Energetic and neuromuscular impact of running on even or uneven surfaces in standardized laboratory conditions

Purpose: We examine the energetic and neuromuscular effects of running on even (E-T) and uneven terrains (UE-T) by creating smooth and rough conditions on a standardized circuit. Methods: Ten adults (age 32.1 ± 7.6 years, body mass 62.2 ± 7 kg, height 167.5 ± 4.2 cm) ran on an 'iterative-8-shaped' path. For UE-T, solid hemispheres were fixed to a perforated mat, while for E-T, visible marks guided foot placement. Participants performed two 6-min trials on both terrains in a counterbalanced order, maintaining consistent running patterns and low-intensity speed with a metronome to guide step frequency. This ensured consistency in the timing and positioning of foot placement between the two conditions. Cardio-metabolic parameters were measured continuously, and muscle activation was recorded from six leg muscles using surface EMG. Results: The analysis showed significantly higher cardio-metabolic responses in UE-T compared to E-T, with increases in oxygen cost (+18 %), energy cost (+23 %), respiratory frequency (+7%), ventilation (+19 %), heart rate (+10 %), and RPE (+50 %) (all p < 0.05). Electromyographic activation of the tibialis anterior (+22 %) and peroneus longus (+10 %) also increased in UE-T. Conclusions: These findings indicate that running on uneven terrain demands more energy and greater activation of ankle stabilizers, as required in off-road and trail running.