Purpose

AUTHOR=Korkmaz Eryılmaz Selcen , Karakaş Selçuk , Boyraz Cumhur , Günaştı Özgür , Kılcı Abdullah , Özdemir Çiğdem , Özgünen Kerem , Koç Muhammed , Adaş Ümit , Kurdak Sadi TITLE=Respiratory responses and isocapnic buffering phase in child and youth soccer players during an incremental exercise test JOURNAL=Frontiers in Physiology VOLUME=15 YEAR=2024 URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2024.1407759 DOI=10.3389/fphys.2024.1407759 ISSN=1664-042X ABSTRACT=Purpose

This study investigated the respiratory response and isocapnic buffering (IB) phase during an incremental exercise test to exhaustion in 16 child soccer players (11.9±0.9 years) and 18 youth soccer players (18.2±2.9 years).

Methods

The IB phase was calculated as the difference in oxygen uptake (VO2) between the respiratory compensation point (RCP) and metabolic threshold (MT) and expressed in either absolute or relative values.

Results

The maximal oxygen uptake (VO_2max) was higher in youth players than in child players. For youth players, VO_2max was measured at 55.9 ± 3.6 mL min⁻¹ kg⁻¹ and 74.9 ± 4.8 mL min⁻¹ kg^−0.75, while for child players, VO_2max was 50.8 ± 4.1 mL min⁻¹ kg⁻¹ and 67.2 ± 6.1 mL min⁻¹ kg^−0.75 (p < 0.001). MT and RCP occurred at 69.8 ± 6.7% and 90.9 ± 6.9% of VO_2max in child players and at 73.9 ± 5.1% and 91.5 ± 4.5% of VO_2max in youth players, respectively. The two groups had no significant difference (p > 0.05). Absolute IB (10.6 ± 2.8 vs 9.7 ± 3.1 mL min⁻¹ kg⁻¹), relative IB (23.1 ± 5.7 vs 19.1 ± 6.1), and the ratio of RCP VO₂ to MT VO₂ (1.3 ± 0.09 vs 1.24 ± 0.09) were similar in child and youth players (p > 0.05). There was no difference in minute ventilation (V̇E, mL min⁻¹ kg⁻¹) and respiratory exchange ratio during exercise between the two groups (p > 0.05). During exercise, respiratory frequency, ventilatory equivalent for carbon dioxide (VE/VCO₂) and oxygen (VE/VO₂), VE/VCO₂ slope, end-tidal O₂ pressure were higher in child players than in youth players, while tidal volume (L kg⁻¹), O₂ pulse, and end-tidal CO₂ pressure were lower (p < 0.05).

Conclusion

Despite differences in aerobic capacity and ventilatory response to exercise, child players showed similar IB phase as youth players. Although child players have lower ventilation efficiency than youth players, the higher ventilation response for a given VCO₂ may provide an advantage in regulating acid-base balance during intense exercise.