There is a widespread misconception in the fitness world that cardio exercises limit "gains" or muscle growth, although research indicates mixed findings.
Hart says there's mixed research on whether cardio might hinder weightlifting and other strength training.
DOES CARDIO INHIBIT MUSCLE GAINS?
Hart explains how cardio may negate gym work. First, cardio can interfere with biochemical pathways important for strength training adaptations.
Why might cardio prevent muscle strength and size gains?
Another notion is that by mixing cardio and resistance training, individuals are fatiguing themselves and depleting energy stores
If you try to do too much in one workout session or without appropriate recuperation between sessions, especially if you don't eat enough calories.
Instead of conducting cardio and resistance training in one session, space them out by at least six hours, preferably 24.
Choose exercise based on your goals. The order of cardio and weights crucial, says Hart. Increasing strength or muscular size should come before cardio