Flexion Relaxation Ratio Not Responsive to Acutely Induced Low Back Pain from a Delayed Onset Muscle Soreness...

Area of Science:

• Biomechanics
• Musculoskeletal Health
• Pain Management

Background:

• The flexion relaxation ratio (FRR) is a proposed indicator of muscular function in individuals experiencing low back pain (LBP).
• Investigating the responsiveness of FRR to experimentally induced acute LBP is crucial for understanding its clinical utility.

Purpose of the Study:

• To determine if the flexion relaxation ratio (FRR) is sensitive to acute low back pain (LBP) elicited through a delayed onset muscle soreness (DOMS) protocol.

Main Methods:

• Fifty-one healthy volunteers underwent a DOMS protocol to induce LBP.
• Measurements included pain intensity, trunk flexion range of motion (ROM), and passive straight leg raise (SLR) at baseline, 24, and 48 hours post-DOMS.
• Participants were grouped by pain intensity, and changes in FRR, trunk flexion ROM, and SLR ROM were analyzed.

Main Results:

• No significant differences in FRR were observed between pain groups or over time.
• A significant decrease in trunk flexion ROM was noted in the higher pain group compared to the minimal pain group.
• Passive straight leg raise (SLR) ROM showed no significant decrease over time.

Conclusions:

• The flexion relaxation ratio (FRR) does not appear to be responsive to acute low back pain (LBP) resulting from a DOMS protocol.
• The clinical utility of FRR may be limited for assessing acute LBP of muscular origin.