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C. Bhatia and B. Kayser
ratings and HR evolved, to target CPET-determined HR peak at
the end of sessions.
Measurements
Prior to HIIT, while quietly seated on a chair (5 min), resting
heart rate (HR rest ), resting dyspnoea (Dysp rest , Borg 0–10 scale),
and resting saturation (SpO 2rest ) were measured. During HIIT,
HR, SpO 2 , dyspnoea, and leg fatigue sensation (Borg 0–10 scale)
were monitored. The measurements were taken at the end of
warm-up, during HIIT (highest HR, HR session ) and 1 min after
the cool-down period (HR 1min ). SpO 2 and HR were measured
with a finger pulse-oximeter (Rad-5, Masimo Corporation,
Irvine, CA, USA).
High-intensity interval training sessions
There were no significant differences for any of the
measured variables between the first and the interme-
diate training sessions, except W session , which increased
(mean difference 11 watt, 95% CI 8–13 watt, p < 0.001)
and HR session , which increased (mean difference 8 bpm,
95% CI 6–11 bpm, p < 0.001) (see Fig. 2).
W session increased between the first and the last ses-
sion (mean difference 23 watt, 95% CI 20–26 watt,
p < 0.001). This was accompanied by a significant
increase in HR session (mean difference 14 bpm, 95% CI
Data analysis
For each patient, data for the first, middle and last HIIT train-
ing sessions were extracted and analysed. Data were analysed
using Stata (v. 12), R (v. 3.3.2) and Prism (v. 8). Results were
analysed using Student’s t-test, Mann–Whitney test and linear
mixed effect models with a random effect on subject and a fixed
effect on time for W peak , HR rest , HR session and HR 1min . Normality
of data distribution was checked visually. Data are presented
as means (with 95% confidence interval; 95% CI), medians
(with interquartile range; IQ25–75%) or means (with SD). The
alpha-level was set at 0.05.
RESULTS
Patients
A total of 189 patients were screened, 164 provided
consent and 13 were excluded. Data for a final total of
151 patients were available for analysis; 74 PH and 77
UC. The period from enrolment until surgery was simi-
lar in the 2 groups (PH: median 26 days, IQ25–75%,
21–33 days; UC: median 25 days, IQ25–75%, 20–40
days). Adherence to the prescribed training sessions for
PH was 87 ± 18% (median 8 sessions, IQ25–75%, 7–10
sessions). No adverse events were reported during the
training programme. Baseline characteristics of the
patients are shown in Table I. The 2 groups did not
differ for preoperative patient characteristics (see 16).
Table I. Baseline characteristics of the study population
Variables Usual care
(n = 77) Prehabilitation
(n = 74) p-value
Age, years, mean (SD)
BMI, kg/m 2 , n (%)
Sex, male, n (%)
FEV 1 predicted, % predicted
ppo FEV 1 , % predicted
D L CO, % predicted
ppoD L CO,% predicted
VO 2peak , ml/kg/min, mean (SD)
Distance 6MWT, m, mean (SD) 64 (10)
24.4 (4.1)
50 (65)
88 (19)
65 (14)
76 (19)
64 (17)
20.4 (5.7)
368 (143) 64 (13)
25.0 (4.5)
41 (55)
86 (22)
63 (17)
75 (21)
62 (19)
19.9 (5.7)
398 (167) 0.737
0.365
0.637
0.588
0.658
0.900
0.832
0.557
0.072
SD: standard deviation; BMI: body mass index; FEV 1 : predicted forced
expiratored volume in the first second; ppo FEV 1 : predicted post-operative
FEV 1 ; D L CO: lung diffusing capacity for carbon-monoxide; ppoD L CO: predicted
post-operative D L CO; VO 2peak : maximum oxygen uptake reached during cardio-
pulmonary exercise testing; 6MWT: distance covered walking in 6 minutes (m).
www.medicaljournals.se/jrm
Fig. 2. High-intensity interval training (HIIT) sessions 1–3. Resting
heart rate prior to the training (HR rest ,/min), power output during
training (W session , watt), heart rate reached during training (HR session ,/
min), 1-min recovery heart rate (HR1min,/min), dyspnoea (Borg 1–10)
and leg fatigue (Borg 1–10). Boxes represent the 25–75% percentiles,
whiskers represent the Tukey range, and lines in the box represent the
median values of the distribution.