The TSK–11, a short version of the Tampa Scale for Kinesiophobia, is commonly used to assess fear of movement and (re)injury in patients with musculoskeletal pain. The two–factor model of the TSK–11, consisting of activity avoidance (TSK–AA) and somatic focus (TSK–SF), is known for its high consistency and reliability. However, the subscales of the Japanese version of the TSK–11 have not been validated, and the differences between them are unclear. The aim of our study is to validate the TSK–J11 subscales in Japanese, investigate their associations with pain and pain–related measures, and identify differences between the subscales using data from our prior studies.

Data were collected from 349 participants in 2018 and 216 in 2020. The measures included the TSK–AA and TSK–SF, pain intensity, sleep disorders, the multidimensional assessment of interoceptive awareness, EuroQol 5 Dimensions, and presenteeism. Reliability was assessed using Cronbach’s alpha, and validity was determined through the confirmatory factor analysis. Correlation analyses were performed to explore the relationships between the subscales and the pain–related variables.

Cronbach’s alpha for the TSK–AA and TSK–SF was 0.72 and 0.71. The TSK–SF was significantly associated with pain intensity, and both TSK–AA and TSK–SF were significantly associated with sleep disorders, lower interoceptive awareness, reduced quality of life, and increased presenteeism.

TSK–AA and TSK–SF were reliable and valid in the Japanese population, exhibiting consistent associations with several pain–related measures. TSK–SF scores were increased in people with pain, while TSK–AA scores were not.

The effects of exercise–induced hypoalgesia (EIH) and the barriers to its effectiveness in elderly individuals aged over 70 years remain unexplored. This study aimed to investigate whether reduced EIH effects are associated with a decline in endogenous pain inhibitory system function and skeletal muscle mass, a key indicator of sarcopenia, in the elderly. Thirty–four individuals aged over 70 years participated in the study. Demographic data, pain intensity (numerical rating scale: NRS), pressure pain threshold (PPT) at the affected hip joint and forearm, conditioned pain modulation (CPM), skeletal muscle mass index (SMI), and sarcopenia status, as defined by the Asian Working Group for Sarcopenia, were assessed. Participants performed 15 minutes of aerobic exercise using a stationary cycle ergometer. EIH effects were defined as the change in NRS and PPT before and immediately after exercise. PPT significantly increased at all measured sites following exercise, but the changes, ranging from 5.7% to 9.8%, were not clinically meaningful. Additionally, NRS showed no significant change. EIH effects, reflected by changes in PPT, were positively correlated with CPM and SMI. These findings suggest that EIH effects are impaired in individuals over 70 years, with a dysfunctional endogenous pain inhibitory system and reduced skeletal muscle mass identified as barrier factors. Exercise interventions targeting sarcopenia and pain modulation may improve pain management strategies for this population.

Introduction: Women often experience cyclical pain outside their menstrual phase, suggesting that hormonal fluctuations influence pain perception. Additionally, the pain modulation system, assessed using pressure pain thresholds (PPT) and conditioned pain modulation (CPM), may contribute to cyclical pain. This study investigated the characteristics of cyclical pain in young women during hormonal fluctuations, excluding menstrual pain, and explored whether pain was more closely associated with menstrual–related symptoms (e.g., autonomic dysregulation, water retention, emotional distress) or dysfunction in pain modulation.

Methods: This cross–sectional study included 40 healthy women with regular menstrual cycles (mean age: 21.3 ± 4.8; range: 18–30). Participants completed three sessions during the early follicular (EF [E/P–]), the late follicular (LF [E+]), and the mid–luteal (ML [E/P+]) phases, when estrogen and progesterone levels significantly fluctuated. Pain– and menstruation–related symptoms were assessed using the menstrual distress questionnaire (MDQ). Pain modulation was evaluated using the PPT and CPM measurements.

Results: The MDQ total pain scores were significantly higher during the E/P+ phase compared to the E/P– and the E+ phases. The subcategory analysis revealed significant positive correlations between pain symptoms and autonomic reactions, water retention, impaired concentration, and negative affect during the E/P+ phase. No significant correlations were found between pain symptoms and the PPT or CPM across all phases.

Discussion: Cyclical pain intensified during the E/P+ phase, when estrogen and progesterone levels fluctuated. The relationship between pain symptoms and menstruation–related factors suggests that hormonal fluctuations, rather than dysfunction in pain modulation, predominantly drive cyclical pain.

Photobiomodulation (PBM) has gained significant attention as a non–invasive and effective treatment for pain. However, the precise mechanisms and quantitative assessment of PBM’s effects remain unclear. This study aimed to develop an in vivo electrophysiological evaluation system to quantitatively measure the effects of PBM, using the firing frequency of neurons in the spinal dorsal horn as an indicator. An 808 nm semiconductor laser was used to irradiate the sciatic nerve in rats, and the neuronal responses evoked by the von Frey filaments were measured. Our findings revealed that PBM significantly suppressed the firing frequency evoked by a 15.0 g von Frey filament, with effects persisting up to 180 min post–irradiation, whereas no changes were observed in the sham group. Additionally, PBM reduced neuronal responses to varying von Frey filament intensities, suggesting a selective effect on noxious stimuli. This evaluation system offers a robust and quantitative method for assessing the effects of PBM, and provides valuable insights into its mechanisms. This tool has the potential to enhance clinical outcomes and improve the chronic pain by providing a precise and reliable means of assessing the efficacy of PBM.

Balneotherapy has been used as complementary therapy for many diseases. In Japan, bath salts from the Myoban Spa, which contains a high concentration of aluminum potassium sulfate, have been approved for its analgesic effects. However, the molecular mechanisms underlying the analgesic effects of these ions have not been reported. We focused on TRPV1 and TRPA1, which are known pain sensors. In this study, we evaluated the inhibitory effects of Myoban bath salts and their components, aluminum potassium sulfate and iron sulfate, on TRPV1 and TRPA1 activity using electrophysiological experiments. We found not only bath salts, but also aluminum potassium sulfate inhibited both TRPV1 and TRPA1 activation in the acidic condition. Our study suggested that aluminum potassium sulfate is the main component responsible for the pain–reducing effect of bath salts from the Myoban Spa.