Isometric exercise training emerged as the most effective mode to reduce blood pressure in a systematic review and meta-analysis of 270 randomized trials with close to 16,000 participants.
The findings support the development of new exercise guidelines for blood pressure control, the authors say.
Previous research, based on older data that excluded high-intensity interval training (HIIT) and isometric exercise training (IET), led to aerobic exercise training (AET) being recommended for managing blood pressure, according to the authors.
Although AET, HIIT, dynamic resistance training (RT) and combined training (CT) are also effective in reducing both systolic (SBP) and diastolic blood pressure (DBP), the new analysis suggests that IET does it best.
The analysis showed reductions in blood pressure of 8.24/4 mm Hg after IET, compared with 4.49/2.53 mm Hg after AET; 4.55/3.04 mm Hg after RT; 6.04/2.54 mm Hg after CT; and 4.08/2.50 mm Hg after HIIT.
"These findings mirror our smaller-scale trials, and therefore we anticipated that isometrics would be largely effective," Jamie O'Driscoll, PhD, of Canterbury Christ Church University, Kent, UK told theheart.org | Medscape Cardiology. However, "the magnitude of difference between isometrics and some other modes was surprising."
The study was published online July 25 in the British Journal of Sports Medicine.
All Modes Effective
The investigators analyzed data from 270 randomized controlled trials including 15,827 people published between 1990 and February of this year. For consistency, the protocol/intensity of each included paper was screened against the Exercise Prescription in Everyday Practice and Rehabilitative Training tool to be defined and categorized.
All protocols were then stratified as AET, RT, CT, HIIT or IET.
As appropriate, protocols were then further stratified into subgroups: AET included walking, running, and cycling; HIIT included sprint interval training and aerobic interval training; and IET included isometric leg extension and isometric wall squat.
Healthy resting blood pressure was defined as a reading below 130/85 mm Hg, pre-hypertension as 130–139/85–89 mm Hg, and hypertension as 140/90 mm Hg or higher.
All exercise modes led to statistically significant reductions in SBP in normal blood pressure cohorts; however, all reductions were substantially larger in individuals with hypertension.
Pairwise analyses showed significant reductions in resting SBP and DBP following AET (−4.49/–2.53 mm Hg); RT (–4.55/–3.04 mm Hg), CT (–6.04/–2.54 mm Hg), HIT (–4.08/–2.50 mm Hg); and IET (–8.24/–4.00 mm Hg).
In the network meta-analysis, the rank order of effectiveness for SBP based on surface under the cumulative ranking curve (SUCRA) values were IET (SUCRA: 98.3%), CT (75.7%), RT (46.1%), AET (40.5%), and HIIT (39.4%).
Secondary network meta-analyses showed that isometric wall squat was the most effective submode for reducing SBP (90.4%), followed by isometric leg extension, isometric handgrip, cycling, running, CT, sprint interval training, other aerobic, RT, aerobic interval training, and walking.
Running was the most effective submode for lowering DBP (91.3%), followed by isometric wall squat, isometric handgrip, isometric leg extension, cycling, sprint interval training, RT, AIT, other aerobic, CT, and walking.
The authors acknowledge limitations, including variability in exercise interventions, missing data, variable quality of exercise monitoring and analyses, lack of blinding to group allocation, varying participant populations, and publication bias.
Nevertheless, they conclude, "The results of this analysis should inform future exercise guideline recommendations for the prevention and treatment of arterial hypertension."
"There are numerous organizations involved in providing and communicating population exercise guidelines," including WHO, American and European exercise guidelines, and NICE, O'Driscoll said. "We are currently developing an international collaborative project with other world leaders in the area to develop this line of enquiry."
In addition, the team is exploring the prescription of IET within England's National Health Service and extending the study to wider clinical populations.
Commenting on the study for theheart.org | Medscape Cardiology, John A. Osborne, MD, PhD, founder and director of State of the Heart Cardiology in Southlake, Texas, said, "This study further lends credence that other forms of exercise, beyond the usually recommended aerobic exercise promulgated in prior guidelines, have significant value for blood pressure lowering, and, potentially, may offer even greater benefits for…controlling hypertension."
"This study should inform contemporary nonpharmacological approaches to blood pressure management and allows providers more flexibility in different strategies of exercise to combat high blood pressure," said Osborne, a volunteer spokesperson for the American Heart Association.
That said, he added, "While this study by itself is extremely provocative, thoughtful, and rigorously performed, it should be used as hypothesis-generating and hopefully [will be followed by] head-to-head studies of aerobic exercise vs resistance training to confirm the findings."
The study received no funding. O'Driscoll and Osborne report no relevant financial relationships.
Br J Sports Med. Published online July 25, 2023. Abstract
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Cite this: Isometric Exercise Optimal for Lowering Blood Pressure? - Medscape - Aug 09, 2023.