I've recently written about how weak glutes can undermine and eventually derail your training. After working with hundreds of clients over the past 12 years I can say one thing with certainty. Weak butt muscles are an epidemic and, more than likely, you've got some work to do, too. Again, if you've got weak glutes it's not a matter of IF you will get a running injury, but WHEN.

The Marching Bridge a simple and effective exercise to build up that critical muscle group. Set up with your shoulder blades and head resting across a bench. Position your feet directly under your knees. Next, raise your hips up (not your low back) so that you form a straight line from your ears through your shoulders, hips and knees. Finally, bring your feet together and allow your knees to drift apart slightly.

Here's the BIG TIP: Be sure you are feeling the glutes doing the work. If you feel it in your lower back, you are attempting to arch your back. Shift the focus to your butt. If you feel it in your thighs, same thing – focus on getting your glutes to do the work.

Ok, now that you are forming the perfect bridge, it's time to challenge the strength and stability of your core and glutes. Lift one knee towards your chest while remaining perfectly still on the weight bearing side.

Many people have a tendency to slightly drop or rotate their hips the moment they lift their foot off the ground. If this happens, I suggest transferring your weight slowly so you can train yourself to react and stabilize appropriately.

Once your leg is raised, hold it there for 2-3 seconds before lowering it and switching legs. Remember, the key to this exercise is keeping your hips up and not allowing any drop or rotation. Marching quickly is not better – we are working on strength and the amount of time the glutes are put under tension matters!

The marching bridge falls between the entry level supine floor bridge and the more advanced hip thrust. Make sure you're choosing the correct exercise for your level.

*If your hamstring cramps up when you try this for the first time, 1) that should tell you something about how strong you aren't and 2) try regressing for a few sessions to the floor bridge.