Abstract / Summary
Objective: The objective was to compare acute cardiorespiratory, metabolic, perceptual, and internal training load (ITL) responses to four endurance exercise protocols in sedentary college students. Methods: Forty-five participants entered a crossover repeated-measures study involving High-Volume Low-Intensity Training (HVT), Pyramidal Training (PYT), High-Intensity Interval Training (HIIT), and Threshold Training (THR). Cardiac load, respiratory-metabolic and energy-expenditure responses, perceptual responses, and ITL were assessed. Results: For cardiac responses, THR elicited the highest HRmean, whereas HIIT produced the highest HRpeak, with significant differences between THR and HIIT (p = 0.032 and p = 0.003, respectively). For respiratory-metabolic responses, HIIT and THR generally showed greater ventilatory responses than HVT, while THR produced the highest VO2 and VCO2. For energy metabolism, HIIT elicited the highest EMR, METs, and TEE, with significant between-condition differences (p < 0.05). Condition-specific regression models showed that HR explained 57.4–67.3% of EMR variance, VE explained 39.9–44.6%, and HR explained 52.7–58.6% of VE variance (all p < 0.001). For perceptual responses and internal load, THR produced the highest TRIMP. HIIT elicited the highest RPE and s-RPE, and HVT showed the most favorable FS response. Conclusions: HVT and PYT may be more suitable as introductory or progressive exercise options for sedentary college students with lower exercise tolerance, whereas THR may be preferable for sustained cardiovascular stimulation and HIIT for a more time-efficient, higher metabolic stimulus in individuals able to tolerate greater exercise stress.