Physical Activity Accumulation in Bouts and Nonbouts and Relation to Cardiorespiratory Fitness in Older Adults

PURPOSE:Regular moderate-to-vigorous physical activity increases life expectancy if accumulated in bouts of at least 10 minutes each (MVPA10) (ACSM, 2013). However, nearly half of older adults did not comply with this prescription (Davis, 2007). Leisure time physical activity (PA), in healthy adults across a broad age range, seems to be a relatively minor independent contributor to aerobic capacity (Talbot, 2000) but in this study differences between overall moderate-tovigorous PA (MVPA) and MVPA10 were not considered. Therefore, the aim of this study was to compare the effects of physical activity performed in bouts (≥10 minutes) to the effects of physical activity spent in nonbouts (<10 minutes) on cardiorespiratory fitness (V'O2max) of a set of older adults. METHODS:In 12 older adults (age: 69.4±4.3 yy; weight: 78.5±10.5 kg; height: 171.2±5.3 cm; BMI: 22.9±2.7 kg/m2; V'O2max: 29.5±4.1mL/kg/min) physical activity was assessed for 6 consecutive days using a portable multisensor monitor. Data were evaluated in 60s epochs providing total time spent performing MVPA and MVPA10 (3 METS were used as the cutoff for MVPA). V'O2max was measured by indirect calorimetry during a two-step cycling test. The first one consisted in a ramp test with continuous workload increment (10-20 W/min) until exhaustion. Then, after five minutes of recovery at 30 W, the subject resumed pedaling against a constant-load equal to 105 % of the mechanical power achieved at the end of the ramp test (Rossiter, 2006). RESULTS:Although both MVPA and MVPA10 significantly exceeded (p<0.05) PA guidelines for older adults, MVPA was significantly (p