Author(s): MELLO, D., CUNHA, M.G., ROSA, G. , Institution: PHYSICAL EDUCATION COLLEGE OF THE BRAZILIAN ARMY , Country: BRAZIL, Abstract-ID: 287

INTRODUCTION:
Triathlon participation has increased, particularly among women. Sex differences are well established in single endurance sports but evidence in long-distance triathlon is still limited. This study aimed to evaluate physiological and hydration monitoring in a female triathlete preparing for an Ironman race.
METHODS:
Longitudinal case study in 2025 with an amateur female triathlete (39yrs, 161cm, 53kg) preparing to the Ironman Cozumel (Mexico, Nov 2025) and qualify for the Ironman World Championship in Kona, Hawaii (2026). Distinct training sessions was monitored across the season. First session (S1), in March, was a 60-km cycling on an urban route in São Paulo, Brazil (1h 50min). Second session (S2), in June, was an aquathlon comprising open-water swimming (1,860m; 53 min; Copacabana Beach, Rio de Janeiro, Brazil) followed by a 10-km run (50 min; pace 5:00 min·km⁻¹) along the coastal bike path. Third session (S3), in November, was a duathlon including cycling (86.8km; 2h 29min 42 s) on a road-cycle path and running (8.29 km; 36min 14s) in an outdoor park. Pre and post each training session, environmental conditions (air temperature (Ta) and relative humidity (URA)), core (Tcore) and skin temperature (Tskin) (CoreTemp®), hydration status (Hyd) via salivary osmolarity (MX3®), muscle oxygen saturation (SmO₂) (Moxy®), blood lactate (Lac) (Roche®), hemoglobin (Hb) and hematocrit (Hct) (Hemochromax®) were assessed. Total water intake and sports drink (Liquidz®; 6-g sticks containing 374 mg sodium, 64 mg potassium, and 216 mg magnesium) were recorded. Across all sessions, the nutritional strategy consisted primarily of water ad libitum, Liquidz®, and carbohydrate gels (30 g).
RESULTS:
In S1, Tcore increased from 37.16°C to 38.93°C, and Tskin from 32.37°C to 34.34°C. Normal Hyd (22 to 56 mOsm). SmO₂ increased (58% to 84%), Lac decreased (3.8 to 2.8 mmol·L⁻¹), Hb slightly decreased (14.6 to 14.4 g·dL⁻¹), and Hct (46.5% to 43.2%). In S2, Tcore (37.1 to 37.3 °C), Tskin decreased (33.22°C to 31.65°C). Mild dehydration (77 to 81 mOsm), SmO₂ rose (54.8% to 88.1%), Lac increased (2.2 to 2.7 mmol·L⁻¹), Hb increased (13.5 to 14.4 g·dL⁻¹), and Hct (40.5% to 43.2%). In S3, the greatest thermal stress was observed, with Tcore 37.35 °C to 39.62 °C and Tskin from 32.94 °C to 33.93 °C. Normal Hyd (29 to 28 mOsm). SmO₂ increased (39.4% to 71.9%), Lac (4.4 to 4.5 mmol·L⁻¹), Hb decreased (12.5 to 11.4 g·dL⁻¹) and Hct (37.5% to 34.2%). In S1, thermoneutral (Ta 22-24.7°C; URA 81-71%); S2 thermal stress (Ta 24.0-28.0°C; URA 77-70%); S3, cooler conditions (Ta 17.7-19.7°C; URA 75-64%).
CONCLUSION:
Integrated monitoring revealed high thermal sensitivity during cycling, and the individualized hydration and thermoregulation strategies proved effective, allowing safe throughout training. The athlete placed 1st (35–39 age group), finished in 10:05:49, ranked top 19 of 255 women, and qualified for Kona. Supported by LIQUIDZ®, CoreTemp®, MX3®, Moxy® and Kovalent®.