Obstructive sleep apnea (OSA) is a disorder that exposes the individual to repeated periods of hypoxia and awakenings during sleep. OSA occurs in up to one third of the population, constituting a public health problem. The prevalence of sleep apnea increases with age, reaching up to 90%. Its consequences include sympathetic nervous system activation, increased blood pressure and heart rate, myocardial contractility overload, decline in parasympathetic activity, oxidative stress, systemic inflammation, platelet activation, and impaired vascular endothelial function. OSA is a risk factor for hypertension, coronary artery disease, peripheral artery disease, heart failure, and arrhythmias. The classical treatment options for OSA are the use of continuous positive airway pressure, oral appliances for mandibular advancement, surgery, weight reduction, and lifestyle change, including recommendation of regular practice of exercise.

Physical exercise is accepted culturally and scientifically as a non-pharmacological intervention beneficial to health. Aerobic and resistance exercises improve the quality of sleep. There is evidence of improvement in the general well-being and, particularly in sleep. Promote or improve sleep through exercise is healthy, safe, and simple. A sedentary lifestyle is linked with a higher incidence and severity of sleep apnea. Increase in the number of hours of exercise reduces these problems. Exercise has been used with consistent results to treat OSA. The effect size of exercise in treatment of OSA ranges between 0.4 and 1.5 standard deviations. In a meta-analysis, totaling 129 participants, the mean effect was the reduction of 7 events per hour. Although the results of randomized clinical trials and other studies pointing to the decrease in AHI after physical training, all studies involved adult populations with an average age between 42 and 54 years. The role of exercise in the elderly with OSA, the most affected population, remains uninvestigated.

The research question is: What is the effect of strength training on the apnea-hypopnea index (AHI) in elderly with OSA? The objective of the study is to evaluate the impact of strength training on OSA in the elderly.

The trial will recruit individuals aged 65 to 80 years ascribed to a primary care unit linked to the university hospital. Individuals that accept to participate in the study, will undergo out-of-center polysomnography in order to detect and quantify the severity of OSA. Individuals with AHI between 20 and 50 events per hour will be eligible, and will be randomly allocated to the intervention or the control group. Randomization will be performed by sequence numbers generated by computer at randomization.com.

Individuals allocated to the intervention group will hold two sessions per week of strength training consisted of exercises for legs, arms, chest, back, and abdomen in the university Physical Education High School, during 12 weeks. The individuals allocated to the control group will receive advice on lifestyle and will participate in the meetings of an elderly social group in the basic health unit. All individuals from both groups will perform an evaluation consisting of body composition by bioelectrical impedance, maximum dynamic force by 1-repetition maximum strength test, quality and muscle thickness by ultrasound, and physical function by Sit-to-stand test, Timed up and go test and Handgrip strength test. All evaluations will be repeated at the end of the 12-week period.