How To Do Cardio As An Ectomorph Without Losing Muscle

How to do cardio without losing muscle mass? To do cardio whilst holding on to muscle mass, especially as an ectomorph, you need to do low intensity steady state cardio for a maximum duration of 20 – 30 minutes whilst keeping your heart rate below 70 beats per minute.

As an ectomorph it takes a lot of hard work to build muscle and just as much to maintain it. If you do this naturally then you are better equipped to hold onto this muscle for longer and to really lost muscle mass you would need to not be stimulating or providing it with adequate nutrition for a significant period of time that your body adapts to your new activity level. 

As it’s such a priority for people to hold onto muscle there is also a priority to avoid doing something that will see a negative impact on muscle mass, the victim is cardio. Cardio has been seen as a killer of gains, when a bodybuilder goes on a bulk to build muscle they will just eliminate cardio, some at an extreme end that they don’t even want to walk to the shop because it will burn calories that could go towards building muscle. 

This is a crazy mentality however there is some rational behind it, just look at a long distance runner compared to a short distance sprinter. Sprinters could be mistaken for looking like a bodybuilder whereas a long distance runner wouldn’t fill out a size small t-shirt. 

This of course comes down to genetics, training style and a range of other factors but as an ectomorph you will already have the genetics to be in the long distance runner image so need to do as much as possible to move towards a sprinters image. 

The Two Types Of Cardio

When it comes to cardio you can separate them into two categories, low intensity steady state cardio (LISS) and high intensity interval training (HIIT).

Low intensity steady state cardio targets the aerobic system and makes use of the muscles slow oxidative fibre type (most commonly found in higher percentages in an ectomorph). This is why ectomorphs tend to excel at endurance based cardio, taking the cardiovascular systems capabilities out of it the muscles are actually more suited to this type of training/cardio due to fibre make up. 

High intensity interval training targets the anaerobic system and predominantly uses fast twitch muscle fibres, these provide high bursts of energy output but this cannot be sustained over long distances or for a long duration of time.

The difference between LISS and HIIT comes down to how you use them as a form of cardio, LISS is an extended form of cardio that keeps your heart rate around 60bpm – 70bpm and is low impact, walking is the best example of this. HIIT on the other hand involves short bursts of energy over a smaller duration of time, this could be sprints on a treadmill where you’d do a 20 second sprint followed by a 10 second jog, this process would be repeated from anywhere from 5 – 20 minutes. 

Do Low Intensity Steady State Cardio

When it comes to maintaining muscle mass as an ectomorph and still wanting to include cardio in your weekly routine (which would be advised as it benefits cardiovascular health) then your safest route would be to focus on LISS. 

The reason HIIT became so popular over the years is because it’s a quick and effective way to burn calories, LISS burns calories too but at a much slower rate, and hour walk for example might burn 200kcal where as a 15 minute HIIT session could burn 400kcal. 

The benefit then of including LISS is that it will still do the job of getting your heart pumping blood around the body, in the process delivering nutrient rich blood to the muscles. What you need to be cautious of is overdoing it and turning the session into a full workout that would be alongside a weightlifting session. 

To get the most out of the LISS session you need to cap it to a maximum of 30 minutes and make sure your heart rate doesn’t go above 70bpm, once this happens you are no longer doing low intensity and this has now become a workout. Therefore a half hour walk a few times a week, preferably on your non training days so that it can be a form of active recovery, will ensure you don’t burn a load of calories and help to maintain muscle mass. 

Vary Your Cardio Activities

Even though I recommend the half hour walk that’s not to say this is the best option for everyone and this is for two reasons. The first is that you should enjoy the cardio activity that you choose, walking might be incredibly boring for you and therefore you won’t want to do it, the second is that it should also compliment your weight training sessions. 

The first point is that walking is not the only form of LISS cardio, cycling, swimming even rowing can all be forms of LISS provided that you keep your heart rate low and don’t let it turn into a marathon session. 

The second point is that if you’ve done a heavy leg session on Monday then you will need Tuesday to recover at a minimum, getting blood pumping to aid recovery is beneficial but walking we not necessarily be beneficial to this because it predominantly uses the leg muscles. A better option would be something like swimming because the leg muscles are secondary for this and it is a low impact form of cardio. 

Keeping your cardio varied will keep you engaged with it and as long as you are stimulating but not ‘working’ your muscles through the form of cardio that you decide to do, you won’t lose muscle mass including it.

Daily Calories And Protein Requirements

The final point that isn’t directly related to cardio however is essential for maintaining muscle mass and that is to make sure your daily protein intake is adequate enough to maintain muscle mass. Regardless of whether or not you do cardio making sure you get enough protein daily to cover your requirements is essential. 

A minimum protein intake for anyone that works out and lifts weights should be 1g per pound of body weight. If you weigh 200lbs then your daily protein intake should be a minimum of 200g. Protein is the building block of your muscles and if you are not consuming enough on a daily basis to maintain your base requirements then you will likely lose muscle mass regardless of whether or not you do cardio.

If you are worried about losing muscle mass by doing too much cardio but actually consume a calorie surplus everyday then this is another reason to go ahead and do your cardio without worrying about it affecting your muscle mass. If you are in a calorie surplus then any energy expended during cardio will just go towards the surplus and even further if you have a body fat percentage of 13% and over then the cardio will go towards burning fat and not muscle degradation.

Keep your calories and protein intake sufficient enough and cardio will have no impact on muscle mass and could even benefit it through any minimal stimulation as a result.


Cardio is named such because it targets the cardiovascular system and not the bodies musculature. As fast twitch muscle fibres have such a strong impact on muscle hypertrophy doing sprints can actually build muscle mass but in general cardio is a tool to be used to burn calories and body fat. 

If you are eating in a calorie surplus and have adequate protein intake then you shouldn’t be worried about cardio having an adverse effect on your muscle mass, however if you want to be sure then restrict your cardio to LISS and keep your heart rate below 70bmp and you will be fine.

What Next

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