The Effects of Incline and Level-grade High-intensity Interval Treadmill Training on Running Economy and Muscle Power in Well-trained Distance Runners

Despite a paucity of evidence, uphill running has been touted as a sport-specific resistance-to-movement training tactic capable of enhancing metabolic, muscular, and neuromuscular processes in distance runners in ways similar to previously established resistance-to-movement training methods, such as heavy and/or explosive strength training and plyometric training. Therefore, the purpose of this investigation included documenting the effects of incline and level-grade interval treadmill training on indices of running economy (RE) (i.e., oxygen consumption [V_ O2] and blood lactate [BLa] responses of submaximal running) and muscle power. Thirty-two well-trained distance runners (age, 27.4 6 3.8 years; body mass, 64.8 6 8.9 kg; height, 173.6 6 6.4 cm; and V_ O2max, 60.9 6 8.5 ml$min21$kg21) received assignment to an uphill (GHill = 12), level-grade (GFlat = 12), or control (GCon = 8) group. GHill and GFlat completed 12 interval and 12 continuous run sessions over 6 weeks, whereas GCon maintained their normal training. Dependent variables measured before and after training were V_ O2 and BLa at 2 separate velocities associated with lactate threshold (VLT) (V_ O2-60% and V_ O2- 80%; and BLa-60% and BLa-80%, respectively); percentage of V_ O2max at lactate threshold (%V_ O2max at VLT); muscle power as assessed through a horizontal 5-jump test (5Jmax); and isokinetic knee extension and flexion at 3 angular velocities (90, 180, and 3008$s21). Statistical significance was set to p # 0.05. All groups significantly improved 5Jmax, V_ O2-60%, V_ O2-80%, BLa-60%, and BLa-80%. Additionally, GHill and GFlat significantly improved %V_ O2max at VLT. Other indices of RE and muscle power did not improve. We conclude incline treadmill training effective for improving the components of RE, but insufficient as a resistance-to-movement exercise for enhancing muscle power output