OK, you're tired, you've worked out for four days straight, and it's leg day. What's your secret weapon to get the most out of this routine? A pre-workout? That's a good start. But to ensure you're able to give your best effort and destroy every muscle fiber in your lower body, pay attention to your pre-workout nutrition, not just supplementation.
Choosing the right type and amount of carbohydrates is invaluable during every workout, but especially ones where you're tired and have a big workload on paper. Carbohydrates are your muscles' primary energy source. If they're lacking, your performance will suffer. Don't go into this workout empty!
You may also consider sipping on carbohydrates and BCAAs during your workout. This added fuel will help you push through the seemingly never-ending sets of split squats and lunges!