An Inconvenient Truth: Transdermal Buffering Lotions Appear to Offer No Significant Performance Improvement

Background/Objectives: Transdermal bicarbonate (TBC) or carnosine (TC) have been sold as a convenient ergogenic aid, though little evidence supports these claims. The purpose of this study was to investigate if TBC or TC would improve high-intensity endurance cycling. Methods: Data were collected remotely using Zwift online platform. Fifteen cyclists completed four trials comprising five 9.1 km laps: warm-up lap, three interval laps (3 × 900 m hills, and 3 × 300 m sprints), and a 9.1 km time trial (TT) lap. A familiarization (FAM) trial followed by three randomized trials using a TBC, TC, or placebo (PLAC) lotion were completed. Trial data were assessed using general linear models to compare differences between conditions across cycling trials (p < 0.05). Results: Mean ± SD. 60 min mean max power (MMP60) was 2.9 ± 0.9 W/kg and ranged from 1.3 to 4.1 W/kg for participants. Exercise trials were 89.8 ± 17.0 min long. Laps 2–4 were ridden at 86.4 ± 7.3% and hill climbs at 131.6 ± 21.1% of MMP60, while sprints averaged 83.2 ± 17.7% of 30 s mean max power (MMP30s) and the TT ridden at 95.4 ± 8.7% of 20 min mean max power (MMP20). FAM trials were significantly lower (p < 0.05) in all power output measures, except TC sprints, and no heart rate or rating of perceived exertion differences. Similarly, there were no statistical differences in performance between any condition trials or placebo trial, but TBC hill climb power was significantly higher (p = 0.038) than TC trials. Conclusions: There are no apparent ergogenic benefits from TBC or TC during high intensity cycling performance.