Okay, it's time to up the ante. Most weeks, this column deals with exercises that the average Joe or Joe-lene can do. But this week, we're going for the jugular.

These exercises recommended by California Fitness trainer Troy Teo (top picture) are tough enough to challenge even seasoned gym rats.

Done carefully, they can be a welcome break in routine.

Teo, 24, who trains clients at the fitness chain's Novena Square outlet, believes in challenging his body every now and then. After all, muscle memory means that our body gets used to exercises after a while and doesn't work as hard as it did.

To do this, he takes everyday exercises like lunges and front dumbbell raises and does them on the Bosu - an inflated half-ball with a hard plastic base. It can be used as an exercise tool on both the soft semi-circular side and the hard flat side. Hence the name Bosu (Both Sides Utilised).

Game enough to try them?

If you want personal training from Troy Teo, call California Fitness on 6250-2345.

The Bosu is available from Cyber Health at 28 Jalan Lokam for $250. Call 6289-5594.

DUMBBELL RAISE

What it works: Quadriceps, front shoulders, core

How to do it: Stand with one leg on the Bosu and hold a dumbbell in your right hand. While maintaining your balance, exhale and raise the dumbbell to shoulder height and return to start position as you inhale. Do three sets of 15 repetitions with each arm.

Precaution: Do not lift the dumbbell above the collar bone and do not fully straighten the knee.

BALL RAISE WITH LUNGE

What it works: Hamstrings, glutes, shoulders, core

How to do it: Stand with both legs on separate Bosus, right leg in front of the left, and hold a medicine ball (or any heavy object such as a book) in both hands near your front thigh. While lunging forward with your right leg, exhale and raise the ball over your head. Return to start position as you inhale. Do three sets of 15 repetitions with each leg in front.

Precaution: Do not lift the ball so much that it goes behind your head and don't bend the knee more than 90 degrees when doing the lunge.

STEP UP AND TWIST

What it works: Quadriceps, obliques, core

How to do it: Stand with your right foot on the Bosu and hold a medicine ball in both hands at chest level. Step onto the Bosu and exhale as you twist your torso (taking the ball to your left) and lift your left knee. Inhale and return to start position. Do two sets of 15 repetitions with each leg in front.

Precaution: Don't overdo the twist and always maintain a steady posture.

This article was first published in Urban, The Straits Times on Apr 24, 2008.