitudinal Study. Scand J Med Sci Sports 2024; 34:e14681. [PMID: 38881390 DOI: 10.1111/sms.14681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2024] [Revised: 05/30/2024] [Accepted: 05/31/2024] [Indexed: 06/18/2024]
Abstract
BACKGROUND Neuromuscular function is considered as a determinant factor of endurance performance during adulthood. However, whether endurance training triggers further neuromuscular adaptations exceeding those of growth and maturation alone over the rapid adolescent growth period is yet to be determined. OBJECTIVE The present study investigated the concurrent role of growth, maturation, and endurance training on neuromuscular function through a 9-month training period in adolescent triathletes. METHODS Thirty-eight 13- to 15-year-old males (23 triathletes [~6 h/week endurance training] and 15 untrained [<2 h/week endurance activity]) were evaluated before and after a 9-month triathlon training season. Maximal oxygen uptake (V̇O2max) and power at V̇O2max were assessed during incremental cycling. Knee extensor maximal voluntary isometric contraction torque (MVCISO) was measured and the voluntary activation level (VAL) was determined using the twitch interpolation technique. Knee extensor doublet peak torque (T100Hz) and normalized vastus lateralis (VL) electromyographic activity (EMG/M-wave) were also determined. VL and rectus femoris (RF) muscle architecture was assessed using ultrasonography. RESULTS Absolute V̇O2max increased similarly in both groups but power at V̇O2max only significantly increased in triathletes (+13.8%). MVCISO (+14.4%), VL (+4.4%), and RF (+15.8%) muscle thicknesses and RF pennation angle (+22.1%) increased over the 9-month period in both groups similarly (p < 0.01), although no changes were observed in T100Hz, VAL, or VL EMG/M-wave. No changes were detected in any neuromuscular variables, except for coactivation. CONCLUSION Endurance training did not induce detectible, additional neuromuscular adaptations. However, the training-specific cycling power improvement in triathletes may reflect continued skill enhancement over the training period.
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Affiliation(s)
- Anthony Birat
- Fédération Française Triathlon, Saint Denis, France
- Université Clermont Auvergne, AME2P, Clermont-Ferrand, France
| | - Yoann M Garnier
- Université Clermont Auvergne, AME2P, Clermont-Ferrand, France
- University of Franche-Comté, SINERGIES, Besançon, France
| | - Alexis Dupuy
- Université Clermont Auvergne, AME2P, Clermont-Ferrand, France
- Centre de Ressources et d'Expertise de la Performance Sportive (CREPS), Bellerive-sur-Allier, France
| | | | | | | | | | - Mélanie Rance
- Centre de Ressources et d'Expertise de la Performance Sportive (CREPS), Bellerive-sur-Allier, France
| | - Claire Morel
- Centre de Ressources et d'Expertise de la Performance Sportive (CREPS), Bellerive-sur-Allier, France
| | - Anthony J Blazevich
- Centre for Human Performance, School of Medical and Health Sciences, Edith Cowan University, Joondalup, Western Australia, Australia
| | | | - Sébastien Ratel
- Université Clermont Auvergne, AME2P, Clermont-Ferrand, France
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Götschi T, Snedeker JG, Fitze DP, Sarto F, Spörri J, Franchi MV. Three-dimensional mapping of ultrasound-derived skeletal muscle shear wave velocity. Front Bioeng Biotechnol 2023; 11:1330301. [PMID: 38179131 PMCID: PMC10764491 DOI: 10.3389/fbioe.2023.1330301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Accepted: 12/08/2023] [Indexed: 01/06/2024] Open
Abstract
Introduction: The mechanical properties of skeletal muscle are indicative of its capacity to perform physical work, state of disease, or risk of injury. Ultrasound shear wave elastography conducts a quantitative analysis of a tissue's shear stiffness, but current implementations only provide two-dimensional measurements with limited spatial extent. We propose and assess a framework to overcome this inherent limitation by acquiring numerous and contiguous measurements while tracking the probe position to create a volumetric scan of the muscle. This volume reconstruction is then mapped into a parameterized representation in reference to geometric and anatomical properties of the muscle. Such an approach allows to quantify regional differences in muscle stiffness to be identified across the entire muscle volume assessed, which could be linked to functional implications. Methods: We performed shear wave elastography measurements on the vastus lateralis (VL) and the biceps femoris long head (BFlh) muscle of 16 healthy volunteers. We assessed test-retest reliability, explored the potential of the proposed framework in aggregating measurements of multiple subjects, and studied the acute effects of muscular contraction on the regional shear wave velocity post-measured at rest. Results: The proposed approach yielded moderate to good reliability (ICC between 0.578 and 0.801). Aggregation of multiple subject measurements revealed considerable but consistent regional variations in shear wave velocity. As a result of muscle contraction, the shear wave velocity was elevated in various regions of the muscle; showing pre-to-post regional differences for the radial assessement of VL and longitudinally for BFlh. Post-contraction shear wave velocity was associated with maximum eccentric hamstring strength produced during six Nordic hamstring exercise repetitions. Discussion and Conclusion: The presented approach provides reliable, spatially resolved representations of skeletal muscle shear wave velocity and is capable of detecting changes in three-dimensional shear wave velocity patterns, such as those induced by muscle contraction. The observed systematic inter-subject variations in shear wave velocity throughout skeletal muscle additionally underline the necessity of accurate spatial referencing of measurements. Short high-effort exercise bouts increase muscle shear wave velocity. Further studies should investigate the potential of shear wave elastography in predicting the muscle's capacity to perform work.
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Affiliation(s)
- Tobias Götschi
- Orthopaedic Biomechanics Laboratory, Department of Orthopaedics, Balgrist University Hospital, Zurich, Switzerland
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
- Department of Orthopaedics, Sports Medical Research Group, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
| | - Jess G. Snedeker
- Orthopaedic Biomechanics Laboratory, Department of Orthopaedics, Balgrist University Hospital, Zurich, Switzerland
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
| | - Daniel P. Fitze
- Department of Orthopaedics, Sports Medical Research Group, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
- Department of Orthopaedics, University Centre for Prevention and Sports Medicine, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
| | - Fabio Sarto
- Department of Biomedical Sciences, Institute of Physiology, University of Padua, Padua, Italy
| | - Jörg Spörri
- Department of Orthopaedics, Sports Medical Research Group, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
- Department of Orthopaedics, University Centre for Prevention and Sports Medicine, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
| | - Martino V. Franchi
- Department of Orthopaedics, Sports Medical Research Group, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
- Department of Biomedical Sciences, Institute of Physiology, University of Padua, Padua, Italy
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