PRE-to-POST changes of R/h and Z/h were positively related to racing time (r = 0.80, p = 0.01) and internal workload (r = 0.80, p ≤ 0.02). Besides, basal R/h and Z/h were positively related to PRE-to-POST changes of R/h and Z/h (r = 0.80 p = 0.009). Racing time was positively related to basal resistance -R/h- (r = 0.68 p = 0.04) and bioimpedance -Z/h- (r = 0.68 p = 0.045). Compared to PRE, POST48h values reflected fluid retention by changes in BIVA, while BM was still lower (p = 0.0001). Increased hydration status from POST to POST48h was suggested by a reversed vector migration and increased BM (p = 0.0001). Vector migration in POST indicated dehydration, paralleled by a decrease in BM (p = 0.0001). Bioimpedance vector analysis (BIVA) showed triathletes’ vectors placed to the left of the major axis and mostly outside the 50% tolerance ellipse of the reference population. Anthropometric and bioelectrical assessments were performed before (PRE), after (POST), and 48 hours following the race (POST48h). This study aimed to provide the first description of the whole-body bioimpedance vector of nine non-professional triathletes, and to assess body mass (BM) and vector variations evoked by an ultra-endurance triathlon event.
