PMID- 26957939
OWN - NLM
STAT- PubMed-not-MEDLINE
DCOM- 20160309
LR  - 20240324
IS  - 1303-2968 (Print)
IS  - 1303-2968 (Electronic)
IS  - 1303-2968 (Linking)
VI  - 15
IP  - 1
DP  - 2016 Mar
TI  - Reliability of Three-Dimensional Angular Kinematics and Kinetics of Swimming 
      Derived from Digitized Video.
PG  - 158-66
AB  - The purpose of this study was to explore the reliability of estimating 
      three-dimensional (3D) angular kinematics and kinetics of a swimmer derived from 
      digitized video. Two high-level front crawl swimmers and one high level 
      backstroke swimmer were recorded by four underwater and two above water video 
      cameras. One of the front crawl swimmers was digitized at 50 fields per second 
      with a window for smoothing by a 4(th) order Butterworth digital filter extending 
      10 fields beyond the start and finish of the stroke cycle (FC1), while the other 
      front crawl (FC2) and backstroke (BS) swimmer were digitized at 25 frames per 
      second with the window extending five frames beyond the start and finish of the 
      stroke cycle. Each camera view of one stroke cycle was digitized five times 
      yielding five independent 3D data sets from which whole body centre of mass (CM) 
      yaw, pitch, roll, and torques were derived together with wrist and ankle moment 
      arms with respect to an inertial reference system with origin at the CM. 
      Coefficients of repeatability ranging from r = 0.93 to r = 0.99 indicated that 
      both digitising sampling rates and extrapolation methods are sufficiently 
      reliable to identify real differences in net torque production. This will enable 
      the sources of rotations about the three axes to be explained in future research. 
      Errors in angular kinematics and displacements of the wrist and ankles relative 
      to range of motion were small for all but the ankles in the X (swimming) 
      direction for FC2 who had a very vigorous kick. To avoid large errors when 
      digitising the ankles of swimmers with vigorous kicks it is recommended that a 
      marker on the shank could be used to calculate the ankle position based on the 
      known displacements between knee, shank, and ankle markers. Key pointsUsing the 
      methods described, an inverse dynamics approach based on 3D position data 
      digitized manually from multiple camera views above and below the water surface 
      is sufficiently reliable to yield insights regarding torque production in 
      swimming additional to those of other approaches.The ability to link the torque 
      profiles to swimming actions and technique is enhanced by having additional data 
      such as wrist and ankle displacements that can be obtained readily from the 
      digitized data.An additional marker on the shank should be used to improve 
      accuracy and reliability of calculating the ankle motion for swimmers with a 
      vigorous kick.
FAU - Sanders, Ross H
AU  - Sanders RH
AD  - Faculty of Health Sciences, The University of Sydney , Sydney, Australia.
FAU - Gonjo, Tomohiro
AU  - Gonjo T
AD  - Institute of Sport Physical Education and Health Sciences, The University of 
      Edinburgh.
FAU - McCabe, Carla B
AU  - McCabe CB
AD  - School of Sport, Ulster University , Jordanstown, UK.
LA  - eng
PT  - Journal Article
DEP - 20160223
PL  - Turkey
TA  - J Sports Sci Med
JT  - Journal of sports science & medicine
JID - 101174629
PMC - PMC4763835
OTO - NOTNLM
OT  - Inverse dynamics
OT  - angular kinetics
OT  - asymmetry
OT  - reliability
OT  - swimming
EDAT- 2016/03/10 06:00
MHDA- 2016/03/10 06:01
PMCR- 2016/02/23
CRDT- 2016/03/10 06:00
PHST- 2015/06/19 00:00 [received]
PHST- 2016/01/21 00:00 [accepted]
PHST- 2016/03/10 06:00 [entrez]
PHST- 2016/03/10 06:00 [pubmed]
PHST- 2016/03/10 06:01 [medline]
PHST- 2016/02/23 00:00 [pmc-release]
AID - jssm-15-158 [pii]
PST - epublish
SO  - J Sports Sci Med. 2016 Feb 23;15(1):158-66. eCollection 2016 Mar.