http://www.active.com/story.cfm?story_id=12223

By Matt Russ
For Active.com
August 16, 2005

The shoes we run in today are great for reducing impact. There are a
myriad of devices, gels, air channels, etc., designed to lessen the
compressive loads on the joints.

One drawback, however, is that if you do most of your running on even,
paved surfaces the lower leg muscles and joints don't have to work as
hard to stabilize. Joint stability and integrity are crucial for
injury prevention. That's where trail running comes in.

Running over uneven and varied surfaces makes the muscles of the lower
leg work especially hard; think specific strength training for the
lower leg muscles. I recently noticed how sore my lower legs were
after a competing in an off-road multi-sport event. The tendons,
ligaments and muscles all get stronger in response to this type of stress.

Best time is in base

There are a few considerations when integrating trail running into
your training plan. Unless you run in off-road events, the best time
to incorporate trail running into your plan is in base.

As with any new type of training stress, it's important to implement
it gradually. You may want to start off with one workout per week of
limited mileage, and steadily increase the duration.

Off-road surfaces vary from crushed gravel, sand, grass, single-track
hiking trails, to rough back-country trails. The more varied the
terrain, the more your lower legs and body will be stressed. On
extremely rough and elevated terrain, hiking may be just as effective
(and safer) than running. You'll likely enter your aerobic base zones
in this type of terrain without having to run.

Use trail shoes

Trail shoes offer more support and traction, but much less cushioning.
Trail shoes vary from running shoes with a more aggressive tread, all
the way up to hiking shoes which may not applicable for running.

Make sure you consult with a salesperson to get the right shoe for
your type of training. I don't recommend doing any road running in a
trail shoe, but you can take your running shoes off road if the
surface is relatively stable, such as crushed gravel.

Trail running works both the lower legs and all the muscles associated
with running, including lateral knee stability, and will help develop
coordination. You can continue to incorporate trail running throughout
the season for strength maintenance. Trail running adds variety to
your training, with better scenery!

Matt Russ (has coached and trained athletes around the country and
internationally. He currently holds licenses by USAT, USATF, and is an
Expert level USAC coach. Matt has coached athletes for CTS (Carmichael
Training Systems), is an Ultrafit Associate. Visit
www.thesportfactory.com for more information or e-mail him at
info@....