Isometric Handgrip Training Frequency and Blood Pressure in People With Hypertension

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

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.

Study Overview

• Status: Recruiting
• Conditions: Hypertension
• Intervention / Treatment: Other: Exercise Training (Isometric Handgrip Exercise)

• Study Type: Interventional
• Enrollment (Estimated): 45
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Richard Metcalfe, PhD; Phone Number: 4779 01792205678; Email: r.s.metcalfe@swansea.ac.uk

Study Locations

• United Kingdom
  • Wales
    • Swansea, Wales, United Kingdom, SA18EN
      • Recruiting
      • Swansea University
      • Contact: Richard Metcalfe, PhD; Phone Number: 4779 01792205678; Email: r.s.metcalfe@swansea.ac.uk

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

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).

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
No Intervention: No Intervention Control; Participants will be asked to maintain their normal lifestyle patterns (i.e. diet and physical activity) and will undergo no other intervention.
Experimental: Two Sessions/Week; Participants will complete 6-weeks of supervised isometric handgrip exercise training with a frequency of two sessions/week	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-minute bout. Participants will be instructed to try keep the contraction tension as close as possible to the set tension of 30% MVC using visual feedback from the dynamometer's electronic display.
Experimental: Four Sessions/Week; Participants will complete 6-weeks of supervised isometric handgrip exercise training with a frequency of four sessions/week	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-minute bout. Participants will be instructed to try keep the contraction tension as close as possible to the set tension of 30% MVC using visual feedback from the dynamometer's electronic display.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Office measured supine and seated systolic, diastolic and mean arterial pressure	Office measured supine and seated systolic, diastolic and mean arterial pressure will be measured at baseline and 3 days following the final exercise session	6 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Office measured central systolic, diastolic and mean arterial pressure	Office measured central systolic, diastolic and mean arterial pressure will be measured at baseline and 3 days following the final exercise session	6 weeks
24-h mean ambulatory systolic, diastolic, and mean arterial pressure	24-h mean ambulatory systolic, diastolic, and mean arterial pressure will be measured at baseline and 3 days following the final exercise session	6 weeks
Daytime ambulatory systolic, diastolic, and mean arterial pressure	Daytime ambulatory systolic, diastolic, and mean arterial pressure will be measured at baseline and then 3 days following the final exercise session	6 weeks
Sleeping ambulatory systolic, diastolic and mean arterial pressure	Sleeping ambulatory systolic, diastolic and mean arterial pressure will be measured at baseline and then 3 days after the final exercise session	6 weeks
Carotid-Femoral Pulse Wave Velocity	Carotid-Femoral Pulse Wave Velocity will be measured at baseline and then 3 days after the final exercise session	6 weeks
Affective Valence (Feeling Scale)	Affective valence will be measured at regular intervals during the isometric handgrip exercise sessions. Ratings will be collected during the first session and then during the final session of each training week.	6 weeks
Ratings of perceived exertion	Ratings of perceived exertion will be measured at regular intervals during the isometric handgrip exercise sessions. Ratings will be collected during the first session and then during the final session of each training week.	6 weeks

Collaborators and Investigators

• Sponsor: Swansea University
• Investigators: Principal Investigator: Richard Metcalfe, PhD, Swansea University

Study record dates

Study Major Dates

• Study Start (Actual): March 20, 2024
• Primary Completion (Estimated): March 1, 2026
• Study Completion (Estimated): March 1, 2026

Study Registration Dates

• First Submitted: March 21, 2024
• First Submitted That Met QC Criteria: March 21, 2024
• First Posted (Actual): March 28, 2024

Study Record Updates

• Last Update Posted (Actual): March 28, 2024
• Last Update Submitted That Met QC Criteria: March 21, 2024
• Last Verified: March 1, 2024

More Information

Terms related to this study

• Keywords: High Blood Pressure; Vascular Health; Dose Response; Isometric Handgrip Exercise; Training Frequency; Perceptual Responses
• Additional Relevant MeSH Terms: Cardiovascular Diseases; Vascular Diseases; Hypertension
• Other Study ID Numbers: RM_30_06_22b

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No