Should you do cardio BEFORE or AFTER your weight training session?
This is a great question that I want to help you understand. The first and most important thing to consider is the type of athlete you are ( yes you are ALL athletes to me regardless of fitness level). Are you an endurance athlete or a strength/physique athlete?
Let's start with an endurance athlete. If this is your main training domain, say a marathon runner or you do triathlons you should prioritize cardioand endurance training first. You should use weight training on the "off" running days or cross training days of your programming.
Now if you are an athlete who is doing a physique competition like bodybuilding OR you are trying to be as strong as possible, weight training should take priority before cardio. The reason is simply because you are wanting to put ALL your effort into lifting to get as strong as you can or obtain the physique you want before your cardio session. Doing cardio can deplete your glycogen and energy stores that can be utilized for training.
However, you can do the 2 day split up which many of my physique clients turn to when they are doing a lot of cardio which is to do cardio in the morning ( or night depending on your schedule) and then weight training at the opposite time frame. This way your body is recovered and fueled properly for the heavy weight training session. It is very hard to push through a 2 hour + workout without fatigue and exhaustion setting into place. This can hinder your training and most certainly your recovery.
All of the above mentioned is with steady state or long duration cardio. Now you can do a HIIT session which is high intensity interval training along with your weight training session. At first you will feel completely spent if you are doing your HIIT right. You will be tired from your weight training session and you are just going in there to give it all you got for your cardio. If you are doing a leg day and only have 2 HIIT sessions a week, it's smarter to grind out your HIIT on leg day as opposed to the next day because then you are taxing your legs every day of the week.
In the end, it really just comes down to what your goals are and what you schedule allows you to do. Regardless, finding the habits of getting in the groove again are most important. Find what you enjoy and do that.