Case Report - High-intensity interval training in an adolescent with cystic fibrosis: A physiological perspective


H J Hulzebos, H Snieder, J van der Net, P J M Helders, and T Takken[1]


Nutritional, musculoskeletal, and/or ventilatory status can lead to a decreased exercise capacity in children
with cystic fibrosis (CF). Exercise training is already part of the usual care; however, the ‘‘optimal’’ intensity and
volume of exercise training to improve exercise capacity is still unknown. Six weeks of high-intensity interval
training (HIT) for a patient with CF with a ventilatory limitation was evaluated by a cardiopulmonary exercise
test (CPET). Peak oxygen uptake and peak workload increased 19% and 16%, respectively, and there was a
rise in peak ventilation from 50 L/min to 75 L/min, with an increase in both breathing depth and respiratory rate.
A relatively short period of HIT resulted in a significant increase in exercise capacity. In patients with CF, HIT
might be an effective and efficient training regimen, especially in CF patients with a ventilatory limitation.
Further research is necessary to investigate whether HIT is a better alternative than traditional aerobic training
programs especially in ventilatory limited patients with CF..

Patient Characteristics

  • Demographic Information: 16-year-old female
  • Medical diagnosis: Cystic Fibrosis. Diagnosed in her first year of age 
  • Related Medical Conditions: CF-related liver disease, Pseudomonas aeruginosa and Mycobacterium abscesses in her lungs and since 2005 an allergic bronchopulmonary aspergillosis (ABPA)
  • Previous care: Treated at the Children's Hospital, University Medical Clinic 
  • Treatment: Outpatient clinic visit. Patient complains of increased fatigue and SOB during field hockey.
    • She has lost a considerable amount of weight over a period of 3 months. Check up one month ago and her height and weight slightly below average.
    • Lung function has dropped significantly. FEV1 73% predicted dropped to a FEV1 of 49% predicted.
    • FEV1/FVC 83% predicted dropped to FEV1/FVC 63% predicted. Increased Residual Volume/ Total Lung Capacity of 51% predicted.
  • Medications: Ceftazidime and Tobramycine 3 weeks intravenously at home
  • Cardiopulmonary Exercise Test (CPET) was performed according to ATS- guidelines to evaluate her exercise performance


  • Subjective: Patient presents to outpatient clinic with complaints of increased fatigue and SOB during field hockey. She has lost a considerable amount of weight over a period of 3 months. She had a check up one month prior to outpatient visit and reported her height and weight to be slightly below average (height = 163.5cm, 22nd percentile; weight=49.3kg, 15th percentile. Lung function has also dropped significantly.
  • Medications: Ceftazidime and Tobramycine 3 weeks intravenously at home
  • Self Report Outcome Measures
  • Physical Performance Measure: Cardiopulmonary Exercise Test (CPET) was performed according to ATS- guidelines to evaluate her exercise performance.
  • Objective: Physical Examination Tests and Measures
    • FEV1 73% predicted dropped to a FEV1 of 49% predicted
    • FEV1/FVC 83% predicted dropped to FEV1/FVC 63% predicted
    • Increased Residual Volume/ Total Lung Capacity of 51% predicted

Clinical Impression

This patient presents with significantly decreased lung function and wants to return to playing a high-intensity sport. HIT training would be an effective intervention for this patient because it will result in improve aerobic and anaerobic capacity placing a maximal work load on her respiratory system.

Summarization of Examination Findings

  • Aerobic capacity more limited than total work capacity
  • Rapidly desaturated to <90% during exercise

"On the basis of the above findings, we considered her to be an appropriate candidate for HIT, because HIT might give her an additional training stimulus at the muscle level, without maximally taxing her ventilatory system during the interval training sessions."


  • The main goal was to increase her exercise capacity through HIT. This training regimen will put the least strain on her respiratory system, while still providing many of the physiological benefits of aerobic exercise in her locomotor muscles (Baquet et al, 2004). 
  • CPET was used to measure her exercise capacity pre and post intervention.
  • Phases of Interventions
  1. Steep ramp test on a bicycle ergometer to determine the "maximum short-time exercise capacity" (MSEC)
  2. Bicycle Ergometer Interval Training
  • Dosage and Parameters
  1. Steep ramp test for MSEC: After 3 minutes of unloaded pedaling, every 10 seconds the work rate was increased by 25 watts (W). The test was stopped at the moment that she could not maintain 60 revolutions per minute (rpm). This test was repeated every 2 weeks.
  2. Bicycle Ergometer Interval Training: 3x a week for 6 weeks. Each training session consisted of 10-20 intervals, alternating between 30 seconds of high intensity (50-90% MSEC) pedaling and a 60-second recovery period (25% MSEC). Pedaling rate was between 60 and 80 rpm. During each intervention, a Borg scale was used to evaluate her subjective feelings of fatigue and dyspnea.
  • Rationale for Progression
    • Based on the results of the steep ramp test, the optimal workload for training was determined.
    • To ensure that she was constantly challenged, the training program was progressively more demanding per week interval.
  • Co-interventions if applicable (e.g. injection therapy, medications): She was on prescription Ceftazidime and Tobramycine 3 weeks intravenously at home, because she was suspected of an infection leading to progression of her pulmonary symptoms. CPET was performed before and after IV treatment. Airway Clearance Techniques.


  • At the end of the 3-week intravenous treatment her weight had increased from 49.3 kg to 50.0 kg; no increase was found for height. Increase in pulmonary function for FEV1 was 13% and FEV1/FVC of 14%, RV/TLC decreased with 11%. Her CPET were symptom-limited as she stopped due to fatigued legs, which was represented by a score of 9 on the Borg scale (Borg, 1982).
  • On the first CPET her VO2peak was 1.54 L/min (70% of predicted), corrected for weight (VO2peak/kg) 31.3 mL/kg/min (80% of predicted). Peak workload was 163 watt (75% of predicted), corrected for weight (Wpeak/kg) 3.3 watt/kg (86% of predicted) with a ventilatory threshold (VT) of 54% of VO2peak predicted. Peak heart rate (HRpeak) was 171 beats per minute (89% of predicted), with a peak respiratory exchange ratio (RERpeak) of 1.18 (96% of predicted) (Table 2).
  • After the 3-week intravenous treatment, pulmonary function tests improved and exercise capacity showed little improvements in VO2peak (1 %), VO2peak/kg (1%), and Wpeak (2%), and watt/kg (0%).
  • During exercise she rapidly desaturated (after 6.30 minutes her SpO2 dropped , 90%), which is likely a primary factor of her low ventilatory reserve capacity (hypoventilation). 
  • After 6 weeks HIT program her lung functions further increased from an FEV1 of 62% of predicted to an FEV1 of 73% of predicted with a decreased of the RV/TLC of 35% of predicted. CPET showed improvements in VO2peak (0.43L/min; 18%), VO2peak/kg (7.0mL; 11%), and Wpeak (35watt; 16%), and watt/kg (0.6; 14%) (Table 2). There was also an indication for an increased oxygen delivery to the active muscle tissue; oxygen pulse (VO2peak/HFpeak) increased 10.3%. Oxygen extraction in these muscles, as indicated by the DVO2/DWR relationship, increased 4%, and there was an increase in the VT from 54% to 68% of VO2max predicted (Ross, 2003). She showed a rise in VEpeak from 64L/min to 75 L/min with an increase in both breathing depth, from a TV/VC of 44% to a TV/VC of 46%, and RR from 51 to 57 breaths per minute. There was no difference in ventilatory efficiency (VE/VO2 and VE/VCO2) and the ventilatory reserve capacity decreased from 23% to 214%.
  • During the last CPET her SpO2% decreased from 98% at rest to 90% at the end of the test after 11 minutes without saturation below 90%.
  • Finally, her participation into demanding physical activities (field hockey) increased over time from 10 minutes to 90 minutes.


HIT training intervals are considered to be an anaerobic exercise program, literature is showing however that HIT training has a positive carryover effect on the aerobic system. Anaerobic training could, therefore, be an important component of exercise programs for patients with CF. HIT training may be particularly important for those patients with CF who want to perform higher-intensity exercise, and study suggests may better mimic the physiological requirements of activities of daily living.



  1. 1.0 1.1 Hulzebos HJ, Snieder H, van der Net J, Helders PJM, Takken T. High-intensity interval training in an adolescent with cystic fibrosis: A physiological perspective. Physiotherapy Theory and Practice. 2011 Apr; 27(3): 231-237. 23 Mar 2014).