A systematic review of brief respiratory, embodiment, cognitive, and mindfulness interventions to reduce state anxiety

The study addresses the urgent need to identify effective single-session (acute) psychotherapeutic strategies to reduce state anxiety, given its high and rising prevalence and barriers to accessing multi-session therapies. Grounded in the role of interoception in emotion, the review examines whether brief cognitive (top-down), embodiment (body-focused), breathing (interoceptive/physiological), and combined (e.g., mindfulness/acceptance-based) interventions acutely reduce state anxiety. The core questions are which strategies are most effective in a single session and whether passive attention versus active change within each modality differentially impacts outcomes.

Background literature highlights: (1) traditional cognitive and relaxation therapies (e.g., cognitive restructuring, progressive muscle relaxation) reduce anxiety but some breathing instructions can exacerbate anxiety, particularly in panic disorder; (2) CBT typically shows large effects for anxiety and may improve interoceptive abilities, though it is unclear whether cognitive or embodiment components drive these effects; (3) embodiment practices, notably progressive muscle relaxation, show strong reductions in stress/anxiety/depression and may act via interoceptive pathways; (4) breathing techniques can reduce physiological and anxiety symptoms, but effects depend on the specific technique; (5) third-wave approaches (mindfulness/acceptance) that emphasize attention to thoughts and sensations (without active manipulation) reduce anxiety and can increase interoceptive sensitivity; (6) clinical guidelines emphasize multi-session therapies, but single-session approaches can reduce risk/symptoms and may promote continued self-practice. These lines of evidence motivate a focused assessment of acute effects by modality and by active change versus passive attention mechanisms.

Design and registration: Systematic review and meta-analysis conducted per PRISMA 2020; prospectively registered in PROSPERO (CRD42024507585). Search strategy: PubMed, PsycINFO (Ovid), and Scopus searched in October 2023 using: (Brief OR Acute OR Immediate) AND (Breath* OR Respir OR Relax* OR Progressive Muscle Relaxation) AND (Practice OR Intervention) AND (Anxiety OR Anxiety Sensitivity OR Anxiety Rating OR Anxiety Measure). English language, human participants. Reference lists of included articles were screened. Inclusion criteria: (1) adults >18 without medical diagnoses; (2) experimental trials of acute cognitive, respiratory, or embodiment techniques (or combinations); (3) included a state anxiety outcome; (4) randomized clinical trials. Longitudinal studies were considered if pre–post data for the first session were available. Study selection: From 2080 records, 353 duplicates removed; 1727 screened; 54 full texts sought (2 not retrieved); 52 assessed; plus 13 via citation searches. Exclusions included chronic interventions, no/inappropriate state anxiety measures, incorrect interventions/designs, stress tasks between pre–post, secondary analyses, or insufficient data. Twelve RCTs were included (3 cross-over). Risk of bias: Assessed using Cochrane RoB 2 (parallel and cross-over, including carryover/period effects for cross-over). Domains: randomization, deviations from intended interventions, missing outcome data, outcome measurement, selective reporting. Meta-analysis: Conducted in RevMan Web with random-effects model (inverse variance, 95% CI). Effect size: Hedges’ g computed from pre–post mean differences and SD of the difference (SDdiff) for intervention and control. Where SDdiff was not reported, it was estimated using SDdiff = sqrt(SDpre^2 + SDpost^2 − 2*r*SDpre*SDpost) with r = 0.7 (Cochrane recommendation). Heterogeneity assessed via chi-squared and I2 (25% low, 50% moderate, 75% high). Analyses were grouped by modality and strategy: (1) cognitive-based; (2) embodiment; (3) breathing-based (active change vs attention); (4) combined interventions (active change vs attention). Additional comparative analysis of breathing vs combined interventions provided in Supplementary material. Publication bias: Funnel plot and Egger’s test across all studies due to small numbers per subgroup. A significant outlier (Pawlow and Jones, 2005) induced asymmetry; a sensitivity analysis excluding this study was used in the embodiment meta-analysis.

Study sample: 12 randomized trials (3 cross-over). Risk of bias: 3 low overall risk, 8 some concerns, 1 high. Publication bias: Funnel plot asymmetry driven by an outlier (Pawlow and Jones, 2005); Egger’s test intercept = -9.28, t = 4.58, p < 0.001. Excluding the outlier reduced asymmetry (intercept = -5.24; t = 2.09; p = 0.06). Cognitive-based (active change to thoughts): One study of cognitive reappraisal (16.5 min) showed a significant moderate effect reducing state anxiety versus control: g = -0.69 (95% CI [-1.08, -0.31]); Z = 3.54; p = 0.0004. Embodiment (active body relaxation) versus control: Significant overall reduction: g = -1.05 (95% CI [-1.99, -0.11]); Z = 2.20; p = 0.03; high heterogeneity (I2 = 83%). Progressive muscle relaxation showed large effects (e.g., g = -1.57 [95% CI -2.22, -0.92]); deep relaxation training showed moderate effects. Breathing-based interventions versus control: Overall nonsignificant effect: total g = -0.29 (95% CI [-0.86, 0.28]); high heterogeneity (I2 = 88%). - Active change to breathing: g = -0.46 (95% CI [-2.18, 1.25]); Zeidan 2010 deep breathing (20 min) had a large significant effect g = -1.35 (95% CI [-1.96, -0.75]), whereas Telles 2019 alternate nostril breathing favored control (g = 0.40 [95% CI 0.00, 0.79]). - Attention to breathing: g = -0.21 (95% CI [-0.75, 0.34]); mixed, none significant as a subgroup; I2 = 80%. Combined interventions versus control: Significant overall reduction: g = -0.66 (95% CI [-1.07, -0.24]); Z = 3.07; p = 0.002; I2 = 69%. - Passive attention to combined modalities (e.g., mindfulness attention to breath/body/cognition): g = -0.91 (95% CI [-1.24, -0.59]); low heterogeneity (I2 = 12%); Z = 5.57; p < 0.00001. - Active changes to combined modalities (e.g., functional relaxation, relaxation changing breath/body): g = -0.24 (95% CI [-0.96, 0.49]); not significant; I2 = 73%. Overall pattern: Cognitive reappraisal (active) and embodiment (active) reduce state anxiety; breathing-only interventions show technique-dependent and inconsistent effects; combined mindfulness-style attention-based practices show consistent moderate benefits.

Findings indicate that brief, single-session interventions can reduce state anxiety, but efficacy varies by modality and strategy. Purposeful changes to body state (embodiment) and cognitive reappraisal reliably reduce state anxiety, supporting the role of both bottom-up interoceptive and top-down cognitive mechanisms. Breathing-only interventions demonstrate mixed results, highlighting the importance of technique selection (e.g., deep breathing effective; alternate nostril breathing not acutely effective and may be challenging for novices). Combined, mindfulness-like attention to breath/body/cognition yields consistent, moderate benefits with low heterogeneity, suggesting that passive attention across modalities may simultaneously engage interoceptive and cognitive pathways. High heterogeneity across many analyses, publication bias indications, and limited study numbers constrain firm generalizations. While interoceptive processes are plausible mediators, most studies did not measure interoception, so mechanistic conclusions remain preliminary.

Brief, single-session interventions targeting cognition (reappraisal), body relaxation (PMR, deep relaxation), and some forms of breathing can reduce state anxiety, with embodiment practices showing consistent benefits. Among combined approaches, passive attention-based mindfulness strategies (attention to breath/body/cognition) appear more consistently effective than active change strategies. Selecting appropriate breathing techniques is critical, as not all are acutely anxiolytic. Future research should expand high-quality RCTs, directly assess interoceptive changes as mediators, examine moderators such as delivery mode (facilitator-led vs audio), session duration, population characteristics (including sex), and compare active versus attention-focused strategies within each modality.

- Limited number of eligible randomized controlled trials for acute interventions, contributing to high heterogeneity and unstable pooled estimates. - Risk of bias concerns: incomplete reporting or nonstandard randomization methods in several studies; blinding challenges inherent to behavioral interventions. - Evidence of publication bias; results sensitive to an outlier study; limited ability to perform comprehensive bias corrections within RevMan. - SD of the pre–post difference (SDdiff) often unreported and estimated using an assumed correlation (r = 0.7), introducing uncertainty into effect sizes. - Variability in intervention delivery (facilitator-led vs audio), session duration (≈11.7–90 min), and populations (e.g., male soldier samples) not analyzed as moderators. - Lack of concurrent measurement of interoception limits mechanistic interpretation of interoceptive mediation. - Single available study for purely cognitive modality limits generalizability of that subgroup.