Too Much Cardio Can Cost You Muscle

Build the engine, but don’t burn the chassis

Photo by Ryan De Hamer on Unsplash

You can’t, and shouldn’t, avoid “cardio”. In fact, it’s right in there as one of the five pillars of intelligent training.

[embed]The 5 Pillars of Intelligent Training After 40 Most fitness advice isn’t built for you.medium.com

Having a strong cardiorespiratory system is fundamental for aging athletes. A strong aerobic engine improves recovery between strength sets and supports heart and metabolic health, as well as body composition. It also helps you sustain effort longer and recover faster.

Done well, cardio is not the enemy of strength. But it can be. Too much of anything can be counterproductive, including cardio training.

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Excessive Cardio

The catch?

When cardio becomes excessive, it can start to work against the very thing many adults over 40 need most, and that’s muscle mass.

Muscle is not just about looking strong or looking good; it is your reserve currency for aging well. It supports posture, balance, insulin sensitivity, joint health, independence, and long-term resilience.

Lose enough of it, and everything else gets harder.

The issue is not aerobic training itself, but more so, the issue is too much cardio without enough strength training, recovery, protein, and fuel.

Long, frequent, high-volume cardio sessions can create a large energy demand. If you take a look at endurance athletes such as marathon runners, you’ll quickly notice how little upper body muscle mass they carry.

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That may be fine in the short term, and after all, they are training for a specific event where weight and muscle may be detrimental to the results they are seeking.

It’s over the longer term where this can present a problem, particularly if you are also dieting aggressively, under-eating protein, or skipping resistance training, your body has little reason to preserve muscle tissue.

Over time, you may become lighter, but not necessarily stronger, healthier, or more capable.

This is where some people get body composition wrong, where they chase more calories burned instead of more capacity built.

They add another run, another ride, another sweaty session, but they are not lifting heavy enough, eating enough protein, or recovering well enough to maintain muscle.

This is precisely why, for aging athletes, the goal is not simply to do more cardio. We need to be more intentional and balanced in our exercise program.

The goal is to build an aerobic engine that supports strength, not one that competes with it.

Zone 2

Zone 2 work is one of the best tools for this. It is low-intensity, conversational, and sustainable. If you can hold a conversation while exercising, then you’re essentially in “Zone 2”. When the conversation starts to be a little more “one-word responses”, then you’re leaving Zone 2 and moving into the higher, more anaerobic zones.

Zone 2 may not look impressive on social media, but it builds the foundation. It improves aerobic capacity without creating the same recovery cost as constant high-intensity work.

The sweet spot for combining strength and cardio training should be based on the following:

• Lift to preserve and build muscle.
• Use cardio to support recovery, heart health, and endurance.
• Eat enough protein to give your body the materials it needs.
• Recover hard enough to adapt.

Cardio should make you more capable, not leave you flat, weak, and constantly tired. Not so long ago, I was setting PRs in my running and adopted a 6-day-a-week running schedule. It didn’t leave much room for resistance training, and while it was nice to feel fitter and faster, the associated strength loss and feeling were not so nice!

The Aerobic Engine is not about endless miles or punishing workouts. It is about rebuilding aerobic capacity so you can sustain effort longer, recover faster, and support the metabolic health that underpins long-term performance.

Build the engine. Just don’t burn the chassis.

Thank you for reading. My aim is to provide guidance on strength and longevity, helping people maintain a quality of life as they age and continue doing the things they enjoy.

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