Similar Inflammatory Responses following Sprint Interval Training Performed in Hypoxia and Normoxia.

Sprint interval training (SIT) is an efficient intervention capable of improving aerobic capacity and exercise performance. This experiment aimed to determine differences in training adaptations and the inflammatory responses following 2 weeks of SIT (30 s maximal work, 4 min recovery; 4-7 repetitions) performed in normoxia or hypoxia. Forty-two untrained participants [(mean +/- SD), age 21 +/- 1 years, body mass 72.1 +/- 11.4 kg, and height 173 +/- 10 cm] were equally and randomly assigned to one of three groups; control (CONT; no training, n = 14), normoxic (NORM; SIT in FiO(2): 0.21, n = 14), and normobaric hypoxic (HYP; SIT in FiO(2): 0.15, n = 14). Participants completed a (V) over dotO(2peak) test, a time to exhaustion (TTE) trial (power = 80% (V) over dotO(2peak)) and had hematological [hemoglobin (Hb), haematocrit (HO)] and inflammatory markers [interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF alpha)] measured in a resting state, pre and post SIT. (V) over dotO(2peak) (mL.kg(-1).min(-1)) improved in HYP (+11.9%) and NORM (+9.8%), but not CON (+0.9%). Similarly TTE improved in HYP (+32.2%) and NORM (+33.0%), but not CON (+3.4%) whilst the power at the anaerobic threshold (AT; W.kg(-1)) also improved in HYP (+13.3%) and NORM (+8.0%), but not CON (-0.3%). AT (mL.kg(-1).min(-1)) improved in HYP (+9.5%), but not NORM (+5%) or CON (-0.3%). No between group change occurred in 30s sprint performance or Hb and Hct. IL-6 increased in HYP (+17.4%) and NORM (+20.1%), but not CON (+1.2%), respectively. TNF-alpha increased in HYP (+10.8%) NORM (+12.9%) and CON (+3.4%). SIT in HYP and NORM increased (V) over dotO(2peak), power at AT and TTE performance in untrained individuals, improvements in AT occurred only when SIT was performed in HYP. Increases in IL-6 and TNF-alpha reflect a training induced inflammatory response to SIT; hypoxic conditions do not exacerbate this.