Boosting Your Fuel Economy

Another result presented at the Endurance Research Conference in Kent, this one on strength training to improve running economy.First, some background. Running economy is like the fuel efficiency of a car: it tells you how much fuel a given runner needs to run at a given speed. The more efficient you are, the faster you should be able to race. A question that remains hotly debated, however, is how to improve running economy.

One of the most famous examples is Paula Radcliffe. Andy Jones, a physiologist at the University of Exeter who worked with her over many years, has published data showing that Radcliffe’s VO2 max hardly changed over the decade-plus of her ascent to world-class, while her running economy steadily improved.

How did she do it? One theory is that the best way to improve economy is simply to run a lot (which Radcliffe certainly did during those years). Jones was coauthor on another study a few years ago that measured running economy in beginning runners before and after a 10-week training program. With no specific instruction and no exercise other than running, economy improved by about eight percent, and the improvements were correlated with subtle changes in running stride (e.g. a less extended knee at toe-off). With practice, your body automatically seeks the most efficient way to move.

But improving economy gets trickier with experienced runners. Of the ideas out there, the one with the best evidence is probably strength training. Over the years, various forms of strength training, often emphasising heavy weights or explosive movements to maximise neuromuscular recruitment, have been shown to improve running economy. None of these studies has provided a definitive smoking gun, but together they’re at least suggestive.

The latest result comes from a group at the University of Verona in Italy, led by Federico Schena. They divided 29 well-trained recreational runners (average age 44) into three groups for eight weeks of training three times a week:

  • One group did “low intensity” running, primarily between 70 percent and 105 percent of tempo pace.
  • The second group did “high intensity” running, between 95 percent and 150 percent of tempo pace, with the total training load (time x intensity) equalised between the two groups.
  • The third group did the same training as the low intensity group, but added one weekly session using the “YoYo Leg Press,” a leg press device that promises to resist eccentric muscle contractions. Each workout was just 4 sets of 7 reps.

The results were pretty straightforward: no change in running economy in the first two groups, and ~five percent improvement in running economy in the strength training group (from 4.5 to 4.3 Joules/meter, p<0.05). Maximal leg-press strength also increased in the strength-training group (not surprisingly), but muscle mass measured by DXA didn’t change, suggesting the improvements were neuromuscular.

Again, this is yet another small study, but it adds to a pattern of results suggesting that strength training might be a means of improving running economy. A couple of points to note:

  • The selling point of the YoYo press is that it targets eccentric contraction; but it also involves concentric contraction, so there’s no way of knowing whether the improvements have anything to do with eccentric contraction. To make that claim, you’d need to compare the YoYo press with a conventional leg press. For now, I think all we can conclude is that strength training helps.
  • The runners in this study were mostly masters runners, with an average age of 44. There’s a little bit of evidence that, in cyclists at least, older athletes get a bigger boost from strength training than younger ones, presumably because age-related decline means that older athletes are typically weaker to begin with. Something to keep in mind as motivation if you’re past your mid-30s.

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