The Role of Fatigue Associated With Strength Training in Exercise-induced Hypoalgesia

Official title

The Role of Fatigue Associated With Different Protocols of Strength Training in Exercise-induced Hypoalgesia: A Randomized Crossover Trial

Overview

Strength exercise is an active and dynamic activity that involves applying force against a resistance. This produces fatigue, seen as a reduced ability to apply force during and after the exercise, and perceived effort, which is a person's subjective feeling of how hard they are working. Strength exercise can also be used for therapy, as it has many benefits for different parts of the body. One of these is changing how the individual feels pain. It has been shown that doing strength exercises can reduce pain perception, a phenomenon called exercise-induced hypoalgesia (EIH), although the exact physical reasons and the amount of exercise needed to cause this effect are not yet known. One of the most studied exercises in this area is the leg extension machine. This is a specific exercise where the legs move freely (open kinetic chain) and the machine guides the movement, which helps keep things stable and limits the effect of other factors. It is usually used to strengthen and grow the muscles in the front of the thigh, especially the quadriceps, but it can also be used to study the effects on EIH. The main goal of this study is to see if fatigue and perceived effort during strength exercise are important for EIH to happen in healthy people. Participants will complete 3 sessions, at least 7 days apart. These will include a control session and 2 sessions designed to show different levels of fatigue. Before, during, and after the sessions, the investigators will measure pain sensitivity, isometric strength, and perceived effort. Also, there will be a test to find the maximum weight for 10 repetitions and several questionnaires to collect basic info (sex, age, height...), weekly physical activity, experience with strength training, and other factors like sleep quality, stress, and mood. All this information will be completely anonymous when the study results are shared.

Interventions

• Behavioral Seated leg extension machine: low fatigue
  Seated leg extension machine using 10RM external load for 6 sets of 5 repetitions with180 seconds rest between sets and a cadence of 1:2 second concentric:eccentric
• Behavioral Seated leg extension machine: high fatigue
  Seated leg extension machine using 10RM external load for 3 sets of 10 repetitions with 180 seconds rest between sets and a cadence of 1:2 second concentric:eccentric
• Behavioral Seated leg extension: control
  Seated leg extension machine using no external load for 6 sets of 5 repetitions with 180 seconds rest between sets and a cadence of 1:2 second concentric:eccentric

Primary outcome measures

• Pain pressure threshold [Time frame: Baseline, immediately post-exercise, 30 minutes after exercise]
• Pressure-evoked pain [Time frame: Baseline, immediately post-exercise, 30 minutes after exercise]
• RPE (Rating of Perceived Exertion) [Time frame: Immediately after each set of the training session]
• sRPE (Session rating of perceived exertion) [Time frame: Monitoring will take place 30 minutes after the final set, ensuring that the exertion from the last set does not interfere with the overall session RPE.]
• Repetitions in Reserve (RIR) [Time frame: Immediately after each set of the training session.]
• Muscle fatigue [Time frame: Baseline, immediately post-exercise, 30 minutes after exercise]

Secondary outcome measures (3)

• Kinematic measures [Time frame: During each set of the exercise intervention in all 3 sessions (3 or 6 sets depending on each arm). Total measurement time approximately 3 minutes during a single experimental session (as the device will stop recording during rest periods between sets).]
• Wellness [Time frame: Prior to each exercise session.]
• Fitness level [Time frame: Baseline (Day 1)]

Eligibility criteria

Inclusion criteria

• Healthy, asymptomatic subjects
• Being physically active

Exclusion criteria

• Experiencing episodes of acute pain in any part of the body.
• Having chronic pain or a recent history of chronic pain conditions considered resolved within the last 6 months.
• Having a serious illness or inability to perform moderate or intense physical activity.
• Having taken pain relievers, fever reducers, anti-inflammatory drugs (NSAIDs), steroids, opioids, or similar medications in the 24 hours before a session.
• Having consumed alcohol or other psychoactive substances, caffeine, or other stimulants in the 24 hours before a session.
• Having performed tiring physical activity or strength exercise in the 24 hours before a session.

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: Yes

Study design

Allocation

Randomized

Model

Crossover

Masking

Double blind

Primary purpose

Basic science

Study locations

Spain · 1 center

• Universidad Miguel Hernández — Alicante

Publications

• Hogge R, Mascheri M, Shurik D, Hanney WJ, Anderson AW. High-Fatigue Dynamic Resistance Exercise Induces Significant Hypoalgesia Effect. J Strength Cond Res. 2025 Feb 1;39(2):165-172. doi: 10.1519/JSC.0000000000004985. Epub 2024 Nov 26. PMID 39590221
• Vaegter HB, Jones MD. Exercise-induced hypoalgesia after acute and regular exercise: experimental and clinical manifestations and possible mechanisms in individuals with and without pain. Pain Rep. 2020 Sep 23;5(5):e823. doi: 10.1097/PR9.0000000000000823. eCollection 2020 Sep-Oct. PMID 33062901
• Wewege MA, Jones MD. Exercise-Induced Hypoalgesia in Healthy Individuals and People With Chronic Musculoskeletal Pain: A Systematic Review and Meta-Analysis. J Pain. 2021 Jan;22(1):21-31. doi: 10.1016/j.jpain.2020.04.003. Epub 2020 Jun 26. PMID 32599154

Identifiers

NCT: NCT07577622 · DPC.MDM.240801

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗