Immediate effects of conventional and burst tens combined with cryotherapy in chronic non-specific low back pain: a randomized controlled trial

Background Chronic nonspecific low back pain (CNLBP) is a recurrent problem. The association between Transcutaneous Electrical Nerve Stimulation (TENS) and cryotherapy appears as an option in the treatment of painful symptoms caused by this dysfunction. Objective: To investigate the immediate effects of TENS, alone or combined with cryotherapy, on pain in individuals with CNLBP.Methods 120 individuals with CNLBP were randomized into six groups: placebo TENS (PT), burst TENS (BT: 100 Hz modulated at 4 Hz, 200 μs), conventional TENS (CT: 100 Hz, 100 μs), cryotherapy alone (Cryo), cryotherapy plus conventional TENS (CryoCT), and cryotherapy plus burst TENS (CryoBT). Participants received a single 25-minute intervention followed by 25 minutes of rest. Pain intensity was measured using the Numerical Pain Rating Scale (NPRS), and pressure pain threshold (PPT) was assessed by algometry over the lumbar paravertebral muscles. Assessments were performed at baseline, immediately post-intervention, and after 25 minutes.Results Both CryoCT and CryoBT significantly reduced pain intensity immediately post-intervention compared to the other groups (p = .009 to p = .047 and d = 0.61 to d = 1.05). However, only CryoBT maintained lower pain intensity after 25 minutes (p = .005 to p = .049 and d = 0.74 to d = 1.33). This group also demonstrated greater increases in PPT immediately and 25 minutes after the intervention compared to most other groups (p < .001 to p = .049 and d = 0.54 to d = 0.87).Conclusion A single session of burst TENS combined with cryotherapy produced greater immediate and short-term improvements in pain intensity than isolated techniques or conventional TENS combinations. Although statistical PPT improvements were observed, they lacked clinical meaningfulness. These findings suggest that, by integrating both modalities within a single protocol, CryoBT remains a promising, time-optimizing, and practical analgesic strategy for individuals with CNLBP.