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Randomized Controlled Trial
. 2025 Dec;22(1):2528533.
doi: 10.1080/15502783.2025.2528533. Epub 2025 Jul 8.

Exercise with fasting or isotonic drink? A randomized controlled trial in youth elite basketball players

Petra Márton  1   2 , Luca Kata Bátai  1   2 , Titanilla Takács  3 , Emese Csulak  1   2 , Anna Réka Kiss  1   2 , Bence Kopper  4 , Liliána Erzsébet Szabó  1   2 , Dorottya Balla  1   2 , Iván Petrov  1   2 , Lilla Lázár  1   2 , Hajnalka Vágó  1   2 , Béla Merkely  1   2 , Nóra Sydó  1   2
Affiliations
Randomized Controlled Trial

Exercise with fasting or isotonic drink? A randomized controlled trial in youth elite basketball players

Petra Márton et al. J Int Soc Sports Nutr. 2025 Dec.

Abstract

Background: Pre-exercise carbohydrate intake is known to influence performance; however, data describing their effect on cardiorespiratory parameters is scarce. This study aimed to assess the effects of isotonic drink consumption on cardiopulmonary exercise test (CPET) parameters in elitemale youth basketball players.

Methods: The athletes were randomized into a fasting (400 ml mineral water) and an isotonic drink (400 ml 7% isotonic solution) group respectively, and consumed the drinks 30 minutes before the CPET. Pre-, peak- and post-CPET glucose levels were measured. Borg and lactate were assessed every 2 minutes during the test.

Results: Seventy-one athletes (age: 15.9 ± 1.8 years) were included in the study. The isotonic drink group had higher pre- and post-CPET glucose levels (p < 0.05). They reported a lower Borg scale at the 2nd, 6th, and 10th minutes (p < 0.05), while their lactate levels were lower at the 14th minute (p < 0.05). Regression analysis showed that fasting was associated with higher Borg scale ratings (β-coefficient: 0.72, p < 0.001) and increased lactate accumulation over time (β-coefficient: 0.13, p = 0.01). No difference was found in exercise duration or maximal aerobic capacity.

Conclusions: Single-dose isotonic drink consumption before CPET reduces perceived exertion and moderates lactate accumulation, which may suggest a beneficial effect during the exercise test.

Keywords: Sports performance; basketball; carbohydrate; isotonic drink; nutrition.

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Conflict of interest statement

No potential conflict of interest was reported by the author(s).

Figures

Figure 1.
Figure 1.
Study design and interventions.
Figure 2.
Figure 2.
Longitudinal tracking of the Borg scale during CPET exam in the fasting and in the isotonic drink groups.
Figure 3.
Figure 3.
Longitudinal tracking of lactate levels during the CPET exam in the fasting and in the isotonic drink groups.
Figure 4.
Figure 4.
Correlation between Borg scale ratings and lactate levels.
See this image and copyright information in PMC

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