The purpose of the study was to assess the effect of a three-day hike in the Ukrainian Carpathians on physical endurance indicators and its recreational effect among school pupils and university students. The participants were 120 young people (60 pupils and 60 students) who completed a three-day, 37 km route (Dilove village – Mount Pip Ivan – Dilove village), with elevations ranging from 350 m to 1,936 m above sea level. Functional status was assessed using the Harvard Step Test, the 12-minute Cooper test, continuous heart-rate monitoring, a Likert-scale questionnaire, and methods of mathematical statistics. After the hike, the Harvard Step Test Index increased significantly (p < 0.001), by 12.4% among pupils and 14.2% among students; the Cooper-test distance increased by 8.8% in both groups. Cardiorespiratory measurements recorded more economical effort among students, whose mean heart rate while walking was lower (134.2 ± 8.5 bpm compared with 138.4 ± 9.2 bpm among pupils) and whose pulse returned to 100 bpm sooner (p < 0.001). Load intensity correlated positively with gains in endurance (ρ = 0.74 among pupils and ρ = 0.69 among students), in keeping with a dose-dependent training effect. Subjective assessments likewise pointed to considerable recreational value: more than 88% of participants stated that they experienced psychological recovery, while 91.7% of pupils and 96.7% of students wished to repeat the hike. The practical importance of these results lies in the scientific justification of three- day mountain hikes as an effective way of strengthening physical education. The data may assist teachers and coaches in differentiating physical loads for different age groups, and specialists developing health-enhancement programmes aimed at reducing physical inactivity and improving young people’s cardiorespiratory function

adaptation; training effect; age differences; sex differences; cardiorespiratory system