Quick cardio: these six workouts blast fat, tone your butt and legs and ease holiday stress—in 15 minutes flat!

Shape, Dec, 2005 by Julie Osterman

It's easy to get stressed out when you can't fit your regular workouts into your schedule. But you don't have to let your fitness slide when you're short on time. Whether you have 15, 30 or 45 minutes to spare, you can keep off the holiday pounds with one (or more) of these six goal-oriented cardio plans, created by Scott McLain, personal training manager at The Westerville Athletic Club in Columbus, Ohio. "In the ideal world, you do want to go longer than 15 minutes," McLain says. "But with people's busy schedules, especially around the holidays, it's always better to do something than nothing." Pick a program and take the plan with you to the gym. All the details are here, so no excuses!

1. ENDURANCE TRAINER

GOAL Increase your endurance.

WHY IT WORKS By increasingly working at a slightly harder pace than usual and maintaining a steady pace, you can train your heart to work efficiently for the long haul.

MACHINE Elliptical trainer, set on manual.

SPEED     MIN.  LEVEL  RPE

moderate  5     4-5    5
moderate  5     6-7    5-6
moderate  5     8-9    6

BONUS 5: Do 3 minutes at RPE 6-7 and 2 minutes at RPE 5.

CALORIES BURNED 140* (190 with Bonus 5)

TRAINER'S TIP Breathe from your diaphragm, not your chest. Use your breath to help maintain a steady pace.

*CALORIE BURNS ARE BASED ON A 145-POUND WOMAN.

2. BUTT BOOSTER

GOAL Shape, lift and tone your rear.

WHY IT WORKS "Your gluteus maximus isn't really that active when you're walking or running horizontally," McLain says. "But when you add an incline or step, you're moving your hip through a full range of motion, which really targets the butt and quads."

MACHINE Treadmill, set on manual. You'll lower your speed as you
continue to raise the incline.

SPEED (MPH)  MIN.  INCLINE  RPE

4.0-4.3      1      4%      4
4.0-4.3      2      6%      5
3.5-4.0      4      8%      5
3.5-4.0      1     10%      5-6
3.5-4.0      1     12%      6
4.0-4.3      4      8%      5
4.0-4.3      2      6%      4

BONUS 5: Insert this peak climb after the last segment of 4 minutes at 8
percent.

3.5-4.0      2     10%      6
3.5-4.0      2     12%      6
3.5-4.0      1     15%      6

CALORIES BURNED 120 (175 with Bonus 5)

TRAINER'S TIP To maximize butt work, keep treadmill speed slow enough to take full strides on the incline, pushing off back foot and contracting glutes with each step.

3. INTENSE CALORIE BLASTER

GOAL Burn maximum calories in a short period of time by doing high-intensity interval training.

WHY IT WORKS "The more intense the activity, the more calories you burn per minute," McLain says. "When you do a very high-intensity interval, then recover, you're challenging your cardiovascular system."

MACHINE Treadmill, no incline, set on manual.

ACTIVITY                         MIN.  RPE

power walk (4.4-4.7 mph) or      1     8
fast run (6.5-8 mph)
light jog or walk (3.5-4.0 mph)  1     4

Repeat interval 6 more times (12 minutes).

power walk or fast run           1     8 

BONUS 5: Do a 30-second all-out sprint at RPE 9, recover for 2 minutes
at RPE 3, then repeat.

CALORIES BURNED 100-160 (130-190 with Bonus 5)

TRAINER'S TIP Push your RPE on the high end of the interval, so that at the end of the minute you feel as if you can't go much longer.

4. HIKER

GOAL Total lower-body toner.

WHY IT WORKS Using a stepper or gauntlet (also called a stepmill) requires your knees and hips to move through a larger range of motion than other cardio machines, which targets your entire bottom half.

MACHINE Stepper or gauntlet, set on manual.

ACTIVITY  TIME     LEVEL  RPE

push      45 sec.  4      6
recover   45 sec.  2      4
push      45 sec.  5      6
recover   45 sec.  3      4
push      45 sec.  6      6-7
recover   45 sec.  4      4
push      45 sec.  7      7
recover   45 sec.  5      4
push      45 sec.  8      7
recover   45 sec.  5      4

Repeat entire sequence (7 1/2 minutes).

BONUS 5: Set resistance and speed as high as you can handle for 5
minutes (RPE 6-7).

CALORIES BURNED 200 (255 with Bonus 5)

TRAINER'S TIP If you can't fully catch your breath during recovery, drop down a level.

5. SHORT 'N' SWEET

GOAL A low-intensity yet effective workout to perform before strength training or any other activity.

WHY IT WORKS Using multiple machines gives you more bang for your buck, even though you're working at lower intensities. The first 5 minutes on the treadmill and the bike train the same muscles--especially the buttocks--but with different movements, while the final steady-state treadmill run gives you a total-body finish.

MACHINE Treadmill and upright bike.

MACHINE          SPEED         MIN.  RPE

Treadmill,        2-2.5 mph    5     5-6
12-15% incline,
walk
Upright bike,    70-85 rpm     5     5-6
moderate
resistance
Treadmill,        5.7-7.0 mph  5     5-6
0% incline, run

BONUS 5: Hop on the bike for 5 more minutes at the same RPE, or choose a
third machine that includes upper-body work such as a VersaClimber,
rower or dual-action elliptical machine at RPE 5-6.

CALORIES BURNED 125-140 (165-180 with Bonus 5)