Muscle Stretching - the Potential Role of Endogenous Pain Inhibitory Modulation on Stretch Tolerance

Study Overview
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Brief Summary
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This study investigates the influence of a remote, painful stimulus on stretch tolerance. Half of the participants will receive a conditioning painful stimulus following static stretching while the other half will rest quietly.

Detailed Description
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The effect of stretching on joint range of motion is primarily related to changes in the tolerance to stretch, but the mechanisms underlying this change are still largely unknown. The nervous system has an inbuilt ability to modulate the perceived magnitude of afferent noxious stimuli via supraspinally mediated endogenous pain inhibition or facilitation and by engaging endogenous mechanisms pain tolerance in healthy individuals is known to increase. Thus increasing the tolerance to pain could potentially increase range of motion following stretching.

Official Title
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Muscle Stretching - the Potential Role of Endogenous Pain Inhibitory Modulation on Stretch Tolerance

Conditions
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Muscle Stretching Exercises, Pain Threshold

Intervention / Treatment
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* Other: Cold pressor test


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Eligibility for participation included the absence of any pain or other conditions that might affect the somatosensory system. Exclusion Criteria: Substance abuse, History of neurological or mental disabilities Lack of ability to comply with instructions Delayed onset of muscle soreness.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 45 Years

Sexes Eligible for Study
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Male

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: A sample of convenience was recruited for this cross-sectional study. Participants were randomly assigned to a pain group or a control group using counterbalanced block randomization. Passive knee extension range of motion was measured three consecutive times with five-minute intervals between measurements. Both groups underwent a static stretch protocol consisting of two bouts of thirty-second constant-angle static stretching of the knee flexors with a one-minute rest between bouts. Subjects were instructed to keep the limb relaxed as the lower leg was passively moved towards extension. Following stretching, the post-stretch measurement was performed. Finally, subjects in the pain group were instructed to immerse their non-dominant hand into a container with circulating water at 1˚C to 4˚C and keep it there for 2 minutes. A Biodex system 4 pro dynamometer was used to quantify range of motion and passive resistive torque. Muscle activity was recorded as surface electromyography.
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Experimental pain group<br>subjects in the pain group were instructed to immerse their non-dominant hand into a container with circulating water at 1˚C to 4˚C and keep it there for 2 minutes. They were instructed to immerse it to wrist-level and keep the hand open. | Other: Cold pressor test<br>* Participants placed their non-dominant hand into cold water for 2 minutes<br>|
| No Intervention: Control group<br>Participants rested in a seated position for 5 minutes. | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Knee extension range of motion | Passively induced knee extension range of motion was measured usind the Biodex system 4 pro isokinetic dynomometer | Passive knee extension range of motion was measured at baseline | 
| Change in knee extension range of motion between baseline and post stretch. | Changes in passively induced knee extension range of motion was measured using the Biodex system 4 pro isokinetic dynomometer | Changes in passive knee extension range of motion were measured 5 minutes after baseline measures following stretching | 
| Changes in knee extension range of motion between post stretch and post pain. | Changes in passively induced knee extension range of motion was measured using the Biodex system 4 pro isokinetic dynomometer | Changes in passive knee extension range of motion were measured 5 minutes after post stretch measures following intervention. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Surface electromyography measures of muscle activity | Muscle activity during the passive knee extension motion were measured using SEMG. | Muscle activity during the passive knee extension motion was measured at baseline | 
| Changes in surface electromyography measures of muscle activity between baseline and post stretch measures. | Changes in muscle activity during the passive knee extension motion were measured using SEMG. | Changes in muscle activity during the passive knee extension motion were measured 5 minutes after baseline measures following stretching. | 
| Changes in surface electromyography measures of muscle activity between post stretch and post pain measures. | Changes in muscle activity during the passive knee extension motion were measured using SEMG. | Changes in muscle activity during the passive knee extension motion were measured 5 minutes after post stretch measures following intervention. | 
| Passive resistive torque using the Biodes system 4 pro. | Passive resistive torque during the passive knee extension motion was measured using the Biodex system 4 pro isokinetic dynamometer. | Passive resistive torque during the passive knee extension motion was measured at baseline. | 
| Changes in passive resistive torque measured using the Biodex system 4 pro between baseline and post stretch measures. | Changes in passive resistive torque during the passive knee extension motion was measured using the Biodex system 4 pro isokinetic dynamometer. | Changes in passive resistive torque during the passive knee extension motion was measured 5 minutes after baseline measures following stretching. | 
| Changes in passive resistive torque measured using the Biodex system 4 pro between post stretch and post pain measures. | Changes in Passive resistive torque during the passive knee extension motion was measured using the Biodex system 4 pro isokinetic dynamometer. | Passive resistive torque during the passive knee extension motion was measured 5 minutes after post stretch measures following intervention. | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Stretch tolerance, Range of Motion