Effectiveness of monopolar diathermy by radiofrequency combined with exercise in patients with chronic low back pain: A randomized clinical trial

Abstract

Background

Chronic low back pain can severely affect quality of life. While several treatments are available, the combination of therapies often results in better outcomes.

Objective

This study delves into the comparative effectiveness of combining monopolar dielectric diathermy radiofrequency (MDR) with supervised therapeutic exercise against the latter treatment alone.

Methods

A randomized single-blind controlled trial was conducted. The intervention group ( $(n = 30)$ 30) received MDR with supervised therapeutic exercises for eight weekly sessions for four weeks. The control group ( $n =$ 30) received only the same exercise protocol. The following self-report measures were assessed before the first treatment session, at four, and 12 weeks: disability, pain, kinesiophobia, quality of life, sleep quality, emotional distress, isometric trunk strength, and trunk flexion range.

Results

Repeated ANOVA measures revealed significant time*group interactions for the McQuade test ( $p =$ 0.003), the physical role ( $p =$ 0.011), vitality ( $p =$ 0.023), social function ( $p =$ 0.006), and mental health subscales ( $p =$ 0.042). Between-group analyses showed significant differences for all outcomes at each follow-up: RMDQ (post-treatment, $p =$ 0.040), ODI (post-treatment and 12-week, $p =$ 0.040), VAS ( $p <$ 0.001), TSK ( $p <$ 0.001), and McQuade Test ( $p <$ 0.020).

Conclusion

The combination of diathermy radiofrequency with supervised therapeutic exercise significantly surpasses the efficacy of supervised therapeutic exercise alone, showcasing improvements in pain, disability, kinesiophobia, lumbar mobility in flexion, and overal quality of life in patients with chronic low back pain.

Keywords

Chronic low back pain diathermy electrophysical agents radiofrequency physiotherapy therapeutic exercise

1. Background

Non-specific chronic low back pain (CLBP) is defined as low back pain (LBP) not attributable to a recognizable, known specific pathology and is the leading cause of disability in both developed and developing countries [1, 2]. The lifetime prevalence of LBP is reported to be as high as 84%, and best estimates suggest that the prevalence of CLBP is about 23%, with 11–12% of the population considered disabled due to this condition, which is more frequent and persistent in older adults [3, 4].

People with chronic pain tend to have central and peripheral nervous system hypersensitivity, with dysfunctional pain modulation that tends to aggravate. In addition, these patients have a high rate of kinesiophobia, which causes physical, emotional, cognitive, and somatic deterioration, negatively impacting their quality of life and producing an increase in disability rates [5, 6]. The chronic nature of this condition presents the greatest challenge as it does not tend to improve with time [7].

Since it is a common, multifactorial disease that is difficult to treat effectively, patients with CLBP commonly use more than one non-pharmacologic treatment, with or without consulting a physician [4]. Clinical practice guidelines recommend therapeutic exercise as a key strategy in the treatment of patients with CLBP [8], as well as the use of conservative treatment strategies that do not cause harm to individuals with chronic musculoskeletal disorders [9]. Exercise therapy alone or in combination with other measures is commonly used in the management of chronic symptoms of LBP ( $>$ 12 weeks), although data from the best available trials indicate only modest benefits [10, 12, 13, 14]. Most of the trials have focused on the strength and endurance of the extensor muscles of the back and abdomen, and on flexibility, and most have included supervised exercise programs once or twice a week, or have included additional unsupervised exercise [15].

Another treatment option available for chronic pain is the application of electrophysical agents such as radiofrequency, which is an electrotherapeutic technique based on the transformation of relatively high frequency energy (0.5–1 MHz) into internal heat within the body [16]. This heat is capable of producing changes in the properties of superficial and deep tissues at the cellular and systemic levels [17, 18, 19, 20]. Radiofrequency diathermy, based on capacitive-dielectric energy transmission, transmits energy regardless of tissue resistance or uptake, in addition to being more comfortable and safer for the patient, since the skin does not reach a high temperature [21]. Regarding the type of application, monopolar devices, which consist of an applicator that works as an antenna [17, 21], are more often recommended than bipolar devices since the latter require a signal transmitter and a plate to close the circuit, and are not recommended in the presence of osteosynthetic materials [22]. Despite monopolar dielectric diathermy by emission of radiofrequency (MDR) being relatively new, it has already achieved worldwide clinical use. Some recently published studies have determined that MDR increases the temperature of deep organs or tissues and the local blood flow, stimulates tissue metabolism, decreases pain and inflammation, reduces muscle spasms, quickens cell activity and increases the elasticity and repair of connective tissues [17, 22, 23, 24].

Some studies highlight the potential benefits of integrating MDR into treatment protocols for musculoskeletal pain. However, most studies on MDR have focused on other musculoskeletal conditions [21, 25, 26, 27, 28], and there is limited research specifically on CLBP. Moreover, existing studies have not fully explored the combined effects of MDR and supervised therapeutic exercise on multiple outcome measures such as disability, pain, kinesiophobia, and emotional distress in individuals with CLBP. For instance, Barassi et al. demonstrated that TECAR therapy effectively reduces lumbar pain by increasing the surface temperature and pain pressure threshold [29]. On the other hand, Albornoz-Cabello et al. found that combining radiofrequency diathermy with an exercise program significantly improved patellofemoral pain compared to exercise alone [30], and Jiménez- Sánchez et al. found that diathermy can be considered an effective modality for treating latent myofascial trigger points and cervical disability [31].

Therefore, the purpose of this study is to address these gaps by comparing the effectiveness of MDR plus supervised therapeutic exercise to supervised therapeutic exercise alone on disability, pain, kinesiophobia, quality of life, sleep, emotional distress, isometric endurance of trunk flexor muscles, and lumbar mobility in flexion in individuals with CLBP.

2. Methods

2.1 Study design

This randomized, single-blind clinical trial was conducted following the CONSORT guidelines and approved by the local human research committee of Almería (UALBIO2021/006), adhering to the Declaration of Helsinki principles. The study was registered at ClinicalTrials.gov with identifier NCT05149690. All participants provided informed consent, ensuring compliance with ethical standards in human research.

2.2 Participants

Sixty patients with chronic LBP who were referred for physiotherapy at a clinical unit of the Health Science School of the University of Almería were recruited for this study. To be eligible, patients had to meet the following inclusion criteria: (1) have experienced CLBP for over three months; (2) be between 30 and 65 years of age; (3) score equal to or greater than 4 points on the Roland Morris Disability Questionnaire (RMDQ); (4) not be currently receiving physiotherapy.

Exclusion criteria included: (1) presence of lumbar stenosis; (2) any clinical signs of radiculopathy; (3) spondylolisthesis; (4) fibromyalgia; (5) treatment with corticosteroid or oral medication within the past two weeks; (6) a history of spinal surgery; (7) contraindication for MDR; (8) any disease of the central or peripheral nervous system; (9) cardiac complications and/or patients who have recently undergone radiotherapy.

2.3 Outcome measures

A total of sixty subjects provided demographic and clinical information, and completed a number of self-report measures, as well as a physical examination by an assessor blinded to the treatment allocation of the patients. Outcome measures were assessed before the first treatment session, immediately after treatment, and at two months post-treatment (Figure 1).

Figure 1.

Design and flow of participants through the trial.

2.3.1 Primary outcomes

A 30% improvement was considered an effective threshold for identifying clinically meaningful improvement (MCID) [32, 33].

The RMDQ is a self-reported questionnaire consisting of 24 items reflecting limitations in different activities of daily living attributed to LBP. The total score ranges from 0 (no disability) to 24 (maximum disability) [34]. The MCID for the RMDQ is a change of 7.2 points.

2.3.2 Secondary outcomes

The second disability questionnaire was the Oswestry Disability Index (ODI). The ODI has 10 items referring to activities of daily living that might be disrupted by LBP. Each item is answered on a 6-point Likert scale ranging from “no problem at all” (0) to “not possible” (5). The total score ranges from 0 to 50 [35]. The MCID for the ODI is a change of 15 points.

A 10-point Visual Analogue Scale (VAS; 0: no pain, 10: maximum pain) was used to assess the patients’ current level of pain, and the worst and lowest levels of pain experienced in the preceding 24 hours [36]. The MCID for the VAS is a change of 3 points.

The Tampa Scale of Kinesiophobia (TSK) is a 17-item questionnaire developed to measure the fear of movement and (re)injury. Each item is scored on a four-point Likert scale ranging from “strongly disagree” (1) to “strongly agree” (4). Ratings are added together to yield a total score (ranging from 17–68 points) [37]. The MCID for the TSK is a change of 15.3 points.

The SF-36 quality of life questionnaire assesses 8 domains including physical functioning, physical role, bodily pain, general health, vitality, social functioning, role-emotional, and mental health. The score ranges from 0 (lowest level of functioning) to 100 (highest level) [38]. The MCID for the SF-36 is a change of 30 points.

The Pittsburgh Sleep Quality Index (PSQI) is a 10-item questionnaire with a total of 19 questions related to sleep habits in the previous month. The questions are divided into 7 areas, each with a score of between 0 and 3 points. The overall score ranges from 0 (no difficulty sleeping) to 21 points (severe difficulty sleeping) [39]. The MCID for the PSQI is a change of 6.3 points.

The Hospital Anxiety and Depression Scale (HADS) assesses emotional distress. It consists of two subscales (HADA: anxiety and HADD: depression) with seven items each that score from 0 (normal) to 3 (abnormal) [40]. The MCID for the HADS is a change of 4.2 points.

To test the isometric endurance of trunk flexor muscles we used the McQuade test [41]. Subjects were supine with their arms crossed over the chest, hands on the opposite shoulders, hips bent, and knees and feet apart. They were asked to continue to lift their head and shoulders until the inferior angle of the scapula lifted from the table [42]. The MCID for this test was a 30% change in the baseline measurement of isometric endurance time.

Lumbar mobility in flexion was determined by measuring the finger-to-floor distance with a tape (cm.) [43, 44]. The MCID for this measure was a 30% change in the baseline measurement of finger-to-floor distance.

2.4 Sample size

The sample size was based on the estimates established by Willan [45]. The calculations were based on the detection of differences of 2.5 points in the RMDQ score [46], assuming a standard deviation of 2.5 points, a 2-tailed test, an alpha ( $α$ ) of 0.05, and a target power (beta) of 85%. The estimated sample size was 60 subjects (30 per group).

2.5 Randomization

A total of 112 patients with CLBP were eligible for this study. Of these, 60 patients who fulfilled all the inclusion criteria and agreed to participate were randomized into two groups: one receiving MDR combined with supervised therapeutic exercise, and the other receiving supervised therapeutic exercise alone. Following the baseline examination, these patients continued with their assigned treatments. Both groups were treated by two physical therapists with more than 10 years of experience in managing patients with CLBP.

Concealed allocation was performed using a compu-ter-generated randomized table of numbers created before the start of data collection by a researcher not involved in the recruitment or treatment of patients. Individual and sequentially numbered index cards with the random assignment were prepared. The index cards were folded and placed in sealed opaque envelopes. Another therapist, blinded to baseline examination, opened the envelope and proceeded with treatment according to the group assignment.

2.6 Interventions

The nature of the intervention did not allow for blinding of the physiotherapist and participants. Patients were required to undergo at least 90% of their scheduled treatment sessions to be considered and remain in the intention-to-treat analysis.

2.6.1 MDR combined supervised therapeutic exercise

Patients in this group received dynamic application of MDR using a new device called the Physicalm^® (Biotronic Advance Develops^®, Granada, Spain), in a prone position. The participants received a pulsating dynamic emission at a frequency of 840 kHz and peak intensity of 30v on the lumbar muscles by means of continuous rotary movements, for a time of 15 minutes. To facilitate the monopolar dielectric transmission, almond oil was used, which is a dielectric substance that minimizes the heating of surface tissues and allows energy to concentrate deep within them (two weekly sessions were performed for four weeks, for a total of eight treatment sessions) [21, 25] (Figure 2).

Figure 2.

Dynamic application of monopolar dielectric diathermy by radiofrequency emission.

Additionally, this group received eight sessions of 30 to 35 minutes of supervised therapeutic exercise. The exercise program consisted mainly of three types of exercises: lumbo-pelvic motor control, strengthening and stretching of the lumbar muscles (two weekly sessions were carried out for four weeks) [47, 48] (Figure 3).

Figure 3.

Supervised therapeutic exercise program group.

2.6.2 Supervised therapeutic exercise

Patients in the therapeutic exercise group received the same program as the diathermy group, two weekly sessions for four weeks. The supervised therapeutic exercise program was performed by two physiotherapists trained in therapeutic exercise for LBP. The patients performed the exercise program in small groups of four and five people, which included the following exercises (mean session duration of 30 to 35 minutes) [48]: diaphragmatic breathing technique, activation of the transverse abdominal muscle, pelvic girdle, glute bridge, spinal column mobility (quadruped cat camel exercise), erector spinae strengthening (prone superman), front plank, side plank, lateral leg-raise for gluteus medium.

2.7 Data analysis

Statistical analysis was performed using SPSS statistical software version 22.0. After a descriptive analysis, the normal distribution of variables was verified by means of the Kolmogorov-Smirnov test. Baseline demographic and clinical variables were compared between both groups using Student’s t-tests for continuous data. Repeated measures analysis of variance (ANOVA 2 $\times$ 3 mixed model) was used to analyze the time effects between both groups and the effects of group interaction for all outcome measurements (RMDQ as primary outcome) between immediately post-treatment and two months later. Changes in variable scores within and between groups were measured by means of a 95% confidence interval of $t$ -tests for paired or independent samples, as appropriate. Effect sizes were calculated using Cohen’s d coefficient, where an effect size between 0.5 and 0.8 is a moderate difference, and $⩾$ 0.8 is a large difference. A $p$ -value $<$ 0.05 was considered statistically significant.

3. Results

3.1 Characteristics of the study participants

Of these, 30 subjects in the intervention group and 30 subjects in the control group were finally included in the analyses (mean age $\pm$ SD: 42.83 $\pm$ 13.65; 55% female) (Table 1). A flow chart of the participants’ recruitment and follow-up is shown in (Figure 1). The groups were similar in terms of all of the variables analyzed before treatment (all $p >$ 0.05; Tables 2–4).

Table 1.
Patient characteristics at baseline.

Outcomes MDR $+$ supervised therapeutic exercise group ( $n =$ 30) Supervised therapeutic exercise group ( $n =$ 30) p-values

Gender (m/f) 11/19 16/14 0.441

Age (years) 41.5 $\pm$ 14.4 44.1 $\pm$ 13.0 0.454

Weight (kg) 71.6 $\pm$ 12.7 77.9 $\pm$ 21.5 0.178

Height (cm) 167.7 $\pm$ 0.1 167.8 $\pm$ 0.1 0.726

Education level (N) 0.113

No studies 2 3 $-$

School level 7 11 $-$

Bachelor level 12 12 $-$

University level 9 4 $-$

Intake of medication 0.343

None 16 13 $-$

Once a week 4 3 $-$

Once every two days 4 6 $-$

Once or twice a day 5 6 $-$

Three or more times a day 1 2 $-$

Outcomes	MDR $+$ supervised therapeutic exercise group ( $n =$ 30)	Supervised therapeutic exercise group ( $n =$ 30)	p-values
Gender (m/f)	11/19	16/14	0.441
Age (years)	41.5 $\pm$ 14.4	44.1 $\pm$ 13.0	0.454
Weight (kg)	71.6 $\pm$ 12.7	77.9 $\pm$ 21.5	0.178
Height (cm)	167.7 $\pm$ 0.1	167.8 $\pm$ 0.1	0.726
Education level (N)			0.113
No studies	2	3	$-$
School level	7	11	$-$
Bachelor level	12	12	$-$
University level	9	4	$-$
Intake of medication			0.343
None	16	13	$-$
Once a week	4	3	$-$
Once every two days	4	6	$-$
Once or twice a day	5	6	$-$
Three or more times a day	1	2	$-$

Values are expressed as absolute and relative frequencies ( $n =$ 60) for categorical variables and as means $\pm$ standard deviations for continuous variables. No differences between groups ( $p >$ 0.050).

3.2 Changes in disability, pain intensity, kinesiophobia, isometric abdominal muscle resistance, and lumbar flexion mobility

The repeated measures ANOVA showed a significant time*groups interaction for the McQuade test (F $=$ 9.50, $p =$ 0.003). For the between-group comparisons, the group that performed MDR with supervised exercise showed significant differences compared to the supervised exercise-only group at all 1 follow-up periods for these outcomes ( $p <$ 0.05), except for the fingers-to-ground test of trunk mobility in flexion at 4 weeks, and the RMDQ at the 12-week follow-up, where the groups were similar. Table 2 shows between group differences.

Table 2.
Baseline, immediate post-treatment, twelve weeks follow-up, and change score between groups for disability, pain, kinesiophobia, isometric resistance of abdominal muscles and lumbar mobility in flexion.

Outcome/group MDR $+$ supervised therapeutic exercise ( $n =$ 30) Supervised therapeutic exercise ( $n =$ 30) Mean differences and CI between groups over time p value Effect size (Cohen’s d)

Self-reported measures

RMDQ (0–24)

Baseline (Week 0) 6.9 $\pm$ 4.6 5.3 $\pm$ 4.8 1.6 ( $-$ 0.8, 4.0)

Post-Treatment (Week 4) 2.2 $\pm$ 2.5 4.0 $\pm$ 4.0 $-$ 1.8 ( $-$ 3.5, $-$ 0.1) 0.040^* Small difference (0.48)

Follow-up (Week 12) 2.1 $\pm$ 2.7 3.8 $\pm$ 3.8 $-$ 1.7 ( $-$ 3.4, 0.0) 0.054 Small difference (0.45)

ODI (0–50)

Baseline (Week 0) 23.2 $\pm$ 16.3 17.1 $\pm$ 15.4 6.2 ( $-$ 2.1, 14.4)

Post-Treatment (Week 4) 7.2 $\pm$ 8.5 13.4 $\pm$ 13.7 $-$ 6.2 ( $-$ 12.1, $-$ 0.3) 0.040^* Small difference (0.48)

Follow-up (Week 12) 6.4 $\pm$ 8.9 13.0 $\pm$ 14.9 $-$ 6.6 ( $-$ 13.0, $-$ 0.3) 0.040^* Small difference (0.48)

VAS (0–10 points)

Baseline (Week 0) 5.4 $\pm$ 2.0 4.4 $\pm$ 2.8 1.1 ( $-$ 0.2, 2.3)

Post-Treatment (Week 4) 1.5 $\pm$ 1.6 2.9 $\pm$ 2.2 $-$ 1.4 ( $-$ 2.4, $-$ 0.4) 0.007^* Moderate difference (0.63)

Follow-up (Week 12) 0.8 $\pm$ 1.2 2.7 $\pm$ 2.0 $-$ 1.8 ( $-$ 2.7, $-$ 1.0) $<$ 0.001^* Large difference (1.02)

TSK (17–68)

Baseline (Week 0) 27.8 $\pm$ 7.2 25.0 $\pm$ 5.7 2.8 ( $-$ 0.5, 6.2)

Post-Treatment (Week 4) 13.8 $\pm$ 4.0 22.5 $\pm$ 6.3 $-$ 8.6 ( $-$ 11.4, $-$ 5.9) $<$ 0.001^* Large difference (1.45)

Follow-up (Week 12) 13.0 $\pm$ 4.6 21.9 $\pm$ 7.1 $-$ 8.9 ( $-$ 12.0, $-$ 5.8) $<$ 0.001^* Large difference (1.31)

Physical outcomes

McQuade Test (s)

Baseline (Week 0) 35.4 $\pm$ 24.7 40.8 $\pm$ 26.0 $-$ 5.4 ( $-$ 18.5, 7.7)

Post-Treatment (Week 4) 63.3 $\pm$ 29.7 47.1 $\pm$ 22.6 16.2 (2.6, 29.9) 0.020^* Small difference (0.48)

Follow-up (Week 12) 74.1 $\pm$ 31.4 48.5 $\pm$ 24.9 25.6 (11.0, 40.2) $<$ 0.001^* Moderate difference (0.71)

Finger-to-floor distance (cm)

Baseline (Week 0) 12.7 $\pm$ 11.1 9.4 $\pm$ 8.0 3.3 ( $-$ 1.7, 8.3)

Post-Treatment (Week 4) 5.0 $\pm$ 6.0 8.4 $\pm$ 7.3 $-$ 3.4 ( $-$ 6.9, 0.1) 0.054 Small difference (0.43)

Follow-up (Week 12) 4.5 $\pm$ 5.8 9.0 $\pm$ 8.2 $-$ 4.5 ( $-$ 8.2, $-$ 0.8) 0.018^* Moderate difference (0.55)

Outcome/group	MDR $+$ supervised therapeutic exercise ( $n =$ 30)	Supervised therapeutic exercise ( $n =$ 30)	Mean differences and CI between groups over time	p value	Effect size (Cohen’s d)
Self-reported measures
RMDQ (0–24)
Baseline (Week 0)	6.9 $\pm$ 4.6	5.3 $\pm$ 4.8	1.6 ( $-$ 0.8, 4.0)
Post-Treatment (Week 4)	2.2 $\pm$ 2.5	4.0 $\pm$ 4.0	$-$ 1.8 ( $-$ 3.5, $-$ 0.1)	0.040^*	Small difference (0.48)
Follow-up (Week 12)	2.1 $\pm$ 2.7	3.8 $\pm$ 3.8	$-$ 1.7 ( $-$ 3.4, 0.0)	0.054	Small difference (0.45)
ODI (0–50)
Baseline (Week 0)	23.2 $\pm$ 16.3	17.1 $\pm$ 15.4	6.2 ( $-$ 2.1, 14.4)
Post-Treatment (Week 4)	7.2 $\pm$ 8.5	13.4 $\pm$ 13.7	$-$ 6.2 ( $-$ 12.1, $-$ 0.3)	0.040^*	Small difference (0.48)
Follow-up (Week 12)	6.4 $\pm$ 8.9	13.0 $\pm$ 14.9	$-$ 6.6 ( $-$ 13.0, $-$ 0.3)	0.040^*	Small difference (0.48)
VAS (0–10 points)
Baseline (Week 0)	5.4 $\pm$ 2.0	4.4 $\pm$ 2.8	1.1 ( $-$ 0.2, 2.3)
Post-Treatment (Week 4)	1.5 $\pm$ 1.6	2.9 $\pm$ 2.2	$-$ 1.4 ( $-$ 2.4, $-$ 0.4)	0.007^*	Moderate difference (0.63)
Follow-up (Week 12)	0.8 $\pm$ 1.2	2.7 $\pm$ 2.0	$-$ 1.8 ( $-$ 2.7, $-$ 1.0)	$<$ 0.001^*	Large difference (1.02)
TSK (17–68)
Baseline (Week 0)	27.8 $\pm$ 7.2	25.0 $\pm$ 5.7	2.8 ( $-$ 0.5, 6.2)
Post-Treatment (Week 4)	13.8 $\pm$ 4.0	22.5 $\pm$ 6.3	$-$ 8.6 ( $-$ 11.4, $-$ 5.9)	$<$ 0.001^*	Large difference (1.45)
Follow-up (Week 12)	13.0 $\pm$ 4.6	21.9 $\pm$ 7.1	$-$ 8.9 ( $-$ 12.0, $-$ 5.8)	$<$ 0.001^*	Large difference (1.31)
Physical outcomes
McQuade Test (s)
Baseline (Week 0)	35.4 $\pm$ 24.7	40.8 $\pm$ 26.0	$-$ 5.4 ( $-$ 18.5, 7.7)
Post-Treatment (Week 4)	63.3 $\pm$ 29.7	47.1 $\pm$ 22.6	16.2 (2.6, 29.9)	0.020^*	Small difference (0.48)
Follow-up (Week 12)	74.1 $\pm$ 31.4	48.5 $\pm$ 24.9	25.6 (11.0, 40.2)	$<$ 0.001^*	Moderate difference (0.71)
Finger-to-floor distance (cm)
Baseline (Week 0)	12.7 $\pm$ 11.1	9.4 $\pm$ 8.0	3.3 ( $-$ 1.7, 8.3)
Post-Treatment (Week 4)	5.0 $\pm$ 6.0	8.4 $\pm$ 7.3	$-$ 3.4 ( $-$ 6.9, 0.1)	0.054	Small difference (0.43)
Follow-up (Week 12)	4.5 $\pm$ 5.8	9.0 $\pm$ 8.2	$-$ 4.5 ( $-$ 8.2, $-$ 0.8)	0.018^*	Moderate difference (0.55)

Values are expressed as mean $\pm$ standard deviation for baseline, immediate post-treatment and at twelve-week follow-up and as mean (95% confidence interval) for between-group change scores. ^*p< 0.05 significant ANOVA adjusted from baseline values for differences between groups. The effect size was represented by Cohen’s d coefficient, where an effect size of $<$ 0.2 reflects an insignificant difference, between 0.2 and 0.5 is considered a small difference, between 0.5 and 0.8 is a moderate difference, and $⩾$ 0.8 is a large difference. ^*Abbreviations: MDR $=$ Monopolar dielectric diathermy radiofrequency; ODI $=$ Oswestry Disability Index; RMDQ $=$ Roland-Morris Low Back and Disability Questionnaire; TSK $=$ Tampa Scale for Kinesiophobia; VAS $=$ Visual Analogue Scale.

For disability, the intervention group showed significant reductions post-treatment (RMDQ: $p =$ 0.040; ODI: $p =$ 0.040). However, at the 12-week follow-up, only the ODI showed significant differences ( $p =$ 0.040). Pain, kinesiophobia and isometric resistance of the trunk muscles improved after treatment (VAS: $p =$ 0.007; TSK: $p <$ 0.001; McQuade test: $p =$ 0.020) and at 12 weeks (VAS: $p =$ 0.001; TSK: $p <$ 0.001; McQuade test: $p =$ 0.001). On the other hand, the lumbar mobility in flexion only improved significantly at 12 weeks ( $p =$ 0.018).

Within-group analysis showed significant pre-post-treatment improvement for all outcomes in both groups [MDR combined with supervised therapeutic exercise group: RMDQ, ODI, VAS, TSK, McQuade test and lumbar mobility in flexion ( $p <$ 0.001); supervised therapeutic exercise group: all outcome ( $p <$ 0.031)]. Showing greater improvements in the MDR combined with supervised therapeutic exercise group; at two months of follow-up, only this group obtained statistically significant differences for VAS ( $t =$ 3.898, $p =$ 0.003, CI $=$ 0.30, 0.96), and the McQuade test ( $t = -$ 4.56, $p <$ 0.001, CI $= -$ 15.64, $-$ 5.95).

3.3 Changes in quality of life, sleep quality, and emotional distress

Regarding quality of life, the 2 $\times$ 3 mixed-model ANOVA with repeated measurements analysis showed significant time * groups interaction for physical role ( $F =$ 6.92, $p =$ 0.011), vitality ( $F =$ 5.46, $p =$ 0.023), social function ( $F =$ 8.30, $p =$ 0.006), and mental health subscales ( $F =$ 4.31, $p =$ 0.042). However, ANOVA did not find a statistically significant result for emotional distress for either the anxiety subscale, depression subscale or for any subscale of the sleep quality questionnaire. Between groups analysis showed significant differences at two months of follow up for the subscales of quality of life on the SF-36: [physical role ( $t =$ 3.582, $p <$ 0.001), vitality ( $t =$ 3.352, $p =$ 0.001), social function ( $t = -$ 2.124, $p =$ 0.038), body pain ( $t =$ 3.343, $p =$ 0.001), and mental health ( $t =$ 3.128, $p =$ 0.003)]; for the habitual sleep efficiency ( $t =$ 2.398, $p =$ 0.020), and total depression state ( $t =$ 2.340, $p =$ 0.023). Tables 3 and 4 shows between-group differences for these outcomes.

Table 3.
Changes baseline, post treatment, and at twelve-week follow-up on quality of life SF-36.

Outcome/group MDR $+$ supervised therapeutic exercise ( $n =$ 30) Supervised therapeutic exercise ( $n =$ 30) Mean differences and CI between groups over time p value Effect size (Cohen’s d)

Quality of life SF-36 Questionnaire

Physical function

Baseline (Week 0) 66.7 $\pm$ 26.6 72.3 $\pm$ 20.5 $-$ 5.7 ( $-$ 17.9, 6.6)

Post-Treatment (Week 4) 81.0 $\pm$ 22.8 81.3 $\pm$ 17.3 $-$ 0.3 ( $-$ 10.8, 10.1) 0.949 Insignificant difference (0.01)

Follow-up (Week 12) 85.8 $\pm$ 20.0 82.0 $\pm$ 16.6 3.8 ( $-$ 5.7, 13.3) 0.422 Insignificant difference (0.16)

Physical Role

Baseline (Week 0) 61.3 $\pm$ 33.7 66.2 $\pm$ 32.3 $-$ 4.9 ( $-$ 21.8, 12.0)

Post-Treatment (Week 4) 88.5 $\pm$ 19.1 72.8 $\pm$ 26.8 15.7 (3.7, 27.7) 0.011^* Moderate difference (0.58)

Follow-up (Week 12) 92.7 $\pm$ 15.5 71.7 $\pm$ 28.1 21.0 (9.3, 32.7) $<$ 0.001^* Large difference (0.83)

Body pain

Baseline (Week 0) 48.4 $\pm$ 22.6 57.8 $\pm$ 24.1 $-$ 9.3 ( $-$ 21.4, 2.7)

Post-Treatment (Week 4) 77.3 $\pm$ 18.0 66.3 $\pm$ 22.1 11.0 (0.6, 21.4) 0.039^* Small difference (0.46)

Follow-up (Week 12) 86.2 $\pm$ 14.9 69.7 $\pm$ 22.6 16.5 (6.6, 26.4) 0.001^* Moderate difference (0.76)

General Health

Baseline (Week 0) 55.7 $\pm$ 24.4 61.5 $\pm$ 16.8 $-$ 5.8 ( $-$ 16.7, 5.0)

Post-Treatment (Week 4) 63.3 $\pm$ 21.6 68.0 $\pm$ 19.2 $-$ 4.7 ( $-$ 15.2, 5.9) 0.379 Insignificant difference (0.18)

Follow-up (Week 12) 63.0 $\pm$ 25.3 70.8 $\pm$ 19.9 $-$ 7.2 ( $-$ 18.9, 4.6) 0.228 Small difference (0.27)

Vitality

Baseline (Week 0) 46.7 $\pm$ 22.3 53.2 $\pm$ 22.6 $-$ 6.5 ( $-$ 18.1, 5.1)

Post-Treatment (Week 4) 75.2 $\pm$ 23.2 63.3 $\pm$ 17.1 11.8 (1.3, 22.4) 0.028^* Small difference (0.45)

Follow-up (Week 12) 80.2 $\pm$ 23.3 62.0 $\pm$ 18.5 18.2 (7.3, 29.0) 0.001^* Moderate difference (0.68)

Social Functioning

Baseline (Week 0) 67.5 $\pm$ 29.3 74.2 $\pm$ 25.0 $-$ 6.7 ( $-$ 20.7, 7.4)

Post-Treatment (Week 4) 82.5 $\pm$ 22.7 83.8 $\pm$ 18.9 $-$ 1.3 ( $-$ 12.0, 9.5) 0.817 Insignificant difference (0.05)

Follow-up (Week 12) 73.3 $\pm$ 30.0 86.7 $\pm$ 16.7 $-$ 13.3 ( $-$ 25.9, $-$ 0.8) 0.038^* Small difference (0.42)

Mental Health

Baseline (Week 0) 60.5 $\pm$ 23.0 62.7 $\pm$ 20.0 $-$ 2.1 ( $-$ 13.3, 9.0)

Post-Treatment (Week 4) 75.2 $\pm$ 19.3 65.9 $\pm$ 19.6 9.3 ( $-$ 0.7, 19.4) 0.068 Small difference (0.39)

Follow-up (Week 12) 81.9 $\pm$ 18.3 65.9 $\pm$ 21.2 16.0 (5.8, 26.2) 0.003^* Moderate difference (0.68)

Emotional Role

Baseline (Week 0) 66.7 $\pm$ 38.9 66.7 $\pm$ 42.9 0.1 ( $-$ 21.1, 21.2)

Post-Treatment (Week 4) 89.4 $\pm$ 22.4 72.2 $\pm$ 36.2 17.2 (1.6, 32.7) 0.031^* Moderate difference (0.51)

Follow-up (Week 12) 84.1 $\pm$ 25.7 72.2 $\pm$ 38.2 11.9 ( $-$ 4.7, 28.7) 0.163 Small difference (0.32)

Outcome/group	MDR $+$ supervised therapeutic exercise ( $n =$ 30)	Supervised therapeutic exercise ( $n =$ 30)	Mean differences and CI between groups over time	p value	Effect size (Cohen’s d)
Quality of life SF-36 Questionnaire
Physical function
Baseline (Week 0)	66.7 $\pm$ 26.6	72.3 $\pm$ 20.5	$-$ 5.7 ( $-$ 17.9, 6.6)
Post-Treatment (Week 4)	81.0 $\pm$ 22.8	81.3 $\pm$ 17.3	$-$ 0.3 ( $-$ 10.8, 10.1)	0.949	Insignificant difference (0.01)
Follow-up (Week 12)	85.8 $\pm$ 20.0	82.0 $\pm$ 16.6	3.8 ( $-$ 5.7, 13.3)	0.422	Insignificant difference (0.16)
Physical Role
Baseline (Week 0)	61.3 $\pm$ 33.7	66.2 $\pm$ 32.3	$-$ 4.9 ( $-$ 21.8, 12.0)
Post-Treatment (Week 4)	88.5 $\pm$ 19.1	72.8 $\pm$ 26.8	15.7 (3.7, 27.7)	0.011^*	Moderate difference (0.58)
Follow-up (Week 12)	92.7 $\pm$ 15.5	71.7 $\pm$ 28.1	21.0 (9.3, 32.7)	$<$ 0.001^*	Large difference (0.83)
Body pain
Baseline (Week 0)	48.4 $\pm$ 22.6	57.8 $\pm$ 24.1	$-$ 9.3 ( $-$ 21.4, 2.7)
Post-Treatment (Week 4)	77.3 $\pm$ 18.0	66.3 $\pm$ 22.1	11.0 (0.6, 21.4)	0.039^*	Small difference (0.46)
Follow-up (Week 12)	86.2 $\pm$ 14.9	69.7 $\pm$ 22.6	16.5 (6.6, 26.4)	0.001^*	Moderate difference (0.76)
General Health
Baseline (Week 0)	55.7 $\pm$ 24.4	61.5 $\pm$ 16.8	$-$ 5.8 ( $-$ 16.7, 5.0)
Post-Treatment (Week 4)	63.3 $\pm$ 21.6	68.0 $\pm$ 19.2	$-$ 4.7 ( $-$ 15.2, 5.9)	0.379	Insignificant difference (0.18)
Follow-up (Week 12)	63.0 $\pm$ 25.3	70.8 $\pm$ 19.9	$-$ 7.2 ( $-$ 18.9, 4.6)	0.228	Small difference (0.27)
Vitality
Baseline (Week 0)	46.7 $\pm$ 22.3	53.2 $\pm$ 22.6	$-$ 6.5 ( $-$ 18.1, 5.1)
Post-Treatment (Week 4)	75.2 $\pm$ 23.2	63.3 $\pm$ 17.1	11.8 (1.3, 22.4)	0.028^*	Small difference (0.45)
Follow-up (Week 12)	80.2 $\pm$ 23.3	62.0 $\pm$ 18.5	18.2 (7.3, 29.0)	0.001^*	Moderate difference (0.68)
Social Functioning
Baseline (Week 0)	67.5 $\pm$ 29.3	74.2 $\pm$ 25.0	$-$ 6.7 ( $-$ 20.7, 7.4)
Post-Treatment (Week 4)	82.5 $\pm$ 22.7	83.8 $\pm$ 18.9	$-$ 1.3 ( $-$ 12.0, 9.5)	0.817	Insignificant difference (0.05)
Follow-up (Week 12)	73.3 $\pm$ 30.0	86.7 $\pm$ 16.7	$-$ 13.3 ( $-$ 25.9, $-$ 0.8)	0.038^*	Small difference (0.42)
Mental Health
Baseline (Week 0)	60.5 $\pm$ 23.0	62.7 $\pm$ 20.0	$-$ 2.1 ( $-$ 13.3, 9.0)
Post-Treatment (Week 4)	75.2 $\pm$ 19.3	65.9 $\pm$ 19.6	9.3 ( $-$ 0.7, 19.4)	0.068	Small difference (0.39)
Follow-up (Week 12)	81.9 $\pm$ 18.3	65.9 $\pm$ 21.2	16.0 (5.8, 26.2)	0.003^*	Moderate difference (0.68)
Emotional Role
Baseline (Week 0)	66.7 $\pm$ 38.9	66.7 $\pm$ 42.9	0.1 ( $-$ 21.1, 21.2)
Post-Treatment (Week 4)	89.4 $\pm$ 22.4	72.2 $\pm$ 36.2	17.2 (1.6, 32.7)	0.031^*	Moderate difference (0.51)
Follow-up (Week 12)	84.1 $\pm$ 25.7	72.2 $\pm$ 38.2	11.9 ( $-$ 4.7, 28.7)	0.163	Small difference (0.32)

Values are expressed as mean $\pm$ standard deviation for immediate post-treatment, and at twelve-week follow-up, and as mean (95% confidence interval) for between-group change scores. ^*p< 0.05 significant ANOVA adjusted from baseline values for differences among groups. The effect size was represented by Cohen’s d coefficient, where an effect size of $<$ 0.2 reflects an insignificant difference, between 0.2 and 0.5 is considered a small difference, between 0.5 and 0.8 is a moderate difference, and $⩾$ 0.8 is a large difference.

Table 4.

Changes baseline, post treatment, and at twelve-week follow-up on quality of sleep, emotional distress HADS anxiety and depression subscales.

Outcome/group	MDR $+$ supervised therapeutic exercise ( $n =$ 30)	Supervised therapeutic exercise ( $n =$ 30)	Mean differences and CI between groups over time	p value	Effect size (Cohen’s d)
Pittsburgh Sleep Quality Index (0–21)
Total score
Baseline (Week 0)	8.6 $\pm$ 4.6	7.7 $\pm$ 4.8	0.9 ( $-$ 1.5, 3.4)
Post-Treatment (Week 4)	7.6 $\pm$ 4.6	6.6 $\pm$ 4.3	1.0 ( $-$ 1.3, 3.3)	0.389	Insignificant difference (0.18)
Follow-up (Week 12)	8.8 $\pm$ 5.3	6.9 $\pm$ 4.5	2.0 ( $-$ 0.6, 4.5)	0.125	Small difference (0.31)
Daily sleep disfunction
Baseline (Week 0)	1.1 $\pm$ 1.2	1.0 $\pm$ 1.0	0.1 ( $-$ 0.4, 0.7)
Post-Treatment (Week 4)	1.2 $\pm$ 1.3	0.9 $\pm$ 0.9	0.3 ( $-$ 0.3, 0.9)	0.307	Small difference (0.21)
Follow-up (Week 12)	1.3 $\pm$ 1.3	0.8 $\pm$ 0.9	0.5 ( $-$ 0.1, 1.1)	0.072	Small difference (0.35)
Use of Hypnotics for Sleep
Baseline (Week 0)	0.7 $\pm$ 1.2	0.4 $\pm$ 0.9	0.3 ( $-$ 0.2, 0.9)
Post-Treatment (Week 4)	0.7 $\pm$ 1.1	0.4 $\pm$ 0.9	0.3 ( $-$ 0.2, 0.8)	0.249	Small difference (0.24)
Follow-up (Week 12)	0.8 $\pm$ 1.2	0.5 $\pm$ 0.9	0.3 ( $-$ 0.2, 0.9)	0.246	Small difference (0.22)
Sleep Pertubation
Baseline (Week 0)	1.6 $\pm$ 0.7	1.5 $\pm$ 0.7	1.3 ( $-$ 0.2, 0.5)
Post-Treatment (Week 4)	1.3 $\pm$ 0.6	1.3 $\pm$ 0.5	$-$ 0.0 ( $-$ 0.3, 0.3)	0.818	Insignificant difference (0.00)
Follow-up (Week 12)	1.4 $\pm$ 0.8	1.2 $\pm$ 0.5	0.2 ( $-$ 0.1, 0.6)	0.177	Small difference 0.23
Habitual Sleep Efficacy
Baseline (Week 0)	1.1 $\pm$ 1.2	0.7 $\pm$ 1.1	0.4 ( $-$ 0.2, 1.0)
Post-Treatment (Week 4)	1.2 $\pm$ 1.2	0.7 $\pm$ 0.9	0.4 ( $-$ 0.1, 1.0)	0.121	Small difference (0.37)
Follow-up (Week 12)	1.4 $\pm$ 1.2	0.7 $\pm$ 1.0	0.7 (0.1, 1.2)	0.020^*	Moderate difference (0.50)
Sleep duration
Baseline (Week 0)	1.4 $\pm$ 1.0	1.3 $\pm$ 1.0	0.1 ( $-$ 0.5, 0.6)
Post-Treatment (Week 4)	1.5 $\pm$ 1.0	1.3 $\pm$ 0.9	0.2 ( $-$ 0.3, 0.7)	0.341	Insignificant difference (0.17)
Follow-up (Week 12)	1.5 $\pm$ 0.9	1.3 $\pm$ 0.9	0.3 ( $-$ 0.2, 0.7)	0.267	Insignificant difference (0.18)
Sleep latency
Baseline (Week 0)	1.8 $\pm$ 1.0	1.5 $\pm$ 1.1	0.3 ( $-$ 0.3, 0.8)
Post-Treatment (Week 4)	1.4 $\pm$ 1.0	1.2 $\pm$ 1.1	0.2 ( $-$ 0.3, 0.8)	0.383	Insignificant difference (0.16)
Follow-up (Week 12)	1.6 $\pm$ 1.1	1.3 $\pm$ 1.2	0.3 ( $-$ 0.3, 0.8)	0.357	Small difference (0.22)
Subjective sleep quality
Baseline (Week 0)	1.4 $\pm$ 0.8	1.3 $\pm$ 0.8	0.1 ( $-$ 0.3, 0.5)
Post-Treatment (Week 4)	1.1 $\pm$ 0.8	1.0 $\pm$ 0.8	0.2 ( $-$ 0.2, 0.6)	0.406	Insignificant difference (0.10)
Follow-up (Week 12)	1.3 $\pm$ 0.8	1.2 $\pm$ 0.8	0.2 ( $-$ 0.3, 0.6)	0.421	Insignificant difference (0.10)
Hospital anxiety and depression scale (HADS)
HADS-A Anxiety Subscale
Baseline (Week 0)	7.5 $\pm$ 4.8	5.5 $\pm$ 3.8	2.1 ( $-$ 0.2, 4.3)
Post-Treatment (Week 4)	6.4 $\pm$ 4.6	4.2 $\pm$ 3.6	2.1 (0.0, 4.3)	0.048^*	Small difference (0.42)
Follow-up (Week 12)	6.3 $\pm$ 4.5	4.6 $\pm$ 4.0	1.7 ( $-$ 0.5, 3.9)	0.128	Small difference (0.32)
HADS-D Depression Subscale
Baseline (Week 0)	6.3 $\pm$ 4.0	4.6 $\pm$ 3.3	1.7 ( $-$ 0.2, 3.6)
Post-Treatment (Week 4)	5.2 $\pm$ 3.8	3.7 $\pm$ 3.4	1.5 ( $-$ 0.4, 3.4)	0.111	Small difference (0.33)
Follow-up (Week 12)	5.6 $\pm$ 3.5	3.6 $\pm$ 3.4	2.1 (0.3, 3.8)	0.023^*	Small difference (0.47)

For the quality of life, measured by the SF-36 questionnaire, the MDR with supervised therapeutic exercise group showed significant improvements post treatment and at the 12-week follow-up in physical role (post-treatment: $p =$ 0.011; follow-up: $p <$ 0.001), body pain (post-treatment: $p =$ 0.028; follow-up: $p =$ 0.001) and vitality (post-treatment: $p =$ 0.011; follow-up: $p =$ 0.001). Mental health and social functioning only showed significant improvement at follow-up ( $p <$ 0.05).

Regarding within-group comparisons, both groups showed significant differences between baseline and post-treatment for all subscales of the SF-36 quality of life questionnaire (except for mental health), the PSQI (subjective quality, sleep latency, sleep perturbation and total score), and the total anxiety scale. However, at two months follow up, only the patients in the MDR combined with supervised therapeutic exercise group obtained significant differences on the SF-36 [physical function, physical role, vitality, social function, body pain and mental health ( $p <$ 0.05)].

Regarding sleep quality and emotional distress, the intervention group showed the following significant results: habitual sleep efficiency improved significantly at the 12-week follow-up ( $p =$ 0.020). The HADS-A anxiety subscale showed a significant improvement after treatment ( $p =$ 0.048), but this was not maintained at follow-up. While the HADS-D depression subscale showed a significant improvement at the 12-week follow-up ( $p =$ 0.023).

4. Discussion

The clinical trial found that adding MDR using a pulsed dynamic emission of 840 KHz and 30v on the lumbar muscles through continuous rotary movements for 15 minutes, to a supervised therapeutic exercise protocol, resulted in a significantly reduction in pain intensity, disability, kinesiophobia, isometric abdominal muscle resistance, and the following SF-36 domains: physical role, vitality, social function, and mental health.

To determine if the changes were clinically significant, we evaluated the improvements from baseline to 4 weeks post-treatment and at the 12-week follow-up. In terms of disability measured by the RMDQ, the group that received MDR along with supervised therapeutic exercise showed improvements of 68.12% post-treatment and 69.57% at follow-up. For the ODI, this group showed improvements of 68.97% post-treatment and 72.41% at follow-up. Regarding kinesiophobia measured by the TSK, the improvements were 50.36% post-treatment and 53.24% at follow-up. In the McQuade test, which evaluates isometric abdominal muscle resistance, the improvements were 78.81% post-treatment and 109.32% at follow-up. For the finger-to-floor distance, which assesses lumbar flexion mobility, the improvements were 60.63% post-treatment and 64.57% at follow-up. The group that only performed supervised exercise did not achieve clinically significant improvements in any of these domains.

Regarding pain measured by the VAS, the improvements were 72.22% post-treatment and 85.19% at follow-up for the MDR along with supervised therapeutic exercise group. The group that only performed supervised exercise also showed clinically significant improvements in the VAS, with 34.09% post-treatment and 38.64% at follow-up.

The analysis of the SF-36 showed clinically relevant improvements in the MDR along with supervised therapeutic exercise group in the domains of physical role (44.44% post-treatment, 51.22% follow-up), body pain (59.75% post-treatment, 78.10% follow-up), vitality (61.03% post-treatment, 71.73% follow-up), mental health (35.37% follow-up), and emotional role (34% post-treatment). The group that only performed supervised exercise did not achieve clinically significant improvements in any domain.

There is consensus that lumbo-pelvic motor control exercises, alongside strengthening and stretching of the lumbar muscles, represent a foundational treatment for CLBP, as endorsed by clinical practice guidelines [49, 50]. Despite their widespread recommendation, the efficacy of these exercises relative to other forms of conservative treatment remains contentious. To date, numerous systematic reviews and meta-analyses have assessed various stabilization/core/control motor exercises, yielding conclusions that are not definitive and generally do not support a superior effect of these exercises in patients with CLBP [51, 52]. This highlights a gap between guideline recommendations and empirical evidence that warrants further investigation. Recently, a network meta-analysis found that all exercise types, except stretching exercises, when adjusted for additional dose and co-interventions, were consistently more effective than minimal care and most other comparator treatments in reducing pain intensity and improving functional limitations in patients with CLBP [53]. Previous studies have shown that patients with low back pain may have impaired control of the deep muscles of the trunk (e.g., multifidus) responsible for maintaining coordination and spinal stability [54, 55]. Based on this principle, the results obtained in the group of therapeutic exercises based on efficacy and motor control are logical, however, the results of the group that also received diathermy were more significant and lasted longer [56].

Concerning the clinical importance of these results, although both groups had significant reductions in VAS, disability, kinesiophobia, and endurance of trunk flexor muscles, MDR therapy combined with supervised therapeutic exercise was found to be the most effective treatment in reducing pain when comparing post-treatment and two months later, compared to the group that received only supervised therapeutic exercise. In the last two decades, both radiofrequency and ultrasound have been popular choices for many clinicians in treating musculoskeletal disorders, both of which use physical agents that convert high-frequency electric current into deep heat, which promotes healing [17, 22, 57]. This mode of therapy is relatively new, and the effects of MDR therapy on the mechanism of action in CLBP are currently not clarified with certainty. This is the only randomized controlled study known to evaluate the effects of MDR in patients with CLBP. However, Notarnicola et al. conducted a case-control study in patients with CLBP that documented disc disease or disc herniation [28], finding that Tecar therapy, a type of radiofrequency, constituting a monopolar capacitive resistive radiofrequency of 448 kHz was just as effective in reducing pain and disability, both immediately after treatment and two months later, however, this study applied different parameters than the current study. Recently, different studies have evaluated its efficacy on other musculoskeletal conditions such as supraspinatus tendinopathy [58], fibromyalgia syndrome [21], chronic pelvic pain syndrome [26], and knee osteoarthritis [59, 60], or patellofemoral syndrome [25, 59], all of them obtaining a significant decrease in pain and an increase in joint function among the patients. According to general scientific opinion, the efficacy of diathermy lies in generating thermophysiological responses in the body, such as changes in the metabolism of the tissue, blood flow, muscle tone, and tissue compliance, thereby affecting underlying pathological processes. Ultimately, induced tissue hyperthermia can lead to effects such as reduced pain and inflammation, accelerated tissue healing, and general improvements in function [17, 22, 54, 57]. Observing significant differences between the two groups is to be expected if the previously-demonstrated effects of therapeutic exercise are added to the effects of MDR. In addition, consistent with these findings, a recent study by Albornoz-Cabello et al., concluded that the addition of MDR treatment to home knee therapeutic exercises obtained better results for pain, functionality and range of movement in flexion than home exercises alone [61]. Regarding quality of life, previous studies do not show any significant improvement when using MDR in patients with fibromyalgia [21], even though these patients exhibit much higher psychiatric distress, depression and behavioral sequelae than other patients with chronic pain, which would explain the ineffectiveness of treatments without a psychosocial component [62, 63]. Based on the evidence available on chronic pain, we suppose that the pain relief of MDR produced an improvement in kinesiophobia and the return to movement improved quality of life with CLBP.

The results of the PSQI, regarding sleep quality, and the HADS, regarding emotional distress, did not show clinically significant changes, as none of the subscales reached the 30% improvement threshold. This highlights the need for additional approaches to improve sleep quality and emotional distress in patients with chronic low back pain.

The limitations include that the study was performed for a short period of time, thus it was not capable of entirely evaluating the long-term effects of each intervention. Therefore, future trials should be designed for a longer period of time to completely assess the effects. Secondly, a double-blind design would have been desirable over a single-blind design in order to avoid the risk of bias. Thirdly, the absence of a placebo group is another limitation, which should be considered for further studies.

5. Conclusions

The present study provides evidence that the combination of MDR and supervised therapeutic exercise is an effective treatment for individuals with CLBP, resulting in statistically significant improvements in pain intensity, disability, kinesiophobia, trunk flexor muscle endurance, and specific domains of the SF-36. These improvements were more significant and long-lasting than those achieved with supervised therapeutic exercise alone.

Footnotes

Acknowledgments

The authors sincerely thank all participants for their invaluable contribution to this study.

Ethics statement

The protocol was approved by the local human research committee of Almeria University (UALBIO2021/006). The study was conducted following the ethical standards laid out in the latest revision of the Declaration of Helsinki, as adopted by the World Medical Association, ensuring all research was performed with the highest standards of human rights and scientific integrity. Written informed consent was obtained from all individual participants included in the study.

Consent for publication

Written informed consent for publication of their therapeutic images was obtained from the patients.

Competing interests

The authors declare that they have no competing interests.

Author contributions

ICLP, AMCS, and HGL were the brains behind the original concept, idea, and research design. Writing of the manuscript was primarily done by ICLP, HGL, and MAQZ. Data collection was handled by AMCA and MFS. Data analysis was conducted by ICLP and AMCS. Tables 1–4 were prepared by ICLP, HGL, and MFS. Figures 1– were developed by AMCA and AMCS. Participants were provided by MAQZ and AMCA. All authors were involved in the study design and protocol development. All authors read and approved the final manuscript before submission.

Funding

None to report.

Availability of data and materials

The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.

References

Maher

Underwood

Buchbinder

. Non-specific low back pain. Lancet. 2017; 389(10070): 736-747. doi: 10.1016/S0140-6736(16)30970-9.

Balagué

Mannion

Pellisé

Cedraschi

. Non-specific low back pain. Lancet. 2012; 379(9814): 482-491. doi: 10.1016/S0140-6736(11)60610-7.

Adamson

Hunt

Nazareth

. The influence of socio-demographic characteristics on consultation for back pain – a review of the literature. Fam Pract. 2011; 28(2): 163-171. doi: 10.1093/fampra/cmq085.

Airaksinen

Brox

Cedraschi

Hildebrandt

Klaber-Moffett

Kovacs

Mannion

Reis

Staal

Ursin

Zanoli

. COST B13 Working Group on Guidelines for Chronic Low Back Pain. Chapter 4. European guidelines for the management of chronic nonspecific low back pain. Eur Spine J. 2006; 15(2): S192-300. doi: 10.1007/s00586-006-1072-1.

GBD 2015 Disease and Injury Incidence and Prevalence Collaborators. Global, regional, and national incidence, prevalence, and years lived with disability for 310 diseases and injuries, 1990–2015: a systematic analysis for the Global Burden of Disease Study 2015. Lancet. 2016; 388(10053): 1545-1602. doi: 10.1016/S0140-6736(16)31678-6.

Luque-Suarez

Martinez-Calderon

Falla

. Role of kinesiophobia on pain, disability and quality of life in people suffering from chronic musculoskeletal pain: a systematic review. Br J Sports Med. 2019; 53(9): 554-559. doi: 10.1136/bjsports-2017-098673.

Haldeman

Dagenais

. A supermarket approach to the evidence-informed management of chronic low back pain. Spine J. 2008; 8(1): 1-7. doi: 10.1016/j.spinee.2007.10.009.

Qaseem

Wilt

McLean

Forciea

, Clinical Guidelines Committee of the American College of Physicians, Denberg

Barry

Boyd

Chow

Fitterman

Harris

Humphrey

Vijan

. Noninvasive Treatments for Acute, Subacute, and Chronic Low Back Pain: A Clinical Practice Guideline From the American College of Physicians. Ann Intern Med. 2017; 166(7): 514-530. doi: 10.7326/M16-2367.

Martinez-Calderon

Flores-Cortes

Morales-Asencio

Luque-Suarez

. Conservative Interventions Reduce Fear in Individuals With Chronic Low Back Pain: A Systematic Review. Arch Phys Med Rehabil. 2020; 101(2): 329-358. doi: 10.1016/j.apmr.2019.08.470..

10.

Aasa

Berglund

Michaelson

Aasa

. Individualized low-load motor control exercises and education versus a high-load lifting exercise and education to improve activity, pain intensity, and physical performance in patients with low back pain: a randomized controlled trial. J Orthop Sports Phys Ther. 2015; 45(2): 77-85, B1-4. doi: 10.2519/jospt.2015.5021.

11.

Halliday

Pappas

Hancock

Clare

Pinto

Robertson

Ferreira

. A Randomized Controlled Trial Comparing the McKenzie Method to Motor Control Exercises in People With Chronic Low Back Pain and a Directional Preference. J Orthop Sports Phys Ther. 2016; 46(7): 514-522. doi: 10.2519/jospt.2016.6379.

12.

Hayden

van Tulder

Malmivaara

Koes

. Exercise therapy for treatment of non-specific low back pain. Cochrane Database Syst Rev. 2005; 2005(3): CD000335. doi: 10.1002/14651858.CD000335.pub2.

13.

Michaelson

Holmberg

Aasa

. High load lifting exercise and low load motor control exercises as interventions for patients with mechanical low back pain: A randomized controlled trial with 24-month follow-up. J Rehabil Med. 2016; 48(5): 456-463. doi: 10.2340/16501977-2091.

14.

van Tulder

Malmivaara

Hayden

Koes

. Statistical significance versus clinical importance: trials on exercise therapy for chronic low back pain as example. Spine (Phila Pa 1976). 2007; 32(16): 1785-1790. doi: 10.1097/BRS.0b013e3180b9ef49.

15.

Searle

Spink

Chuter

. Exercise interventions for the treatment of chronic low back pain: a systematic review and meta-analysis of randomised controlled trials. Clin Rehabil. 2015; 29(12): 1155-1167. doi: 10.1177/0269215515570379.

16.

Martin

Mccallum

Strelley

Heaton

. Electromagnetic Fields from Therapeutic Diathermy Equipment: A review of hazards and precautions. Physiotherapy. 1991; 77: 3-7.

17.

Kumaran

Watson

. Radiofrequency-based treatment in therapy-related clinical practice – a narrative review. Part II: chronic conditions. Physical Therapy Reviews. 2015; 20: 325-43.

18.

deLateur

Hinderer

. Physiatric therapeutics. 2. Therapeutic heat and cold, electrotherapy, and therapeutic exercise. Arch Phys Med Rehabil. 1990; 71(4-S): S260-3.

19.

Hall

. Guyton and Hall textbook of medical physiology. 13th edition. Philadelphia, PA: Elsevier; 2016.

20.

Watson

, editor. Electrotherapy: evidence-based practice. 12th ed. Edinburgh; New York: Churchill Livingstone; 2008.

21.

Ibáñez-Vera

García-Romero

Alvero-Cruz

Lomas-Vega

. Effects of Monopolar Dielectric Radiofrequency Signals on the Symptoms of Fibromyalgia: A Single-Blind Randomized Controlled Trial. Int J Environ Res Public Health. 2020; 17(7): 2465. doi: 10.3390/ijerph17072465.

22.

Kumaran

Watson

. Thermal build-up, decay and retention responses to local therapeutic application of 448 kHz capacitive resistive monopolar radiofrequency: A prospective randomised crossover study in healthy adults. Int J Hyperthermia. 2015; 31(8): 883-895. doi: 10.3109/02656736.2015.1092172.

23.

Tashiro

Hasegawa

Yokota

Nishiguchi

Fukutani

Shirooka

Tasaka

Matsushita

Matsubara

Nakayama

Sonoda

Tsuboyama

Aoyama

. Effect of Capacitive and Resistive electric transfer on haemoglobin saturation and tissue temperature. Int J Hyperthermia. 2017; 33(6): 696-702. doi: 10.1080/02656736.2017.1289252.

24.

Wust

Kortüm

Strauss

Nadobny

Zschaeck

Beck

Stein

Ghadjar

. Non-thermal effects of radiofrequency electromagnetic fields. Sci Rep. 2020; 10(1): 13488. doi: 10.1038/s41598-020-69561-3.

25.

Albornoz-Cabello

Barrios-Quinta

Escobio-Prieto

Sobrino-Sánchez

Ibáñez-Vera

Espejo-Antúnez

. Treatment of Patellofemoral Pain Syndrome with Dielectric Radiofrequency Diathermy: A Preliminary Single-Group Study with Six-Month Follow-Up. Medicina (Kaunas). 2021; 57(5): 429. doi: 10.3390/medicina57050429.

26.

Carralero-Martínez

Muñoz Pérez

Kauffmann

Blanco-Ratto

Ramírez-García

. Efficacy of capacitive resistive monopolar radiofrequency in the physiotherapeutic treatment of chronic pelvic pain syndrome: A randomized controlled trial. Neurourol Urodyn. 2022; 41(4): 962-972. doi: 10.1002/nau.24903.

27.

Weber

Kabelka

. Noninvasive monopolar capacitive-coupled radiofrequency for the treatment of pain associated with lateral elbow tendinopathies: 1-year follow-up. PM R. 2012; 4(3): 176-181. doi: 10.1016/j.pmrj.2011.11.003.

28.

Notarnicola

Maccagnano

Gallone

Covelli

Tafuri

Moretti

. Short term efficacy of capacitive-resistive diathermy therapy in patients with low back pain: a prospective randomized controlled trial. J Biol Regul Homeost Agents. 2017; 31(2): 509-515.

29.

Barassi

Mariani

Supplizi

Prosperi

Di Simone

Marinucci

Pellegrino

Guglielmi

Younes

Di Iorio

. Capacitive and Resistive Electric Transfer Therapy: A Comparison of Operating Methods in Non-specific Chronic Low Back Pain. Adv Exp Med Biol. 2022; 1375: 39-46. doi: 10.1007/5584_2021_692.

30.

Albornoz-Cabello

Ibáñez-Vera

Barrios-Quinta

Espejo-Antúnez

Lara-Palomo

de Los Ángeles Cardero-Durán

. Non-Invasive Radiofrequency Diathermy Neuromodulation Added to supervised therapeutic exercise in Patellofemoral Pain Syndrome: A Single Blind Randomized Controlled Trial with Six Months of Follow-Up. Biomedicines. 2024; 12(4): 850. doi: 10.3390/biomedicines12040850.

31.

Jiménez-Sánchez

Cordova-Alegre

Carpallo-Porcar

Burgos-Bragado

Sanjuan-Sánchez

Brandín-de la Cruz

. Effects of transcutaneous radiofrequency diathermy versus ultrasound on latent myofascial trigger points in the upper trapezius: A randomized crossover trial. J Back Musculoskelet Rehabil. 2024. doi: 10.3233/BMR-230296.

32.

Ostelo

de Vet

. Clinically important outcomes in low back pain. Best Pract Res Clin Rheumatol. 2005; 19(4): 593-607. doi: 10.1016/j.berh.2005.03.003.

33.

Ostelo

Deyo

Stratford

Waddell

Croft

Von Korff

Bouter

de Vet

. Interpreting change scores for pain and functional status in low back pain: towards international consensus regarding minimal important change. Spine (Phila Pa 1976). 2008; 33(1): 90-4. doi: 10.1097/BRS.0b013e31815e3a10.

34.

Kovacs

Llobera

Gil Del Real

Abraira

Gestoso

Fernández

Primaria Group

. Validation of the spanish version of the Roland-Morris questionnaire. Spine (Phila Pa 1976). 2002; 27(5): 538-542. doi: 10.1097/00007632-200203010-00016.

35.

Roland

Fairbank

. The Roland-Morris Disability Questionnaire and the Oswestry Disability Questionnaire. Spine (Phila Pa 1976). 2000; 25(24): 3115-3124. doi: 10.1097/00007632-200012150-00006.

36.

Johnson

. Visual analog scale (VAS). Am J Phys Med Rehabil. 2001; 80(10): 717. doi: 10.1097/00002060-200110000-00001.

37.

Gómez-Pérez

López-Martínez

Ruiz-Párraga

. Psychometric Properties of the Spanish Version of the Tampa Scale for Kinesiophobia (TSK). J Pain. 2011; 12(4): 425-435. doi: 10.1016/j.jpain.2010.08.004.

38.

Brazier

Harper

Jones

O’Cathain

Thomas

Usherwood

Westlake

. Validating the SF-36 health survey questionnaire: new outcome measure for primary care. BMJ. 1992; 305(6846): 160-164. doi: 10.1136/bmj.305.6846.160.

39.

Buysse

Reynolds

3rd, Monk

Berman

Kupfer

. The Pittsburgh Sleep Quality Index: a new instrument for psychiatric practice and research. Psychiatry Res. 1989; 28(2): 193-213. doi: 10.1016/0165-1781(89)90047-4.

40.

Quintana

Padierna

Esteban

Arostegui

Bilbao

Ruiz

. Evaluation of the psychometric characteristics of the Spanish version of the Hospital Anxiety and Depression Scale. Acta Psychiatr Scand. 2003; 107(3): 216-221. doi: 10.1034/j.1600-0447.2003.00062.x.

41.

McQuade

Turner

Buchner

. Physical fitness and chronic low back pain. An analysis of the relationships among fitness, functional limitations, and depression. Clin Orthop Relat Res. 1988; (233): 198-204.

42.

McGill

Childs

Liebenson

. Endurance times for low back stabilization exercises: clinical targets for testing and training from a normal database. Arch Phys Med Rehabil. 1999; 80(8): 941-944. doi: 10.1016/s0003-9993(99)90087-4.

43.

Frost

Stuckey

Smalley

Dorman

. Reliability of measuring trunk motions in centimeters. Phys Ther. 1982; 62(10): 1431-1437. doi: 10.1093/ptj/62.10.1431.

44.

Tousignant

Poulin

Marchand

Viau

Place

. The Modified-Modified Schober Test for range of motion assessment of lumbar flexion in patients with low back pain: a study of criterion validity, intra- and inter-rater reliability and minimum metrically detectable change. Disabil Rehabil. 2005; 27(10): 553-559. doi: 10.1080/09638280400018411.

45.

Willan

. Analysis, sample size, and power for estimating incremental net health benefit from clinical trial data. Control Clin Trials. 2001; 22(3): 228-237. doi: 10.1016/s0197-2456(01)00110-6.

46.

Jordan

Dunn

Lewis

Croft

. A minimal clinically important difference was derived for the Roland-Morris Disability Questionnaire for low back pain. J Clin Epidemiol. 2006; 59(1): 45-52. doi: 10.1016/j.jclinepi.2005.03.018.

47.

Matarán-Peñarrocha

Lara Palomo

Antequera Soler

Gil-Martínez

Fernández-Sánchez

Aguilar-Ferrándiz

Castro-Sánchez

. Comparison of efficacy of a supervised versus non-supervised physical therapy exercise program on the pain, functionality and quality of life of patients with non-specific chronic low-back pain: a randomized controlled trial. Clin Rehabil. 2020; 34(7): 948-959. doi: 10.1177/0269215520927076.

48.

Ibrahim

Akindele

Ganiyu

. Motor control exercise and patient education program for low resource rural community dwelling adults with chronic low back pain: a pilot randomized clinical trial. J Exerc Rehabil.2018; 14(5): 851-863. doi: 10.12965/jer.1836348.174.

49.

Chou

Qaseem

Snow

Casey

Cross

Jr., Shekelle

Owens

. Clinical Efficacy Assessment Subcommittee of the American College of Physicians; American College of Physicians; American Pain Society Low Back Pain Guidelines Panel. Diagnosis and treatment of low back pain: a joint clinical practice guideline from the American College of Physicians and the American Pain Society. Ann Intern Med. 2007; 147(7): 478-491. doi: 10.7326/0003-4819-147-7-200710020-00006.

50.

Oliveira

Maher

Pinto

Traeger

Lin

Chenot

van Tulder

Koes

. Clinical practice guidelines for the management of non-specific low back pain in primary care: an updated overview. Eur Spine J. 2018; 27(11): 2791-2803. doi: 10.1007/s00586-018-5673-2.

51.

Hayden

Ellis

Ogilvie

Malmivaara

van Tulder

. Exercise therapy for chronic low back pain. Cochrane Database Syst Rev. 2021; 9(9): CD009790. doi: 10.1002/14651858.

52.

Saragiotto

Maher

Yamato

Costa

Menezes Costa

Ostelo

Macedo

. Motor control exercise for chronic non-specific low-back pain. Cochrane Database Syst Rev. 2016; 2016(1): CD012004. doi: 10.1002/14651858.CD012004.

53.

Zhang

Zhong

Feng

Zhang

Wang

. Effectiveness of motor control exercise on non-specific chronic low back pain, disability and core muscle morphological characteristics: a meta-analysis of randomized controlled trials. Eur J Phys Rehabil Med2021; 57(5): 793-806. doi: 10.23736/S1973-9087.21.06555-2.

54.

Hodges

Richardson

. Inefficient muscular stabilization of the lumbar spine associated with low back pain. A motor control evaluation of transversus abdominis. Spine (Phila Pa 1976). 1996; 21(22): 2640-50. doi: 10.1097/00007632-199611150-00014.

55.

Hodges

Richardson

. Delayed postural contraction of transversus abdominis in low back pain associated with movement of the lower limb. J Spinal Disord. 1998; 11(1): 46-56.

56.

Macedo

Maher

Latimer

McAuley

. Motor control exercise for persistent, nonspecific low back pain: a systematic review. Phys Ther. 2009; 89(1): 9-25. doi: 10.2522/ptj.20080103.

57.

Kumaran

Herbland

Watson

. Continuous-mode 448 kHz capacitive resistive monopolar radiofrequency induces greater deep blood flow changes compared to pulsed mode shortwave: a crossover study in healthy adults. Eur J of Physiother. 2017; 19: 137-146.

58.

Giombini

Di Cesare

Safran

Ciatti

Maffulli

. Short-term effectiveness of hyperthermia for supraspinatus tendinopathy in athletes: a short-term randomized controlled study. Am J Sports Med. 2006; 34(8): 1247-1253. doi: 10.1177/0363546506287827.

59.

Kumaran

Watson

. Treatment using 448kHz capacitive resistive monopolar radiofrequency improves pain and function in patients with osteoarthritis of the knee joint: a randomised controlled trial. Physiotherapy. 2019; 105(1): 98-107. doi: 10.1016/j.physio.2018.07.004.

60.

García-Marín

Rodríguez-Almagro

Castellote-Caballero

Achalandabaso-Ochoa

Lomas-Vega

Ibáñez-Vera

. Efficacy of Non-Invasive Radiofrequency-Based Diathermy in the Postoperative Phase of Knee Arthroplasty: A Double-Blind Randomized Clinical Trial. J Clin Med. 2021; 10(8): 1611. doi: 10.3390/jcm10081611.

61.

Albornoz-Cabello

Ibáñez-Vera

Aguilar-Ferrándiz

Espejo-Antúnez

. Monopolar dielectric diathermy by emission of radiofrequency in Patellofemoral pain. A single-blind-randomized clinical trial. Electromagn Biol Med. 2020; 39(4): 282-289. doi: 10.1080/15368378.2020.1793169.

62.

Hassett

Cone

Patella

Sigal

. The role of catastrophizing in the pain and depression of women with fibro-myalgia syndrome. Arthritis Rheum. 2000; 43(11): 2493-2500. doi: 10.1002/1529-0131(200011)43:11<2493::AID-ANR17>3.0.CO;2-W.

63.

Unal-Ulutatar

Ozsoy-Unubol

. The relationship of centralized pain in fibromyalgia syndrome with sleep, fatigue and quality of life. Mod Rheumatol. 2023; 33(1): 224-228. doi: 10.1093/mr/roac002.