title: Effects of intensity and duration in aerobic high-intensity interval training in highly trained junior cross-country skiers.
abstract: The purpose of this study was to test whether a long duration of aerobic high-intensity interval training is more effective than shorter intervals at a higher intensity in highly trained endurance athletes. The sample comprised of 12 male and 9 female, national-level, junior cross-country skiers (age, 17.5 ± 0.4 years, maximal oxygen uptake (V[Combining Dot Above]O2max): 67.4 ± 7.7 ml min kg), who performed 8-week baseline and 8-week intervention training periods on dry land. During the intervention period, a short-interval group (SIG, n = 7) added 2 weekly sessions with short duration intervals (2- to 4-minute bouts, total duration of 15-20 minutes), a long-interval group (LIG; n = 7) added 2 weekly sessions with long duration intervals (5- to 10-minute bouts, total duration of 40-45 minutes). The interval sessions were performed with the athletes' maximal sustainable intensity. A control group (CG; n = 7) added 2 weekly sessions with low-intensity endurance training at 65-74% of maximal heart rate. Before and after the intervention period, the skiers were tested for time-trial performance on 12-km roller-ski skating and 7-km hill run. V[Combining Dot Above]O2max and oxygen uptake at the ventilatory threshold (V[Combining Dot Above]O2VT) were measured during treadmill running. After the intervention training period, the LIG-improved 12-km roller ski, 7-km hill run, V[Combining Dot Above]O2max, and V[Combining Dot Above]O2VT by 6.8 ± 4.0%, 4.8 ± 2.6%, 3.7 ± 1.6%, and 5.8 ± 3.3%, respectively, from pre- to posttesting, and improved both performance tests and V[Combining Dot Above]O2VT when compared with the SIG and the CG (all p < 0.05). The SIG improved V[Combining Dot Above]O2max by 3.5 ± 3.2% from pre- to posttesting (p < 0.05), whereas the CG remained unchanged. As hypothesized, a long duration of aerobic high-intensity interval training improved endurance performance and oxygen uptake at the ventilatory threshold more than shorter intervals at a higher intensity.
authors.affiliation: Department of Human Movement Science, Norwegian University of Science and Technology, Trondheim, Norway. oyvind.sandbakk@svt.ntnu.no
authors.forename: Øyvind
authors.initials: Ø
authors.lastname: Sandbakk
authors.forename: Silvana B
authors.initials: SB
authors.lastname: Sandbakk
authors.forename: Gertjan
authors.initials: G
authors.lastname: Ettema
authors.forename: Boye
authors.initials: B
authors.lastname: Welde
mesh_terms: D000293:Adolescent; D054874:Athletic Performance; D005260:Female; D006801:Humans; D008297:Male; D009664:Norway; D010101:Oxygen Consumption / Q000502:physiology; D010806:Physical Education and Training / Q000379:methods*; D010807:Physical Endurance / Q000502:physiology*; D012420:Running / Q000502:physiology; D012865:Skiing / Q000502:physiology*; D013997:Time Factors