PMID 41248139

Research
All papers

Box breathing or six breaths per minute: Which strategy improves athletes post-HIIT cardiovascular recovery?

Kasap M, Aydin GR

Question

Do box breathing, six breaths per minute, and spontaneous breathing differ in their acute effects on post-HIIT heart-rate recovery and perceived exertion?

Summary

In physically active sports science students, three post-HIIT breathing strategies were compared in randomized crossover order. Six breaths per minute looked less stressful than box breathing: box breathing produced higher final heart rate and higher perceived exertion, while recovery time to baseline heart rate did not differ significantly. The study was acute and limited to young active students.

Methodology

  • Forty Bartin University sports science students: 25 male and 15 female; age 20.95 +/- 1.75 years; BMI 22.97 +/- 3.25 kg/m2. Participants were athletes/physically active at least two days per week, familiar with cycle ergometer training, and had no known cardiopulmonary or orthopedic disorders or prior/current breathing/meditation practice.
  • 40 participants.
  • Spin-bike HIIT with recovery breathing protocols.
  • Work intervals: 30 sec.
  • Recovery: 60 sec guided breathing/rest.
  • Intensity: 85-95% estimated HRmax at constant 100 W resistance.
  • 15 min HIIT main exercise plus 10 min warm-up; recovery monitored until baseline HR returned.
  • Three acute sessions separated by at least 48 h.
  • Randomized crossover acute study
  • Initial heart rate after warm-up, Post-exercise/final heart rate immediately after final HIIT interval, Time to return to baseline heart rate, and Borg RPE after session were tracked.

Outcomes

Final heart rate

Final HR differed by breathing protocol: spontaneous 159.05 +/- 10.38 bpm, box breathing 164.65 +/- 9.40 bpm, 6 bpm 154.77 +/- 12.18 bpm; repeated-measures ANOVA p<.001.

p<.001

Mixed

Box breathing final heart rate

Box breathing had higher final HR than 6 bpm by +9.87 bpm (95% CI 6.32 to 13.42; p<.001).

95% CI 6

Improved

Heart-rate recovery time

Return time to baseline HR did not significantly differ: spontaneous 703.05 +/- 202.71 sec, box 753.02 +/- 150.60 sec, 6 bpm 675.70 +/- 157.24 sec; p=.128.

p=.128

No clear change

Perceived exertion

RPE differed by protocol: spontaneous 15.25 +/- 1.35, box 17.27 +/- 1.30, 6 bpm 15.25 +/- 1.08; p<.001.

p<.001

Mixed

Box breathing perceived exertion

Box breathing produced higher RPE than both 6 bpm and spontaneous breathing; both p<.001.

p<.001

Improved

Insights

  • Post-HIIT breath-hold box breathing may be counterproductive for immediate recovery comfort.
  • A simple 5-sec inhale/5-sec exhale rhythm is easier to translate into app cues and was less stressful than box breathing.
  • Do not promise faster HR recovery time from 6 bpm breathing because recovery time did not significantly differ.

Limitations

  • Acute single-application effects only; long-term adaptation unknown.
  • Young healthy physically active sports science students limit generalizability.
  • No HRV, end-tidal CO2, or respiratory-rate monitor outcomes.
  • Bike-based and guided setting may not generalize to unsupervised app use.

Safety

  • No adverse events were reported.
  • Box breathing increased physiological/perceptual stress compared with 6 bpm in this post-HIIT context.