That was more because they were heavily doped up on EPO. Back in the early days of the drug's use in cycling, the team doctors and other folks hadn't figured out the safe dosages yet plus everyone wanted to push it as far as they could go. They'd shoot up so much EPO that all the extra red blood cells turned their blood into syrup, and when the athletes were sleeping and their blood wasn't circulating fast enough it would clot up and kill them dead. Some of the teams had their athletes wearing heart rate monitors to bed, if their heart beat went below a certain rate while sleeping the alarms would go off and they'd have to get up and do sprints to get their blood flowing again before they dropped dead. Those were some crazy times in the sport.