All individuals with cardiovascular disease should be encouraged to participate in an active lifestyle, incorporating recreational, domestic and vocational activities as their symptoms allow.

Patients recovering from a cardiac event, HF exacerbation or those who have stable disease but are sedentary, should gradually increase their level of physical activity to the recommended intensity. That is, aiming for 150 minutes of moderate intensity exercise per week, which equates to 30 minutes, most days of the week.  For those with good exercise tolerance, additional health benefits accrue from daily activity of up to 60 minutes. Those who find extended periods of continuous exercise difficult may tolerate breaking down exercise into smaller intervals such as 10 minute intervals.

For some individuals, attaining recommended levels of physical activity may be challenging. For these patients, encouragement and support to reduce sedentary behaviour and to replace this with light intensity activity, may prove an achievable starting point. Gradual progression of duration and intensity of activity may then be possible.

TIP: Activity feedback from watches and smart phones may be useful to help motivate patients.  Walking for 30 mins/day plus normal activity equates to 7000-10,000 steps per day.

Exercise prescription is characterised by the following variables, known as the FITTP principle:

• Frequency – the number of times exercise is performed per week
• Intensity – how hard the exercise is
• Time (duration) – the total time of an exercise session
• Type – the mode of exercise
• Progression – how the exercise is progressed to continue to provide a training stimulus

The total amount (dose) of exercise is a function of its intensity, duration and frequency. This total quantity is the main determinant of outcomes. Exercise prescription must consider these variables in combination as they influence both potential training adaptation and the level of fatigue to be expected.

Exercise intensity is often described as being low, moderate or vigorous. The table below (adapted from ACSM guidelines) indicates exercise intensity according to RPE and heart rate reserve (HRR), whereby HRR = THR = [(HRmax – HRrest) x % intensity] + HRrest.

The Fick equation (see below) is used to identify the various components of oxygen consumption and therefore energy expenditure during physical exertion. The Fick equation can help identify the limitations of physical exertion.

Oxygen consumption (VO2) = Cardiac output (CO) x arteriovenous oxygen difference (a-VO2)

An adequate warm-up and cool-down before and after each session reduces the risk of adverse events during exercise.

• Warm-ups aid the gradual transition from a state of rest to the increased physiological demand associated with exercise, encompassing increased skeletal muscle perfusion and thermoregulatory mechanisms. Warm-ups may reduce the likelihood of ST-segment depression, arrhythmias, and transient left ventricular dysfunction
• Cool-downs allow the HR and blood pressure to return to resting values. Cool downs reduce venous pooling of blood in the active musculature and reduce the risk of arrhythmias, post-exercise hypotension, dizziness and catecholamine surges

TIP: Adequate warm-up and cool-down periods are essential elements of a safe exercise prescription.

Walking performance on a six-minute walk test(6MWT) gives a good indication of exercise tolerance and helps guide initial exercise prescription for ground or treadmill walking.

Walking training intensity is calculated based on both the distance walked and the Rating of perceived exertion reached at the conclusion of the 6MWT.

Walking speed calculation:

• Rating of perceived exertion ≤11 (‘fairly light’); prescribe walking training at 100% of the walking speed during the 6MWT
• Rating of perceived exertion 12-14 (‘somewhat hard’); prescribe at 90% of the walking speed during the 6MWT
• Rating of perceived exertion ≥14 (‘hard’); prescribe at 80% of the walking speed during the 6MWT

This assumes an absence of ischaemic symptoms, peak HR <120 beats per minute and initial walking duration of 10-15 minutes.

6MWT average speed is calculated as shown below:

• 6MWT average speed = (6MWT distance x 10) ÷ 1000 km / hr

Average 6MWT speed calculation

TIP: Set the initial treadmill speed 0.5-1.0 km/hr slower than calculated if the patient is unfamiliar with walking on a treadmill. Once the patient has become confident, increase to the calculated walking speed.

Note: HF symptoms may vary from week to week. Assess at each attendance and adjust prescribed exercise accordingly.

Some exercise programs have both indoor and outdoor walking options. Indoor exercise, where monitoring and access to assistance is more rapidly accessible, is usually more appropriate for frailer patients and those at higher CV risk.

Which Borg Scale?

The rating of perceived exertion (RPE) is commonly used to monitor and prescribe exercise intensity.

The original Borg Scale ranged from 6-20 and was developed to correlate with HR.

The modified Borg Scale is a category ratio on a scale of 0-10.

Both scales are widely used, and no guidelines exist recommending the use of one over the other.

Aerobic exercise involves low-to-moderate intensity rhythmic movement of large muscle groups for an extended period of time. Aerobic exercise should be encouraged on most days of the week. When prescribing aerobic exercise, the following should be considered:

• During each session, warm-up and cool down activities of 5-10 minutes at a low intensity should be performed
• Shorter duration and more frequent rest periods may be required for those with frailty or severe symptoms
• The chosen mode of aerobic exercise should be one that an individual enjoys and tolerates without pain or residual fatigue. Regularity of physical activity is a significant part of attaining the cardiovascular benefits.
• The individual’s clinical status, risk stratification status, exercise capacity, angina threshold, musculoskeletal limitations and cognitive/psychological impairment will all influence safety and participation in the prescribed exercise
• Exercise tolerance will vary between individuals. Consider using equipment/machines that utilise either upper limb or lower limb muscles for individuals with reduced exercise tolerance. For example, an exercise bike which predominantly works only the lower limb muscles, uses less total muscle mass than a rowing machine, which employs both upper limb and lower limb muscles. 
• Exercise prescription should begin conservatively. For supervised programs, patients should be closely observed, and response to exercise training reviewed at each subsequent session.
• Exercise intensity for patients with HF or CVD is often based on perceived exertion rather than target HRs because cardiac medications can affect HR. Few patients will have had maximal graded exercise testing prior to referral.
• For home-based or virtual programs, initial exercise intensity may need to be reduced slightly due to the absence of immediate medical assistance.
• In people with heart failure, latent fatigue is common after exercise, and may not be experienced until later in the day or the following day. Reducing intensity and intermittent exercise may be beneficial if this occurs.
• Consider high intensity training 1-3 x week in select patients.

Exercise guidelines for people with cardiac conditions should be considered in the context of the F.I.T.T.P principles as outlined below.

High Intensity Interval Training (HIIT)

High intensity interval training (HIIT) is broadly defined as intermittent periods of intense exercise (more than usual) separated by periods of rest. This is recommended in select patients on the basis that increasing exercise intensity is known to result in positive health benefits.  In detrained individuals, this may include periods of brisk walking, alternated with periods of walking at a reduced pace (1). In patients with HF, many ADLs can require efforts equivalent to a vigorous intensity.

Caution and careful clinical judgement should be taken when considering HIIT prescription in the clinical setting for patients with cardiac conditions. Studies suggest commencing conservatively. For example, start with short interval durations (1-2 minutes) and progress to longer interval durations (3-4 minutes) as exercise intolerance and fitness improves.  Additionally, exercise intensity should be progressed from low-moderate intensity to moderate-vigorous intensity before commencing HIIT, to assess the exercise response, improve exercise tolerance and physical fitness, and minimize musculoskeletal injuries.[#taylor-j-myers-j-bonikiwske-a.-2023.-practical-guidelines-for-exercise-pres]

Exercise training and heart failure with preserved ejection fraction (HFpEF)

The optimal dose of physical activity (+/- exercise) that is beneficial to reduce adverse outcomes in patients with HFpEF is unknown. However, any increase in the amount of physical activity, regardless of intensity, is known to contribute to health benefits (1). The overall aim for these patients should therefore be to attain, and progressively accumulate more than 150 minutes of moderate intensity activity per week. Exercise interventions for these individuals should follow the same above ‘general guidelines for individuals with Heart Failure’. [#schmidt-c-moreira-goncalves-d-santos-m-leite-moreira-a-et-al.-physical-acti]

Resistance exercise training involves exerting muscular force to move a body segment or an external resistance, such as a weight or resistance band. This is the best form of exercise for increasing skeletal muscle mass and strength. Resistance exercise training complements aerobic training in augmenting exercise capacity and may play an important role in improving body composition (including decreased fat mass), vascular endothelial function and cardiac autonomic regulation. It also improves the performance of routine daily living activities requiring muscular strength and endurance, such as carrying groceries, gardening and cleaning, and therefore has beneficial effects on self-efficacy and health-related quality of life.

A loss of skeletal muscle mass, strength and function (collectively defined as sarcopenia) is common in individuals with cardiac conditions, especially the elderly and those with more advanced disease and frailty. Sarcopenia is associated with a reduced quality of life and is an independent predictor of cardiovascular mortality. The pathophysiology of skeletal muscle abnormalities in cardiovascular disease, such as coronary artery disease and heart failure, is complex and multifaceted and includes chronic low-grade systemic inflammation, endocrine abnormalities, mitochondrial dysfunction and oxidative stress. This is further compounded by disuse muscle atrophy due to physical inactivity and an abnormal exercise pressor response and neurocirculatory control.  In light of this, resistance training is now an important focus of standard care for cardiac and heart failure rehabilitation programs.

Historically, concerns about abrupt increases in blood pressure, heart rate and cardiac output, limited the inclusion of resistance exercise in cardiac rehabilitation programs.   However, this response can be mitigated by taking into account influencing factors such as the magnitude of the isometric contraction, amount of muscle mass involved, number of repetitions and/or duration of loading and length of rest periods between sets. Moreover, it has been demonstrated that the haemodynamic responses during low to moderate intensity resistance exercise (40-60% one-repetition maximum, 15-20 reps) is comparable to moderate intensity aerobic exercise.

Availability of equipment will often guide resistance exercise prescription.

Equipment may include:

• Body weight/body segments
• Free weights
• Resistance machines
• Isokinetic machines
• Resistance bands

The minimum frequency to improve strength is a single set performed twice a week. As training progresses, patients may need to train more frequently and increase the number of repetitions and sets. Resistance exercise should be combined with an aerobic exercise program, so it is important to ensure the time required to undertake all of the exercises is consistent with the patient’s level of commitment and health status.

When prescribing resistance exercise, the following are recommended:

• Initiate resistance training under direct supervision with close monitoring
• Initiate resistance loads conservatively and ensure good technique to avoid injury
• Commence untrained or higher-risk patients with 1-2 weeks of aerobic training prior to commencing resistance training
• Encourage appropriate breathing techniques to avoid Valsalva manoeuvre
• Aim initially for 12-25 reps at low intensity (RPE 12-13) to increase muscle endurance before progressing the intensity
• When the patient is confident, progress to higher intensities (RPE < 15) at 8-15 reps, emphasising increased muscle mass
• Ensure mostly dynamic muscle action rather than isometric exercises
• Include 8-10 exercises to engage major functional muscle groups of the upper and lower body
• For patients with advanced CVD, prescribe exercises that involve single joints and are isolated to a smaller muscle mass

TIP: A comprehensive exercise program should incorporate both aerobic and resistance exercise. Including both exercise modalities can result in superior clinical outcomes such as muscle strength, exercise capacity and quality of life.

Adults with cardiovascular disease have a high risk of falling due to medications, postural hypotension, structural heart disease, arrhythmias and frailty. For patients with CVD wo fall, the consequences can be significant, particularly for those prescribed anti-coagulation medications. For this reason, activities which improve balance and flexibility may be recommended to reduce risk of falls and to improve functional mobility.  Examples of activities which may help to improve balance include:

• Static and dynamic stance exercises
• Balance games/ apps (eg., “Clock yourself”)
• Lower limb strength training
• Tai chi
• Stretching exercises for shortened muscles which may impact upon gait and balance

Respiratory (inspiratory) muscle training is particularly useful for people who have respiratory muscle weakness. Inspiratory muscle trainers, such as the one shown below, provide resistance as the individual breathes in, thereby providing a training stimulus to the respiratory muscles. Specific protocols determine the appropriate level of resistance. In patients with HF, respiratory muscle training has been shown to elicit additional gains in 6MWT and VO₂ peak in those with respiratory muscle weakness.

‘Powerbreathe’ inspiratory muscle trainer

Reproduced with permission from Powerbreathe International

Functional electrical stimulation (FES) is an adjunct to exercise training for patients who are extremely unwell or deconditioned (i.e., NYHA class III or IV). FES is a passive therapy, where a small electrical current is passed through a targeted muscle (usually quadriceps), stimulating a muscle contraction. The effect is improved muscle function similar to that which occurs after exercise training.

FES has been shown to improve exercise capacity and quality of life though does not appear to improve muscle strength. It may help maintain fitness during periods of severe HF decompensation and subsequently assist in returning a patient to a level of function that allows the recommencement of a low-intensity cycling or walking exercise. FES may be contraindicated in those with an implantable cardiac device.

Example of functional electrical stimulation (FES) machine

Reproduced with permission from Astir Australia