Caffeine Increases Exercise Performance, Maximal Oxygen Uptake, and Oxygen Deficit in Elite Male Endurance Athletes.
Medicine and Science in Sports and Exercise 2021
PubMed ID : 34033621
Caffeine increases endurance performance but the physiological mechanisms improving high intensity endurance capacity are not well characterised.
The aim of the present study was to test the hypothesis that caffeine increases maximal oxygen uptake (VO2max), and to characterise the physiological mechanisms underpinning improved high intensity endurance capacity.
23 elite endurance trained male athletes were tested twice with and twice without caffeine (four tests) in a randomized, double-blinded and placebo-controlled study with cross-over-design. Caffeine (4.5 mg·kg-1) or placebo was consumed 45 min before standardized warm-up. Time-to-exhaustion during an incremental test (running 10.5° incline, start speed 10.0 km·h-1, and 0.5 km·h-1 increase in speed every 30 s) determined performance. Oxygen uptake was measured continuously to determine VO2max and O2-deficit was calculated.
Caffeine increased time-to-exhaustion from 355 ± 41 to 375 ± 41 s (Δ19.4 ± 16.5 s; p < 0.001). Importantly, caffeine increased VO2max from 75.8 ± 5.6 to 76.7 ± 6.0 ml·kg-1·min-1 (Δ 0.9 ± 1.7 ml·kg-1·min-1; p < 0.003). Caffeine increased maximal heart rate (HRpeak) and ventilation (VEpeak). Caffeine increased O2-deficit from 63.1 ± 18.2 to 69.5 ± 17.5 ml·kg-1 (p < 0.02) and blood lactate compared to placebo. The increase in time-to-exhaustion after caffeine ingestion was reduced to 11.7 s after adjustment for the increase in VO2max. Caffeine did not significantly increase VO2max after adjustment for VEpeak and HRpeak. Adjustment for O2-deficit and lactate explained 6.2 s of the caffeine-induced increase in time-to-exhaustion. The increase in VO2max, ventilation, heart rate, O2-deficit and lactate explained 63% of the increased performance after caffeine intake.
Caffeine increased VO2max in elite athletes, which contributed to improvement in high intensity endurance performance. Increases in O2-deficit and lactate, also contributed to the caffeine-induced improvement in endurance performance.