25-Minute Workout

Stars like Lady Gaga and Rihanna save time when they work out by using celebrity trainer Harley Pasternak's 5-Factor workout philosophy: 25-minute workouts, five days a week.
Harley's workouts break down to a simple formula: five minutes of cardio, 15 minutes of strength training, and five more minutes of cardio to cool down. This may not sound like much, but trust me: it's effective! After experiencing my own 25-minute Harley workout at a recent training camp sponsored by Subway, I was thoroughly convinced — and sore. If you want to try it yourself, then do the following workout, which is a favorite of Harley's because you're either lying down or seated for the entire strength-training portion of the workout. "I love that you're focusing on muscle fatigue rather than general fatigue," he says.
To begin, start and end with five minutes of cardio, like jumping jacks or jogging. Then grab a mat, a medicine ball, two dumbbells, and an exercise ball, and repeat the following three-move circuit four times (for a total 15 minutes).

Lying Hamstring Ball Curl

After warming up with five minutes of cardio, do the lying hamstring ball curl:

• Start by lying flat on your back with an exercise ball under your heels. Bridge your hips up and hold that position through the entire exercise.
• Flex your feet and dig your heels into the ball. Place your arms straight out to your side for support. (Don't use them during the move, though; they are just for support.)
• Slowly roll the ball toward your body as you curl your heels. Make sure to keep your hips in the bridge position; don't thrust them toward the ceiling as you do the move.
• Slowly return to the start position (straight legs, hips bridged) to complete one rep.
• Do 20 reps.

 

Lying Triceps Extension

Here's how to do a dumbbell lying tricep extension:

• Grab a set of dumbbells (pick a size that will fatigue your arms after 20 reps) and start by lying on your back.
• With one dumbbell in each hand, raise your arms so they are above your chest, making sure your elbows are straight but not locked.
• Slowly lower both arms toward your head, bending your elbows at 90 degrees as the dumbbells reach the mat. Aim to lower your dumbbells so they are on either side of your head, elbows bent and pressing in toward your head.
• Lift arms back up to starting position. This is one rep.
• Do 20 reps.

 

Seated Ball Twist

The end of the circuit is a seated trunk twist with medicine ball. Here's how to do it:

• Grab a medicine ball (try a five-kilogram one to start) and sit on the ground with your knees bent and your heels about two feet from your bum.
• Lean slightly back without rounding your spine at all. It is really important to keep your back straight; this makes the move more difficult, but be sure you don't let your back round.
• Hold the ball so it is in front of your chest and your palms are facing each other.
• Pull your navel to your spine and twist slowly to the right. The movement is not large and comes from the ribs rotating, not from your arms swinging. Inhale through center and rotate to the left. This completes one rep.
• Do 20 reps.
• If you want to make the move more difficult, then try lifting your heels off the ground (like in the top photo).

After completing these three moves, repeat the circuit three times and end with a five-minute cardio cool down (like jogging or jumping).