Inclusion Criteria:  Aged 18 or over Clinic systolic BP 140-159 mmHg Able to provide informed consent  Exclusion Criteria:  Currently taking anti-hypertensive medication White coat hypertension, as evidenced by averaged home systolic BP <135 mmHg Inability to undertake study intervention (isometric exercise)  Previous history of any of the following:  Diabetes mellitus (Type 1 or type 2) Ischaemic heart disease (myocardial infarction and/or coronary angina and/or coronary revascularization procedure) Moderate or severe stenotic or regurgitant heart valve disease Atrial or ventricular arrhythmia Stroke or transient ischaemic attack Aortic aneurysm and/or peripheral arterial disease Uncorrected congenital or inherited heart condition Estimated glomerular filtration rate <45 ml/min (calculated using CKD-EPI or MDRD formulae, and taking most recent documented results) Documented left ventricular ejection fraction <45% and/or left ventricular hypertrophy (by either echocardiography or standard ECG criteria e.g. Sokolow-Lyon) Documented urine albumin:creatinine ratio >3.5 mg/mmol Inability to provide informed consent If female, pregnancy or currently breast feeding Enrolled in another Clinical Trial of an Interventional Medicinal Product or Medical Device or other interventional study Medical condition that, in the opinion of the investigator, would make the participant unsuitable for the study