Physical activity in the life of chronic kidney disease

When clinicians think of recovery after a cardiac event, exercise comes to mind, with cardiac rehabilitation being an integral component of secondary prevention. However, despite the well-established links between cardiovascular disease (CVD) and chronic kidney disease (CKD), when clinicians think of CKD, exercise is not always what first comes to mind. This represents a significant missed opportunity to improve physical, psychological, and emotional outcomes in patients with high rates of frailty and CVD risk factors in all stages of CKD. The Irish Longitudinal Study on Ageing (TILDA) revealed in 2023 that more than one-in-seven people over the age of 50 years in Ireland have CKD, and patients with hypertension or diabetes are up to three times more likely to have CKD. Physical activity and exercise can play a role in all stages of CKD, from initial diagnosis, to progression to end stage kidney disease (ESKD), and to life after kidney transplantation. However, currently in Ireland, a patient’s postcode dictates access to specially trained physiotherapists and they are only available in the acute hospital setting.

Lifestyle modification in the management of CKD

As is true for many medical conditions, there is not one singular treatment approach in the management of CKD that is used by every healthcare professional. There is a combination of approaches, including, but not limited to, dietary changes, pharmacological strategies, weight management approaches, blood pressure and blood glucose control, and exercise. Physical inactivity has been identified as an independent risk factor for the accelerated deterioration of kidney function, physical dysfunction, poor cardiovascular, respiratory and metabolic health, and lower levels of quality-of-life in people living with various stages of kidney disease. In addition, there is a beneficial relationship between exercise and hypertension, insulin resistance, and weight management. International nephrology guidelines recommend a healthy lifestyle to slow the progression of CKD, in which physical activity is a component.

More recently, Kidney Disease: Improving Global Outcomes guidelines also specifically recommend physical activity as a holistic treatment approach for patients with CKD, and hypertension or diabetes. The UK Renal Association published Clinical Practice Guidelines: Exercise and Lifestyle in CKD in 2022, bringing physical activity and exercise to the forefront for those living with kidney disease. The benefits of exercise in those living with kidney disease include improvements in blood pressure, physical function, functional limitations, and health-related quality-of-life. Research has also found that regular, well-designed, interactive, and multi-faceted combinations of educational and exercise interventions, including both individual and group settings, may improve knowledge, self-management, and encourage lifestyle changes in individuals with CKD.

Recommended physical activity levels

Physical activity and exercise are two concepts that are often used interchangeably in healthcare. Physical activity is defined as ‘any bodily movement produced by skeletal muscles that results in energy expenditure’. This includes participating in activities of daily living and hobbies such as gardening or playing a musical instrument. On the other hand, exercise is a type of physical activity which is ‘planned, structured, and repetitive with the goal of improving or maintaining physical fitness’. Some patients with CKD are physically active in their day-to-day activities, but don’t engage in formal exercise. Regular physical activity is important to reduce the comorbidities associated with a sedentary lifestyle. However, in order to get the optimal benefits, patients need to participate in regular exercise. This can range from a structured exercise class provided by a trained physiotherapist, to a daily walk around their local park.

The recommended physical activity levels for those with kidney disease are not different from those for the general population. 150 minutes of moderate intensity aerobic activity per week is recommended, in addition to muscle strengthening, balance, and flexibility activities at least twice per week. For those who are already active, guidelines recommend 75 minutes of vigorous intensity aerobic activity per week.

This can sound like a lot of activity for anyone who has a relatively sedentary lifestyle, and CKD patients also tend to have a lot of fear around exercise and injuring themselves. They are a complex patient cohort with multiple medical co-morbidities, so guidance and exercise prescription from a specialised renal physiotherapist is of the upmost importance. A behavioural approach is also crucial to assist patients to successfully adopt and maintain improved physical activity habits. Offering structured and supervised exercise programmes intended to improve patients’ knowledge and awareness of exercise in a safe and supported environment can also foster a culture of ongoing engagement in exercise, even after the programme has ended for them.

Exercise and end stage kidney disease

ESKD, culminating in the initiation of haemodialysis for many patients, is associated with an increased risk of functional impairment, a high incidence of frailty, mood disorders, and CVD. Due to the challenges in managing calcium, phosphate, and vitamin D in patients, there is also a high incidence of mineral bone disorders such as renal osteodystrophy and fractures in ESKD. High rates of sarcopaenia are also found with haemodialysis patients due to muscle catabolism, hormonal changes, low grade inflammation, and metabolic acidosis. This results in a higher risk of falls and hospital admission rates, with a higher mortality risk both during and after hospital admissions. Due to all of these reasons, chronic haemodialysis patients are amongst the highest consumers of healthcare resources. When it comes to frailty, it is a vicious cycle for haemodialysis patients if they do not engage in regular exercise as they are predisposed to sarcopaenia, and if this is a contributing factor to a hospitalisation, these tend to be lengthy hospital admissions, which in turn causes increased muscle wasting and a further decline in physical function.

Both primary and secondary prevention of CKD modifiable risk factors is vital, and exercise during haemodialysis, known as intra-dialytic exercise, plays a role in this. In many international haemodialysis centres, it is common to see patients participating in exercises, such as cycling and lifting weights, while receiving haemodialysis.

However, these intra-dialytic exercise programmes for haemodialysis patients are not routinely established in Irish healthcare, despite being endorsed by key haemodialysis guidelines, including Renal Association Haemodialysis Guidance.

An abundance of research has been conducted over the last 10-to-15 years, with all studies concluding that intra-dialytic exercise is safe, feasible, and effective in improving a patient’s functional status, exercise capacity, quality-of-life, cardiovascular health, and reducing inpatient length of stay. Research has also been conducted looking specifically at the role of exercise in haemodialysis efficacy, however, significance in these results have not been demonstrated. The best results are seen with an intra-dialytic exercise programme lasting greater than six months, a combination of aerobic exercise and progressive resistance training, and for patients also to be partaking in exercise on their non-dialysis days. Due to the complex nature of this form of exercise prescription, it is recommended that renal physiotherapists oversee the delivery of intra-dialytic exercise and complete individualised assessments on these patients.

Exercise post-kidney transplant

The optimal treatment for ESKD is kidney transplantation. Nevertheless, the exercise journey does not stop at kidney transplantation; it now moves to the next step of the medical journey – maintenance. Kidney transplant recipients still experience increased incidence of cardiovascular, metabolic, oncologic, and infectious diseases. In order to limit disease progression, improve quality-of-life, and maximise physical function, multidisciplinary renal rehabilitation, including medical nutrition therapy and regular exercise, are recommended. The level of physical activity in patients with CKD commonly decreases with disease progression, and does not fully recover after transplantation. Patients post-kidney transplantation typically report low amounts of physical activity, low energy levels, fatigue, poor exercise capacity, and a sedentary lifestyle. Multidisciplinary interventions, including exercise interventions, should be set up in Ireland to target this kidney recipient population.

Conclusion

One of the most common statements used in preventative healthcare is ‘if exercise were a pill, it would be one of the most widely prescribed and cost-effective drugs ever invented’. This is also true with CKD, and physiotherapy is a driving force in the exercise prescription that is becoming a common tool for the CKD management toolkit. It is also an exciting area to be involved in, as the renal physiotherapy journey in Ireland is only beginning. This type of exercise prescription for CKD discussed in this article is not a new concept for physiotherapists. Physiotherapists are already leading the way in exercise due to their specialised knowledge of mobility, balance, physical activity, and delivering exercise interventions. Renal physiotherapists in Ireland are integral to ensuring people living with kidney disease can access person-centred care, behavioural change, and exercise interventions to improve their physical, psychological, and emotional health. New research is emerging every year supporting various types of exercise and physical activity at all stages of kidney disease, so, the question is, what is next for the future of renal physiotherapy in Ireland?

References on request

Clíona Barrett, Senior Renal Physiotherapist, Tallaght University Hospital, Dublin