Author(s): CELIE, B., CARPENTIER, M., DIEDRICH-ARMAND, M., RABINEAU, J., FAORO, V., Institution: UNIVERSITÉ LIBRE DE BRUXELLES, Country: BELGIUM, Abstract-ID: 2502

INTRODUCTION:
Different training modalities are traditionally used in endurance sports to maximize performance, including moderate-intensity continuous training (MICT) and interval-based methods such as high-intensity interval training (HIIT) or Sprint Interval Training (SIT). Few recent studies have shown that Self-Paced interval training could be of added value to the sports specific literature and practice. The aim of this study was to evaluate the effects of a 12-week self-paced high-intensity interval running program on VO₂max, lactate thresholds, and ventilatory thresholds. Additionally, the study examined the influence of training adherence and mean session intensity on physiological adaptations.
METHODS:
Twenty moderately active adults (10 men, 10 women) participated in this study. Pre- and post-intervention assessments included DXA body composition analysis and a graded treadmill exercise test measuring VO2peak and lactate tresholds. The 12-week training program consisted of three weekly running sessions: two self-paced high-intensity interval sessions and one low-intensity endurance session. Exercise intensity was self-regulated but retrospectively monitored using heart rate and ratings of perceived exertion. Statistical analyses were performed using paired t-tests, and Pearson correlation testing, or Wilcoxon and Searman correlation tests depending whether normality was guaranteed.
RESULTS:
VO₂peak values (p < 0.001) and the anaerobic threshold (p = 0.04) significantly increased after 12 weeks of self-paced training while the aerobic treshold did not evolve significantly. Anthropometric indices such as fat mass significantly decreased (−4.7%, p = 0.021), while lean body mass percentage slightly increased (+0.96%, p = 0.03). No significant correlations were found between changes in peak VO₂ and mean training intensity (p = 0.416) or adherence (p = 0.776).
CONCLUSION:
A 12-week self-paced high-intensity interval training program can induce significant improvements in cardiorespiratory fitness and body composition, even without strict intensity prescription. The absence of correlations between physiological adaptations and mean intensity or adherence suggests a complex and individualized training response, in which perceived exertion and other factors may play a key role. This training modality may represent a practical and effective alternative in autonomous training or reconditioning contexts.