Which is the most effective form of exercise to reduce hypertension?

Hypertension is a major cause of premature death. The World Health Organisation¹ estimates that hypertension affects 1.28 billion people aged between 30 and 79. Furthermore, with an absence of symptoms, hypertension is a silent killer, leading to approximately 7.5 million global deaths.²

Drug treatment is the mainstay of management with a recent meta-analysis³ finding that reducing systolic blood pressure (SBP) by only 5 mmHg, lowered the risk of major cardiovascular events by 10%. But adherence to anti-hypertensive treatment is sub-optimal, with one analysis of over 13,500 patients,⁴ finding that 45.2% of patients were non-adherent to their hypertensive therapy.

In addition to pharmacotherapy, one recommended and effective lifestyle intervention is physical activity, i.e., exercise. In fact, a systematic review from 2012⁵ that included nearly 100,000 individuals, concluded that among those with hypertension who participated in any level of physical activity, their risk of all-cause and cardiovascular mortality was inversely related to physical activity.

For instance, those who engaged in any form of physical activity, saw a reduction in cardiovascular mortality of between 16 and 67%. However, the study did not consider factors such as the duration, frequency or intensity of physical activity. Nevertheless, with such large potential benefits, current guidelines⁶ include a recommendation for exercise and the general advice is that hypertensive patients should participate in at least 30 minutes of moderate-intensity aerobic exercises such as walking, jogging on at least five to seven days per week as well as strength training exercises (e.g., lifting weights) on two to three days a week.

High intensity interval training and hypertension

But more recently, there has been a good of interest in two other exercise modalities for their potential anti-hypertensive effect: high intensity interval training (Hiit) and isometric training. Hiit involves undertaking short bursts of “all out” exercise, such as sprinting or maximal effort cycling on a stationary bike. In contrast, isometric exercise involves the contraction of muscles, but without changes in length. In other words, holding a particular position without moving.

Both forms of exercise have been shown to produce an anti-hypertensive effect. For instance, a recent systematic review and meta-analysis⁷ that included 38 studies (18 for isometric training) with 1,583 participants, isometric training produced a larger reduction in systolic blood pressure (SBP) than Hiit (mean reductions of 8.5 vs 2.86 mmHg). There was also a greater decrease in diastolic blood pressure, DBP (4.07 vs 2.48 mmHg) but interestingly, Hiit training led to a superior reduction in resting heart rate (3.17 bpm vs 1.34 bpm).

But how do these newer modalities compare to aerobic and strength training and should either be incorporated into national guidelines? A recent review set out to answer this important question.

Hypertension lowering effect of different forms of exercise

In a review published in the British Journal of Sports Medicine,⁸ researchers set out to determine the optimal antihypertensive exercise regime by comparing different types. They included aerobic training, resistance exercise (i.e., strength training), a combination of aerobic and resistance exercise (i.e., the current recommendation), Hiit training and finally isometric exercises. They focused their attention only on randomised, controlled trials and looked at how each form of exercise affected both SBP and DBP blood pressures. The analysis included a total of 270 trials with nearly 16,000 participants and a summary of the results are given in the table.

Each of the observed reductions in both SBP and DBP were statistically significant compared with control groups. What is clear from the table, is how each of the different interventions is more effective than doing nothing, i.e., there are anti-hypertensive advantages from all types of exercise. But what is most striking is how isometric training provides the greatest blood pressure lowering benefit and which is nearly double to that from aerobic training. Finally, when the researchers looked at the data based on individual’s blood pressure status (i.e., normotensive, pre-hypertensive or hypertensive), each intervention was most effective in those who were hypertensive.

Comparative reductions in blood pressure from different exercise modalities

To put these findings into context, monotherapy with an antihypertensive,⁹ reduces SBP by an average of 10 to 15 mmHg and DBP by 8 to 10 mmHg. Thus, isometric exercise provides an additional reduction in blood pressure compared to the current recommendation for a combination of aerobic and strength training.

Which isometric exercise?

But what exactly is isometric training and what is involved? A common type of isometric training is holding a plank position. However, most of the clinical trials of isometric training used one of three exercises. First, wall squats, i.e., sitting against a wall, typically for 2-minutes, which was repeated up to four times per session and performed three times per week. Second, squeezing a handgrip device at 30% of the maximum grip strength for 2 minutes, up to three times per session.

Both walk squats and the use of a hand dynamometer device (see Figure 1) can easily be performed at home. The third type, isometric leg extensions that require the use of gym equipment.

Advice to patients

The most important take-home message is that while any form of exercise is a beneficial lifestyle intervention to lower blood pressure, isometric exercise provides the greatest reduction in blood pressure. So, when faced with a patient who eschews the gym or has little time to go for a walk, reassure them that they have options. It might seem bizarre asking them to sit against a wall for two minutes a couple of times a week or to squeeze a hand dynamometer, but the strategy does work and they won’t even need to leave the house.

Rod Tucker is a Pharmacist and independent researcher

References

1. World Health organisation. Available online at: https://www.who.int/news-room/fact-sheets/detail/hypertension [Accessed May 2024]
2. Blood pressure/hypertension. World Health Organisation. Available online at https://www.who.int/data/gho/indicator-metadata-registry/imr-details/3155 [Accessed May 2024]
3. Blood Pressure Lowering Treatment Trialists’ Collaboration. Pharmacological blood pressure lowering for primary and secondary prevention of cardiovascular disease across different levels of blood pressure: an individual participant-level data meta-analysis. Lancet. 2021 May 1;397(10285):1625-1636.
4. Abegaz TM, Shehab A, Gebreyohannes EA et al. Nonadherence to antihypertensive drugs: A systematic review and meta-analysis. Medicine (Baltimore). 2017 Jan;96(4): e5641. doi: 10.1097/MD.0000000000005641.
5. Rossi A, Dikareva A, Bacon SL et al. The impact of physical activity on mortality in patients with high blood pressure: a systematic review. J Hypertens. 2012 Jul;30(7):1277-88. doi: 10.1097/HJH.0b013e3283544669.
6. Williams B, Mancia G, Spiering W et al. ESC Scientific Document Group. 2018 ESC/ESH Guidelines for the management of arterial hypertension. Eur Heart J. 2018 Sep 1;39(33):3021-3104. doi: 10.1093/eurheartj/ehy339.
7. Edwards J, De Caux A, Donaldson J et al. Isometric exercise versus high-intensity interval training for the management of blood pressure: a systematic review and meta-analysis. Br J Sports Med. 2022 May;56(9):506-514. doi: 10.1136/bjsports-2021-104642.
8. Edwards JJ, Deenmamode AHP, Griffiths M et al. Exercise training and resting blood pressure: a large-scale pairwise and network meta-analysis of randomised controlled trials. Br J Sports Med. 2023 Oct;57(20):1317-1326. doi: 10.1136/bjsports-2022-106503.
9. Paz MA, de-La-Sierra A, Sáez M et al. Treatment efficacy of anti-hypertensive drugs in monotherapy or combination: ATOM systematic review and meta-analysis of randomized clinical trials according to PRISMA statement. Medicine (Baltimore). 2016 Jul;95(30): e4071. doi: 10.1097/MD.0000000000004071.

Rod Tucker

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