Physical inactivity and a sedentary lifestyle are prevalent in the population with intellectual and developmental disabilities, and they do not comply with the World Health Organisation's physical activity guidelines. Due to physical inactivity and a sedentary lifestyle, these individuals have low levels of physical fitness (decreasing functional capacity and success in carrying out activities of daily living), with an increased risk of acquiring other comorbidities such as type II diabetes, hypertension, cholesterol and metabolic syndrome, affecting their quality of life.

One of the reasons found in the literature for physical inactivity and sedentary lifestyles in individuals with intellectual and developmental disabilities is the existence of barriers that prevent/difficulty their practice, namely the lack of adapted physical exercise programmes, limited financial resources and lack of venues for their practice. Consequently, there is a dearth of research, including little clarity on the intervention protocols used and a variety of methodologies that address the applicability of non-pharmacological, psychological and psychosocial interventions, such as physical exercise programmes, for the promotion of various variables.

One of the most studied relationships is between exercise and the promotion of physical fitness, confirming its direct impact on functional capacity. Bearing in mind that studies on cognitive decline only assess some variables that may be associated but do not represent it on their own, such as attention, memory and language fluency. With regard to quality of life, an 8-week multidisciplinary exercise intervention programme aimed to improve quality of life, professional and peer support for activity, abdominal strength and metabolic equivalent gait of the tasks, however, the physical exercise programme is unclear and multimodal. On the other hand, a previous systematic review associated the effects of physical exercise with variables related to quality of life, namely pain, general health and anxiety. In studies focusing on physical activity, these variables have been shown to be predictors of quality of life, however, studies with physical exercise programmes are still cautious or unclear.

Thus, alternative and innovative solutions to promote/maintain physical function, reduce the risk of onset of cognitive decline in early life and promote/maintain the quality of life of individuals with Intellectual and Developmental Difficulty should include physical exercise. Taking this introductory approach into account, this non-randomised experimental study aimed to analyse the effects of two 24-week physical exercise programmes (indoor and outdoor) on functional capacity, cognitive decline and quality of life in institutionalised individuals with intellectual and developmental disabilities.

Adult institutionalized volunteers from Leiria region (Center Portugal) participated in the exercise intervention program.

Participants were selected using the following inclusion criteria:

• adults with IDD;
• without medical contraindications;
• age over 18 years;
• with mild, moderate or severe IDD diagnosis (Down Syndrome inclusive);
• success in performing movements such as pulling/pushing;
• ability to carry out the intended assessments.

Additionally, we also used the following exclusion criteria:

• individuals who cannot commit for 6 months;
• individuals with other associated pathologies;
• contraindications to PE;
• inability to walk unassisted;
• profound IDD;
• inability to communicate;
• non-delivery of the duly signed informed consent.