Chapter 2: The health consequences of physical inactivity and sedentary behavior

Intro #1

Technological advances over the last century have reduced the need for human movement throughout the day

Intro #2

Lower levels of movement are needed to complete activities of daily living (ADLs)

Intro #3

Less individuals participate in active transport ( walking, cycling, etc)

Intro #4

Less than 20% of jobs require moderate-intensity activity

Intro #5

These societal changes have lead to increased obesity, CVD, diabetes, certain cancers and many other comorbidities

Inactivity

Individuals or groups of individuals not meeting a certain threshold of moderate to vigorous activity

Standard adult aerobic recommendations

moderate intensity more or equal to 30 minutes per day on more than or equal to 5 days er week for a total of more than or equal to 160 min per week, Vigorous intensity: more or equal to 20 minutes per day on more than or equal to 3 days per week of total of more than or equal to 75 min per week

recommendations for inactivity

Resistance training, neuromotor and flexibility exercises are also recommended

standard child/adolescent aerobic recommendation

60 minutes or more of moderate to vigorous intensity activity

Deconditioning

reduction or cessation in exercise and increases in physical inactivity that results in partial or complete reversal of physiological adaptations to activity, common causes: reduced physical activity, bed rest, casting, paralysis and aging

Detraining

process by which adaptions to exercise are gradually lost or reduced: specific to exercise, thus it is the form of deconditioning most relatable to inactivity, linked to numerous comorbidities and poor health outcomes

Prevalence of inactivity

self-reported survey data suggest 45%-75% of US adults are physically inactive, Accelerometer data suggest: 58% of youth(6-11yr) are physically inactive, 90% of adolescents (12-19yr) are physically inactive, 95% of adults (>20 yr0 are physically inactive

Exercise is medicine

A global initiative to decrease population levels of inactivity, primary stakeholders include the following: health care providers, exercise professionals, and community resources

exercise is medicine stakeholders

healthcare providers, exercise professionals, community resources

Sedentary behavior

walking behaviors that take place while in a sitting or reclined position and result in an energy expenditure of less than or equal to 1.5 METS. Can be assessed with surbey data, accelerometers and or inclinometers

Sedentary physiology

study of the body’s responses to short-term and long0term sedentary behavior (focus on identifying mechanism that are distinct from the biological basis of exercising). Sedentary behavior and exercise can be viewed as regions along a continuous scale of MET values (known as the movement continuum)

Sedentary behavior and overall mortality

numerous studies have displayed a link between sedentary behavior and mortality( meta-analysis of 18 studies determined sedentary behavior was associated with a 49$ increase in all-cause mortality)

sedentary behavior and cardiovascular disease

recent meta-analyses have shown the link between screen time and CVD(one suggested that CVD risk increased by 17% with each 2-hour increase in screen time per day

Sedentary behavior and obesity

long term weight gain associated with obesity occurs when caloric food intake exceeds total energy expenditure (TEE). Activity thermogenesis can be divided into exercise activity thermogenesis (EAT) and non-exercise activity thermogenesis (NEAT). NEAT includes active transport, work related activity, non-exercise leisure activity and or ADLs. Benefits to TEE can be achieved by converting sedentary time to activity time, including both NEAT and EAT

sedentary behavior and diabetes/metabolic disease

sedentary behavior is linked to lipoprotein lipase (LPL) activity in skeletal muscle, which can lead to higher plasma glucose levels

Other sedentary behavior health effects

there has been a strong link to an increased risk of developing cancer, decreased bone mineral density and or decreased physical function in older adults

sedentary behavior goals and guidelines

sedentary behavior reduction should be seen as a complement to without becoming a replacement for setting exercise goals

Reductions in sedentary behavior may be a more accomplishable proximal goal

Especially for individuals not meeting prescribed levels of physical activity

No standardized protocols for reducing sedentary behavior exist

some organizations and national government have adopted general guidelines related to sedentary behavior