Multidimensional Adaptations to Fartlek and Interval Training in Volleyball Players: An Integrated Analysis of Physiological, Biochemical, and Perceptual Responses
Asha Devi T, Uma VEERAPPAN, Suresh Kumar MADHAVAN · Studia Universitatis Babeş-Bolyai Educatio Artis Gymnasticae · 2026
Background: Monitoring training adaptation in volleyball requires an integrated evaluation of physiological, biochemical, and perceptual responses; however, previous studies have largely examined these variables in isolation, limiting understanding of their combined contribution to internal training load.
Objective: This study aimed to examine the effects of Fartlek training and interval training on functional (VO₂max, heart rate recovery), biochemical (blood lactate, creatine kinase), and perceptual (sRPE, mRPE) variables, and to determine their collective influence on internal training load.
Methods: A randomized controlled experimental
Design: was employed with 60 male volleyball players (aged 18–25 years) assigned to Fartlek (n = 20), interval (n = 20), and control (n = 20) groups. The intervention lasted eight weeks (3 sessions/week). Data were analyzed using repeated-measures ANOVA, Pearson correlation, and multiple regression, with effect sizes reported using Cohen’s d and η².
Results: Both training groups showed significant improvements in VO₂max and heart rate recovery (p < .001), along with significant reductions in blood lactate and creatine kinase (p < .05–.001). Training load indicators (sRPE and mRPE) increased significantly in both groups, reflecting enhanced load tolerance. Regression analysis revealed that functional and biochemical variables collectively explained a substantial proportion of variance in internal load (R² = .62, p < .001), with VO₂max and HRR emerging as the strongest predictors. Effect size analysis indicated large to very large magnitudes across all variables (η² = .65–.96).
Conclusion: Fartlek and interval training induce significant multidimensional adaptations, highlighting the importance of integrating physiological, biochemical, and perceptual indicators for effective training load monitoring. These
Findings: contribute to advancing multidimensional assessment approaches in sports training and performance optimization. Article history: Received 2026 July 23; Revised 2026 September 02; Accepted 2026 September 04; Available online 2026 September 30; Available print 2026 September 30