Balancing Cardio and Strength Training: How to Protect Your Muscle Gains

For health-conscious individuals who regularly engage in both cardiovascular exercise and strength training, a common concern is whether cardio negatively affects muscular gains. On this issue, Elizabeth Ushry, a certified athletic trainer with Baptist Health Orthopedic Care, offers clarity and guidance rooted in exercise science.

The distinction between cardiovascular training and strength training lies in the energy systems they primarily rely upon. In a recent Instagram reel, Ms. Ushry explains: “With cardio workouts, you're actually going to be taking all of your energy from your fat stores found in your body … for longer duration type of workouts. With weight training, you're actually taking all of your energy from your glycogen stores found within your muscles.”

Cardio, which generally involves sustained, rhythmic movements such as running, cycling, or using an elliptical  (a stationary exercise machine used to stair climb), pulls energy from fat stores – primarily in the form of triglycerides within adipose tissue (fat) and intramuscular triglycerides (fat within muscle fibers).

Strength training, in contrast, relies on quick, high-intensity movements such as lifting weights or performing bodyweight exercises, and taps into glycogen stores for energy. “Glycogen stores” refer to the body's stored form of glucose, primarily in the liver and muscles, which are utilized as energy during physical activity.

Because of this fundamental difference, performing cardio and resistance training without proper balance can create challenges for those aiming to build or maintain muscle.

The Risks of Improper Cardio Placement

One of the key messages Ushry emphasizes is that cardio does not inherently interfere with muscle development—if done correctly. She acknowledges the ongoing debate in fitness communities: “There's a lot of controversy on whether or not cardio will negatively or positively impact your muscular gains, and I'm here to clear that out for you a little bit.”

In our Instagram reel, hear from Elizabeth Ushry, a certified athletic trainer with Baptist Health Orthopedic Care.

Ushry warns that the interference effect—where cardio may blunt strength gains—can occur, but only under certain conditions. “When you do cardio, it can negatively affect your muscular gains if you don't follow these simple, simple rules. It deals with the intensity of the cardio, where you place your cardio within your workout, and the type that you do.”

These three variables—intensity, timing, and type—are crucial. High-intensity cardio performed immediately before strength training can deplete glycogen stores and fatigue the muscles, leaving them less capable of handling resistance work. Similarly, excessive cardio after weight training may impair recovery.

Guidelines for Optimal Integration

Ushry’s personal and professional approach favors a moderate, well-structured integration of both exercise forms. “I weight train about three times a week. I found from research that if you do 20 to 30 minutes of mild to moderate type of cardio—I'm talking treadmill … Stairmaster on a low level, or an elliptical—you're actually going to maximize your fat burning potential within your body, instead of hindering your muscle gains.”

This recommendation aligns with research suggesting that low to moderate-intensity cardio—when done either after strength sessions or on alternate days—can support cardiovascular health and fat metabolism without compromising muscle development.

Best Practices for Exercisers

Based on Ushry’s guidance, health-focused individuals who want to retain or increase muscle mass while also improving cardiovascular fitness should consider the following best practices:

1. Moderate Intensity: Aim for mild to moderate cardio, such as walking on a treadmill, using a stair stepper on a low setting, or light elliptical work, especially when performed close to strength training.
2. Time It Right: If combining cardio and weights in a single session, consider doing strength training first. This allows for maximum effort when lifting and reduces the likelihood of fatigue-induced injury.
3. Separate When Possible: For those training multiple times per week, alternating cardio and strength days or performing them at separate times of day may enhance both outcomes.
4. Keep It Short: Limiting cardio to 20–30 minutes ensures that energy is used efficiently without depleting reserves needed for muscle repair and growth.
5. Stay Consistent: A consistent approach, even with moderate cardio, can improve fat metabolism while maintaining lean muscle mass—especially when paired with a protein-rich diet and sufficient recovery.

Cardiovascular exercise and strength training do not have to be at odds. For active individuals, the key is balance—using strategic timing, intensity, and duration to enjoy the benefits of both exercise modalities without sacrificing hard-earned muscle.

As Ms. Ushry makes clear: “If you do 20 to 30 minutes of mild to moderate type of cardio … you're actually going to maximize your fat burning potential within your body, instead of hindering your muscle gains.”