When To Do Weights First
For Fat Loss
A University of Tokyo study published in Medicine and Science in Sports and Exercise found that doing cardio after weight training burns more fat during the first 15 minutes of the cardio session than doing cardio before lifting.
To achieve fat loss, your body needs to use your stored fat as fuel for exercise. In order to do this, you must burn off your glycogen stores first. When you weight-train, you typically use glycogen as fuel. By doing weight-training first, you can burn the majority of your glycogen stores. So doing cardio
For Strength Goals
If you have specific strength goals, you definitely want to do your weight training first. Here's why: Your muscles are like a rubber band—it needs to be taut enough to restrict whatever it's wrapped around. For example, If you take the rubber band and repeatedly pull it, it becomes too loose and unable to hold objects together. Your muscles work the same way. The repetitive movements in cardio reduce your muscles' ability to contract effectively, leaving you disadvantaged if you're doing pure strength training and lifting for maximal effort right afterward.