Author(s): YUCELSOY, B., SOZEN, H., ACAR, S.T., OLMEZ, C., Institution: FACULTY OF SPORTS SCIENCES, Country: TURKEY, Abstract-ID: 2249

INTRODUCTION:
Ventilatory efficiency represents a critical component of cardiopulmonary performance, reflecting the interaction between ventilatory control, pulmonary gas exchange, and cardiovascular oxygen delivery. Although submaximal exercise testing is widely used in both performance and clinical settings, the coordinated behavior of ventilatory and cardiovascular efficiency indicators across discrete low-to-moderate workload stages remains incompletely characterized. This study aimed to investigate the effects of progressively increasing submaximal cycling workloads on ventilatory responses, cardiovascular dynamics, and ventilatory efficiency parameters.
METHODS:
Eighteen healthy adults (6 females, 12 males; 19.50±1.43 years) completed a staged cycling protocol consisting of four consecutive workloads (25, 50, 75, and 100 W), each maintained long enough to achieve physiological steady-state responses. Ventilation (VE), heart rate (HR), ventilatory efficiency (VE/VCO₂), end-tidal CO₂ (PetCO₂), and oxygen pulse (VO₂/HR) were continuously measured using a portable breath-by-breath metabolic analysis system. For each workload stage, the final steady-state interval values were averaged for analysis. Differences between workload stages were evaluated using repeated-measures ANOVA with Bonferroni-adjusted post-hoc comparisons, and effect sizes were expressed as partial eta squared (η²p).
RESULTS:
Increasing workload elicited significant progressive increases in VE (F(3,51)=205.11, η²p=.923), HR (F(3,51)=97.58, η²p=.852), VO₂/HR (F(3,51)=120.94, η²p=.877), and PetCO₂ (F(3,51)=41.69, η²p=0.710) (p<.001), indicating coordinated ventilatory and cardiovascular adjustments to rising metabolic demand. In contrast, VE/VCO₂ decreased significantly across workload stages (F(3,51)=29.65, η²p=.636), with post-hoc analyses showing no significant difference between 75 and 100 W, suggesting a plateau response at higher submaximal intensities.
CONCLUSION:
Progressive submaximal workload increments induce tightly synchronized ventilatory and cardiovascular responses while improving ventilatory efficiency predominantly at low-to-moderate intensities, followed by a plateau at higher submaximal workloads. These findings demonstrate that staged submaximal protocols provide a sensitive and physiologically informative approach for detecting cardiopulmonary efficiency dynamics, supporting their utility in both performance monitoring and applied physiological assessment.