Does Cardio Interfere with Strength Training? A Research-Based Look

Francisco Inzunza
Sep 22
3 min read

Does Cardio interfere with strength training?

A common concern for athletes and lifters is whether adding cardio will hurt their strength and muscle gains. Research on concurrent training (doing resistance training and endurance training together) has tried to answer this question. Here’s a breakdown of key findings from multiple studies, simplified for practical use.

The Interference Effect

When you combine strength training with cardio, there’s a potential for what’s called the ‘interference effect.’ This means your strength and muscle gains might not be as large compared to doing strength training alone.

The degree of interference depends mainly on:

• Frequency of cardio sessions

• Total volume (how much time you spend on cardio)

• Type of cardio (e.g., running vs. cycling)

Lower frequency, lower total volume, and lower impact modes of cardio (like cycling instead of jogging) cause less interference. Still, even with these adjustments, the effect is not fully eliminated.

Does Intensity Matter?

High Vs. Moderate Intensity Cardio

Interestingly, this study found that the intensity of endurance training (moderate vs. high intensity) doesn’t significantly change the interference effect as long as the total training volume is matched. Both moderate-intensity cardio and high-intensity intervals led to similar reductions in strength gains.

However, moderate-intensity cardio was rated as easier per unit of workload, meaning it might be more sustainable in practice compared to HIIT.

Timing of Cardio and Strength Workouts

Another key factor is timing. In this study, strength training was performed immediately after cardio. This setup may have amplified the interference effect. Better strategies include:

• Doing strength training before cardio

• Separating cardio and strength sessions by several hours

• Performing them on different days

These strategies help reduce fatigue and molecular interference, especially important when doing HIIT.

Impact on Muscle Growth and Body Composition

There were small, non-significant differences between groups in body composition changes. One interesting note: participants doing moderate-intensity cardio gained slightly more lean body mass in the lower body compared to those doing high-intensity cardio, but the differences were small and not statistically significant. This means the results shouldn’t be over-interpreted.

Practical Applications

What the research shows

From this study, here are the main takeaways for athletes, bodybuilders, or anyone balancing lifting with cardio:

1. If maximum strength and hypertrophy are your goal, limit cardio as much as possible.

2. If you do cardio, both high-intensity and moderate-intensity training interfere with gains to a similar degree.

3. Moderate-intensity cardio may be easier to recover from than HIIT, making it a practical choice.

4. Try to separate cardio and lifting sessions by time (hours or days) for the best results.

5. Type of cardio matters — lower-impact options like cycling are better than high-impact ones like running.

Conclusion

Cardio doesn’t have to destroy your strength or muscle-building progress, but it can limit the maximum gains you achieve. To minimize the interference effect, keep cardio low in frequency and volume, prefer lower-impact modalities, and separate it from your lifting sessions. Moderate-intensity cardio may be the most efficient balance between effort and recovery.