The Effects of Intensity on Exercise-Induced Hypoalgesia During a Knee Extension Exercise

Study Overview
=================
Brief Summary
-----------------
The primary purpose of this study is to to compare immediate changes in pressure pain threshold at the exercising muscle (quadriceps) and a non-exercising muscle (upper trapezius) during low and high weight knee extension exercise. Participants will attend one session that consists of pain sensitivity testing, completion of pain-related psychological questionnaires, and random assignment to one of three interventions: 1) knee extension exercise with a high weight, 2) knee extension exercise with a low weight, or 3) quiet rest.

Official Title
-----------------
The Effects of Intensity on Exercise-Induced Hypoalgesia During a Knee Extension Exercise

Conditions
-----------------
Healthy

Intervention / Treatment
-----------------
* Other: Seated knee extension exercise


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Pain-free 18-60 years old Participant can appropriately perform the knee extension exercise (assessed during screening) Exclusion Criteria: Non-English speaking Regular use of prescription pain medications Current or history of chronic pain condition Currently taking blood-thinning medication Systemic medical condition known to affect sensation, such as uncontrolled diabetes or neurological conditions Any contraindication to the application of ice, such as: uncontrolled hypertension, cold urticaria, cryoglobulinemia, paroxysmal cold hemoglobinuria, circulatory compromise Known presence of cardiovascular, pulmonary, or metabolic disease Current use of tobacco products Not physically ready to exercise without a medical exam as indicated by the Physical Activity Readiness Questionnaire Plus (PAR-Q+) Surgery, injury, or fracture to the lower back or lower extremity within the past 6 months

Ages Eligible for Study
-----------------
Minimum Age: 18 Years
Maximum Age: 60 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
Accepts Healthy Volunteers

Study Plan
=================
How is the study designed?
-----------------

Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: High Intensity Exercise<br>Participants will complete a knee extension exercise with weight equivalent to 75% of their 1-repetition maximum for 3 sets of 10 repetitions. | Other: Seated knee extension exercise<br>* Participants will be seated in a resistance exercise machine. Weight corresponding to the assigned group will be added to the machine. Participants will extend the dominant knee for 3 sets of 10 repetitions.<br>|
| Experimental: Low Intensity Exercise<br>Participants will complete a knee extension exercise with weight equivalent to 30% of their 1-repetition maximum for 3 sets of 10 repetitions. | Other: Seated knee extension exercise<br>* Participants will be seated in a resistance exercise machine. Weight corresponding to the assigned group will be added to the machine. Participants will extend the dominant knee for 3 sets of 10 repetitions.<br>|
| No Intervention: Quiet Rest<br>Participants will sit quietly for two minutes, three times. | |

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Pressure Pain Threshold | A digital pressure algometer will be applied to the quadriceps and upper trapezius for two trials each. Participants are instructed to say stop or pain so the stimulus can be terminated when the sensation first transitions from pressure to pain (pain threshold). Participants will rate the pain experienced during the threshold testing using a 101-point numeric pain rate scale (NPRS) anchored with 0= no pain to 100= the most intense pain sensation imaginable immediately following each testing time. | Change from baseline to immediately after the exercise | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Conditioned Pain Modulation | Pressure pain threshold after an cold water immersion task will be measured. | Change from baseline to immediately after the exercise. |