If your goal is weight loss, perform cardio at the start of a workout and follow with strength training.
Beginning with cardio can provide a higher total caloric expenditure because of a physiological element called excess post-exercise oxygen consumption, which is known as the " afterburn" effect from exercise.
If your goal is muscle gain, start with weight training so you have sufficient energy to put toward the strength portion of your workout. But to maximize your energy levels for strength training, it's ideal to separate your cardio workout days from weight-training days.
