Ask anyone in a gym which type of training you should do first and you'll usually get one of three answers.
3. I don't know.
The 'I don't know" people are correct in that they are telling the truth. The other two groups are either right or wrong.
Over the years the argument went backwards and forwards as to which to do first. [Things are cyclic, what is fashionable today won't be in a few years, then some time later it will be the latest craze yet again.]
Some people say resistance first - a portion of them are right, the rest are wrong.
Some people say cardio first - a portion of them are right, the rest are wrong.
How is that possible?
A few of those asked will have done their research and know exactly which they should be doing first. Others are going by whatever method was in fashion when they first started working out, or worse, because someone in the changing room told them that's how you have to do it.
The truth is, neither is entirely correct. To say "Do cardio/resistance (delete as appropriate) first" will not work for everyone.
You need to look at your goals (and to some degree your training programme). If you want to be lifting the heaviest weight you have ever lifted, you're unlikely to do that after a 5 mile run.
If you want to get a new PB on a 5KM run, you are unlikely to do that after multiple sets of lifting weights for the last hour.
So what are your goals? Do you have a training programme? Is it working for you?
If not and it all seems a bit unclear then get in touch.