Interval training offers no pain and lots of gain (and weight loss) in just 75 minutes a week.

The CDC recommends 75 minutes of high-intensity exercise per week. That sounds like a lot, but with interval training, you can break it up into chunks as short as 15 minutes at a time. In fact, current studies show that shorter workouts with peaks of intensity are more beneficial than long routines. Short workouts have been shown to increase metabolic rate and bone density, and can lengthen your life by an average of three years.

You can add interval training to most aerobic activities, including jogging, swimming, and biking. Vary your workouts, be sure to include muscle-strengthening activities along with aerobics, and build up slowly to avoid injury. As always, check with your health care provider before beginning any new routine.

You can find plenty of different approaches to interval training. Here's a simple one you can use with nearly any aerobic activity:

Step 1:Warm up. This part's important. You'll be hitting it hard, so make sure your muscles are ready. Using a stationary bike as an example: pedal slowly, breathing deeply and working at about 30 percent of your maximum effort. Be sure to complete the full two minutes of the warm up.

Step 2: Pick up the pace. For the next five minutes, alternate bursts of high-intensity exercise with slower periods. After your two-minute warm up, spend 20 seconds pedaling as hard and fast as you can. Then slow to minimal effort. Repeat this pattern four times, for a total of five minutes of alternating bursts of activity.

Step 3: Rest. Spend one minute pedaling very slowly and breathing deeply to recover. If you're very winded, you can rest completely for one minute.

Step 4: Repeat. After a minute of rest, repeat Step 2, alternating bursts of high-intensity with slower periods.

Step 5: Cool down. This step brings your heart rate down and normalizes respiration-so don't skip it. Pedal slowly for two full minutes to complete your routine. .

And that's it. Just five days of these 15-minute intervals hits the 75-minute mark-a painless 15 minutes at a time.

Pain-free Workouts
Is pain preventing you from working out? Try these simple, natural solutions to exercise discomfort:

• Back braces: inflatable decompression belts relieve pressure and ease back pain.
• Arnica gel: apply topically after training to reduce next-day soreness and stiffness.
• Glucosamine sulfate: as part of a combination joint formula that also includes chondroitin and MSM, glucosamine can reduce inflammation and ease joint pain.
• D-ribose: take twice daily to boost muscle energy and prevent cramping, pain, and stiffness after exercise.
• Capsaicin creams or sprays: alone or in combination with aromatic oils, this derivative of hot peppers can help ease arthritis and muscle pain.
• Hyaluronic acid: take it twice a day on an empty stomach to help ease joint pain and osteoarthritis.