Crew Rowing Analysis beyond individual crew members The full video and audio presentation are on www.rowing.chat podcast network. Harjo de Poel did his PhD research at Human Movement Sciences at the Vrije Universiteit Amsterdam (VU). He is now an assistant professor at Department of Human Movement Sciences, at UMCG Groningen. His research is about movement interaction, both within and between persons, in particular in the context of cyclical movements such as rowing. In recent years he has published several papers on this topic.

1. © Harjo de Poel |Pop up symposium “Power in rowing”, VU University 17.12.2019
Crew rowing: analysis beyond the individual crew members
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Harjo J. de Poel, PhD
Department of Human Movement Sciences, University Medical Center Groningen (UMCG)
University of Groningen, The Netherlands
http://www.rug.nl/staff/h.j.de.poel/research
Crew rowing:
analysis beyond the individual crew members

2. © Harjo de Poel |Pop up symposium “Power in rowing”, VU University 17.12.2019
Crew rowing: analysis beyond the individual crew members
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Crew rowing
› an archetype of
synchronization
› … group dynamics
› … interpersonal synergy

3. © Harjo de Poel |Pop up symposium “Power in rowing”, VU University 17.12.2019
Crew rowing: analysis beyond the individual crew members
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Individual vs. crew
› > 95 % of scientific rowing
literature
› Mechanics, physiology, etc.
› 1 discipline
› Very limited literature
› Mainly soc-psych focus
› All disciplines, but 1
› Examination of ‘crew technique’ needed

4. © Harjo de Poel |Pop up symposium “Power in rowing”, VU University 17.12.2019
Crew rowing: analysis beyond the individual crew members
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Crew rowing
e.g., De Poel, De Brouwer, & Cuijpers (2016)
› an archetype of
synchronization, group
dynamics, interpersonal
synergy, …
› deliberate sync
› experts sync better
› crew sync does not
come naturally!
‘Spoiler’ alert!

5. © Harjo de Poel |Pop up symposium “Power in rowing”, VU University 17.12.2019
Crew rowing: analysis beyond the individual crew members
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6. © Harjo de Poel |Pop up symposium “Power in rowing”, VU University 17.12.2019
Crew rowing: analysis beyond the individual crew members
Why crews sync?
 What is the link with
Propulsive Power?
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7. © Harjo de Poel |Pop up symposium “Power in rowing”, VU University 17.12.2019
Crew rowing: analysis beyond the individual crew members
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Power balance on the water
Slippage of blades
in water
± 20%
Boat speed
fluctuations
± 5%
Mechanical power output
Power losses
± 25%
‘Effective’ power
(average speed)
± 75%
e.g., Hofmijster et al., (2007)

8. © Harjo de Poel |Pop up symposium “Power in rowing”, VU University 17.12.2019
Crew rowing: analysis beyond the individual crew members
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Shell speed fluctuations (within cycle)

9. © Harjo de Poel |Pop up symposium “Power in rowing”, VU University 17.12.2019
Crew rowing: analysis beyond the individual crew members
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Figure from Lotte Lintmeijer’s thesis
acceleration
deceleration
deceleration
1) Shell decelerates most around the catch
(rather than during recover)
2) After finish there is still some acceleration

10. © Harjo de Poel |Pop up symposium “Power in rowing”, VU University 17.12.2019
Crew rowing: analysis beyond the individual crew members
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Figure adopted from Hill & Fahrig (2009)
› Crew sync in ms  in ‘%cycle’
› Crew sync consistency
poor crew sync  enhanced boat rocking

11. © Harjo de Poel |Pop up symposium “Power in rowing”, VU University 17.12.2019
Crew rowing: analysis beyond the individual crew members
On-water 2x rowing
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Cuijpers, et al. (2017)
Crew sync
based on
oar angles

12. © Harjo de Poel |Pop up symposium “Power in rowing”, VU University 17.12.2019
Crew rowing: analysis beyond the individual crew members
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Poorer sync is more efficient
r = -0.53* r = -0.51 r = -0.68*
r = -0.56*
r = -0.41
Cuijpers, et al. (2017)

13. © Harjo de Poel |Pop up symposium “Power in rowing”, VU University 17.12.2019
Crew rowing: analysis beyond the individual crew members
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Shell velocity fluctuations
› Due to propulsion – recovery & sliding seats
› Pdrag = k·v3
 if constant boat speed : less power needed
Figure adopted from Hill & Fahrig (2009)

14. © Harjo de Poel |Pop up symposium “Power in rowing”, VU University 17.12.2019
Crew rowing: analysis beyond the individual crew members
Crew sync of forces
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Between rower timing
Force profiles of all oars
- Drawback: only during drive

15. © Harjo de Poel |Pop up symposium “Power in rowing”, VU University 17.12.2019
Crew rowing: analysis beyond the individual crew members
What about crews >2?
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= average force profile
of all oars
Wing & Woodburn (1995)

16. © Harjo de Poel |Pop up symposium “Power in rowing”, VU University 17.12.2019
Crew rowing: analysis beyond the individual crew members
What about crews >2?
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= average force profile
of all oars
Principal Component Analysis:
R2 of 1st PC = 99,6%
Eigenvector_coeff =
[ 0.5063 0.5190 0.5250 0.4458]

17. © Harjo de Poel |Pop up symposium “Power in rowing”, VU University 17.12.2019
Crew rowing: analysis beyond the individual crew members
And now for some fun,
controversial stuff
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18. © Harjo de Poel |Pop up symposium “Power in rowing”, VU University 17.12.2019
Crew rowing: analysis beyond the individual crew members
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Shell velocity fluctuations
› Due to propulsion – recovery & sliding seats
› Pdrag = k·v3
 if constant boat speed : less power needed
› Minimizing velocity fluctuations
› … by ‘out-of-phase’ crew rowing
Figure adopted from Hill & Fahrig (2009)

19. © Harjo de Poel |Pop up symposium “Power in rowing”, VU University 17.12.2019
Crew rowing: analysis beyond the individual crew members
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The ‘myth’ of syncopated rowing

20. © Harjo de Poel |Pop up symposium “Power in rowing”, VU University 17.12.2019
Crew rowing: analysis beyond the individual crew members
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21. © Harjo de Poel |Pop up symposium “Power in rowing”, VU University 17.12.2019
Crew rowing: analysis beyond the individual crew members
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Germany 1955
USSR women 4, 1980

22. © Harjo de Poel |Pop up symposium “Power in rowing”, VU University 17.12.2019
Crew rowing: analysis beyond the individual crew members
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Synchronous (in-phase) Quarter cycle pattern
› Such a pattern is intrinsically unstable in general,
De Brouwer, De Poel, & Hofmijster (2013)
De Poel, De Brouwer, & Cuijpers (2016)
Cuijpers, Zaal, & De Poel (2015)

23. © Harjo de Poel |Pop up symposium “Power in rowing”, VU University 17.12.2019
Crew rowing: analysis beyond the individual crew members
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Can rowers maintain out-of-phase rowing
on ergometers?
› ‘Quarter’ pattern on ergometers side by side
› Coordination breakdown already at
24 strokes/min
› Antiphase rowing (divide crew ‘in two’)
› No breakdowns for antiphase!
De Poel, De Brouwer, & Cuijpers (2016)

24. © Harjo de Poel |Pop up symposium “Power in rowing”, VU University 17.12.2019
Crew rowing: analysis beyond the individual crew members
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AntiphaseIn-phase
De Brouwer, De Poel, & Hofmijster (2013)

25. © Harjo de Poel |Pop up symposium “Power in rowing”, VU University 17.12.2019
Crew rowing: analysis beyond the individual crew members
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AntiphaseIn-phase
Predictions : reduction of shell velocity fluctuations
results in 3 to 10s (!?) gain on 2000 m race
De Brouwer, De Poel, & Hofmijster (2013)

26. © Harjo de Poel |Pop up symposium “Power in rowing”, VU University 17.12.2019
Crew rowing: analysis beyond the individual crew members
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Cuijpers, Zaal, Lemmink, & De Poel (2020)

27. © Harjo de Poel |Pop up symposium “Power in rowing”, VU University 17.12.2019
Crew rowing: analysis beyond the individual crew members
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Crew rowing in sum…
› Importance of analysis at level of crew
coordination
› ‘Superorganism’ (De Poel et al., 2020)
› Relation sync  propulsion
› Power production-efficiency tradeoff

28. © Harjo de Poel |Pop up symposium “Power in rowing”, VU University 17.12.2019
Crew rowing: analysis beyond the individual crew members
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Harjo J. de Poel, PhD
Center for Human Movement Sciences, University Medical Center Groningen (UMCG)
University of Groningen, The Netherlands
http://www.rug.nl/staff/h.j.de.poel/research
Crew rowing:
analysis beyond the individual crew members