Isometric Handgrip Training Frequency and Blood Pressure in People With Hypertension

Official title

The Dose Response Effect of Isometric Handgrip Training Frequency on Blood Pressure and Vascular Health in People With Hypertension: A Randomised Controlled Trial

Overview

Hypertension is the most important cause of cardiovascular disease (CVD), stroke, and premature death (WHO, 2021). It is estimated by The World Health Organisation in 2021 that 1.4 billion individuals across the globe have high blood pressure, with only 14% of people actively managing these elevated levels. Simple and effective lifestyle strategies are required to help people improve their blood pressure and/or attenuate increases in blood pressure with ageing. Physical activity is one possible strategy: in previous research, several different types of physical activity have been shown to have beneficial effects on blood pressure (Blackwell et al., 2017). However, many individuals do not adhere to currently recommended levels of physical activity (150 mins of moderate intensity physical activity per week), due to a combination of the required time commitment, lack of motivation, and the associated levels of effort, exertion, and physical discomfort (Korkiakangas et al 2009). Thus, there is a need to identify alternative exercise interventions which will overcome these barriers but remain effective at improving blood pressure (Herrod, Lund, \& Phillips, 2021, Toohey et al, 2018). Low intensity isometric hand grip exercise training (IET) has been shown to result in large decreases in resting blood pressure in younger and older age groups, in both men and women, and in individuals with normal as well as elevated baseline blood pressure (Badrov et al, 2013; Bentley et al., 2018; Millar et al., 2014). In this research, IET has almost universally involved performing 4 x 2 IET holds at 30% of maximal voluntary contraction, 3 times a week, over a 4-8-week intervention (Millar et al, 2014). There are very few studies that have investigated the effect of changing different protocol parameters on changes in blood pressure and vascular health, and the minimal effective dose of IET is unknown. Defining the minimal effective dose of different types of exercise may help overcome key barriers to exercise by lowering the required time commitment, reducing perceived effort/exertion, and promoting more positive affective responses. One important modifiable parameter is training frequency and it is unknown whether reducing the frequency of IET will reduce the efficacy for improving blood pressure. Therefore, the primary objective of this study is to determine if reducing the frequency of isometric handgrip training from four times a week to two times a week will affect the improvements in resting blood pressure and vascular health in people with hypertension. A secondary objective is to investigate the acute affective and perceptual responses to sessions of IET and the effect of training on these acute affective/perceptual responses.

Interventions

• Other Exercise Training (Isometric Handgrip Exercise)
  Participants allocated to the exercise groups will complete 6 weeks of isometric handgrip exercise training (IHGT) using an electronic hand dynamometer (Camry EH101, Zhongshan Camry Electronic Co. Ltd, Guangdong) for either 2 or 4 sessions per week. Each exercise session will consist of 4 x 2-minute isometric contractions at 30% MVC with 1 minute rest periods between contractions. The first bout will be performed on the dominant arm and then the arm will be alternated for each subsequent two-min

Primary outcome measures

• Office measured supine and seated systolic, diastolic and mean arterial pressure [Time frame: 6 weeks]

Secondary outcome measures (7)

• Office measured central systolic, diastolic and mean arterial pressure [Time frame: 6 weeks]
• 24-h mean ambulatory systolic, diastolic, and mean arterial pressure [Time frame: 6 weeks]
• Daytime ambulatory systolic, diastolic, and mean arterial pressure [Time frame: 6 weeks]
• Sleeping ambulatory systolic, diastolic and mean arterial pressure [Time frame: 6 weeks]
• Carotid-Femoral Pulse Wave Velocity [Time frame: 6 weeks]
• Affective Valence (Feeling Scale) [Time frame: 6 weeks]
• Ratings of perceived exertion [Time frame: 6 weeks]

Eligibility criteria

Inclusion criteria

• Aged between 18 and 65 years.
• Scoring low or moderate on the international physical activity questionnaire (IPAQ).
• Previous diagnosis of high blood pressure and/or a resting systolic blood pressure ≥130 but <180 mmHg (self-reported and confirmed during screening/baseline assessment).
• Currently taking no anti-hypertensive medicine or taking anti-hypertensive medicine with no treatment change within the last 4 months prior to enrollment.
• Stable dietary and physical activity patterns (including dietary supplementation) over the last 4 months

Exclusion criteria

• Aged <18 or >65 years
• Resting blood pressure ≥180/110 mmHg or resting heart rate >100 bpm during baseline as-sessment
• Manifest cardiovascular disease including cerebrovascular disease, heart failure, chronic kidney disease, peripheral vascular disease, or advanced retinopathy (fundus hypertonicus grades III-IV) based on a self-report health history questionnaire.
• Type 1 diabetes
• History of other chronic disease including malignancy, neurological conditions (e.g. multiple sclerosis) or respiratory conditions (e.g. COPD).
• Contraindications to exercise based on answers to the physical activity readiness questionnaire.
• Physical limitations preventing handgrip exercise (e.g. arthritis or other musculoskeletal disorder)
• Scoring "high" on the international physical activity questionnaire
• Taking more than 2 anti-hypertensive drugs or a change in treatment strategy in the previous 4 months.
• Currently taking nitrate medication (as it is commonly prescribed for angina) or on hormone replacement therapy
• Significant self-reported change in lifestyle patterns in the prior 4 months (e.g. currently on a planned diet for weight loss).

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Allocation

Randomized

Model

Parallel assignment

Masking

Open label

Primary purpose

Treatment

Study locations

United Kingdom · 1 center

• Swansea University — Swansea

Identifiers

NCT: NCT06335433 · RM_30_06_22b

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗