Trail Runners Cannot Reach V˙O2max during a Maximal Incremental Downhill Test

• Published in: Medicine and science in sports and exercise 2020-05, Vol.52 (5), p.1135-1143
• Main Authors: LEMIRE, MARCEL, HUREAU, THOMAS J., REMETTER, ROMAIN, GENY, BERNARD, KOUASSI, BLAH Y. L., LONSDORFER, EVELYNE, ISNER-HOROBETI, MARIE-EVE, FAVRET, FABRICE, DUFOUR, STÉPHANE P.
• Format: Article
• Language: English
• Subjects: Biomechanical Phenomena; Exercise Test - methods; Humans; Lower Extremity - physiology; Muscle Strength; Oxygen Consumption; Physical Endurance - physiology; Running - physiology; Stress, Mechanical
• ISSN: 0195-9131; 1530-0315
• DOI: 10.1249/MSS.0000000000002240

PURPOSEThe purpose of this study was twofold(i) determine if well-trained athletes can achieve similar peak oxygen uptake (V˙O2peak) in downhill running (DR) versus level running (LR) or uphill running (UR) and (ii) investigate if lower limb extensor muscle strength is related to the velocity at V˙O2peak (vV˙O2peak) in DR, LR, and UR. METHODSEight athletes (V˙O2max = 68 ± 2 mL·min·kg) completed maximal incremental tests in LR, DR (−15% slope), and UR (+15% slope) on a treadmill (+1, +1.5, and +0.5 km·h every 2 min, respectively) while cardiorespiratory responses and spatiotemporal running parameters were continuously measured. They were also tested for maximal voluntary isometric strength of hip and knee extensors and plantar flexors. RESULTSOxygen uptake at maximal effort was approximately 16% to 18% lower in DR versus LR and UR (~57 ± 2 mL·min·kg, 68 ± 2 mL·min·kg, and 70 ± 3 mL·min·kg, respectively) despite much greater vV˙O2peak (22.7 ± 0.6 km·h vs 18.7 ± 0.5 km·h and 9.3 ± 0.3 km·h, respectively). At vV˙O2peak, longer stride length and shorter contact time occurred in DR versus LR and UR (+12%, +119%, −38%, and −61%, respectively). Contrary to knee extensor and plantar flexor, hip extensor isometric strength correlated to vV˙O2peak in DR, LR, and UR (r = −0.86 to −0.96, P < 0.05). At similar V˙O2, higher heart rate and ventilation emerged in DR versus LR and UR, associated with a more superficial ventilation pattern. CONCLUSIONSThis study demonstrates that well-trained endurance athletes, accustomed to DR, achieved lower V˙O2peak despite higher vV˙O2peak during DR versus LR or UR maximal incremental tests. The specific heart rate and ventilation responses in DR might originate from altered running gait and increased lower-limb musculotendinous mechanical loading, furthering our understanding of the particular physiology of DR, ultimately contributing to optimize trail race running performance.