Actually, strenuous physical activities are becoming increasingly popular around the world. In recent years, more athletes have become involved in ultraendurance races, such as the ironman triathlon, the 100 km race, and longer races performed in various days. Previous studies have examined the organic response in endurance running, swimming, triathlon, kayaking and cycling races. These results can be used to program training interventions, recovery times between probes, and nutritional and/or ergonomic strategies in ultraendurance events. Transferrin and iron levels presented high values related to an overstimulation of the liver, a normal renal function, a tendency to decrease flexibility, and an increase in aerobic capacity, finding a tendency to increase the absolute maximal oxygen uptake (37.2 ☒.4 versus 38.7 ± 1.8 mL/min) in contrast to previous studies conducted with subjects with similar age. Testosterone presented a decrease tendency (4.2 ± 2.5 versus 3.9 ± 2.6 ng/L) in opposition to the increase tendency of cortisol and ammonium parameters. After the race, participants presented a significant decrease in Hb (167.8 ± 9.5 versus 141.6 ± 15.7 mg/dL), strength (29.4 ± 2.7 versus 25.5 ± 3.7 cm in a countermovement jump), and oxygen uptake and heart rate at ventilatory threshold (1957.0 ± 458.4 versus 1755.2 ± 281.5 mL/kg/min and 140.0 ± 9.7 versus 130.8 ± 8.3 bpm, resp.). Selected biochemical, leg strength, flexibility, and aerobic capacity parameters were analyzed in 6 subjects 5 days before and 5 days after completing a 1700 km ultraendurance cycling race. The purpose of the present research was to study the organic response after ultraendurance cycling race.