Acute Power Training Effects in Older Adults

Keywords

• Power Training
• Older Adults
• Aging
• Muscle Power
• Velocity Loss
• Resistance Training
• Neuromuscular Function
• Functional Performance
• Physiological Responses
• Exercise Fatigue

Lead sponsor

Hasselt University is the lead sponsor of 204 studies on the registry; 31 are open to participants now.

Study arms

• Experimental
  Low-Fatigue Power Training (10% velocity loss)

  Participants perform a single supervised session of power training on a pneumatic leg press, consisting of 4 sets. During the exercise, movement speed is continuously monitored. In this arm, the exercise set will be stopped when movement speed decreases by 10% compared with the fastest repetition, which corresponds to a low level of fatigue (small amount of repetitions).

  Behavioral: Power Training at Different Fatigue Levels

• Experimental
  Moderate Fatigue Power Training (30% velocity loss)

  Participants perform a single supervised session of power training on a pneumatic leg press, consisting of 4 sets. During the exercise, movement speed is continuously monitored. In this arm, the exercise set will be stopped when movement speed decreases by 30% compared with the fastest repetition, which corresponds to a moderate level of fatigue (more repetitions, performed closer to muscle failure).

  Behavioral: Power Training at Different Fatigue Levels

• Experimental
  Cluster-Set Power Training (10% Velocity Loss)

  Participants perform a single supervised session of power training on a pneumatic leg press. In this arm, the exercise is organized into 4 cluster sets. A cluster set consists of small groups of repetitions separated by short rest periods within the set. Participants will perform clusters of 3-4 repetitions with 20 seconds of rest between clusters. During the exercise, movement speed is continuously monitored. Each cluster will be performed within the range of 10% velocity loss compared with the fastest repetition, which corresponds to a low level of fatigue. Clusters will continue until the total number of repetitions matches the training volume (amount of total repetitions) reached in the 30% velocity loss condition. This design allows participants to complete a similar total training volume as in the moderate fatigue condition, while maintaining lower fatigue, enabling researchers to separate the effects of exercise volume from the effects of fatigue.

  Behavioral: Power Training at Different Fatigue Levels

Interventions

• BehavioralPower Training at Different Fatigue Levels

  Participants perform supervised power-training exercise on a pneumatic leg press. Each participant completes three exercise sessions, each separated by approximately one week. In each session, participants perform 4 sets of leg press exercise under different fatigue conditions: A) Exercise sets are terminated when movement velocity decreases by 10%. B) Exercise sets are terminated when movement velocity decreases by 30%. C) Exercise sets are terminated at 10% velocity loss, with total work matched to the 30% condition.

  Also known as: Power Training at Different Velocity Loss Thresholds, Power Training at Different Velocity-Based Training Doses

Primary outcomes

1. Maximum Voluntary Contraction (MVC)

   Maximum voluntary contraction (MVC) will be assessed to determine the maximum force-generating capacity of the leg extensors using an isokinetic dynamometer (Humac Norm). Simultaneously, muscle activity will be recorded using surface electromyography (EMG; Delsys EMG system). Primary outcome metric: Peak torque (Nm) obtained from three maximal isometric trials recorded on the dynamometer, combined with EMG amplitude (µV) to quantify muscle activation. Interpretation: Higher torque values indicate greater knee extensor strength. EMG amplitude reflects the level of muscle activation during maximal voluntary effort. Interpretation: Higher force values indicate greater leg muscle strength. EMG values indicate the level of muscle activation during the maximal effort.

   Time frame: Measurements will be taken before exercise (baseline), 5 minutes after each training session, and 24 hours after each session.

Secondary outcomes

1. Rate of Torque Development (RTD)

   Rate of torque development (RTD) will be assessed to determine how quickly participants can generate torque with their leg extensors. This will be measured using an isokinetic dynamometer (Humac Norm), which records joint torque, alongside surface electromyography (EMG; Delsys EMG system), which measures muscle activation. This parameter provides insight into neuromuscular responses to different levels of power training-induced fatigue. Metric: Peak rate of torque development (Nm/s) calculated from three maximal trials, together with EMG amplitude (µV). RTD will be calculated as the slope of the torque-time curve over a specified time interval (e.g., 0-100ms, 100-200 ms).

   Time frame: Measurements will be taken before exercise (baseline), 5 minutes after each training session, and 24 hours after each session.

2. Muscle Activity

   Muscle activity will be assessed by recording the electrical signals of the leg muscles during the leg press exercise using surface electromyography (sEMG; Delsys EMG system). This method enables quantification of muscle activation and fatigue-related changes in neuromuscular function. Surface electrodes will be placed on three key thigh muscles: the vastus lateralis, vastus medialis, and biceps femoris. Metric: EMG amplitude (µV), derived from the recorded electrical signals, representing the level of muscle activation during exercise.

   Time frame: Measurements will be taken before exercise (baseline), during exercise session (mean value across the full session), 5 minutes post exercise, and 24 hours post exercise (3 exercise sessions, 1 week apart)

3. Strength Training Data: Mean Movement Velocity

   Mean concentric movement velocity (meter per second (m/s)) recorded during each leg press (exercise) repetition using the Keiser A400 Leg Press.

   Time frame: During each exercise session (mean values across the full session) (3 Sessions ; ~1 week apart)

4. Strength Training Data: Power

   Mean mechanical power (Watts (W)) produced during each leg press repetition recorded by the Keiser A400 Leg Press.

   Time frame: During each exercise session (mean value across the full session) (3 Sessions ; ~1 week apart)

5. Strength Training Data: Total Number of Repetitions

   Total number of repetitions (count) completed during each exercise session on the leg press.

   Time frame: During each exercise session (mean value across the full session) (3 Sessions ; ~1 week apart)

6. Muscle Oxygenation

   Muscle oxygenation will be assessed to determine oxygen availability in the thigh muscle (vastus lateralis) during and after exercise using near-infrared spectroscopy (NIRS). In addition, a vascular occlusion test will be performed to evaluate muscle oxygen extraction and the recovery kinetics of oxygenation following transient blood flow restriction. Metric: Muscle oxygen saturation (%; e.g., SmO₂), as well as reoxygenation rate and amplitude following occlusion.

   Time frame: Baseline (pre-exercise), continuously during each exercise session, 5 minutes post-exercise, and 24 hours post-exercise (for each of the 3 sessions, 1 week apart)

7. Blood Lactate

   Small blood sample will be taken to measure lactate, in millimoles per liter analysed through standard laboratory tests, including Enzyme-Linked Immunosorbent Assay (ELISA).

   Time frame: Measurements will be taken at baseline and immediately post exercise session (3 sessions, 1 week apart)

8. Blood Gas

   A Small blood sample will be taken to measure blood gas levels (blood oxygen/carbon dioxide levels) using standard laboratory tests, including Enzyme-Linked Immunosorbent Assay (ELISA).

   Time frame: Measurements will be taken at baseline and immediately post exercise session (3 sessions, 1 week apart).

9. Creatine Kinase (CK)

   Small blood samples will be taken to measure creatine kinase (CK), an enzyme that increases in the blood when muscles are damaged or stressed. Metric: CK concentration in units per liter (U/L).

   Time frame: Measurements will be taken at Baseline and 24 hours after each exercise session.

10. Functional Performance: Five-Repetition Sit-to-Stand Test

    Five-Repetition Sit-to-Stand (5xSTS) test: Participants stand up from a chair repeatedly. An inertial measurement unit (DynaPort MoveTest, McRoberts, The Hague, NL) measures speed (meters per second (m/s)), movement duration (s) , and power (W).

    Time frame: Measurements will be taken at Baseline, immediate post exercise and 24 hours after each exercise session.

11. Functional Performance: Counter Movement Jump

    Countermovement Jump (CMJ): Participants jump vertically from a standing position. Jump height (cm), force (Nm), and power (W) are measured using KINVENT force plates.

    Time frame: Measurements will be taken at Baseline, immediate post exercise and 24 hours after each exercise session.

12. Functional Performance: Stair Ascent test

    Stair Ascent Test (SA): Participants climb a set of stairs while wearing an inertial measurement unit (DynaPort MoveTest, McRoberts, The Hague, NL), which measures speed (m/s), movement duration (s), distance (cm), and power (W).

    Time frame: Measurements will be taken at Baseline, immediate post exercise and 24 hours after each exercise session.

13. Functional Performance: 30-s Sit-to-Stand Test

    30-Second Sit-to-Stand (30sSTS) Tests: Participants stand up from a chair repeatedly. An inertial measurement unit (DynaPort MoveTest, McRoberts, The Hague, NL) measures speed (m/s), movement duration (s), and power (W).

    Time frame: Measurements will be taken at Baseline, immediate post exercise and 24 hours after each exercise session.

14. Perceived Exertion

    Perceived exertion will be assessed using the OMNI Resistance Exercise Scale (OMNI-RES). Participants will rate their level of effort after each exercise set during the leg press sessions. The scale ranges from 1 (no exertion at all) to 10 (maximum effort), with higher scores indicating greater perceived exertion.

    Time frame: Assessed after each exercise set during each exercise session (mean value across the full session) (3 Sessions ; ~1 week apart)

15. Delayed Onset Muscle Soreness (DOMS)

    Delayed onset of muscle soreness (DOMS) will be assessed using a Visual Analog Scale (VAS). Participants will rate perceived soreness in the leg muscles on a scale from 0 (no soreness) to 10 (worst possible soreness), with higher scores indicating greater muscle soreness.

    Time frame: Ratings will be collected at baseline, 24 hours after exercise, and 48 hours after exercise using a remote survey.

Individual participant data

Plan to share: Yes — Pseudonymazed participant data, including study measurements and outcomes, along with relevant supporting documents (e.g., study protocol, statistical analysis plan). Data will be shared via a Data Transfer Agreement (DTA). Access may be provided through a secure repository such as FAIRVault.

Supporting information: Study protocol, Statistical analysis plan, Informed consent form

Time frame: Beginning upon publication until 5 years after the publication of results.

Access criteria: Only qualified researchers affiliated with recognized academic or research institutions will be eligible. Researchers must submit a formal request describing the purpose and planned analyses. The research proposal must relate to legitimate scientific questions consistent with the original study aims. The proposed statistical methods must be clearly described. Researchers submit a data access request through the study's contact point or the FAIRVault platform. Once approved, they will sign a Data Transfer Agreement (DTA) before receiving access to the data. All requests will be reviewed by the study team or designated independent reviewers to ensure the research is appropriate, the data will be handled responsibly, and privacy protections are met.