A 6-month randomized controlled trial found that reducing sedentary behavior by 1 hour per day prevented a significant increase in back pain intensity (P = .030) in adults with metabolic syndrome and physical inactivity. The intervention, which primarily replaced sedentary time with physical activity, did not significantly affect pain-related disability or paraspinal muscle characteristics.

In the study, published in BMJ Open, researchers in Finland recruited 64 participants (mean age = 58 years, 42% male) who had metabolic syndrome and were physically inactive at baseline. The intervention group (n = 33) was instructed to reduce sedentary time by 1 hour daily, while the control group (n = 31) maintained usual behaviors.

The participants wore accelerometers to measure physical activity and sedentary time throughout the 6-month study period. Back pain intensity and pain-related disability were assessed using 10-cm Visual Analogue Scales, and the Oswestry Disability Index was used to evaluate back pain-related disability.

A subsample (n = 44) underwent imaging studies. Paraspinal muscle fat fraction was measured using two-point Dixon MRI, and muscle-specific insulin-stimulated glucose uptake was assessed via 18F-fluorodeoxyglucose positron emission tomography during hyperinsulinemic-euglycemic clamp.

Baseline characteristics:

• Mean body mass index (BMI): 31.5 kg/m² (intervention), 31.7 kg/m² (control).
• Mean body fat percentage: 43.1% in both groups.
• Median transversospinal fat fraction: 23.7% (intervention), 23.8% (control).
• Median erector spinae fat fraction: 17.5% (intervention), 18.0% (control).

Baseline accelerometry data:

• Mean sedentary time: 10.0 hours/day (intervention), 10.1 hours/day (control).
• Mean moderate-to-vigorous physical activity: 0.96 hours/day (intervention), 0.97 hours/day (control).

Among the key findings were:

• Back pain intensity remained unchanged in the intervention group but increased significantly in the control group (group × time P = .030).
• Pain-related disability increased over time in both groups (time P = .017), with no significant between-group differences.
• No significant changes were observed in Oswestry Disability Index scores or paraspinal muscle fat fraction and glucose uptake.
• Increased daily steps correlated with improved paraspinal muscle glucose uptake (rs = 0.39–0.41).

The intervention group reduced sedentary time by 40 minutes per day on average and increased moderate-to-vigorous physical activity by 20 minutes per day. Step count increased significantly more in the intervention group (from 5,326 to 8,632 steps/day) compared with the control group (from 5,150 to 6,749 steps/day).

Baseline median back pain intensity was low in both groups (0.3–0.5 cm on a 10-cm VAS). Pain intensity remained stable in the intervention group but increased significantly in the control group over 6 months. Although there were no statistically significant between-group differences in pain-related disability, changes in BMI and body fat percentage were positively correlated with increases in disability (Oswestry Disability Index, rs = 0.37 and rs = 0.26, respectively).

No significant intervention effects were observed for paraspinal muscle fat fraction or glucose uptake. However, the participants who increased daily steps by more than 2,500 showed improved paraspinal muscle glucose uptake compared with those with a step increase below 2,500 (group × time P = .033).

An intervention that reduces sedentary behavior by primarily replacing it with physical activity may prevent increases in back pain intensity in adults with metabolic syndrome and physical inactivity. Although no significant effects were observed on pain-related disability, improving daily step counts correlated with better muscle glucose uptake, warranting further investigation in the context of back pain and disability.

Competing interest disclosures can be found in the study.