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Physical Activity for Health: What Kind? How Much? How Intense?

Abstract

• Regular physical activity is linked to improved health outcomes.

• Different intensities and types of activity yield various benefits.

• Health risks decrease as physical activity increases, with most benefits seen at low levels.

• Light-intensity activity reduces health risks more than a sedentary lifestyle.

• Gradually increasing activity in small increments is recommended to minimize risks and enhance compliance.

• There is a proposal to shift from considering moderate activity as the baseline to a zero-activity starting point for health studies.

Introduction

• Growing evidence supports that physical activity offers numerous health advantages.

• Questions remain about the type, intensity, and amount needed for optimal benefits.

• The U.S. Department of Health and Human Services issued physical activity guidelines (2008) to inform activity levels for health benefits.

• The recommendation is:

  • 150–300 minutes per week of moderate-intensity aerobic activity or 75 minutes of vigorous-intensity activity.

  • A mix of both types is acceptable, with one minute of vigorous activity equating to two of moderate.

  • Benefits increase with more activity beyond these limits.

• The article will discuss key components of physical activity and health:

  1. Physical activity, physiology, and health

  2. Volume, dose-response, and intensity

  3. Safely increasing volume

  4. Starting from zero.

Physical Activity, Physiology, and Health

• Regular physical activity is essential for reducing the risk of chronic diseases.

• Listed health benefits: reduced risks for:

  • Early death

  • Coronary heart disease

  • Stroke

  • Hypertension

  • Type 2 diabetes

  • Certain cancers (e.g. breast, colon)

  • Depression and cognitive decline.

• Various activities lead to distinct physiological changes:

  • Aerobic activities enhance cardiovascular function and efficiency.

  • Anaerobic activities focus on strength and power, impacting skeletal muscle and energy systems.

  • All forms of activity contribute to overall health and functional improvement.

• Important terms:

  1. Aerobic Activities: involve large muscle groups over time (e.g. walking, dancing).

  2. Anaerobic Activities: short bursts of high-intensity efforts (e.g. sprinting).

  3. Cardiorespiratory Fitness: indicates the ability of the body to supply oxygen during sustained activity.

  4. Functional Ability: capacity to perform daily tasks.

  5. Physical Activity: any skeletal muscle movement that expends energy.

Volume, Dose-Response, and Intensity

• Understanding how much activity is needed is crucial for health benefits.

• Components of activity volume:

  1. Duration (length of the activity session)

  2. Frequency (how often it occurs)

  3. Intensity (effort level).

• Higher volume usually correlates with greater health outcomes, without a defined upper threshold for benefits.

• Research indicates no lower threshold for activity benefits; any increase in activity yields health gains.

• Dose-response relationships show risk reduction correlating with increased activity levels.

• Important terms regarding volume and intensity:

  1. Accumulation: short activity bursts throughout the day combined to meet guidelines.

  2. Intensity: Absolute and Relative: absolute concerns energy expenditure; relative gauges effort compared to individual capacity.

  3. METs: a way to express physical activity level (1 MET = resting state).

Safely Increasing Volume of Physical Activity

• Risks associated with increasing activity levels include:

  • Musculoskeletal injuries

  • Cardiac incidents while exercising.

• Emphasizing gradual increases is key to avoiding injuries:

  • Principles of overload and progression should guide activity increases.

  • New participants should ideally begin with light to moderate activities to adapt safely (e.g. start with short duration walks).

• Health benefits generally overshadow risks of starting an exercise regimen.

Starting From Zero

• A conceptual shift is suggested, focusing research on the health effects of low-intensity activities and advocating for starting physical activity from a zero baseline rather than a low baseline.

• Research advances enable better measurements of all activity intensities, indicating beneficial effects even from light actions like standing or walking slowly.

• It is essential to recognize the value of overall daily activity, not just structured exercise, enhancing public health interventions.

Summary and Discussion

• The volume of physical activity has decreased in the population despite its known health benefits.

• Higher intensities were the initial focus of health benefits, but recent knowledge extends the conversation to include light-intensity activities.

• Public health messages should focus on:

  • The importance of all types of activities, not just vigorous exercise.

  • The recommendation to engage in light activities to combat the health effects of sedentarism.

• Future research should further explore how various intensities, volumes, and types of activities interrelate to optimize health outcomes.