So, does cardio kill gains? Not if you program it intelligently. The real muscle killers are: doing too much high-intensity cardio, eating too little, and recovering poorly.
Most people can do cardio and grow muscle at the same time.
When Cardio Can Hurt Muscle Gains
- Too much HIIT. Intervals pile stress on top of lifting.
- Too big of a deficit. If you are cutting hard, recovery suffers.
- Poor sleep. You cannot out-train poor recovery.
How to Add Cardio Without Killing Gains
| Cardio Type | Best Use | Rule of Thumb |
|---|---|---|
| LISS / Zone 2 | Fat loss, recovery, conditioning | 2-5 sessions/week is usually fine |
| HIIT | Time-efficient fitness | 1-2 sessions/week max for most |
Best Weekly Setup for Lifters
If you lift 3-5 days/week, this is a solid default:
- Keep most cardio easy (walks, incline treadmill, easy bike).
- Do hard cardio on a separate day from heavy legs when possible.
- Eat enough protein and do not slash calories too aggressively.
Cardio Is Actually Good for Gains (Sometimes)
Easy cardio improves work capacity and can help you recover between sets. Better conditioning often means better training quality.
Frequently Asked Questions
Should I do cardio before or after lifting?
If gains are the priority, lift first. Put cardio after, or on separate days.
Will running kill my leg gains?
A little running will not. High mileage plus heavy lifting can be a recovery problem. Use mostly easy runs and keep volume sane.
Build Your Weekly Plan With AMUNIX
AMUNIX helps you plan lifting and cardio in one schedule - and keep your weekly volume realistic so you can recover and progress.
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This article is educational and not medical advice. If you have joint pain or cardiac risk factors, consult a clinician before increasing training volume.