Purpose: To determine if the typical exacerbation of symptoms in patients with chronic fatigue syndrome (CFS) following a bout of exercise differs between high-intensity interval training (HIIT) or continuous (CONT) aerobic exercise of the same duration and mechanical work.
Methods: Participants with specialist-diagnosed CFS performed two 20-minute bouts of cycling in a randomised crossover study. The bouts were either moderate-intensity-continuous (70% age predicted heart rate max (APHRM)) or high-intensity-interval exercise, separated by at least 2 weeks. Self-report questionnaires capturing fatigue and related symptoms, and actigraphy were collected across 2 days before and 4 days following the exercise. Comparisons between exercise bouts were made using paired sample t-tests.
Results: Fourteen moderately affected participants who were unable to work, but not bed bound, completed the study (9 female, 32 +/- 10 years, 67 +/- 11 kg). Mechanical work was matched successfully between the exercise bouts (HIIT 83,037 vs CONT 83,348 J, p=0.84). Mean heart rate (HIIT 76 +/- 5 vs CONT 73 +/- 6 %APHRM, p<0.05) and RPE (6-20) in the legs (HIIT 15.4 +/- 1.4 vs CONT 13.2 +/- 1.2, p<0.001) were higher for the interval compared to continuous exercise. Mean fatigue scores (0-10) were similar before each exercise challenge (HIIT 4.5 +/- 1.8 vs CONT 4.1 +/- 1.7, p=0.43). Participants reported an increase in fatigue scores following both challenges (Mean difference: HIIT 1.0 +/- 1.3, p<0.01; CONT 1.5 +/- 0.7, p<0.001), but these exacerbations in fatigue were not statistically or clinically different (p=0.20).
Conclusions: High-intensity interval exercise did not exacerbate fatigue any more than continuous exercise of comparable workload. This finding supports evaluation of HIIT in graded exercise therapy interventions for patients with CFS.
Fatigue Exacerbation by Interval or Continuous Exercise in Chronic Fatigue Syndrome, by Carolina X Sandler, Andrew R Lloyd, Benjamin K Barry in Medicine & Science in Sports & Exercise, May 13, 2016 [Published Ahead-of-Print]