Back pain is common among elite cyclists. Experiences of athletes and observations of coaches show that it may influence training quality and sometimes even limit performance during competition. Therefore the following study questions were investigated: 1) How many athletes of the Swiss cycling national teams suffer back pain during training or competition? 2) How good is athletes’ core strength? 3) What correlation exists between back pain and core strength? 4) Does an intensified core strength training reduce back pain? A total of 111 elite cyclists, 45 athletes (38 m, 7f; 19.6 ± 3.5y) of technical disciplines (BMX, Trial, Downhill, 4X) and 66 athletes (39 m, 27f; 19.5 ± 5.8y) of endurance disciplines (road, MTB, Cyclo-cross) all members of Swiss cycling national teams, took part in in the study. They performed a core strength test, got an instruction session on core strength training, and filled out a standardized questionnaire on back pain at time of testing and after four months of ­training. 1) In Swiss elite cyclists back pain is frequent: In training every third suffers slight and every tenth rider moderate to heavy back pain. In competition roughly half of all riders are affected by back pain episodes, and 22.5% of all have moderate to heavy back pain impairing performance. 2) About one third of all elite cyclists has an insufficient core strength. 3) Having a good core strength of the dorsal muscle chain proved to be positively related to a lesser frequency of back pain. Whereas there was no such correlation between back pain and core strength of the ventral and lateral chain. 4) The 47.9% of athletes intensifying their core strength training during the four months period could significantly reduce their back pain in cycling, in competition, and in daily life.