Efficacy of combined hand exercise intervention in patients with chemotherapy-induced peripheral neuropathy: a pilot randomized controlled trial.

PURPOSE: Previous evidence regarding the impact of exercise interventions on chemotherapy-induced peripheral neuropathy often focuses on lower-extremity functions, such as muscle strength and balance ability, while their effects on upper extremities remain unknown. We aimed to evaluate the efficacy of combined hand exercise intervention on upper-extremity function, symptoms, and quality-of-life in patients with chemotherapy-induced peripheral neuropathy (CIPN). METHODS: After screening 341 patients, 42 were randomly assigned to either the intervention (n = 21) or control (n = 21) group. Participants were evaluated at baseline (T0) and after one (T1) and two (T2) chemotherapy cycles. The primary outcome was upper-extremity function measured using the Michigan Hand Outcomes Questionnaire (MHQ) at T2. The intention-to-treat and as-treated populations were compared using a mixed-effect model. RESULTS: In the intention-to-treat analysis, the decline in activities of daily living of MHQ was significantly suppressed in the intervention group compared with that in the control group at T2 (difference: 7.23; 95% confidence interval: 0.35-14.10). Similarly, in the as-treated analysis, the decline in activities of daily living of MHQ was significantly suppressed in the intervention group compared with that in the control group at T2 (difference: 13.09; 95% confidence interval: 5.68-20.49). Pain also significantly improved in the intervention group compared with that in the control group at T2 (difference: 13.21; 95% confidence interval: - 22.91 to - 3.51). CONCLUSION: The combined hand exercise intervention may improve upper-extremity function, such as by suppressing decline in ADL, and reduce pain in patients with CIPN.

Effects of occupational therapy on improvements in the handwriting ability of the adult non-dominant hand: An exploratory randomised controlled trial.

INTRODUCTION: Occupational therapy often involves handwriting acquisition practices that include the non-dominant hand when improvements in the dominant hand function are not possible because of trauma or stroke. This study explored whether character tracing and using a pegboard can effectively improve the handwriting of the non-dominant hand. METHODS: A randomised controlled trial involving 60 healthy university students aged ≥18 years was conducted. Participants were randomly assigned to the writing group, peg group or control group. The character recognition rate was evaluated by computer software. Furthermore, character quality and writing speed were evaluated by humans using global legibility scales. Evaluations were performed before the intervention (baseline) and on days 5 and 10 of the intervention. Using the non-dominant hand, the writing group traced characters on paper with a ballpoint pen, and the peg group used a pegboard for 15 min/day for 10 days. RESULTS: Compared with the peg and control groups, the writing group showed significant improvements in the character recognition rate and global legibility scale score. However, the global legibility scale score did not improve to the same level as that achieved with the dominant hand. None of the evaluation scores of the peg group showed significant improvements compared with those of the control group. There were no significant differences in improvements in the writing speed of the writing and peg groups compared with the control group. CONCLUSION: Tracing characters can improve the handwriting ability of the non-dominant hand, but using a pegboard may be less effective. Future research is needed to examine how much practice is necessary to improve the handwriting ability of the non-dominant hand sufficiently.

Impact of sensory impairments on dementia incidence and symptoms among Japanese older adults.

BACKGROUND: Dementia and behavioural and psychological symptoms of dementia affect older adults' care-need levels. With aging comes an increase in the incidence of sensory impairments, which promotes the development of dementia. We investigated the association between sensory impairments - visual impairment (VI), hearing impairment (HI), and dual sensory impairment (DSI), the behavioural and psychological symptoms of dementia, and dementia incidence. METHODS: This was a retrospective study that used Japanese long-term care insurance certification data from 2010 to 2017 of City A. The 2190 older adults who did not have dementia in 2010 were classified into four impairment categories: VI, HI, DSI, and no sensory impairment. The incidence of dementia was examined using Kaplan-Meier survival analysis and log-rank testing. Cox proportional hazards analysis was used to investigate the risk of developing dementia associated with sensory impairments, compared to the risk for no sensory impairment. Pearson's χ2 tests were used to compare the prevalence of behavioural and psychological symptoms of dementia among the four groups. RESULTS: HI and DSI were associated with a higher cumulative dementia incidence compared to no sensory impairment (log-rank χ2 = 10.42; P  < 0.001, and log-rank χ2 = 39.92; P  < 0.001, respectively), and DSI showed higher cumulative dementia incidence than HI (log-rank χ2 = 11.37; P  = 0.001). Cox proportional hazards analysis showed that DSI is the greatest risk factor for developing dementia among sensory impairments (hazard ratio, 1.45; 95% CI, 1.22-1.71; P < 0.001). Older adults with VI had a significantly higher prevalence of day-night reversal than the other groups. CONCLUSIONS: Our results indicate that older adults with sensory impairments have a high incidence of dementia, with DSI presenting the greatest risk. Older adults with VI were found to be more likely to have day-night reversal symptoms when dementia occurs.

Somatosensory cortex excitability changes due to differences in instruction conditions of motor imagery.

Purpose Vivid motor imagery appears to be associated with improved motor learning efficiency. However, the practical difficulties in measuring vivid motor imagery warrant new analytical approaches. The present study aimed to determine the instruction conditions for which vividness in motor imagery could be more easily seen and the excitability of the sensory cortex as it relates to the motor image. Materials and methods In total, 15 healthy, right-handed volunteers were instructed to imagine grasping a rubber ball under a verbal-only instruction condition (verbal condition), a verbal + visual instruction condition (visual condition), and a verbal + execution (physically grasping a real ball) condition (execution condition). We analyzed motor imagery-related changes in somatosensory cortical excitability by comparing somatosensory-evoked potentials in each condition with the rest (control) condition. We also used a visual analogue scale to measure subject-reported vividness of imagery. Results We found the N33 component was significantly lower in the execution condition than in the rest condition (p < 0.05). The results suggested a gating effect via central efferent mechanisms that affected the excitability of areas 3b or 1 in the primary somatosensory cortex, but only in the execution condition. Conclusions These data suggest that experiencing a movement through actual motor execution immediately prior to performing mental imagery of that movement enhances the excitability of motor-related cortical areas. It is suggested that the excitability of the motor-related region increased as a result of the motor imagery in the execution condition acting on the corresponding somatosensory cortex.

Effect of mental practice using inverse video of the unaffected upper limb in a subject with chronic hemiparesis after stroke.

[Purpose] The aim of this case study was to investigate whether a method of mental practice (MP) using an inverse video of a subject's unaffected limb to complement the vividness of motor imagery (MI) would be effective for improving affected upper limb function. [Subjects and Methods] The participant was 60-year-old male in the chronic stage of stroke recovery with left sided hemiparesis. The design of the study was AB method of Single-System-Design. He performed the MP as a home program with DVD. The intervention lasted 30 minutes a session, twice a day, 5 times a week, over 6 weeks. The DVD was created using inverse video of his unaffected upper limb. Primary outcome measures were used the Fugl-Meyer Assessment for upper limb (FMA) and the Motor Activity Log (MAL) 3 times each baseline, intervention and follow-up. The subjective vividness of MI was assessed by the Visual Analog Scale (VAS). [Results] FMA and MAL score during intervention was improved significantly comparing to baseline, and maintained in withdrawal. VAS score was improved in withdrawal comparing to baseline. [Conclusion] Results suggested that effect of mental practice for stroke patients increased by vividness of motor imagery was improved by the inverse video.

Does Dialysis Therapy Cause Cognitive Impairment in Older Adults? A Propensity Score Matching Retrospective Study From a Japanese Long-Term Care Insurance Certification Survey.

This study explores the longitudinal connection between dialysis therapy in older adults and the incidence of cognitive impairment, and trends of general abilities. We conducted a retrospective propensity score matching (PSM) analysis of data from the care-needs certification survey in City A, Japan, spanning 2017 to 2021. Our sample comprised 11 443 initially cognitively intact older adults from the baseline year 2017. Among them, individuals had received dialysis therapy at baseline, and 216 individuals were included after PSM. The dialysis group had a significantly lower incidence of cognitive impairment during follow-up than the control group (P = 0.02). The competing risk of death was significantly higher in the dialysis group than in the control group (P < .001). Both groups showed a decline in their comprehensive ability over the time. There have been several reports of a negative association between dialysis and cognitive impairment, but more detailed investigation of the longitudinal relationship may be needed. Comprehensive support remains critical for both dialysis and non-dialysis older adults.

Relationship between Corticospinal Excitability While Gazing at the Mirror and Motor Imagery Ability.

Mirror therapy (MT) helps stroke survivors recover motor function. Previous studies have reported that an individual's motor imagery ability is related to the areas of brain activity during motor imagery and the effectiveness of motor imagery training. However, the relationship between MT and motor imagery ability and between corticospinal tract excitability during mirror gazing, an important component of MT, and motor imagery ability is unclear. This study determined whether the motor-evoked potential (MEP) amplitude while gazing at the mirror relates to participants' motor imagery abilities. Twenty-four healthy right-handed adults (seven males) were recruited. Transcranial magnetic stimulation was performed while gazing at the mirror, and MEP of the first dorsal interosseous muscle of the right hand were measured. Motor imagery ability was measured using the Kinesthetic and Visual Imagery Questionnaire (KVIQ), which assesses the vividness of motor imagery ability. Additionally, a mental chronometry (MC) task was used to assess time aspects. The results showed a significant moderate correlation between changes in MEP amplitude values while gazing at the mirror, as compared with resting conditions, and assessment scores of KVIQ. This study shows that corticospinal excitability because of mirror gazing may be related to the vividness of motor imagery ability.

Risk factors for nursing home admission among older adults: Analysis of basic movements and activities of daily living.

This retrospective study aimed to clarify the risk of older adults' nursing home placement in terms of basic movements and activities of daily living (ADLs) by analyzing data from a long-term care insurance certification survey in 2016‒2018 in City A. Of the 21,520 people certified as needing care, 16,865 could be followed up until 2018. Data on sex, age, household structure, and level of care required were obtained. Those who lived at home and at nursing homes were categorized as the "Unchanged group" and the "Changed group," respectively. Multivariate binomial logistic regression analysis was performed, with group type as the dependent variable and basic movement and ADL scores as the independent variables. For factor analysis according to care level, participants were classified into support need levels 1 and 2, care need levels 1 and 2, and care need levels 3, 4, and 5. For those categorized into support need levels 1 and 2, standing on one leg and transferring (basic movements) and urination and face cleaning (ADLs) were associated with nursing home placement. For those in care need levels 1 and 2, getting up and transferring (basic movements) and bathing, urination, face cleaning, and hair styling (ADL) were significantly associated with nursing home placement. For those in care need levels 3, 4, and 5, sitting and transferring (basic movements) and self-feeding and defecation (ADL) were significant. Occupational therapists must focus on older adults' declining ADLs and basic movements and relay the necessary information to patients, families, and other healthcare professionals to ensure appropriate and prompt care delivery.

Difference between the Effects of Peripheral Sensory Nerve Electrical Stimulation on the Excitability of the Primary Motor Cortex: Examination of the Combinations of Stimulus Frequency and Duration.

Peripheral sensory nerve electrical stimulation (PES) excites the primary motor cortex and is expected to improve motor dysfunction post-stroke. However, previous studies have reported a variety of stimulus frequencies and stimulus duration settings, and the effects of these different combinations on primary motor cortex excitability are not clear. We aimed to clarify the effects of different combinations of stimulus frequency and stimulus duration of PES on the excitation of primary motor cortex. Twenty-one healthy individuals (aged > 18 years, right-handed, and without a history of neurological or orthopedic disorders) were included. Each participant experienced three different stimulation frequencies (1, 10 and 50 Hz) and durations (20, 40 and 60 min). Motor-evoked potentials (MEPs) were recorded pre- and post-PES. The outcome measure was the change in primary motor cortex excitability using the MEP ratio. We used a D-optimal design of experiments and response surface analysis to define the optimal combination within nine different settings inducing more satisfying responses. The combination of stimulation frequency and stimulation time that maximized the desirability value was 10 Hz and 40 min, respectively. The results of this study may provide fundamental data for more minimally invasive and effective implementation of PES in patients with stroke.

[Differences in the bone mineral density in patients with Kanemi Yusho treated before and after the age of 18 years].

This study examined patients with Kanemi Yusho. The patients' height, weight, and bone mineral density were measured. The density of the distal end of the radius was measured using dual energy X-ray absorptiometry and the calcaneum was measured with ultrasound. We also measured urine levels of cross-linked N-telopeptides of type I collagen, serum tartrate-resistant acid phosphatase 5b, serum bone-specific alkaline phosphatase, serum Ca, serum P and blood PCB level. The patient group that took PCBs when they were 0 to 18 years old (such patients were 42 to 60 years old at the time of the study) showed no correlation between the bone density of the radius and calcaneum in spite of treatment received when they were over 18 years of age (> 60 years of age at the time of the study). The bone mineral density in Kanemi Yusho was not different from the control group. The levels of only serum bone-specific alkaline phosphatase were correlated with the bone mineral density of the radius and calcaneum in patients treated when they were over 18 years of age (currently over 60 years old). PCBs might have had an effect on bone density and bone metabolism.

Causes of changes in basic activities of daily living in older adults with long-term care needs.

OBJECTIVE: To elucidate basic activities of daily living (BADL) changes, and the causes, in older adults with long-term care needs. METHODS: This retrospective study utilised long-term care insurance (LTCI) certification survey data from 2010 to 2017 in City A. RESULTS: In decreasing likelihood of requiring assistance, BADL items were grooming, bathing, getting dressed/undressed, mobility, toilet hygiene, functional mobility and self-feeding. Cox proportional hazard regression indicated that age correlated with need for assistance for all BADL items. Male sex corresponded to needing assistance with BADL items other than grooming and functional mobility. Shared living corresponded to needing assistance with BADL items other than grooming and bathing. Visual acuity corresponded to needing assistance with grooming. CONCLUSION: The most significant result was using survival curves to visualise the changes in BADL items of older adults with LTCI. These findings could help develop rehabilitation programs to prevent the need for BADL assistance in older adults.

Long-Term Changes in Older Adults' Independence Levels for Performing Activities of Daily Living in Care Settings: A Nine-Year Follow-Up Study.

This study aimed to clarify the variability in the independence profiles of specific activities of daily living (ADL) among older men and women. The research subjects were 5872 older adults (1143 men and 4729 women) certified as requiring nursing care or support (based on data obtained from the nursing care insurance certification survey database) who could be surveyed in both 2009 and 2018. Using item response theory, this study compared longitudinal data of difficulties faced by older adults during ADL. The results indicated that among the long-term care insurance-certified persons, in 2009, men had higher ADL difficulty than women in all ADL items, and in 2018, there was no significant difference in items other than dressing and excretion. Furthermore, the difference in the rate of ADL difficulty level over 9 years was significantly higher in women than in men. It was shown that the progression of ADL disability due to aging is faster in men on a yearly basis, but it increases in women with aging. Therefore, it was suggested that the rate of ADL difficulty varies depending on age and sex.

Cerebral Hemodynamics During a Cognitive-Motor Task Using the Limbs.

Background: Antagonistic tasks are cognitive-motor task trainings. Intervention programs involving antagonistic exercise tasks are being employed to help prevent falls and reduce the need for nursing care in older populations. Meanwhile, the effects of such tasks on blood flow in the brain remain obscure. This study aimed to clarify the effects of antagonistic tasks on prefrontal cortical cerebral hemodynamics. Materials and Methods: We assessed 13 healthy adults (two men, 11 women; mean age, 21.4 ± 1.0 years). Participants imitated each of the antagonistic tasks presented on a PC monitor placed at a 120-mm viewing distance. All participants performed six tasks, consisting of upper-limb tasks (non-antagonism, simple antagonism, and complex antagonism) and upper- and lower-limb tasks (tasks combining lower-limb opening and closing movements with each upper-limb task). We used near-infrared spectroscopy (NIRS) to measure cerebral blood flow dynamics, with oxygenated hemoglobin (Oxy-Hb) concentration changes as the main outcome. A 10-channel probe was placed on the participants' forehead, focusing on the prefrontal cortex. We first obtained a baseline NIRS measurement for 10 s; the participants then imitated the task presented on the PC monitor for 90 s. We measured the number of errors and the subjective difficulty of each task. Results: The increase in prefrontal cortex Oxy-Hb concentration was significantly higher in the complex antagonist conditions than in the non-antagonistic and simple antagonistic conditions. There were no significant prefrontal cortex Oxy-Hb differences between the upper limb and upper- and lower-limb conditions (increasing number of motor limbs). Conclusions: The study findings support that an increase in finger-shaped complexity has a greater effect on cerebral blood flow dynamics in the prefrontal cortex than does an increase in the number of motor limbs involved in the task.

Relationship Between Attention Bias and Psychological Index in Individuals With Chronic Low Back Pain: A Preliminary Event-Related Potential Study.

Introduction: Attention bias towards pain-related information exists in patients with chronic pain, and recently, attention bias modification (ABM) training has been administered to patients with chronic pain. In this study, we conducted an attention bias modification task in conjunction with event-related potential measurements for individuals with chronic low back pain (LBP) and investigated the relationship between attention bias and psychological assessment. Methods: Eleven women and two men with chronic LBP participated in the study. Results: The Japanese version of the STarT Back Screening Tool (J-SBST) total score was significantly correlated with the N1 amplitude of Cz. The J-SBST psychological score was significantly correlated with the N1 amplitude of Cz and with reaction time (RT). The Japanese version of the Pain Catastrophizing Scale (PCS) and Japanese version of the Beck Depression Inventory-Second Edition (BDI-II) scores were significantly correlated with the P2 amplitude at Fz (only PCS), Cz, and Pz. Conclusions: Our findings suggest that J-SBST, which provides a comprehensive evaluation of psychological factors, PCN with measuring of catastrophizing in the context of actual or anticipated pain, and BDI-II, can likely help identify chronic LBP patients with attention bias. For chronic LBP patients who are classified according to J-SBST or PCN pain-related outcome improvement with ABM training can be expected.

Impact of Outpatient Rehabilitation Service in Preventing the Deterioration of the Care-Needs Level Among Japanese Older Adults Availing Long-Term Care Insurance: A Propensity Score Matched Retrospective Study.

Outpatient rehabilitation (OR) and outpatient day long-term care (ODLC) services are frequently used by older adult patients in Japan. However, there is a need to clarify that OR service, which has more rehabilitation professionals than ODLC, has the role of providing rehabilitation. This retrospective study examined the impact of OR services by comparing the two services based on City A data from the care-needs certification survey conducted between 2015 to 2017. We performed a propensity score matched analysis to compare the changes in the care level and function of OR and ODLC users after two years. The results showed that OR users showed a lower deterioration in care levels and less decline in the activities of daily living (ADL) in dementia and adaptation to social life. In the analysis of older adults requiring support, OR users had a lower deterioration in care levels and less decline in the ADL in dementia and behavioral and psychological symptoms than ODLC users did. There was no difference between the two services with respect to older adults requiring long-term care. The OR service has had an increasingly preventive effect on the deterioration of care levels compared to the ODLC service, which was particularly evident in older adults requiring support.

Effect of occupation-based interventions in patients with haematopoietic malignancies undergoing chemotherapy: A pilot randomised controlled trial.

BACKGROUND/OBJECTIVE: Chemotherapy for cancer negatively affects activities of daily living and quality of life. This study aimed to validate and compare the efficacy of two different interventions in patients with haematopoietic malignancies undergoing chemotherapy: (1) occupation-based interventions, designed using the Aid for Decision-making in Occupation Choice (ADOC) (an iPAD application) and (2) impairment-based interventions. ADOC helps promote decision-making during activities and participation in occupation-based goal setting. The impairment-based intervention group served as the comparison group and underwent impairment-based interventions focusing on dysfunction. METHODS: In this single-blinded pilot randomised controlled trial, 19 participants received an occupation-based intervention (n = 9) or an impairment-based intervention (n = 10). The treatment period comprised two sessions. Recruitment, compliance and outcome completion rates were calculated for the study. Effect sizes were examined for outcomes regarding physical performance, instrumental activities of daily living and quality of life as evaluated by a blinded assessor. RESULTS: In this study, 24.8% (28/113) of the eligible patients with haematopoietic malignancies were enrolled, and 67.9% (19/28) of these were retained up to the post-assessment stage. Recruitment (25%) and compliance (68%) rates were satisfactory. The Functional Assessment of Cancer Therapy-General emotional well-being and total scores were significantly higher for the occupation-based intervention group than for the impairment-based intervention group (both p < 0.05; d = 0.54, d = 0.51, respectively). Other outcomes showed no significant differences. CONCLUSION: Occupation-based interventions designed using the ADOC application were useful for patients with haematopoietic malignancies.

Actual use of and satisfaction associated with rollators and "shopping carts" among frail elderly Japanese people using day-service facilities.

Purpose This study aimed at clarifying the actual use of and satisfaction with rollators and "shopping carts" (wheeled walkers with storage) among frail elderly people, who were certified by a long-term care insurance system as users of facilities that provide day-service nursing care and rehabilitation. Methods We identified 1247 frail elderly people who used day-service facilities, and evaluated their actual use of, and satisfaction with, rollators and shopping carts. Results Forty-four (3.5%) individuals used rollators, and 53 (4.3%) used shopping carts. The shopping cart group contained more individuals who were certified as care level 1 (26.4%), than the rollator group (20.5%), and 52.8% of the shopping cart group was certified as care levels 1-3. The scores for "repairs and services" and "follow-up" from the Quebec User Evaluation of Satisfaction with assistive Technology second version (QUEST 2.0) survey were significantly higher in the rollator group than in the shopping cart group. Conclusions The QUEST 2.0 scores revealed that shopping cart users exhibit insufficient "repairs and services" and "follow-up" scores. As frail elderly people with poor care status accounted for >50% of the shopping cart group, these individuals urgently need walking aids that are tailored to their care status. Implications for Rehabilitation We conclude that walking aid fitting must be tailored to each persons care status, and suggest that a system should be established to allow occupational or physical therapists to provide this fitting Moreover, our analysis of the QUEST2.0 service scores revealed that repairs, services, and follow-up are insufficient to meet the needs of shopping cart users.

Changes in Cerebral Hemodynamics during Complex Motor Learning by Character Entry into Touch-Screen Terminals.

INTRODUCTION: Studies of cerebral hemodynamics during motor learning have mostly focused on neurorehabilitation interventions and their effectiveness. However, only a few imaging studies of motor learning and the underlying complex cognitive processes have been performed. METHODS: We measured cerebral hemodynamics using near-infrared spectroscopy (NIRS) in relation to acquisition patterns of motor skills in healthy subjects using character entry into a touch-screen terminal. Twenty healthy, right-handed subjects who had no previous experience with character entry using a touch-screen terminal participated in this study. They were asked to enter the characters of a randomly formed Japanese syllabary into the touch-screen terminal. All subjects performed the task with their right thumb for 15 s alternating with 25 s of rest for 30 repetitions. Performance was calculated by subtracting the number of incorrect answers from the number of correct answers, and gains in motor skills were evaluated according to the changes in performance across cycles. Behavioral and oxygenated hemoglobin concentration changes across task cycles were analyzed using Spearman's rank correlations. RESULTS: Performance correlated positively with task cycle, thus confirming motor learning. Hemodynamic activation over the left sensorimotor cortex (SMC) showed a positive correlation with task cycle, whereas activations over the right prefrontal cortex (PFC) and supplementary motor area (SMA) showed negative correlations. CONCLUSIONS: We suggest that increases in finger momentum with motor learning are reflected in the activity of the left SMC. We further speculate that the right PFC and SMA were activated during the early phases of motor learning, and that this activity was attenuated with learning progress.

Monitoring Local Regional Hemodynamic Signal Changes during Motor Execution and Motor Imagery Using Near-Infrared Spectroscopy.

The aim of this study was to clarify the topographical localization of motor-related regional hemodynamic signal changes during motor execution (ME) and motor imagery (MI) by using near-infrared spectroscopy (NIRS), as this technique is more clinically expedient than established methods (e.g., fMRI). Twenty right-handed healthy subjects participated in this study. The experimental protocol was a blocked design consisting of 3 cycles of 20 s of task performance and 30 s of rest. The tapping sequence task was performed with their fingers under 4 conditions: ME and MI with the right or left hand. Hemodynamic brain activity was measured with NIRS to monitor changes in oxygenated hemoglobin (oxy-Hb) concentration. Oxy-Hb in the somatosensory motor cortex (SMC) increased significantly only during contralateral ME and showed a significant interaction between task and hand. There was a main effect of hand in the left SMC. Although there were no significant main effects or interactions in the supplemental motor area (SMA) and premotor area (PMA), oxy-Hb increased substantially under all conditions. These results clarified the topographical localization by motor-related regional hemodynamic signal changes during ME and MI by using NIRS.

Excitability of the primary motor cortex increases more strongly with slow- than with normal-speed presentation of actions.

INTRODUCTION: The aim of the present study was to investigate how the speed of observed action affects the excitability of the primary motor cortex (M1), as assessed by the size of motor evoked potentials (MEPs) induced by transcranial magnetic stimulation (TMS). METHODS: Eighteen healthy subjects watched a video clip of a person catching a ball, played at three different speeds (normal-, half-, and quarter-speed). MEPs were induced by TMS when the model's hand had opened to the widest extent just before catching the ball ("open") and when the model had just caught the ball ("catch"). These two events were locked to specific frames of the video clip ("phases"), rather than occurring at specific absolute times, so that they could easily be compared across different speeds. MEPs were recorded from the thenar (TH) and abductor digiti minimi (ADM) muscles of the right hand. RESULTS: The MEP amplitudes were higher when the subjects watched the video clip at low speed than when they watched the clip at normal speed. A repeated-measures ANOVA, with the factor VIDEO-SPEED, showed significant main effects. Bonferroni's post hoc test showed that the following MEP amplitude differences were significant: TH, normal vs. quarter; ADM, normal vs. half; and ADM, normal vs. quarter. Paired t-tests showed that the significant MEP amplitude differences between TMS phases under each speed condition were TH, "catch" higher than "open" at quarter speed; ADM, "catch" higher than "open" at half speed. CONCLUSIONS: These results indicate that the excitability of M1 was higher when the observed action was played at low speed. Our findings suggest that the action observation system became more active when the subjects observed the video clip at low speed, because the subjects could then recognize the elements of action and intention in others.