AUTHOR=Richardson Alan J. , Relf Rebecca L. , Saunders Arron , Gibson Oliver R. 

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

JOURNAL=Frontiers in Physiology

VOLUME=7

YEAR=2016

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2016.00332

DOI=10.3389/fphys.2016.00332

ISSN=1664-042X

ABSTRACT=<p>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 ± <italic>SD</italic>), 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, <italic>n</italic> = 14), normoxic (NORM; SIT in FiO<sub>2</sub>: 0.21, <italic>n</italic> = 14), and normobaric hypoxic (HYP; SIT in FiO<sub>2</sub>: 0.15, <italic>n</italic> = 14). Participants completed a <inline-formula><mml:math id="M1" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover accent="true"><mml:mtext>V</mml:mtext><mml:mo>˙</mml:mo></mml:mover><mml:msub><mml:mtext>O</mml:mtext><mml:mrow><mml:mn>2</mml:mn><mml:mtext>peak</mml:mtext></mml:mrow></mml:msub></mml:mrow></mml:math></inline-formula> test, a time to exhaustion (TTE) trial (power = 80% <inline-formula><mml:math id="M2" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover accent="true"><mml:mtext>V</mml:mtext><mml:mo>˙</mml:mo></mml:mover><mml:msub><mml:mtext>O</mml:mtext><mml:mrow><mml:mn>2</mml:mn><mml:mtext>peak</mml:mtext></mml:mrow></mml:msub></mml:mrow></mml:math></inline-formula>) and had hematological [hemoglobin (Hb), haematocrit (Hct)] and inflammatory markers [interleukin-6 (IL-6), tumor necrosis factor-α (TNFα)] measured in a resting state, pre and post SIT. <inline-formula><mml:math id="M3" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover accent="true"><mml:mtext>V</mml:mtext><mml:mo>˙</mml:mo></mml:mover><mml:msub><mml:mtext>O</mml:mtext><mml:mrow><mml:mn>2</mml:mn><mml:mtext>peak</mml:mtext></mml:mrow></mml:msub></mml:mrow></mml:math></inline-formula> (mL.kg<sup>−1</sup>.min<sup>−1</sup>) 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<sup>−1</sup>) also improved in HYP (+13.3%) and NORM (+8.0%), but not CON (–0.3%). AT (mL.kg<sup>−1</sup>.min<sup>−1</sup>) improved in HYP (+9.5%), but not NORM (+5%) or CON (–0.3%). No between group change occurred in 30 s sprint performance or Hb and Hct. IL-6 increased in HYP (+17.4%) and NORM (+20.1%), but not CON (+1.2%), respectively. TNF-α increased in HYP (+10.8%) NORM (+12.9%) and CON (+3.4%). SIT in HYP and NORM increased <inline-formula><mml:math id="M4" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover accent="true"><mml:mtext>V</mml:mtext><mml:mo>˙</mml:mo></mml:mover><mml:msub><mml:mtext>O</mml:mtext><mml:mrow><mml:mn>2</mml:mn><mml:mtext>peak</mml:mtext></mml:mrow></mml:msub></mml:mrow></mml:math></inline-formula>, 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 TNFα reflect a training induced inflammatory response to SIT; hypoxic conditions do not exacerbate this.</p>