How Much Cardio Is Too Much?

Cardio is arguably the most important type of exercise. After all, it develops your heart, lungs, and circulatory system, which are responsible for keeping you alive. There is also a strong link between cardio and long-term health. Regular cardio training can help ward off numerous life-shortening diseases, including (1):

• Cardiovascular disease
• Stroke
• Chronic obstructive pulmonary disease (COPD)
• High blood pressure (Hypertension)
• Diabetes (Type 2)
• Metabolic syndrome
• Obesity
• Certain types of cancer (e.g., colon cancer, breast cancer)

Cardio is also a valuable weight loss tool and combined with a kilocalorie-controlled diet, it can help you burn fat and get lean.

While it’s hard to argue with the benefits of cardio, you can have too much of a good thing. In fact, excessive amounts of cardio can negatively impact your fitness and health.

In this article, we explore the risks and symptoms of doing too much cardio and provide advice on how to find the right balance for weight loss and cardiovascular health.

What is the Recommended Amount of Cardio?

When it comes to cardio, there is an accepted minimal dose that most people should strive to achieve. This amount of cardio will help you develop a reasonable fitness level while reducing your risk of numerous diseases.

According to the Centers for Disease Control (CDC), adults over the age of 18 should get (2):

• 150 minutes of moderate-intensity physical activity each week OR
• 75 minutes of vigorous-intensity activity each week OR
• A combination of both

The CDC also suggests doing more than the minimum amount of cardio will provide even better health and fitness benefits. Consequently, while there are clearly defined lower limits for cardio, there are currently no recommended upper limits.

That makes sense, given that some exercisers spend many hours each week doing cardio. For example, as a young triathlete, I often clocked up 15 hours a week of cardio.

However, there are downsides to doing too much cardio, and it’s essential to strike a balance between training and recovery.

The Dangers of Excessive Cardio

Firstly, it’s important to stress that what is excessive cardio for one person may be perfectly acceptable for another. The optimal amount of cardio depends on your fitness goals, experience, and ability to tolerate and recover from this type of training.

For instance, a top-flight marathoner needs to do more cardio than a recreational exerciser. Subsequently, the “right” amount of cardio varies from person to person.

However, regardless of your fitness and goals, it’s entirely possible to do more cardio than your body can cope with. The effects and dangers of excessive cardio include:

Heart and Arterial Damage

Moderate amounts of cardio are good for heart, lung, and circulatory health. However,  research published on PubMed suggests that prolonged, excessive cardio can cause pathological changes to these structures, impairing their function. These changes include coronary artery calcification, diastolic dysfunction, and large-artery wall stiffening (3).

Impaired Immunity

Regular cardio exercisers enjoy better health and are typically sick less often than their non-exercising counterparts. This is due to the immunity-boosting effect of exercise. However, excessive cardio can suppress the immune system, leading to more frequent and longer-lasting illnesses (4).

Hormone Imbalances

Your body uses hormones as chemical messengers, instructing organs and systems how to function. Excessive cardio can have a negative effect on male and female hormone balance (5). This can affect overall homeostasis, leading to a host of problems, including:

• Altered metabolism
• Reproductive issues
• Reduced bone mass
• Altered mood
• Disrupted sleep patterns
• Difficulty recovering from exercise

Increased Risk of Injuries

Excessive cardio can increase your risk of chronic and acute injuries. Chronic or long-term injuries are usually the result of repetitive movements combined with an inability to recover from high-frequency/high-volume training. In contrast, acute or sudden-onset injuries often happen because you are tired.

Many exercisers train through these issues, believing they’ll heal in time. However, what the body usually needs is time to rest and recover. Continuing to train usually delays recovery and means even minor injuries take longer to heal.

Impaired Muscle Growth

Moderate amounts of cardio can enhance strength and muscle gains. In fact, it’s also entirely possible to build a muscular physique while simultaneously developing a high level of cardiovascular fitness – known as hybrid training.

However, such a training approach requires careful planning, and too much cardio could impair muscle growth (6).

Excessive cardio causes cortisol levels to rise. Cortisol is a catabolic hormone, meaning its responsible for muscle breakdown. Too much cortisol will reduce muscle protein synthesis, which is one of the drivers of hypertrophy or muscle building.

Signs You Are Doing Too Much Cardio

So, how do you know if you are doing too much cardio? Look for the following signs and symptoms. If you are experiencing more than a couple, you probably need to reduce the duration and frequency of your cardio workouts.

Elevated Resting Heart Rate

Regular cardio exercisers usually have a lower resting heart rate (RHR) than their non-exercising counterparts. That’s because a strong, healthy heart can pump more blood per beat than a less fit heart. Consequently, it doesn’t need to pump as often. However, do too much cardio and your resting heart rate may increase.

A raised RHR suggests your body is working harder than usual, even though you are resting. Monitor your RHR and look for unexplained increases. An RHR more than 10% above normal suggests you need a break.

Related: Average Heart Rate for Athletes: Unlocking Peak Performance

Decreased Exercise Performance

A well-designed cardio program should gradually increase your fitness and performance. For example, you’ll be able to run further or faster, or your workouts will feel more manageable. These are signs that your body is adapting and can cope better with the demands of your training.

However, these adaptations depend on your ability to recover. Do too much cardio, and your body won’t have the time or resources it needs to improve your fitness. Consequently, your exercise performance may plateau, or, in the case of severe overtraining, it could noticeably decline.

Exercisers often make the mistake of trying to train harder when they hit a progress plateau. Unfortunately, this usually just makes matters worse, and a reduction in training frequency and intensity is what’s needed.

Related: Average Human Running Speed: How Fast Should You Be Running?

Constant Aches and Pains

While a little post-exercise muscle soreness is normal, aches and pains should not be constant companions. Feeling sore all the time is a reliable indicator you are overdoing things and would benefit from less cardio.

Most cardio-related discomfort is the result of repetitive movements, which can cause chronic inflammation. For example, runners typically experience ankle, knee, or hip pain. In contrast, swimmers are more likely to suffer from shoulder issues.

Training through pain invariably makes the issue worse. This is especially true with pain caused by inflammation.

Frequent Illness

Being ill all the time is a good indicator that your cardio workouts are suppressing your immune system. While it’s normal to get sick occasionally, if you seem to be suffering from more than your fair share of illnesses, you could be immunologically compromised.

Like injuries, it’s usually best not to train through illnesses. That’s especially true for anything that affects your respiratory system or results in fever.

Disrupted Sleep

Exercise can improve sleep quality and duration (7). However, too much cardio can disrupt your normal sleep pattern, making it even harder to recover from your workouts.

Most adults need 7-9 hours of sleep per night, and not getting enough sleep will severely undermine your progress. Trying to train hard while sleep-deprived is a recipe for poor performance and injury.

Related: The Importance of Sleep for Building Muscle and Losing Fat

FAQ’s

Do you have a question about the risks and signs of doing too much cardio? Don’t worry – I’ve got you covered! Alternatively, feel free to drop me a line in the comments section below, and I’ll get back to you ASAP.

1. Don’t I need to do a lot of cardio to lose weight?

Weight loss is a common reason some people feel they need to do a lot of cardio. This is understandable, given cardio’s reputation for burning kilocalories and fat. And while cardio can help you lose weight, it’s not actually the best option for most people.

The easiest and arguably most effective weight loss method is eating less. Consuming fewer kilocalories creates an energy deficit that will force your body to burn fat for fuel, leading to weight loss without exercise. Adding cardio into the mix should speed up a process already happening.

So, if you feel you need to do a lot of cardio to lose weight, it’s probably because you are eating too much. Lower your food intake, and you won’t need to do as much cardio.

2. Will doing cardio stop me from building muscle?

Contrary to what many people believe, cardio and strength training are quite compatible. There is very little evidence supporting the notion that a few weekly cardio workouts will stop you from building muscle.

However, because time and energy are limited, if muscle building is your priority, that’s where you should put most of your effort.

Do enough cardio to develop a reasonable fitness level while enhancing your health, i.e., by meeting the CDC’s recommendation of 150 minutes per week. Much more than this may detract from your primary goal.

3. Can I do cardio every day?

It’s okay to do cardio every day so long as you can recover between workouts and it’s compatible with your training goal, e.g., you are preparing for a marathon. Remember, if you are using cardio for weight loss, it’ll probably be easier to eat a little less rather than exercise more.

Also, it’s important to stress that cardio is only one type of fitness, and a well-rounded exercise program should also include strength and flexibility training. After all, these components are as important as cardiovascular fitness for most people.

Closing Thoughts

Cardio is good for everybody’s body. However, there is a point of diminishing returns, and more is not always better. In fact, excessive cardio can cause numerous problems and could even hurt your health.

Of course, if you are an endurance athlete, long and frequent cardio workouts are par for the course. But, for the average exerciser, the CDC’s recommendation of 150 minutes per week is an excellent target.

If you do choose to do more cardio, make sure you monitor yourself for signs that you are overdoing it. An elevated resting heart rate, chronic aches and pains, and frequent illnesses are all reliable indicators that you need to do less and pay more attention to rest and recovery.

Finally, remember that even hardcore lifters need to do cardio. After all, while big biceps, six-pack abs, or a massive bench press are cool, none of them matter much if your heart is small and weak. Cardio is a must if you want to live a long, healthy life.

References:

1. Agarwal SK. Cardiovascular benefits of exercise. Int J Gen Med. 2012;5:541-5. doi: 10.2147/IJGM.S30113. Epub 2012 Jun 22. PMID: 22807642; PMCID: PMC3396114.
2. Centers for Disease Control and Prevention. (n.d.). Physical Activity Basics – Adults.
3. O’Keefe JH, Patil HR, Lavie CJ, Magalski A, Vogel RA, McCullough PA. Potential adverse cardiovascular effects from excessive endurance exercise. Mayo Clin Proc. 2012 Jun;87(6):587-95. doi: 10.1016/j.mayocp.2012.04.005. Erratum in: Mayo Clin Proc. 2012 Jul;87(7):704. PMID: 22677079; PMCID: PMC3538475.
4. Hackney AC, Koltun KJ. The immune system and overtraining in athletes: clinical implications. Acta Clin Croat. 2012 Dec;51(4):633-41. PMID: 23540172.
5. Hackney AC, Lane AR. Exercise and the Regulation of Endocrine Hormones. Prog Mol Biol Transl Sci. 2015;135:293-311. doi: 10.1016/bs.pmbts.2015.07.001. Epub 2015 Aug 5. PMID: 26477919.
6. Markov A, Chaabene H, Hauser L, Behm S, Bloch W, Puta C, Granacher U. Acute Effects of Aerobic Exercise on Muscle Strength and Power in Trained Male Individuals: A Systematic Review with Meta-analysis. Sports Med. 2022 Jun;52(6):1385-1398. doi: 10.1007/s40279-021-01615-6. Epub 2021 Dec 8. PMID: 34878640; PMCID: PMC9124655.
7. Alnawwar MA, Alraddadi MI, Algethmi RA, Salem GA, Salem MA, Alharbi AA. The Effect of Physical Activity on Sleep Quality and Sleep Disorder: A Systematic Review. Cureus. 2023 Aug 16;15(8):e43595. doi: 10.7759/cureus.43595. PMID: 37719583; PMCID: PMC10503965.

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