Immediate, Residual, and Cumulative Effects of Fartlek, Hill Circuit, and Roll-On Training in Long-Distance Runners (IRCT-LDR)

Long-distance running places substantial physiological and mechanical demands on athletes. Appropriate conditioning is therefore important for developing the capacity to tolerate training stress, recover effectively, and maintain or improve running performance. Different conditioning modalities may impose distinct physiological and mechanical demands, which may result in differences in immediate exercise responses, post-exercise recovery, training load, and longer-term adaptation.

This randomized controlled trial will compare three conditioning modalities. Fartlek training, hill circuit training, and roll-on training in well-trained long-distance runners. Twenty-one eligible runners will be randomly allocated to one of three parallel training groups: the Fartlek Training Group, Hill Circuit Training Group, or Roll-On Training Group. Each group will complete its assigned conditioning modality for 12 weeks, comprising 24 prescribed training sessions.

The study will examine three dimensions of response to conditioning. Immediate responses will include physiological and perceptual responses measured during or immediately after training. Residual responses will focus on recovery-related responses during the 24 hours following conditioning sessions. Cumulative responses will examine changes that develop over repeated exposure to the training intervention, including changes in running performance and aerobic fitness.

Repeated measurements will be collected throughout the intervention to characterize responses to the three conditioning modalities. Measures will include heart rate, blood lactate concentration, rating of perceived exertion, delayed-onset muscle soreness, recovery and wellness indicators, internal training load, 5-km time-trial performance, and VO₂max. Training-load measures will be derived from session rating of perceived exertion and session duration and will be used to characterize the training demands accumulated during the intervention.

The study will compare the response patterns among the three intervention groups to determine whether Fartlek, hill circuit, or roll-on training produces different immediate, residual, and cumulative responses in well-trained long-distance runners. The findings are intended to contribute evidence for the selection and progression of conditioning modalities while considering training stimulus, recovery, and performance-related responses.