No Effect of Permanent Tattoos on Local Sweat Concentration or Excretion Rate of Urea Nitrogen, Cortisol, Glucose, or Lactate During Exercise

Abstract

Permanent tattooing is common on areas of the skin typically sampled for sweat diagnostics, yet its potential to alter local sweat concentration and excretion rate (ER) of metabolites and other compounds is unknown. The purpose of this study was to investigate the influence of tattooed skin (TAT) on local sweat concentration and ER of urea nitrogen (UN), cortisol (CORT), glucose (GLU) and lactate (LAC) when compared to contralateral non‐tattooed skin (NT) during a group fitness exercise session. Moderately trained participants (males n=8, females n=8, 34±8 y) with at least one permanent tattoo (age of tattoo 7±5 y) on the upper body (arm, scapula, or thorax regions) underwent a ~60 minute outdoor (~27±3°C, 63±4% RH, 26±3°C WBGT) group fitness exercise session. Sweat was collected with absorbent patches (3MTMTegaderm+PAD) placed on the TAT and on NT. Patches were monitored during exercise and removed upon moderate saturation. Local sweat rate (LSR) was calculated from sweat mass over patch surface area (11.9 cm2) and exercise duration (56±2 min). Excretion rates (ER) were calculated as the product of analyte concentration and local SR. Sweat was analyzed by ELISA for UN (Invitrogen, ThermoFisher Scientific), CORT (Invitrogen, ThermoFisher Scientific), GLU (Caymen Chemical Co.) and LAC (LSBio). To evaluate differences between TAT and NT skin, paired t‐tests or Wilcoxon signed rank tests were used. Significance level was set at p<0.05. Data are presented as mean±SD or median±IQR for normally and non‐normally distributed data respectively. There were no differences in LSR for TAT vs. NT conditions (1.1±0.7 vs 1.2±0.6 mg/cm2/min; p=0.93). TAT and NT skin had similar concentrations for UN (19.2±6.0 vs 20.7±6.1 mg/dL; p=0.28), CORT (2.4±1.3 vs 2.5±1.4 ng/mL; p=0.41), GLU (0.22±0.3 vs 0.24±0.2 mg/dL; p=0.31), and LAC (5.8±6.3 vs 5.9±6.6 mM; p=0.83). ERs were also similar for all analytes: UN (252±150 vs 270±136 ng/cm2/min; p=0.34), CORT (1.8±3.4 vs 2.1±3.4 pg/cm2/min; p=0.46), GLU (2.3±1.6 vs 2.3±2.4 ng/cm2/min; p=0.40) and LAC (6.4±10.9 vs 7.1±10.1 ng/cm2/min; p>0.999). In conclusion, TAT does not appear to affect the LSR, concentration, or ER of select analytes during ~60 min of fitness exercise.