Shock your body into torching fat & building muscle.

Most of the time your body needs a break between workouts (it's during those rest periods that big changes actually happen). But a few times a year, it's smart to put yourself through back-to-back H.I.G.T ( My high intensity group training ) workouts.

Overloading your muscles will keep them guessing, helping you break through any plateau. During this push, work every muscle three or four days in a row, performing sets with little or no rest in between.

Try it: Do my fast-paced circuit (exercises listed below). Complete 12 reps of each exercise (except for the plank—hold it for one 60-second set—going from one move to the next without rest). Repeat the entire circuit up to three times, resting for two minutes at the end of each circuit.

Pushups
Dumbbell Chest Press on Ball
Crunches on Ball
Plank (60 seconds)
Dumbbell Front Raises
Dumbbell Side Raises
Dumbbell Bicep Curls
Walking Lunges
Squats with Dumbbells
Box Jumps
Everyone's different—find the perfect workout for your body type.

Slow down
Adjusting the tempo of an exercise stimulates the muscle differently. The longer your muscles experience tension, the harder they work. During an exercise, count to two as you raise the weight, and count to four as you lower it. You'll spend more time in the lengthening phase of muscle contraction, which is more challenging and brings better results: a higher calorie burn during and after your workout.

Try it: During a chest press, count to two as you push the dumbbells toward the ceiling, and count to four as you lower them. During squats, count to four while lowering toward the floor, and then to two as you stand.

Split the difference

Do a full rep of an exercise, then do just half of it at the hardest part of the move. You sneak in extra reps and increase muscle tension in virtually the same amount of time, It also pumps lots of blood into the muscles, which is excellent for enhancing definition.

Try it: Grab a dumbbell in each hand, arms resting at your sides, palms facing forward. Without moving your upper arms, curl the weights toward your shoulders, then slowly lower them halfway down; stop and raise them back to your shoulders. Lower back to start. That's one rep.

Step it up

Speed work isn't good only in cardio. Increasing speed during any exercise burns more calories. It also boosts power, which helps improve athleticism. My favorite, speed rope work. Skip rope as intensely as you can for 15-30 second intervals. Do this for up to 5-10 minutes.

Try this 20-minute ab workout, designed especially for women.

Try it: To fully tax muscles do fast reps of a bodyweight exercise after a version using weights. You'll recruit different muscles and break down more muscle fiber (which is good). For example, do a set of chest presses, then do 10 to 20 quick pushups; or perform 12 alternating lunges with dumbbells followed immediately by 10 to 20 body-weight squats.

Get off the ground

Plyometrics—think leaping, jumping or skipping—burns calories and builds lean muscle quickly. Working against gravity increases the load, and jumping incorporates different muscle fibers, which makes your workout more intense.

Try it: Add plyo drills immediately after an exercise that works the same muscle group to power up your muscle fibers and help you squeeze out every last bit of juice you've got. (If you jump before exercising, your muscles will have less energy to perform the workout.) After a set of squats, do 10 squat jumps: Starting in the squat position, jump up and extend your arms overhead. Land softly with your knees bent and your arms swinging behind you.

Mix in cardio

Keep your heart pumping hard by combining your cardio and strength routines. Doing cardio between sets of weighted exercises burns a higher percentage of calories from fat. Try the speed rope work, it fits in here great.

Lose 10 pounds in 6 weeks with this ultimate running guide.

Try it: Instead of resting after a strength exercise, do at least 30 seconds of intense cardio, such as speed rope of basic jumping rope. If you do less intense cardio, like jogging in place, go for at least a minute.