HIIT a safe and timesaving exercise option for adults with CF: Study
Patients showed higher adherence rates compared to conventional rehabilitation
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High-intensity interval training (HIIT), which alternates short periods of intense effort with equally short recovery periods, is safe and a feasible alternative to conventional training in adults with cystic fibrosis (CF), according to a small clinical trial in France.
The trial demonstrated that adults with CF who completed 10 minutes of HIIT cycling three times a week showed higher adherence rates and improvements in exercise capacity, muscle strength, lung function, and quality of life that were comparable to those seen with longer conventional rehabilitation.
The study, “Feasibility and tolerance of high-intensity interval training in adults with cystic fibrosis,” was published in Archives of Rehabilitation Research and Clinical Translation.
HIIT requires much less time for a complete workout
CF is caused by mutations in the gene encoding the CFTR protein, which acts as a gate that regulates the movement of chloride ions and water in and out of the cell.
The movement of chloride and water is essential for the production of mucus. When CFTR is abnormal, people produce thick, sticky mucus that accumulates and damages organs, including the lungs and pancreas. This results in symptoms such as shortness of breath and fatigue, and also increases the risk of diabetes.
It is recommended that people with CF regularly engage in physical activity to improve their physical capacity, lung function, and quality of life. Doctors usually recommend at least three 20-minute to 45-minute sessions per week, combining aerobic exercises that increase heart rate with resistance training to boost muscle strength. However, it can be difficult for people to stick to these exercise programs due to time constraints.
HIIT is a form of exercise that requires much less time for a complete workout. It incorporates several rounds that alternate short bursts of high-intensity movement to significantly increase heart rate to at least 80% of a person’s maximum heart rate, followed by short periods of lower-intensity movement or rest.
The breaks allow people to partially recover from shortness of breath and muscle fatigue, and small studies have shown that this form of exercise can benefit people with CF.
Patients randomly assigned to HIIT or conventional exercise
In this study, researchers aimed to compare HIIT with conventional exercise in CF patients and to determine which factors affected the feasibility and tolerability of a HIIT program.
Their clinical trial (NCT04888767) enrolled 62 adults at two centers in France. About one-third of participants had diabetes, and the majority (80.6%) were on CFTR modulators.
Patients were randomly assigned to HIIT or conventional exercise on a stationary exercise bicycle, performed over 18 days of inpatient rehabilitation under professional supervision. Each week, the HIIT group participated in three HIIT sessions and two low-intensity sessions, while the control group completed five 20- to 30-minute continuous work sessions.
The HIIT sessions began with a 2-minute warm-up, followed by six cycles of alternating 30 seconds of work and 30 seconds of rest, and ended with two minutes of recovery.
Overall, a significantly higher proportion of patients in the HIIT group complied with the exercise sessions than in the control group (93.3% vs. 86.7%). Lung function severity, CFTR modulator treatment, or diabetes did not affect compliance with HIIT, whereas those on conventional exercise who were taking CFTR modulators showed lower compliance.
Both exercise programs were generally well tolerated, with no serious adverse events reported. Most adverse events were deemed unrelated to the exercise programs, except for dizziness during exercise and low blood sugar in the HIIT group. Those on conventional exercise were more likely to have moderate side effects (83.3% vs. 50%).
This study demonstrated the feasibility and tolerance of a 3-week, inpatient HIIT programme in people with CF, with clinical benefits similar to conventional rehabilitation … and reaffirmed the effectiveness of physical training, including for people on CFTR modulator therapy.
In the HIIT group, patients not on modulator therapy had greater increases in shortness of breath and muscle fatigue and were more likely to experience side effects. Those with severe respiratory impairments also had greater increases in shortness of breath. These effects were not observed in controls.
This demonstrates “the feasibility of HIIT program for people with CF.” However “it does not appear to be suitable for those with severe respiratory impairment, and also those who are ineligible for modulator therapy,” the researchers wrote.
In terms of effectiveness, HIIT appeared to be as effective as conventional training for most participants. Both exercise programs increased exercise capacity and muscle strength (assessed in thigh muscles), though only the control group achieved the criteria for a minimum clinically important difference in muscle strength.
Lung function also increased in both groups, but the change was not considered clinically relevant. Both exercise programs increased patients’ quality of life and reduced anxiety scores, but only the control group showed benefits in depression.
“This study demonstrated the feasibility and tolerance of a 3-week, inpatient HIIT programme in people with CF, with clinical benefits similar to conventional rehabilitation … and reaffirmed the effectiveness of physical training, including for people on CFTR modulator therapy,” the researchers wrote. HIIT “could be used as a timesaving alternative to conventional treatment, particularly in people under CFTR modulator therapy.”
