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This study investigates the acute and 24-hour recovery effects of localized muscle fatigue on the viscoelastic properties of the medial gastrocnemius (MG) muscle and vertical jump performance. The research aims to quantify the changes in muscle stiffness, tone, and elasticity immediately after a standardized fatigue protocol and to monitor the recovery of these parameters 24 hours later. Additionally, the study evaluates the impact of fatigue on explosive power, measured by countermovement jump (CMJ) height, across these time points.
Participants undergo a structured experimental procedure to evaluate the changes across three time points:
Baseline Assessment: Passive muscle tone (Hz), stiffness (N/m), and elasticity (logarithmic decrement) of the medial gastrocnemius (MG) are measured using the MyotonPRO device. Initial vertical jump height is determined through countermovement jump (CMJ) tests.
Fatigue Protocol & Acute Assessment: Participants perform standardized standing calf raises until task failure. Immediately following the protocol, MG myotonometric properties and CMJ performance are re-measured to determine the acute fatigue-induced changes.
24-Hour Follow-up: Participants return to the laboratory exactly 24 hours later. All measurements (MyotonPRO and CMJ) are repeated to assess the return to baseline levels and the recovery status of the muscle-tendon unit.
The statistical analysis focuses on the differences between baseline, post-fatigue, and 24-hour recovery measurements.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Gastrocnemius Fatigue Group | Experimental | Participants in this arm undergo a standardized localized muscle fatigue protocol for the plantar flexors. This involves performing repetitive standing calf raises at a constant tempo of 60 beats per minute until task failure. Muscle myotonometric properties (tone, stiffness, elasticity) and vertical jump performance (CMJ) are measured at baseline, immediately post-fatigue, and 24 hours later to evaluate acute changes and recovery. |
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| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Isometric Plantar Flexion Fatigue Protocol | Device | Participants undergo a localized isometric fatigue protocol in a supine position with their feet placed against a solid wall. They perform maximal isometric plantar flexion pushing against the wall. The protocol continues until the participant reports a score of 8 or higher (indicating 'very strong' to 'maximal' exertion) on the Borg CR-10 Scale. Task failure is also confirmed by the inability to maintain the required isometric pressure or foot position despite verbal encouragement. This ensures a standardized level of subjective and objective muscle fatigue across all participants. |
| Measure | Description | Time Frame |
|---|---|---|
| Muscle Stiffness of the Medial and Lateral Gastrocnemius | Evaluation of the intrinsic mechanical stiffness of the medial (MG) and lateral (LG) gastrocnemius muscles using myotonometry. Higher values indicate greater stiffness. Measured in Newtons per meter (N/m). | Baseline, immediately post-fatigue (Post-0), and 24 hours post-fatigue (Post-24h) |
| Measure | Description | Time Frame |
|---|---|---|
| Vertical Jump Performance (Jump Height) | Assessment of explosive power using the Countermovement Jump (CMJ) height measured on a digital force platform. Measured in centimeters (cm). | Baseline, immediately post-fatigue (Post-0), and 24 hours post-fatigue (Post-24h) |
| Countermovement Jump Phase Durations (Braking and Eccentric) |
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Inclusion Criteria:
Exclusion Criteria:
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| Name | Affiliation | Role |
|---|---|---|
| Ali Ä°lez, PhD Can | VU University of Amsterdam | Principal Investigator |
| Nergiz Batur, PhD Can | Galata University | Principal Investigator |
| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| Istanbul Beykent University | Istanbul | Turkey (Türkiye) |
| PubMed Identifier | Type | Citation | Retractions |
|---|---|---|---|
| 42210407 | Derived | Sahbaz Y, Ilez A, Batur N. Asynchronous recovery of medial and lateral gastrocnemius mechanical properties and jump performance following localized plantar flexor fatigue. BMC Sports Sci Med Rehabil. 2026 May 28. doi: 10.1186/s13102-026-01774-x. Online ahead of print. |
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Individual participant data will not be publicly available to protect participant privacy. However, de-identified aggregate data and study protocols may be shared upon reasonable request to the corresponding author.
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A single-group, repeated measures design where all participants undergo a fatigue protocol, with measurements taken at three time points: baseline, immediately post-fatigue, and 24 hours later.
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Masking is not possible due to the nature of the physical fatigue protocol.
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Temporal analysis of the jumping strategy, specifically the duration of the eccentric and braking phases. Measured in milliseconds (ms). |
| Baseline, immediately post-fatigue (Post-0), and 24 hours post-fatigue (Post-24h) |
| Dynamic Balance Performance (Y-Balance Test) | Measurement of dynamic postural control in three directions (Anterior, Posteromedial, Posterolateral). Reach distances are normalized to leg length. Measured in percentage of leg length (%LL). | Baseline, immediately post-fatigue (Post-0), and 24 hours post-fatigue (Post-24h) |