The randomized, crossover, double-blind study assessed the effect of caffeine (CAF) supplementation in various quantities (3 mg/kg−1 (CAF-3), 6 mg/kg−1 (CAF-6), and 9 mg/kg−1 (CAF-9)) on performance outcomes and side effects in 16 well-trained handball and football athletes.
Most research on caffeine supplementation is conducted with individual adult male athletes, making this study and its results imperative as horizons broaden in the world of sports, the authors noted in the journal Nutrients.
Results showed that for short-term high-intensity exercise, there was little performance increase with CAF-3, while CAF-6 and CAF-9 increased all performance outcomes, however the higher dosage was associated with a notable increase in the frequency of adverse side effects, they concluded.
Insubstantial guidelines
Caffeine (CAF), a pharmacologically active substance, gained popularity among athletes after its removal from the World Anti-Doping Agency's prohibited substances list in 2004 and is now recognized as one of the most common ergogenic aids in sports.
The psychoactive substance is proposed to enhance performance through various potential mechanisms, which include preserving muscle glycogen by inhibiting phosphodiesterase, promoting calcium release from the sarcoplasmic reticulum and counteracting the effects of adenosine A1 and A2 receptors in the central nervous system.
However, the effectiveness of CAF depends on factors like dosage, form, training status, timing of consumption, habitual intake, sex and exercise type.
Current CAF supplementation guidelines, primarily based on studies involving male athletes, are identical to guidelines for females, despite there being a lack of research specifically analyzing the effect on female athletes.
And while CAF supplementation may improve performance in individual sports, its effectiveness is less evident in team sports, where success is determined by a combination of physical condition, technical skill and tactical understanding.
Meanwhile, the trend of early sports specialization is increasing among young athletes, driven by pressure from coaches, parents and peers.
"This trend may lead young athletes to use supplements, including caffeine, without age-specific recommendations, potentially causing adverse effects as while performance advantages are observed in adults, it's unclear if the same benefits apply to younger individuals,” the authors wrote.
The study therefore aimed to fill gaps in existing data, particularly regarding the impact of different CAF dosages on high-intensity physical performance and potential side effects among young female team-sports athletes.
Caffeine supplementation
All participants (n = 16; age: 16.9 ± 0.6 y; height: 1.64 ± 0.1 m; BMI: 21.6 ± 1.5 kg·m−2) were already mild CAF consumers.
Each athlete performed four experimental sessions after ingesting either a placebo or capsules containing doses of CAF (Bulk Powders): either CAF-3, CAF-6 or CAF-9, with an in-between washout period of at least 72 hours.
In each experimental session, 60 minutes after ingesting the capsules, participants underwent a countermovement jumps test (CMJ), modified agility t-test (MATT), repeated sprint ability (RSA) test and a rating of perceived exertion (RPE), and completed the CAF side effects questionnaire.
Results showed that in comparison to placebo, the MATT, RSA mean and RSA best performances were significantly greater only under the CAF-6 and CAF-9 conditions. Although the RPE scores remained unchanged, CMJ performance improved under all CAF conditions.
Notably, no significant difference between the CAF-6 and CAF-9 conditions was observed for any parameters, but higher incidences of side effects were noted for the CAF-9 condition: 24 hours after CAF-9 ingestion, more athletes reported increased urine output (31.25%), gastrointestinal problems (31.25%), headache (25%) and insomnia (25%).
“Findings highlight the recommendation for a moderate CAF dosage of 6 mg/kg−1 rather than 3 or 9 mg/kg−1 to enhance various aspects of short-term maximal performance in mild-CAF-consumer female team-sports athletes while mitigating the occurrence of adverse CAF side effects,” the authors concluded.
“Athletes and coaches may find this recommendation useful in implementing caffeine intake strategies throughout busy training and tournament schedules.”
Journal: Nutrients
doi: 10.3390/nu16050640
“Optimizing Short-Term Maximal Exercise Performance: The Superior Efficacy of a 6 mg/kg Caffeine Dose over 3 or 9 mg/kg in Young Female Team-Sports Athletes.”
Authors: Houda Bougrine et al.