Study design: Case study in handbiking under competition conditions. Objective: To investigate exercise-induced, metabolic, pulmonary, cardiovascular and energetic reactions of a paraplegic athlete during a city marathon. Setting: City marathon Cologne, Germany. Subject: We tested a 27-year-old male athlete from the German national team. The handicap of the athlete was a complete traumatic spinal cord injury ASIA/IMSOP Grade A at the level of the fourth thoratic vertebra (Th 4 ). Method: In the competition, the athlete used his own race handbike whose crank system had been exchanged for a power measurement system with registering option. For measuring ventilatory gas parameters during exercise, a portable spirometric system was used. The athlete managed to finish the marathon race in 1:48:54 h. Results: The mean oxygen uptake ( . VO 2 ) during the marathon was 1580 ml/min, with a maximum value of 2535 ml/min. The mean heart frequency was 137 bpm with a maximum of 157 bpm. During the race the mean energy consumption was 463 kcal/h with a maximum of 758 kcal/h. Prior to the race, the blood lactate value was 2.9 mmol/l; after 10 km 4.4 mmol/l; after 20 km 2.9 mmol/l, and after 30 km 2.9 mmol/l. Conclusion: Competition-oriented handbikers should concentrate on exercise units of long duration at low intensities -like marathon runners or cyclists -in order to improve their aerobic performance capacity. However, it has to be pointed out that paraplegic athletes develop relatively high metabolic intensities in competition and that the variability of their physiological parameters is considerably high.