Multiple regression analysis to determine the effect of sweating rate and tattoo characteristics on sweat outcome measures during exercise

Abstract

Purpose

To compare local sweating rate (LSR) and local sweat sodium ([Na⁺]), chloride ([Cl⁻]), and potassium ([K⁺]) concentrations of tattooed skin and contralateral non-tattooed skin during exercise.

Methods

Thirty-three recreational exercisers (17 men, 16 women) with ≥ 1 unilateral permanent tattoo on the torso/arms were tested during cycling, running, or fitness sessions (26 ± 4 °C and 54 ± 13% relative humidity). Forty-eight tattoos with a range of ink colors, ages (3 weeks to 20 years), and densities (10–100%) were included. Before exercise, the skin was cleaned with alcohol and patches (3 M Tegaderm + Pad) were placed on the tattooed and contralateral non-tattooed skin. LSR was calculated from sweat mass (0.80 ± 0.31 g), patch surface area (11.9 cm²), and duration (62 ± 14 min). Sweat [Na⁺], [Cl⁻], and [K⁺] were measured via ion chromatography.

Results

Based on the analysis of variance results, there were no differences between tattooed and non-tattooed skin for LSR (1.16 ± 0.52 vs. 1.12 ± 0.53 mg/cm²/min; p = 0.51), sweat [Na⁺] (60.2 ± 23.5 vs. 58.5 ± 22.7 mmol/L; p = 0.27), sweat [Cl⁻] (52.1 ± 22.4 vs. 50.6 ± 22.0 mmol/L; p = 0.31), or sweat [K⁺] (5.8 ± 1.6 vs. 5.9 ± 1.4 mmol/L; p = 0.31). Multiple regression analyses suggested that younger tattoos were associated with higher sweat [Na⁺] (p = 0.045) and colorful tattoos were associated with higher sweat [Cl⁻] (p = 0.04) compared with contralateral non-tattooed skin. Otherwise, there were no effects of LSR or tattoo characteristics on regression models for LSR or sweat electrolyte concentrations.

Conclusion

There were no effects of tattoos on LSR and sweat [K⁺] during exercise-induced sweating, but tattoo age and color had small effects on sweat [Na⁺] and sweat [Cl⁻], respectively.

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