I'm often asked how much running is enough. The answer depends upon what kind of runner asks the question.

Here are descriptions of the various types of runners:

Wellness runners.

We all know that a routine moderate exercise keeps

our hearts healthy. Physicians advise exercise periods of 20 minutes three times per week at 70 to 85 percent of maximal heart rate to reap the benefits of running.

Including warm-up and cool down, that translates into about a 30 minutes of running or brisk walking.

Most wellness runners can judge pace by perceived effort. Runners should aim for a pace that breaks a sweat but one at which they can talk comfortably.

If you can talk but not sing, you are approaching the upper limits of the aerobic zone.

Fitness runners. Fitness runners go beyond the minimum. They might run for weight control or to complete various race distances.

Long, slow distance works best for weight loss. Calculate 3,200 calories for each pound of body weight loss at a burn of 80-100 calories per mile Men and larger folks will burn calories at a faster rate.

Fitness runners aiming to complete a particular race distance can calculate their collapse point using a formula cited by Ken Young in "1974 Marathon Handbook."

First, determine average daily mileage based on three consecutive months. Then, multiply by three to determine the point at which performance will drop dramatically, the infamous "hitting the wall."

Although marathoners are familiar with the wall, runners at any distance can reach a collapse point. Runners can get by on less mileage and stretch the outer limits of distance by running slower or by taking walk breaks during long runs or races.

Fitness runners can run as few as three or as many as seven days a week, depending on mileage goals. Before attempting a particular race distance, especially longer ones, runners should complete two or three runs of at least two-thirds of the race distance.

Performance runners

. This type is interested not only in completing a distance, but completing it with speed.

Performance runners typically run five to seven days a week with mileage of 25 to 50 miles a week for 5K training, 50 to 70 miles weekly for races up to marathon length.

Weekly long runs should be 10 to 18 miles with marathon trainers throwing in a 20- to 23-mile run every two or three weeks.

Performance runners also include running at a faster pace than aerobic training, typically short, steady runs at about 80 percent of maximal heart rate and repeat intervals of above 90 percent.

Runners who wish to change levels, from wellness to fitness or fitness to performance, should add mileage slowly.

First, add running days until you are running at least five days a week. Then, lengthen one run per week, boosting mileage by no more than 10 percent. Finally, add miles to the other running days until you achieve your mileage goal.

Top it off by running at least three weeks at the new mileage level before adding speedwork. Decrease mileage by 10 to 20 percent while gradually boosting the speed.

Saturday, 9 a.m.: Up-N-Running Fun Run-Walk, Valencia. Meet for coffee and run or walk your choice of distance. 724-898-2525March 27, 8:30 a.m.: Just a Short Run, 30K, 30K relay, half marathon, 5K, North Park. Challenging out-and-back 5K, longer races loop around North Park Lake. 412-490-6911 or www.pittsburghraces.comMarch 27, 10 a.m.: Fool's Run 10K and 3-mile walk, Indiana, Pa. showers available. 724-349-1354, 724-349-0501 after 6 p.m.

Spring Thaw 10-Mile, March 6: Jerry Pullins, 1st Overall M, 55:35; Herb Cratty, 2nd Overall M, 57:47; Jesse Bender, 3rd Overall M, 58:10; Sharyl Relic, 2nd Overall W, 1:13:17; Mark Hunkele, 1st 30-34 M, 59:46; Leslie Kramer, 1st 20-29 W, 1:15:34; Leeanne Beiber, 2nd 20-29 W, 1:16:11; Karl Zellars, 2nd 19 and Under M, 1:16:28; Sandy Onofray, 1st 45-49 W, 1:19:04; Barbara Fellman, 1st 50-54 W, 1:20:35; Lori Piedimonte, 1st 40-45 W, 1:22:48; Lou Lodovico, 1st 70 and over M, 1:25:16Sherry Mason, 2nd 50-54 W, 1:27:33; Eric Fowler, 1:16:06; John Millea, 1:11:52; Mitch Radella, 1:14:01; Ken Zellars, 1:16:49; John Limbacher, 1:17:12; David Graham, 1:19:56; Bruce Barnes, 1:20:24; Bob Crawford, 1:21:45; Bob Miller, 1:23:13; Ron Hartle, 1:23:29; Matt Drohan, 1:25:18; Theresa Cardone, 1:27:01; Mark Ray, 1:27:45; Charles Patton, 1:28:30; Jack Cully, 1:30:09; Frank Piedimonte, 1:31:11; David Guo, 1:35:16; John O'Donnell, 1:35:28; Terry Reeher, 1:38:05; Robb Fort, 1:43:32; Carolyn Sabo, 1:46:56; Lynn Brehm, 1:48:31; Dana Hogue, 1:51:55; Kim Kenetz, 2:15:54Spring Thaw 20 Mile, March 6: Leslie Kramer, 1st Overall W, 2:33:30; Leeanne Beiber, 2nd Overall W, 2:33:51; Mitch Radella, 2:32:31; Tim Weil, 2:32:27; Mark Ray, 3:21:23Send comments and suggestions to: 435 Cherry Valley Road, Saxonburg, PA 16056. Phone or fax: 724-352-4395. Email: bigp@penn.com