Short-term HIIT in deconditioned patients
ted bouts of effort varies and can last between 10 s and
several min, with varying recovery periods in between.
Previously, we designed a randomized clinical trial
(RCT) protocol with specific short-term pre-operative
HIIT for patients with stage IIIA NSCLC. In the
publication reporting the clinical results of this RCT
the HIIT training protocol was not presented in detail
(16). We therefore present here the proof-of-concept
of the specific HIIT protocol used in the earlier RCT
so that the method can be replicated. The feasibility
of short-term HIIT was tested in deconditioned pa-
tients with NSCLC in the pre-operative period and
the effects on aerobic capacity (VO 2peak ) and the 6-min
walk test (6MWT) were quantified. The time-window
for prehabilitation was from the time a decision was
made to perform surgery until the actual surgery. This
2–3-week period, used for preoperative examinations
and logistics, cannot be reduced in our setting and thus
provided an opportunity for prehabilitation.
The HIIT protocol was inspired by a study in cardiac
rehabilitation, reporting that HIIT at W peak was feasible
and safe in deconditioned patients with chronic heart
disease (17). Since many patients with NSCLC smoke
and experience dyspnoea on exertion, we expected that
this particular HIIT might limit the extent of dyspnoea
during training. Our hypotheses were that candidates
awaiting primary lung resection surgery for NSCLC
would be able to perform such HIIT despite decon-
ditioning, and that it would improve W peak , VO 2peak ,
resting heart rate (HR rest ), heart rate recovery (HR 1min ),
dyspnoea and exercise capacity in these patients.
METHODS
Design
The study was a registered PROBE trial using assessor
blinding and intention to treat analysis (ClinicalTrials.Gov:
NCT01258478 (16)). Following protocol approval by the
Geneva University Hospitals ethics committee (protocol 06-
225), informed written consent was obtained from patients
with suspected or proven NSCLC stage IIIA or less. Consenting
patients were randomized 1:1 into usual care (UC) or prehabi-
litation (PH)) using permuted blocks of 4. The randomization
sequence was generated before the trial began and was kept
concealed until the end of the study. Exclusion criteria were
contraindications to perform cardiopulmonary exercise testing
(CPET) (uncontrolled cardiac disease, severe pulmonary hyper-
tension, uncontrolled asthma) (18) and limitations to adhering
to the rehabilitation programme; for example, difficulty cycling.
713
Gas exchange was measured breath-by-breath with a metabolic
cart (Sensor Medics Model 2200 SP, Yorba Linda, CA, USA). In
these severely deconditioned patients the usual maximum criteria
could not be used and subjective exhaustion was the main reason
for cessation of the test. VO 2peak was determined as the highest
mean VO 2 over 20 s and W peak was defined as the highest power
maintained for 20 s (19). The ventilatory threshold (AT) was
determined with the V-slope method as primary criterion and
the first rise in the ventilatory equivalent for oxygen (VE/VO 2 )
as secondary criterion (20). CPET was repeated the day before
surgery. At enrolment the patients performed a 6MWT according
to ERS and ATS guidelines, repeated just prior to surgery (21).
High-intensity interval training
HIIT was performed between the decision for resection and
its realization. For logistic reasons this period lasts 2–3 weeks
in our setting. However, the waiting time for surgery was not
prolonged in order to accommodate prehabilitation. Experienced
respiratory physiotherapists supervised HIIT in personalized
sessions (1–3 patients at a time), 3 times a week. Patients
breathed room air throughout (no supplementary oxygen). HIIT
was performed on an upright electromagnetic cycle ergometer
(Motion Cycle 500, Emotion Fitness GmbH, Hochspeyer,
Germany). Seat height was adjusted, and foot buckles ensured
safety and comfort. The pedalling rate was 60–70 revolutions
per min (RPM). After a 5-min warm-up at 50% W peak , patients
performed HIIT, consisting of 15-s sprints at 100% W peak in-
terspersed by 15 s of passive resting periods, for 2 series of 10
min, with a 4-min rest period in between. This was followed by
a 5-min cool-down at 30% W peak (Fig. 1). The modified Borg
Scale (0–10) was used to quantify dyspnoea and leg fatigue.
During HIIT the patients were verbally encouraged. Ses-
sions lasted approximately 30 min, but could be terminated
prematurely upon strong dyspnoea, cardiac arrhythmia, or if the
patient did not feel well enough to complete the session. Initial
HIIT power output was set at 100%W peak , as measured during
the CPET after intake. If the patients were unable to complete
sessions at 100%W peak the power was lowered according to
their capacity to obtain a dyspnoea and leg fatigue of at least 5
Borg scale (i.e. less than “severe”). Power was increased again
if dyspnoea or the sense of effort decreased below 5. An upper
limit of 7 for dyspnoea and leg fatigue was set (corresponding
to “very severe”). Work rate was adjusted each session as Borg
Exercise testing
The primary study endpoint was pre- to post-prehabilitation
aerobic capacity change. After enrolment, patients performed
CPET according to ATS/ERS standards (American Thoracic
Society and European Respiratory Society) (18) on an upright
electronically braked ergometer (Ergoline GmbH, Germany).
Fig. 1. Overview of the high-intensity interval training (HIIT) paradigm.
After 5-min warm-up at 50% W peak the participants performed 2 × 10-min
blocks composed of 15-s sprints at 100% W peak interspersed by 15-s
pauses, and a 4-min pause between the 2 blocks. A cool-down period
of 5 min at 30% W peak completed the training.
J Rehabil Med 51, 2019