Introduction The purpose of this study was to assess nutritional status of swimmers, during the marathon swimming event of crossing Toroneos (26 km). The participants were 24 athletes mean aged 36.08±12.52 years. The sample was divided into two groups, according to their age: (1) 18–34 years (12 athletes) and (2) 35–68 years (12 athletes).

Methods The athletes recorded their food intake for 3 training days and during the race. Food intake was analysed in nutrients using the Food Processor nutrition program (version 7.4, 1997, ESHA Research Salem, Oregon). For the statistical analysis, SPSS (v.15) was used.

Results The athletes had inadequate intake of energy during the training period. There were no differences in energy intake, according to age (2144±190 kcal for the athletes aged 18–24 years and 2181±198 kcal for the athletes aged 35–68 years). Both groups had inadequate intake of carbohydrates (4.6±0.96 g/kg body weight or 67.55±10.74% of energy intake, for the younger athletes and 4.0±1.21 g/kg BW or 68.44±9.16% of EI for the older athletes). Protein intake was 0.95±0.20 g/kg BW or 14.30±4.46% of EI, and 0.93±0.31 g/kg BW or 15.71±3.81% of EI for the younger and the older athletes, respectively. Fat intake was above the recommended values for both age groups (18–34 years: 32.70±2.60% of EI, 35–68 years: 35.13±3.10% of EI). Both groups met the recommended daily allowances (RDA) for all micronutrients, with the exception of B₃, Zn and Mn.

During the race, the athletes consumed 12 types of solid food and 7 types of fluids. The preferred foods were: bananas, energy gel and honey. From liquid beverages the preferred ones were: isotonic drinks, water and soft type cola. Energy intake during the race was 1048±447 kcal for the younger group and 948±504 kcal for the older group. There was no difference between the two groups in energy intake. Younger athletes maintain a stable body weight, while older ones lost 1.62±1.89 kg, during the race.

Conclusion The athletes had insufficient energy and carbohydrate intake, factors that can influence their athletic performance. There was no significant difference between the two groups in energy and macronutrient intake. However, the older athletes had higher demands during the race in energy and nutrients, due to their higher energy expenditure, as the duration of the race was longer for them and lead to a loss of body weight.