Does aerobic exercise effect pain sensitisation in individuals with musculoskeletal pain? A systematic review

Key points

1. 01All 11 included studies reported a hypoalgesic effect of aerobic exercise on pain sensitisation.
2. 02Median improvement in pressure pain thresholds or pain ratings across studies was 10.6% (minimum 2.2%, maximum 24.1%).
3. 03Walking and cycling at submaximal intensity (50-75% maximal or 40-85% heart rate reserve) for 4-60 minutes appeared sufficient to achieve a hypoalgesic effect.
4. 04Individuals with abnormal conditioned pain modulation or those who experienced increased pain during exercise may not benefit to the same extent.
5. 05High clinical heterogeneity between studies prevented a meta-analysis; results are based on a best-evidence synthesis only.

How it was conducted

Design

Systematic review conducted according to 2020 PRISMA guidelines; best-evidence synthesis used due to high clinical heterogeneity preventing meta-analysis

Studies included

11 studies: 7 experimental repeated-measures studies and 4 randomised controlled trials

Databases searched

OVID MEDLINE, OVID Embase, OVID EBM Reviews Cochrane Central Register, OVID PsycINFO, CINAHL, and SPORTDiscus from inception to 26 March 2021 (13,190 studies identified)

Participants

Adults with musculoskeletal pain including chronic low back pain (5 studies), chronic musculoskeletal pain (3 studies), neck pain (2 studies), and knee osteoarthritis (1 study); sample sizes ranged from 8 to 96 per study

Intervention

Aerobic exercise (walking, cycling, Nordic walking, or participant-preferred aerobic activity) at submaximal intensity

Primary outcome

Pain sensitisation measured via pressure pain thresholds (PPT) or thermal pain thresholds/ratings

What they found

• All 11 studies reported a hypoalgesic effect of aerobic exercise; median (minimum, maximum) improvement in pain sensitisation was 10.6% (2.2%, 24.1%) post-exercise.
• Vaegter et al. (2016) found widespread PPTs increased post-exercise in both high pain sensitivity (272.8 to 319.1 kPa; 17.0% increase) and low pain sensitivity (574.7 to 646.3 kPa; 12.5% increase) groups (p<0.05).
• Hoffman et al. reported mean pressure pain ratings significantly lower at 2 min post-exercise (62(27) mm) compared with pre-exercise (79(12) mm) (p<0.05), with the effect sustained at 32 min post-exercise.
• Ote Karaca et al. (RCT) reported a significant increase in PPT sum in the exercise group from 19.9(6.1) to 22.0(6.3) kg/cm compared with the control group (20.7(5.4) to 20.9(6.7)) (p=0.023); a 10.6% increase.
• Nielsen et al. (RCT) reported increased PPTs at the tibialis anterior site after 10 weeks of aerobic exercise (311(113) to 386(107) kPa; 24.1% increase; p<0.01) but no significant increase at the trapezius site.
• Fingleton et al. found knee OA patients with abnormal conditioned pain modulation showed a decrease in PPTs (168.9(43.1) to 152.8(52.3) kPa) while those with normal conditioned pain modulation showed an increase (184.3(58.1) to 205.7(76.1) kPa; P<0.05).
• Bruehl et al. (RCT) reported a significant main effect of intervention group on MPQ-SF Total pain rating (F(1,77)=5.80, P=0.018, h2=0.064); exercise group showed slightly improved pain responsiveness whereas control group reported an increase over time.
• Sitges et al. reported lower pressure pain-intensity ratings (1.584 vs 2.865, p<0.001) and lower PPTs (p<0.001) after treadmill walking intervention compared with before.
• Kocur et al. reported significant PPT increases after 12 weeks of Nordic walking at descending trapezius (1.32(0.5) to 1.99(0.6) kg/cm, p=0.002), infraspinatus (1.63(0.6) to 2.93(0.8), p=0.001), and latissimus dorsi (1.66(0.6) to 2.21(0.5), p=0.02), with no improvement in control group.
• Risk of bias was low in 2 studies, moderate in 6 studies, and high in 3 studies; the 3 RCTs other than Ote Karaca had high risk of bias due to absence of allocation concealment and blinding.
• Clinical heterogeneity score was 17 out of 22 on the CDIM tool, indicating high clinical heterogeneity among the trials.

Limitations

• Only 11 studies with small sample sizes (8-96 participants) were included, and high clinical heterogeneity prevented meta-analysis, limiting the strength of conclusions.
• Three of the four RCTs had high risk of bias owing to lack of allocation concealment and blinding of participants and personnel.
• No established minimal clinically important difference (MCID) exists for pain sensitisation outcomes, making the clinical significance of the 10.6% median improvement uncertain.
• Studies were limited to English-language publications, potentially introducing language bias; also, longer-term follow-up data and broader outcomes such as disability and quality of life were largely absent.

Why it matters

For patients

People with chronic musculoskeletal pain such as low back pain or neck pain may experience meaningful reductions in pain sensitivity from regular aerobic exercise like walking or cycling, even at moderate intensities.

For clinicians

Submaximal aerobic exercise (walking or cycling at 50-85% maximum heart rate or heart rate reserve) for at least 4 minutes per session can be recommended as part of pain management, but clinicians should be aware that patients with abnormal conditioned pain modulation or those who experience pain during exercise may have a blunted or absent response.

For readers

This is a preliminary systematic review with high heterogeneity and modest-quality evidence; while the direction of effect is consistently positive, high-quality RCTs targeting specific musculoskeletal subgroups are still needed before firm clinical guidance can be issued.