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Can Cardio Ever Be Bad For You?

Cardio Exercise

Cardiovascular exercise is a crucial aspect of a healthy lifestyle. Defined as any exercise which incurs an increase in heart rate, examples of cardio include running, cycling, swimming, and exertive sports such as netball or basketball.


In fact, the CDC recommends that adults aged 19 to 64 perform either: 150 minutes of moderate cardiovascular exercise; or 75 minutes of intense cardiovascular exercise each week; in addition to strength training exercises on two days or more.

However, while there aren’t many instances in which cardio will be flat-out ‘bad’ for someone, there are situations where cardio may be counterproductive, depending on what someone wants to achieve; and there may be other instances where it might exacerbate an existing medical condition:

If your goal is to build muscle

There’s a long held misconception by many that if you want to increase muscle mass, then you should omit cardio from your workout and focus solely on weight training. However this isn’t strictly true. In fact, recent studies have suggested that performing some cardiovascular exercise in addition to weight training can actually boost muscle growth.

That said, it can be detrimental to these goals, depending on how you do it.

Putting in long shifts on the treadmill to create a calorie deficit, before heading over to the opposite end of the gym to hit the weights section could leave your body with no energy to spend. With fewer calories stored and available to burn, you’ll be less able to go through your rep routine.

So if your aim is to increase muscle mass, it’s important then to try and split your exercises into different sessions, so that you’re doing cardio and weight training on alternating days. Aim to lift 2-3 times per week, and fulfill your cardio obligations in between.

If you're fighting an illness

There are a number of theories that suggest that cardiovascular exercise is beneficial for the immune system, facilitates the body’s defenses against bacteria, and helps to reduce levels of those hormones which are conducive to feelings of stress.

But while cardio may have benefits in the prevention of illness, those who are in the process of fighting off or recovering from an illness should certainly make sure they rest, or exercise only in moderation.

Exercising while the body’s defenses are weakened may make it more susceptible to viruses or infection; so it’s always better to wait until you feel well enough before getting back on track.

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If you have an overuse injury

One of the drawbacks of some types of cardiovascular exercise (particularly those which are high impact, such as outdoor running or skipping rope) is their capacity to cause overuse injuries. This is where the affected joint or muscle is subjected to repetitive strain through exercise and not permitted enough time to repair itself.

In such instances, more exercise will obviously cause further damage and exacerbate the injury.

Again, those who have had an overuse injury shouldn’t completely omit cardio from their routine once they have recovered. But they should take a look at what they’re doing and re-assess with a healthcare professional, who might be able to suggest an exercise programme which protects the previously injured body part.

If you’re already doing enough in your day job

Some people’s occupations lend themselves to activity more than others. If a person’s job involves being on their feet all day and moving around (such as a park ranger or a gardener), they won’t need to do as much cardio in their spare time as someone who works in an office for instance, whose job is likely to be more sedentary.

The NHS recommends aiming for 10,000 (aerobic) steps a day. If you already hit this target during your normal hours of work, then it might be worth focussing more on something different to steady-state cardio when exercising in your spare time.

If you have exercise-induced allergies or asthma

As we’ve discussed, exercise remains crucial for everyone, whether they have a medical condition which presents an obstacle or not. But for those with conditions such as exercise-induced anaphylaxis or exercise-induced asthma, it’s certainly advisable to choose a cardiovascular exercise routine wisely.

In the case of exercise-induced anaphylaxis or EIA, a life-threatening reaction may occur when exercise is undertaken after ingesting a certain allergen; in such cases, exercise should be avoided and a doctor notified immediately.

Exercise-induced asthma can be brought on by steady-state cardio. It occurs when the airways react to the change in body temperature and humidity which takes place during exercise, and causes them to tighten, leading to breathing difficulties.

Taking an inhaler before a workout can help to reduce the likelihood of an attack; and choosing team sports, such as those typically requiring short bursts of energy instead of long periods of physical exertion (football, baseball or netball), may lower the risk of a flare-up too.