The physiology of fat burning is pretty well understood. Hormone-sensitive lipase is the key player for stoking the process, mobilizing free fatty acids from adipose tissue so those little globs of fat can be dumped into the blood. Then, carnitine transports the free fatty acids into the mitochondria where they can be burned for energy.

What's less understood about the physiology of fat burning is the number of factors that can hinder it. One thing is certain: a crappy workout with low metabolic cost will not make you burn fat. So how do you get your adipose tissue to release more fatty acids from training? It's simple but it ain't easy: add the finishers I'm about to describe into your workouts.

What's a finisher? It's an intense exercise, or combination of exercises, that stimulates all the major muscle groups to induce the highest metabolic cost possible. Basically, it's the longest 5 or 10 minutes of your life. And just like the name implies, it should be performed at the end of your workout. There are two reasons why.

First, your available energy stores are lower than normal after a strength training session. This depletion creates the ideal time to augment the demand for energy since your metabolism will trigger hormone-sensitive lipase in adipocytes in order to provide this energy. Translation: you can stimulate a helluva lot of fat burning at the end of a workout.

Second, if you do a finisher correctly, you won't want to do anything afterwards. A finisher should be exhausting up to the edge of nausea, and even though you might feel a bit queasy for a few minutes, you can take pride in the fact that you stoked your fat-burning engine that had been stored away since last summer. The proton accumulation and muscle acidification that caused the nausea are a powerful stimulus for fat loss.

I'm assuming you're a guy or gal who's already in pretty decent shape but is smooth around the midsection. The following four finishers are organized from easiest to toughest, but they're all uniquely intense in their own way.

This combination is popular because it only requires a kettlebell. You can do it almost anywhere, and it's probably the easiest of all five.

How to do it:

• Start with as many kettlebell swings as possible in 30 seconds
• Rest 30 seconds
• Then do as many clap push-ups as possible in 30 seconds
• Rest 30 seconds
• Next do swings hard and fast for 20 seconds
• Rest 20 seconds
• Follow it up with 20 seconds of clap push-ups
• Rest 20 seconds
• Finish with 10 seconds of swings, 10 seconds of rest, and 10 seconds of clap push-ups
• Rest for 30 seconds and repeat the sequence once more

The band jump squat and judo push-up is an awesome combination, but it becomes pretty brutal when you have to knock out 150 total reps as fast as possible. Get ready for pain.

How to do it: Start with 15 band-jump squats, then drop to the ground (keep the band on) and do 15 judo push-ups. The next round is 14 of each. Continue dropping a rep each round until you reach 10. Make rest your nemesis and keep it at bay from start to finish.

This challenging complex can be performed with a kettlebell or a dumbbell in each hand. It's an ideal finisher for people that are short on time and don't have a lot of space to move, but it's also great for everyone else that wants to burn fat and build their anaerobic threshold.

How to do it: Stand with feet shoulder-width apart while holding a weight in each hand, arms hanging at sides. Push the hips back and squat until the weights are just below the knees. Quickly stand up as you simultaneously curl the weights and then dip down a few inches and push-press the weights overhead using leg assistance. This entire movement should be smooth without any hesitation. Bust off as many hard and fast continuous reps as possible in two minutes.

This is my favorite ass-kicking, nausea-inducing finisher for athletes. However, it's also the most impractical because most people don't have a sled to push, and if they do it's probably nowhere close to a pull-up bar or a set of rings. Still, I couldn't write an article on finishers without mentioning it.

How to do it: Start by pushing a sled back and forth, hard and fast, along a 20-meter stretch for as many rounds as possible in 60 seconds. Next, jog to the pull-up bar or rings and perform as many reps as possible in 60 seconds (you'll most likely need to stop at least once during that time to avoid hitting failure, because if you do hit failure, it'll probably be impossible to knock off anymore reps in that time). Then jog back to the sled, push it hard for 50 seconds and jog over for 50 seconds of pull-ups (again, avoid failure). The next round is 40 seconds of each, followed by 30 seconds and 20 seconds of each. Finish with the hardest, fastest 10 seconds of the sled push and pull-ups your body can muster.

Note: I've built a thick skin due to the insults that were hurled at me from athletes after they regained consciousness from this finisher.

Of course, any of these finishers can be performed with different exercises, but I recommend you stick with the basic parameters outlined above because they've been battle-tested. Add one of the finishers to the end of your workouts, 3-4 days per week, and you'll start scorching body fat as you build muscle and mettle.