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Updated: Sep 25, 2025
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Ex vivo Mechanical Loading of Tendon
Published on: May 28, 2007
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Effects of isometric loading intensity on patellar tendon microvascular response
Jacob E Earp1,2, Haley Gesick1, Domenic Angelino2
1Department of Kinesiology, University of Connecticut, Storrs, Connecticut, USA.
Scandinavian Journal of Medicine & Science in Sports
|April 29, 2022
Summary
Moderate-intensity exercise, around 50% maximal voluntary isometric contraction (MVIC), maximally stimulates the patellar tendon
Area of Science:
- Sports Medicine
- Physiology
- Biomedical Engineering
Background:
- Acute increases in tendon blood flow and oxygenation (hyperemic response) are crucial for tendon recovery.
- The impact of varying loading intensities on the tendon's hyperemic response remains largely unexplored.
- Understanding this relationship is key for optimizing training protocols for tendon health.
Purpose of the Study:
- To investigate the acute effects of different isometric exercise intensities on the patellar tendon's hyperemic response.
- To determine if higher exercise loads beyond a certain threshold yield greater improvements in tendon blood flow and oxygenation.
- To identify the optimal loading intensity for eliciting a significant hyperemic response in the patellar tendon.
Main Methods:
- Thirteen participants performed isometric knee extensions at 25%, 50%, and 75% of their maximal voluntary isometric contraction (MVIC).
- Near-infrared spectroscopy (NIRS) was used to measure changes in total hemoglobin (THb) and oxygenated hemoglobin (HbO2) in the patellar tendon.
- Exercise bouts were separated by 20-minute recovery periods and conducted in a randomized, counterbalanced order.
Main Results:
- Oxygenated hemoglobin (HbO2) significantly increased at 50% and 75% MVIC, but not at 25% MVIC.
- Total hemoglobin (THb) increased significantly at 50% MVIC, but not at 25% or 75% MVIC.
- A significant increase in THb, HbO2, and deoxygenated hemoglobin (HHb) was observed when increasing load from 25% to 50% MVIC, with no further significant changes between 50% and 75% MVIC.
Conclusions:
- A loading threshold of approximately 50% MVIC appears sufficient to fully achieve the patellar tendon's hyperemic response.
- Resistance training intensities above 50% MVIC may not provide additional benefits for the tendon's microvascular response.
- Moderate loading intensities are likely adequate for stimulating the patellar tendon hyperemic response believed to promote tendon healing.
