If you've only got 20 minutes to train, focus on opposing muscle groups with sets of ab and calf exercises used in place of rest breaks.

Some might opt for cardio with such a short period of time to train, but you can get a great workout that elicits a hypertrophy response and a massive amount of EPOC (Exercise Post Oxygen Consumption) if you do it right.

For safety and efficiency, don't lift heavy weight for this. It looks almost like a circuit. Here's an upper body example:

Group One

Do three rounds of this:

• Machine Chest Press: Use a weight sufficient to achieve muscle failure by 20 reps.
• Any Ab Exercise: Do 12-15 reps.
• Machine Row: Aim to hit muscle failure by 20 reps.

Take only 15 seconds rest and sip some Plazma™ between rounds.

Group Two

Do three rounds of this:

• Steep Incline Dumbbell Press: Use a weight sufficient to achieve muscle failure by 20 reps.
• Any Calf Exercise: Do 12-15 reps.
• Lat Pulldown: Hit muscle failure by 20 reps.

Take only 15 seconds rest and sip some Plazma between rounds.

The key is to take no rest between the three exercises and only 15 seconds between rounds. Working opposing muscle groups and doing an ab or calf exercise between them will afford you some degree of strength recovery between sets.

If you push yourself you'll knock this out in 20 minutes, be rewarded with a killer pump, and the excess post-exercise oxygen consumption will keep you thermic for hours.