Author(s): PAPALE, O., FESTINO, E., DI ROCCO, F., CORTIS, C., FUSCO, A. , Institution: UNIVERSITY OF CASSINO AND LAZIO MERIDIONALE, Country: ITALY, Abstract-ID: 1300

Cardiorespiratory fitness is a key determinant of exercise tolerance during hiking activities and represents a relevant parameter to consider when selecting routes appropriate to individual capacity. In parallel, exercise tolerance, also understood as fatigability, seems to complete the evaluation of physiological profile of the hikers, emerging from the integration of cardiovascular strain and perceived effort experienced during exercise. Therefore, the purpose of the present study was to examine the association between cardiorespiratory fitness and fatigability during an outdoor hiking session with potential implications for individualized route selection and effort self-monitoring.
Twenty-four physically active adults (age: 24.9 ± 0.6 years; BMI: 23.5 ± 2.6 kg/m2) participated in the study. Theoretical maximum heart rate (HRmax) was calculated for each participant, according to the equation 220 - age (years). Cardiorespiratory fitness was assessed by means of the Ruffier test following the standard protocol [1]. Participants then completed an outdoor hiking session, during which heart rate was continuously monitored, while Rating of Perceived Exertion (RPE) was collected every 10 minutes on a CR 0 – 10 scale. Fatigability was calculated as a psychophysiological index by multiplying the highest heart rate (bpm) reached during the session by the RPE value recorded at the end of the same 10-minute interval in which that heart rate occurred. Pearson's correlation coefficient was used to assess the relationship between fatigability and the Ruffier index. Statistical significance was set at p < 0.05.
During the outdoor session (length: ~3800 m; maximum slope: 19%; mean slope: 5.3%), participants exercised for approximately 40 minutes, reaching on average 67% of their theoretical HRmax (131.3 ± 19.4 bpm). The session was rated as low-to-moderate based on RPE values (2.2 ± 0.9 pts). A strong negative correlation (r = -0.84) was observed between fatigability (294.4 ± 163.2 AU) and Ruffier index (12.3 ± 0.9).
The present findings indicate that cardiorespiratory fitness is strongly associated with fatigability during an outdoor hiking task. Individuals with lower Ruffier index values exhibited reduced psychophysiological stress, suggesting a more efficient integration between cardiovascular response and perceived effort during the task. These results support the use of simple field-based fitness assessments, such as the Ruffier test, as potential tools for predicting individual tolerance to prolonged outdoor activities. From a physical activity promotion perspective, combining a simple fitness test with perceived effort monitoring may support self-regulation of intensity and safer participation in outdoor activities. Moreover, the combined use of heart rate and RPE to quantify fatigability may represent a practical approach for monitoring effort and recovery in real-world hiking and endurance contexts.

[1] Zanevskyy I. et al. (2017) J Test Eval 45:2193