title: Overspeed HIIT in Lower-Body Positive Pressure Treadmill Improves Running Performance.
abstract: OBJECTIVE
  Optimal high-intensity interval training (HIIT) regimens for running performance are unknown, although most protocols result in some benefit to key performance factors (running economy (RE), anaerobic threshold (AT), or maximal oxygen uptake (VO2max)). Lower-body positive pressure (LBPP) treadmills offer the unique possibility to partially unload runners and reach supramaximal speeds. We studied the use of LBPP to test an overspeed HIIT protocol in trained runners.
  
  
  METHODS
  Eleven trained runners (35 ± 8 yr, VO2max, 55.7 ± 6.4 mL·kg⁻¹·min⁻¹) were randomized to an LBPP (n = 6) or a regular treadmill (CON, n = 5), eight sessions over 4 wk of HIIT program. Four to five intervals were run at 100% of velocity at VO2max (vVO2max) during 60% of time to exhaustion at vVO2max (Tlim) with a 1:1 work:recovery ratio. Performance outcomes were 2-mile track time trial, VO2max, vVO2max, vAT, Tlim, and RE. LBPP sessions were carried out at 90% body weight.
  
  
  RESULTS
  Group-time effects were present for vVO2max (CON, 17.5 vs. 18.3, P = 0.03; LBPP, 19.7 vs. 22.3 km·h⁻¹; P < 0.001) and Tlim (CON, 307.0 vs. 404.4 s, P = 0.28; LBPP, 444.5 vs. 855.5, P < 0.001). Simple main effects for time were present for field performance (CON, -18; LBPP, -25 s; P = 0.002), VO2max (CON, 57.6 vs. 59.6; LBPP, 54.1 vs. 55.1 mL·kg⁻¹·min⁻¹; P = 0.04) and submaximal HR (157.7 vs. 154.3 and 151.4 vs. 148.5 bpm; P = 0.002). RE was unchanged.
  
  
  CONCLUSIONS
  A 4-wk HIIT protocol at 100% vVO2max improves field performance, vVO2max, VO2max and submaximal HR in trained runners. Improvements are similar if intervals are run on a regular treadmill or at higher speeds on a LPBB treadmill with 10% body weight reduction. LBPP could provide an alternative for taxing HIIT sessions.
authors.affiliation: 1Department of Sports Medicine, Stanford University School of Medicine, Stanford, CA; 2Sports Medicine, Department of Human Locomotion, Lausanne University Hospital (CHUV) and University of Lausanne, Lausanne, SWITZERLAND; 3Department of Orthopaedic Surgery, Human Performance Laboratory, Stanford University School of Medicine, Palo Alto, CA; and 4Clinical Pathophysiology, Department of Medicine, Lausanne University Hospital (CHUV) and University of Lausanne, Lausanne, SWITZERLAND.
authors.forename: Boris
authors.initials: B
authors.lastname: Gojanovic
authors.forename: Rebecca
authors.initials: R
authors.lastname: Shultz
authors.forename: Francois
authors.initials: F
authors.lastname: Feihl
authors.forename: Gordon
authors.initials: G
authors.lastname: Matheson
mesh_terms: D000328:Adult; D054874:Athletic Performance / Q000502:physiology*; D005080:Exercise Test / Q000379:methods*; D006339:Heart Rate; D006801:Humans; D008297:Male; D010101:Oxygen Consumption; D010806:Physical Education and Training / Q000379:methods*; D012420:Running / Q000502:physiology*