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Quick Running Dynamics Question (Read 204 times)

mab411


Proboscis Colossus

    So, a couple weeks back, I got my Garmin FR620 with the HRM and as predicted, I'm obsessing over the "running dynamics."  Don't worry, it'll pass.  Same thing happened over heart rate when I got my first HRM a couple years ago.

     

    But I'm having fun for now, seeing what my vertical oscillation and ground contact time and such is, and yeah, seeing if there are any clues there about whether my form could use improvement.

     

    My "quick question" is, when I back off the pace for a recovery run, should any of the running dynamics stay the same?  Or would they adjust up or down accordingly, as I suspect?  The slower my pace, the more my vertical oscillation and ground contact time go up and my cadence goes down.  Seems pretty obvious, just want to make sure I'm not seeing something that I need to tweak.

     

    ...and yes, I know the danger of making big alterations to my form in the middle of a training cycle, and don't plan on doing so.  Just wondering how what I'm seeing stacks up.

    "God guides us on our journey, but careful with those feet." - David Lee Roth, of all people

    Joann Y


      I honestly don't see how data from the Garmin is going to tell you anything meaningful about running form. I'd be curious as to what others say.

      joescott


        Mr. Mab, it is probably more typical that your cadence would remain roughly constant and rather your VO would decrease as you run at slower paces.  I say this because for many runners the main variable we unconsciously change to modify speed is stride length, not cadence.  Cadence usually stays remarkably constant over a fairly wide range of paces until one gets up toward probably mile pace or faster.  BUT "typical" absolutely does not mean "universal."  One thing the watch may be telling you is that you could be working on running a quicker cadence at slower paces, lowering VO thereby, and thus also lowering injury risk (lower landing forces) and possibly improving running economy while you are at it.  But that's just a theory.  

        - Joe

        We are fragile creatures on collision with our judgment day.

        mab411


        Proboscis Colossus

          Mr. Mab, it is probably more typical that your cadence would remain roughly constant and rather your VO would decrease as you run at slower paces.  I say this because for many runners the main variable we unconsciously change to modify speed is stride length, not cadence.  Cadence usually stays remarkably constant over a fairly wide range of paces until one gets up toward probably mile pace or faster.  BUT "typical" absolutely does not mean "universal."  One thing the watch may be telling you is that you could be working on running a quicker cadence at slower paces, lowering VO thereby, and thus also lowering injury risk (lower landing forces) and possibly improving running economy while you are at it.  But that's just a theory.  

           

          Hmm, interesting, thanks.

           

          I can tell you, my cadence varies pretty dramatically, from around 170 at recovery pace to 205 for speedwork.  Tempo runs are at around 185.

          "God guides us on our journey, but careful with those feet." - David Lee Roth, of all people

          TJoseph


            I don't have a 620, but I just bought another footpod (I lost my last one) to play with a program called Virtual Runner on the treadmill.  My cadence is much lower than the recommended 180 for my easy runs.  It has been steady at about 166.  I have never been a big fan of consciously changing form, but I wonder if there would be a benefit to trying to increase my cadence.  It doesn't really feel comfortable to do so.

            joescott


              mab, I see your skeptically raised eyebrow.... 

               

              Here’s some real data for food for thought. This is from a run I did on May 9, 2012 (was just easy to grab from a sort on my Garmin Connect account). First 3 miles easy. Next 3 miles tempo.

              Easy miles: avg pace = 7:35, avg_speed = 3.54 m/s, avg_cadence = 182, avg stride length = 1.17 meters.

              Tempo miles: avg pace = 6:03, avg speed = 4.45 m/s, avg cadence = 187, avg stride length = 1.42 meters.

               

              Running speed = cadence * stride_length, so you can obviously modulate either to increase speed. In this case, speed increased by 26%. Stride lengthened by 21%. But cadence only increased by a paltry 3%. As I said, this is not a universal truth, but it applies to a lot of runners. For me to see my cadence really increase meaningfully I’ve typically got to be running at least sub 5k pace.

              - Joe

              We are fragile creatures on collision with our judgment day.

              mab411


              Proboscis Colossus

                mab, I see your skeptically raised eyebrow.... 

                 

                Here’s some real data for food for thought. This is from a run I did on May 9, 2012 (was just easy to grab from a sort on my Garmin Connect account). First 3 miles easy. Next 3 miles tempo.

                Easy miles: avg pace = 7:35, avg_speed = 3.54 m/s, avg_cadence = 182, avg stride length = 1.17 meters.

                Tempo miles: avg pace = 6:03, avg speed = 4.45 m/s, avg cadence = 187, avg stride length = 1.42 meters.

                 

                Running speed = cadence * stride_length, so you can obviously modulate either to increase speed. In this case, speed increased by 26%. Stride lengthened by 21%. But cadence only increased by a paltry 3%. As I said, this is not a universal truth, but it applies to a lot of runners. For me to see my cadence really increase meaningfully I’ve typically got to be running at least sub 5k pace.

                 

                Lol, I wouldn't say I'm skeptical, at least not in terms of other peoples' experience!  But I'm kind of with TJoseph, a faster cadence (i.e. as fast as tempo pace) for my easy runs just doesn't "feel" right.  This morning, after checking this thread, I did experiment a bit on my easy run with upping my cadence to about 180 (didn't have the HRM on, but I'm confident that's about right).  I noticed two things: one, I felt funny - like "ha-ha" funny.  Like I was in kind of a cartoonish fast shuffle (NOT saying you or anyone else looks like this on easy runs, it's just how I felt).  Lord knows, I'm not too afraid of looking goofy (I mean, just look at my avatar pic.  That's the face I wear ALL THE TIME), but more significant is the second thing I noticed, that I seemed to be working harder.  That got me curious enough that I'm going to try this again with the HRM on, to get my heart's thoughts on the matter.  Because if increasing my easy cadence will reduce the chance of injury significantly, I'll do it, but if it's going to make my recovery runs less recovery-ey, I'm not so sure.

                 

                So, since I certainly agree with your running speed equation, now I wonder if I'm keeping my stride length the same on my easy runs?  Not sure if the 620 can measure that dynamic (seems like it should, but I don't recall seeing that feature), but if it's important, I guess I can figure it out.

                 

                Modified to remove boneheaded statement about VO.

                "God guides us on our journey, but careful with those feet." - David Lee Roth, of all people

                TJoseph


                  I experimented with increasing my cadence yesterday also.  I only got it up to 172 for a few miles.  I felt like I was working a lot harder and I really had to focus to keep it there.

                  Tim_Easterday


                     

                    Hmm, interesting, thanks.

                     

                    I can tell you, my cadence varies pretty dramatically, from around 170 at recovery pace to 205 for speedwork.  Tempo runs are at around 185.

                     

                    Same here. Doing track intervals my cadence was around 217 while on a long run it was around 182. And my vertical oscillation drops as I run faster.


                    #artbydmcbride

                      I've read (here) you should swing your arms less.  You're welcome. 

                       

                      Runners run

                        and, unless you can win the Boston Marathon, you're a POS.  Records be damned.

                        I've read (here) you should swing your arms less.  You're welcome. 

                        NHLA


                          mab, I see your skeptically raised eyebrow.... 

                           

                          Here’s some real data for food for thought. This is from a run I did on May 9, 2012 (was just easy to grab from a sort on my Garmin Connect account). First 3 miles easy. Next 3 miles tempo.

                          Easy miles: avg pace = 7:35, avg_speed = 3.54 m/s, avg_cadence = 182, avg stride length = 1.17 meters.

                          Tempo miles: avg pace = 6:03, avg speed = 4.45 m/s, avg cadence = 187, avg stride length = 1.42 meters.

                           

                          Running speed = cadence * stride_length, so you can obviously modulate either to increase speed. In this case, speed increased by 26%. Stride lengthened by 21%. But cadence only increased by a paltry 3%. As I said, this is not a universal truth, but it applies to a lot of runners. For me to see my cadence really increase meaningfully I’ve typically got to be running at least sub 5k pace.

                          Interesting. When Jack Daniels came up with the 180 he simply counted the footfalls of elite runners. It always bothered me that it is the same for one mile or 26. It does not make common sense but it must be true. At least for elite runners,

                          It does feel odd running 180 at a slow pace but you get used to it.

                          sport jester


                          Biomimeticist

                            I've read (here) you should swing your arms less.  You're welcome. 

                            Well at least one person here has been paying attention....

                             

                            Running doesn't equal cadence*stride length.

                             

                            A more accurate description would be running speed =cadence* (stride length / running guage) (drift rate ratio).

                             

                            Because the missing variable of step width reduces forward momentum and increases energy expenditure wasted in arm swing.

                             

                            If I could send you to Bora Bora I would

                            Experts said the world is flat

                            Experts said that man would never fly

                            Experts said we'd never go to the moon

                             

                            Name me one of those "experts"...

                             

                            History never remembers the name of experts; just the innovators who had the guts to challenge and prove the "experts" wrong

                            joescott


                              Awesome!  Directly overturned by sport jester!  I could hardly hope for a better validation.

                               

                              'Experts said the world is flat

                              Experts said that man would never fly

                              Experts said we'd never go to the moon

                               

                              Name me one of those "experts"...'

                               

                              By the way, per your request, I name you one of those "experts."

                              - Joe

                              We are fragile creatures on collision with our judgment day.