Should you exercise with sore muscles after a workout?

If you feel achy after a run or a gym workout, you may be unsure whether to carry on training or allow your body time to recover.

This muscle ache or stiffness after exercise is called "delayed onset muscle soreness" (DOMS). It typically begins 12–24 hours after a workout and commonly reaches its worst point 24–72 hours later.

In most cases, DOMS resolves entirely within three to five days. But what should you do while it lasts? Can you exercise when you are still sore? Here is what the evidence indicates.

Why muscles become sore after a workout

During exercise, small tears, sometimes referred to as "microtears", develop in the muscles. As the body sends fluids and nutrients to the affected area to repair these tears, inflammation occurs. This is a normal part of recovery and helps promote gains in muscle size and strength.

However, inflammation also activates pain receptors, leaving you sore in the days following a workout.

The degree of soreness you experience depends on the activity involved. DOMS is more likely if you have not exercised for some time, try a new form of activity, or place a substantial load on your muscles, such as through weight training or running.

In simple terms, it is your muscles responding to an activity that is more difficult or demanding than they are used to.

The more regularly you perform the same type of exercise, the less likely you are to become sore.

Do you need to be sore after every workout?

Muscle soreness is entirely normal, particularly when you are starting to exercise. However, it is not always a reliable sign that you are making progress.

It simply shows that your body is adjusting to a new kind of exercise or a sudden rise in training load.

It does not show whether that workout was successful in building muscle or improving fitness - particularly if you have been training consistently while gradually increasing your load or frequency.

For instance, a person who runs frequently will probably not feel sore after one running session, but that session can still improve their fitness.

Likewise, if you regularly lift weights, using weights that are heavier than normal may cause only mild DOMS at most. Even so, every session will still contribute to stronger muscles and increased muscle mass.

Should you exercise if you are still sore?

The answer depends on whether injury or performance is your main concern.

Training as you recover from DOMS will not harm you. However, some evidence indicates that soreness may reduce strength and performance. In practice, this means you may be unable to lift as much weight or run as quickly while experiencing DOMS.

Research has also found that muscle damage may impair balance. This could raise the likelihood of a fall or an injury, including a sprained ankle.

Another study found that soreness can reduce skill performance - basketball shooting accuracy in this instance. You may therefore notice an effect if your exercise has particular performance goals.

DOMS, recovery and rest days

Having recovery days between workouts does not appear to make much difference to long-term gains in fitness or strength.

Studies have compared training on consecutive days - such as Monday, Tuesday and Wednesday - against training on non-consecutive days, such as Monday, Wednesday and Friday.

They have found no apparent difference.

For example, one study asked two groups to complete the same full-body weight-training routine for seven weeks, either across three consecutive days or three non-consecutive days. Both groups achieved similar gains in muscle size and strength.

Similarly, another study compared two groups of cyclists following the same high-intensity interval training programme on either three consecutive days or three non-consecutive days. After three weeks, the groups had made the same overall improvements in aerobic fitness and time-trial performance.

These studies were comparatively short. It is therefore also possible that, across a full training year, taking the occasional rest day may help you stay motivated and prevent injury.

Bottom line

Although you will probably feel more stiff or sluggish, exercising with sore muscles will not hurt you and is unlikely to hold back your training progress.

You may, however, wish to avoid activities that depend on balance, including intensive jumping and landing exercises, because your injury risk could be slightly higher.

If you are very sore, there is some evidence that massage or even an ice bath may support recovery, though the benefit is small.

Muscle soreness is normal, but it remains important to pay attention to your body. Never train through severe discomfort or pain, as it may signal an injury.

You should speak to a doctor if:

• your muscles are extremely sore and the soreness continues for more than seven days
• you have visible bruising around the sore muscle
• you experience sharp pain.

Hunter Bennett, Lecturer in Exercise Science, University of South Australia

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