Effects of foam roller on pain intensity in individuals with chronic and acute musculoskeletal pain: a systematic review of randomized trials

Objective To analyze the effects of using foam roller on pain intensity in individuals with chronic and acute musculoskeletal pain. Methods This systematic review was registered in the National Institute for Health Research’s prospective online registry of systematic reviews (PROSPERO) under CRD42023456841. The databases Pubmed, Medline (via Ovid), Embase, BVS, and PEDro (Physiotherapy Evidence Database) were consulted to carry out this systematic review. Notably, the records of clinical trials characterized as eligible were manually searched. The search terms were: (foam rolling OR foam rolling vibration) AND (acute musculoskeletal pain) AND (chronic musculoskeletal pain). The search was performed until August 22, 2023. For the analysis of the methodological quality, the PEDro scale was used for each of the manuscripts included in the systematic review. Due to the heterogeneity in the studies included in this systematic review, performing a meta-analysis of the analyzed variables was impossible. Results Only six manuscripts were eligible for data analysis. The type of FR used was non-vibrational, being applied by a therapist in only one of the manuscripts. With an application time ranging from at least 45 s to 15 min, the non-vibrational FR was applied within a day up to six weeks. Using the PEDro scale, scores were assigned that varied between 4 and 8 points, with an average of 6 ± 1.29 points. Only two randomized clinical trials found a significant benefit in pain intensity of adding FR associated with a therapeutic exercise protocol in individuals with patellofemoral pain syndrome and chronic neck pain. Conclusion The results of this systematic review do not elucidate or reinforce the clinical use of FR in pain intensity in individuals with chronic and acute musculoskeletal pain.


Introduction
Foam roller (FR) is a popular self-massage or self-myofascial release technique.It involves using a foam roller, a tube-shaped device composed of or surrounded by foam, to apply pressure on the affected body parts [1].FR has been found to have various benefits for athletes and individuals engaged in physical activity.One of the main benefits of FR is its ability to reduce muscle soreness and improve recovery.FR reduced muscle soreness and increased voluntary muscle activation, vertical jump height, and flexibility compared to a control group [2].Similar to these findings, the meta-analysis by Wiewelhove et al. [3] concluded that FR could alleviate muscle fatigue and soreness, making it an effective intervention for post-exercise recovery.
FR has also improved range of motion (ROM) and flexibility.Promises significant increases in knee-joint ROM after just two 1-minute [4].Another study by Shu et al. [5] highlighted the physiological benefits of FR, including improved ROM, reduced risk of sports injury, and shortened recovery period [5].In addition to its effects on muscle soreness and flexibility, FR has been found to have neurophysiological effects.Young et al. [1] investigated the effects of roller massage, which includes foam rolling, on spinal excitability and found that it decreased spinal excitability in the soleus muscle [1].This suggests that FR may have a positive impact on the neuromuscular system.
Despite the reported clinical effects, there is a clear need for further research to fully elucidate the specific physiological mechanisms underlying the effects of FR.Despite this context, some physiological effects have been reported over the last few years.Among the most prominent is the constant tension on soft tissues, which overloads the skin receptors, modulating pain, and stretching.Increased local blood flow promotes the modulation of inflammation in the fascia.Increase in circulating neutrophils and the activity of alpha motor neurons, and a decrease in neural inhibition, facilitating the communication of afferent receptors in the connective tissue [6].
Specifically, FR has improved blood circulation and arterial function.Pablos et al. [7] observed increased blood flow and muscle oxygen saturation after foam rolling, contributing to tissue healing and muscle recovery [7].Additionally, FR has been shown to decrease arterial stiffness and increase nitric oxide concentration, further supporting its positive effects on arterial function [7].
Overall, FR is a beneficial technique for athletes and individuals engaged in physical activity.It can help reduce muscle soreness, improve recovery, increase range of motion and flexibility, and positively affect the neuromuscular system and arterial function.Incorporating FR into a regular exercise routine may enhance performance and prevent injury.Among the various physiological mechanisms proposed to justify the use of FR, attention is drawn to the one that highlights the modulation of pain in the central nervous system using FR.The pressure exerted by the FR on the soft tissues would promote an overload on the skin receptors, causing the inhibition of pain sensation and tolerance to stretch [8][9][10][11].
However, although a clear physiological relationship exists, the potential effects and clinical benefits of using FR for pain in acute and chronic musculoskeletal conditions have yet to be fully elucidated.Mainly because, to date, previously published systematic reviews, with or without meta-analysis, on the use of FR have included the analysis of healthy participants.Therefore, they did not explore FR's effects and clinical repercussions on pain intensity in individuals with acute or chronic musculoskeletal conditions.These gaps, added to the growing clinical use of FR, justify the preparation and carrying out of this systematic review.
Therefore, this study aims to systematically review the literature on the effects of using FR on pain intensity in individuals with chronic and acute musculoskeletal pain.Thus, this review hypothesizes that using FR associated with exercise protocols improves pain intensity in individuals with chronic musculoskeletal conditions.

Methodology
This systematic review was carried out based on the guidelines provided by PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) [12].It was registered in the National Institute for Health Research's prospective online registry of systematic reviews (PROSPERO: https://crd.york.ac.uk/PROS-PERO/) under CRD42023456841.
Systematic searches were performed in the following databases: Pubmed, Medline (via Ovid), Embase, BVS, and PEDro.Notably, the records of clinical trials characterized as eligible were manually searched.
The search terms were: (foam rolling OR foam rolling vibration) AND (acute musculoskeletal pain) AND (chronic musculoskeletal pain).The search terms were defined by taking previously published systematic reviews as an example [3,13,14].The date of the last survey was August 22, 2023.

Eligibility criteria
Studies were considered for inclusion if they met the criteria: • Randomized Clinical trials.
• Published in a peer-reviewed journal.• English language.
• Individuals with chronic and acute musculoskeletal pain.The diagnosis of chronic pain was consistent with the British Pain Society definition (chronic pain that lasts beyond the time that tissue healing would usually be expected to have occurred, often taken as ≥ 3 months).The diagnosis of acute pain was consistent with the British Pain Society definition, often taken as ≤3 months) [15].

Identification and selection of studies
The study screening process started with reading the titles and abstracts of the manuscripts.The potentially eligible manuscripts were read in total to complete the eligibility check.
In this way, a standardized data extraction form was used.The following data were extracted: Number of participants/gender, age, sample characteristics, evaluation time, pain assessment, therapy program, frequency of treatment, experimental group, control group, type of foam roller, characteristics of a foam roller, time, application mode, body region, combined therapy, characteristics, duration of treatment, control group post-intervention (mean ± standard deviation), experimental group post-intervention (mean ± standard deviation), results, conclusions.
Finally, an analysis of the methodological quality of the included studies was performed using the PEDro scale.Of 11 items, 10 are scored (items 2 to 11).The items are Random allocation, Concealed allocation, Baseline comparability, Blind subjects, Blind therapists, Blind assessors, Adequate follow-up, Intention-to-treat analysis, Between-group comparisons, Point estimates, and variability.The PEDro scale has good levels of validity and reliability, where higher scores mean higher methodological quality [16][17][18].Scores for included manuscripts were taken directly from the PEDro database whenever possible.For the screening process, data extraction, and methodological quality analysis, when articles were not found or the score was not established, two independent (CAFDP and ISS) trained reviewers evaluated the article using the PEDro scale.In disagreement, a third reviewer (AVDF) was consulted to provide a consensus.

Data analysis
Data on pain intensity and musculoskeletal pain variables were extracted from the studies selected for inclusion and structured according to their follow-up times.Time of follow-up was defined as immediately after treatment (≤ 1 day); short (up to 4 weeks), medium (up to 12 weeks), and long (> 12 weeks).To analyze the effect of interventions on pain intensity variables, the mean difference between the groups and the 95% confidence intervals for each study were extracted.When the study did not present the mean difference between the groups and the confidence intervals, both were calculated using the confidence interval calculator provided by PEDro.
Due to the heterogeneity in the studies included in this systematic review, performing a meta-analysis of the analyzed variables was impossible.

Description of studies
The studies included in the systematic review were published between 2018 and 2023.Altogether, the included manuscripts include the participation of 234 individuals (111 female, 121 male) with an average of 39 ± 7.23.With a minimum of 30 and a maximum of 50 individual study participants.With an age range between 17 and 74 (Table 1).
Most manuscripts (5 of the 6) consisted of individuals with chronic musculoskeletal pain: Unilateral patellofemoral pain syndrome [19], Non-specific low back pain [21], Chronic neck pain [23], Plantar fasciitis [20,22].In only one of the manuscripts [24], the individuals had a condition characterized as acute pain established by total knee arthroplasty resulting from osteoarthritis.

Methodological quality
Only two manuscripts [22,24] did not have scores reported in the PEDro database.For this reason, two independent reviewers used the PEDro scale to score these manuscripts.
Using the PEDro scale, scores were assigned that varied between 4 and 8 points, with an average of 6 ± 1.29 points (Table 2).The PEDro scale criteria: random allocation, baseline comparability, adequate follow-up, point estimates, and variability were scored in all manuscripts, specifically about the criteria between-group comparisons and Intention-to-treat analysis.For the first, no score was assigned in only one of the manuscripts [23].Regarding the second, only one manuscript received a score [23].The criteria: Blind subjects, therapists, and Intention-to-treat analysis were not scored in any of the included manuscripts.

Interventions
The type of FR used was non-vibrational, being applied by a therapist in only one of the manuscripts [24].With an application time ranging from at least 45 s [20] to 15 min [23], the non-vibrational FR was applied within a day [20] up to six weeks [21] (Table 3).

Outcomes measures and effect of interventions
At short-term follow-up, three studies [19,23,24] compared the use of FR associated with a therapeutic   [19,24], and versus therapeutic guidelines [23].The following scales were used: VAS (10 cm) [19,23], and VAS (0-100 mm) [24].Kumar et al. [19] and Cabrera-Martos et al. [23] showed a statistically significant reduction in pain intensity when using FR associated with a therapeutic exercise program.Presenting, respectively, the values MD 2.4 (95% CI 1.94 to 2.86, and MD 2 (95% CI 0.64 to 3.36) (Table 4).Also, at a short follow-up using the VAS, Hameed et al. [22] compared the use of FR associated with therapeutic ultrasound versus FR placebo with therapeutic ultrasound.However, no statistically significant differences between groups were reported (Table 4).
At medium-time follow-up, Ozsoy et al. [21] compared the use of FR associated with a multimodal protocol of therapeutic interventions versus a multimodal protocol of therapeutic interventions.Using the VAS at rest and during activity scale for this.However, no statistically significant differences between groups for pain intensity at rest and during activity were found (Table 4).
Ranbhor et al. [20] was the only study that compared FR without associations versus therapeutic allotment at immediate time follow-up using the VAS (10 cm).However, no statistically significant difference between groups was found (Table 4).

Discussion
This review had the practical objective of summarizing the evidence on the effect of FR in individuals with chronic and acute musculoskeletal pain.Given the reviews previously carried out on the use of FR for indirect markers of muscle damage in healthy individuals [24], movement, muscle recovery, and performance [3,13,14,[26][27][28][29], range of motion for ankle dorsiflexion in healthy adults [30], Motion, muscle recovery, performance associated with exercise programs focused on stretching [31,32] and use of vibrational FR on the range of motion and performance of normal individuals [33,34].This is the first systematic review that summarizes the results of studies using vibrational or non-vibrational FR on the outcome variable pain intensity in individuals with chronic and acute musculoskeletal pain.
Thus, of the six clinical trials included, four were characterized as short-term follow-ups [189 22, 23, 24], one medium-time follow-up [21] and immediate time follow-up [20].Five used FR associated with other types of therapeutic exercise.Three randomized clinical trials estimated the effect of FR associated with a therapeutic exercise protocol [19,23,24].Ozsoy et al. [21], used a multimodal therapeutic intervention protocol.Ranbhor et al. [20], used it associated with a stretching exercise protocol.Hameed et al. [22], associated with therapeutic ultrasound.Only Ranbhor et al. [20] used FR without associations with other interventions or therapeutic protocols.However, only two randomized clinical trials found a significant benefit in pain intensity of adding FR associated with a therapeutic exercise protocol in individuals with patellofemoral pain syndrome [19] and chronic neck pain [23].
Despite the benefits found in using FR associated with a therapeutic exercise protocol, there is a notable mix of the applicability of FR.Both used the VAS (10 cm) for evaluation, self-application, non-vibrational FR, and four weeks to carry out the interventions in individuals with two conditions related to chronic pain.The exposure intensities of the interventions were highly different, with ten daily repetitions [19] and 3 days per week [23].This makes it unfeasible and challenging to define the best periodicity for the applicability of FR to reduce pain intensity.However, it demonstrates that better results from applying FR may be conditioned by therapeutic exercise protocols with a longer therapeutic window of exposure of at least four weeks.
The results highlighted in this review confirm the applicability trend of FR associated with therapeutic exercise protocols, such as stretching [31].However, a recent systematic review and meta-analysis Konrad et al. [32] attested to significant heterogeneity in the applicability parameters of the FR in the studies analyzed, also found in this review.Furthermore, using FR and stretching protocols does not cause additional effects on the range of motion, only in athletes' performance (e.g., strength, speed).Therefore, these results, added to the results presented in this systematic review on pain intensity, may be fundamental for structuring new clinical trials aiming to analyze the effects of FR associated with therapeutic exercise protocols based on stretching or muscle strengthening.The analysis of variables related to pain behavior, performance, and/or functional capacity in individuals with chronic musculoskeletal conditions should be taken as a basis.However, these new studies must attempt to standardize the time and intensity of FR applicability.
Far beyond the diversity of characteristics related to the applicability of the FR, it was possible to verify that, on average, randomized clinical trials had a methodological quality between fair and good on the PEDro scale [35].However, in addition to the PEDro scale criteria, it should be noted that the manuscripts should have reported the prior registration of study protocols.Four of the six manuscripts [20,21,23,24] described the sample size calculation.However, the previous description of these studies' sample calculations must be completed.These methodological characteristics provide critical gaps regarding the transparency of the protocols used and even the existence of a relevant sampling power to reject or accept the hypotheses formulated by these studies.
When observing the results of the most recent systematic reviews on using FR, it is possible to attest to a mixed bag of results.The use of FR did not demonstrate any detrimental effect on improving flexibility.However, it appears to be effective for increasing the range of motion in a healthy adult population in the short term, up to 30 min [30].And yet, even without promoting changes in markers related to indirect recovery from muscle damage (muscle pain, range of movement, muscle swelling, and maximum voluntary isometric contraction) in healthy individuals.It has excellent potential to increase jumping performance, agility, and strength and improve recovery Alonso-Calvete et al. [34] despite the absence of significant changes in performance when FR training is applied over one or several weeks [6,36].However, what stands out about these results is that they were based on the analysis of healthy individuals.Therefore, without health conditions that limit movement, flexibility, or functional performance.The results presented in this review, even if embryonic and preliminary, can be encouraging for the promotion of new randomized clinical trials aimed at using RF for acute and mainly chronic musculoskeletal conditions such as patellofemoral pain syndrome analyzed by Kumar et al. [19] and Chronic neck pain by Cabrera-Martos et al. [23].
Although limited and reinforces the need for more solid evidence for using FR concerning pain intensity, the results of this review provide space for future studies.Mainly, randomized clinical trials aimed at using FR to analyze pain-related variables in individuals with musculoskeletal conditions and with the appropriate size of participants.Using FR in the multimodal intervention context, therapeutic exercise protocols based on muscle strengthening or stretching are applied long-term, greater than or equal to 4 weeks.Seeking to structure the form of application between 1 and 15 min.With comparisons of the applicability of FR before or after therapeutic exercise protocols based on muscle strengthening or stretching.And with the confrontation of types of FR, non-vibrational versus vibrational.Finally, this review was conducted with searches in prominent research bases.However, not all databases available in the literature were used due to territorial access impossibilities.We recommend that future reviews structure a broader and more complete search using as many research bases as possible.

Conclusion
Despite being promising and opening space for new studies, the results of this systematic review do not elucidate or reinforce the clinical use of FR in pain intensity in individuals with chronic and acute musculoskeletal pain.

Fig. 1
Fig. 1 Selection of studies for inclusion in the systematic review

1 =
Yes, * Not reported on PEDro

Table 1
General characteristics of the studies included NR: Not reported, SLR: Straight leg raise technique, VAS: Visual analog scale, PPT: Pain Pressure Threshold, cm: centimeters, mm: millimeters, TENS: transcutaneous electrical stimulation, µs: microsecond, secs: seconds, W: Watts, Hz: Hertz, FR: Foam roller, reps: repetitions, ROM: Range of motion exercise program versus a therapeutic exercise program

Table 2
Methodological evaluation of studies with technical specifications by PEDro scale

Table 4
Results and conclusions of studies regarding pain intensity NR: Not reported, VAS: Visual analog scale, FR: Foam roller, ROM: Range of motion, MD: median; CI: confidence interval, CSE: core stabilization exercise, NSLBP: Nonspecific low back pain, mm: millimeters, cm: centimeters, TENS: transcutaneous electrical stimulation