title: Eight weeks of intermittent hypoxic training improves submaximal physiological variables in highly trained runners.
abstract: It is unclear whether intermittent hypoxic training (IHT) results in improvements in physiological variables associated with endurance running. Twelve highly trained runners (VO2peak 70.0 ± 3.5 ml·kg-1·min-1) performed incremental treadmill tests to exhaustion in normobaric normoxia and hypoxia (16.0% FIO2) to assess submaximal and maximal physiological variables and the limit of tolerance (T-Lim). Participants then completed 8 weeks of moderate to heavy intensity normoxic training (control [CONT]) or IHT (twice weekly 40 minutes runs, in combination with habitual training), in a single blinded manner, before repeating the treadmill tests. Submaximal heart rate decreased significantly more after IHT (-5 ± 5 b·min-1; p = 0.001) than after CONT ( -1 ± 5 b·min-1; p = 0.021). Changes in submaximal V[Combining Dot Above]O2 were significantly different between groups (p ≤ 0.05); decreasing in the IHT group in hypoxia (-2.6 ± 1.7 ml·kg-1·min-1; p = 0.001) and increasing in the CONT group in normoxia (+1.1 ± 2.1 ml·kg-1·min-1; p = 0.012). There were no VO2peak changes within either group, and while T-Lim improved post-IHT in hypoxia (p = 0.031), there were no significant differences between groups. Intermittent hypoxic training resulted in a degree of enhanced cardiovascular fitness that was evident during submaximal, but not maximal intensity exercise. These results suggest that moderate to heavy intensity IHT provides a mean of improving the capacity for submaximal exercise and may be useful for pre-acclimatization for subsequent exercise in hypoxia, but additional research is required to establish its efficacy for athletic performance at sea level.
authors: 1College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom; 2British Swimming National Centre, Sports Training Village, University of Bath, Bath, United Kingdom; and 3Centre for Health, Applied Sport and Exercise Science, St. Mary's University College, Twickenham, United Kingdom.
authors: Ben A
authors: BA
authors: Holliss
authors: Richard J
authors: RJ
authors: Burden
authors: Andrew M
authors: AM
authors: Jones
authors: Charles R
authors: CR
authors: Pedlar
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology*; D000293:Adolescent; D005080:Exercise Test; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology*; D008297:Male; D010101:Oxygen Consumption; D064797:Physical Conditioning, Human / Q000379:methods* / Q000502:physiology*; D010807:Physical Endurance / Q000502:physiology*; D012420:Running / Q000502:physiology*; D016037:Single-Blind Method; D055815:Young Adult