Suck your nuts up.
I'm mainly talking to the guys out there, as most of us boys have have no idea what on earth a pelvic floor is, let alone the location of the damn thing. Besides, the title doesn't really resonate with the opposite sex. However, you girls may learn a thing or two, so listen in. Here's a simple solution for understanding how to engage your pelvic floor and protect your lower back.
How often have you heard, or possibly even said yourself, "I can't deadlift, it hurts my back"?. Deadlifts, squats and similar exercises are often avoided due to back pain. Lack of mobility, flexibility and core strength are the main contributors to this. All of these areas must be optimal in order to perform such exercises efficiently, however, I'll leave mobility and flexibility for another day - today is all about your core.
Now the boring bit, I'll keep it brief. What is your core? It is not your abs! Most of us think that your core and abdominals are the same thing, this is not quite correct. Your core is a group of four muscles located deep inside the abdominal wall, so definitely not your '6 pack'. One of those essential core muscles is your pelvic floor. So, when you engage your pelvic floor your core activates. Now, the big questions - how do we activate it, and why is it so important.
Firstly, your spine is not designed for taking great loads. By activating your core, it will support and protect your spine, therefore your lower back will be safe and sound. If you girls have nailed pelvic floor activation due to child birth and a life of Pilates, then you're one step ahead. Now fellas, when you squeeze those muscles around your 'man area' - when urinating, climaxing, clenching your rectum or performing penis exercises, you're actually activating your pelvic floor, therefore your core is switched on.
How does this apply to making gains, you ask? Well, before you next pick a weight off the floor or descend on a squat, take a deep breath in, engage those muscles and perform the lift. Another really important point is to keep your breath held during the lift, and exhale once the repetition is complete, or during a sticking point on heavy lifts.
On the topic of heavy lifts, your core can actually replace your weight belt. Essentially a weight belt is doing exactly what your core should be doing, and by wearing one, it weakens your core and inhibits it from working when you don't have your trusty belt on. If you're competing in World's Strongest Man or an Olympic Power Lifter, wearing a weight belt is perhaps neccesary, but if you're not then ditch the belt, drop the weight and suck your nuts up.