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. 2025 Mar 5:16:1480776.
doi: 10.3389/fphys.2025.1480776. eCollection 2025.

Influence of repeated sprint exercise on leukocyte morphology in adolescent athletes at different biological maturation rates

Fernanda Oliveira  1 , Paulo Almeida-Neto  1 , Geraldo Barroso Cavalcanti Júnior  2   3 , Marcela Abbott Galvão Ururahy  2   3 , Maria Angela Dantas  1 , Breno Guilherme De Araujo Tinoco Cabral  2   3 , Paulo Moreira Silva Dantas  2   3
Affiliations

Influence of repeated sprint exercise on leukocyte morphology in adolescent athletes at different biological maturation rates

Fernanda Oliveira et al. Front Physiol. .

Abstract

Background: After performing strenuous physical exercises such as repeated sprint exercise (RSE), the leukocyte morphology undergoes changes suggesting immunodepression. Furthermore, it has been previously suggested that, in pediatrics, leukocyte changes may be influenced by the rates of the biological maturation (BM) process, which varies among individuals of similar chronological age.

Objective: To investigate the influence of RSE on leukocyte morphology in adolescent athletes at different rates of BM.

Methods: We conducted an experimental trial with a final sample consisting 21 adolescent athletes (male sex, age = 12.7 ± 1.2) underwent an RSE protocol, and blood samples were collected at "before, after, and 2 h post" moments. Based on the BM rates assessed by a predictive equation of skeletal age, participants were divided into two groups (Accelerated [n = 10] and Synchronized [n = 11]). Leukocyte morphology was analyzed microscopically and by leukogram.

Results: Regardless of the BM rates, a time effect was observed on the absolute levels of total leukocytes (g/L: η2p = 0.36), lymphocytes (g/L: η2p = 0.50, %: η2p = 0.29), segmented neutrophils (g/L: η2p = 0.16, %: η2p = 0.43), and neutrophil-to-lymphocyte ratio [NLR] (g/L: η2p = 0.30). The synchronized BM group showed higher values than the accelerated group for total leukocyte levels (moments after and 2 h post [η2p = 0.10; p < 0.001]) and segmented neutrophils (moments after and 2 h post [η2p = 0.10; p < 0.001]).

Conclusion: In adolescent athletes, changes caused by RSE in leukocyte morphology appear to be dependent on the BM rates.

Keywords: biological maturation; children; immunology; lymphocyte; sport.

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Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

FIGURE 1
FIGURE 1
Procedures. RSE: Repeated sprint exercise. This figure was created in app. napkin.ai [free version].
FIGURE 2
FIGURE 2
General linear model to make comparisons considering the different rates of skeletal maturation (synchronized and accelerated) and the effect of time (before, after and 2 h post). GLM: General Linear Model. NLR: Total neutrophils/lymphocytes ratio. g/L: Cell per liter. %: Percentage. ‡: Higher than the Accelerated group [Post hoc Bonferroni (p < 0.05)]. (A) Higher than the Before moment [Post hoc Bonferroni (p < 0.05)]. (B) Superior to the Before and After moments [Post hoc Bonferroni (p < 0.05)]. (C) Higher than Before and 2 h post moments [Post hoc Bonferroni (p < 0.05)]. (A): analysis related to lymphocytes. (B): analysis related to NLR. (C,D): analysis related to lymphocytes. (E,F): analysis related to segmented neutrophils.
See this image and copyright information in PMC

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