Volume 9, Issue 3 (12-2023)
J Sport Biomech 2023, 9(3): 178-191 |
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Qeysari S F, Emamrezaii S, Eslamizad A, Qeysari S K. Comparison of External Focus Instructions Based on Mechanics and Performance in the Vertical jump: Examining the constrained action hypothesis. J Sport Biomech 2023; 9 (3) :178-191
URL: http://biomechanics.iauh.ac.ir/article-1-321-en.html
URL: http://biomechanics.iauh.ac.ir/article-1-321-en.html
1- Department of Motor Behavior, Faculty of Physical Education and Sports Sciences, University of Tehran, Tehran, Iran.
2- Department of Sport Physiology, Faculty of Physical Education and Sport Sciences, University of Lorestan, Lorestan, Iran.
3- Department of Motor behavior, Faculty of Physical Education and Sports Sciences, Central Tehran Branch, Islamic Azad University, Tehran, Iran.
4- Department of Physics, Faculty of Physics, University of Tehran, Tehran, Iran.
2- Department of Sport Physiology, Faculty of Physical Education and Sport Sciences, University of Lorestan, Lorestan, Iran.
3- Department of Motor behavior, Faculty of Physical Education and Sports Sciences, Central Tehran Branch, Islamic Azad University, Tehran, Iran.
4- Department of Physics, Faculty of Physics, University of Tehran, Tehran, Iran.
Keywords: External focus based on performance, External focus based on mechanics, Electromyography, Vertical jump
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Extended Abstract
1. Introduction
For motor skills in which the goal is to correct movement rather than enhance performance, previous research has demonstrated that using externally focused instructions improves safe landing mechanics (21, 23). However, the instructions provided were specific to performance, despite the goal being movement correction. It is possible that the benefits of external focus would be more profound if the instructional cues were specific to mechanics. Therefore, the purpose of this study was to compare externally focused instructions specific to performance with external focus instructions specific to mechanics. We hypothesize that external focus instructions specific to performance (external focus-performance) will be superior to baseline (i.e., "do your best" with no external focus instructions) and external focus instructions specific to mechanics (external focus-mechanics). We also hypothesize that external focus-mechanics will improve mechanics more than external focus-performance and baseline. We chose not to include an internal focus condition based on previous literature showing the superior effects of an external focus of attention in tasks examining jump performance. Several studies have shown the superiority of external focus of attention in vertical jumps. However, research investigating the level of electrical activity of the Rectus abdominis muscle as a trunk stabilizer muscle during vertical jumps has been lacking. Therefore, the aim of this study was to investigate the effect of different instructions of external focus on the electrical activity of the rectus abdominis muscle during vertical jumps.
2. Methods
The present research design was semi-experimental in terms of the method and within-group. The advantage of this design (within-group design) is that problems related to differences between participants (such as height, strength, or skill level) are reduced. For this purpose, 12 male professional volleyball players (average age 24.0±1.92 years; average weight 73.5±8.7 kg) voluntarily participated in this research. At the time of conducting the research, the subjects participated in intra-university volleyball competitions and during the last two years, they were regularly active in volleyball. These criteria greatly reduce the amount of fatigue during the implementation of the research because fatigue can shift the focus of attention towards the body (internal focus). Subjects performed the vertical jump movement with all their strength in two external focus situations (1- performance-based external focus, 2- mechanics-based external focus) on the force plate. During jumping, surface electromyography signals of the right abdominal muscle were recorded using an electromyography device that was simultaneous with a force plate device in terms of time.
3. Results
The results of the paired t-test showed that the jump height in the performance-based external focus condition was significantly higher than in the mechanics-based external focus condition (P<0.001). Additionally, the external attention focused on mechanics compared to performance-based external attention caused a significant increase in the electrical activity of the right abdominal muscle during the concentric phase (P<0.001). However, there was no significant difference in the eccentric phase of the electrical activity of the right abdominal muscle between the two conditions (P=0.233). The results of the correlated t-test comparing the maximum force applied to the force plate before leaving the ground indicate the maximum knee angle in the outward phase of the movement. The results of the paired t-test showed that this force was significantly higher in the mechanics-based external focus condition than in the performance-based external focus condition (P=0.022), indicating that the maximum angle of the knee in the mechanics-based external focus condition exceeded that in the performance-based external focus condition.
4. Conclusion
These results indicate that performance-based external focus instructions lead to greater automaticity of movement and improved performance. However, they are not useful for improving movement mechanics. For this purpose, external focus instructions based on movement mechanics should be used. The decreased electrical activity with more effective results in the performance-based external focus condition is evidence of optimization of intramuscular coordination with the external focus. Therefore, it can be said that the focus of external attention based on mechanics leads to an increase in the electrical activity of the muscles of the lower limbs and is not suitable for skilled individuals in vertical jump movements, although it may be suitable for the initial learning efforts of beginners according to the learning stages.
Ethical Considerations
Compliance with ethical guidelines
There were no ethical considerations to be addressed in this research.
Funding
This research did not receive any grants from funding agencies in the public, commercial, or non-profit sectors.
Authors' contributions
All authors contributed equally to preparing the article.
Conflicts of interest
The authors declared no conflict of interest.
For motor skills in which the goal is to correct movement rather than enhance performance, previous research has demonstrated that using externally focused instructions improves safe landing mechanics (21, 23). However, the instructions provided were specific to performance, despite the goal being movement correction. It is possible that the benefits of external focus would be more profound if the instructional cues were specific to mechanics. Therefore, the purpose of this study was to compare externally focused instructions specific to performance with external focus instructions specific to mechanics. We hypothesize that external focus instructions specific to performance (external focus-performance) will be superior to baseline (i.e., "do your best" with no external focus instructions) and external focus instructions specific to mechanics (external focus-mechanics). We also hypothesize that external focus-mechanics will improve mechanics more than external focus-performance and baseline. We chose not to include an internal focus condition based on previous literature showing the superior effects of an external focus of attention in tasks examining jump performance. Several studies have shown the superiority of external focus of attention in vertical jumps. However, research investigating the level of electrical activity of the Rectus abdominis muscle as a trunk stabilizer muscle during vertical jumps has been lacking. Therefore, the aim of this study was to investigate the effect of different instructions of external focus on the electrical activity of the rectus abdominis muscle during vertical jumps.
2. Methods
The present research design was semi-experimental in terms of the method and within-group. The advantage of this design (within-group design) is that problems related to differences between participants (such as height, strength, or skill level) are reduced. For this purpose, 12 male professional volleyball players (average age 24.0±1.92 years; average weight 73.5±8.7 kg) voluntarily participated in this research. At the time of conducting the research, the subjects participated in intra-university volleyball competitions and during the last two years, they were regularly active in volleyball. These criteria greatly reduce the amount of fatigue during the implementation of the research because fatigue can shift the focus of attention towards the body (internal focus). Subjects performed the vertical jump movement with all their strength in two external focus situations (1- performance-based external focus, 2- mechanics-based external focus) on the force plate. During jumping, surface electromyography signals of the right abdominal muscle were recorded using an electromyography device that was simultaneous with a force plate device in terms of time.
3. Results
The results of the paired t-test showed that the jump height in the performance-based external focus condition was significantly higher than in the mechanics-based external focus condition (P<0.001). Additionally, the external attention focused on mechanics compared to performance-based external attention caused a significant increase in the electrical activity of the right abdominal muscle during the concentric phase (P<0.001). However, there was no significant difference in the eccentric phase of the electrical activity of the right abdominal muscle between the two conditions (P=0.233). The results of the correlated t-test comparing the maximum force applied to the force plate before leaving the ground indicate the maximum knee angle in the outward phase of the movement. The results of the paired t-test showed that this force was significantly higher in the mechanics-based external focus condition than in the performance-based external focus condition (P=0.022), indicating that the maximum angle of the knee in the mechanics-based external focus condition exceeded that in the performance-based external focus condition.
4. Conclusion
These results indicate that performance-based external focus instructions lead to greater automaticity of movement and improved performance. However, they are not useful for improving movement mechanics. For this purpose, external focus instructions based on movement mechanics should be used. The decreased electrical activity with more effective results in the performance-based external focus condition is evidence of optimization of intramuscular coordination with the external focus. Therefore, it can be said that the focus of external attention based on mechanics leads to an increase in the electrical activity of the muscles of the lower limbs and is not suitable for skilled individuals in vertical jump movements, although it may be suitable for the initial learning efforts of beginners according to the learning stages.
Ethical Considerations
Compliance with ethical guidelines
There were no ethical considerations to be addressed in this research.
Funding
This research did not receive any grants from funding agencies in the public, commercial, or non-profit sectors.
Authors' contributions
All authors contributed equally to preparing the article.
Conflicts of interest
The authors declared no conflict of interest.
Type of Study: Research |
Subject:
Special
Received: 2024/01/7 | Accepted: 2024/01/27 | Published: 2024/02/2
Received: 2024/01/7 | Accepted: 2024/01/27 | Published: 2024/02/2
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