What Are METs and How Can They Help Improve Your Fitness?

Many of us, especially around New Year's, resolve to become more fit. However, going to the gym doesn't help much if you don't know what you're doing. Medical studies suggest improving your METs level may save your life. The following explains what METs are, how they measure your current fitness, and how to increase your METs level.

METs Defined

METs is short for "Metabolic Equivalents" with one MET equal to 3.5 milliliter oxygen per kg body weight per minute. Put simply, METs measure how hard your body is working. The harder your body works, the more oxygen it burns to release the energy it needs to work, the higher the METs level. At complete rest, on average, your METs level will be 1.0 or 1 MET.

METs During Activity

The University of Medicine and Dentistry of NJ provides useful tables of METs levels for a variety of activities, both day-to-day and fitness.

Some interesting examples:

- Studying - 1.8 METs.

- Walking a dog - 2.5 METs.

- Walking at 3 mph - 3.5 METs.

- Shoveling - 6 METs.

- Hiking - about 7 METs.

- Swimming at moderate speed - about 8 METs.

- Running at 6 mph - 10 METs.

- Running at 10 mph - 16 METs.

- Interestingly, weight-lifting has a value of about 6 METs, lower than a fast jog.

What Your METs Level Tells You

Dr. Howard LeWine, chief editor of Internet publishing, Harvard Health Publications, and clinical instructor of medicine at Harvard Medical School and Brigham and Women's Hospital says¹: "average healthy but non-athletic middle-aged men and women have peak exercise capacities in the range of 8 to 10 METs; marathon runners can have values as high as 18 to 24."

A rule of thumb he provides sets a target METs level (here's a bit of math, but not too hard): for men subtract 0.11 times your age in years from 14.7. For women, subtract 0.13 times your age from the same 14.7 METS. Thus a 40 year old woman would have a target METs level of 9.5 (= 14.7 - 0.13 x 40).

Personal trainers recommend you also check your pulse rate and not exceed a rate given by subtracting your age from 220. For example, if you're 45 years old, your maximum pulse should not exceed 175 beats per minute. Many modern exercise machines (treadmills, elliptical trainers, recumbent bikes, etc.) display your METs level as well as your pulse.

How You Can Improve Your Fitness using METs

Before starting a new fitness program consult your doctor to make sure you can follow the new fitness regime safely. Personal trainers usually start with an assessment of your current fitness level. Get on a treadmill and start at a brisk walk or slow jog (depending on your health and fitness level) to warm up. Within what your doctor permits, speed up until you feel close to the fastest pace you can maintain for more than a minute. Look at the METs level and make note of it.

You can expect the best results by running on a treadmill (or exercising on an elliptical trainer) almost every day for 15-30 minutes. Each time warm up well before ramping up to a challenging METs level. One recommended method is called "interval training."

The interval method has you boost your speed (and METs) to a point you feel challenging and maintain that pace for 45 - 60 seconds, followed by 90 - 120 seconds at lower METs level to catch your breath. Repeat this cycle for as long as you can, starting at 10 minutes, and working up to 20 or 30 minutes over time.

Once you've reached your goal for the day, slow down to a brisk walk and continue until your pulse slows down by about a third. After this cool-down, carry out stretching exercises to improve your flexibility.

What METs Say About Your Health

Dr. LeWine reports¹ that according to a study published in 2005 in the New England Journal of Medicine "Women whose exercise capacity [in METs] at the start of the study in 1992 was less than 85% of the predicted value for their age were twice as likely to have died over the next eight years compared with those who achieved 85% or better."

Bottom Line About METs

While the definition of METs sounds esoteric, it is a very important measure of your fitness. Calculate your target METs rate using the guideline above and test yourself (after checking with your doctor). You may find your fitness is too low for your age and gender. If it is, exercise regularly to improve your METs capacity. It may save your life.

¹Aetna Intelihealth (1/20/2006)