You’ve had a cold or the flu and your symptoms have begun to subside. Your nose has stopped dripping, your cough is clearing and your head and muscles no longer ache.

You’re ready to get off the couch. But is it too early to go for a run? Here’s what to consider when getting back to exercising after illness.

Exercise can boost your immune system – but not always

Exercise reduces the chance of getting respiratory infections by increasing your immune function and the ability to fight off viruses.

However, an acute bout of endurance exercise may temporarily increase your susceptibility to upper respiratory infections, such as colds and the flu, via the short-term suppression of your immune system. This is known as the “open window” theory.

A study from 2010 examined changes in trained cyclists’ immune systems up to eight hours after two-hour high-intensity cycling. It found important immune functions were suppressed, resulting in an increased rate of upper respiratory infections after the intense endurance exercise.

So, we have to be more careful after performing harder exercises than normal.

Can you exercise when you’re sick?

This depends on the severity of your symptoms and the intensity of exercise.

Mild to moderate exercise (reducing the intensity and length of workout) may be OK if your symptoms are a runny nose, nasal congestion, sneezing and minor sore throat, without a fever.

Exercise may help you feel better by opening your nasal passages and temporarily relieving nasal congestion.

However, if you try to exercise at your normal intensity when you are sick, you risk injury or more serious illness. So it’s important to listen to your body.

If your symptoms include chest congestion, a cough, upset stomach, fever, fatigue or widespread muscle aches, avoid exercising. Exercising when you have these symptoms may worsen the symptoms and prolong the recovery time.

If you’ve had the flu or another respiratory illness that caused a high fever, make sure your temperature is back to normal before getting back to exercise. Exercising raises your body temperature, so if you already have a fever, your temperature will become high quicker, which makes you sicker.

If you have COVID or other contagious illnesses, stay at home, rest and isolate yourself from others.

When you’re sick and feel weak, don’t force yourself to exercise. Focus instead on getting plenty of rest. This may actually shorten the time it takes to recover and resume your normal workout routine.

I’ve been sick for a few weeks. What has happened to my strength and fitness?

You may think taking two weeks off from training is disastrous, and worry you’ll lose the gains you’ve made in your previous workouts. But it could be just what the body needs.

It’s true that almost all training benefits are reversible to some degree. This means the physical fitness that you have built up over time can be lost without regular exercise.

To study the effects of de-training on our body functions, researchers have undertaken “bed rest” studies, where healthy volunteers spend up to 70 days in bed. They found that V̇O₂max (the maximum amount of oxygen a person can use during maximal exercise, which is a measure of aerobic fitness) declines 0.3–0.4% a day. And the higher pre-bed-rest V̇O₂max levels, the larger the declines.

In terms of skeletal muscles, upper thigh muscles become smaller by 2% after five days of bed rest, 5% at 14 days, and 12% at 35 days of bed rest.

Muscle strength declines more than muscle mass: knee extensor muscle strength gets weaker by 8% at five days, 12% at 14 days and more than 20% after around 35 days of bed rest.

This is why it feels harder to do the same exercises after resting for even five days.

But in bed rest studies, physical activities are strictly limited, and even standing up from a bed is prohibited during the whole length of a study. When we’re sick in bed, we have some physical activities such as sitting on a bed, standing up and walking to the toilet. These activities could reduce the rate of decreases in our physical functions compared with study participants.

How to ease back into exercise

Start with a lower-intensity workout initially, such as going for a walk instead of a run. Your first workout back should be light so you don’t get out of breath. Go low (intensity) and go slow.

Gradually increase the volume and intensity to the previous level. It may take the same number of days or weeks you rested to get back to where you were. If you were absent from an exercise routine for two weeks, for example, it may require two weeks for your fitness to return to the same level.

If you feel exhausted after exercising, take an extra day off before working out again. A day or two off from exercising shouldn’t affect your performance very much.

Ken Nosaka, Professor of Exercise and Sports Science, Edith Cowan University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

What’s the difference? is a new editorial product that explains the similarities and differences between commonly confused health and medical terms, and why they matter.

Changes in thinking and memory as we age can occur for a variety of reasons. These changes are not always cause for concern. But when they begin to disrupt daily life, it could indicate the first signs of dementia.

Another term that can crop up when we’re talking about dementia is Alzheimer’s disease, or Alzheimer’s for short.

So what’s the difference?

What is dementia?

Dementia is an umbrella term used to describe a range of syndromes that result in changes in memory, thinking and/or behaviour due to degeneration in the brain.

To meet the criteria for dementia these changes must be sufficiently pronounced to interfere with usual activities and are present in at least two different aspects of thinking or memory.

For example, someone might have trouble remembering to pay bills and become lost in previously familiar areas.

It’s less-well known that dementia can also occur in children. This is due to progressive brain damage associated with more than 100 rare genetic disorders. This can result in similar cognitive changes as we see in adults.

So what’s Alzheimer’s then?

Alzheimer’s is the most common type of dementia, accounting for about 60-80% of cases.

So it’s not surprising many people use the terms dementia and Alzheimer’s interchangeably.

Changes in memory are the most common sign of Alzheimer’s and it’s what the public most often associates with it. For instance, someone with Alzheimer’s may have trouble recalling recent events or keeping track of what day or month it is.

We still don’t know exactly what causes Alzheimer’s. However, we do know it is associated with a build-up in the brain of two types of protein called amyloid-β and tau.

While we all have some amyloid-β, when too much builds up in the brain it clumps together, forming plaques in the spaces between cells. These plaques cause damage (inflammation) to surrounding brain cells and leads to disruption in tau. Tau forms part of the structure of brain cells but in Alzheimer’s tau proteins become “tangled”. This is toxic to the cells, causing them to die. A feedback loop is then thought to occur, triggering production of more amyloid-β and more abnormal tau, perpetuating damage to brain cells.

Alzheimer’s can also occur with other forms of dementia, such as vascular dementia. This combination is the most common example of a mixed dementia.

Vascular dementia

The second most common type of dementia is vascular dementia. This results from disrupted blood flow to the brain.

Because the changes in blood flow can occur throughout the brain, signs of vascular dementia can be more varied than the memory changes typically seen in Alzheimer’s.

For example, vascular dementia may present as general confusion, slowed thinking, or difficulty organising thoughts and actions.

Your risk of vascular dementia is greater if you have heart disease or high blood pressure.

Frontotemporal dementia

Some people may not realise that dementia can also affect behaviour and/or language. We see this in different forms of frontotemporal dementia.

The behavioural variant of frontotemporal dementia is the second most common form (after Alzheimer’s disease) of younger onset dementia (dementia in people under 65).

People living with this may have difficulties in interpreting and appropriately responding to social situations. For example, they may make uncharacteristically rude or offensive comments or invade people’s personal space.

Semantic dementia is also a type of frontotemporal dementia and results in difficulty with understanding the meaning of words and naming everyday objects.

Dementia with Lewy bodies

Dementia with Lewy bodies results from dysregulation of a different type of protein known as α-synuclein. We often see this in people with Parkinson’s disease.

So people with this type of dementia may have altered movement, such as a stooped posture, shuffling walk, and changes in handwriting. Other symptoms include changes in alertness, visual hallucinations and significant disruption to sleep.

Do I have dementia and if so, which type?

If you or someone close to you is concerned, the first thing to do is to speak to your GP. They will likely ask you some questions about your medical history and what changes you have noticed.

Sometimes it might not be clear if you have dementia when you first speak to your doctor. They may suggest you watch for changes or they may refer you to a specialist for further tests.

There is no single test to clearly show if you have dementia, or the type of dementia. A diagnosis comes after multiple tests, including brain scans, tests of memory and thinking, and consideration of how these changes impact your daily life.

Not knowing what is happening can be a challenging time so it is important to speak to someone about how you are feeling or to reach out to support services.

Dementia is diverse

As well as the different forms of dementia, everyone experiences dementia in different ways. For example, the speed dementia progresses varies a lot from person to person. Some people will continue to live well with dementia for some time while others may decline more quickly.

There is still significant stigma surrounding dementia. So by learning more about the various types of dementia and understanding differences in how dementia progresses we can all do our part to create a more dementia-friendly community.

The National Dementia Helpline (1800 100 500) provides information and support for people living with dementia and their carers. To learn more about dementia, you can take this free online course.

Nikki-Anne Wilson, Postdoctoral Research Fellow, Neuroscience Research Australia (NeuRA), UNSW Sydney

This article is republished from The Conversation under a Creative Commons license. Read the original article.