Muscle & mechanical loading · graded by use, two uses
Inspiratory Muscle Training
Resting systolic blood pressure, high-resistance inspiratory muscle strength training.
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How this letter has changedLatest: October 2026 · Corrected.
Three trial results were written as differences against a control when the papers report changes within the training group: Ferreira et al. (PMID PubMed ID: the permanent number the US National Library of Medicine gives a published paper. Each one links to that paper's record on PubMed. 21985749), Ramos-Barrera et al. (PMID 32730174) and Ublosakka-Jones et al. (PMID 29604403), whose difference against its control was about 15 mmHg, not 20. The record also counted sleep apnea severity under its B; three pooled analyses found no improvement (Zuo et al., 2026; PMID 41721779; Chen et al., 2023; PMID 36576599; Silva de Sousa et al., 2024; PMID 37258418), so that use is graded D. Blood pressure holds B on a sham-controlled trial and two further pooled analyses (Li et al., 2023; PMID 37803506; Craighead et al., 2022; PMID 36107991).PMID 21985749 PMID 32730174 PMID 29604403 PMID 41721779 PMID 36576599 PMID 37258418 PMID 37803506 PMID 36107991
The replication The same finding reproduced by a separate research group. A result seen once can be chance or bias; a replicated one is harder to explain away. search of October found four further randomized trials in which inspiratory muscle training lowered blood pressure against sham A fake version of a procedure or device used as the comparison, so participants cannot tell which one they received. or control: Vranish et al. (Sleep, 2016; PMID 27091540) and Ramos-Barrera et al. (J Appl Physiol, 2020; PMID 32730174) in adults with sleep apnea, Ferreira et al. (Int J Cardiol, 2013; PMID 21985749) in hypertensive patients, and Ublosakka-Jones et al. (Exp Gerontol, 2018; PMID 29604403) in older adults with treated systolic hypertension. They repeat the direction and size of Craighead et al. (J Am Heart Assoc, 2021; PMID 34184544) in different populations. The written B asks for a trial supported by further trials, which this is; independence of groups is the A requirement, and blood pressure is a surrogate that caps the letter at B regardless. The flag comes off, and the record names the populations in which the finding has been repeated and the one in which it has not. Applied the written grade definition under the editor's standing instruction of October 2026 (Arnold Sandlow, D.C.).PMID 21985749 PMID 27091540 PMID 29604403 PMID 32730174 PMID 34184544
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Inspiratory muscle training means breathing in hard against a hand-held device that resists each breath. It works like weight training for the breathing muscles. In a trial of adults aged 50 to 79 with above-normal blood pressure, six weeks of hard training lowered the top number more than a fake, easy version. Pooled studies, some in people with sleep apnea, agreed. Blood pressure is a stand-in measure, not heart attacks or strokes. In sleep apnea, the training did not reduce the breathing pauses during sleep.
The B belongs to one of the two uses graded on this record. The other one carries its own letter.
As studied, and the trials
Craighead et al. (J Am Heart Assoc, 2021; PMID 34184544), double-blind Neither the participants nor the people assessing them know who received the real treatment until the trial ends. and sham-controlled, supported by Li et al. (J Clin Hypertens, 2023; PMID 37803506) and Craighead et al. (J Appl Physiol, 2022; PMID 36107991). Blood pressure is a surrogate, which caps the letter at B.
As studied, and the trials
Zuo et al. (Ann Am Thorac Soc, 2026; PMID 41721779), Chen et al. (Sleep Breath, 2023; PMID 36576599) and Silva de Sousa et al. (J Sleep Res, 2024; PMID 37258418) found no improvement in the apnea-hypopnea index. Tested and no benefit: D on Route 2 Human randomized trials have been run and did not show benefit on the stated outcome. One of the two routes to the lowest letter on EBL's scale..
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A letter describes the human evidence, not the product, the manufacturer, or the intervention's worth.
See the full evidence record →Graded on Resting systolic blood pressure.
Why this gradeThe reasoning, and what the grade does not cover.
Grade B on resting systolic blood pressure in midlife and older adults with above-normal pressure or sleep apnea. A sham-controlled trial (Craighead et al., 2021; PMID 34184544) is supported by pooled analyses (Li et al., 2023; PMID 37803506; Craighead et al., 2022; PMID 36107991; Chen et al., 2023; PMID 36576599; Zuo et al., 2026; PMID 41721779). The Arizona and Colorado groups share a funding grant, so their trials are collaborators rather than fully independent; the Brazilian and Thai trials are independent and small. Blood pressure is a surrogate, which caps the letter at B.
WHAT THIS GRADE DOES NOT COVERsleep apnea severity, where pooled trials found no benefit and the use is graded D; replacement of primary apnea treatment; clinical cardiovascular events; and adults with systolic pressure below 120.
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Each use, with its trials
This record carries a separate letter for each thing it has been measured on. The headline grade is the best of them, and it does not transfer to the others.
Craighead et al. (J Am Heart Assoc, 2021; PMID 34184544), double-blind and sham-controlled, supported by Li et al. (J Clin Hypertens, 2023; PMID 37803506) and Craighead et al. (J Appl Physiol, 2022; PMID 36107991). Blood pressure is a surrogate, which caps the letter at B.
Zuo et al. (Ann Am Thorac Soc, 2026; PMID 41721779), Chen et al. (Sleep Breath, 2023; PMID 36576599) and Silva de Sousa et al. (J Sleep Res, 2024; PMID 37258418) found no improvement in the apnea-hypopnea index. Tested and no benefit: D on Route 2.
The evidence, in fullTen papers, each linked to its PubMed record.
Craighead et al. (Journal of the American Heart Association, 2021; PMID 34184544): double-blind, sham-controlled trial, 36 completers aged 50 to 79 with systolic pressure at or above 120 mmHg, 30 breaths a day at about 75% of maximal inspiratory pressure for 6 weeks; casual systolic pressure fell from 135 to 126 mmHg with training and did not change with sham, and 24-hour systolic pressure was lower than sham. Li et al. (Journal of Clinical Hypertension, 2023; PMID 37803506): 12 articles, 386 participants, systolic -7.93 mmHg and diastolic -3.80 mmHg. Craighead et al. (Journal of Applied Physiology, 2022; PMID 36107991): five sham-controlled pilot trials pooled, systolic -9 mmHg with training and no change with sham. Chen et al. (Sleep and Breathing, 2023; PMID 36576599): 7 trials, 160 patients with sleep apnea, systolic -10.77 mmHg, low certainty, apnea-hypopnea index unchanged. Zuo et al. (Annals of the American Thoracic Society, 2026; PMID 41721779): 10 trials in sleep apnea, systolic -6.63 mmHg, no improvement in apnea-hypopnea index. Silva de Sousa et al. (Journal of Sleep Research, 2024; PMID 37258418): 13 trials at high risk of bias, training may not beat sham on the apnea-hypopnea index. Smaller trials: Vranish et al. (Sleep, 2016; PMID 27091540), single-blind, 24 adults with sleep apnea, systolic 12.3 mmHg lower than sham; Ramos-Barrera et al. (J Appl Physiol, 2020; PMID 32730174), 25 older adults with sleep apnea, systolic fell 8.8 mmHg within the training group while the low-resistance control did not change; Ferreira et al. (Int J Cardiol, 2013; PMID 21985749), 13 hypertensive patients, 24-hour systolic fell from 133.2 to 125.2 mmHg within the training group, no between-group comparison reported; Ublosakka-Jones et al. (Exp Gerontol, 2018; PMID 29604403), 32 older adults with treated systolic hypertension, home systolic fell 20 mmHg with slow loaded breathing against 5 mmHg with deep breathing.
Maximal inspiratory pressure (PImax) at baseline and every 4 weeks: this is the direct measure of the training effect. Resting systolic blood pressure at baseline and 6 weeks; Craighead et al. (PMID 34184544) reported a systolic reduction of about 9 mmHg with high-resistance inspiratory muscle strength training at 30 breaths/day over six weeks. Also monitor VO2max The most oxygen the body can use during all-out exercise, a standard measure of aerobic fitness. and submaximal exercise tolerance at 8 weeks.
Evidence notes: meta-analysis
Endpoint The outcome a trial measures to decide whether the treatment worked, such as heart attacks, blood pressure or a symptom score. graded: Resting systolic blood pressure (surrogate)
Last reviewed: October 2026
Educational use only · Not medical advice · EBL grades published human evidence and does not recommend treatment. Stopping a prescription is a decision for your physician.
Primary evidenceTen papers, each linked to its PubMed record.
Craighead et al. (Journal of the American Heart Association, 2021; PMID 34184544): double-blind, sham-controlled trial, 36 completers aged 50 to 79 with systolic pressure at or above 120 mmHg, 30 breaths a day at about 75% of maximal inspiratory pressure for 6 weeks; casual systolic pressure fell from 135 to 126 mmHg with training and did not change with sham, and 24-hour systolic pressure was lower than sham. Li et al. (Journal of Clinical Hypertension, 2023; PMID 37803506): 12 articles, 386 participants, systolic -7.93 mmHg and diastolic -3.80 mmHg. Craighead et al. (Journal of Applied Physiology, 2022; PMID 36107991): five sham-controlled pilot trials pooled, systolic -9 mmHg with training and no change with sham. Chen et al. (Sleep and Breathing, 2023; PMID 36576599): 7 trials, 160 patients with sleep apnea, systolic -10.77 mmHg, low certainty, apnea-hypopnea index unchanged. Zuo et al. (Annals of the American Thoracic Society, 2026; PMID 41721779): 10 trials in sleep apnea, systolic -6.63 mmHg, no improvement in apnea-hypopnea index. Silva de Sousa et al. (Journal of Sleep Research, 2024; PMID 37258418): 13 trials at high risk of bias, training may not beat sham on the apnea-hypopnea index. Smaller trials: Vranish et al. (Sleep, 2016; PMID 27091540), single-blind, 24 adults with sleep apnea, systolic 12.3 mmHg lower than sham; Ramos-Barrera et al. (J Appl Physiol, 2020; PMID 32730174), 25 older adults with sleep apnea, systolic fell 8.8 mmHg within the training group while the low-resistance control did not change; Ferreira et al. (Int J Cardiol, 2013; PMID 21985749), 13 hypertensive patients, 24-hour systolic fell from 133.2 to 125.2 mmHg within the training group, no between-group comparison reported; Ublosakka-Jones et al. (Exp Gerontol, 2018; PMID 29604403), 32 older adults with treated systolic hypertension, home systolic fell 20 mmHg with slow loaded breathing against 5 mmHg with deep breathing.
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Electronic inspiratory muscle strength training (IMST) device. The Craighead 2021 trial (PMID 34184544) used the POWERbreathe K3, an earlier model from the same maker, at 75% of maximal inspiratory pressure, 30 breaths a day, 6 days a week: in 36 adults aged 50 to 79, systolic pressure fell from 135 to 126 mm Hg over 6 weeks, and flow-mediated dilation improved about 45%, with no change on sham training.
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How EBL searched for the trials (1 search)
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("inspiratory muscle training"[tiab] OR "inspiratory muscle strength training"[tiab]) AND ("blood pressure"[tiab] OR hypertension[tiab] OR hypertensive[tiab]) AND (meta-analysis[pt] OR randomized controlled trial[pt])Grades move when new trials publish. A free monthly email lists every grade EBL moved, with the reason and the trial behind it: the sign-up is on the Evidence Log →