According to the United States Renal Data System (2015), in 2013, 88.2% of all incident cases of ESRD involved renal replacement therapy with haemodialysis, ESRD is highly prevalent in Taiwan, with 2,902 cases per million people; 89.7% of cases in 2012 involved maintenance haemodialysis treatment as the renal replacement therapy. Patients generally receive haemodialysis 3 days per week, and each session generally takes 4 hr. Beginning dialysis induces multiple physical and psychological stressors in patients. In particular, the importance of intervention programs improving psychosocial function should be noted considering disease and its long-term treatment. High depression and fatigue are crucial for consideration in the global care of dialysis patients because these factors are associated with mortality. A significant correlation exists between reduced physical activity and increased depression or fatigue; with decreased activity, muscle strength decreases, which exacerbates depression and fatigue.

Depression is the most common psychosocial problem observed in ESRD patients undergoing haemodialysis, with a prevalence between 27.9% and 40.2% associated with a high risk of hospitalisation and prolonged hospital stay, reduced quality of life (QOL), decreased adherence to dialysis prescriptions, and increased medical comorbidity.

Fatigue is another critical concern caused by haemodialysis; ESRD patients receiving haemodialysis have reduced red blood cell production, thus causing fatigue, the prevalence of which ranges between 53% and 97%. Fatigue has a negative effect on the physical function, ability to perform daily activities, QOL, and even survival of patients. QOL is the subjective perception of an illness and corresponding treatment regarding physical, psychological, and social well-being; however, QOL serves as a prognostic measure and predictor of survival. ESRD patients receiving haemodialysis have a lower QOL than do other patients with other chronic illnesses and general population. Lower health-related QOL is associated with higher rates of hospitalisation and lower rates of survival among patients undergoing haemodialysis. Therefore, identifying effective interventions to assist ESRD patients receiving haemodialysis in managing their physical, psychological, and social problems is critical.

Regular exercise could improve general health in many chronically ill patients. Planned exercise programs are nonpharmacological interventions that can safely and effectively improve depression, fatigue, and QOL. For ESRD patients undergoing haemodialysis, many previous studies have shown that exercise decreases fatigue and depression, and improves QOL. Accordingly, an intradialytic exercise program should be considered as a possible therapeutic approach for improving fatigue, depression, and QOL in ESRD populations and should be encouraged by and performed in haemodialysis centres. Although the benefits of related exercise programs are known, an effective intradialytic exercise program for routine therapy has not yet been developed. Few previous studies have implemented exercise programs to examine the effects of psychological factors and QOL on patients receiving haemodialysis in Taiwan.

Exercise self-efficacy is a crucial mediator of health behaviour. Self-efficacy is a key construct in social-cognitive theory, in which personal beliefs correspond to an individual's perceived ability to successfully perform specific tasks and activities. Pertaining to beliefs in a person's ability to manage prospective situations, self-efficacy beliefs focus on mediating change in individual behaviours. Thus, self-efficacy has a mediating effect on depression resulting from stressful events. Self-efficacy as a mediator complements family and healthcare provider support in diminishing the negative impact of depression in haemodialysis patients. Relevantly, resilient people tend to have apparent adaptive behaviours, particularly those related to somatic health. Resilience specifically refers to smooth and rapid recovery from setbacks that may occur in a person's life. As such, psychological resilience is considered a protective mechanism that operates in the presence of negative stressors. People who are maladaptive with low competence and low adversity score lower on these measures than resilient and competent groups do. Exercise self-efficacy, resilience, and exercise behaviour are interrelated. Self-efficacy may motivate people to perform their physical activity. However, the true effect of exercise programs fails to account for the mediating effects of exercise self-efficacy and resilience.

Purpose Statements The purpose of this study was to investigate the effect of an intradialytic aerobic and resistance cycling exercise program (IARCEP) on depression, fatigue, and QOL in ESRD patients receiving haemodialysis, and to further determine the effect of mediation through exercise self-efficacy and resilience in patients receiving the IARCEP.

METHODS Research Design and Participants This study adopted a randomised controlled trial design. ESRD participants were recruited from a haemodialysis centre in an 872-bed regional hospital in Northern Taiwan. Data were collected over a 14 months in 2013-2014. The exercise group received routine nursing care in addition to the IARCEP for 3 months. The control group received only routine care in the same study period. A randomisation procedure was performed outside of the study site by two nurse researchers. Permuted-block randomisation, for which every block comprised four patients, was adopted to balance the number of patients in the exercise and control groups. A randomisation list was drawn using random computer-generated sequences. Information regarding these sequences was separately placed in opaque, sealed envelopes to ensure that the participants were randomly allocated to the exercise or control group. Outcomes were repeatedly measured four times at baseline and the first, second, and third months.

Intradialytic aerobic and resistance cycling exercise program (IARCEP) An exercise program brochure for the IARCEP was made available to the exercise group participants to ensure that stationary cycling would be performed appropriately. A horizontal electromagnetic cycle ergometer (Medical Exercise Peddler 3000, Medi-Bike, Taiwan) was used for the participants' cycling performance. The exercise was performed during the first 2 hr of each haemodialysis session (30 min per session, 3 sessions per week for 3 months). All participants were assessed for cardiac and other medical contraindications to exercise by using PAR-Q. Participants were required to perform stationary cycling at an intensity of 11-13 out of 20, corresponding to the rate of perceived exertion on the Borg scale, whereby the intensity was 65%-85% of the participant's maximal capacity, representing the level at which cardiovascular health can be maintained. Exercise was paused when the participants had systolic blood pressure over 180 mmHg, diastolic blood pressure over 95 mmHg, heartbeat under 60 beats/min, or pulse oxyhaemoglobin saturation (SpO2) under 88%. The participants' cardiac rhythm was continuously monitored. Blood pressure and SpO2 was also measured every 5 min. The criteria for interrupting exercise included physical exhaustion, chest pain, dyspnoea, dizziness, and significant instabilities in heartbeat or blood pressure. Immediately following exercise, the participants were assisted with removing the stationary cycling gear to adopt a comfortable position for the immediate assessment of blood pressure, heart rate, and SpO2. Participants were included in the subsequent analysis if they performed the aforementioned exercise procedure at least 10 times per month.