PMID 29472870

Research
All papers

High-Intensity Interval Training in Normobaric Hypoxia Leads to Greater Body Fat Loss in Overweight/Obese Women than High-Intensity Interval Training in Normoxia

Camacho-Cardenosa A, Camacho-Cardenosa M, Burtscher M, Martínez-Guardado I, Timon R, Brazo-Sayavera J, Olcina G

Question

Does adding normobaric hypoxia to two types of cycling HIIT improve body-composition and substrate-oxidation outcomes in overweight or obese women?

Summary

This randomized double-blind study tested cycling HIIT in normoxia or simulated altitude in sedentary overweight/obese premenopausal women. Hypoxia plus HIIT produced greater fat-loss and muscle-mass signals than normoxia, but dropout was high and group-count reporting was inconsistent.

Methodology

  • Sedentary premenopausal overweight/obese women
  • 59 participants.
  • Cycle ergometer.
  • Work intervals: AIT 3 minutes; SIT 30 seconds.
  • Recovery: 3 minutes active recovery.
  • Intensity: AIT 90% Wmax; SIT 130% Wmax; recovery 55-65% Wmax.
  • AIT up to 41.5 minutes; SIT up to 29.62 minutes.
  • 3 sessions/week.
  • 12 weeks.
  • Randomized double-blind four-group intervention study
  • Fat mass, Muscle mass, Substrate oxidation, and Physiologic response were tracked.

Outcomes

Fat mass

Hypoxia groups lost more fat mass than normoxia counterparts.

SitH lower than SitN T1-T3 and T1-T4 p<0.05; AitH decreased vs AitN T1-T4 p<0.01.

Improved

Muscle mass

Muscle mass increased significantly in hypoxia groups.

AitH vs AitN T1-T4 p=0.022; SitH increased T1-T4 p<0.05.

Improved

Body fat percent

All groups decreased body fat percentage, with significant reductions in hypoxia groups.

Improved

Safety physiology

Hypoxia lowered oxygen saturation; HR and power were not significantly different.

SpO2 lower p<0.01.

Mixed

Insights

  • Hypoxia findings are not directly transferable to normal-air HIIT.
  • Progressive interval counts can be a useful programming structure.

Limitations

  • High dropout.
  • Diet and physical activity registered only twice.
  • No nonexercise control group.
  • Group count inconsistency.
  • Special equipment required.

Safety

  • No serious health problems were reported.
  • Twenty-three participants dropped out, reportedly due to health problems not related to the protocol, occupational factors, or personal problems.
  • Participants were screened for exercise contraindications and monitored with SpO2, HR, RPE, and supervision.
  • Group sample counts were inconsistent across article sections, creating uncertainty in exact final group sizes.