AUTHOR=Cosio Pedro L. , Moreno-Simonet Lia , Porcelli Aniello , Lloret Mario , Padulles Xavier , Padulles Josep M. , Farran-Codina Andreu , Cadefau Joan A. 

TITLE=Assessment of inter-individual variability in hamstring muscle recovery after a sport-specific sprint training in women and men

JOURNAL=Frontiers in Physiology

VOLUME=14

YEAR=2024

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2023.1331878

DOI=10.3389/fphys.2023.1331878

ISSN=1664-042X

ABSTRACT=<p><bold>Background:</bold> Hamstring muscles are most affected by multiple sprint-based sports as a result of muscle strain during sprinting, leading to reduced performance and increased risk of injury. Therefore, the purpose of the study was to assess inter-individual variability in hamstrings recovery after a sport-specific repeated-sprint training (RST), through sprint-specific markers of muscle recovery and associated muscle damage biomarkers in women and men.</p><p><bold>Methods:</bold> Healthy females (<italic>n</italic> = 14) and males (<italic>n</italic> = 15) underwent 10 repeated 40-m sprints with a 3-min rest pause between each repetition. Force-generating capacity (FGC) by the <italic>90°</italic><sub><italic>hip</italic></sub><italic>:20°</italic><sub><italic>knee</italic></sub><italic>test</italic> and range of motion <italic>Jurdan test</italic>, together with serum biomarkers [sarcomeric mitochondrial creatine kinase (sMtCK), oxidative stress, irisin] were tested at baseline and 24-, 48- and 72-h post-exercise through a repeated measures design. Participants were classified according to FGC loss into high responders (HR) and low responders (LR).</p><p><bold>Results:</bold> 21 individuals (10 females, 11 males) were classified as HR (FGC loss &gt;20% and recovery &gt;48 h), while 8 individuals (4 females, 4 males) were classified as LR. HR individuals showed unrecovered maximal voluntary isometric contraction (MVIC) torque until 72 h post-training (<italic>p</italic> = 0.003, n<sub>p</sub><sup>2</sup> = 0.170), whereas only HR males showed decreased range of motion (<italic>p</italic> = 0.026, n<sub>p</sub><sup>2</sup> = 0.116). HR individuals also showed increased sMtCK (<italic>p</italic> = 0.016, n<sub>p</sub><sup>2</sup> = 0.128), oxidative stress (<italic>p</italic> = 0.038, n<sub>p</sub><sup>2</sup> = 0.106) and irisin (<italic>p</italic> = 0.019, n<sub>p</sub><sup>2</sup> = 0.123).</p><p><bold>Conclusion:</bold> There is inter-individual variability in the muscular response to a sport-specific RST, identifiable by MVIC torque assessment. The findings support that the <italic>90°</italic><sub><italic>hip</italic></sub><italic>:20°</italic><sub><italic>knee</italic></sub><italic>test</italic> is a powerful indirect test to screen hamstrings recovery in both women and men, in a cost-effective way. However, the <italic>Jurdan test</italic> might not be able to monitor hamstrings recovery in sportswomen after RST. Decreases in muscle capacity are linked to damage to muscle sarcolemma and mitochondria until 72 h post-exercise. Overall, 72 h will not be adequate time to restore hamstrings structure and function after a sport-specific RST in both female and male responders.</p>