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Calculate grade (Read 2573 times)

Trent


Good Bad & The Monkey

    This thread breaks my heart. I miss va. Undecided
    eric :)


      This thread breaks my heart. I miss va. Undecided
      ditto


      Giant Flaming Dork

        This has been bugging me for a while. I think I got it and it IS calculus, albeit simple calculus. You need to calculate the difficulty based on the area under the curves, using different constants for uphill and downhill, of course. The easy solution is worked out on the 3 hills vs. 1 hill problem. Empirically we know the "one hill" is more difficult, but how do you prove it? The area under the one hill is 1/2 * b * h. If we assume 300ft climb and 3 mile race, b = 3mi and h=300ft and is 450 "foot-miles". The area under the three triangles is 3 * 1/2b * h, where b= 1mi and h=100 and the area under that is 150 "foot-miles". So relatively, the "one hill" case is three times harder than the "three hill" case. Makes sense?

        http://xkcd.com/621/

        gmaclin


          Hi everyone: I have been thinking about this subject for several years now and started putting a major amount of time into it during the last 6 months (Trent has been involved in some of the discussions I started over on the RW forum). I came across this particular discussion in one of my many searches on the Internet for more information and thought I would contribute some of what I've found/developed. I became interested in this subject when I ran across this web site hosted by the Association of Road Racing Statisticians (AARS): http://www.arrs.net At that time, I had qualified for Boston for the first time and was trying to get more information on how hard the Boston course was. I was particularly interested in this page at the AARS site that showed the average "race time bias" for elite atheletes at a list of different marathons around the world: http://www.arrs.net/TB_Mara.htm I had always heard how difficult the Boston course was, but was amazed to see that the AARS site showed that on average Boston was only 1.8 seconds slower than Chicago for elite athletes! When I actually ran Boston, I found that as long as you trained and paced properly for it, it wasn't nearly as hard as I was led to believe by other runners (I qualified in Chicago with a time of 3:35:22 and completed my first Boston with a time of 3:36:26). That exerience led me to create a "Boston Marathon Predicted Times" spreadsheet that used the data from the AARS site: http://www.box.net/public/sxmjutz7af The problem with the above spreadsheet was that it was based on data from elite athletes and it included a lot of marathons that "normal" runners from the U.S. would probably never run. So, I started looking to see if there was a way to input all the information about a marathon course (uphills, downhills, altitude, number of turns, running surface, etc.) and have a "formula" that would take all of these factors into account and produce a "difficulty factor" for each marathon course. First, I tried to find out if anyone had done any serious research into the subject and ran across this article from Running Times: http://runningtimes.com/Article.aspx?ArticleID=10507 This article mentions a researcher named Mervyn Davies who did extensive studies in the early 1980's of the effect of hills on the energy expenditure of runners. (Tim Noakes quotes Davies' research in his book the "Lore of Running".) Mervyn Davies' basic forumla for how much energy runners expend on hills is as follows: Every 1% of upgrade slows your pace 3.3% Every 1% of downgrade speeds your pace by 1.8% After playing around with this formula on elevation data for various marathons, I felt it needed to be "tweaked" a little for the much longer distance. Here is what I came up with: Miles 1 - 16: Every 1% of upgrade slows your pace 3.3% Every 1% of downgrade speeds your pace by 1.8% Miles 16 - 21: Every 1% of upgrade slows your pace 3.8% Every 1% of downgrade speeds your pace by 1.8% Miles 21 - 26.2: Every 1% of upgrade slows your pace 4.3% Every 1% of downgrade speeds your pace by 1.8% (The logic behind this is that uphills located late in the race will be more difficult than uphills located closer to the start.) I built a spreadsheet for analyzing the altitude data for any marathon course that takes into account the following: Uphills/downhills (using the above forumulas) Altitude Number/type of turns on the course Running surface (smooth, rough, very rough, extreme) I takes all of this into account and spits out a difficulty factor for the course. I used this to analyse a number of different marathon courses and collected all of the data into the following spreadsheet: http://www.box.net/shared/pny45dzc4k Be warned: This spreadsheet doesn't necessarily agree with the opinions of runners who have run some of these courses and tends to upset some of them when it doesn't agree with their own perceptions. I think a lot of marathon courses have reputations that are not necessarily correct (e.g. "Boston is extremely difficult") and I think it would be great if we had a tool that could accurately evaluate a marathon course and allow us to objectively compare different courses around the country. By the way, I've had people say that this entire excercise is useless unless I take weather, body weight, and a list of other similar factors into account. I disagree. The factors that I don't include are impossible to predict or control. For example, I started down the path of using average race day temperatures and discovered that almost every race I researched was scheduled for a time of year when average temperatures fell into the "ideal" range (45 - 60 degrees). At almost any of these races you could have ideal weather or extremely hot weather (e.g. Chicago '07). For those reasons, I chose to use only the attributes of a marathon course that are completely predictable and constant. Otherwise, I think it would be impossible to accurately compare them. One last comment: The spreadsheet I use for analyzing marathon course info has a huge dependency on the accuracy of the elevation data I feed into it, so I've been downloading data from multiple sources so I can compare them. I have not found a way to create a map of a course at this site (RunningAHEAD) and then download the elevation data in a file format such as .CSV, .GPX, etc. Is there a way to do that here? This is still a "work in progress", so ideas and feedback would be welcome. Greg
          Trent


          Good Bad & The Monkey

            Greg!! Welcome to RA! Big grin Folks, Greg has created a whole series of awesome cool elevation profiles and marathon grading algorithms. He and I see different utilities in elevation profiles and how they should look, but it is all great stuff. Greg, we had an interesting discussion about them, with some folks preferring your view and others preferring mine: http://runningahead.com/forums/post/238bed3953a0435a8de51d584b65a8e7#focus. It is interesting how different people use elevation profiles so differently. Good stuff! There is not currently a GPX export, although that is coming. If you know how to implement a regular expression, you can parse out XML from the page source though; just look for the polyline.
              Greg- Excellent Work. I notice that the list is pretty small so far, and as you make it more cumulative I think youll discover that you will need to take weather into account as you complete the list. For example, the Los Angeles Marathon has broken 80+ degrees 3 of the last 5 years. The Honolulu and Maui marathons are usually ridiculously muggy. These factors are typical of these races and cannot be ignored. I agree with your assessment about your present list, that the average weather falls into the ideal range and TCM or Chicago 07 are an anomoly. I think you should consider simply having two buckets as you add more races: one for marathons in the ideal temp range, and another for hot weather marathons.
              gmaclin


                Hi Trent! Wow, that was a quick response - you must "live" here! By the way Trent, the main reason behind the scaling factors I use for my elevation charts is so I can use them in my pacing spreadsheets. Here is an example of one of them (for NYC): http://www.box.net/shared/ec0vyk6iah When you open this spreadsheet, take a look at the "Elev. Chart" tab and you will see that I take my elevation charts and split them up into 5 pieces and arange them on the page so I can include other information with the elevation chart. Greg
                Trent


                Good Bad & The Monkey

                  Heh. I do live here. Wink
                  gmaclin


                    ...I think youll discover that you will need to take weather into account as you complete the list. For example, the Los Angeles Marathon has broken 80+ degrees 3 of the last 5 years. The Honolulu and Maui marathons are usually ridiculously muggy. These factors are typical of these races and cannot be ignored...
                    Good point Ryan - you're right. I will take another look at that and see what makes sense. Trent: Do you have any idea how soon the GPX export will be implemented? I don't want to spend a lot of time figuring out how to manipulate the data contained in the page source if that feature will be coming soon. It would be great if this site also allowed course data to be exported directly into .CSV format as well. That would make it even easier for people to manipulate the data in a spreadsheet. Greg
                    Trent


                    Good Bad & The Monkey

                      If you know perl, I have a script that will convert for you. The timeline for the GPX export is still unknown. But it will be great!
                      gmaclin


                        If you know perl, I have a script that will convert for you. The timeline for the GPX export is still unknown. But it will be great!
                        I haven't used perl in a long time, but if you don't mind sharing I would like to take a look at what you did. Thanks! Greg
                        Trent


                        Good Bad & The Monkey

                          Script for converting RA page source to gmap polyline - ----------------------------------------------------- $var = ""; while (<>) { my $line; $line=$_; $var = $var . $line; } $var=~ s/%3c/\t\\n/og; $var=~ s/%2f/\//og; $var=~ s/%20/ /og; $var=~ s/%3d/\=/og; $var=~ s/%22/\"/og; $var=~ s/index\=\"\d*\"\s//og; $var=~ s/x/lng/og; $var=~ s/y/lat/og; $var=~ s/Point/point/og; print $var; ----------------------------------------------------- Script for converting GPX to gmap polyline - ----------------------------------------------------- $var = ""; while (<>) { my $line; $line=$_; $var = $var . $line; } $var=~ s/\< *trkpt="" lat="\"(\-*\d*\.\d*)\"" lon="\"(\-*\d*\.\d*)\"\" />.*?\/trkpt\>/\t\< *point="" lng="\"$2\"" lat="\"$1\"" \/\="" />\n/og; print $var; ----------------------------------------------------- (Basically, you need to reverse the second script's expression in the $var =~ line) MTA : Greg, in the second script, second to last line, I had to add some " *" to make the code read correctly in RA, you will need to remove them.
                          gmaclin


                            Script for converting RA page source to gmap polyline...
                            Thanks Trent! I'll take a look at the scripts and see if I can get them to work. It's too bad my job interferes so much with my fun! Greg
                            Trent


                            Good Bad & The Monkey

                              The scripts are very blunt and lazy, but the get the job done and should be pretty easy to understand as a result. See my note after MTA, above.
                              gmaclin


                                Trent: Using the info from your script above, I was able to get elevation data from RunningAHEAD. (By the way, using the above technique, the elevation data from RunningAHEAD is sampled every 200 meters or 0.124 miles.) I have now been able to use my spreadsheet to analyze and graph Flying Monkey elevation data from maps drawn at 3 different sites: MapMyRun.com: ============= Map: http://www.mapmyrun.com/run/united-states/tn/nashville/429992295 Altitude data points: Every 0.05 miles Altitude gain/loss: Calculated/averaged every 0.1 miles Total Altitude gain: 1762 Total Altitude loss: -1764 Net Altitude Gain/Loss: -2 Difficulty factor: 1.02985117 Comparison to 3:30:00 flat marathon: +0:06:16 RunningAHEAD: ============= Map: http://runningahead.com/maps/fa0bb31f546d4bd280de2b483a2f89a7 Altitude data points: Every 0.124 miles Altitude gain/loss: Calculated/averaged every 0.1 miles Total Altitude gain: 2042 Total Altitude loss: -2020 Net Altitude Gain/Loss: 23 Difficulty factor: 1.03356248 Comparison to 3:30:00 flat marathon: +0:07:03 Motion Based: ============= Map: http://trail.motionbased.com/trail/activity/4490407 Altitude data points: Depends on pace of runner w/GPS unit, but averages once per 0.008 miles Altitude gain/loss: Calculated/averaged every 0.1 miles Total Altitude gain: 2496 Total Altitude loss: -2486 Net Altitude Gain/Loss: 9 Difficulty factor: 1.03972663 Comparison to 3:30:00 flat marathon: +0:08:21 Here are the graphs from these generated by my spreadsheet, drawn side-by-side: http://www.pbase.com/gmaclin/image/97522108/original I drew the map at MapMyRun.com myself, carefully following the roads on the satellite images (fixed from the last time you saw it). I think you drew the one at RunningAHEAD, and the one from MotionBased was generated by a GPS unit worn by someone running the race at last year's event. Comsumer quality GPS systems have a tendency to cause your current position to "waver" back and forth horizontally across the ground and even worse with altitude. If you are on a road/trail that is traversing a slope (i.e. not going directly up/down the slope), the "wavering" effect of the GPS can cause the graph of the altitude values to get a series of "bumps", as shown in the graph from MotionBased. I thought you would be intested in seeing this. Greg
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