Juan José Amer-Cuenca

Low back pain (LBP) is the most prevalent musculoskeletal condition and leading cause of disability globally. In pregnant women, pain frequently involves lumbar region and pelvic girdle, so the term pregnancy-related lumbopelvic pain (PLPP) is adopted. Biological, psychological, and social factors influence the development and perception of LBP during pregnancy, recognising multidimensional variables such as kinesiophobia, catastrophising, body surveillance, and functionality appreciation. Unlike previous research, this study jointly examined established biopsychosocial factors and underexplored multidimensional constructs, particularly body surveillance and functionality appreciation, in relation to PLPP intensity. The aim of this study was to evaluate the relationship between the intensity of LBP and variables included in the biopsychosocial model, in addition to the creation of an exploratory model to identify the variables with the greatest relative importance for pain classification. A multicentre cross-sectional observational study was conducted in pregnant women aged over 18 years and in the third trimester, with or without PLPP. Pain intensity was measured and categorised into three levels, and sociodemographic, biological, psychosocial, and multidimensional variables were evaluated. 262 pregnant women were included in the study. The variables of BMI, educational level, anxiety and depression, kinesiophobia, and catastrophising showed significant differences in relation to the pain intensity categories. The exploratory model identified BMI and catastrophising as the variables with the greatest relative importance for pain classification. This analysis of LBP in pregnant women showed significant differences in catastrophising, kinesiophobia, BMI, educational level, anxiety, and depression according to their pain levels.

Background and Objectives: Low-volume plyometric conditioning may elicit post-activation performance enhancement (PAPE), but the early response to pogo-jump exercise in adolescent basketball players remains uncertain. This randomized crossover pilot study estimated the effect of adding 24 bilateral pogo jumps to a standardized warm-up on countermovement-jump (CMJ) and drop-jump (DJ) height, compared with time-matched low-intensity walking. Methods: Twenty-seven male basketball players were recruited, and 21 (age, 16.55 ± 0.88 years) completed both conditions. In randomized order, separated by a 7-day washout, participants performed 3 sets of 8 bilateral pogo jumps with 1 min between sets or approximately 3 min of low-intensity walking. Post-condition jump assessments began after a 1 min recovery and comprised three consecutive CMJs, a 30 s transition, and three consecutive DJs, with all measurements completed within approximately 2 min after each condition. The highest valid trial was retained for each jump type. Period-adjusted treatment effects were estimated using separate linear mixed-effects models, with repeated-measures ANOVA and Wilcoxon analyses retained as sensitivity analyses. Results: The period-adjusted between-condition difference in change was −0.89 cm for CMJ (95% CI, −2.92 to 1.14; p = 0.389) and 0.34 cm for DJ (95% CI, −1.77 to 2.45; p = 0.753). Sensitivity analyses yielded the same overall interpretation. All completers performed the protocol, and perceived exertion was 11.4 ± 1.2. The pogo-jump protocol showed favorable immediate tolerability, with all completers reporting 0/10 anterior-knee pain immediately after the condition. Conclusions: The pilot estimates did not indicate a detectable group-level improvement in CMJ or DJ height during the early post-conditioning assessment. However, the confidence intervals were compatible with potentially meaningful effects in either direction. The small sample, single dose, single early assessment window, and variable DJ reliability limit the precision and generalizability of the findings.

Background: The additional value of neuromuscular electrical stimulation (NMES) during contract–relax proprioceptive neuromuscular facilitation (PNF-CR) stretching remains unclear, particularly in adolescent athletes. It is also unknown whether combining PNF-CR with motor-threshold NMES improves hamstring flexibility more than a sensory-threshold comparator without impairing vertical jump performance. Purpose: To compare the acute effects of PNF-CR combined with motor-threshold NMES versus sensory-threshold NMES on hamstring flexibility and to assess the impact of both interventions on vertical jump performance. Study Design: Randomized controlled trial. Methods: Forty-seven youth soccer players (mean age: 13.2 ± 1.8 years) were randomly assigned to one of two groups. Both groups received the same single-session PNF-CR stretching protocol. The experimental group (n = 23) received motor-level NMES during the contraction phases, whereas the placebo group (n = 24) received sensory-level NMES during the same PNF-CR protocol. Hamstring flexibility was assessed using the Popliteal Angle (PA) and Sit-and-Reach (SR) tests, while vertical jump performance was evaluated via the Countermovement Jump (CMJ) test. Analyses followed an intention-to-treat approach. Time, group, and time × group effects were examined using two-way repeated-measures ANOVA with Bonferroni-adjusted post hoc comparisons; CMJ was additionally analyzed using ANCOVA adjusted for baseline values. Results: Both groups showed statistically significant pre–post improvements in SR and PA scores. Specifically, PA decreased in the experimental group by 4.0° (95% CI: 1.4 to 6.5; p = 0.003) and by 3.1° (95% CI: 0.5 to 6.0; p = 0.018) in the placebo group. SR increased by 2.7 cm (95% CI: 1.9 to 3.6; p < 0.001) in the experimental group and 2.8 cm (95% CI: 1.9 to 3.7; p < 0.001) in the placebo group. No significant between-group differences were found for either flexibility outcome. Regarding CMJ, no significant intra- or intergroup changes were observed (p > 0.05). Conclusion: The addition of motor-threshold NMES to a PNF-CR stretching protocol does not yield superior acute flexibility gains. Moreover, neither intervention negatively affected jump performance in this athletic population, supporting their safe and potentially beneficial application in pre-training contexts for adolescent soccer players. Level of Evidence: 1b.

Fibromyalgia (FM) is a chronic condition characterized by widespread pain, fatigue, and diverse physical and psychological symptoms that significantly impair daily functioning. Latest guidelines advocate for a comprehensive approach to FM management, emphasizing patient education, therapeutic exercise, pharmacological treatments, and psychotherapy. Although exercise remains the primary non-pharmacological strategy supported by robust evidence, its clinical implementation faces several limitations, including poor adherence, fear of movement, pain catastrophizing and proprioceptive deficits. Immersive virtual reality (IVR) has recently emerged as a promising adjunctive tool that not only addresses these limitations but also provides additional therapeutic benefits. Specifically, preliminary studies suggest that incorporating visual feedback manipulation through IVR can effectively modify movement perception, potentially enhancing clinical outcomes. This randomised controlled trial aims to assess the efficacy of a fully immersive virtual reality (FIVR)-based therapeutic exercise programme designed to induce implicit visual illusions, making participants perceive less movement than is performed during structured resistance exercises. Eighty participants diagnosed with FM will be recruited and randomly allocated to either the experimental group, which will engage in a structured resistance exercise regimen combined with FIVR, or the control group, performing identical exercises without FIVR. The primary measure will be the impact of FM on daily life, evaluated using the Revised Fibromyalgia Impact Questionnaire. Secondary outcomes include fatigue, sleep quality, FM symptom severity, health-related quality of life, psychological factors, central sensitization, body perception distortion, lower limb strength and handgrip strength, functional mobility, lumbar range of motion, influence of modified visual feedback, behavioural regulation during exercise and overall physical activity levels. This study aims to provide robust evidence regarding the potential benefits of integrating FIVR with therapeutic exercise. Findings could support FIVR as a valuable clinical innovation, potentially yielding superior improvements in daily functioning, physiological outcomes, and psychological well-being compared to traditional exercise interventions alone. ClinicalTrials.gov (NCT06948500). URL: https://clinicaltrials.gov/ct2/show/NCT06948500 .

Background: Transcutaneous electrical nerve stimulation (TENS) is a widely used non‐pharmacological method for pain management, though its effectiveness in individuals with chronic low back pain (CLBP) is uncertain. Previous studies and systematic reviews have not systematically analysed the influence of TENS dosing parameters on treatment outcomes. Objectives: To assess the impact of TENS on pain relief in individuals with CLBP and to explore the dose‐dependent effects of TENS parameters on pain relief. Methods: A systematic review and meta‐analysis was conducted following PROSPERO registration. Searches were performed in PubMed, Cochrane and Scopus databases. A total of 29 studies out of 1162 screened were included. Study quality was assessed using the PEDro scale and RoB‐2 tool. Meta‐analyses using random‐ and mixed‐effects models were conducted. Results: The initial random‐effects model showed no significant effect of TENS on pain ( d ₊ = 0.16, p > 0.050, k = 64) when dosing parameters were not considered. However, moderator analyses comparing TENS with control or placebo groups revealed that appropriate intensity was associated with larger effects than inappropriate intensity (Δ d ₊ ≈0.67; F (1, 16) = 7.27, p = 0.016), with subgroup estimates of d ₊ = 0.97 (95% CI 0.65–1.30; k = 12) versus d ₊ = 0.30 (95% CI −0.11 to 0.72; k = 6). Frequency, number of sessions and electrode placement showed no significant impact. Conclusions: TENS can reduce pain in individuals with CLBP when delivered at a sensory‐level intensity that is clearly perceptible and titrated throughout the session. Fixed intensity and stimulation strong enough to elicit muscle contractions are generally not recommended. These findings support the relevance of dosing in optimising TENS effectiveness. Overall, the certainty of evidence appears low due to the high risk of bias and substantial heterogeneity. Significance Statement: This meta‐analysis provides a comprehensive synthesis of the evidence on transcutaneous electrical nerve stimulation (TENS) for pain relief in chronic low back pain (CLBP), with a specific focus on the role of stimulation parameters as sources of heterogeneity. By systematically examining dose‐related characteristics, particularly stimulation intensity, this work helps clarify why previous reviews have reported inconsistent findings. The results suggest that inadequate dosing may obscure potential analgesic effects, highlighting the importance of parameter reporting and implementation when interpreting existing trials. Overall, this review offers a clinically and methodologically relevant framework to inform the design of future high‐quality trials and to guide more nuanced evaluation of TENS within multimodal CLBP management. Trial Registration: PROSPERO: CRD42023468176

Movement-evoked pain in chronic low back pain (LBP) can be influenced by visual cues linked to threatening movements. This study explored whether manipulating visual proprioceptive feedback via virtual reality (VR) alters movement-evoked pain and if individuals with higher pain, kinesiophobia, disability, or catastrophising are more susceptible to these manipulations. Cross-sectional study with 50 patients with non-specific chronic LBP. Participants performed lumbar spine extension until pain onset with and without VR. VR feedback was manipulated to show 10% less (E −) or 10% more (E +) movement than actual extension. Range of motion (ROM) was measured using an electro-goniometer. Within-group differences across control (E), E −, and E + conditions were assessed with Friedman tests. VR underestimation (E −) led to a 20% increase in ROM compared to the control (E; p = 0.002) and a 22% increase compared to overestimation (E +; p < 0.001). Patients with higher kinesiophobia and disability showed greater improvement in the E − condition. Manipulating visual-proprioceptive information through VR altered pain thresholds in chronic LBP. Underestimated movement (E −) delayed pain onset by extending ROM. Kinesiophobia and disability significantly influenced susceptibility to visual feedback.

Cross-sectional study. Movement-evoked pain may serve as a protective response influenced by visual-proprioceptive cues signaling potentially threatening movements. This study aimed to assess the impact of manipulating visual-proprioceptive feedback using virtual reality (VR) during lumbar flexion on movement-evoked pain thresholds. Additionally, we explored whether individuals with elevated pain, kinesiophobia, and catastrophizing were more susceptible to visual-proprioceptive manipulation. Fifty participants with non-specific chronic low back pain (cLBP) were included. We assessed lumbar flexion-evoked pain thresholds alongside pain levels, pain interference, kinesiophobia, and catastrophizing. Participants performed lumbar flexion movements in three conditions: (1) without VR (control, F), (2) with a virtual illusion shortening the perceived arm length by 20% (understated condition, F−), and (3) with a virtual illusion elongating arm length by 20% (overstated condition, F +). Range of motion (ROM) was measured using an electro-goniometer. One-way ANOVA with Bonferroni post-hoc tests examined differences among conditions, and three two-sample t-tests explored whether individuals with higher pain, kinesiophobia, and catastrophizing were more affected by visual-proprioceptive manipulation. Understating the flexion task (F−) led to a 5% increase in movement compared to the control (P = 0.04; 95% CI [0.6%, 10.7%]) and a 7% increase compared to the overstated condition (F +) (P < 0.001; 95% CI [2.6%, 11.6%]). Additionally, individuals with higher pain levels and pain interference, exhibited a more pronounced response to the understated condition (F−). Manipulating visual-proprioceptive feedback through VR significantly influenced pain thresholds during lumbar flexion in cLBP patients. The understated condition (F−) extended pain-free movement, delaying pain onset. Furthermore, pain intensity and interference modulated susceptibility to visual feedback manipulation. These findings enhance our understanding of how visual-proprioceptive feedback influences pain perception and movement patterns in cLBP. They suggest new avenues for pain assessment, therapeutic interventions, and clinical strategies, particularly for individuals with high pain levels, interference, kinesiophobia, and catastrophizing. This study was retrospectively registered in the ClinicalTrials.gov with identifier NCT06750887

Background: Hamstring muscle injuries are common in basketball and result in long periods of inactivity. To reduce their incidence, preventive protocols, including proprioceptive neuromuscular facilitation (PNF) stretches, have been proposed. The aim of this study is to compare the short-term effects of PNF and PNF + neuromuscular electrical stimulation (NMES) on hamstring extensibility and, secondarily, on vertical jump capacity in young basketball players. Materials and Methods: The study was a randomized controlled trial. One group performed a PNF stretching protocol and the other PNF + NMES. Hamstring extensibility was measured using the Sit and Reach test and the popliteal angle and jump capacity were measured using the Counter Movement Jump, both before and immediately after the intervention. Results: Forty-five young male players participated. Both groups showed significant intra-group improvements (p < 0.001) in hamstring flexibility after the intervention. However, there were no significant intra-group differences (p > 0.05) in jump capacity. Additionally, no significant differences (p > 0.05) were observed between the two groups for any of the measured variables. Conclusions: Both programs are effective in increasing hamstring flexibility in the short term without impairing vertical jump capacity in young basketball players.