The influence of caffeine ingestion on strength and power performance in female team-sport players

Abstract

BackgroundThe aim of this study was to examine the influence of caffeine supplementation on knee flexor and knee extensor strength before, during and after intermittent running exercise in female team-sport players taking oral contraceptive steroids (OCS).MethodTen healthy females (24 ± 4 years; 59.7 ± 3.5 kg; undertaking 2–6 training sessions per week) taking low-dose monophasic oral contraceptives of the same hormonal composition took part in a randomised, double-blind, placebo-controlled crossover-design trial. Sixty minutes following the ingestion of a capsule containing 6 mg∙kg−1 body mass anhydrous caffeine or artificial sweetener (placebo), participants completed a 90-min intermittent treadmill-running protocol. Isometric strength performance and eccentric and concentric strength and power of the knee flexors and knee extensors (using isokinetic dynamometer), as well as countermovement jump (CMJ), was measured before, during and after the exercise protocol, as well as ~12 h post-exercise. Blood samples were taken before, during and post-exercise to measure glucose, insulin and free fatty acids (FFA).ResultsCaffeine supplementation significantly increased eccentric strength of the knee flexors (P < 0.05) and eccentric power of both the knee flexors (P < 0.05) and extensors (P < 0.05). However, there was no effect on isometric or concentric parameters, or CMJ performance. FFA was elevated with caffeine supplementation over time (P < 0.05) while levels of glucose and insulin were not affected by caffeine intake.ConclusionCaffeine supplementation increased eccentric strength and power in female team-sport players taking OCS both during an intermittent running protocol and the following morning.

Caffeine increases strength and power performance in resistance‐trained females during early follicular phase

“…The effect of caffeine on maximal isometric strength observed in this study is in agreement with Warren et al's meta-analysis findings, 6 who found caffeine to have a moderate effect on isometric knee extensor strength. On the other hand, Ali et al 14 found no effects of 6 mg•kg −1 caffeine on knee extensor isometric strength in women. However, their protocol measured maximal muscle strength between fatiguing blocks of sprints and consequently, might have masked a caffeine-induced effect on maximal strength.…”

“…Furthermore, variations in strength and power have been demonstrated throughout the menstrual cycle, 13 which can cause noise in performance data and affect overall results. Taken together, although there are a number of studies demonstrating that caffeine clearly has an ergogenic effect in females, 9,[14][15][16] the information about the effect of caffeine on muscle performance in women is uncertain, especially in strength and power performance. As an example, a recent meta-subgroup analysis examined the effects of caffeine on muscle power in females for the first time.…”

Caffeine improves various aspects of athletic performance in adolescents independent of their 163 C > A CYP1A2 genotypes

“…In the present study, CAF failed to increase CMJ and SJ performance, corroborating previous studies showing no improvement in CMJ after CAF intake in male adult soccer players 32 and in female team-sport players. 33 Other studies, however, have reported an ergogenic effect of CAF on jump performance in male adolescent basketball players 34 (ES = 0.181) and male adult volleyball players 12 (ES = 0.399). It is difficult to explain the reason for these contradictory findings, but an improvement in jump performance with CAF ingestion, when present, would be associated with a better neuromuscular function, mainly due to the higher conduction speed and/or the greater recruitment of muscle fibers.…”

Acute Caffeine Supplementation Does Not Improve Performance in Trained CrossFit® Athletes

“…Additionally, the effects of caffeine supplementation were evaluated in men and may not be generalizable to women CrossFit ® participants. Caffeine supplementation in women is complicated by the effects of estrogen and oral contraceptive steroids on caffeine metabolism, both of which appear to prolong the effects of caffeine in the body [5,51]. To increase internal validity, participants performed the workout alone, with no clock visible, and no music was playing.…”