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Table 2 Summary of study designs, participants’ characteristics, and characteristics of the interventions of the reviewed studies

From: Effects of Intermittent Hypoxia–Hyperoxia on Performance- and Health-Related Outcomes in Humans: A Systematic Review

References

Design

Participants

Training characteristics

Characteristics of IHHE

 

(1) Study design

(2) Comparison groups

(1) Participants’ characteristics

(2) Number of participants (f/m)

(3) Mean age ± SD in years

(4) Mean height ± SD in cm/mean weight ± SD in kg/mean BMI ± SD in kg/m2

(1) Type and description of exercise

(2) Single session duration

(3) Training duration

(4) Training frequency

(5) Training density

(6) Training setting

(1) Intensity of hypoxia/hyperoxia (FiO2)

(2) Intra-session frequency (number of cycles)

(3) Intra-session density (Duration of a single hypoxic/hyperoxic period)

(4) Total time of IHHE procedure

(5) Participants’ mean SpO2 at IHHE (hypoxic condition)

(6) Intervention duration

(7) Inter-session frequency of IHHE sessions

(8) Inter-session density of IHHE sessions

(9) Number of total sessions across the intervention duration

Bayer et al. [106]

(1) Randomized controlled trial

(2) 2 groups

 [1] IHHE (normobaric IHHE and individual multimodal rehabilitation training)

 [2] Sham IHHE (simulated IHHE (normobaric normoxic air) and individual multimodal rehabilitation training)

(1) Geriatric patients

(2) IHHE: 18 (13/5)

Sham IHHE: 16 (14/2)

(3) IHHE: 80.9 ± 7.8

Sham IHHE: 83.4 ± 5.5

(4) IHHE: 163.7 ± 8.3/72.0 ± 9.3/27.0 ± 3.9

Sham IHHE: 163.2 ± 8.5/66.8 ± 12.3/25.0 ± 6.6

(1) Individual multimodal traininga

(2) N.R.

(3) 5–6 weeks

(4) 2–3 sessions/week (16–20 sessions)

(5) N.R.

(6) 30 min physiotherapy (balance training, coordination training, and exercises to stimulate energy metabolism), 60 min occupational therapy (motor functional training, perceptual training, mental training, and cognitive training), and 20 min cycling

(1) 0.12/0.35

(2) N.R.

(3) 4–6 min/1–2 min

(4) 35–45 min

(5) N.R.

(6) 5–6 weeks

(7) 2–3 sessions/week

(8) N.R.

(9) 14–15 sessions

Glazachev et al. [107 ]

(1) Controlled trial

(2) 2 groups

 [1] IHHE (normobaric IHHE)

 [2] Sham IHHE (patients were enrolled after completing a standard cardiac rehabilitation program (8 weeks, 2 days/week), simulated IHHE (normobaric normoxic air))

(1) Patients with coronary arterial disease (NYHA functional class II and III)

(2) IHHE: 27 (18/9)

Sham IHHE: 19 (10/9)

(3) IHHE: 63.9 ± 13.9

Sham IHHE: 79.1 ± 12.5

(4) IHHE: N.R./81.6 ± 13.9/N.R.

Sham IHHE: N.R./79.1 ± 12.5/N.R.

(1) N.A.

(2) N.A.

(3) N.A.

(4) N.A.

(5) N.A.

(6) N.A.

(1) 0.10–0.12/0.30–0.35

(2) 5–7 cycles

(3) 4–6 min/3 min

(4) N.R.

(5) N.R.

(6) 5 weeks

(7) 3 sessions/week

(8) N.R.

(9) 15 sessions

Susta et al. [108]

(1) Pilot study

(2) 2 groups

 [1] IHHE (normobaric IHHE and low-intensity running performed by athletes with overtraining syndrome)

 [2] Control group (healthy athletes performing training as usual)

(1) Young track and field athletes with and without overtraining syndrome

(2) IHHE: 15 (8/7)

CG: 19 (12/7)

(3) Overall: 18–20

(4) Overall: 176.4 ± 14.6/71.4 ± 6.9/N.R.

(1) 2 bouts of 30 min running at 40% VO2max with 10 min resta

(2) 70 min

(3) 4 weeks

(4) 3 days/week

(5) N.R.

(6) Low-intensity running

(1) 0.11/0.30

(2) 6–8 cycles

(3) 5–7 min/2–6 min

(4) 40–50 min

(5) N.R.

(6) 4 weeks

(7) 3 sessions/week

(8) N.R.

(9) 12 sessions

Dudnik et al. [109]

(1) Randomized controlled trial

(2) 2 groups

 [1] IHHE (normobaric IHHE)

 [2] Sham IHHE (simulated IHHE (normobaric normoxic air) and exercise program)

(1) Cardiology outpatients

(2) IHHE: 15 (N.R.)

Sham IHHE: 14 (N.R.)

(3) IHHE: 66.7 ± 5.7

Sham IHHE: 65.0 ± 6.2

(4) IHHE: N.R./N.R./27.7 ± 2.3

Sham IHHE: N.R./N.R./28.9 ± 2.0

(1) Standard tailored cardiopulmonary exercise program according to the European Society of Cardiologyb

(2) N.R.

(3) 8 weeks

(4) 150 min/week

(5) N.R.

(6) 12–13 at Borg scale and/or 64–75% of maximal heart rate

(1) 0.11–0.12/0.30–0.33

(2) 5–7 cycles

(3) 4–6 min/3 min

(4) N.R.

(5)

Glazachev et al. [110]

(1) Randomized controlled trial

(2) 2 groups

 [1] IHHE (normobaric IHHE)

 [2] Sham IHHE (simulated IHHE (normobaric normoxic air))

(1) Patients with chronic coronary artery disease and angina pectoris of functional class II–III

(2) Overall: 36 (26/10)

IHHE: 17 (N.R.)

Sham IHHE: 19 (N.R.)

(3) Overall: 68.2 ± 6.1

(4) N.R./N.R./N.R.

(1) N.A.

(2) N.A.

(3) N.A.

(4) N.A.

(5) N.A.

(6) N.A.

(1) 0.11–0.12/0.35

(2) N.R.

(3) 2–6 min/1–2 min

(4) 45–50 min

(5) N.R.

(6) 3 weeks

(7) 5 sessions/week

(8) 1 session per day for 5 days and 2 days rest (e.g. Monday to Friday: training, Saturday and Sunday: rest)

(9) 15 sessions

Serebrovska et al. [66]

(1) Randomized controlled trial

(2) 3 groups

 [1] IHHE (normobaric IHHE)

 [2] IHE (normobaric intermittent hypoxic exposure)

 [3] Sham IHHE (simulated IHHE (normobaric normoxic air))

(1) Patients with prediabetes

(2) IHHE: 17 (13/4)

IHE: 22 (15/7)

Sham IHHE: 16 (10/6)

(3) IHHE: 67.7 ± 7.7

IHE: 64.2 ± 6.6

Sham IHHE: 67.5 ± 8.7

(4) IHHE: 163 ± 6.0/84.9 ± 12.8/32.2 ± 4.6

IHE: 164 ± 9.5/86.3 ± 14.2/32.5 ± 6.7

Sham IHHE: 163 ± 6.0/84.9 ± 12.8/32.2 ± 4.6

(1) Intermittent hypoxic exposureb

(2) N.R.

(3) 3 weeks

(4) 5 sessions/week (15 sessions)

(5) N.R.

(6) Intermittent hypoxic exposure (5 min of hypoxia (12% FiO2) and 5 min of normoxia (~ 21% FiO2))

(1) 0.12/0.33

(2) 4 cycles

(3) 5 min/3 min

(4) N.R.

(5) N.R. (lowest: ~ 79%)

(6) 3 weeks

(7) 5 sessions/week

(8) N.R.

(9) 15 sessions

Serebrovska et al. [111]

(1) Pilot study

(2) 3 groups

 [1] IHHE (patients with mild cognitive impairments performing normobaric IHHE)

 [2] Sham IHHE (patients with mild cognitive impairments performing simulated IHHE (normobaric normoxic air))

 [3] Control group (healthy participants performing either IHHE nor Sham IHHE)

(1) Patients with mild cognitive impairments

(2) IHHE: 8 (6/7)

Sham IHHE: 6 (6/0)

Control group: 7 (6/1)

(3) IHHE: 68.2 ± 7.2

Sham IHHE: 72.6 ± 6.9

Control group: 63.0 ± 10.0

(4) IHHE: N.R./N.R./27.7 ± 2.0

Sham IHHE: N.R./N.R./26.3 ± 5.5

Control group: N.R./N.R./26.5 ± 3.6

(1) N.A.

(2) N.A.

(3) N.A.

(4) N.A.

(5) N.A.

(6) N.A.

(1) 0.12/0.33

(2) 4 cycles

(3) 5 min/3 min

(4) N.R.

(5) N.R.

(6) 3 weeks

(7) 5 sessions/week

(8) N.R.

(9) 15 sessions

Bestavashvili et al. [112]

(1) Randomized controlled trial

(2) 2 groups

 [1] IHHE (normobaric IHHE)

 [2] Sham IHHE (simulated IHHE (normobaric normoxic air))

(1) Patients with metabolic syndrome

(2) IHHE: 32 (18/14)

Sham IHHE 33 (14/19)

(3) IHHE: 60.0 (45.5; 65.5)

Sham IHHE: 61.5 (56.2; 66.0)

(4) IHHE: N.R./92.0 (81.0; 114.0)/34.3 (30.2; 38.0)

Sham IHHE: N.R./92.5 (82.8; 104.0)/32.4 (30.8; 35.8)

(1) N.A.

(2) N.A.

(3) N.A.

(4) N.A.

(5) N.A.

(6) N.A.

(1) 0.11–0.12/0.30–0.35

(2) N.R.

(3) 4–7 min/2–4 min

(4) 40–45 min

(5) N.R.

(6) 3 weeks

(7) 5 sessions/week

(8) One session per day for 5 days and 2 days rest (e.g. Monday to Friday: training, Saturday and Sunday: rest)

(9) 15 sessions

  1. BMI body mass index, CAD coronary artery disease, CG control group, f female, FiO2 fraction of inspired oxygen, IHE intermittent hypoxic exposure, IHHE intermittent hypoxia–hyperoxia exposure, m male, N.A. not available, N.R. not reported, NYHA New York Heart Association, RIP remote ischaemic preconditioning, SD standard deviation, SPO2 blood oxygen saturation measured with finger pulse oximeter
  2. aDescribes the characteristics of an additional training that is carried out in addition to the IHHE
  3. bDescribes the characteristics of the training that is performed by an control group