Jeff in Portland, Ore., writes: “Arrgghh . . . And just when I thought my 3 to 4 times per week of hitting the gym was an extraordinary feat. The recommendations from this study seem to support a growing consensus among researchers that ‘more is better’ when it comes to exercise.”

The study Jeff refers to is the latest finding to emerge from Lawrence Berkeley National Laboratory scientist Paul Williams’ marathon National Runner’s Health Study. Begun in 1991, the study has looked at more than 120,000 runners to examine everything from the effects of alcohol on running to the “unequal benefits of running.” The latest to emerge from the NRHS: the more you run, the less likely you are to have such health problems as heart attacks, strokes, vision problems or arthritis.

Williams’ latest study found that the health benefits of running continue rising for people who run about 50 miles a week. (He suspects benefits rise even more past 50 miles, but there weren’t enough ultra-distance runners in the study to draw a conclusion.) His findings represent 20 years following the same group of runners.

Williams, who reportedly runs 35 miles a week, has been critical of federal recommendations people should get at least 30 minutes of exercise a day, or 150 minutes a week. “Up until recently,” he told the San Francisco Chronicle, “the exercise research has pretty much focused on the couch potatoes. We’ve become fixated on how to get fat people to lose weight. But we shouldn’t be pitching the weight loss and exercise thing only to the obese, sedentary people.”

You won’t get an argument from health officials that 30 minutes a day is indeed a bare minimum, that people really need more (60 minutes is preferable, they say). They’re desperate to encourage any kind of movement in a country whose collective waistline has been expanding for the past few decades. Thirty minutes is better than nothing, they say, and nothing is what they fear they’ll see if they suggest something on the order of running 7 1/2 miles a day.

So, are Jeff’s four trips a week to the gym in vain? Missing from Williams’ report was information on injuries suffered by runners who are racking up 50 miles a week or more. Running, as any runner will tell you, can be hard on the body. Some estimate that as many as 85 percent of runners will suffer an injury in any given year. Even Runner’s World magazine says more than half of runners will get injured. Which is why running programs such as the Galloway program, which touts an injury-free, walk/run approach to ramping up to the big miles are so popular (more than 200,000 runners and walkers have gone through the Galloway program, which focuses on preparing runners for marathons and half marathons).
The situation with cycling is similar. It wasn’t long ago that hard core rec riders preparing for a race talked about piling up “junk” miles — miles pedaled just for the sake of logging miles. Today, training regimens focus on “smart” miles, or occasional days of long mileage interspersed with shorter, interval training days and two days of rest per week. One popular program even suggests riding hard for three weeks, then taking a week off.

You won’t get much debate over the fact that 30 minutes of exercise a day is the bare minimum. But 50 miles of body-jarring running a week? That brings up another currently popular school of thought on exercise: Mix up your workouts.  Do the same thing over and over and your body gets used to it, the benefits diminish. For most of us, logging 50 miles a week doesn’t leave much time for cross training. Further clouding the issue: an emerging cottage industry of 4-minute-a-day workouts.

4 minutes? 30? 60? Two marathons a week?

In short, Jeff, don’t stop going to the gym. Somewhere, there’s a study that says what you’re doing is just right.