The human body is a complex system of muscles, joints, bones, and organs designed to thrive with movement. Throughout history, humans have had to walk, run, lift, climb, and carry to survive, and our physiology evolved to support these activities. Today, however, modern lifestyles often involve long periods of sitting or standing still, which goes against our bodies’ natural design and can have detrimental effects on our health. Science shows that lack of movement affects everything from our metabolism to mental health, and simply put, our bodies were made to move.

This article explores the science behind why human bodies require movement and how our sedentary habits are affecting our well-being.

1. Evolutionary Biology: The History of Human Movement

Human beings are descendants of hunter-gatherers who relied on mobility for survival. Our ancestors had to walk long distances, sprint to avoid predators, climb, and carry food or water. Over thousands of years, our bodies adapted to support this active lifestyle:

• Endurance: Humans are uniquely adapted for endurance activities, like long-distance running and walking. Our long legs, arched feet, and sweat glands all evolved to support sustained movement.
• Joint Mobility and Stability: Humans have flexible shoulder joints, enabling us to throw objects, climb, and carry items over long distances. Additionally, we have large gluteal muscles to support walking and running, and our hip structure is optimized for movement.

These evolutionary adaptations indicate that our bodies are meant to be in motion. Sedentary behavior, by contrast, deprives the body of the stimulation it evolved to expect, leading to a host of negative health consequences.

2. The Science of Muscle and Bone Health: Movement for Strength and Density

Movement is crucial for maintaining muscle strength and bone density, both of which are essential for long-term health and injury prevention.

Muscle Atrophy from Inactivity

Muscles are designed to contract and stretch regularly. When we don’t move, muscles become weak and atrophy. Studies have shown that:

• Muscle Loss: Just two weeks of inactivity can lead to a measurable reduction in muscle mass, particularly in the legs and core, which support posture and balance.
• Strength Decline: Strength declines rapidly with inactivity. Research shows that people can lose as much as 30% of their muscle strength after three weeks of bed rest or inactivity.

Bone Density Reduction from Sedentary Behavior

Bones also require regular weight-bearing activities, like walking, running, and lifting, to remain strong:

• Osteoporosis Risk: When bones aren’t subjected to the mechanical stress that comes with movement, they lose density, becoming more brittle and susceptible to fractures. A sedentary lifestyle increases the risk of osteoporosis, a condition in which bones lose density and become fragile.
• Wolff’s Law: Wolff’s Law states that bone grows in response to the forces placed upon it. Lack of movement reduces these forces, leading to weaker bones over time.

3. Circulatory Health: Movement Supports Blood Flow

Circulation is vital for delivering oxygen and nutrients to tissues and removing waste products. Movement promotes circulation by engaging muscles, which helps pump blood throughout the body:

• Reduced Circulation While Sitting: When we sit for extended periods, circulation slows down, particularly in the lower extremities. This can lead to blood pooling in the legs, which increases the risk of blood clots and deep vein thrombosis (DVT).
• Benefits of Muscle Contractions: When muscles contract during movement, they squeeze blood vessels, pushing blood back to the heart and promoting circulation. Walking and other forms of light movement can help lower blood pressure and reduce the risk of cardiovascular diseases.

A study published in the American Journal of Physiology found that just a few minutes of walking can counteract the harmful effects of sitting on blood flow, highlighting the importance of frequent movement for cardiovascular health.

4. Metabolic Health: Movement for Energy Balance and Weight Control

Movement is also essential for metabolic health, as it helps regulate blood sugar levels, supports energy balance, and promotes a healthy weight.

• Insulin Sensitivity: Physical activity increases insulin sensitivity, which helps cells absorb glucose from the blood for energy. Inactivity reduces insulin sensitivity, raising the risk of insulin resistance and type 2 diabetes. Research shows that a single day of prolonged sitting can reduce insulin sensitivity by 39%, highlighting how essential movement is for metabolic health.
• Caloric Burn: When we move, we burn calories, helping to prevent excess weight gain. Sedentary behavior lowers calorie expenditure, making it easier to gain weight and harder to lose it.

A study from Diabetologia found that prolonged sitting is directly associated with increased insulin levels and higher blood glucose, both risk factors for diabetes. Regular movement, even short bursts throughout the day, is essential for preventing these metabolic issues.

5. Mental Health: Movement for Brain Function and Mood

Movement is not only beneficial for physical health; it also supports mental well-being and cognitive function.

• Endorphin Release: Physical activity stimulates the release of endorphins, often called “feel-good” hormones. These hormones reduce stress, improve mood, and can even alleviate symptoms of anxiety and depression.
• Cognitive Function and Memory: Exercise increases blood flow to the brain, promoting the growth of new brain cells and supporting cognitive functions like memory and learning. Studies have shown that even a 10-minute walk can improve memory and cognitive function, underscoring the importance of regular movement for brain health.
• Reduced Cortisol: Movement helps regulate cortisol, the body’s stress hormone. Chronic stress increases cortisol levels, which can lead to inflammation and immune suppression, both of which hinder healing and increase disease risk.

6. Flexibility, Mobility, and Joint Health: Movement Keeps Joints Healthy

Joints require movement to stay flexible and lubricated. Lack of movement contributes to stiffness, reduced range of motion, and joint pain.

• Synovial Fluid Production: Movement stimulates the production of synovial fluid, which lubricates joints and reduces friction between bones. When joints remain immobile, synovial fluid decreases, leading to stiffness and discomfort.
• Preventing Arthritis: Regular movement helps reduce the risk of developing arthritis. Studies show that sedentary people have a higher risk of joint degeneration and conditions like osteoarthritis.

A study from the Journal of Orthopaedic Research found that regular movement, particularly low-impact activities like walking or swimming, can reduce joint inflammation and support long-term joint health.

7. The Impact of Sedentary Lifestyles and “Sitting Disease”

Modern sedentary lifestyles, characterized by long hours of sitting at desks, watching screens, or commuting, pose a significant threat to health. The term “sitting disease” has even been coined to describe the health risks associated with prolonged sitting. Research shows that excessive sitting is linked to higher risks of:

• Heart Disease: Studies show that sitting for extended periods can increase the risk of cardiovascular diseases, as inactivity leads to increased blood pressure, higher cholesterol levels, and inflammation.
• Diabetes and Obesity: Sedentary behavior is a major risk factor for obesity and type 2 diabetes. Even among people who exercise regularly, prolonged sitting periods can negate many of the benefits of physical activity.
• Shortened Lifespan: A meta-analysis in The Lancet found that prolonged sitting is associated with an increased risk of early death, even in people who meet physical activity recommendations.

8. Incorporating More Movement into Daily Life

Even small amounts of movement throughout the day can have substantial health benefits. Here are a few ways to make movement part of your daily routine:

• Take Frequent Breaks: Stand up, stretch, or take a short walk every 30 minutes.
• Use a Standing Desk: Alternate between sitting and standing while working.
• Incorporate Walking into Daily Tasks: Walk during phone calls or consider “walking meetings.”
• Exercise Regularly: Aim for at least 150 minutes of moderate-intensity activity each week, as recommended by health guidelines.

Conclusion

Human bodies were not made to stand still; they were designed for movement. Evolutionary history, muscle and bone health, circulation, metabolism, mental well-being, and joint health all underscore the importance of regular physical activity. Our sedentary lifestyles today conflict with the natural design of our bodies, leading to a range of health issues. By prioritizing movement and avoiding prolonged periods of inactivity, we can support our bodies’ needs and promote long-term health.

Remember, movement doesn’t need to be intense; even gentle, consistent activity can make a difference in your daily circulation, energy levels, and overall well-being.