Deciding whether to lift weights on cardio days depends largely on your fitness goals, your current fitness level, and how you structure your workouts. There is no universal answer, but understanding the interaction between cardio and weightlifting can help you make an informed choice.
Weightlifting and cardio serve different but complementary purposes. Weightlifting primarily focuses on building muscle strength and size, while cardio improves cardiovascular endurance and heart health. Combining both can enhance overall fitness, but the timing and intensity matter.
If your main goal is to build muscle or increase strength, it is generally better to prioritize weightlifting before cardio during the same session. This is because intense cardio performed first can deplete glycogen stores—the stored form of carbohydrates your muscles use for energy—leading to fatigue and reduced strength performance. For example, high-intensity interval training (HIIT) or long-duration cardio before lifting can impair your ability to lift heavy or perform enough reps to stimulate muscle growth effectively[1].
On the other hand, if your primary goal is to improve cardiovascular endurance or lose fat, doing cardio first or on separate days might be more beneficial. Low-intensity cardio such as walking or light cycling can serve as a warm-up before lifting weights without significantly impacting strength performance. Some people prefer to do cardio and weights on different days to allow full focus and recovery for each modality. For instance, a weekly routine might include three days of full-body strength training and three days of cardio, which balances both systems without overtaxing the body[2].
Cardio does not inherently “kill gains” or prevent muscle growth. This is a common misconception. When done in moderation and combined with proper nutrition and rest, cardio can actually support muscle growth by improving heart and lung function, which enhances recovery between sets and overall training capacity. Problems arise only when cardio is excessive, nutrition is inadequate, or recovery is insufficient. In such cases, the body may not have enough resources to repair and build muscle effectively[3].
Integrating cardio and weightlifting in the same session can be efficient and effective if planned well. For example, bootcamp-style workouts alternate between cardio intervals and strength exercises, keeping the heart rate elevated while building muscle and endurance simultaneously. This approach can save time and provide a comprehensive workout that improves both cardiovascular fitness and muscular strength[2].
The amount of cardio you should do depends on your goals. For weight loss and general health, aiming for 50 to 60 minutes of combined cardio and strength training per day, at least five days a week, is recommended. This can include 20 to 30 minutes of cardio most days, mixed with two to three strength training sessions weekly. Pairing this with a solid nutrition plan is crucial for achieving results safely and sustainably[4].
In summary, lifting weights on cardio days is not only possible but can be beneficial if done thoughtfully. Prioritize your main goal: if muscle gain is the focus, lift weights first or on separate days from intense cardio. If cardiovascular health or fat loss is the priority, cardio can come first or be done on alternate days. Balance, nutrition, and recovery are key to making both cardio and weightlifting work together effectively.
Sources:
[1] rawathletic.club
[2] onepeloton.com
[3] icicilombard.com
[4] womenshealthmag.com
