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TRAINING IMPLICATIONS OF STRIDE LENGTH ANALYSIS

 

By Jack Farrell, XC/Track Coach, Thousand Oaks High School, CA

 

 

Farrell shows why he is one of the best. ..he does his homework. Have any readers done similar studies on their athletes ? From what I read, Farrell just used a video camera and shows how a simple analysis can lead to some very helpful conclusions about running. If you weren't sure why Thousand Oaks has one of the top teams in the country, now you know the rest of the story. Thanks to George Payan of California Coaches Alliance for sending this article in.
 

    In 1992 I attended the Junior Elite Distance Camp at Colorado Springs. The featured presenter was Dr. Jack Daniels and one concept he introduced to us I found very intriguing. He said that stride frequency was fairly fixed and idiosyncratic for each runner-that no matter the pace, the frequency was nearly the same, and that, as a runner increased his pace, the variable was stride length. In other words, the runner increased the length of his stride while maintaining the same basic turnover. He claimed that he and his assistants had done exhaustive stride counts at meets to verify this.
    This topic did not generate much discussion but I felt its implications were enormous for training principles. I had already switched from a hard- easy training regimen to a balanced one and had relied during cross country season on what we called pick-up runs, but Daniels' claim formed the theoretical basis for what we were already doing. Our balanced system called for lactate threshold runs, or tempo runs, virtually every day.
    A few principles became clear to me as a result of this theory:

  1. The motion of running, at its most elemental level, is really jumping, or a series of controlled bounces.

  2. Increased oxygen uptake would allow a runner to sustain a longer bounce with each stride.

  3. This is the reason elite runners, for instance 2:10 marathoners traveling at 4:50 mile pace, look like they are running so easily. In point of fact, their turnover is not significantly different from the 2:36 marathoner who is running 6:00 pace. Their superior oxygen uptake systems allow for a correspondingly elongated stride-a bigger bounce, if you will.

  4. Conventional wisdom has always cautioned against working on stride length for fear of over striding. In actuality, few runners can even accomplish that flaw. Most runners naturally foot-plant under their center of gravity. The longer stride is accomplished by jumping farther with each push-off, not by throwing the foot ahead of the center of gravity.

  5. What allows this longer bounce to develop is increased leg strength, increased flexibility and increased oxygen uptake. Of these three factors, the increase in oxygen uptake is the most significant.

    I have been studying running videos for years now in an attempt to verify some of these principles. Most recently, I had occasion to count strides for Kim Mortensen, the athlete I coached at Thousand Oaks H.S., who last year won the Foot Locker National Cross Country title and set a new national interscholastic record for 3200 meters of 9:48.59. I counted her strides during a training run at 6 minutes/mile pace, during several portions of her second run, during a few portions of her race the following week against Julia Stamps at the International Prep Invitational in Elmhurst, Illinois.
    I found that in training Kim took 194 strides per minute at 6 minutes per mile pace. Kim's stride was there- fore 4'71/2" (or 541/2"). In order to drop her pace from 6:00 minutes per mile in training to 4:55 during her record run, Kim only increased her stride turnover by a factor of 3% to 200 strides per minute. That necessitated an increase of 17% in her stride length to 5' 5 1/4" (65 1/4"). In order to drop her last quarter under 70 seconds and her last 200 to .34.3, Kim's stride frequency only increased by a factor of another 2% to 204 strides per minute, but her stride length increased by only 1.1% to 5' 6" (66"). This suggests that, at least for Kim, she was already at near maximum stride length to be sustained with available oxygen reserves and any increase in pace would have to come from stride frequency, again at virtual max.
    I also counted Julia Stamps' strides during the middle of the state meet 3200. She took 10 fewer strides per minute than Kim, 190 versus 200, while maintaining her position just behind Kim. Her stride in competition, therefore, was somewhat longer than Kim's, 5' 8" per stride vs. 5' 5 1/4" per stride, demonstrating the idiosyncratic nature of this information. This would only have significance if we knew Julia's stride frequency and length during normal training runs. Also, Julia slowed down some 25 seconds during the last 1200 meters. It would be interesting to chart the impact this deceleration had on both stride frequency and stride length. However, the camera remained on Kim and thus I could not count Julia's strides.
    One week later, Kim raced the mile at the International Prep Invitational and ran 4 :47.73. Her stride pattern matched her kick of the Masters Meet, or 204 strides per min. However, her stride length dropped to 5' 4 3/4" (64 3/4"). It took an extra 4 strides per minute at nearly the same length to drop her pace from 4:54 to 4:48, approximately. She did increase her tempo slightly, without a concomitant lengthening of her stride. I still feel the 4:48 was submaximal and would posit that a steep drop in time, say to the low 4:40's, would necessitate at least a moderate lengthening of the stride.
    One of the reasons that Kim was so consistent in racing was that her training was extremely consistent. She ran virtually every day at 6:00 pace all spring. When it came time to race, she was physiologically prepared to make the improvements described above. When a training system calls for vast variations in pace, as the hard-easy system does, it may be more difficult to achieve consistency in racing.
    The question comes to mind: what is the best way to prepare for the stride length increases necessitated by racing? Logically, more speed work, form drills, and plyometrics seem to be in order. Ironically, these activities have little to do with increasing oxygen uptake. A steady diet of 85% runs, about 1:00 per mile above 5K race pace, seems to produce the most dramatic results in oxygen uptake efficiency.
    At Thousand Oaks we use long intervals to simulate race pace and avoid virtually all speedwork during cross country. The most common interval is 1320 yards, or one-quarter of the 3-mile racing distance. We try to run these at race pace. For instance, a 16-min. 3-miler would run 4:00 reps. We usually do four repetitions, which is equal to the racing distance. Highly fit runners need a timed rest of from 60-90 seconds to hold to race pace. Otherwise, with full rest (4- 7 minutes) they tend to run considerably under race pace. This training is more race simulation and pace work than anything else.
    We run these intervals every other Wednesday. On the alternate Wednesday we do what we call a pick-up run. This is similar to a surge run, but there is no backing off of the pace. In a typical 6- or 7-mile run, we designate a point 11/2 to 2 miles from the finish as the pick-up point. Athletes are asked to drop the pace incrementally over the remainder of the run. The general directive is to drop the pace until you are uncomfortable and hold it until you are comfortable, and then drop it again. Runners usually drop the pace about 5-10 seconds per mile and then hold the pace for 45 seconds to a minute before they attempt another drop. A given runner might experience a half a dozen drops in pace before the end and may reach race pace with a half-mile or less to go and even exceed race pace for the last few hundred yards. Fit runners find this workout very stimulating. I think I now understand why it works.
    A runner like Kim traveling at 6 min. pace and 83% of her maximum stride length would experience discomfort when dropping the pace and increasing her stride length. But more oxygen capacity is available and so within a brief period of time she is now striding again at her normal turn- over, but with elongated strides and deeper breathing. A state of homeostasis would be regained until the next drop in pace.
    When oxygen capacity is reached and stride length is maximized, only then would the discomfort remain. This usually coincides with the end of the training run or the end of the race. The pick-up run transitions the body thought the lengthening of stride from training pace to race pace. At training pace (6:00 per mile) and race pace (sub-5:00 per mile) the athlete would look about the same: same cadence, same breathing. The difference would be the length of the stride and the depth of the breathing.
    At least for Kim, the number 83 seems significant. She trains at both 83% of her race pace and also 83% of her stride length. Exercise physiologists talk of the percentage of maximal oxygen uptake and the percentage of maximum heart rate in training. As a coach I do very little in trying to determine these values. It would be interesting to see what percentage Kim is training and racing at in these two areas.
    All of these results are tentative and self-correcting as I make more observations. And I do plan to continue examining future runners and the adjustments they make to move from training pace to race pace. It was my main intent to open dialogue on this important training issue.

 

FROM: TRACK COACH 138 (WINTER 1997)

 

 

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