High-intensity workouts provide twice the cardio benefit while cutting your workout time in half. But if that runner's high is accompanied by painful knees, or those squats are leading to sore joints rather than sore muscles, it's time to try a more knee-friendly workout. Taking breaks with workouts that are kinder to your knees may allow you to tackle your other workouts with more power after a couple of rest days.
OK, so a 50-mile mountain terrain bike ride might not be so friendly to your knees, but a recumbent bike can do the trick. A study published in a 2004 issue of "Biomedical Sciences Instrumentation" found that cycling in the recumbent position could reduce knee loads, making it safer for your sore joints. The smooth movements of the pedals paired with the position of the leg means you'll be pedaling without pain.
Ah, water -- it's the perfect balance of natural resistance and shock absorption, making it the ideal way to save your knees while getting in a workout. Whether you swim a few laps at the gym or head to your local YMCA for a water aerobics class, you'll still burn nearly 500 calories per hour by donning your swimsuit and diving on in. Adding water weights or alternating periods of fast swimming with intervals of slower, distance swimming can also help you burn more calories, all without lacing up your runners.
If you want to burn calories and get the therapeutic-like satisfaction of a run, check out the elliptical machine. It offers the same benefits as running without the harsh impact of your shoes striking the sidewalk. If you want to amp up the difficulty on the elliptical, try increasing the resistance level or cranking up the speed for one or two minutes and then slowing back down to a comfortable speed, alternating between the two for a stellar, knee-friendly interval workout.
While you might be used to pumping iron for strength training, plyometrics and leg-centric workout machines can place strain on your painful knees. Instead, try strength training workouts that offer slow, fluid movement to protect your knees but still score a solid workout. MayoClinic.com gives its stamp of approval on tai chi for every fitness level, particularly those with joint issues, while yoga and Pilates can offer balance, strength and flexibility training by focusing on form and slow, precise movements to give your knees a break. Just let the instructor know that you're giving your knees some TLC -- she can show you various poses, exercises and modifiers to protect your joints while still providing a challenging workout.
Kay Ireland specializes in health, fitness and lifestyle topics. She is a support worker in the neonatal intensive care and antepartum units of her local hospital and recently became a certified group fitness instructor.