Introduction: Transcutaneous electrical nerve stimulation (TENS) is used to reduce pain. TENS is applied as conventional TENS (50-100 Hz, causing paraesthesia) or acupuncture-like TENS (AL-TENS). AL-TENS is inconsistently characterised and research comparing its hypoalgesic effects to conventional TENS is lacking. Aim: To compare the hypoalgesic effects of acupuncture-like transcutaneous electrical nerve stimulation (AL-TENS) and conventional TENS.

BACKGROUND: Shoulder girdle pain is a common disabling complaint with a high lifetime prevalence. Interventions aimed at decreasing shoulder pain without stressing shoulder girdle structures have the potential to improve participation in multimodal shoulder rehabilitation programs. HYPOTHESIS/PURPOSE: The aim of this study was to determine the acute effects of moderate intensity lower extremity exercise on mechanically induced shoulder pain in individuals without shoulder injury. It was hypothesized that participants would exhibit less shoulder pain, as indicated by increased pain thresholds, following lower extremity exercise. STUDY DESIGN: Repeated measures study. METHODS: Thirty (30) healthy participants were recruited to participate in this study. Pain pressure algometry was used to mechanically induce shoulder pain over the infraspinatus muscle belly. This was performed on the dominant shoulder before and immediately after performing 10 minutes of moderate intensity lower extremity exercise using a recumbent exercise machine. Heart rate and rate of perceived exertion were measured following exercise. Repeated measures ANOVA was used to compare pain pressure threshold scores between the baseline and post-exercise time points. Significance was set at p ≤ 0.05 . Effect size (ES) was calculated using Glass's Δ. RESULTS: Moderate intensity lower extremity aerobic exercise led to significantly (F = 8.471, p = 0.003) decreased evoked shoulder pain in healthy adults with moderate effect sizes (0.30-0.43). CONCLUSIONS: Lower extremity aerobic exercise significantly decreased pain of the infraspinatus in this sample of young healthy participants. Utilization of lower extremity exercise may be of benefit for younger patients to decreased acute shoulder pain. LEVEL OF EVIDENCE: 2b: individual cohort study.

A significant driver of pain in low back pain (LBP) is alteration to endogenous pain modulation (EPM). EPM can be measured using quantitative sensory tests (QST), which provides important information on nociceptive pathways. Exercise therapy is recommended as the first line of care for LBP; however, there is limited information on the mechanisms of action that lead to symptom improvements. The first manuscript was a scoping review that summarized protocols used to assess EPM using QST such as pain pressure threshold (PPT), temporal summation (TS), conditioned pain modulation (CPM) or exercise-induced hypoalgesia (EIH) in LBP. Scientific databases were searched for articles that used QST or EIH protocols in LBP. In total, 193 studies were included in this review: 172 used PPT, 54 used TS and 53 used CPM and 5 investigated EIH. There was high variability in the type of equipment, timing, trials, and testing location with many studies not reporting this information. The results demonstrate a need for standardized protocols and reporting guidelines as well as further research to aid in selecting the most appropriate QST parameters for different clinical presentations. The second manuscript was a pilot study that assessed the feasibility of a protocol investigating if changes in EPM occur after exercise therapy. Participants were recruited through a larger trial (WELBack) and were randomized to receive one of two exercise therapies. Participants attended two testing sessions (before and after an 8-week treatment) consisting of PPT, TS, CPM and EIH. Thirty-six participants were recruited and completed baseline assessments. In total, 32 (88.9%) participants completed the follow-up assessment. The results demonstrated that the protocol was feasible. Improvements to patient reported outcomes were seen, but not to all EPM measures. Future work should consider changes to the CPM protocol, and a fully powered study to investigate EPM changes after exercise therapy. / Thesis / Master of Health Sciences (MSc) / Low back pain (LBP) may occur because of changes in our nervous system, rather than a physical injury. However, there is no previous research on if exercise can improve these changes. The purpose of this thesis was to develop and test a protocol to assess how the body processes pain, and if this can change after exercise. We summarized past research on how four tests to assess pain processing have been performed. The results showed many differences in how these tests were performed and reported. More consistency and guidelines are needed to improve how these tests are conducted. Next, we conducted a study aimed to assess the feasibility of a protocol to see if changes occur in how the body processes pain after an exercise therapy program. The results of this study showed the protocol was feasible, and trends in improvement on some but not all measures.

Exercise-induced hypoalgesia (EIH) denotes the phenomenon wherein physical activity induces a diminished sensitivity to pain, holding significant implications for pain management modalities. This investigation sought to evaluate the reproducibility of pressure pain thresholds (PPT) subsequent to dynamic resistance exercise and juxtapose PPT measurements during periods of quiet rest against those immediately post-exercise. A cohort of five healthy participants underwent three separate sessions, wherein PPT assessments were conducted pre- and post-exercise. Findings revealed a nuanced reliability in PPT measures during EIH evaluation, necessitating judicious interpretation due to the constrained sample size. Comparative analyses with antecedent research underscored discernible disparities in exercise intensities and methodological approaches, accentuating the imperative of considering idiosyncratic responses and procedural distinctions. Despite inherent limitations, notably the modest sample size, this inquiry furnishes valuable insights into the intricacies of EIH assessment, elucidating the complexities inherent in advancing knowledge within the domain of pain modulation research. Prospective investigations with larger and more heterogeneous cohorts are imperative to fortify the dependability and generalizability of findings in this realm.

This study assessed the effect of an eight-minute cycling intervention using varying intensities on exercise-induced hypoalgesia (EIH). Generally, current research examines EIH using protocols that last for more than 10 minutes and reach 75% of an individual's VO2 peak. The main objective of this study was to examine the effect of varying intensities on pressure pain threshold (PPT) and heat pain threshold (HPT) at the thigh and forearm, tested pre- and post-cycling intervention. Healthy male participants (n=16) performed a graded exercise test on a cycle ergometer to establish their peak power output (PPO). In subsequent visits, participants completed five different 8-minute cycling interventions, with intensities randomly assigned to one of three counterbalanced orders. HPT and PPT were applied to the thigh and forearm two times before and after each cycling intervention. Additionally, there was a notable effect of intensity on PPT in the thigh, with significant changes at intensities of 90% (p = 0.024) and 100% (p = 0.003). In the forearm, repeated measures ANOVA indicated that there was no significant interaction or main effect for intensity and time. Similarly, for HPT, the analysis did not show significant interaction or main effects for both intensity and location. This study was the first to examine EIH using an 8-minute cycling intervention on a cycling ergometer at individualized intensities. Higher intensity cycling sessions generated EIH locally in the thigh using PPT. This intervention appeared to target the nociceptors activated by mechanical, rather than thermal stimuli, further highlighting the multi-faceted nature of EIH. A short but high intensity cycling intervention may have clinical relevance, as it can provide an intervention to reduce localized pain immediately after exercise using a pressure pain stimulus.

Exercise-induced hypoalgesia (EIH) is the reduction in pain sensitivity following exercise. High-intensity or prolonged exercise is typically required to elicit an EIH response, but there is limited evidence suggesting that low-load resistance exercise with blood flow restriction (LL+BFR) may be able to elicit a robust EIH response. The purpose of these investigations was to assess the magnitude, duration, and proposed mechanisms of EIH following LL+BFR, LL with normobaric systemic hypoxemia, BFR only without exercise, high-load exercise, and a control intervention. The first study evaluated local and systemic pain pressure threshold and tolerance responses one-hour post-exercise. The results indicated that LL+BFR induced similar EIH responses to high-load resistance exercise 0- and 15-minutes post-exercise but only LL+BFR elicited an EIH response present 60-minutes post-exercise. The second study evaluated neuromuscular and perceptual responses, both proposed EIH mechanisms, during exercise. Similar neuromuscular responses were observed in all interventions. Participants reported higher ratings of perceived exertion during LL+BFR and high-load exercise, and higher levels of perceived pain during LL+BFR. These results suggested that despite high levels of motor unit recruitment, there were divergent EIH responses. However, increased pain during exercise may be a mediating factor of EIH after resistance exercise. The third study evaluated peripheral and central cardiovascular responses, which have also been hypothesized to mediate EIH. LL+BFR resulted in greater increases in systolic blood pressure during the first set of exercise, and diastolic blood pressure during all sets of exercise. LL+BFR and BFR only attenuated changes in heart rate variability (HRV). LL+BFR induced the largest increase in deoxyhemoglobin and total hemoglobin and lowered tissue saturation index. BFR only progressively increased oxyhemoglobin and total hemoglobin levels. The local and systemic cardiovascular responses suggested that prolonged EIH following LL+BFR could be related to increased central or peripheral cardiovascular stress.

Orientador: Sebastião Gobbi / Banca: Anderson Saran Zago / Banca: José Luiz Riani Costa / Resumo: O objetivo do estudo foi investigar o efeito agudo de diferentes sessões de exercício físico com pesos na sensibilidade à dor de idosas hipertensas e normotensas. A amostra foi constituída por 21 mulheres idosas (10 normotensas e 11 hipertensas). Após a determinação das cargas no exercício puxada costas e leg press, duas sessões experimentais foram realizadas, adotando-se uma das duas diferentes intensidades 90% ou 100% de 15 repetições máximas (RM). A sessão com 100% de 15 RM envolveu a realização de três séries até a fadiga muscular, a de 90% duas séries de 15 repetições e a terceira série até a fadiga muscular. Antes e imediatamente após as sessões de exercícios as idosas foram submetidas a testes de sensibilidade à dor durante dois minutos, por meio de um instrumento de pressão no dedo. As avaliadas relataram a intensidade da dor através da escala de CR10 de Borg. Aferições de pressão arterial (PA) foram realizadas em repouso, durante, pré e pós-sessões de exercícios com pesos. Os resultados mostraram uma menor sensibilidade à dor em idosas hipertensas após o exercício agudo com pesos a 90% (p=0,048) e 100% (p=0,043) de 15 RM, e independente de serem hipertensas ou normotensas no exercício a 100% (p=0,011), mas não a 90% de 15 RM. Contudo, quando a análise é feita por grupos, a sensibilidade à dor reduziu em idosas hipertensas em resposta, tanto ao exercício agudo com pesos a 100% como a 90% de 15 RM, no entanto esses valores não foram significativos. Esta pesquisa deve contribuir de forma significativa fornecendo subsídios para o desenvolvimento de outros experimentos que possam esclarecer melhor o papel da atividade física na relação dor e hipertensão, sobretudo para mulheres idosas e hipertensas praticantes de exercícios com pesos / Abstract: The aim of this study was to investigate acute effects of different resistance exercise sessions in pain sensitivity in elderly hypertensive and normotensive. The study sample consisted of 21 elderly women (10 normotensive and 11 hypertensive). After determining the loads in the exercise pulley back and leg press, two experimental sessions were held, adopting one of two different intensities 90% or 100% of 15 repetition maximum (RM). A session with 100% of 15 RM involved performing three sets until muscle fatigue, while 90% of 15 MRI performed two sets of 15 repetitions and the third sets to muscular failure. Before and after resistance exercise sessions, the elderly were tested for sensitivity to pain for two minutes, through the instrument of finger pressure. Evaluated the pain intensity reported by the Borg CR10 scale. Measures of BP were performed at rest before and after resistance exercise sessions. The results revealed that the hypertensives showed less sensitivity to pain after the resistance exercise session at 90% RM 15 (p = 0.048), while the normotensives, the difference was not significant (p = 0.763). For the session to 100% 15 RM, pain sensitivity in the hypertensive group was significantly lower (p = 0.043) after the completion of the resistance exercises. However, for the normotensive group, although it has reduced sensitivity to pain during post-exercise values were not significant (p = 0.082). Acute resistance exercise of 100% 15RM significantly decreased sensitivity to pain in both acute resistance exercise at 100% as 90% 15 RM elderly women and hypertensive, however these values were not significant. This research should contribute significantly by providing subsidies for the development of other experiments that might clarify the role of physical activity in relation pain and hypertension, especially for elderly women with hypertension and practicing resistance exercises / Mestre

Background: Emerging evidence suggests that aerobic exercise and conditioned pain modulation may be advocated in treating patients with musculoskeletal pain. The effects of lower extremity aerobic exercise and conditioned pain modulation on evoked shoulder pain are not known. Purpose: To determine the acute effects of lower extremity aerobic exercise and conditioned pain modulation on outcomes of evoked shoulder pain from pain pressure threshold measurements. Study Design: Repeated measures. Methods: Thirty (30) healthy volunteers were tested over the course of two sessions. Session 1 consisted of collecting pain pressure threshold measurements over the infraspinatus before and immediately following a conditioned pain modulation with cool water. Session 2 consisted of collecting pain pressure threshold measurements over the infraspinatus before and immediately following a bout of lower extremity aerobic exercise on a recumbent stepper apparatus. Results: Pain pressure threshold was not significantly influenced by the conditioned pain modulation using cool water (p=0.725). Pain pressure threshold was significantly increased immediately following the lower extremity exercise session (P<0.001). Conclusion: Conditioned pain modulation with cool water did not produce any significant changes in pain pressure threshold. Lower extremity aerobic exercise acutely increased pain pressure threshold in participants with experimentally induced shoulder pain. Physical therapists may consider lower extremity aerobic exercise to produce short-term hypoalgesic effects and facilitate the application of more active interventions.

La manipulation vertébrale (MV) est l'une des options dans le traitement des douleurs d'origine neuromusculosquelettique. Ses indications ont été identifiées à partir de l'expérience des professionnels qui l'utilisent, ainsi que des études épidémiologiques autour de ses résultats cliniques. Cependant, son mécanisme d'action précis demeure à ce jour inexpliqué.La littérature scientifique sur ce sujet est incomplète, éparse et confuse. Certains auteurs et professionnels proposent des hypothèses des mécanismes d'action neurobiologiques et d'autres biomécaniques. De plus, l'étude de la douleur rend la situation difficile en raison de la complexité des situations cliniques et des traitements associés dont les patients bénéficient. C'est la raison pour laquelle l'objectif de cette thèse est d'étudier si la MV a un effet sur la douleur provoquée de manière expérimentale. Si tel est le cas, il importe de savoir s'il est systémique ou locorégional et dans cette dernière hypothèse, si ce résultat est le produit d'une action directe de la MV sur la douleur ou secondaire à une amélioration du mouvement. N'ayant pas trouvé d'étude englobant la problématique mixte des effets de la MV sur la douleur et le mouvement, nous avons procédé à deux revues systématiques et critiques de la littérature scientifique ; l'une a porté sur son effet sur la douleur et l'autre sur l'amplitude du mouvement des segments vertébraux. Dans la première, nous avons rassemblé 22 articles décrivant 43 essais cliniques montrant un effet hypoalgésique de la MV au niveau locorégional, mais les résultats diffèrent selon la manière dont la douleur a été provoquée. Nous n’avons pas pu tirer de conclusion sur l'action systémique de la MV du fait de la qualité des articles sur ce sujet. Quant à la revue de la littérature réalisée sur l'effet de la MV sur l'amplitude du mouvement, l'étude de 15 articles ne nous a pas permis de prouver l'efficacité de cette technique pour augmenter l'amplitude des mouvements segmentaires, malgré des limitations à prendre en considération, notamment le fait que ces études ont été réalisées sur des volontaires sains et non sur des patients avec une mobilité réduite. A partir de là, nous concluons que l'effet de la MV sur la douleur est plutôt direct, et défendons la thèse que l'hypoalgésie induite par la MV permet l'amélioration et la récupération de la fonction de mouvement, et non l'inverse.Cependant, même si nous répondons à nos questions de recherche, ces réponses demeurent partielles et le sujet reste à approfondir. Nos deux revues indiquent qu’il reste à clarifier : les mécanismes exacts des effets de la MV sur la douleur, la durée des effets, les rapports "dose/effet", l'identification des techniques les plus efficaces, ou encore, sur le ciblage plus fin des patients à traiter. Il en est de même en ce qui concerne l'étude de l'effet de la MV sur l'amplitude du mouvement, où il manque notamment des études réalisées sur des patients et des personnes présentant des mouvements limités. Des améliorations sont également à prévoir dans la coordination des chercheurs les rassemblant autour d'une politique de recherche partagée sur le long/moyen terme, et à partir d'un consensus méthodologique, particulièrement en termes de suivi des essais, d'unités de mesures, de précision des critères de qualité des essais, de promotion de méta-analyses, etc. Au total, si la MV semble avoir un effet direct sur la douleur, il n’en demeure pas moins que la connaissance détaillée de ses mécanismes et des modalités d'application dans la pratique clinique reste à approfondir, ce qui pourrait devenir un véritable enjeu pour la communauté des chercheurs, des enseignants et des cliniciens. / Spinal manipulative therapy (SMT) is one of the treatments used to reduce musculoskeletal pain. Some clinical studies have shown that it really has a pain reducing effect but the indications for when it should be used is mainly based on clinical experience and logic. Further, although SMT is widely used, the precise mechanisms of action that can explain how it works, are unknown.We noticed that the scientific literature on this subject is incomplete, scattered and confused. In relation to the mechanisms, some authors propose a number of neurobiological mechanisms (such as a direct reduction of pain) whereas others are convinced that the mode of action is biomechanical (such as improved range of motion). For this reason, when trying to find out if SMT has a pain reducing effect, a better alternative is to start with healthy people, provoke a pain experimentally, perform the SMT, and measure their pain, to see if it has improved with the “treatment”. If it would be possible to see if SMT does have a pure pain reducing effect, then it would be important to find out if this effect is only regional, in the area of the manipulation, or if this effect is systemic. Also, none of the authors who proposed the biomechanical theory offered any evidence that improved movement results in less pain, but then, the opposite pathway (reduce pain first, better movement after) has not been shown either, by these proponents of theories. For this reason we decided to study the already existing scientific literature in a critical and systematic fashion.Unfortunately, we did not find any study including the mixed problem of the effects of SMT on pain and movement, we therefore performed two systematic reviews of the scientific literature: one focused on its effect on experimental pain and the other on its effect on the range of motion (ROM) of the vertebral segments. In the first one, we collected 22 articles describing 43 trials showing an hypoalgesic effect of the locoregional level. Interestingly, the results differ depending on how the pain was provoked. We were not been able to reach a conclusion on the systemic action of the SMT because of the lack of quality of articles on this topic. Concerning the literature review on the effect of SMT on ROM, the review of 15 research articles did not allow us to « prove » the effectiveness of this technique to increase the range of segmental motion. There were some limitations with these studies, such as the fact that they had been performed in healthy volunteers and not in people with reduced mobility. In sum, we could conclude that the effect of SMT on pain has been clearly shown, which supports the hypothesis that the hypoalgesia induced by SMT allows the improvement and recovery of function of movement, and not the inverse. These results have been reported in our two scientific articles.However, even if we were able to obtain answers to our research questions, these answers are incomplete and the subject remains to be further explored. There are still questions that remain to be clarified, such as: What are the exact effects of SMT on pain mechanisms? How long does the effect remain ? Is there a " dose / effect "? Which are the most effective SMT techniques? and How should patients be best targeted for this treatment ? Does SMT have an effect on ROM on people with limited movement?Finally, a coordination of research is necessary to move forward more effectively. Researchers would need to gather around a shared policy in relation to the medium / long term research, and from a methodological consensus. In conclusion, SMT does seem to have a direct effect on pain. However, we need some more and detailed knowledge of the mechanisms and procedures before we can really apply this knowledge efficiently in clinical practice. No doubt, this could become an important issue for the community of researchers, teachers and clinicians.

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