Adaptive gait transition in trekking pole-assisted hiking due to fatigue and staircase height elevation.

Humans adapt their gait patterns in response to both internal (e.g., fatigue) and external (e.g., terrain) constraints. Although bipedal locomotion is generally efficient, its stability is reduced on steep or uneven surfaces. Under such conditions, adult hikers often use trekking poles to enhance stability and reduce physical load. In this study, we analysed pole-foot coordination in novice hikers ascending a 4.2 km uphill trail using a gait-classification framework derived from quadrupedal locomotion research. Coordination patterns were characterised by duty factor and diagonality, and gait transition was defined as a shift in the dominant diagonality range across stair-height conditions. When participants ascended moderately high stairs (20 cm), diagonal couplets (diagonality ranges of 40%-50% and 50%-60%) were most frequently observed. These patterns accounted for 36.7% of all steps recorded at 20 cm stairs in the early section of the trail and were similarly frequent (43.4%) in the later section. In contrast, when the stair height increased to approximately 40 cm, lateral couplets (diagonality ranges of 0%-10% and 90%-100%) became dominant, accounting for 33.9% of all steps recorded under this condition. These results indicate that hikers preferentially select pole-foot coordination patterns depending on stair height and show that a diagonal-lateral classification scheme provides a useful basis for describing qualitative coordination transitions in human pole-assisted gait.