Development and validation of a 1-km cardio-trekking test to estimate cardiorespiratory fitness in healthy adults

•This is the first study that examined the prediction of maximal oxygen uptake with an outdoor hiking test including a natural slope.•We transferred a maximal laboratory test to a submaximal field test.•The project aimed to appreciate natural and safe cardio-trekking trails for the sustainable promotion of cross-generational and health-oriented tourism.•The calculated predictive model achieved similar predictive power compared to previously published work.