Caffeine, a popular ergogenic supplement, induces neural and vascular changes that may influence coagulation and/or fibrinolysis at rest and during exercise.
The purpose of this study was to assess the effect of a single dose of caffeine on measures of coagulation and fibrinolysis before and after a single bout of high-intensity exercise.
Forty-eight men (age, 23 ± 3 yr; body mass index, 24 ± 3 kg·m−2) completed two trials, with 6 mg·kg−1 of caffeine (CAFF) or placebo (PLAC), in random order, followed by a maximal cycle ergometer test. Plasma concentrations of fibrinogen, factor VIII antigen, active tissue plasminogen activator (tPA:c), tissue plasminogen activator antigen (tPA:g), and active plasminogen activator inhibitor-1 (PAI-1:c) were assessed at baseline and immediately after exercise.
Exercise led to significant changes in tPA:c (Δ 8.5 ± 4.36 IU·mL−1 for CAFF, 6.6 ± 3.7 for PLAC), tPA:g (Δ 2.4 ± 3.2 ng·mL−1 for CAFF, 1.9 ± 3.1 for PLAC), fibrinogen (Δ 30.6 ± 61.4 mg·dL−1 for CAFF, 28.1 ± 66.4 for PLAC), and PAI-1:c (Δ −3.4 ± 7.9 IU·mL−1 for CAFF, −4.0 ± 12.0 for PLAC) (all P < 0.05), but no effect of condition or time–condition interactions were observed. Main effects of time, condition, and a significant time–condition interaction were observed for factor VIII, which increased from 1.0 ± 0.4 IU·mL−1 to 3.3 ± 1.3 IU·mL−1 with CAFF and 1.0 ± 0.4 IU·mL−1 to 2.4 ± 0.9 IU·mL−1 with PLAC.
Coagulation potential during exercise is augmented after caffeine intake, without a similar increase in fibrinolysis. These results suggest caffeine intake may increase risk of a thrombotic event during exercise.
1Integrative Exercise Physiology Laboratory, Ball State University, Muncie, IN; and
2James Madison University, Harrisonburg, VA
Address for correspondence: Paul R. Nagelkirk, Ph.D., HP 360 Ball State University, Muncie IN, 47306; E-mail: email@example.com.
Submitted for publication December 2017.
Accepted for publication October 2018.