Table 4.

Outcomes.

Study	Cardio-respiratory system	Central nervous system	Time of physiological assessment	Psychological/Behavioral outcome
Critchley et al., 2015	HRV anticorrelated with BOLD signal in anterior insula, DLPFC, left occipital cortex	Increased BOLD activity in pons, thalamus, cerebellum, striatum, subparabrachial nucleus, parabrachial nuclei, locus coeruleus, periaqueductal gray, hypothalamus, hippocampus, motor, supplementary motor and parietal cortices	During slow breathing technique	A trend for increased alertness Non-significant comfort changes (ad-hoc scales)
Edmonds et al., 2009	Increased LF, SDNN, pNN50 Decreased HF, VLF	Not investigated	During slow breathing technique	Increased ease and comfort (ad-hoc scales)
Fumoto et al., 2004	Not investigated	Increased high-frequency alpha power	During and immediately after slow breathing technique	Increased vigor-activity (Profile of Mood States) Non-significant anxiety changes (State Trait Anxiety Inventory)
Gross et al., 2016	Increased HRV, SDNN, LF	Not investigated	During slow breathing technique	Increased somatic emotional regulation strategies (Somatic Strategies and Somatic Suppression scale)
Gruzelier et al., 2014	Increased SDNN	Not investigated	During slow breathing technique	Decreased anxiety (Depression, Anxiety, and Stress Scale)
Kharya et al., 2014	Non-significant change HRV, HF, LF/HF	Not investigated	After long-term slow breathing technique intervention (during rest)	Increased lifestyle management (Self “Well-Being” Inventory and Depression Screening Test)
Lehrer et al., 2003	Increased HRV, LF Decreased HF	Not investigated	During and immediately after slow breathing technique	Non-significant relaxation changes (Relaxation Inventory) Decreased side-effects of relaxation training (Side Effects of Relaxation Scale)
Lin et al., 2014	Increased LF, LF/HF, SDNN Non-significant change HF	Not investigated	During slow breathing technique	Increased relaxation Non-significant anxiety changes (ad-hoc scales)
Park and Park, 2012	Increased HF Decreased LF/HF Non-significant LF change	Increased alpha power Decreased theta power	During slow breathing technique	HF anticorrelated with cooperativeness and self-transcendence LF anticorrelated with self-transcendence Alpha power correlated with harm avoidance, novelty seeking, persistence, self-directedness, self-transcendence (Temperament and Character Inventory)
Sakakibara et al., 2013	Increased HF	Not investigated	Immediately after (during sleep in the following night)	Non-significant anxiety changes (State Trait Anxiety Inventory)
Siepmann et al., 2008	Non-significant change HRV	Not investigated	After long-term slow breathing technique intervention (during rest)	Non-significant mood changes (Beck Depression Inventory)
Stark et al., 2000	Increased HRV, LF, HF, LF/HF	Not investigated	During slow breathing technique	Non-significant emotional state changes (Self-Assessment Manikin Scale)
Tsuji, 2010	Not investigated	Non-significant change alpha power	During and immediately after slow breathing technique	Non-significant changes in mood (Two-Dimensional Mood Scale)
Van Diest et al., 2014	Increased LF Decreased HF Increased RSA	Not investigated	During slow breathing technique	Higher positive energy, higher pleasantness, and lower arousal
Yu et al., 2011	Not investigated	Increased alpha power Decreased theta power Increased oxygenated hemoglobin in anterior Prefrontal cortex	During and immediately after slow breathing technique	Decreased tension–anxiety, depression–dejection, anger–hostility, confusion (Profile of Mood States)