Upper and Lower Extremity Exercise and Exercise-Induced Hypoalgesia in Knee Osteoarthritis

University of Texas, El Paso60 enrolled

Overview

The objective of the study is to explore the effects of arm exercise (UE, arm ergometer) vs. leg exercise (LE, cycling ergometer) on exercise-induced hypoalgesia (EIH), central pain mechanisms and knee pain in people with knee osteoarthritis (OA). Furthermore, we will explore relations of socioeconomic status, racial discrimination, acculturative stress, and autonomic function to exercise effects on EIH, central pain mechanisms, and knee pain. This will be a pilot randomized cross-over study where all participants undergo Day 1 (baseline assessments), Day 2 (UE or LE), and Day 3 (UE or LE).

This will be a pilot randomized cross-over study. Major exclusion criteria will be conditions that have risks with exercise or affect pain assessments. Once enrolled, all participants will undergo 3 laboratory visits, each separated at least by a week as a wash-out period: day 1, baseline assessment; day 2, randomized to either upper extremity exercise (UEE) (i.e., arm ergometer) or knee exercise (KE) (i.e., cycling ergometer); and day 3, UEE or KE alternative to the exercise on day 2. UEE will be an arm-ergometer and KE will be a cycle-ergometer in which participants will undergo the first 5 minutes at an intensity of 50% heart rate reserve (HRR)(warm-up period), followed by 20 minutes at 70% HRR. Heart rate will be monitored during the exercise. On day 1, we will collect participant characteristics data. We will also collect data related to race/ethnicity, racial discrimination, acculturative stress, physical activity level, heart rate variability (HRV) parameters (measures of autonomic function). Further, participants will undergo knee pain assessment with a 20-meter walk, quantitative sensory testing (QST) measures of pressure pain threshold (PPT), temporal summation (TS), and conditioned pain modulation (CPM) as surrogate measures of central pain mechanisms. On Days 2 and 3 we will collect knee pain, QST, and EIH data before and immediately after the exercise.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

Eligibility

Sex: ALLMin age: 45 YearsMax age: 90 YearsHealthy volunteers:

Medical Language ↔ Plain English

Participants with knee OA (Target n=40) Inclusion Criteria: We will recruit participants with knee OA, using the National Institute for Health and Care Excellence's clinical diagnostic criteria, which does not require radiographs. The clinical diagnostic criteria include: * age ≥45 * activity-related knee pain * either no morning joint-related stiffness or stiffness that lasts ≤ 30 minutes. * knee pain at least 4 on a 0-10 pain scale * knee pain as a chief complaint if having multiple pain * understand English Exclusion Criteria: * peripheral neuropathy or other sensation loss on the body sites for pain measurements (i.e., the wrist, knee, the forearm) * use of medical devices electrically active (e.g., pacemaker) * chronic use of opioids * pregnant women * serious and uncontrolled concomitant disease, including cardiovascular, nervous system, pulmonary, renal, hepatic, metabolic, hormonal, endocrine, gastrointestinal or epileptic disease * rheumatoid arthritis, ankylosing spondylitis, and any neurological disorders that prevent the study procedure * cognitive impairment * history of a knee replacement surgery * inability to perform exercise due to severe pain or other symptoms * any intervention procedures for knee pain in the last 3 months Inclusion and exclusion criteria for pain-free controls (Target n = 20) Pain-free controls are not having a pain-related medical condition. They have to speak and understand English. Pain-free controls are excluded if they had experienced a pain episode, caused by musculoskeletal injury or otherwise in the previous 3 months.

Outcomes

Primary Outcomes

Changes in pressure pain thresholds (Measure of exercise-induced hypoalgesia)

Pressure pain thresholds (PPT) will be assessed at the wrist and patella. PPT being assessed at a remote body site (e.g., wrist) is to measure central pain sensitivity while PPT being assessed at the location of pain (i.e., knee, patellae) is to assess peripheral pain sensitivity with or without central pain sensitivity. PPT will be assessed using a handheld pressure algometer with 1 cm2 rubber tip. PPT will be defined as the point at which the participant verbally indicated that the pressure first changed to slight pain. A lower PPT value (Kgf) represents greater pain sensitivity. PPT will be assessed 3 times at each location and averaged. Furthermore, changes in PPT after exercise has been used to assess the degree of exercise-induced hypoalgesia (EIH). When PPT values increase after the exercise, it indicates a reduction of pain sensitivity and, therefore, an effect of EIH.

Time frame: Day 1: PPT will be assessed twice. PPT assessment --> 25 minutes of waiting --> PPT assessment; Time frame of Days 2 and 3 will be the same except 25 minutes of waiting time. It will be 25 minutes of exercise (either AE or LE) on Days 2 and 3

Mechanical temporal summation

Temporal summation (TS) is a sensitive measurement of central pain sensitivity. Investigators will assess TS using a standard set of weighted probes from 64-512 mN. Participants will rate the pain experienced by each successive weighted probe being touched on the skin of the wrist until a pain rating of ≥ 4/10 is achieved. The selected probe will be then applied at a frequency of 1 Hz for 10 seconds on the wrist. Participants will provide a pain rating at the completion of the train of 10 stimulations and 15 seconds post-stimulation. TS will be defined as the difference between the highest post-stimulation pain rating and the initial pain rating. A post-stimulation pain rating greater than the initial pain rating will be considered to be reflective of an increase in central pain sensitivity.

Time frame: Day 1: TS will be assessed twice. TS assessment --> 25 minutes of waiting --> TS assessment; Time frame of Days 2 and 3 will be the same except 25 minutes of waiting time. It will be 25 minutes of exercise (either AE or LE) on Days 2 and 3

Conditioned pain modulation

Conditioned pain modulation (CPM) evaluates the adequacy of the descending pain modulatory pathways, which contributes to central pain sensitivity. Investigators will assess CPM using PPT as the test stimulus (PPT1) at the wrist as described above, with forearm ischemia using a blood pressure cuff as the conditioning stimulus. Briefly, the blood pressure cuff applied to the contralateral arm will be inflated to 10mm Hg above systolic pressure. The participant will be then instructed to perform hand grip squeezes until pain of at least 4/10 occurs in the contralateral arm. PPT will be then reassessed at the wrist 3 times and averaged (PPT2). Percent efficiency of CPM (%CPM) was computed as PPT2/PPT1, multiplied by 100; %CPM ≤ 100 indicates inefficient CPM.

Time frame: Day 1: CPM will be assessed twice. CPM assessment --> 25 minutes of waiting --> CPM assessment; Time frame of Days 2 and 3 will be the same except 25 minutes of waiting time. It will be 25 minutes of exercise (either AE or LE) on Days 2 and 3

Knee pain

We will assess changes in knee pain with a 20 meter walk using a 0-10 numeric rating scale where 0 indicates no knee pain and 10 indicates the worst knee pain.

Time frame: Day 1: knee pain will be assessed twice. Knee pain assessment --> 25 minutes of waiting --> knee pain assessment; Time frame of Days 2 and 3 will be the same except 25 minutes of waiting time. It will be 25 minutes of exercise (either AE or LE) on Days 2

Secondary Outcomes

Racial discrimination

Racial discrimination will be assessed with the Perceived Experiences of Discrimination Questionnaire-Community Version (PEDQ-CV). This is a reliable and valid 17-item survey that assesses experiences of racialized discrimination.