Validity of a wearable sweat rate monitor and routine sweat analysis techniques using heat acclimation

• Published in: Journal of thermal biology Vol. 90; pp. 102577 - 8
• Main Authors: Relf, Rebecca, Eichhorn, Gregor, Waldock, Kirsty, Flint, Melanie S., Beale, Louisa, Maxwell, Neil
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.05.2020; Elsevier BV
• Subjects: Acclimation; Acclimatization - physiology; Adolescent; Adult; Body mass; Chest; Exercise - physiology; Female; Forearm; Heat; Heat stress; Hot Temperature; Humans; Hyperthermia; Male; Middle Aged; Monitoring, Physiologic - instrumentation; Relative humidity; Short-term heat acclimation; Sodium chloride; Sudomotor function; Sweat; Sweat analysis; Sweating; Validity; Wearable Electronic Devices; Young Adult; Validity; Sweat analysis; Short-term heat acclimation; Heat stress; Sudomotor function
• ISSN: 0306-4565; 1879-0992
• DOI: 10.1016/j.jtherbio.2020.102577

the aim of this study was to assess the validity of a novel wearable sweat rate monitor against an array of sweat analysis techniques which determine sudomotor function when exercising moderately under heat stress. Construct validity was determined utilising a 5-day short-term heat acclimation (STHA) intervention. Nineteen healthy individuals (age: 41 ± 23 years, body mass: 74.0 ± 12.2 kg, height: 174.9 ± 6.9 cm) [male; n = 15, female; n = 4] completed nine trials over a three-week period, in a controlled chamber set to 35 °C, 50% relative humidity for all sessions. The pre and post-trials were separated by five consecutive controlled hyperthermia HA sessions. Sweat analysis was compared from pre and post-trial, whereby whole body sweat rate (WBSR) was assessed via pre and post nude body mass. Local sweat rate (LSR) was determined via technical absorbent patches (TA) (weighed pre and post) and a novel wearable KuduSmart® (SMART) monitor which was placed on the left arm during the 30-min of exercise. Tegaderm patches, used to measure sweat sodium chloride conductivity (SC), and TA patches were placed on the back, chest and forearm for the 30-min cycling. Sudomotor function significantly adapted via STHA (p < 0.05); demonstrated by a WBSR increase of 24%, LSR increase via the TA method (back: 26%, chest: 45% and arm: 48%) and LSR increase by the SMART monitor (35%). Finally, SC decreased (back: -21%, chest: -25% and arm: -24%, p < 0.05). All sweat techniques were sensitive to sudomotor function adaptation following STHA, reinforcing their validity. The real time data given by the wearable KuduSmart® monitor provides coaches and athletes instant comparable sudomotor function feedback to traditional routinely used sweat analysis techniques. •First study to investigate validity of a novel wearable sweat rate monitor when exercising under heat stress.•Routinely used sweat techniques are valid.•Novel wearable sweat monitor is valid and user friendly.•STHA induced large sweat adaptations using an isothermic model.