Fitness for Survival

Research Blogging / by Dave Munger /

Regular exercise can help us live longer. But what exercises are the most effective, and how much do we need? New research suggests that more is better, and variety is best.

Credit: Flickr user Hamed Saber

It’s 7 o’clock in the morning on a Sunday, and five of us are ready to start our weekly long-distance run. I joined this group about 8 months ago, and they’ve inspired me to train for my first-ever marathon. While I’ve improved steadily since I joined the group, today, as usual, I can barely keep up. I’m planning on running 10 miles, but Rodney has already run six and will probably only do another seven or eight. Tina wants to run six, and Todd and Chad would like to do at least ten, preferably more. Chad leads us on a route he says will be “about 7 miles”—then anyone who wants to can add on a few extra miles at the end.

My GPS trainer beeps, indicating we’ve finished mile 1. The pace seems fast for me: 8 minutes, 15 seconds. I may need to slow down a bit. Mile 2 is even faster: 7:44. Will I be able to maintain this pace for 10 miles? If so, it will be my personal best: The fastest I’ve run that distance recently was more like 8:30 per mile. The miles tick away: 7:53, 7:51, 8:02… Maybe I’ll actually be able to keep this up! I’m definitely the slowest in the group, which kindly stops to wait for me at the tops of big hills.

But for the final 2 miles, I manage to stay with Chad and Tina, and we come to a stop at our meeting place in front of a local drug store, having averaged 8:07 for 9 miles. Elatedly I realize this is the fastest I’ve run in years! Tina’s pleased too—she’s just back from an extended trip to Europe where she hardly exercised at all, and she’s amazed she can still put in that kind of distance, but a little disappointed at her “slow” pace. Then Chad smiles and asks who’s up for two more miles. I grit my teeth and head back out on the road with Chad and Todd.

These long, steady runs are by far my favorite fitness activity. I can’t stand lifting weights, and I barely tolerate “interval” training—a series of short, fast runs separated by even shorter breaks, both recommended by most coaches to improve a distance-runner’s speed. Am I doing my body a disservice by focusing almost entirely on longer runs? And while I enjoy running, shouldn’t I be doing other types of fitness activities if I really want to improve my health and extend my life?

Physician Bill Yates asked some of the same questions on his blog last month, and a team led by Lars Nybo has come up with with a partial answer, in research published in this month’s issue of Medicine & Science in Sports & Exercise. The researchers divided 36 men into three groups, which did one of three types of intense exercise for 12 weeks: Steady running, interval running, or weight training. The steady runners ran one hour per day. Interval runners did a five-minute warm-up, followed by five, two-minute intervals (with rests in between). The strength trainers lifted weights for an hour, focusing on their legs. Each group worked out three times per week.

The researchers found improvements in all three groups—but in different measures of fitness. Interval trainers improved maximum oxygen uptake, the body’s capacity to use oxygen during exercise, while steady runners and weight-trainers didn’t. Steady runners improved their ratio of HDL (“good” cholesterol) to total cholesterol, while the others didn’t. Both running groups improved their blood glucose levels. Steady runners lost weight and decreased body-fat percentage, while strength trainers gained weight and increased muscle mass.

Aside from gaining weight in the case of strength training, all of that sounds pretty good to me. As Yates points out, the ideal fitness regimen probably involves all three activities—and possibly others as well!

But how much should you exercise? Before I started marathon training, I exercised about four hours a week. Now I’m up to around six hours, and that amount will probably increase as I get closer to the event. Is that enough? It’s hard to say, says obesity expert Yoni Freedhoff. In May, Freedhoff blogged about new guidelines for exercise advocated by the Canadian Society for Exercise Physiology: 60 minutes a day for children, and 90 to 150 minutes per week for adults. By those standards, I’m doing plenty. But Freedhoff isn’t sure the guidelines make much sense. If I wasn’t getting any exercise at all, 90 minutes per week might seem unattainable. Could I handle extended workouts if I was completely out of shape? Freedhoff cites a 1995 study showing that women who were encouraged to exercise 10 minutes at a time actually exercised more than women who were asked to work out in 40-minute chunks.

Freedhoff argues that the worldwide obesity epidemic isn’t happening because people are getting lazy; instead, the world has changed around us. A hundred years ago, it was almost impossible to avoid physical exertion: Few people had cars, and simply getting through life required a lot of effort. Now we not only have cars, we also have mechanical devices to assist with nearly every possible task, from washing dishes to opening the garage door to getting our daily news at a click of a button instead of a three-block walk to the newsstand. Exercise is now something we must artificially add in to our lives, not something we can’t avoid. There shouldn’t be a recommended number of minutes, Freedhoff says; instead we should use any method we can to get as much exercise in as possible.

So what’s the best way to motivate oneself to exercise? Casual observation of the runners I see on my daily workouts suggests that listening to music is a huge key. Does music actually help us to exercise harder? The psychology student who blogs as “Rift” reviewed several studies of the effect of music on exercise, and found that, while the effects are relatively small, fast-tempo music does seem to help us exercise harder. In the most persuasive study, researchers played music as student volunteers rode exercise bikes. As the speed of the music increased (unknown to the students), their pace also increased—although it’s unclear if these results rose to the level of statistical significance.

I wear an iPod when I run by myself, but usually I listen to podcasts rather than music; I find I get bored relatively quickly otherwise. For me, however, the biggest motivator is knowing that my friends will be out running. On Sunday, that’s what carried me through those last three miles. And yes, as I blogged a few years back, there’s research showing that even seemingly trivial levels of verbal encouragement help athletes perform better. Freedhoff points out that people often do well while in controlled research on fitness interventions, but once they are no longer motivated by participating in a research study, they revert to their old ways. Perhaps the most successful fitness programs in the future will be those that pair up compatible workout partners for the long run.

Dave Munger is editor of ResearchBlogging.org, where you can find thousands of blog posts on this and myriad other topics. Each week, he writes about recent posts on peer-reviewed research from across the blogosphere. See previous Research Blogging columns »

Originally published October 6, 2010

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