Relaxing massages and playing music in stables may be used to mitigate the high level of stress in race horses. In the study, we compared effects of different frequencies of massages and different hours of music for race horses. Sixty horses were equally divided into one control group and four experimental groups. The experimental groups were treated with various relaxing methods: music for 1 hour a day, music for 3 hours a day, massage on the day preceding a race, and daily massage during the 6 months of the racing season. To evaluate the effects of the methods, horses' heart rate (HR) and parameters of heart rate variability (ratio of low to high frequencies of the power spectrum–LF/HF, and root mean square of successive beat-to-beat difference [RMSSD]) were measured while preparing horses for training sessions. Salivary cortisol concentrations were measured before and after training sessions. Official general handicap and success coefficient in the racing season were considered as performance parameters. In the experimental groups, lowered HR, LF/HF, and salivary cortisol concentrations as well as increased RMSSD were found, however, at various levels. The most positive changes in the parameters under study were found in horses massaged every day, which shows that relaxing massages are beneficial for horses' welfare and performance. Massages only about once every 3 weeks also gave some positive effects. It was shown that playing relaxing music for 3 hours a day had more positive effects on horses' emotional state than for 1 hour.