Based on the findings of the current study, the QoL of patients with schizophrenia varied considerably across the control and intervention groups. In line with this finding, Brenes et al. reported that aerobic exercise has no significant effect on the mental health domain of older adults with minor depression (
29). On the other hand, Kalateh-Jari et al. demonstrated that aerobic exercise positively influences the QoL of schizophrenia patients (
30). Gorczynski et al. argued that aerobic exercise improves the physical health of schizophrenics. Thus, it is interesting that the results of Gorczynski's study coincide with this study, considering the positive effects of physical health on the QoL of patients with schizophrenia (
31). Falkai et al. acknowledged that exercise is positively associated with mental health, anxiety, depression and negative mood, self-esteem, and cognitive function in schizophrenics (
32). Exercise can improve mental and physical health, cognitive function, and brain by increasing the volume of the hippocampus (
33-
35).
Nevertheless, factors such as type and duration of the exercises, the gender of the participants, nature of the disease, sample size, and the time interval of measuring the variables after the intervention may have caused differences. Another Challenging point is the lack of agreement on the quality of sports programs and exercises for patients with chronic lung diseases and other mental disorders. In each of these studies, a particular method has been used for instructing the exercise. In this study, aerobic exercise performed 24 sessions, three sessions per week, and ranged from 12 to 26 minutes, and QoL scores improved from 67.44 ± 18.13 to 41.91 ± 6.34 (measured by QOLS). But in the study of Kalateh-Jari et al., the patients performed 20 exercise sessions per session for 30 minutes, and the QoL score improved from 52.1 ± 14 to 67.15 ± 9 (measured by QOLS). In another study conducted by Brenes et al., exercise sessions lasted 60 minutes and consisted of both aerobic and resistance training. Each session consisted of a 5-minute warm-up, 15-minute aerobic phase, a 20-minute resistance training phase, a 15-minute aerobic phase, and 5 minutes cool-down period. The QoL scores improved from 54.1 ± 14.3 to 31.3 ± 13.5 (measure by the SF-36 mental health component). It seems the methodology used by Brenes to perform sports exercises to improve the QoL of patients with chronic schizophrenia is more appropriate than other studies because it is more regular and uses both aerobic and resistance exercises.
What is more, the findings revealed is a significant difference in terms of the motivation dimension of QoL in both groups after the intervention. All points are taken into consideration; the regular aerobic exercise can enhance the motivation of participants.
Among psychological factors, personal motivation plays a fundamental role in ameliorating lifestyle programs and modifying unhealthy habits. Researchers emphasize increasing motivation in schizophrenia, which means enjoying QOL. Because motivation can change a person from a static state to a dynamic state by changing interpersonal factors. Thus, motivation may be considered as an interpersonal accessible factor that can be modified during a change process (
36).
On the other hand, this study showed that exercise regulates neurotransmitters such as dopamine, serotonin, glutamate, norepinephrine, and acetylcholine, which are related to the biological etiology of schizophrenia (
37).
The current study had limitations, including only investigating male patients. Therefore, the results cannot be generalized to female patients. Further studies with a special focus on women are needed. Moreover, it should be noted that the psychosocial status of respondents during questionnaire completion and exercise can affect the quality of their responsiveness and performance.
In conclusion, although mental disorders, such as schizophrenia, negatively affect the QoL of patients, but they can improve their QoL through regular aerobic exercise. Also, exercise can enhance the QoL domains, such as the psychological, motivation and energy, and symptoms and side effects of patients with schizophrenia. To recap, it is recommended to provide various training programs such as consulting, physical, and psychological protection to patients and their caregivers.