DISCUSSION
The intent of this work was to address the lack of standardized
protocols for the analysis of numeric time and motion data
from field sport athletes. We would have recommended
that velocity ranges and sprint definitions published previously
be adopted as the standard, but no single protocol
appears to have been widely endorsed, and all appear to have
been developed subjectively. Furthermore, the need for
standards is important because we anticipate an increase in
the publication of time-motion data in the future as the
enabling technology (GPS, radiofrequency transponders,
video analysis software, etc.) becomes more widely used.
The method used to identify velocity ranges in the present
workmade the assumption that each type of locomotion (walk,
jog, run, and sprint) has a typical range of velocities that can be
described by a distribution curve. This assumption was based
on the observation that there is
a peak in the velocity distribution
curve of all data sets we
analyzed that coincide with the
typical average walking velocity
(;1.2 ms21 or ;4.3 kmh21).
This velocity peak appears to be
Gaussian in shape and represents
the large amount of time
spent walking during play. This
feature of the data reflects what
early time-motion analysis publications
that used video analysis
revealed—field sport athletes
spend a large proportion of
match play walking (9,15,19).
Based on this finding,
we extended our initial assumption
further to include the
presence of velocity distribution
curves that represent the other locomotor categories. The next
step was to attempt to identify these distribution curves in the
overall distribution curve using a process of optimizedmultiple
curve fitting. The intersection of these component curves was
nominated as the boundary of each velocity range.
There are several limitations of this method including the
likelihood that the component distribution curves are not
normal and are almost certainly skewed. The component
curves do not fit the overall distribution curve well where
they intersect with each other. The locomotor category of
‘‘standing’’ had to be included as a velocity range because it is
a relatively important part of time-motion analysis but
excluded from the curve fitting process because, by
definition, it should not involve any velocity. It was excluded
from the curve fitting process but was arbitrarily defined as
any velocity between 0.0 and 0.1 ms21. The velocity 0.1
ms21 was included in the standing velocity range because
the velocity distribution curves of the data sets used in the
present work include a ‘‘standing’’ peak that includes this
value (Figure 1). The likely cause of this ‘‘standing’’ peak is
the noise inherent in the GPS signal meaning that even
when a GPS receiver is stationary, it reports very small
changes in position and therefore velocity.
Overall, the velocity ranges for the 5 sports we analyzed
were quite similar. The largest difference occurred at the
threshold sprinting velocity between men’s soccer and either
women’s soccer or women’s field hockey. There was also
a 0.7-ms21 difference between the threshold jogging velocity
between AFL and either forms of field hockey. We consider
the differences in velocity ranges between the 5 sports we
analyzed to be relatively small, but the use of an averaged set
of velocity ranges for all sports may cause slight overestimation
or underestimation in the relative amount of
activity in each locomotor category. Although, using sportspecific
velocity ranges removes the opportunity to make
สนทนาจุดประสงค์ของงานนี้คือการไม่มีมาตรฐานโปรโตคอลสำหรับการวิเคราะห์ข้อมูลตัวเลขเวลาและการเคลื่อนไหวจากฟิลด์กีฬานักกีฬา เราจะแนะนำที่ช่วงความเร็วและวิ่งกำหนดเผยแพร่ก่อนหน้านี้สามารถนำมาใช้เป็นมาตรฐาน แต่ไม่มีโพรโทคอลเดียวดูเหมือนจะมีการแพร่หลายรับรอง และทั้งหมดจะมีการพัฒนา subjectively ขึ้น นอกจากนี้ ต้องการมาตรฐานเป็นสิ่งสำคัญเนื่องจากเราคาดว่าจะมีการเพิ่มขึ้นความเคลื่อนไหวเวลาข้อมูลในอนาคตเปิดใช้งานเทคโนโลยี (จีพีเอส ดาวเทียม radiofrequencyซอฟต์แวร์วิเคราะห์วิดีโอ ฯลฯ) กลายเป็นวงกว้างใช้วิธีการที่ใช้เพื่อระบุช่วงความเร็วในปัจจุบันworkmade อัสสัมแต่ละชนิดของ locomotion (เดินวิ่ง วิ่ง และวิ่ง) มีช่วงปกติของตะกอนที่สามารถอธิบาย โดยเส้นโค้งการกระจาย นี้ขึ้นอยู่กับในการเก็บข้อมูลที่มีสูงสุดในการกระจายความเร็วกำหนดเส้นโค้งของข้อมูลทั้งหมดที่เราวิเคราะห์ที่สอดคล้องกับการค่าเฉลี่ยทั่วไปที่เดินเร็ว(; s21 1.2 เมตร หรือ h21 4.3 km)ความเร็วช่วงนี้ดูเหมือนจะ เป็นGaussian ในรูปร่างและแสดงจำนวนมากของเวลาใช้เวลาเดินในระหว่างการเล่น นี้คุณลักษณะของข้อมูลสะท้อนอะไรสิ่งพิมพ์การวิเคราะห์การเคลื่อนไหวครั้งก่อนที่ใช้วิเคราะห์วิดีโอเปิดเผยเช่นฟิลด์นักกีฬากีฬาใช้สัดส่วนใหญ่ของเล่นจับคู่เดิน (9,15,19)ตามนี้ค้นหาเราเพิ่มเติมสมมติฐานเบื้องต้นของเราfurther to include thepresence of velocity distributioncurves that represent the other locomotor categories. The nextstep was to attempt to identify these distribution curves in theoverall distribution curve using a process of optimizedmultiplecurve fitting. The intersection of these component curves wasnominated as the boundary of each velocity range.There are several limitations of this method including thelikelihood that the component distribution curves are notnormal and are almost certainly skewed. The componentcurves do not fit the overall distribution curve well wherethey intersect with each other. The locomotor category of‘‘standing’’ had to be included as a velocity range because it isa relatively important part of time-motion analysis butexcluded from the curve fitting process because, bydefinition, it should not involve any velocity. It was excludedfrom the curve fitting process but was arbitrarily defined asany velocity between 0.0 and 0.1 ms21. The velocity 0.1ms21 was included in the standing velocity range becausethe velocity distribution curves of the data sets used in thepresent work include a ‘‘standing’’ peak that includes thisvalue (Figure 1). The likely cause of this ‘‘standing’’ peak isthe noise inherent in the GPS signal meaning that evenwhen a GPS receiver is stationary, it reports very smallchanges in position and therefore velocity.Overall, the velocity ranges for the 5 sports we analyzedwere quite similar. The largest difference occurred at thethreshold sprinting velocity between men’s soccer and eitherwomen’s soccer or women’s field hockey. There was alsoa 0.7-ms21 difference between the threshold jogging velocitybetween AFL and either forms of field hockey. We considerthe differences in velocity ranges between the 5 sports weanalyzed to be relatively small, but the use of an averaged setof velocity ranges for all sports may cause slight overestimationor underestimation in the relative amount ofactivity in each locomotor category. Although, using sportspecificvelocity ranges removes the opportunity to make
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