Key result
Box breathing leads to ~10 bpm higher post-exercise heart rate than slow breathing after HIIT.
Why the study?
The acute effects of controlled breathing techniques, specifically box breathing versus 6 breaths per minute, following high-intensity interval training remained understudied.
Does controlled breathing (Box Breathing or 6 breaths per minute) improve post-exercise heart rate recovery and perceived exertion compared to spontaneous breathing in physically active students following HIIT?
RCT (n=40)
computer-generated random sequence
No
Does controlled breathing (Box Breathing or 6 breaths per minute) improve post-exercise heart rate recovery and perceived exertion compared to spontaneous breathing in physically active students following HIIT?
Standardized Mean Difference: 0.907 (95% CI 0.64–1.17)
Absolute Event Rate: 164.65% vs 154.77%
p-value: p=<0.001
Box breathing during recovery from high-intensity interval training paradoxically increases physiological and perceptual stress compared to 6 breaths per minute or spontaneous breathing in young athletes.
Box breathing may hinder post-HIIT recovery by raising heart rate and exertion; challenges its presumed benefits and extends acute breathing data in athletes.
Post-exercise recovery strategies are critical for athletic performance, yet the acute effects of controlled breathing techniques (box breathing vs. 6 bpm [6 breaths/min]) following high-intensity interval training (HIIT) remain understudied. This study compared three breathing protocols' impact on cardiovascular and perceptual recovery metrics. In a randomized crossover design, 40 physically active university students (25 males, 15 females; age 20.95 ± 1.75 years) completed three HIIT sessions on a spin bike (15 min, 1:2 work: rest ratio at 85-95% HRmax). One of three recovery breathing protocols was applied during each session: Spontaneous breathing (control), Box breathing (4-4-4-4), 6 bpm (5-5). Heart rate (HR) was monitored continuously, and perceived exertion was assessed via Borg Scale (6-20). Data were analyzed using repeated-measures ANOVA and Tukey's HSD post-hoc tests (α = 0.05). Box breathing elicited significantly: Higher post-exercise HR (164.65 ± 9.40 bpm) vs. 6 bpm (154.77 ± 12.18 bpm; p < 0.001*, Cohen's d = 0.907*) and spontaneous breathing (159.05 ± 10.38 bpm; p = 0.054*), Elevated perceived exertion (Borg 17.27 ± 1.30) vs. 6 bpm (15.25 ± 1.08; p < 0.001*) and spontaneous breathing (15.25 ± 1.35; p < 0.001*). No significant difference in recovery time was observed (p = 0.128*), though box breathing showed a trend toward delayed HR baseline recovery (753.02 ± 150.60 sec vs. 675.70 ± 157.24 sec with 6 bpm). While 6 bpm appears optimal for post-HIIT recovery, box breathing may impose physiological and perceptual stress. Practitioners should tailor breathing strategies to individual tolerance and exercise intensity. These findings highlight the need for personalized recovery protocols in athletic training.
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Kasap et al. (2025) conducted an RCT in Healthy active individuals (post-exercise recovery) (n=40). Box breathing (4-4-4-4) vs. 6 breaths per minute (6 bpm) and spontaneous breathing was evaluated on Post-Exercise Heart Rate (bpm) (Cohen's d 0.907, 95% CI 0.64 to 1.17, p=<0.001). Box breathing following high-intensity interval training elicited a significantly higher post-exercise heart rate compared to breathing at 6 breaths per minute (164.65 vs 154.77 bpm, p<0.001).
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