Table 2.

Virtual reality breathing studies: sample, study design, objective, and intervention.

Study	Sample	Study design	Objective	Intervention
Abushakra et al [7], 2014	125 males and females; age not reported	N/Aa	Develop breathing therapy	Normal breathing with visual feedback
Betka et al [49], 2022	19 males and 7 females; age: 18-55 years	CSb (mixed study), randomized, single-blind cross over	Investigate the effect of VRc on COVID-19 patients’ rehabilitation	Normal breathing with audiovisual feedback
Blum et al [25], 2019	29 males and 31 females; average age: 33.5 years	CS (VR, non-VR)	Investigate the effect of VR and slow-paced breathing on HRVd	Slow breathing with visual feedback
Blum et al [10], 2020	16 males and 56 females; age: 18-49 years	CS	Develop VR biofeedback system–based respiratory treatment	Slow diaphragmatic breathing with visual feedback
Brammer et al [41], 2021	9 males and females; age not reported	PSe	Develop VR biofeedback scenarios for stress-exposure training	Slow breathing with visual feedback
Charoensook et al [31], 2019	21 males and females; age: 20-24 years	CS (VR, non-VR)	Investigate how VR systems affect HRf and RRg	Normal breathing with visual feedback
van Delden et al [5], 2020	8 males and 4 females; age: 6-8 years	PS	Develop VR systems based on spirometry for children with asthma	Spirometry test with visual feedback
Feinberg et al [47], 2022	21 males and females; age: 18-34 years	Mixed methods	Design a VR system for meditation	Normal, slow, and diaphragmatic breathing with visual feedback
Gummidela et al [45], 2022	16 males and 14 females; age: 18-35 years	CS (game, nongame)	Develop a VR system for breathing training	Deep breathing with visual feedback
Heng et al [43], 2020	9 participants; gender and age not reported	PS	Integrate a breathing sensor with a VR system for pulmonary rehabilitation	Several breathing techniques with visual feedback
Hu et al [35], 2021	3 males and 3 females; age: 5-8 years	PS	Examine the effectiveness of combining breathing exercises with music rhythm through VR	Several breathing techniques with visual feedback and musical guidance
Jung et al [27], 2020	6 males and 4 females; age: 63-75 years	PS	Pulmonary rehabilitation among participants with COPDh	Educational videos and physical exercises with audiovisual feedback
Kluge et al [36], 2021	13 males and 17 females; age: 22-39 years	PS	Develop a VR system for stress management training	Several breathing techniques with visual feedback
Ladakis et al [37], 2021	2 males and 2 females; age: 23-59 years	CS (VR, non-VR)	Examine stress reduction in work environments through VR	Deep breathing exercises with visual feedback
Mevlevioğlu et al [38], 2021	7 males and 4 females; age: 18-30 years	PS	Develop a VR system for height exposure therapy (acrophobia)	Natural breathing with visual respiratory feedback
Michela et al [44], 2022	9 males; age: 26-55 years	PS	Develop a VR system for police officers’ breathing performance	Deep and slow diaphragmatic breathing with visual feedback
Patibanda et al [34], 2017	16 males and 16 females; age not reported	PS	Develop a VR system for PLBi training	PLB with visual feedback
Prpa et al [26], 2018	4 males and 7 females; age: 24-44 years	PS	Investigate breathing patterns according to VR to enhance breath awareness	Slow breathing with visual feedback
Quintero et al [32], 2019	5 males and 6 females; age: 23-32 years	PS	Develop a VR application for HRV analysis	Normal and slow breathing with visual feedback
Rockstroh et al [39], 2021	16 males and 29 females; age: 19-52 years	DDj	Develop a mobile VR-based respiratory biofeedback system	Diaphragmatic breathing with visual feedback
Rodrigues et al [50], 2022	22 males and 22 females; age: 18-80 years	CS	Investigate a VR system for the sensation of dyspnea in COVID-19 patients	Not reported
van Rooij et al [40], 2016	52 males and 34 females; age: 8-12 years	PS	Develop a VR breathing system for anxiety in children	Diaphragmatic breathing with visual feedback
Rutkowski et al [42], 2021	9 males and 41 females; age: 45-85 years	CS (VR, non-VR)	Examine the effectiveness of VR for depression and anxiety in participants with COPD	Pulmonary rehabilitation exercises with visual feedback
Shih et al [24], 2019	12 males and 31 females; average age: 25.9 years	PS	Develop a mobile app for detecting breathing phases	Normal and slow-paced breathing
Soyka et al [28], 2016	11 males and 10 females; age: 20-45 years	CS	Develop a VR application for stress management	Paced breathing techniques with visual feedback
Desnoyers-Stewart et al [33], 2019	Not reported	DD	Develop a VR application for breathing synchronization between participants	Paced breathing with visual feedback
Tabor et al [8], 2020	N/A	DD	Develop a VR breathing exercise system to support pneumonia rehabilitation	Positive expiratory pressure with visual feedback
Tao et al [46], 2020	3 participants; gender and age not reported	PS	Examine the latent breath input for music instrument performance in VR	Normal breathing with visual and audio feedback
Tatzgern et al [48], 2022	10 males and 2 females; age not reported	DD	Develop a VR system for resistance breathing training	Several breathing techniques with visual feedback
Tinga et al [29], 2018	23 males and 37 females; age: 18-31 years	CS	Examine the effectiveness of respiratory biofeedback through VR meditation	Audio-guided meditation through visual feedback
Tu et al [6], 2020	10 males and females; age not reported	PS	Develop a VR system for breathing training at home	RSAk with visual feedback
Zafar et al [30], 2018	100 males; average age: 23 years	CS	Develop a VR system for breathing training	Paced breathing with visual feedback

^aN/A: not applicable.

^bCS: control study.

^cVR: virtual reality.

^dHVR: heart rate variability.

^ePS: pilot study.

^fHR: heart rate.

^gRR: respiratory rate.

^hCOPD: chronic obstructive pulmonary disease.

ⁱPLB: pursed-lip breathing.

^jDD: design and development study.

^kRSA: respiratory sinus arrhythmia.