Some interesting new research is out on the effects of running. Some of the findings will make you want to dig your waffle trainers out of the closet. Other findings may explain a thing — or ache — or two.

For instance, if you thought Forest Gump was nuts, in fact, he may have been on to something with his cross-country jaunts. A study of 44 runners taking part in the 4,500-kilometer 2009 TransEurope-FootRace (in case you’ve forgotten, the 2009 TEFR began in southern Italy on April 19, 2009, and ended in Norway on June 21 of that year) explains some phenomena that may survive even accomplished runners. The runners who agreed to participate in the study all had their blood, urine and biometric data (whole-body volume, body fat, visceral fat, abdominal subcutaneous adipose tissue and fat and skeletal muscle of the lower extremities) collected daily. Some also slid into an MRI (“the gold standard for the evaluation of the musculoskeletal system of the runner,” according to the study) every three or four days. From all this poking and prodding researchers made some general findings:

• On average, the runners lost 5.4 percent of their body volume over the course of the 64-day race.
• They lost 50 percent of their body fat over the course of the race, 40 percent of which dropped during the first 2,000K.
• Muscle volume in their leg declined by 7 percent.

The latter was one of the negative findings: With prolonged, extended use the runners’ leg muscles actually degenerated because of the “immense energy consumption.”

On the plus side was that initial loss of fat, which occurred earlier in the process than previously thought. Even more significant was the fact that of the initial fat lost, much of it was visceral fat, the most dangerous type of fat, contributing to cardiovascular disease.

Also on the good-news front: Some leg injuries appear fine to run through. Any type of “intermuscular inflammation,” for instance, will not cause additional tissue damage. You need to be more careful with overuse injuries (e.g. joint inflammation), though additional damage isn’t assured if you continue to run. Running through pain, in other words, is sometimes OK (though be sure you’re clear on which kind of pain it is).

The study, authored by Dr. Uwe Schutz, a specialist in orthopedics and trauma surgery in the Department of Diagnostic and Interventional Radiology at Germany’s University Hospital of Ulm, was presented at the annual meeting of the Radiological Society of North America. Read more here.

Running also may help you outdistance the aging process, for as the latest issue of Deutsches Arzteblatt International, on newsstands now, reports, bad lifestyle habits and lack of exercise have more impact on our health than aging.

A study of marathon and half marathon runners age 50 to 69 found they tend to live four years longer than their non-running counterparts. (They’re often also faster than their younger running counterparts.) The study is based on the fact that distance runners tend not to be obese, don’t smoke and are physically active. More encouraging: You needn’t be a life-long runner to benefit. One in four of the runners studied had taken up the pursuit within the past five years.

More info here.

A caveat to these findings comes from another study presented at that recent get-together of the Radiological Society of North America. Running and other high-impact activities may lead to a higher risk of developing osteoarthritis. Osteoarthritis, a degenerative joint disease that causes pain, swelling and stiffness, is the most common form of arthritis, according to the National Institute of Arthritis and Musculoskeletal and Skin Diseases. It afflicts about 27 million Americans over age 25.

A study of 99 women and 66 men between 45 and 55 found that moderate to strenuous exercise accelerated cartilage degeneration, putting participants at greater risk for developing osteoarthritis. Other activities that could cause problems: anything involving frequent knee bending, climbing at least 10 flights of stairs a day, lifting anything heavier than 25 pounds, squatting or kneeling for more than 30 minutes a day. Cardiovascular activities that are a safer bet: walking, swimming, the elliptical trainer.

More on this study here.