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# Mechanisms of submaximal (quasi-)isometric knee extension exercise related to dinghy sailing performance

(2014)
Author
Promoter
(UGent) and (UGent)
Organization
Project
Olympic Dinghy Sailing 2009-2012 (financial support from the Flemish Government, Department of Culture, Youth, Sports & Media)
Abstract
Dinghy sailing performance is related to hiking endurance (Blackburn & Hubinger, 1995; Tan et al., 2006; Vangelakoudi et al., 2007). However, there is no clear understanding of the underlying physiological mechanisms of hiking. Previous studies established during upwind sailing a significant disproportionate increase in heart rate (up to 75 % HRpeak) and oxygen uptake (up to 40 % VO2peak), reflecting the isometric tension on the anterior body muscles (Vogiatzis et al., 1995). Furthermore, significant increases in both systolic and diastolic blood pressure indicate the isometric nature of this exercise (Blackburn, 1994). However, lactate concentration ([La]) during upwind sailing does not exceed 4 mmol·l-1 which suggests only a small oxygen and energy deficit during upwind sailing (Vogiatzis et al., 2008). Consensus was reached to use the term quasi-isometric to categorise the hiking exercise (Spurway, 2007). In the mean time, the cardiorespiratory, -vascular and metabolic demands during upwind sailing have been thoroughly investigated whereas the muscular mechanisms have only been superficially studied. This research enhances our understanding of dinghy sailing performance by pursuing 3 research aims, that is: (1) investigating the determinants of dinghy sailing performance, (2) developing a sailing ergometer which accurately represents the physiological responses during on-water upwind sailing, and (3) exploring the physiological mechanisms during submaximal (quasi-)isometric knee extension exercise (as a part of upwind sailing exercise) with a distinct focus on the muscle level. To achieve these goals, five studies with each their own purpose and design have been conducted. The illustration (A) above demonstrates the different study populations, designs, methods and aims. Results and conclusions: The determinants of dinghy sailing performance include motor coordination skills and incremental knee extension strength. Motor coordination skills for Optimist sailors (i.e. ≤ 15 years) were highly related to sailing level, whereas incremental knee extension strength endurance (i.e. measured by bucket test) for dynamic hikers (i.e. > 15 years) was related to sailing level. The contribution of incremental knee extension strength endurance to performance for Optimist and Laser sailors was related to a delay in muscle fatigue. The muscle fatigue for Laser sailors was clearly related to maximal quadriceps strength. This result emphasizes the importance of implementing dry-land motor coordination skill training for Optimist sailors and dry-land maximal strength training for Laser sailors. In addition, an innovative biologically validated upwind sailing emulation ergometer was developed by applying a biofeedback system to measure the hiking moment. As such, the researcher can impose a certain quasi-isometric upwind sailing protocol to several subjects or to one subject on different occasions. The emulation ergometer can be implemented as tool for sailing performance diagnostics and training follow-up. Optimist and Laser sailors’ quadriceps muscle fatigue (as indicated by a decrease in mean power frequency an increase in root mean square) increased throughout submaximal (quasi-)isometric knee extension exercise (as a part of upwind sailing exercise). However, after an initial increase, a steady state phase was observed, presumably due to compensation strategies (e.g. tacking, fore and aft movements, and alternate-legs-strategy) conducted by the sailors to delay exhaustion. This results in a momentary relaxation of the quadriceps muscle causing a rapid outflow of deoxygenated blood and inflow of fresh oxygenated blood. Optimist sailors possess other fiber recruitment or O2 extraction patterns, probably to postpone exhaustion and increase knee extension strength endurance, than untrained controls.

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## Citation

Please use this url to cite or link to this publication:

Chicago
Callewaert, Margot. 2014. “Mechanisms of Submaximal (quasi-)isometric Knee Extension Exercise Related to Dinghy Sailing Performance”. Ghent, Belgium: Ghent University. Faculty of Medicine and Health Sciences.
APA
Callewaert, M. (2014). Mechanisms of submaximal (quasi-)isometric knee extension exercise related to dinghy sailing performance. Ghent University. Faculty of Medicine and Health Sciences, Ghent, Belgium.
Vancouver
1.
Callewaert M. Mechanisms of submaximal (quasi-)isometric knee extension exercise related to dinghy sailing performance. [Ghent, Belgium]: Ghent University. Faculty of Medicine and Health Sciences; 2014.
MLA
Callewaert, Margot. “Mechanisms of Submaximal (quasi-)isometric Knee Extension Exercise Related to Dinghy Sailing Performance.” 2014 : n. pag. Print.
@phdthesis{5723071,
abstract     = {Dinghy sailing performance is related to hiking endurance (Blackburn \& Hubinger, 1995; Tan et al., 2006; Vangelakoudi et al., 2007). However, there is no clear understanding of the underlying physiological mechanisms of hiking. Previous studies established during upwind sailing a significant disproportionate increase in heart rate (up to 75 \% HRpeak) and oxygen uptake (up to 40 \% VO2peak), reflecting the isometric tension on the anterior body muscles (Vogiatzis et al., 1995). Furthermore, significant increases in both systolic and diastolic blood pressure indicate the isometric nature of this exercise (Blackburn, 1994). However, lactate concentration ([La]) during upwind sailing does not exceed 4 mmol{\textperiodcentered}l-1 which suggests only a small oxygen and energy deficit during upwind sailing (Vogiatzis et al., 2008). Consensus was reached to use the term quasi-isometric to categorise the hiking exercise (Spurway, 2007). In the mean time, the cardiorespiratory, -vascular and metabolic demands during upwind sailing have been thoroughly investigated whereas the muscular mechanisms have only been superficially studied. This research enhances our understanding of dinghy sailing performance by pursuing 3 research aims, that is: (1) investigating the determinants of dinghy sailing performance, (2) developing a sailing ergometer which accurately represents the physiological responses during on-water upwind sailing, and (3) exploring the physiological mechanisms during submaximal (quasi-)isometric knee extension exercise (as a part of upwind sailing exercise) with a distinct focus on the muscle level. To achieve these goals, five studies with each their own purpose and design have been conducted. The illustration (A) above demonstrates the different study populations, designs, methods and aims.
Results and conclusions: The determinants of dinghy sailing performance include motor coordination skills and incremental knee extension strength. Motor coordination skills for Optimist sailors (i.e. \ensuremath{\leq} 15 years) were highly related to sailing level, whereas incremental knee extension strength endurance (i.e. measured by bucket test) for dynamic hikers (i.e. {\textrangle} 15 years) was related to sailing level. The contribution of incremental knee extension strength endurance to performance for Optimist and Laser sailors was related to a delay in muscle fatigue. The muscle fatigue for Laser sailors was clearly related to maximal quadriceps strength. This result emphasizes the importance of implementing dry-land motor coordination skill training for Optimist sailors and dry-land maximal strength training for Laser sailors. In addition, an innovative biologically validated upwind sailing emulation ergometer was developed by applying a biofeedback system to measure the hiking moment. As such, the researcher can impose a certain quasi-isometric upwind sailing protocol to several subjects or to one subject on different occasions. The emulation ergometer can be implemented as tool for sailing performance diagnostics and training follow-up. Optimist and Laser sailors{\textquoteright} quadriceps muscle fatigue (as indicated by a decrease in mean power frequency an increase in root mean square) increased throughout submaximal (quasi-)isometric knee extension exercise (as a part of upwind sailing exercise). However, after an initial increase, a steady state phase was observed, presumably due to compensation strategies (e.g. tacking, fore and aft movements, and alternate-legs-strategy) conducted by the sailors to delay exhaustion. This results in a momentary relaxation of the quadriceps muscle causing a rapid outflow of deoxygenated blood and inflow of fresh oxygenated blood. Optimist sailors possess other fiber recruitment or O2 extraction patterns, probably to postpone exhaustion and increase knee extension strength endurance, than untrained controls.},
author       = {Callewaert, Margot},
isbn         = {9789078836087},
language     = {eng},
pages        = {220},
publisher    = {Ghent University. Faculty of Medicine and Health Sciences},
school       = {Ghent University},
title        = {Mechanisms of submaximal (quasi-)isometric knee extension exercise related to dinghy sailing performance},
year         = {2014},
}