An Inconvenient Truth: Transdermal Buffering Lotions Fail to Improve High-Intensity Cycling Intervals or Time Trial Performance

Background: /Objectives: Transdermal bicarbonate (TBC) or carnosine (TC) have been sold as a convenient way to improve performance, though little evidence indicates they are ef-fective. The purpose of this study was to investigate if TBC or TC, applied as advertised, improve high-intensity endurance cycling. Methods: Using the Zwift online platform, fif-teen cyclists completed four ~50-km cycling trials that included three long sprints and three short climbs, plus a final lap time trial (TT). Trials included a familiarization (FAM) trial followed by three randomized trials using a TBC, TC, or placebo (PLAC) lotion. Trial data were analyzed using general linear models to compare differences between condi-tions across ~50-km cycling trials. Results: Mean ± SD 60-min mean max power (MMP) was 2.9 ± 0.9 W/kg and ranged from 1.3 to 4.1 W/kg. Trials were five 9.1 km laps lasting 89.8 ± 17.0 min long. Relative to MMP60, interval laps (2 – 4) were ridden at 86.4 ± 7.3% and climbs at 131.6 ± 21.1%, while sprints averaged 83.2 ± 17.7% of MMP30s. The lap 5 TT was ridden at 95.4 ± 8.7% of MMP20 and 87.5% ± 7.4% of MHR. While there were no statistical differences in performance between any treatment trial, FAM trials were significantly lower (p < 0.05) in power output measures, but not HR and RPE. Conclusions: Based on the available evidence from this and prior research, there appears to be no apparent ergogenic benefit from either TBC or TC during high intensity cycling performance.