The Hidden Cost of "Just Sitting Down More"

"I' find I tend to sit around a lot more these days"

As a physiotherapist, it's a phrase I hear regularly. Usually, it comes from someone who has noticed they're not quite as strong, steady or confident as they used to be. Often there hasn't been a major injury, illness or life-changing event. Instead, the change has happened gradually. A daily walk becomes less frequent. The stairs are avoided when possible. Gardening gets left until another day. Shopping is delivered instead of collected. Time spent sitting slowly increases while time spent moving slowly decreases.

COVID-19 provided the perfect conditions for deconditioning. People who had previously been active suddenly found themselves spending far more time at home, sitting more and moving less. For some, there was also a genuine fear of going out, mixing with others or returning to previous activities. Years later, I still meet patients who trace the start of their decline in mobility, fitness or confidence back to the lockdown period. What began as a temporary reduction in activity became a long-term habit, highlighting just how quickly the body can adapt to inactivity—and how important it is to keep moving whenever possible.

The problem is that our bodies are incredibly adaptable. That sounds positive, and often it is. When we exercise, challenge ourselves and remain active, our muscles, heart, lungs and balance systems adapt by becoming stronger and more efficient. Unfortunately, the opposite is also true. When we move less, our bodies adapt to moving less. This process is known as deconditioning, and it can affect almost every system in the body.

Many people assume weakness, poor balance and reduced fitness are simply part of getting older. While ageing does play a role, what I often see in practice is not ageing itself but the consequences of inactivity. The encouraging news is that deconditioning is often preventable and, in many cases, reversible.

What Exactly Is Deconditioning?

Deconditioning is the gradual loss of strength, fitness, balance and physical function that occurs when we stop asking the body to do the things it was designed to do. It is one of the most common problems I see in community physiotherapy and often develops so slowly that people

don't realise it is happening.

Unlike an injury, where there is a clear event that causes symptoms, deconditioning tends to creep up over weeks, months or even years. Many people only notice it when they suddenly struggle to do something that used to be easy, such as getting out of a chair, climbing stairs or walking to the local shop.

How Quickly Can We Lose Strength?

One of the most surprising things about deconditioning is how quickly it can occur. Research has shown that measurable muscle loss can begin within just a few days of inactivity. Studies examining bed rest in older adults found significant reductions in muscle mass and strength after only ten days, particularly in the large muscles of the thighs that are essential for standing, walking and climbing stairs.^1 Other research has demonstrated substantial muscle wasting after just one week of bed rest, alongside changes in metabolism and reductions in physical function.^2

This is particularly important because the muscles of the legs are among the first to be affected.

Every time we stand up, walk across a room, climb a step or get out of a chair, the muscles in our hips, thighs and calves are working against gravity. When we spend more time sitting, these muscles simply do not receive the same stimulus. The quadriceps muscles at the front of the thighs, the gluteal muscles around the hips and the calf muscles all begin to weaken. These are exactly the muscles we rely on for mobility, independence and balance.

The Vicious Cycle of Weakness

The result is often a vicious cycle. Less movement leads to weaker muscles. Weaker muscles make movement more difficult and tiring. As movement becomes harder, activity levels reduce further. Over time, getting out of a chair becomes more effort, walking longer distances feels daunting and stairs become increasingly challenging. Many people begin avoiding activities they previously enjoyed, not because they want to, but because they no longer feel physically capable.

As physiotherapists, we often find ourselves treating this cycle rather than a specific injury. The challenge is helping people regain enough strength and confidence to start moving more again, because movement is ultimately what breaks the cycle.

Core Strength: The Forgotten Foundation

What is often overlooked is the effect inactivity has on the body's core muscles. When people hear the word "core", they often think about gym exercises or six-pack abs. In reality, the core is much more important than appearance. It consists of the muscles around the trunk, abdomen, back, diaphragm and pelvis that provide stability and support for virtually every movement we make.

A strong core acts as a stable platform from which the arms and legs can work effectively. When activity levels reduce, core strength and endurance often decline too. This can contribute to poor posture, reduced balance, increased back pain and a feeling of instability when walking. Many people focus on strengthening their legs but forget that the trunk is what allows those legs to work effectively.

Hannah Trebilcock, Physiotherapist with Physio@Home, is Pilates trained and incorporates Pilates-based principles into her rehabilitation programmes. By focusing on core strength, posture, balance, movement control and body awareness, Hannah helps patients build confidence, improve function and move more efficiently in everyday life.

Why Balance Starts to Decline

As physiotherapists, we know that balance is not simply about the feet. Good balance relies on strength, coordination, sensation, vision and confidence all working together. When strength reduces, balance often deteriorates alongside it. Reaction times become slower. Stepping responses become less effective. The body becomes less able to recover from trips, slips and unexpected movements.

This is one reason why deconditioning is so closely linked to falls risk. Research consistently demonstrates that exercise programmes targeting strength and balance can significantly reduce falls in older adults living in the community.^3 The stronger and more active we remain, the more reserves we have when life inevitably throws us an unexpected wobble.

The Confidence Problem

Confidence also plays a huge role. One of the most common things I hear from patients is, "I'm worried I'll fall." As strength and fitness decline, people naturally become more cautious. They may avoid going out alone, stop walking as far as they once did, or rely more heavily on furniture and walking aids indoors.

Unfortunately, this reduction in activity often accelerates the very problem they are trying to avoid. Less movement leads to further weakness, which then reduces confidence even more. Breaking this cycle is often one of the most important aspects of physiotherapy rehabilitation. Sometimes the biggest barrier is not the body itself, but the fear that the body can no longer do what it once could.

Your Heart Needs Exercise Too

The effects of inactivity are not limited to muscles and balance. The heart is also affected. The heart is essentially a specialised muscle whose job is to pump blood efficiently around the body. Like other muscles, it responds to the demands placed upon it. Regular activity strengthens the cardiovascular system and improves fitness.

When activity levels reduce significantly, cardiovascular fitness declines. Research into prolonged bed rest has shown reductions in aerobic capacity, exercise tolerance and cardiovascular performance.^4 This means that activities such as walking uphill, carrying shopping or climbing stairs may leave a person feeling much more breathless than before. People often describe this as "losing their fitness" and physiologically that is exactly what is happening.

What Happens to the Lungs?

The lungs are affected too. Movement encourages deeper breathing and helps expand the lungs fully. During prolonged periods of sitting or lying, breathing often becomes shallower. This reduces lung expansion and can increase the risk of respiratory complications, particularly following illness or surgery.

Physiotherapists working in hospitals have long recognised the importance of early mobilisation because simply getting people moving again helps reduce the risk of chest infections and improves overall recovery.^5 Sometimes one of the best breathing exercises available is simply getting up and walking.

Why Physiotherapists Worry About Bed Rest

Perhaps nowhere are the consequences of inactivity more obvious than during prolonged bed rest. Modern healthcare has largely moved away from prescribing extended periods in bed because we now understand the significant risks involved. Bed rest can accelerate muscle wastage, reduce cardiovascular fitness, impair balance, increase the risk of pressure sores, contribute to constipation, increase the likelihood of chest infections and raise the risk of blood clots.^5

A hospital admission that requires several days in bed can result in a noticeable loss of strength and independence, particularly in older adults. This is why hospital physiotherapists often seem so keen to get patients out of bed and moving as soon as it is medically safe to do so.

Walking: One of the Best Medicines We Have

Fortunately, the news is not all negative. The human body remains remarkably adaptable throughout life. The same systems that weaken through inactivity can improve when challenged appropriately.

Walking remains one of the most effective forms of exercise available. It strengthens the legs, challenges balance, improves cardiovascular fitness, promotes healthy circulation, encourages deeper breathing, supports bowel function and helps maintain independence. Walking also benefits mental wellbeing, reducing anxiety and improving mood. For many people, it provides social interaction and a sense of purpose as well as physical health benefits.

One of the most rewarding parts of my job is seeing people rediscover what they are capable of. I have worked with countless patients who have been struggling physically, whether following illness, surgery, injury or simply a prolonged period of inactivity, and seen significant improvements in their strength, mobility and confidence through a structured rehabilitation programme. Progress does not require extreme exercise or hours in the gym. More often, it begins with simple steps: standing up more frequently, walking around the house regularly, performing targeted strengthening exercises and gradually increasing daily activity levels. Small changes, performed consistently, can lead to remarkable improvements over time.

The Bottom Line

The hidden danger of "just sitting down more" is that the effects develop slowly enough to feel normal. A little less walking becomes weaker muscles. Weaker muscles reduce confidence. Reduced confidence leads to less movement. Over time, strength, balance, fitness and independence can all be affected.

The good news is that movement remains one of the most powerful medicines we have. Our bodies are designed to move, and in most cases they respond remarkably well when we give them the opportunity.

References

1. Kortebein P, Ferrando A, Lombeida J, Wolfe R, Evans WJ. Effect of 10 days of bed rest on skeletal muscle in healthy older adults. JAMA. 2007;297(16):1772-1774.

2. Dirks ML, Wall BT, van de Valk B, et al. One week of bed rest leads to substantial muscle atrophy and induces whole-body insulin resistance in the absence of skeletal muscle lipid accumulation. Diabetes. 2016;65(10):2862-2875.

3. Sherrington C, Fairhall NJ, Wallbank GK, et al. Exercise for preventing falls in older people living in the community. Cochrane Database of Systematic Reviews. 2019;1:CD012424.

4. Convertino VA. Cardiovascular consequences of bed rest: effect on maximal oxygen uptake. Medicine & Science in Sports & Exercise. 1997;29(2):191-196.

5. Brower RG. Consequences of bed rest. Critical Care Medicine. 2009;37(10 Suppl):S422-S428.