Experienced runners naturally optimize stride rate in a manner that
minimizes oxygen uptake at given running speeds. However, as runners become
fatigued, preferred stride rate often decreases. Whether such changes with fatigue
occur in parallel with changes in optimal stride rate is unknown. This study's focus
was on determining whether experienced runners self-optimize stride rate
throughout a near-maximal one-hour run. A secondary focus was to determine if
vertical stiffness is associated with decreases in stride rate.
Seventeen subjects completed a one-hour near-maximal effort run on a
treadmill. After the first five minutes, preferred and optimal stride rates were
measured. Ground reaction force data were used to determine preferred stride rate
averaged over ten strides. Runners completed five two-minute segments of
running at preferred stride rate, 4% and 8% above and below their preferred rate.
Oxygen uptake was measured during the second minute of each two-minute
segment. Fitting a second-degree polynomial through oxygen uptake versus stride
rate data provided a minimum value for oxygen uptake from which optimal stride
rate was determined. Fifty minutes into the run, optimal stride rate was measured
again.
Repeated measures ANOVA showed no difference between preferred and
optimal stride rates at the beginning or at the end of the run, but a decrease in
optimal stride rate was observed from beginning to end. About half of the subjects
decreased preferred and optimal stride rate over the course of the hour run while
the other half showed little or no change.
Vertical stiffness was measured based upon center of mass vertical
displacement and active peak force. Decreases in preferred stride rate over the
course of the hour run were expected to be associated with decreases of vertical
stiffness. However, the changes in stride rate and vertical stiffness were small; no
strong relationship was observed (R²=0.12).
Experienced runners have demonstrated the capability to self-optimize
stride rate at the beginning and near the end of a one hour run. This ability was
observed for runners with substantial shifts of stride rate with fatigue as well as for
runners with no change of stride rate with fatigue. / Graduation date: 2002
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/29717 |
| Date | 12 July 2001 |
| Creators | Hunter, Iain |
| Contributors | Smith, Gerald |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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