Medical professionals have increasingly realised that, as soon as possible after, or even during, a hospitalisation or illness that necessitates time in bed, patients should begin physical therapy to avoid or lessen these effects. Some of these are listed here:
Effects on the muscles and bones
The musculo-skeletal system functions best when supporting the body in an upright posture against gravity. The weight-bearing muscles of the neck, abdomen, lower back, buttocks, thighs and calves are particularly important for this purpose, and the deterioration caused by bed rest affects these muscles most seriously.
When muscles aren’t used, they rapidly begin to weaken and atrophy (waste away). Strength can decrease as much as 20-30% after only a week of complete bed rest, and it generally takes much longer to regain the strength than it took to lose it.
Decreased muscle strength, together with other structural changes to the nerves and muscles, affects co-ordination and balance, and increases the risk of falls.
Bed rest also causes the bones to lose density because they aren’t performing their normal weight-bearing function. The leg bones are the most likely to be affected. Thinner bones increase the risk of fractures, even with minor falls.
Immobility can also lead to limited joint movement. The cartilage around joints begins to deteriorate, while the connective tissue thickens and the muscles shorten, typically at the hip, knee and shoulder. This negatively affects walking and daily activities.
Effects on the heart and blood
Like the muscular system, the cardiovascular system functions best when the body is in an upright position, working against gravity. After just a few days of bed rest, blood starts to pool in the legs. On standing, this can lead to dizziness and falls.
Immobility also causes the heart to beat more quickly, and the volume of blood pumped is lower. The volume of blood generally in the body is lower, and there is less oxygen uptake by the body. This results in poorer aerobic fitness and fatigue sets in more easily.
The blood also becomes thicker and stickier, which increases the risk of a blood clot forming, especially in the legs (deep vein thrombosis) and the lungs (pulmonary embolism).
Effects on the lungs and blood
Bed rest increases the risk of pneumonia and atelectasis (collapse of lung tissue).
Fluid tends to build up in the lungs because the muscles aren’t working to remove excess fluid from the body. It’s harder for the lungs to expand when you’re lying flat, so blood pools in the chest area, leading to decreased lung volume. Coughing is not as effective due to weakened abdominal and chest muscles, causing mucus to collect in the lungs.
Breathing also becomes shallower, which leads to poorer oxygen-carbon dioxide exchange in the lungs.
Effects on the skin
Bed sores or pressure sores are a kind of skin ulcer and are a common result of the additional pressure placed on parts of the body resting on the bed surface: the blood supply to the skin covering these parts becomes insufficient.
Effects on digestion and excretion
Constipation is common, due to several factors including decreased mobility, decreased fluid intake, decreased peristalsis (movement of the digestive tract) and incomplete emptying of the bowels.
Appetite is often suppressed in bedridden patients, and malnutrition and dehydration may occur if proper attention is not paid to diet.
Prolonged bed rest also makes urination less effective. The bladder is harder to empty and tends to retain fluid, which can lead to infection. There is also greater excretion of urinary calcium, which raises the risk for bladder and kidney stones.
Incontinence due to bed rest is also common: disorientation, confusion and decreased mobility can all contribute to this problem.
Effects on the metabolism and hormonal system
Prolonged bed rest can cause numerous complex changes in the balance of hormones and minerals in the body, and in how the body processes energy.
For example, immobility causes a reduction in the percentage of lean mass to body fat, and raises the risk of developing diabetes: immobile muscles can develop reduced insulin sensitivity, which in turn leads to raised blood sugar levels.
Effects on the brain
Bed rest in combination with the stress of illness are associated with increased risk for various mental health and cognitive issues, including anxiety, depression, irritability, apathy, sleep disturbances and confusion.
Many of these ill effects can be greatly reduced by short spells of mild activity – every little bit helps, even if only getting up to walk a few steps every day. Some exercises can even be done while lying down, if you aren’t yet able to stand easily. Be sure to plan and follow an exercise and recovery programme in consultation with your health professionals.
(Health24, October 2013)
Kristin J. et al. The physiological consequences of bed rest. Journal of Exercise Physiology. Volume 10 Number 3 June 2007
Strax, T et al. 2004. Summary: Effects of Extended Bed Rest—Immobilization and Inactivity. Demos Medical Publishing, Inc.