Individualized Endurance Training Based on Recovery and Training Status in Recreational Runners

Purpose Long-term development of endurance performance requires a proper balance between strain and recovery. While responses and adaptations to training are highly individual, this study examined whether individually-adjusted endurance training based on recovery and training status would lead to greater adaptations compared to a predefined program. Methods Recreational runners were divided into predefined (PD, n = 14) or individualized (IND, n = 16) training groups. In IND, the training load was decreased, maintained or increased twice a week based on nocturnal heart rate variability, perceived recovery, and heart rate-running speed index. Both groups performed three-week preparatory, six-week volume and six-week interval periods. Incremental treadmill tests and 10 km running tests were performed before the preparatory period (T0) and after the preparatory (T1), volume (T2), and interval (T3) periods. The magnitude of training adaptations was defined based on the coefficient of variation between T0 and T1 tests (high >2 x, low