Why we do what we do

The therapeutic effects of exercise in the prevention, management and treatment of cardiovascular disease have been recognized for over half a century. Exercise has therefore become a significant tool in both clinical medicine (for example cardiac rehabilitation and exercise referral programmes) and in public health (for example ‘Change 4 Life’ and the Ride to Work scheme).

Whilst clinical exercise such as cardiac rehabilitation is often conducted under the direct supervision of an exercise physiologist and prescribed in quantities and durations not unlike drug therapies, public health applications of exercise are often vague, centering on messages such as ‘move more’ and ’do 30 minutes of exercise 5 times a week’. Given that across the population there is huge diversity in health status, fitness levels, prior experience with exercise and many other related factors, GPs and patients alike are often left a little confused as to which type, intensity, duration and frequency of exercise to use in relation to the needs of specific conditions or goals.

There is also an all too evident ‘aerobic orthodoxy’ in public health, in which nearly all promotion materials focus on aerobic activities such as walking, running, swimming and cycling. Whilst the health benefits of such activities are indisputable, this orthodoxy has traditionally ignored the significant potential benefits of resistance or weight training. This is perhaps understandable given that resistance training generally requires both specialized equipment and expertise. However, this is not true of all approaches, and certain types of resistance exercise, for example isometric exercise training (IET), not only requires no equipment and little expertise, but can be performed in the home in relatively short duration sessions (10-15 minutes). Isometric exercise training thereby, also overcomes one of the major barriers to exercise at the population level, lack of time.

The aim of our group is to examine the efficacy and effectiveness of IET in reducing blood pressure among normal, preclinical and clinical populations. In doing so we aim to increase the range of treatment options open to both patients and clinicians. This is an especially important aim given the side effects to drugs experienced by many patients and the resultant high rates of non-compliance. Further, unlike antihypertensive medication, as is the case with other forms of resistance exercise training IET is likely associated with wider ranging benefits.

Isometric (iso=same, metric=measure) exercise is where muscles are made to contract, but no discernible movement occurs. A good example of an isometric muscle contraction is holding onto a support bar on a moving train; your muscles have to tense significantly, but they do not actually cause any movement (in tensing your muscles in this situation you are in fact trying to oppose any destabilising movements). Examples of isometric exercises often used in fitness settings are; holding a press up, squat or plank position (please see below) for a given period of time such as 20 seconds.

isometric press up

isometric wall squat


Isometric exercise training (IET) is the systematic use of isometric exercise in an evidence-based and scientifically sound programme specifically designed to achieve certain physiological adaptations, such as improving strength or muscular endurance.

The use of IET as a potential health treatment was not developed specifically by scientists, but as is so often the case, was initially observed in the context of our everyday activities. Specifically, the observation that there was a lower incidence of hypertension (high blood pressure) amongst men in jobs which involved moderate or heavy isometric activity (e.g. gripping to lift objects) regardless of age, social class, body composition or alcohol intake (Buck and Donner, 1985). 

This seminal work threw down the gauntlet for researchers all over the world to further explore the potential antihypertensive benefits of isometric exercise.

Over the last decade, the main focus of our work in this area has been to investigate the effects of different isometric exercise training protocols upon blood pressure with the ultimate goal of providing both a prophylactic for those at risk of developing hypertension and an effective treatment for those already suffering from hypertension. Indeed, our findings increasingly support the contention that IET can provide a viable alternative for many individuals facing a lifetime of antihypertensive medication.  

Whilst most people are aware that a number of lifestyle modifications are effective in the prevention and treatment of high blood pressure (NICE Guidelines 2011), it has recently been suggested that the role of physical activity is paramount (Carlson et al., 2014). For those who already appreciate this, aerobic exercise (e.g. jogging for 30 minute) is arguably the form of exercise most likely to be associated with antihypertensive benefits (Mancia et al., 2007). However, recent meta-analytic findings indicate that, when compared with aerobic exercise, which reduced resting SBP by 3.5 mmHg and DBP by 2.5 mmHg, IET resulted in significantly greater reductions of 10.9mmHg and 6.2 mmHg respectively (Cornelissen and Smart, 2013). To contextualise these findings, as little as a 2mmHg reduction in SBP or DBP can decrease the risk of hypertension by 17%, coronary heart disease by 5-6%, stroke by 15%, and all-cause mortality by 3% (Cook, Cohen, Hebert, Taylor and Hennekens, 1995; Stamler, 1997). In short, IET could be a very important treatment for hypertension.

In addition to this, and perhaps more saliently, IET is associated with a number of added psychosocial benefits, such as short exercise duration, ease of use, and unrestricted access, which collectively reduce some of the significant barriers to regular physical activity (Carlson 2014).

To date, our research group have demonstrated that resting blood pressure can be significantly reduced in normotensive participants following 8 weeks IET (Wiles et al., 2010) and then with as little as 4 weeks IET (Devereux et al., 2010) using bilateral leg extension. Our findings suggest that the efficacy of IET as a form of antihypertensive therapy is based upon the complex interaction of acute programme variables such as target muscles used, type of exercise, contraction style, exercise intensity, progressive overload and the integration of both short (between bouts) and long (between sessions) term recovery. These have been investigated extensively in healthy normotensive participants (Wiles et al., 2010; Devereux et al., 2010; Devereux et al., 2011; Devereux et al., 2012, Baross et al., 2012; Baross et al., 2013; Goldring, 2014; Devereaux et al.) to provide the necessary foundation for IET to be accurately and safely prescribed to the hypertensive population.

The search for the most effective isometric exercise training prescription has led us to explore a number of novel isometric exercise protocols (Wiles et al., 2005; Wiles et al. 2008; Wiles et al., 2010; Goldring et al., 2014,) with a special focus on prescribing this type of exercise in non-laboratory settings such as the home (Wiles et al., 2016). Indeed, in order to further facilitate isometric exercise prescription in the home we are also currently exploring the efficacy of prescribing wall squat intensity (angle) based upon an individual’s rating of perceived exertion (RPE) (John Lea, PhD.). This would allow the safe and reliable prescription of IET without the need for prior laboratory or medical testing or screening.

Our most recent findings demonstrate that 3 sessions of 4 x 2-minute isometric wall squat exercise performed at 95% of HRpeak (as ascertained during an incremental isometric walls squat test; Goldring, et al., 2014) over 4-week total training period, results in a statistically significant reduction in all parameters of resting and ambulatory blood pressure in pre-hypertensive participants (Taylor et al., 2018). Furthermore, exercising blood pressure for both diastolic (<115 mmHg) and systolic (<250 mmHg) stayed consistently within the ACSM exercise termination guidelines (Whaley et al., 2006) for all participants indicating the training protocol is also, relative to other forms of exercise, safe for use with a sub clinical (and potentially clinical) participant group. At present we are exploring the acute physiological responses to IE and the longer term adaptations to IET in female populations who are significantly underrepresented in the literature.

The mechanisms responsible for the observed reductions in resting blood pressure following IET are currently under investigation. However, reductions in blood pressure must be a result of changes in cardiac output and/or peripheral vascular resistance, as these are the two factors that determine mean arterial blood pressure. Prior research has demonstrated alterations in factors modulating cardiac output or peripheral vascular resistance alone, but not in combination. However, although the methods assessing responses in peripheral vascular resistance have been robust, assessment of cardiac function has not been studied in detail. To our knowledge, we are the first group to directly investigate the effect of IET on chronic adaptations in cardiac structure, function and mechanics, in combination with assessing changes in peripheral vascular resistance. Early indications are that the large reductions in resting blood pressure observed in our latest study may be due in part to improved autonomic function, cardiac mechanics, and reduced peripheral vascular resistance. Further to this, we have also shown that IET conveys broader cardiovascular benefits with significant improvements evident in inflammatory and vascular biomarkers (Taylor et al., 2018). However, the precise physiological and psychological isometric exercise stimuli and subsequent mechanism(s) leading to resting blood pressure reduction (regardless of initial blood pressure status) remain unknown.

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Last edited: 17/10/2019 09:59:00