The effect of six-week regular stretching exercises on regional and distant pain sensitivity

Key points

1. 01Daily bilateral hamstring stretching for six weeks raised pressure pain thresholds, meaning it took more pressure to feel pain.
2. 02The reduced pain sensitivity appeared not only at the stretched leg but also at a distant site (the shoulder), pointing to a body-wide nervous-system effect.
3. 03The hypoalgesic effect did not fade after four weeks of stopping stretching, contrary to what the researchers expected.
4. 04Range of motion improved by a small amount and was also retained after cessation.
5. 05This was a single-group study in 26 healthy adults with no control group, so the results cannot yet be applied directly to patients with chronic pain.

How it was conducted

Design

Single-blind longitudinal repeated-measures experiment, single group, no control

Participants

26 healthy adults (9 female), mean age 23.8 years, naive to experimental pain testing

Intervention

Daily bilateral static knee-flexor (hamstring) stretching, 7 days/week for 6 weeks; 30 s hold, 2 repetitions, then a 4-week cessation period

Primary outcome

Pressure pain thresholds at tibialis anterior (regional) and deltoid (distant), measured by handheld electronic algometer

Secondary outcome

Passive knee extension range of motion measured with a Biodex System 4 Pro isokinetic dynamometer

Analysis

One-way repeated-measures ANOVA with Bonferroni post hoc; alpha 0.05; 90% power to detect a 20% difference

What they found

• Regional pressure pain threshold (tibialis anterior) rose 36.7% from baseline to post-stretch (p = 0.003); main effect of time F[1, 25] = 13.337, p = 0.001.
• Distant pressure pain threshold (deltoid) rose 18.7% from baseline to post-stretch (p = 0.042); main effect F[1, 25] = 3.976, p = 0.025.
• Passive knee extension range of motion increased 3.6% from baseline to post-stretch (p = 0.002); main effect F[1, 25] = 11.666, p = 0.001.
• From baseline to post-cessation, distant pressure pain threshold rose 41.2% (p = 0.001) and regional rose 15.4% (p = 0.127), with range of motion up 3.6% (p = 0.005).
• No significant change between post-stretch and post-cessation for regional (p = 1.000), distant (p = 1.000), or range of motion (p = 1.000), indicating the effect was retained.
• Tibialis anterior pressure pain threshold values: 304.6 +/- 136.6 kPa at baseline, 391.1 +/- 132.3 kPa post-stretch, 412 +/- 174 kPa post-cessation.
• Change in regional and distant pain thresholds correlated weakly baseline to post-stretch (Rho = 0.479, p = 0.015) and moderately post-stretch to post-cessation (Rho = 0.597, p = 0.002).
• Adherence to the stretching program was 87.2% +/- 10.2%.

Limitations

• Single-group design with no control group, so improvements cannot be separated from natural variation, repeated-testing familiarity, or other factors.
• Small sample of 26 young, healthy adults naive to pain testing, limiting how far results extend to older people or patients in pain.
• COVID-19 delayed some final measurements, making the cessation period average 4.6 weeks rather than exactly 4 weeks.
• Regional pain testing site was chosen for practical reasons tied to the seated Biodex position, which may affect comparability.

Why it matters

For patients

If you are healthy, a simple daily stretching routine may make your body less sensitive to pain, with the benefit lingering even after a short break.

For clinicians

These findings add rationale for including regular stretching in rehabilitation aimed at reducing pain sensitivity, while recognizing the evidence comes from healthy volunteers without a control group.

For readers

This is an early, promising signal that stretching can produce a body-wide reduction in pain sensitivity, but it needs controlled trials in clinical populations before firm conclusions.