Should I do cardio if I am trying to increase muscle size?

As long as your caloric and resistance training recommendations are being met, you can still perform cardio training while trying to increase size. However, the amount of aerobic exercise you perform may need to be reduced. Assuming you are consuming the proper amount and types of calories to accommodate your cardio, muscle gain should not be affected. Performing cardio training can support your efforts in resistance training because it maximizes the ability of the cardiorespirtory system to supply or recover from all types of activity- including weight lifting. To maximize muscle growth be sure to consume an adequate amount of healthy calories and perform strength training exercises.

While cardiovascular exercise can be reduced if you are trying to gain muscle, it is important to keep it in your routine. Regular cardio is not only good for burning fat, but also your overall health and wellbeing. In addition, to gain muscle, you will need to be consuming more calories than you burn. There is a tendency to gain some fat along with muscle when you are eating this way. Regular cardio can help limit the amount of fat gained during this phase. 20-40 minutes of walking, 3-4 times a week would be a good place to start.