This study was designed to investigate if monitoring of stress and recovery may be useful to detect overreaching in its early stages and may be used to evaluate effects of changes in training load. Nine swimmers were applied the Recovery-Stress Questionnaire for Athletes (RESTQ-Sport) in four different occasions (M1, M2, M3, M4) along a 6-week training period prior to a competition. During the basal training period (M1), recovery scales scored higher than stress scales, being the scales General well-being, Social recovery and Being in shape those reaching higher scores. Following the measure corresponding to the second training period (M2), in which training volume reached a maximum, there were significant increases in two stress scales (Injury and Emotional exhaustion), and decreases in three recovery scales (Success, Physical recovery, and Self-efficacy). Values increased again and did not significantly differ from those corresponding to the first measure during measures M3 and M4, in which there was a decrease in training volume and training time. Only a recovery scale score (Success) increased significantly from period M2 to period M4. When the recovery-stress (total recovery - total stress) state was calculated, it was found that there was a significant decreases in M2, and values progressively increased in measures M3 and M4, with no significant difference from M1. Results obtained indicate that the RESTQ-Sport is able to show significant changes concurrently with training loads. Regular monitoring of stress and recovery by these measures may help to detect overreaching in its early stages.