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The purpose of this study is to investigate the magnitude of changes in biomarkers of exercise-induced muscle damage following an acute bout of eccentric exercise of the knee extensors performed on an isokinetic dynamometer. Moreover, these biomarkers will be assessed at different time points after the initial intervention, checking the repeated bout effect phenomenon.
Volunteers will visit the laboratory a total of two times. During the first visit, in all participants will be assessed indirect markers of exercise-induced muscle damage (i.e., peak torque, delayed-onset muscle soreness, range of motion, rate of force development), blood parameters (i.e., creatine kinase and c-Reactive Protein), and muscle oxygenation using near infrared spectroscopy. Afterwards, participants will perform an eccentric exercise protocol for the knee extensors consisting of 5 sets of 15 maximal-intensity repetitions at an angular velocity of 60°/s. The second visit will be at different time points between participant, where the indirect mauls damage biomarkers will be reassessed before and after the same isokinetic eccentric exercise (i.e., 5 sets of 15 maximal-intensity repetitions at an angular velocity of 60°/s).
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Initial bout of isokinetic eccentric exercise | Experimental | Isokinetic eccentric exercise will be performed, while before and 48h after a number of indirect biomarkers will be assessed |
|
| Subsequent bout of isokinetic eccentric exercise | Experimental | Isokinetic eccentric exercise will be performed, while before and 48h after a number of indirect biomarkers will be assessed |
|
| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Eccentric Exercise | Other | Eccentric exercise will be performed using an isokinetic dynamometer. It will be consisted of 5 set of 15 eccentric contraction of the knee extensors at an angular velocity of 60o/s. The intensity will be maximal voluntary. |
| Measure | Description | Time Frame |
|---|---|---|
| Delayed onset muscle soreness | Pain will be assessed at baseline (before the eccentric exercise bout) and again at 48 hours (2 days) after the eccentric exercise bout. | Baseline and 48 hours after the eccentric exercise bout. |
| Peak torque output | Peak torque will be assessed at baseline (before the eccentric exercise bout) and again at 48 hours (2 days) after the eccentric exercise bout. | Baseline and 48 hours after the eccentric exercise bout. |
| Range of Motion | The free pain range of motion will be assessed at baseline (before the eccentric exercise bout) and again at 48 hours (2 days) after the eccentric exercise bout. | Baseline and 48 hours after the eccentric exercise bout. |
| Muscle oxygenation | Using near infrared spectroscopy, the oxygenation of the knee extensors will be assessed at baseline (before the eccentric exercise bout) and again at 48 hours (2 days) after the eccentric exercise bout. | Baseline and 48 hours after the eccentric exercise bout. |
| Creatine kinase | Creatine kinase will be assessed at baseline (before the eccentric exercise bout) and again at 48 hours (2 days) after the eccentric exercise bout. | Baseline and 48 hours after the eccentric exercise bout. |
| Muscle thickness using ultrasound | Participants's knee extensors muscle thickness will be assessed at baseline (before the eccentric exercise bout) and again at 48 hours (2 days) after the eccentric exercise bout. | Baseline and 48 hours after the eccentric exercise bout. |
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Inclusion Criteria:
Exclusion Criteria:
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| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| Department of Physical Education and Sport Science, National and Kapodistrian University of Athens | Athens | Attica | 17237 | Greece |
| PubMed Identifier | Type | Citation | Retractions |
|---|---|---|---|
| 40570898 | Background | Bobotas V, Chatzinikolaou PN, Methenitis S, Doika E, Spiliopoulou P, Malliou VJ, Mpampoulis T, Terzis G, Geladas N, Paschalis V. The Effect of Exercise-Induced Muscle Damage on Muscle and Cerebral Oxygenation and Performance. Int J Sports Med. 2025 Dec;46(14):1049-1060. doi: 10.1055/a-2644-4923. Epub 2025 Jun 26. | |
| 36815692 | Background |
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Individual participant data will not be shared because participant consent did not include public data sharing and the dataset size increases re-identification risk.
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| Type | Includes Protocol | Includes SAP | Includes ICF | Document Label | Document Date | Document Uploaded Date | Document File Name |
|---|---|---|---|---|---|---|---|
| Prot_SAP_ICF | Yes | Yes | Yes | Study Protocol, Statistical Analysis Plan, and Informed Consent Form | Aug 31, 2025 | Feb 11, 2026 | Prot_SAP_ICF_000.pdf |
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| Methenitis S, Theodorou AA, Chatzinikolaou PN, Margaritelis NV, Nikolaidis MG, Paschalis V. The effects of chronic concentric and eccentric training on position sense and joint reaction angle of the knee extensors. Eur J Sport Sci. 2023 Jul;23(7):1164-1174. doi: 10.1080/17461391.2023.2184726. Epub 2023 Mar 18. |
| 22288788 | Background | Panayiotou G, Paschalis V, Nikolaidis MG, Theodorou AA, Deli CK, Fotopoulou N, Fatouros IG, Koutedakis Y, Sampanis M, Jamurtas AZ. No adverse effects of statins on muscle function and health-related parameters in the elderly: an exercise study. Scand J Med Sci Sports. 2013 Oct;23(5):556-67. doi: 10.1111/j.1600-0838.2011.01437.x. Epub 2012 Jan 31. |
| 18172668 | Background | Paschalis V, Nikolaidis MG, Giakas G, Jamurtas AZ, Owolabi EO, Koutedakis Y. Position sense and reaction angle after eccentric exercise: the repeated bout effect. Eur J Appl Physiol. 2008 May;103(1):9-18. doi: 10.1007/s00421-007-0663-9. Epub 2008 Jan 3. |
| 33156414 | Background | Margaritelis NV, Theodorou AA, Chatzinikolaou PN, Kyparos A, Nikolaidis MG, Paschalis V. Eccentric exercise per se does not affect muscle damage biomarkers: early and late phase adaptations. Eur J Appl Physiol. 2021 Feb;121(2):549-559. doi: 10.1007/s00421-020-04528-w. Epub 2020 Nov 6. |