You may be familiar with IRT exercises, often just called isometrics by trainers and coaches, something like pushing against a wall or holding a plank pose. In more traditional strength training, like a squat or a push up, muscles shorten and lengthen during the movement, in IRT, muscles don’t change length.
IRT is not recommended by several international guidelines for the management of high blood pressure, mostly due to concerns over its safety because the static nature of IRT causes blood pressure to increase markedly during exercise, particularly when performed using large muscle groups or at high intensity, compared to traditional strength exercise or aerobic exercise.
However, this new research on the effectiveness of isometrics on managing high blood pressure, published August 12, 2021, in the Hypertension Research, the official journal of the Japanese Society of Hypertension, found isometric exercise to be safe and effective in meaningfully reducing blood pressure in people with high blood pressure.
The Curse of High Blood Pressure
High blood pressure affects 1.13 billion people around the globe and in 2019 it accounted for 10.8 million deaths. Worldwide, it’s the leading risk factor for mortality.
IRT is a very accessible and easy to perform intervention. It is good to know such a simple intervention could have such a strong effect on reducing blood pressure.
Title: The effectiveness and safety of isometric resistance training for adults with high blood pressure: a systematic review and meta-analysis
Date: August, 2021
Abstract: High blood pressure (BP) is a global health challenge. Isometric resistance training (IRT) has demonstrated antihypertensive effects, but safety data are not available, thereby limiting its recommendation for clinical use. We conducted a systematic review of randomized controlled trials comparing IRT to controls in adults with elevated BP (systolic ≥130 mmHg/diastolic ≥85 mmHg). This review provides an update to office BP estimations and is the first to investigate 24-h ambulatory BP, central BP, and safety. Data were analyzed using a random-effects meta-analysis. We assessed the risk of bias with the Cochrane risk of bias tool and the quality of evidence with GRADE. Twenty-four trials were included (n = 1143; age = 56 ± 9 years, 56% female). IRT resulted in clinically meaningful reductions in office systolic (–6.97 mmHg, 95% CI –8.77 to –5.18, p < 0.0001) and office diastolic BP (–3.86 mmHg, 95% CI –5.31 to –2.41, p < 0.0001). Novel findings included reductions in central systolic (–7.48 mmHg, 95% CI –14.89 to –0.07, p = 0.035), central diastolic (–3.75 mmHg, 95% CI –6.38 to –1.12, p = 0.005), and 24-h diastolic (–2.39 mmHg, 95% CI –4.28 to –0.40, p = 0.02) but not 24-h systolic BP (–2.77 mmHg, 95% CI –6.80 to 1.25, p = 0.18). These results are very low/low certainty with high heterogeneity. There was no significant increase in the risk of IRT, risk ratio (1.12, 95% CI 0.47 to 2.68, p = 0.8), or the risk difference (1.02, 95% CI 1.00 to 1.03, p = 0.13). This means that there is one adverse event per 38,444 bouts of IRT. IRT appears safe and may cause clinically relevant reductions in BP (office, central BP, and 24-h diastolic). High-quality trials are required to improve confidence in these findings.
Main Purpose: Identifying strategies to deal with global impact on health of high blood pressure. Exercise is one approach and this study focuses on the emergence of IRT as a mode of delivery.
Research Type: Journal Article
Findings Indicate: IRT is accessible and easy to perform providing benefits as a simple intervention for managing high blood pressure.
Limitation: The quality of research in this area is described as not being of high quality with some impact on confidence in the results.