Table 3.

Virtual reality breathing studies: measures, training, and study duration.

Study	Measures	Training	Study duration
Abushakra et al [7], 2014	Physiological data: Lung size, lung capacity, and total lung capacity	No	Not applicable
Betka et al [49], 2022	Quantitative data: GAD-7a Physiological data: RRb, respiratory rate variability, HRc, and SpO2	No	VREd: 5 min; FESe: 16 min
Blum et al [25], 2019	Quantitative data: VASf, STAIg, Cognitive Interference Questionnaire, State Mindfulness Scale, relaxation self-efficacy, mind wandering, and respiration exercise experience Physiological data: HR	Yes	VRE: not reported; FES: 10 min
Blum et al [10], 2020	Quantitative data: User Experience Questionnaire Physiological data: HR and respiratory sinus arrhythmia	No	VRE: 7 min; FES: not reported
Brammer et al [41], 2021	Physiological data: RR	Yes	VRE: 15 min; FES: 15 min × 10 sessions, 3 weeks
Charoensook et al [31], 2019	Quantitative data: Self-perceived fitness level, gaming experience, and VRh experience Physiological data: HR and RR	No	VRE: 15 min; FES: 2 h
van Delden et al [5], 2020	Qualitative data: Questionnaire about what happened in the game, what was liked the most, and what was liked the least Quantitative data: VAS Physiological data: Lung function	No	VRE: not reported; FES: 30 min × 4 sessions
Feinberg et al [47], 2022	Qualitative data: Expert meditator interview and qualitative learning assessment (quality of experience) Quantitative data: Quantitative learning assessment	No	VRE: 5-15 min; FES: 10 sessions × 25 min
Gummidela et al [45], 2022	Quantitative data: Stroop Color and World Test Physiological data: RR	Yes	VRE: 5 min; FES: 20 min × 6 sessions
Heng et al [43], 2020	Quantitative data: Game experience Physiological data: Strong breathing, long breathing, and breathing strength control	No	VRE: not reported; FES: not reported
Hu et al [35], 2021	Quantitative data: Game experience Physiological data: Breathing strength	Yes	VRE: 6 min; FES: 23 min
Jung et al [27], 2020	Quantitative data: Patient Activation Measure, GAD-7, Patient Health Questionnaire-9, Short Physical Performance Battery, and Edmonton Frail Scale. Physiological data: HR and oxygen saturation	No	VRE: 20 min per day × 8 weeks; FES: 75 min
Kluge et al [36], 2021	Quantitative data: Nijmegen questionnaire Physiological data: RR	Yes	VRE: 9 min; FES: 90 min
Ladakis et al [37], 2021	Quantitative data: Self-reports and User Experience Questionnaire Physiological data: HR and electrodermal signal	No	VRE: 2.5 min; FES: 27 min
Mevlevioğlu et al [38], 2021	Quantitative data: Igroup Presence Questionnaire and visual height intolerance scale Physiological data: HR, brain electrical activity, electrodermal signal, and RR	No	VRE: 5 min; FES: not reported
Michela et al [44], 2022	Quantitative data: Dutch STAI, prior gaming experience, short self-constructed questionnaire before and after the intervention, and IMIi Physiological data: HRVj	Yes	VRE: 15 min; FES: 10 sessions × 15 min, 4 weeks
Patibanda et al [34], 2017	Qualitative data: Formal Analysis of Gameplay Physiological data: RR	Yes	VRE: 3 min; FES: not reported
Prpa et al [26], 2018	Qualitative data: Interviews Quantitative data: Music emotion recognition Physiological data: RR	Yes	VRE: 6 min; FES: 45 min
Quintero et al [32], 2019	Quantitative data: Customized questionnaire Physiological data: HRV	No	VRE: not reported; FES: 30 min
Rockstroh et al [39], 2021	Quantitative data: Breath awareness scale, PSS-10k, and Copenhagen Burnout Inventory Physiological data: RR, inhalation duration, and exhalation duration	Yes	VRE: 8 min; FES: 46 min
Rodrigues et al [50], 2022	Quantitative data: Edmonton Symptom Rating Scale, Borg Scale, HADSl, and Mini-Mental State Examination Physiological data: HR, RR, blood pressure, and SpO2	No	VRE: 10 min; FES: 40 min
van Rooij et al [40], 2016	Qualitative data: Qualitative observations of participants’ behavior Quantitative data: STAI, 7-point Likert scale on the experience of playing, self-reported positive and negative affect, and IMI Physiological data: diaphragm expansion and RR	No	VRE: 7 min; FES: not reported
Rutkowski et al [42], 2021	Quantitative data: Perception of Stress Questionnaire and HADS Physiological data: Lung function and expiratory volume	No	VRE: 20 minutes × 5 times, 2 weeks; FES: 30 min
Shih et al [24], 2019	Quantitative data: Self-reports based on 7-point Likert scales Physiological data: Acoustic signal of respiration, inhalation duration, exhalation duration, breathing cycles, and HRV	Yes	VRE: 6 min; FES: 50 min
Soyka et al [28], 2016	Quantitative data: PSS-10 Physiological data: RR, HR, HRV, and blood pressure	No	VRE: 10 min; FES: 25 min
Desnoyers-Stewart et al [33], 2019	Physiological data: RR	No	VRE: 5 min; FES: not reported
Tabor et al [8], 2020	Physiological data: RR, inhalation duration, and exhalation duration	No	VRE: not reported; FES: not reported
Tao et al [46], 2020	Quantitative data: Questionnaire for VR experience and Just Noticeable Difference Physiological data: Exhalation detection	Yes	VRE: 5 min; FES: not reported
Tatzgern et al [48], 2022	Quantitative data: Igroup presence questionnaire, Borg CR10 scale, Paas rating scale, Single Ease Question, and VR questionnaire Physiological data: Inhalation and exhalation	No	VRE: not reported; FES: 75 min
Tinga et al [29], 2018	Quantitative data: VAS for calmness Physiological data: RR, HR, HRV, and electroencephalography data	No	VRE: 6 min; FES: not reported
Tu et al [6], 2020	Quantitative data: Questionnaire for training effectiveness and user experience Physiological data: Breathing duration, movement of the chest, HR, and HRV	Yes	VRE: not reported; FES: 45 min
Zafar et al [30], 2018	Physiological data: RR	No	VRE: 6 min; FES: not reported

^aGAD-7: Generalized Anxiety Disorder-7.

^bRR: respiratory rate.

^cHR: heart rate.

^dVRE: virtual reality exposure.

^eFES: full experimental session.

^fVAS: visual analog scale.

^gSTAI: State-Trait Anxiety Inventory.

^hVR: virtual reality.

ⁱIMI: Intrinsic Motivation Inventory.

^jHRV: heart rate variability.

^kPSS-10: 10-item Perceived Stress Scale.

^lHADS: Hospital Anxiety and Depression Scale.