Over recent decades, wearable inertial sensors have become popular means to quantify physical activity and mobility. However, research assessing measurement accuracy and precision is required, especially before using device-based measures as outcomes in trials. The GT9X Link is a recent activity monitor available from ActiGraph, recognized as a “gold standard” and previously used as a criterion measure to assess the validity of various consumer-based activity monitors. However, the validity of the ActiGraph GT9X Link is not fully elucidated. A systematic review was undertaken to synthesize the current evidence for the criterion validity of the ActiGraph GT9X Link in measuring steps and energy expenditure. This review followed the PRISMA guidelines and eight studies were included with a combined sample size of 558 participants. We found that (1) the ActiGraph GT9X Link generally underestimates steps; (2) the validity and accuracy of the device in measuring steps seem to be influenced by gait speed, device placement, filtering process, and monitoring conditions; and (3) there is a lack of evidence regarding the accuracy of step counting in free-living conditions and regarding energy expenditure estimation. Given the limited number of included studies and their heterogeneity, the present review emphasizes the need for further validation studies of the ActiGraph GT9X Link in various populations and in both controlled and free-living settings.

Backward walking often occurs in everyday life. It is more complex than forward walking and is associated with decreased coordination. However, it is unclear if a reduced backward walking performance is associated with impaired cognition. This could be particularly relevant as gait and cognitive deficits commonly occur in Parkinson’s disease. The objective of this systematic review was to synthesize the evidence on the association between backward walking and cognition in persons with Parkinson’s disease. The electronic databases PubMed and Web of Science were systematically searched, and the quality of eligible studies was assessed. Two studies met the inclusion criteria, but study protocols, investigated population, and outcome measures differed substantially. One study showed lower backward walking speed in patients with Parkinson’s disease with poorer attention test performances. The second study showed a weak correlation between executive cognitive functions and backward walking speed. Given the low number of studies, the heterogenous study design, and the inconsistent results, the present review highlights the need to further investigate the association between backward walking and cognition in patients with Parkinson’s disease.

Introduction: Parkinson’s disease (PD) is a neurodegenerative disease characterized by motor symptoms and gait impairments. Among them, freezing of gait (FOG) is one of the most disabling manifestations. Backward walking (BW) is an activity of daily life that individuals with PD might find difficult and could cause falls. Recent studies have reported that gait impairments in PD were more pronounced in BW, particularly in people presenting FOG. However, to the best of our knowledge, no systematic review has synthetized the literature which compared BW performance in PD patients with and without FOG. Objective: The aim of this study was to evaluate the differences in BW performance between PD patients with FOG and PD patients without FOG. Methods: Two databases, PubMed and Web of Science, were systematically searched to identify studies comparing BW performance in PD patients with and without FOG. The National Institutes of Health (NIH) tool was used to assess the quality of the studies included. Results: Seven studies with 431 PD patients (179 PD with FOG and 252 PD without FOG) met the inclusion criteria and were included in this review. Among them, 5 studies reported walking speed, 3 studies step length, stride length and lower limb range of motion, 2 studies functional ambulation profile, toe clearance height, swing, and stance percent and 1 study reported the decomposition index and stepping coordination. Compared to PD patients without FOG, PD patients with FOG showed slower walking speed and reduced step length in 3 studies, shorter stride length, lower functional ambulation profile and decreased ankle range of motion in 2 studies, and smaller swing percent, higher stance percent, worse stepping coordination, greater decomposition between movements, and lower toe clearance height in one study. Conclusion: Despite the small number of included studies, the findings of this review suggested that PD patients with FOG have worse gait performance during the BW task than PD without FOG.

Background: People with Parkinson’s disease (PwPD) often experience sleep disturbances and reduced physical activity. Altered sleep behavior and lower daily steps have been linked to disease severity and symptom burden. Although physical activity may influence sleep, few studies have examined the relationship between sleep parameters and daily steps in PD. This scoping review aimed to review current knowledge on sleep parameters and daily steps collected concurrently in PwPD and their potential association. Methods: A systematic search was conducted in five databases, PubMed, Web of Science, Sport Discus, Cochrane Library, and Scopus. Methodological quality was assessed using a customized quality checklist developed by Zanardi and collaborators for observational studies, based on Downs and Black’s work. Results: Out of 1421 records, five studies met the eligibility criteria and were included in the review. Four studies reported wearable-based measurements of both step count and sleep parameters, while one study reported wearable-based measurements of step count and self-reported sleep measures. Two studies examined the association between sleep parameters and step count. One study did not find any correlation between sleep and step count, whereas one study reported a positive correlation between daytime sleepiness and step count. Conclusions: This review highlighted the lack of research investigating the relationship between sleep parameters and step count as an indicator of physical activity in PwPD. Findings are inconsistent with a potential positive correlation emerging between daytime sleepiness and step count. Findings also pointed toward lower step count and reduced sleep duration in PwPD, as measured with wearable devices.

Background/Objectives: Freezing of gait (FOG) and sleep disturbances are common in people with Parkinson’s disease (PwPD). A bidirectional association between them has been suggested, but quantitative evaluations are scarce. This study aimed to compare sleep disturbances in mild-to-moderate PwPD with (PD+FOG) and without FOG (PD−FOG), and to assess the association between FOG severity and sleep parameters. Methods: Data from 54 PwPD with disease stage <4 and no severe cognitive decline were included (27 PD+FOG and 27 propensity score-matched for age, sex, and disease duration PD−FOG). Demographics and clinical variables were collected. Clinical assessment included the new freezing of gait questionnaire (NFOG-Q), Parkinson’s Disease Sleep Scale (PDSS-2), Epworth Sleepiness Scale (ESS) and Movement Disorder Society Unified Parkinson’s Disease Rating Scale (MDS-UPDRS). Mann–Whitney U, Fisher’s exact and Spearman’s tests were used for group comparisons and correlations, respectively. Results: Significant differences were observed between PD+FOG and PD−FOG groups in MDS-UPDRS part II (p = 0.011) and part IV (p = 0.011), with higher scores in PD+FOG participants. No significant differences were found in PDSS-2 or ESS between the two groups. A significant moderate positive correlation was found between NFOG-Q score and PDSS-2 (ρ = 0.416; p = 0.044) in PD+FOG participants. Conclusions: FOG severity was positively associated with sleep disturbances within the PD+FOG group. However, no significant difference in sleep quality or excessive daytime sleepiness was found between PD+FOG and PD−FOG after propensity score matching. PD+FOG participants experienced more severe motor complications and greater impairment in daily activities compared to PD−FOG.

Parkinson’s disease (PD) is characterized by motor and non-motor symptoms that impair quality of life (QoL). Pharmacological treatments have side effects; therefore, non-pharmacological interventions, including Nordic walking (NW), are recommended to complement treatment and improve symptoms and QoL. However, previous systematic reviews on the effects of NW in PD reported methodological inconsistencies and evidence gaps, and no bibliometric analysis has examined research trends in this field. This study aimed to update and synthesize the effects of NW on motor and non-motor outcomes and QoL in PD, and to provide a bibliometric overview of research trends. A systematic search of PubMed, Web of Science, Cochrane, SPORTDiscus, and Scopus was conducted up to March 2025. Twenty-one studies (14 RCTs) were included. NW interventions improved motor symptoms, functional mobility, walking capacity, balance, QoL, and non-motor symptoms such as depression, cognition, and fatigue. Meta-analyses confirmed clinically meaningful improvements in MDS-UPDRS III scores and 6-minute walk test performance. However, NW was not consistently superior to other active interventions. Bibliometric analysis revealed a declining publication trend since 2020 and limited international collaborations. Overall, NW appears to be a beneficial supervised exercise option for ambulatory people with PD, although heterogeneity and limited data preclude firm conclusions.