Table 1

 Body weight and serum sodium concentrations before and after the race in three groups of Ironman triathletes differing in their extent of weight loss during the race

VariableGroup 1Group 2Group 3
nMean (SD)RangenMean (SD)RangenMean (SD)Range
Group 1, weight loss exceeding 5%; group 2, weight loss of 3.5–4.5%; group 3, weight loss of 3% to a weight gain of 3%.
*Significantly different from registration weight (p<0.0001).
**Significantly different from starting weight (p<0.0001).
†Significantly different from group 1 (p<0.05).
††Significantly different from group 2 (p<0.05).
§Significantly different from group 1 and group 2 (p<0.001).
¶Significantly different from group 1 (p<0.001).
‡Significantly different from starting [Na+] (p<0.01).
Registration weight (kg)6474.9 (7.6)57.2–92.16974.5 (8.4)53.0–88.86875.5 (8.1)49.2–94.2
Starting weight (kg)8675.5 (7.8)*55.0–93.08675.5 (8.3)*52.8–91.88675.7 (8.0)50.0–94.4
Finishing weight (kg)8670.9 (7.6)**52.2–88.38672.5 (7.9)**50.7–88.48674.1 (7.8)† **48.6–91.7
Weight change (kg)86−4.6 (0.9)−8.0 to −3.086−3.0 (0.4)¶−3.6 to −2.186−1.6 (0.9)§−2.7 to +3.0
Weight change (%)86−6.2 (1.1)−10.7 to −5.086−3.9 (0.28)¶−4.5 to −3.586−2.1 (1.1)§−2.9 to +3.7
Starting [Na+] (mmol/l)56141.2 (1.7)135.2–144.366140.5 (1.5)136.4–144.157140.5 (1.6)†136.7–144.0
Finishing [Na+] (mmol/l)69142.4 (3.1)‡134.1–152.057141.3 (2.4)134.2–147.261139.8 (2.9)¶††125.8–145.0