PMID 38469374

Research
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Effects of constant-load exercise and high-intensity interval training on reliever medication consumption and peak expiratory flow in individuals with asthma: a randomised controlled trial

da Silva RA, Cukier A, Carvalho-Pinto RM, Carvalho CRF

Question

Does constant-load exercise or high-intensity interval training better reduce short-acting beta2-agonist use and improve peak expiratory flow during a 12-week exercise program in individuals with moderate-to-severe asthma?

Summary

Adults with clinically stable moderate-to-severe asthma were randomized to 12 weeks of supervised cycling constant-load exercise or cycling HIIT. Both programs reduced pre-exercise reliever medication use and improved aerobic fitness and asthma control. HIIT produced higher post-exercise peak expiratory flow responses and reached the minimal clinically important difference for ACQ-6 asthma control, but the authors cautioned that whether HIIT is preferable for people with greater airway hyperreactivity needs confirmation.

Methodology

  • Clinically stable adults aged 20-59 years with moderate-to-severe persistent asthma under medical treatment and pulmonologist monitoring.
  • 55 participants.
  • Cycle ergometer.
  • Work intervals: 30 seconds.
  • Recovery: 30 seconds active recovery at 40% Wmax.
  • Intensity: 80-140% CPET-derived Wmax by program phase.
  • 40 minutes planned: 5-minute warm-up, 30-minute exercise, 5-minute cool-down.
  • 2 sessions per week.
  • 12 weeks.
  • Randomized controlled trial; secondary analysis of a previous exercise trial focused on SABA consumption and PEF.
  • SABA consumption, Peak expiratory flow, Asthma clinical control, and Aerobic fitness were tracked.

Outcomes

SABA consumption

In week 1, 30% of CLE and 21% of HIIT participants required SABA; in the last week, 3.7% of CLE and none of HIIT required SABA. Total pre- and post-exercise SABA consumption decreased over the intervention in both groups, without between-group difference.

First versus last week reduction p<0.05; between-group difference p>0.05.

Improved

Peak expiratory flow

CLE had a small persistent post-exercise PEF reduction, whereas HIIT had PEF values above baseline; HIIT's total area under the curve was 2.8 times greater than CLE.

HIIT versus CLE p<0.05; all-session CLE PEF reduction p<0.05.

Improved

Asthma clinical control

Both groups improved asthma control, but only the HIIT group reached the ACQ-6 minimal clinically important difference.

ACQ-6 change CLE -0.23 +/- 1.06 versus HIIT -0.52 +/- 0.73; HIIT within-group p<0.05.

Improved

Aerobic fitness

Both groups improved aerobic fitness and reached the reported MCID for VO2peak; CLE had greater effect size for VO2peak, while HIIT had greater effect sizes for work rate, PEF, and ACQ-6.

VO2peak percent change reported in abstract as CLE 10.1 +/- 12.8% versus HIIT 5.7 +/- 15.6%; both reached >=1.0 mL/kg/min MCID.

Improved

Insights

  • A 30-second on/30-second off HIIT cycling protocol can be progressed over 12 weeks in clinically stable adults with moderate-to-severe asthma under supervision.
  • For asthma-sensitive programming, gradual progression and a short adaptation phase are important parts of the protocol, not incidental details.
  • HIIT may be more airway-friendly than continuous cycling for some asthma patients, but this should be framed as supervised clinical evidence rather than a general consumer guarantee.

Limitations

  • Secondary analysis; SABA and PEF sample-size calculation was difficult because prior studies had not assessed those outcomes after exercise training.
  • Small sample size and special clinical population.
  • Supervised cycle-ergometer setting with CPET-derived intensity limits direct translation to unsupervised bodyweight HIIT.
  • No long-term follow-up after intervention was reported.
  • Supplementary figures were referenced but not used as extraction sources.

Safety

  • No adverse events or injuries were explicitly reported in the paper.
  • PEF monitoring before and after sessions was used to guide SABA use.
  • Participants with PEF below 70% threshold were advised to use two 100 microg salbutamol doses.
  • Clinical exclusions limit translation to higher-risk asthma patients or those with cardiovascular/musculoskeletal disease.