Author(s): BELTRAMI, F., Institution: ETH ZURICH: EIDGENOSSISCHE TECHNISCHE HOCHSCHULE ZURICH, Country: SWITZERLAND, Abstract-ID: 2807

INTRODUCTION:
Running economy (RE) is a key determinant of distance running performance and is commonly assessed under controlled conditions, often on treadmills. Track running offer an improvement in ecological validity compared to treadmill-based testing, however it remains unclear whether track-based assessments can be generalized to road running, where surface properties and geometry differ. In addition, footwear and running speed may interact with running surface and influence physiological and gait responses. Therefore, the aim of this study was to compare RE and selected spatiotemporal variables between track and road running under real-world conditions, and to examine whether footwear and running speed modulate potential surface-related differences.

METHODS:
Seventeen recreational runners (13 men, 4 women, age 32 ± 8 years old, weight 71 ± 6 kg, height 173 ± 6 cm, V?O2peak 53.5 ± 4.6 ml·min-1·kg-1) performed overground running trials on 400-m athletics track and an adjacent concrete loop at two submaximal running speeds, one below and above above the first ventilatory threshold. Participants performed a single 5-6 min run at each speed and surface condition, once wearing an own pair of standard running shoes and once wearing own advanced footwear technology (AFT) shoes. Throughout the runs, gas exchange, heart rate and spatiotemporal variables were assessed. Statistical equivalence for track values was set at a threshold of plus or minus 2% from road-based values.

RESULTS:
O2 cost was 0.75 ± 1.12% higher (95% CI: 0.2 to 2.6 ml·kg-1·km-1, p = 0.024) during road compared with track running, with a significant shoe x surface interaction (p = 0.026). RE during track running was improved when wearing standard shoes (p = 0.038) but not AFT (p = 0.522). Equivalence between track and road running was demonstrated for AFT shoes at both running speeds, whereas equivalence could not be established for standard shoes, although observed differences were small and the upper limits close to the predefined equivalence bounds (2.2% for the fast speed and 2.3% for the slow speed vs 2% predefined limits). Small but systematic environment-related differences were observed, with higher cadence and lower dynamic instability during track running, independent of footwear. Ground contact time and impact magnitude remained comparable across surfaces.

CONCLUSION:
RE and related physiological responses were largely comparable between track and road running in trained runners. However, the practical equivalence between surfaces depended on footwear, with equivalence demonstrated only when AFT shoes were worn. These findings suggest that track-based assessments provide a useful framework for evaluating RE and footwear effects, but their generalization to road running should be interpreted with consideration of shoe–surface interactions.