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Takafumi Hattori,1,2 Satoshi Ohga,3 Kazuhiro Shimo,3 Yuto Niwa,1 Yuji Tokiwa,1 Takako Matsubara1,3 1Faculty of Rehabilitation, Kobe Gakuin University Graduate School, Kobe, Hyogo, Japan; 2Department of Rehabilitation, Maehara Orthopedics Rehabilitation Clinic, Obu, Aichi, Japan; 3Department of Physical Therapy, Faculty of Rehabilitation, Kobe Gakuin University, Kobe, Hyogo, JapanCorrespondence: Takafumi Hattori, Faculty of Rehabilitation, Kobe Gakuin University Graduate School, 518 Arise, Ikawadani-cho, Nishi-ku, Kobe, Hyogo, 651-2180, Japan, Tel/Fax +81-78-974-2461, Email hattor91@gmail.comPurpose: Knee osteoarthritis (KOA) is a degenerative disease with inflammation, becoming persistent as it progresses, resulting in reduced quality of life. Exercise is the recommended treatment for KOA; however, the extent of pain reduction with exercise is heterogeneous and the prognostic implications of baseline factors in patients undergoing exercise are still unknown. This study examined the association between the response to exercise therapy and clinical outcomes, radiologic severity, and pain sensitization, and investigated the optimal predictive value for the effectiveness of exercise.Patients and Methods: Demographics, radiologic severity, pressure pain threshold (PPT), and temporal summation of pain (TSP) at the knee, tibia, and forearm were assessed at baseline. The pain numeric rating scale (NRS) was assessed before and after 12 weeks of exercise. Patients were divided into responder/non-responder groups according to recommended criteria: responder, ≥ 30% reduction in pain; non-responder, < 30% reduction in pain, and each variable was compared between the groups. The area under the curve (AUC) and cutoff points were determined by receiver operating characteristic curve analysis.Results: Sixty-five patients were categorized as responders and 26 as non-responders. In the non-responder group, baseline NRS (P< 0.01), pain duration (P< 0.01), and TSP at the knee (P< 0.001) and tibia (P< 0.05) were significantly higher, and PPT at the knee (P< 0.001), tibia (P< 0.001), and forearm (P< 0.001) were significantly lower, than those in the responder group; however, no significant differences between groups were found in other demographics and radiologic severity. The variables that showed moderate or better predictive ability (AUC≥ 0.7) were PPT at the knee (cutoff points: 241.5 kPa), tibia (307.5 kPa), forearm (318.5 kPa), and TSP at the knee (15.5 mm).Conclusion: Our findings suggest that pain sensitization is associated with the response to exercise therapy. Furthermore, we provide clinically predictive values for PPT and TSP in predicting the outcome to exercise in KOA.Keywords: pressure pain threshold, temporal summation of pain, cutoff point, prognostic prediction

Yuto Niwa,1 Kazuhiro Shimo,2 Satoshi Ohga,2 Yuji Tokiwa,1 Takafumi Hattori,1 Takako Matsubara1,2 1Faculty of Rehabilitation, Kobe Gakuin University Graduate School, Kobe, Japan; 2Department of Physical Therapy, Faculty of Rehabilitation, Kobe Gakuin University, Kobe, JapanCorrespondence: Yuto Niwa, Faculty of Rehabilitation, Kobe Gakuin University Graduate School, 518 Arise, Ikawadani-cho, Nishi-ku, Kobe, Hyogo, 651-2180, Japan, Tel +81-90-6587-2828, Email rm9wol04@s.kobegakuin.ac.jpPurpose: Exercise-induced hypoalgesia (EIH) is a reduction in pain sensitivity that occurs following a single bout of exercise. However, little research has compared the EIH effects of exercise at different intensities, including low intensity, in the same participant. It is unclear as to which exercise intensities demonstrate EIH more effectively. The aim of this study was to examine and compare the effect of different intensities of exercise on pain sensitivity in the same participant.Methods: We included 73 healthy young adult volunteers (35 female and 38 male) in this experimental cross-over study. Each participant completed four experimental sessions of 30 min, consisting of aerobic exercise at 30% heart rate reserve (HRR), aerobic exercise at 50% HRR, aerobic exercise at 70% HRR, and quiet rest. EIH was assessed using the pressure pain threshold (PPT) and temporal summation of pain (TSP) in the quadriceps, biceps, and trapezius.Results: Low- and moderate-intensity exercise increased the multisegmental PPT and reduced TSP (all P < 0.05). High-intensity exercise increased the multisegmental PPT (all P < 0.05), but decreased TSP in only the quadriceps and biceps (P < 0.05), not the trapezius (P = 0.13). We found no difference in relative PPT and TSP changes between exercise intensities (P > 0.05) except for relative PPT change at the quadriceps (P < 0.05).Conclusion: Our results show that not only moderate- and high-intensity exercise, but also low-intensity exercise can produce a hypoalgesic response.Keywords: exercise intensity, exercise-induced hypoalgesia, aerobic exercise, pressure pain threshold, temporal summation of pain

Yuichi Katsura,1,2 Satoshi Ohga,3 Kazuhiro Shimo,3 Takafumi Hattori,2 Tsukasa Yamada,1,2 Takako Matsubara2,3 1Department of Rehabilitation, Kishiwada Rehabilitation Hospital, Kishiwada-shi, Osaka, 596-0827, Japan; 2Faculty of Rehabilitation, Kobe Gakuin University Graduate School, Kobe, Hyogo, 651-2180, Japan; 3Faculty of Rehabilitation, Kobe Gakuin University, Kobe, Hyogo, 651-2180, JapanCorrespondence: Yuichi Katsura, Department of Rehabilitation, Kishiwada Rehabilitation Hospital, 8-10, Kanmatsu-chou, Kishiwada-shi, Osaka, 596-0827, Japan, Tel +81-72-426-7777, Fax +81-72-426-7771, Email rm9xhj04@s.kobegakuin.ac.jpPurpose: The purpose of this study was to investigate the prevalence of post-stroke complex regional pain syndrome (CRPS) and to examine the characteristics of inactivity status of the upper limb in post-stroke CRPS patients. In addition, as a sub-analysis, the association between the upper limb inactivity status and pain intensity was investigated in post-stroke CRPS patients.Patients and Methods: This cross-sectional study included 102 patients with first-ever stroke between April 2019 and February 2020. Each patient was allocated into one of two groups based on the presence or absence of CRPS. Demographic data (age, sex, stroke etiology, lesion side, and number of days since stroke onset) were collected. The following evaluations were performed in all patients: Fugl–Meyer Assessment (FMA), Action Research Arm Test (ARAT), and Motor Activity Log (MAL). The numerical rating scale (NRS) to determine pain intensity was assessed only in patients with post-stroke CRPS.Results: Nineteen and 83 patients were assigned to the post-stroke CRPS and control group, respectively. The prevalence of post-stroke CRPS was 18.6% (19/102). FMA, ARAT, and MAL scores were significantly lower in patients with post-stroke CRPS than those without it. FMA and ARAT scores were significantly correlated with NRS scores, but MAL was almost zero-scored in patients with post-stroke CRPS.Conclusion: The study results indicated that activity status of the affected upper limb was severely deteriorated, and more inactivity of the upper limb was associated with higher pain intensity in patients with post-stroke CRPS. Thus, our results suggest that post-stroke CRPS may be influenced by the degree of upper limb inactivity after stroke.Keywords: complex regional pain syndrome, post-stroke shoulder-hand syndrome, stroke, Fugl–Meyer Assessment, Action Research Arm Test, Motor Activity Log

Smoking is closely associated with the development of various cancers and tobacco-related illnesses such as cardiovascular and respiratory disorders. However, data are scarce on the relationship between smoking and both acute and chronic pain. In addition to nicotine, tobacco smoke contains more than 4000 different compounds. Although nicotine is not the sole cause of smoking-induced diseases, it plays a critical role in pain-related pathophysiology. Despite the acute analgesic effects of nicotine, long-term exposure leads to tolerance and increased pain sensitivity due to nicotinic acetylcholine receptor desensitization and neuronal plastic changes. The purpose of smoking cessation interventions in smoking patients with pain is primarily not only to reduce their pain and associated limitations in activities of daily living, but also to improve the outcomes of underlying pain-causing conditions and reduce the risks of tobacco-related disorders. This statement aims to summarize the available evidence on the impact of smoking on pain and to inform medical professionals of the significance of smoking cessation in patients with pain.