No Effect Of Tattoos On Local Sweating Rate Or Sweat Electrolyte Concentrations During Exercise

PURPOSE: To compare LSR and local sweat sodium ([Na+]), chloride ([Cl-]), and potassium ([K+]) concentrations of PT skin and contralateral non-tattooed (NT) skin during self-paced cycling or fitness exercise. METHODS: Seventeen moderately-trained men (n = 8) and women (n = 9) (36 ± 10 years) with at least one permanent tattoo (>1 year old) on the arm thorax, or scapular region were tested during self-paced indoor cycling (n = 3), outdoor cycling (n = 4), or outdoor group fitness sessions (n = 10). Air temperature and relative humidity were 28.4 ± 3.3 °C and 57.8 ± 9.7%, respectively. Before exercise, skin was cleaned with alcohol and patches (3 M Tegaderm+Pad) were placed on the tattoo and the contralateral site. Patches were monitored during exercise and removed upon moderate saturation. LSR was calculated from sweat mass over patch surface area (11.9 cm2) and duration (65 ± 14 min). Sweat was analyzed for [Na+], [Cl-], and [K+] by ion chromatography. To evaluate differences between PT and NT skin, paired t-tests or Wilcoxon signed rank tests were used. Significance level was set at p < 0.05. Bland Altman analysis and 95% limits of agreement (LOA) were used to assess agreement and intraclass correlation coefficient (ICC) and coefficients of variation (CV) were performed to analyze reliability between PT and NT skin. RESULTS: There were no differences between PT and NT skin for LSR (1.1 ± 0.5 vs. 1.0 ± 0.4 mg/cm2/min; p = 0.32), sweat [Na+] (55.2 ± 23.2 vs. 53.2 ± 23.3 mM; p = 0.27), sweat [Cl-] (45.9 ± 23.0 vs. 44.5 ± 22.6 mM; p = 0.42), or sweat [K+] (5.5 ± 1.4 vs. 5.6 ± 1.4 mM; p = 0.81). Bland Altman 95% LOA were -0.5 to 0.7 for LSR, -12.0 to 16.0 for sweat [Na+], -12.6 to 15.4 for sweat [Cl-], and -2.0 to 1.8 for sweat [K+]. ICCs and CVs showed excellent reliability for sweat [Na+] (0.95, 9.1%) and sweat [Cl-] (0.95, 11.5%) and good reliability for LSR (0.78, 16.5%) and sweat [K+] (0.75, 7.7%). CONCLUSION: PT skin and NT skin showed no significant difference in LSR, sweat [Na+], [Cl-], or [K+], with CVs similar to those previously reported for NT bilateral skin regions. These findings suggest there is no effect of tattoos on local sweating rate and electrolyte concentrations during exercise.