Cardio Burns Fat but May Be "Detrimental to Your Muscle Gaining," According to an Expert

"It depends on the type of cardio that you're doing," Rondel told POPSUGAR. "If you're doing steady-state cardio, which is a long duration above 30 minutes, that could be detrimental to your muscle-gaining goals." Steady-state cardio can be detrimental to building muscle "because that can put you into a zone where you're developing more stress hormones (cortisol), which can be counterproductive to developing muscle," Rondel explained. The influx of cortisol in your body can potentially break down tissue, he said.

Instead of going for hour-long runs, Rondel recommends getting in your cardio with activities like high-intensity interval training (HIIT). This is because a HIIT workout creates an anabolic response as "it's done above your anaerobic threshold, which elicits a hormonal response (growth hormone and testosterone) that is conducive to gaining muscle," he said.

"I think there are benefits to integrating both (cardio and strength training) into your workout program," Rondel said. Partaking in cardiovascular activities by hiking, cycling, dancing, swimming, walking, and running long-distance are a great way to reverse cardiovascular disease, according to a 2017 article in the World Journal of Cardiology. The benefits of cardio go beyond a number on the scale, which is why you shouldn't cut it out completely. But if your goal is to gain muscle, cardio shouldn't be your main focus, according to Rondel. Instead, he recommends implementing styles of training like Tabata into your weightlifting sessions. Here are examples of a Tabata workout.

Rondel recommends strength training a minimum of two to three days per week. For cardio, he said you can do it every day, but it depends on the intensity. You can do two to three days of HIIT per week and three to four steady-state days a week as long as they aren't longer than 30 minutes a session, he explained.

If you're wondering how to fit all of these workouts into your weekly schedule, Rondel said two-a-days aren't necessary. Instead, do 30 minutes of strength and 30 minutes of cardio, such as HIIT, in the same workout. Rondel also recommends doing compound exercises, like squats and deadlifts, during your strength sessions to build muscle and burn fat. Complete a minimum of three to four sets and 10 to 12 reps per exercise to build muscle.

Strength training will definitely help you gain muscle, but you'll also want to keep your stress levels low (stress causes your body to produce more cortisol) and eat in a calorie surplus to develop more muscle tissue. Calculate your daily caloric needs to build muscle with this equation.

Sleep is also important if you're trying to build muscle. You should aim to get seven to nine hours of sleep each night to increase your muscle mass, according to a previous interview with Rizwana Sultana, MD, assistant professor of pulmonary critical care and sleep medicine at the University of Texas Medical Branch.

Building muscle won't happen overnight, but choosing the right cardio, lifting weights, manageing stress levels, and fueling your body with adequate nutrients is a great place to start.