You've probably seen the Swiss ball ham curl before. And if you've never done it, it might remind you of something you'd see on those cheesy workout DVDs your mom uses as dust collectors.

On paper, the exercise seems comical, almost pathetically simple. But in practice, it'll make you wonder how the hell something so basic could be so challenging.

If the standard version is too easy for you, then take it up a notch with this.

The Single-Leg Eccentric Hamstring Curl

How to Do It

1. Lay on your back with one foot on the Swiss ball (leg should be straight) and the other foot on the floor (leg bent).
2. Curl the ball in towards you while keeping your hips and foot on the floor.
3. Extend your hips up to the ceiling and lift your foot off the floor.
4. Keeping your hips up, slowly straighten your leg for a 3-5 second eccentric/negative.
5. Repeat for 6-10 reps on each side.

Perfecting the Swiss Ball Ham Curl

Here's a list of common mistakes people make when attempting both types of Swiss ball ham curls. If you can prevent these, then you'll be far more likely to pack some muscle onto your hams.

• No hip extension: One of the most challenging aspects for beginners is to maintain hip extension throughout their set. Dropping the hips too low with no extension limits your potential range of motion.
• No upper back engagement: Your upper back is your connecting point to the floor. With no engagement in the upper back, you'll have no balance. Press your hands or elbows into the floor and squeeze the hell out of your upper back.
• No tempo: Instead of moving as fast as possible to get the set over with, try a 3-4 second eccentric count each rep.
• Shortened range of motion: One of the most challenging aspects of leg curls from the floor is extending the leg straight towards the finishing portion of the exercise. Most people will shorten their range of motion and cut themselves off at about three-fourths of the way through. If you do this, you're missing a huge chunk of potential gains! Go through a full ROM to reap the full rewards.
• No eccentric loading: When most people do leg curls, they focus solely on the concentric or lifting portion of the exercise (curling the ball in toward the body). Loading the eccentric portion (straightening the leg) with a slow tempo creates greater tension and puts far more demand on the hamstrings.