Papadakis Zacharias, Panoutsakopoulos Vassilios, Schwarz Antonella, Antonio Jose
Barry University, Human Performance Laboratory, Department of Health Promotion and Clinical Practice, Miami Shores, FL, USA.
Aristotle University of Thessaloniki, Biomechanics Laboratory, School of Physical Education and Sport Science at Thessaloniki, Thessaloniki, Greece.
J Int Soc Sports Nutr. 2025 Dec;22(1):2501063. doi: 10.1080/15502783.2025.2501063. Epub 2025 May 4.
Caffeine's ergogenic potential in vertical jumping remains contested, particularly at dosages compliant with collegiate athletic regulations. The NCAA enforces a caffeine urinary threshold equivalent to ~5 mg/kg body mass, yet evidence supporting its efficacy in enhancing explosive performance among trained athletes is inconsistent. This study examined whether acute caffeine ingestion at this threshold improves squat jump (SJ) and countermovement jump (CMJ) performance in NCAA Division II student-athletes, while exploring sex-specific responses and trial-to-trial variability.
Forty NCAA Division II athletes (18 females, 22 males; 21.3 ± 2.4 years) participated in a single-blind, randomized, crossover trial. Participants ingested 5 mg/kg caffeine or placebo, followed by SJ and CMJ testing on a force platform 60 minutes post-consumption. Three trials per jump type were retained to preserve intra-individual variance. Linear mixed-effects models (LMMs) assessed fixed effects of condition, sex, and trials, with random intercepts and slopes accounting for individual variability. A priori power analyses guided sample size determination, targeting sensitivity to detect small-to-medium effects (Cohen's f ≥ 0.2).
Caffeine elicited trivial, non-significant differences in SJ (β = -0.24 cm, = 0.646) and CMJ (β = -0.71 cm, = 0.183) heights compared to placebo. Males outperformed females in both SJ (Δ = 9.50 cm, < 0.001) and CMJ (Δ = 11.30 cm, < 0.001), though no condition-by-sex interactions emerged. Trial effects were observed, with SJ improving 2.31 cm ( < 0.001) and CMJ 1.05 cm ( = 0.014) from first to second attempts, suggesting warm-up or neuromuscular potentiation. High intraclass correlation coefficients (ICC = 0.76-0.85) underscored substantial interindividual variability. Models demonstrated robust fit (conditional R = 0.86-0.92), with sufficient power to detect medium-to-large effects (f ≥ 0.25).
A 5 mg/kg caffeine dose, compliant with NCAA thresholds, did not enhance vertical jump performance in habituated collegiate athletes, challenging prior assertions of its universal ergogenicity for ballistic tasks. While sex differences in baseline performance persisted, caffeine did not modulate these disparities, implicating neuromuscular and anthropometric factors as primary determinants. The absence of ergogenic effects aligns with NCAA safety-focused policies but highlights the need for personalized dosing strategies and research into higher doses, genetic variability, and hormonal influences. Future studies should integrate biomechanical metrics and controlled hormonal assessments to elucidate caffeine's nuanced role in anaerobic power sports.
咖啡因在垂直跳跃中的促力能潜力仍存在争议，尤其是在符合大学体育规定的剂量下。美国全国大学体育协会（NCAA）规定的咖啡因尿液阈值相当于约5毫克/千克体重，但支持其在增强训练有素的运动员爆发力方面功效的证据并不一致。本研究调查了在此阈值下急性摄入咖啡因是否能改善NCAA二级学生运动员的深蹲跳（SJ）和反向移动跳（CMJ）成绩，同时探讨性别特异性反应和每次试验间的变异性。
40名NCAA二级运动员（18名女性，22名男性；年龄21.3±2.4岁）参与了一项单盲、随机、交叉试验。参与者摄入5毫克/千克咖啡因或安慰剂，然后在摄入后60分钟在测力平台上进行SJ和CMJ测试。每种跳跃类型保留三次试验以保留个体内差异。线性混合效应模型（LMMs）评估了条件、性别和试验的固定效应，随机截距和斜率考虑了个体变异性。先验功效分析指导样本量的确定，目标是检测中小效应的敏感性（科恩f≥0.2）。
与安慰剂相比，咖啡因在SJ（β=-0.24厘米，P=0.646）和CMJ（β=-0.71厘米，P=0.183）高度上引起的差异微不足道且无统计学意义。男性在SJ（差值=9.50厘米，P<0.001）和CMJ（差值=11.30厘米，P<0.001）方面均优于女性，尽管未出现条件与性别之间的交互作用。观察到试验效应，从第一次尝试到第二次尝试，SJ提高了2.31厘米（P<0.001），CMJ提高了1.05厘米（P=0.014），表明存在热身或神经肌肉增强作用。高组内相关系数（ICC=0.76-0.85）强调了个体间的巨大变异性。模型显示拟合良好（条件R=0.86-0.92），有足够的功效检测中到大效应（f≥0.25）。
符合NCAA阈值的5毫克/千克咖啡因剂量并未提高习惯化的大学运动员的垂直跳跃成绩，这对先前关于其对弹道任务具有普遍促力能性的断言提出了挑战。虽然基线表现存在性别差异，但咖啡因并未调节这些差异，这表明神经肌肉和人体测量因素是主要决定因素。缺乏促力能效应与NCAA以安全为重点的政策一致，但突出了个性化给药策略以及对更高剂量、基因变异性和激素影响进行研究的必要性。未来的研究应整合生物力学指标和受控的激素评估，以阐明咖啡因在无氧力量运动中的细微作用。
