Inspiratory muscle strength training lowers blood pressure

29th September 2022

Inspiratory muscle strength training significantly reduced both systolic and diastolic blood pressure according to a review of 5 studies

Inspiratory muscle strength training (IMST) for a period of six weeks results in a significant reduction in both systolic and diastolic blood pressure compared to sham strength training according to a review of studies by US researchers.

Elevated systolic blood pressure is a leading cause of global deaths, accounting for 10·4 million deaths and 218 million disability-adjusted life-years. Lifestyle interventions to lower blood pressure include increased physical activity, weight loss and adoption of a healthy (lower salt) diet.

Another intervention which has gained interest in recent years is inspiratory muscle strength training which has been previously used to help wean patients off mechanical ventilation in hospital. Moreover, IMST has also been shown to be of some value by increasing peak power in recreational cyclists. Nevertheless, IMST has also been shown to reduce blood pressure and autonomic cardiovascular control in hypertensive patients.

In recent years, high-resistance low volume inspiratory muscle strength training which involves 30 daily inspiratory efforts against a resistance equal to 75% of an individual’s maximal inspiratory pressure, has emerged as a time-efficient lifestyle intervention (requiring only 5 minutes) to lower blood pressure. The technique has already been shown to lower blood pressure and may potentially improves vascular endothelial function.

Nevertheless, to date, most blood pressure lowering studies have only included a small number of participants. Consequently, for the present study, the US researchers pooled data from 5 randomised trials to provide a better estimate of the blood pressure lowering effect of IMST.

The trials included young adults, some of whom were taking blood pressure lowering medication but who overall had a low-to-moderate cardiovascular disease risk. Individuals were randomised to either high-resistance IMST or low-resistance (or sham) IMST and each of the trials lasted 6 weeks.

Participants performed 30 inspiratory efforts every day as a single bout, comprising 5 sets of 6 inspiratory efforts.

Inspiratory muscle strength training and blood pressure changes

Data from 128 adults were included of whom 67 with a mean age of 50 years (43.2% female) were assigned to high-resistance IMST and the remainder a sham procedure.

After 6 weeks, systolic blood pressure remained unchanged in the sham group but decreased from a mean of 127 mmHg to 118 mmHg in the high resistance IMST group and this difference was statistically significant (p < 0.01). In addition, systolic blood pressure was observed to decline by an average of 1.5 mmHg per week.

After 6 weeks, the mean diastolic pressure was also significantly lower in the high resistance IMST group (72 vs 76 mmHg, p < 0.01) and significantly lower than for the sham procedure which also reduced by a mean of 1 mmHg (p = 0.03).

The maximal inspiratory pressure (which is a measure of the strength of the inspiratory muscles, in particular the diaphragm) improved in both groups, but to a significantly higher level for the high resistance group (20 cmH₂O vs 6 cmH₂O, p < 0.01).

The authors noted that reductions in both systolic and diastolic pressures also occurred for those taking antihypertensive medication but that the effect was smaller.

They concluded that high resistance IMST induced clinically meaningful reductions in blood pressure and provide support for this technique as a time-efficient lifestyle intervention to lower blood pressure.

Citation
Craighead DH et al. A multi-trial, retrospective analysis of the antihypertensive effects of high-resistance, low-volume inspiratory muscle strength training J Appl Physiol (1985) 2022

Hypertension self-management successful with mobile technology

21st October 2021

Hypertension self-management can be successfully achieved over a three year period through harnessing the support of mobile technology

The use of mobile technology can support hypertension self-management in patients with the condition, according to the findings of a three-year study by a group from the Department of Epidemiology & Biostatistics, University of California, California, US. Hypertension is a global problem with the World Health Organisation (WHO) estimating that it affects 1.28 billion adults aged 30-79 years. However, perhaps of greater concern, is the WHO statistic that only 1 in 5 adults (21%) with hypertension have their condition under control.

Although self-monitoring can lead to reductions in blood pressure (BP) over and above usual care, a 2017 systematic review concluded that self-monitoring alone is not associated with lower BP or better control but that it requires co-interventions such as education or lifestyle counselling, to achieve clinically significant reductions which persist for at least 12 months. The use of mobile technology in the form of smartphone health apps, have been suggested a method to enable effective self-management of hypertension. Yet despite this potential role, a 2018 review of such apps concluded that although available studies do suggest a reduction in blood pressure among those using health apps, the conclusion should be interpreted with caution, since many studies were at high risk of bias.

Given the high risk of bias and the importance of co-interventions, the Californian team used a smartphone app in conjunction with BP monitoring that included digital-based coaching to help support hypertension self-management. Participants were US adults with elevated BP recruited through an employer-based health plan. Blood pressure was measured using an FDA approved Bluetooth-enabled monitor paired with the smartphone app which also allowed participants to track their weight and levels of physical activity. The app included medication reminders and coaching to drive lifestyle changes based on usage patterns to personalise the advice. At baseline, participants were categorised in terms of their systolic BP as: normal and < 120 mmHg; systolic between 120 and 129 mmHg; systolic between 130 and 139 (stage 1 hypertension) and finally a systolic > 140 mmHg (stage 2 hypertension). Blood pressure measurements (both systolic and diastolic) were evaluated in the first week (week 0) and then several times up to weeks 148 to 163.

Findings

A total of 28,189 individuals with a median age of 51 years (59.6% male) were included in the hypertension self-management study. After 3 years, median systolic blood pressure was reduced in 53.7% of those with a systolic BP between 120 and 129 mmHg, 75.3% of those with stage 1 hypertension and in 84.4% of those with stage 2 hypertension. Similarly, after 3 years, the mean reductions in diastolic BP were -4.4 mmHg, -6.8 mmHg and -11.6 mmHg respectively.

A subgroup of 3,229 participants recorded their body mass index (BMI) and for each unit reduction in BMI, there was a 0.74 mmHg decrease in systolic BP. Similarly, among 590 individuals who recorded their physical activity, for each 1000-step increase per day, there was a 0.8 mmHg lower systolic BP (P = 0.03).

The authors concluded that their hypertension self-management program supported by mobile technology, achieved long-term control of BP, suggesting that this approach may be useful for BP monitoring and control.

Citation

Gazit T et al. Assessment of Hypertension Control Among Adults Participating in a Mobile Technology Blood Pressure Self-management Program. JAMA Netw Open 2021

Intensive blood pressure control in the elderly reduces cardiovascular outcomes

3rd September 2021

Intensive blood pressure control in elderly Chinese patients has been found to reduce the incidence of adverse cardiovascular outcomes.

High blood pressure is an important risk factor for both cardiovascular and chronic kidney disease. As a result, blood pressure treatment guidelines have made recommendations, particularly for target systolic blood pressure values.

There is evidence that lowering this component reduces the risk of cardiovascular disease and all-cause mortality and the current systolic blood pressure target set by the European Society of Cardiology is 130 to 139 mmHg.

#While lowering systolic pressure further to under 120 mmHg in those aged 75 years and older, reduced the incidence of fatal and non-fatal major cardiovascular events, other data has found an increased mortality risk among the elderly.

Given these ambiguities, a Chinese team from the Hypertension Centre, FuWai Hospital, Peking, China, performed a randomised, controlled trial, in hypertensive patients aged 60 to 80 years of age.

They included patients with a baseline systolic pressure of between 140 and 190 mmHg for at least three months prior to the study.

The study examined the outcomes associated with reducing systolic blood pressure to a target of 110 to less than 130 mmHg (the intensive treatment) or a target of between 130 and less than 150 mmHg (standard treatment).

All patients were provided with a home blood pressure monitoring device and were required to provide readings at least weekly during the follow-up period.

The primary outcome of interest was a composite of several adverse cardiovascular events including stroke, acute coronary syndrome and hospitalisation for unstable angina, atrial fibrillation and death from cardiovascular causes.

Findings

A total of 8511 patients were randomised to either arm with a mean age of 66.2 years (46.9% male) and a mean systolic blood pressure of 146.1 and a diastolic of 82.7 mmHg.

During a median follow-up of 3.34 years, the primary outcome occurred in 3.5% of those in the intensive blood pressure arm and 4.6% in the standard arm (hazard ratio, HR = 0.74, 95% CI 0.60 – 0.92, p = 0.007).

Furthermore, the individual components of the primary outcome were also significantly improved in the intensive arm.

For example, the hazard ratio for stroke was 0.67 (95% CI 0.47 – 0.97), acute coronary syndrome (HR = 0.67) and although death from any cardiovascular cause was reduced, this was not significant (HR = 0.72, 95% CI 0.39 – 1.32).

There were also no differences in safety outcomes such as hypotension, dizziness, syncope or fracture and for renal outcomes.

The authors concluded that intensive blood pressure lowering among elderly patients was associated with a reduced risk of adverse cardiovascular outcomes.

However, a recognised limitation was that it was undertaken in a Chinese population which could reduce the generalisability of their findings and that the study excluded patients with a history of stroke.

Citation
Zhang W et al. Trial of Intensive Blood-Pressure Control in Older Patients with Hypertension. New Eng J Med 2021.