The Study of Corticospinal Excitability and Muscle Function Alignment following different Intensities of Postactivation Potentiation in Trained Subjects
Oral Presentation
Paper ID : 2026-SSRC
Authors
1دانشگاه خوارزمی
2دانشگاه شهید بهشتی
Abstract
Abstract
Research Aim: A change in corticospinal excitability can cause a change in neural output and ultimately a change in maximum force. Various training and non-training factors play a role in this neuromuscular response, and it seems that the intensity of the intervention is one of the effective factors in this regard. The present research was aimed at studying the responses of the central nervous system using TMS tool after several preparatory contractions with different intensities on muscle force.
Research method: 8 subjects (average age 24.8±2.70 years and weight 72.4±8.52 kg) performed the research protocol in three separate sessions with 20, 50 and 80% intensities of RMS MVC preparatory contractions in Hand Grip movement. The amount of corticospinal excitability, the electrical activity of the anterior superior ulnar muscle and the maximum force in the Hand Grip movement were measured several times after that and they compared with the repeated ANOVA statistical method.
Findings: The amplitude of Motor Evoked Potential (MEP) increased after preparatory contraction with intensity of 20%, but it decreased with increasing intensity of preparatory contraction to 50% and 80%, in such a way that there was a difference between intensity of 20% and 80% (P<0.001) and between 20% and 50% (P<0.041), while there was no significant difference between 50% and 80%. On the other hand, the amount of voluntary force measured by the maximum voluntary contraction and its electrical activity did not demonstrate any significant change (p>0.05) immediately and after 5 minutes’ contraction of the preparation.
Conclusion: It can be concluded that corticospinal excitability increases after low-intensity preparatory activity, but it decreases with increasing activity intensity to medium and high levels. However, none of the changes in cortical excitability were associated with changes in force and muscle electrical activity. Thus, there is a complex interplay between changes in supraspinal excitability following preparatory contractions and their effect on the individual's ability to improve or maintain force output, and so that needs further investigation.
Research Aim: A change in corticospinal excitability can cause a change in neural output and ultimately a change in maximum force. Various training and non-training factors play a role in this neuromuscular response, and it seems that the intensity of the intervention is one of the effective factors in this regard. The present research was aimed at studying the responses of the central nervous system using TMS tool after several preparatory contractions with different intensities on muscle force.
Research method: 8 subjects (average age 24.8±2.70 years and weight 72.4±8.52 kg) performed the research protocol in three separate sessions with 20, 50 and 80% intensities of RMS MVC preparatory contractions in Hand Grip movement. The amount of corticospinal excitability, the electrical activity of the anterior superior ulnar muscle and the maximum force in the Hand Grip movement were measured several times after that and they compared with the repeated ANOVA statistical method.
Findings: The amplitude of Motor Evoked Potential (MEP) increased after preparatory contraction with intensity of 20%, but it decreased with increasing intensity of preparatory contraction to 50% and 80%, in such a way that there was a difference between intensity of 20% and 80% (P<0.001) and between 20% and 50% (P<0.041), while there was no significant difference between 50% and 80%. On the other hand, the amount of voluntary force measured by the maximum voluntary contraction and its electrical activity did not demonstrate any significant change (p>0.05) immediately and after 5 minutes’ contraction of the preparation.
Conclusion: It can be concluded that corticospinal excitability increases after low-intensity preparatory activity, but it decreases with increasing activity intensity to medium and high levels. However, none of the changes in cortical excitability were associated with changes in force and muscle electrical activity. Thus, there is a complex interplay between changes in supraspinal excitability following preparatory contractions and their effect on the individual's ability to improve or maintain force output, and so that needs further investigation.
Keywords