Adjusting for GPS elevation troubles

Posted by Dave on October 18, 2011 | 2 Comments

This weekend, on a whim, I decided to run the Bridges Half Marathon in Chattanooga. It turned out to be a pretty good whim, because I set a PR in the race!

As always, I like to take a look at my GPS record of the race afterwards to see if I might have done something differently to perform even better. But as I have long suspected, when I started to look at the elevation profile of the race, it seemed to completely botch up on bridges.

From a geological perspective, this bridge doesn't exist

Elevation data on the typical GPS trainers that runners use is notoriously bad. You can take a look at the raw GPS data from a run through Kansas and it will look like the Himalayas. To get around the problem, many running websites allow you to correct the elevations by cross-referencing against known databases maintained by NASA and the USGS.

The problem is, those databases don’t account for man-made objects. Run across a bridge, and from NASA’s perspective, you cruised across the river on your hovercraft, 100 feet below. But I hadn’t ever really come up with a clear illustration of the problem.

After uploading my data to the Garmin Connect website, here’s what my elevation profile looked like:

Garmin Connect Elevation Profile

I don’t remember the race being nearly that hilly! The last mile, for example, was completely downhill, and this profile includes a 60-foot climb! Similarly, miles 1, 5, and 7 include major dips that weren’t actually there; I was running across bridges at the time.

I decided to take a closer look at the elevation profile while simultaneously monitoring the satellite map of the course. Based on that observation, I was able to create a modified elevation profile that I think more closely reflects what I really ran:

Are Boston qualifying standards unfair?

Posted by Dave on September 1, 2011 | 8 Comments

I’ve heard it mentioned several times that “women have it easier than men” when qualifying for the Boston Marathon. The argument usually goes something like this: Boston should be accepting the same proportion of talented male runers as female runners. But women get a 30-minute advantage in every age group, when the men’s world record in the marathon is only about 11 and a half minutes faster than the women’s record. It seems like a fairly compelling argument. If men are only 11 minutes faster, why should women get a 30-minute advantage?

As you probably know, the Boston Marathon is one of the few marathons that sets a minimum qualifying standard for most of the runners in the race. The only exceptions are people running for charity or who have affiliations with the sponsors of the race. These standards vary both by gender and age group, the idea being not just that men shouldn’t directly compete with women, but also that 50-year-old men shouldn’t be competing with 28-year-olds for starting spots.

But I’m not sure that the world-record argument makes sense when we’re talking about Boston qualifying standards. For the 2012 race, the fastest qualifying time, 3 hours and 10 minutes, is more than 50 percent slower than the world record. Clearly the typical qualifier doesn’t have much in common with a world-class athlete.

So I decided to do a different calculation. I took a sample of 8 popular marathons run in the past year, and then looked at what portion of men and women qualified for Boston in selected age groups. If women really have an unfair advantage, then a larger percentage of the women competing would qualify, right?

Below is the basic data:

The Basics: Running safely in the dark

Posted by Dave on August 31, 2011 | 8 Comments

The Energizer Night Race (source:

As the days begin to get shorter in the north and the school year wreaks havoc on running schedules, more and more runners are taking to the streets in the dark. I was surprised to realize last week that as the summer wanes, I once again need a headlamp for my regular 6 a.m. run with my local running club.

But as I run in to town on these mornings, I’m equally surprised to see many runners with no illumination at all, and even more who aren’t wearing reflective running gear, despite running along a busy thoroughfare. In the U.S. in 2008, over 4,000 pedestrians were killed in traffic accidents, and nearly half of those accidents occurred at night, despite the fact that there are significantly fewer cars and pedestrians during those hours.

If you run in the dark, you can increase your chances of avoiding an accident by wearing clothing that makes you more visible. Bright-colored clothing can help a little, but reflective running gear and lights improve your odds even more. Think of it this way: Car drivers at night are primarily looking out for other cars and traffic markings. All of these things are illuminated, have reflectors, or both. If you want to be seen, you need to look like the things car drivers are looking for, as this study I wrote up a few years ago for Cognitive Daily attests.

Take a look at the photo above and notice how easy it is to spot the runners, despite the fact that they are dressed in black! They have reflective print on their shirts and bright headlights: The reflectors are what matter, not the color of their outfits. With that in mind, here are some tips for running safely in the dark:

Noakes on starting out in running

Posted by Dave on August 30, 2011 | 9 Comments

Lore of Running

930 pages of science!

This summer I’m reading Tim Noakes’ massive volume Lore of Running, bit by bit, then reporting the critical bits back to you. Last week I covered the ideal running drink: What Noakes believes is the best way to hydrate and fuel up during runs.

Leave it to Tim Noakes to save information for beginning runners until page 258 of his book! While the first part of the book covered the limits of elite runners, in this part he goes back to square one and explains what it takes for a beginner to get started in running.

So what is the best way to get started as a runner? Walking, says Noakes. If you are completely inactive, Noakes doesn’t recommend running at all until week 4 of your training program, and then only for 5 minutes on a single day. Noakes says that stress fractures are the most common injury of beginning runners, and the easiest way to get a stress fracture is to overtrain. Here’s Noakes’ table of the first 20 weeks of a training program designed to ease newbies into running:

Mammals with bigger brains are better “athletes”

Posted by Dave on August 26, 2011 | 1 Comment

ResearchBlogging.orgHow do you measure a non-human animal’s VO2 max? Put it on a treadmill, just like you would with a human. What do you do with that information? If you’re David Raichlen and Adam Gordon, you use it to figure out if there’s any relationship between an animal’s ability as an “endurance athlete” and its brain size.

Perhaps a better question is why you would even imagine there was a relationship.

In fact, there is some reason to believe that brains might be linked to distance-running ability. One of the arguments put forth in Christopher McDougall’s book Born to Run is that humans have superior running ability because they used it to hunt other animals, simply by chasing them until they became exhausted. Humans are the smartest animals with the largest brains (relative to body size), so it’s possible that human intelligence and human running ability are related.

There’s a somewhat less far-fetched rationale for other animals: Aerobic exercise actually releases compounds that stimulate brain cell growth. So perhaps animals that are better at aerobic exercise naturally grow bigger brains. So Raichlen and Gordon found as much data as possible about as many different animals as possible—both VO2 max data and brain size data. In the end, they managed to find data for 29 different mammals including humans. So, is there any correlation between brain size and aerobic fitness? The graph below shows the results:

What’s the minimum (and maximum) exercise to improve health?

Posted by Dave on August 25, 2011 | 11 Comments

ResearchBlogging.orgThe U.S. Department of Health and Human Services currently recommends that adults engage in exercise at least 150 minutes per week. They also say that more exercise is even better, but that also suggests that doing somewhat less than 150 minutes per week might be better than nothing.

If you’re an active runner, you might feel like 30 minutes per day, 5 days per week is the bare minimum you’d consider exercising, but if you’re doing no exercise at all, that much exercise might seem like an insurmountable hurdle. Back in the stone age when I was in my 20s and my kids were babies, I took a couple years off running. When I started back up again, it was very difficult for me to run even 10 minutes at a time. If a doctor had told me I needed to work out 30 minutes a day—especially if I had never exercised before—I might have given up after the first day!

Amazingly, few studies have systematically examined the benefits of exercising less than 150 minutes per week. That’s why a study published last week in Lancet has started to attract some attention. A Taiwanese team led by Chi Pang Wen tracked over 400,000 Taiwanese adults for 8 years, surveying them several times about physical activity levels and their health. Most importantly, their study allowed participants to indicate much lower amounts of exercise: as low as 75 minutes per week. Can just 15 minutes a day, 5 days a week, actually have a measurable impact on health?

What’s the ideal running drink? Noakes weighs in

Posted by Dave on August 23, 2011 | 11 Comments

Lore of Running

930 pages of science!

There’s been a fair amount of discussion of hydration and dehydration on Science-Based Running, but it’s been focused on what to do to prevent serious problems, rather than how to optimize running performance. Let’s assume you’re not going to keel over from heat exhaustion or overhydration in a race. What should you consume before and during the race to maximize your performance?

This summer I’ve been reading Tim Noakes’ encyclopedic volume, Lore of Running and reporting what I’ve found back to you. This week I’m reading his chapter on temperature regulation during exercise. Noakes seems quite convinced that few runners are in danger of dehydration or heat exhaustion during races a half-marathon or longer. Indeed, they are in greater danger of overhydration.

For much of last century, runners were encouraged not to drink at all during races, and the rules often prohibited it. I still occasionally run with people who remember their coaches telling them not to drink during practice because that’s a sign of weakness. Modern elite athletes actually don’t appear to drink much during races either — if hydration is so important, why doesn’t Ryan White carry a CamelBak when he races?

The answer, according to Noakes, is that there is little evidence that runners should force themselves to drink if they’re not thirsty. That said, there’s plenty of evidence that some drinking is very important. The question is, how much, and what should you drink?

One piece of advice I’ve heard given to marathoners is that you should pre-hydrate as much as possible before a race: According to this line of reasoning, the more you pee, the better you’ll do, and make sure you’ve had enough that your urine stream is completely clear.

Noakes disagrees, saying that athletes should have their last drink two hours before race time, and even at that point, only drink enough so that their urine is lightly colored. For races longer than 10K, they should then carry about a half-liter of fluid to the starting line and drink it just before the gun. This is because water takes about two hours to get fully absorbed into your system. Any excess consumed in the meantime will simply be urinated out, along with sodium and other electrolytes your body needs.

A quick running puzzler: Calories burned

Posted by Dave on August 11, 2011 | 10 Comments

I’m still on vacation, but I thought I’d throw out a quick puzzler for you. For the past two days on my run I’ve completed one of the most grueling miles I’ve ever faced; it includes a 25 percent grade for over 2/3 of a mile, for an 870-foot elevation gain. Here’s the elevation profile of the run:

As you can see, it’s quite dramatic. Yet if you look at the record my GPS trainer (a Garmin Forerunner 305) made of the run and saved on Garmin’s website, it actually indicates I burned fewer calories than I did on any other mile:

On the downhill and flat Miles 1 and 2 it says I burned 152 and 171 calories respectively, but on steep uphill Mile 3, it says I only burned 131. Why? I’ll leave this one for you to puzzle out in the comments. One bit of information that might help: I don’t use a heart rate monitor.

The Basics: Running during your vacation

Posted by Dave on August 9, 2011 | 11 Comments

I apologize for the lack of posting this past week, but I have an excuse: I’ve been doing the “research” for this post! I’m in the middle of a two-week vacation in Hawaii, but I’ve also been trying to keep up with my marathon training schedule, which had me slated to do 49 miles last week and 63 this week.

Don't feel too sorry for me

I think I’ve now done enough running in unfamiliar places that I can offer some tips for others who have the same problem: How do you stick to a training regimen while you’re away from home? If you have any additional tips, I encourage you to add them in the comments section below. I’ll try to respond to your comments, but since I’m, you know, on vacation, it might take me a while to get to it.

I’ve found that I can get some excellent runs in while traveling, but it does require a little planning, patience, and flexibility. Here’s how I do it:

  • Take extra gear. You never know when you’ll have access to laundry facilities, so it’s better to be overprepared. Fortunately, most running gear is pretty light, so it doesn’t take a lot of room in your suitcase.
  • If you’re traveling with a group, figure out a time to run that won’t interfere with your group’s plans. I have found that most vacationers don’t like to get up very early, so I set an alarm and finish my run before everyone else’s day has started. If you’re traveling with small children, you could run during their afternoon nap or in the evening after they’ve gone to bed.
  • Don’t worry if you miss a day or two of running. Remember, this is a vacation! If you have to miss a day, try to skip an “easy” day and keep up with your more challenging long/fast runs.
  • Don’t party too hard. This doesn’t mean not drinking at all, but you might consider filling every other glass with water instead of an alcoholic beverage. Or do your late-night carousing the evenings before easier runs.
  • Spend a few minutes before your run to plan out your route. I’ve found the WalkRunJog iPhone app can be helpful for this; it allows you to input your location and planned distance, then gives you nearby routes other runners have used. One problem with the app, however, is that it seems to be used primarily by other travelers who are as clueless as you are about the local running conditions. In a trip to San Francisco last year, for example, many routes went straight up or down extremely steep hills, or along streets with tons of stoplights. (I’ve added some more tips about planning your route to the end of the article.)
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Do world-class sprinters really move their legs no faster than ordinary runners?

Posted by Dave on July 28, 2011 | 29 Comments

ResearchBlogging.orgThe speeds attained by world-class sprinters like Usain Bolt are simply unfathomable to me. During today’s workout, I ran at nearly top speed for a set of 400-meter repetitions: About a 6-minute-mile pace, or 10 miles per hour. Sure, I could probably hit 15 mph over 50 meters or so, but that would be about it. Bolt, on the other hand, attained a pace of .82 seconds per 10 meters during his world-record sprint: 27.3 miles per hour, or nearly twice as fast as I can run.

But this article, which has been making the rounds lately, suggests that despite Bolt’s prodigious speed, his legs are moving no faster than my own:

When Bolt established the current 100-meter world record in the 2009 world championships, running it in 9.58 seconds, he did so by moving his legs at virtually the same pace as his competitors. In fact, if you or I were to compete against Bolt, our legs would turn over at essentially the same rate as his.

How could that be? Don’t Bolt’s feet need to contact the ground during his run? And isn’t the ground moving past his feet at nearly twice the rate it does when I’m running at top speed?

The Yahoo Sports article I quote here mentions a 2000 study led by Peter Weyand, so I decided to look up the original study and see if Yahoo is getting it right. Indeed, the study’s title suggests that the Yahoo article is correct: “Faster top running speeds are achieved with greater ground forces not more rapid leg movements.” But it still didn’t make sense to me that the fastest sprinters move their legs no faster than ordinary runners, so I gave the article a close read. What did I find?


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