Cardiovascular Risk in Sedentary Elderly During Prolonged Sitting Time Versus Intermittent Sitting Time

In adults, the sedentary behavior was related to cardiovascular risk markers, regardless of the level of physical activity (PA). However, the interruption of prolonged sedentary time has shown positive results even when performed in breaks of low intensity and short duration of activity. The aim of this study is to analyze the influence of a sedentary uninterrupted period, as well as different forms of breaks in sedentary time for the glycemic, insulin and inflammatory markers responses in older adults. This is a controlled clinical trial to be conducted in older (≥ 65 years) and sedentary (\<150 min / week of moderate to vigorous physical activity) people. Those with BMI ≥ to 35.00 kg /m2; diabetic, on medication for glycemic control, or with absolute or relative contraindications to PA practice will not be included . Participants will undergo four phases of intervention separated by an interval of 7 days: (1) Prolonged Sitting Time(PST), in which older people will stay for 5 hours seated; (2) Prolonged sitting with PA of light intensity and short duration (LiSd), time sitting is interrupted for PA bouts of 50-60% of the Heart Rate (HR)max; (3) Prolonged sitting with PA of moderate intensity and short duration (MiSd), time sitting will be interrupted for PA bouts of 65-75% predicted HR max; (4) Prolonged sitting with PA of moderate intensity and long duration (MiLd,) time sitting will be interrupted with PA bouts of 65-75% of HRmax. PA bouts will be performed by walking into a hallway every 20 minutes of sitting time and will last 2 minutes, except in MiLd phase (10 minute breaks every 75 minutes). To evaluate the effects of different PA interruptions in plasma glucose, serum insulin and inflammatory markers, blood samples will be collected serially (-30min, Baseline and 30min, 1h, 2h, 3h, 4h and 5h after a standardized meal. It is expect that interruption of sedentary time, even with breaks of short duration and light intensity can bring benefits to cardiovascular