Longitudinal associations of diurnal rest-activity rhythms with fatigue, insomnia, and health-related quality of life in survivors of colorectal cancer up to 5 years post-treatment.

BACKGROUND: There is a growing population of survivors of colorectal cancer (CRC). Fatigue and insomnia are common symptoms after CRC, negatively influencing health-related quality of life (HRQoL). Besides increasing physical activity and decreasing sedentary behavior, the timing and patterns of physical activity and rest over the 24-h day (i.e. diurnal rest-activity rhythms) could also play a role in alleviating these symptoms and improving HRQoL. We investigated longitudinal associations of the diurnal rest-activity rhythm (RAR) with fatigue, insomnia, and HRQoL in survivors of CRC. METHODS: In a prospective cohort study among survivors of stage I-III CRC, 5 repeated measurements were performed from 6 weeks up to 5 years post-treatment. Parameters of RAR, including mesor, amplitude, acrophase, circadian quotient, dichotomy index, and 24-h autocorrelation coefficient, were assessed by a custom MATLAB program using data from tri-axial accelerometers worn on the upper thigh for 7 consecutive days. Fatigue, insomnia, and HRQoL were measured by validated questionnaires. Confounder-adjusted linear mixed models were applied to analyze longitudinal associations of RAR with fatigue, insomnia, and HRQoL from 6 weeks until 5 years post-treatment. Additionally, intra-individual and inter-individual associations over time were separated. RESULTS: Data were available from 289 survivors of CRC. All RAR parameters except for 24-h autocorrelation increased from 6 weeks to 6 months post-treatment, after which they remained relatively stable. A higher mesor, amplitude, circadian quotient, dichotomy index, and 24-h autocorrelation were statistically significantly associated with less fatigue and better HRQoL over time. A higher amplitude and circadian quotient were associated with lower insomnia. Most of these associations appeared driven by both within-person changes over time and between-person differences in RAR parameters. No significant associations were observed for acrophase. CONCLUSIONS: In the first five years after CRC treatment, adhering to a generally more active (mesor) and consistent (24-h autocorrelation) RAR, with a pronounced peak activity (amplitude) and a marked difference between daytime and nighttime activity (dichotomy index) was found to be associated with lower fatigue, lower insomnia, and a better HRQoL. Future intervention studies are needed to investigate if restoring RAR among survivors of CRC could help to alleviate symptoms of fatigue and insomnia while enhancing their HRQoL. TRIAL REGISTRATION: EnCoRe study NL6904 ( https://www.onderzoekmetmensen.nl/ ).

Functional electrical stimulation during walking in children with unilateral spastic cerebral palsy: A randomized cross-over trial.

AIM: To study if functional electrical stimulation (FES) of the peroneal nerve, which activates dorsiflexion, can improve body functions, activities, and participation and could be an effective alternative treatment in individuals with unilateral spastic cerebral palsy (CP). METHOD: A randomized cross-over trial was performed in 25 children with unilateral spastic CP (classified in Gross Motor Function Classification System levels I and II) aged 4 to 18 years (median age at inclusion 9 years 8 months, interquartile range = 7 years-13 years 8 months), 15 patients were male. The study consisted of two 12-week blocks of treatment, that is, conventional treatment (ankle foot orthosis [AFO] or adapted shoes) and FES, separated by a 6-week washout period. Outcome measures included the Goal Attainment Scale (GAS), the Cerebral Palsy Quality of Life questionnaire, and a three-dimensional gait analysis. RESULTS: Eighteen patients completed the trial. The proportion of GAS goals achieved was not significantly higher in the FES versus the conventional treatment phase (goal 1 p = 0.065; goal 2 p = 1.00). When walking while stimulated with FES, ankle dorsiflexion during mid-swing decreased over time (p = 0.006, average decrease of 4.8° with FES), with a preserved increased ankle range of motion compared to conventional treatment (p < 0.001, mean range of motion with FES +10.1° compared to AFO). No changes were found in the standard physical examination or regarding satisfaction with orthoses and feelings about the ability to dress yourself. In four patients, FES therapy failed; in 12 patients FES therapy continued after the trial. INTERPRETATION: FES is not significantly worse than AFO; however, patient selection is critical, and a testing period and thorough follow-up are needed.

Changes in running economy and running technique following 6 months of running with and without wearable-based real-time feedback.

BACKGROUND: An increasing number of commercially available wearables provide real-time feedback on running biomechanics with the aim to reduce injury risk or improve performance. OBJECTIVE: Investigate whether real-time feedback by wearable insoles (ARION) alters running biomechanics and improves running economy more as compared to unsupervised running training. We also explored the correlation between changes in running biomechanics and running economy. METHODS: Forty recreational runners were randomized to an intervention and control group and performed ~6 months of in-field training with or without wearable-based real-time feedback on running technique and speed. Running economy and running biomechanics were measured in lab conditions without feedback pre and post intervention at four speeds. RESULTS: Twenty-two individuals (13 control, 9 intervention) completed both tests. Both groups significantly reduced their energetic cost by an average of -6.1% and -7.7% for the control and intervention groups, respectively. The reduction in energy cost did not significantly differ between groups overall (-0.07 ± 0.14 J∙kg∙m-1 , -1.5%, p = 0.63). There were significant changes in spatiotemporal metrics, but their magnitude was minor and did not differ between the groups. There were no significant changes in running kinematics within or between groups. However, alterations in running biomechanics beyond typical session-to-session variation were observed during some in-field sessions for individuals that received real-time feedback. CONCLUSION: Alterations in running biomechanics as observed during some in-field sessions for individuals receiving wearable-based real-time feedback did not result in significant differences in running economy or running biomechanics when measured in controlled lab conditions without feedback.

Per-step and cumulative load at three common running injury locations: The effect of speed, surface gradient, and cadence.

Understanding how loading and damage on common running injury locations changes across speeds, surface gradients, and step frequencies may inform training programs and help guide progression/rehabilitation after injuries. However, research investigating tissue loading and damage in running is limited and fragmented across different studies, thereby impairing comparison between conditions and injury locations. This study examined per-step peak load and impulse, cumulative impulse, and cumulative weighted impulse (hereafter referred to as cumulative damage) on three common injury locations (patellofemoral joint, tibia, and Achilles tendon) across different speeds, surface gradients, and cadences. We also explored how cumulative damage in the different tissues changed across conditions relative to each other. Nineteen runners ran at five speeds (2.78, 3.0, 3.33, 4.0, 5.0 m s-1 ), and four gradients (-6, -3, +3, +6°), and three cadences (preferred, ±10 steps min-1 ) each at one speed. Patellofemoral, tibial, and Achilles tendon loading and damage were estimated from kinematic and kinetic data and compared between conditions using a linear mixed model. Increases in running speed increased patellofemoral cumulative damage, with nonsignificant increases for the tibia and Achilles tendon. Increases in cadence reduced damage to all tissues. Uphill running increased tibial and Achilles tendon, but decreased patellofemoral damage, while downhill running showed the reverse pattern. Per-step and cumulative loading, and cumulative loading and cumulative damage indices diverged across conditions. Moreover, changes in running speed, surface gradient, and step frequency lead to disproportional changes in relative cumulative damage on different structures. Methodological and practical implications for researchers and practitioners are discussed.

Differences in running technique between runners with better and poorer running economy and lower and higher milage: An artificial neural network approach.

BACKGROUND: Prior studies investigated selected discrete sagittal-plane outcomes (e.g., peak knee flexion) in relation to running economy, hereby discarding the potential relevance of running technique parameters during noninvestigated phases of the gait cycle and in other movement planes. PURPOSE: Investigate which components of running technique distinguish groups of runners with better and poorer economy and higher and lower weekly running distance using an artificial neural network (ANN) approach with layer-wise relevance propagation. METHODS: Forty-one participants (22 males and 19 females) ran at 2.78 m∙s-1 while three-dimensional kinematics and gas exchange data were collected. Two groups were created that differed in running economy or weekly training distance. The three-dimensional kinematic data were used as input to an ANN to predict group allocations. Layer-wise relevance propagation was used to determine the relevance of three-dimensional kinematics for group classification. RESULTS: The ANN classified runners in the correct economy or distance group with accuracies of up to 62% and 71%, respectively. Knee, hip, and ankle flexion were most relevant to both classifications. Runners with poorer running economy showed higher knee flexion during swing, more hip flexion during early stance, and more ankle extension after toe-off. Runners with higher running distance showed less trunk rotation during swing. CONCLUSION: The ANN accuracy was moderate when predicting whether runners had better, or poorer running economy, or had a higher or lower weekly training distance based on their running technique. The kinematic components that contributed the most to the classification may nevertheless inform future research and training.

Gait and Falls in Benign Paroxysmal Positional Vertigo: A Systematic Review and Meta-analysis.

BACKGROUND AND PURPOSE: Benign paroxysmal positional vertigo (BPPV) is one of the most common vestibular disorders, and is treated effectively with particle repositioning maneuvers (PRM). The aim of this study was to assess the influence of BPPV and treatment effects of PRM on gait, falls, and fear of falling. METHODS: Three databases and the reference lists of included articles were systematically searched for studies comparing gait and/or falls between (1) people with BPPV (pwBPPV) and controls and (2) pre- and posttreatment with PRM. The Joanna Briggs Institute critical appraisal tools were used to assess risk of bias. RESULTS: Twenty of the 25 included studies were suitable for meta-analysis. Quality assessment resulted in 2 studies with high risk of bias, 13 with moderate risk, and 10 with low risk. PwBPPV walked slower and demonstrated more sway during tandem walking compared with controls. PwBPPV also walked slower during head rotations. After PRM, gait velocity during level walking increased significantly, and gait became safer according to gait assessment scales. Impairments during tandem walking and walking with head rotations did not improve. The number of fallers was significantly higher for pwBPPV than for controls. After treatment, the number of falls, number of pwBPPV who fell, and fear of falling decreased. DISCUSSION AND CONCLUSIONS: BPPV increases the odds of falls and negatively impacts spatiotemporal parameters of gait. PRM improves falls, fear of falling, and gait during level walking. Additional rehabilitation might be necessary to improve gait while walking with head movements or tandem walking.Video Abstract available for more insights from the authors (see the Supplemental Digital Content Video, available at: http://links.lww.com/JNPT/A421 ).

The accuracy of commercially available instrumented insoles (ARION) for measuring spatiotemporal running metrics.

Spatiotemporal metrics such as step frequency have been associated with running injuries in some studies. Wearables can measure these metrics and provide real-time feedback in-field, but are often not validated. This study assessed the validity of commercially available wireless instrumented insoles (ARION) for quantifying spatiotemporal metrics during level running at different speeds (2.78-5.0 m s-1 ,) and slopes (3° and 6° up/downhill) to an instrumented treadmill. Mean raw, percentage and absolute percentage error, and limits of agreement (LoA) were calculated. Agreement was statistically quantified using four thresholds: excellent, <5%; good, <10%; acceptable, <15%; and poor, >15% error. Excellent agreement (<5% error) was achieved for stride time across all conditions, and for step frequency across all but one condition with good agreement. Contact time and swing time generally showed at least good agreement. The mean difference across all conditions was -0.95% for contact time, 0.11% for stride time, 0.6% for swing time, -0.11% for step frequency, and -0.09% when averaged across all outcomes and conditions. The accuracy at an individual level was generally good to excellent, being <10% for all but two conditions, with these conditions being <15%. Additional experiments among four runners showed that step length could also be measured with an accuracy of 1.76% across different speeds with an updated version of the insoles. These findings suggests that the ARION wearable may not only be useful for large-scale in-field studies investigating group differences, but also to quantify spatiotemporal metrics with generally good to excellent accuracy for individual runners.

The accuracy of markerless motion capture combined with computer vision techniques for measuring running kinematics.

BACKGROUND: Markerless motion capture based on low-cost 2-D video analysis in combination with computer vision techniques has the potential to provide accurate analysis of running technique in both a research and clinical setting. However, the accuracy of markerless motion capture for assessing running kinematics compared to a gold-standard approach remains largely unexplored. OBJECTIVE: Here, we investigate the accuracy of custom-trained (DeepLabCut) and existing (OpenPose) computer vision techniques for assessing sagittal-plane hip, knee, and ankle running kinematics at speeds of 2.78 and 3.33 m s-1 as compared to gold-standard marker-based motion capture. METHODS: Differences between the markerless and marker-based approaches were assessed using statistical parameter mapping and expressed as root mean squared errors (RMSEs). RESULTS: After temporal alignment and offset removal, both DeepLabCut and OpenPose showed no significant differences with the marker-based approach at 2.78 m s-1 , but some significant differences remained at 3.33 m s-1 . At 2.78 m s-1 , RMSEs were 5.07, 7.91, and 5.60, and 5.92, 7.81, and 5.66 degrees for the hip, knee, and ankle for DeepLabCut and OpenPose, respectively. At 3.33 m s-1 , RMSEs were 7.40, 10.9, 8.01, and 4.95, 7.45, and 5.76 for the hip, knee, and ankle for DeepLabCut and OpenPose, respectively. CONCLUSION: The differences between OpenPose and the marker-based method were in line with or smaller than reported between other kinematic analysis methods and marker-based methods, while these differences were larger for DeepLabCut. Since the accuracy differed between individuals, OpenPose may be most useful to facilitate large-scale in-field data collection and investigation of group effects rather than individual-level analyses.

The effect of perturbation-based balance training on balance control and fear of falling in older adults: a single-blind randomised controlled trial.

BACKGROUND: Perturbation-based balance training (PBT) is an emerging intervention shown to improve balance recovery responses and reduce falls in everyday life in older adults. However, perturbation interventions were heterogeneous in nature and need improvement. This study aims to investigate the effects of a PBT protocol that was designed to address previously identified challenges of PBT, in addition to usual care, on balance control and fear of falling in older adults at increased risk of falling. METHODS: Community-dwelling older adults (age ≥ 65 years) who visited the hospital outpatient clinic due to a fall incident were included. Participants received PBT in addition to usual care (referral to a physiotherapist) versus usual care alone. PBT consisted of three 30-minute sessions in three weeks. Unilateral treadmill belt accelerations and decelerations and platform perturbations (shifts and tilts) were applied during standing and walking on the Computer Assisted Rehabilitation Environment (CAREN, Motek Medical BV). This dual-belt treadmill embedded in a motion platform with 6 degrees of freedom is surrounded by a 180° screen on which virtual reality environments are projected. Duration and contents of the training were standardised, while training progression was individualised. Fear of falling (FES-I) and balance control (Mini-BESTest) were assessed at baseline and one week post-intervention. Primary analysis compared changes in outcome measures between groups using Mann-Whitney U tests. RESULTS: Eighty-two participants were included (PBT group n = 39), with a median age of 73 years (IQR 8 years). Median Mini-BESTest scores did not clinically relevantly improve and were not significantly different between groups post-intervention (p = 0.87). FES-I scores did not change in either group. CONCLUSIONS: Participation in a PBT program including multiple perturbation types and directions did not lead to different effects than usual care on clinical measures of balance control or fear of falling in community-dwelling older adults with a recent history of falls. More research is needed to explore how to modulate PBT training dose, and which clinical outcomes are most suitable to measure training effects on balance control. TRIAL REGISTRATION: Nederlands Trial Register NL7680. Registered 17-04-2019 - retrospectively registered. https://www.trialregister.nl/trial/7680 .

Muscle forces and fascicle behavior during three hamstring exercises.

Knowledge about muscular forces and fascicle behavior during hamstring exercises can optimize exercise prescription, but information on these outcomes across different exercises is lacking. We aimed to characterize and compare lower-limb muscle forces and biceps femoris long head muscle fascicle behavior between three hamstring exercises: the Nordic hamstring curl (NHC), single-leg Roman chair (RCH), and single-leg deadlift (DL). Ten male participants performed the exercises while full-body kinematics, ground reaction forces, surface muscle activation, and biceps femoris long head fascicle behavior were measured. Mean fascicle length was highest in the DL, followed by the RCH and NHC. Fascicle lengthening was higher in the NHC compared with the RCH and DL, with no difference between the RCH and DL. Biceps femoris short and long head, semitendinosus, and semimembranosus peak forces were generally higher in the NHC compared with the RCH and DL, while mean forces during the eccentric phase were generally not different between the NHC and RCH. Peak forces in the NHC coincided with low biceps femoris long head and semimembranosus muscle activation. The NHC generally has the highest peak hamstring muscle forces and results in more fascicle lengthening when compared to the DL and RCH. The NHC may therefore be most effective to promote increases in fascicle length. While the NHC may be effective to promote biceps femoris short head and semitendinosus strength adaptations, the RCH and DL may be more effective to promote strength increases in the biceps femoris long head and semimembranosus.

A randomized crossover study of functional electrical stimulation during walking in spastic cerebral palsy: the FES on participation (FESPa) trial.

BACKGROUND: Spastic cerebral palsy is the most common cause of motor disability in children. It often leads to foot drop or equinus, interfering with walking. Ankle-foot orthoses (AFOs) are commonly used in these cases. However, AFOs can be too restrictive for mildly impaired patients. Functional electrical stimulation (FES) of the ankle-dorsiflexors is an alternative treatment as it could function as a dynamic functional orthosis. Despite previous research, high level evidence on the effects of FES on activities and participation in daily life is missing. The primary aim of this study is to evaluate whether FES improves the activity and participation level in daily life according to patients, and the secondary aim is to provide evidence of the effect of FES at the level of body functions and activities. Furthermore, we aim to collect relevant information for decisions on its clinical implementation. METHODS: A randomized crossover trial will be performed on 25 children with unilateral spastic cerebral palsy. Patients aged between 4 and 18 years, with Gross Motor Functioning Classification System level I or II and unilateral foot drop of central origin, currently treated with AFO or adapted shoes, will be included. All participants will undergo twelve weeks of conventional treatment (AFO/adapted shoes) and 12 weeks of FES treatment, separated by a six-week washout-phase. FES treatment consists of wearing the WalkAide® device, with surface electrodes stimulating the peroneal nerve during swing phase of gait. For the primary objective, the Goal Attainment Scale is used to test whether FES improves activities and participation in daily life. The secondary objective is to prove whether FES is effective at the level of body functions and structures, and activities, including ankle kinematics and kinetics measured during 3D-gait analysis and questionnaire-based frequency of falling. The tertiary objective is to collect relevant information for clinical implementation, including acceptability using the device log file and side effect registration, cost-effectiveness based on quality adjusted life years (QALYs) and clinical characteristics for patient selection. DISCUSSION: We anticipate that the results of this study will allow evidence-based use of FES during walking in children with unilateral spastic cerebral palsy. TRIAL REGISTRATION: ClinicalTrials.gov : NCT03440632 .

Gait analysis and clinical outcome in patients after pilon fracture surgery.

BACKGROUND: In this study kinematic parameters, radiographic findings and PROM in pilon fractures after operative treatment were compared with healthy subjects. METHODS: 16 patients treated with osteosynthesis after pilon fracture underwent kinematic analysis with the OFM. Fractures were evaluated for post-operative step-off and gap on CT-scans and PROM were collected. Results were compared to 10 healthy persons. RESULTS: Range of motion (ROM) crural was lower in the flexion/extension for pilon fractures (10.03 vs. 13.15, p = 0.017). The ROM in the inversion/eversion was low, but ROM in the abduction/adduction was higher. Correlations were found between flexion/extension and AO-classification (r = -0.357 p < 0.05), PROM score of the AOFAS (r = 0.445 p < 0.01), post-operative gap and step-off in the tibia plafond. CONCLUSION: Pilon fractures showed decreased ROM between the hindfoot and tibia in the sagittal and transverse plane, but increased ROM in the frontal plane during push-off phase as compensatory kinetics. ROM showed significant correlations with PROM and intra-articular step-off and gap in the tibia plafond.

Gait analysis of foot compensation in symptomatic Hallux Rigidus patients.

BACKGROUND: Compensatory motion of foot joints in hallux rigidus (HR) are not fully known. This study aimed to clarify the kinematic compensation within the foot and to detect whether this affects plantar pressure distribution. METHODS: Gait characteristics were assessed in 16 patients (16 feet) with HR and compared with 15 healthy controls (30 feet) with three-dimensional gait analysis by using the multi-segment Oxford Foot Model, measuring spatio-temporal parameters, joint kinematics and plantar pressure. RESULTS: HR subjects showed less hallux plantar flexion during midstance and less hallux dorsiflexion during push-off, while increased forefoot supination was detected during push-off. No significant differences in plantar pressure were detected. Step length was significantly smaller in HR subjects, while gait velocity was comparable between groups. CONCLUSIONS: HR significantly affects sagittal hallux motion, and the forefoot compensates by an increased supination during push-off. Despite this kinematic compensatory mechanism, no significant differences in plantar loading were detected.

Perturbation-based balance training to improve balance control and reduce falls in older adults - study protocol for a randomized controlled trial.

BACKGROUND: Falls are a common cause of injuries and hospitalization among older adults. While conventional balance training appears effective in preventing falls, a relatively large number of training sessions are needed and retention of the effects after the training period is hard to accomplish. This may be because these interventions are not sufficiently task-specific for the mechanism of falls. Many falls in older adults occur due to unexpected external perturbations during gait, such as trips. Therefore, there is increasing interest in perturbation-based balance training (PBT), which is a more task-specific intervention to improve reactive balance control after unexpected perturbations. The literature suggests that PBT may be more effective and require fewer training sessions to reduce falls incidence in older adults, than conventional balance training. We aim to evaluate the effect of a three-session PBT protocol on balance control, daily life falls and fear of falling. Secondly, we will evaluate the acceptability of the PBT protocol. METHODS: This is a mixed-methods study combining a single-blind (outcome assessor) randomized controlled trial (RCT) using a parallel-group design, and qualitative research evaluating the acceptability of the intervention. The study sample consists of community-dwelling older adults aged 65 years and older who have recently fallen and visited the MUMC+ outpatient clinic. Subjects are randomized into two groups. The control group (n = 40) receives usual care, meaning referral to a physical therapist. The intervention group (n = 40) receives usual care plus three 30-min sessions of PBT in the Computer Assisted Rehabilitation Environment. Subjects' balance control (Mini-BESTest) and fear of falling (FES-I) will be assessed at baseline, and 4 weeks and 3 months post-baseline. Daily life falls will be recorded with falls calendars until 6 months after the first follow-up measurement, long-term injurious falls will be recorded at 2-years' follow-up via the electronic patient record. Acceptability of the PBT protocol will be evaluated with semi-structured interviews in a subsample from the intervention group. DISCUSSION: This study will contribute to the evidence for the effectiveness of PBT using a training protocol based on the available literature, and also give much needed insights into the acceptability of PBT for older adults. TRIAL REGISTRATION: Nederlands Trial Register NL7680 . Registered 17-04-2019 - retrospectively registered.

Optimization and Validation of a Classification Algorithm for Assessment of Physical Activity in Hospitalized Patients.

Low amounts of physical activity (PA) and prolonged periods of sedentary activity are common in hospitalized patients. Objective PA monitoring is needed to prevent the negative effects of inactivity, but a suitable algorithm is lacking. The aim of this study is to optimize and validate a classification algorithm that discriminates between sedentary, standing, and dynamic activities, and records postural transitions in hospitalized patients under free-living conditions. Optimization and validation in comparison to video analysis were performed in orthopedic and acutely hospitalized elderly patients with an accelerometer worn on the upper leg. Data segmentation window size (WS), amount of PA threshold (PA Th) and sensor orientation threshold (SO Th) were optimized in 25 patients, validation was performed in another 25. Sensitivity, specificity, accuracy, and (absolute) percentage error were used to assess the algorithm's performance. Optimization resulted in the best performance with parameter settings: WS 4 s, PA Th 4.3 counts per second, SO Th 0.8 g. Validation showed that all activities were classified within acceptable limits (>80% sensitivity, specificity and accuracy, ±10% error), except for the classification of standing activity. As patients need to increase their PA and interrupt sedentary behavior, the algorithm is suitable for classifying PA in hospitalized patients.

One-leg inactivity induces a reduction in mitochondrial oxidative capacity, intramyocellular lipid accumulation and reduced insulin signalling upon lipid infusion: a human study with unilateral limb suspension.

AIMS/HYPOTHESIS: Physical inactivity, low mitochondrial function, increased intramyocellular lipid (IMCL) deposition and reduced insulin sensitivity are common denominators of chronic metabolic disorders, like obesity and type 2 diabetes. Yet, whether low mitochondrial function predisposes to insulin resistance in humans is still unknown. METHODS: Here we investigated, in an intervention study, whether muscle with low mitochondrial oxidative capacity, induced by one-legged physical inactivity, would feature stronger signs of lipid-induced insulin resistance. To this end, ten male participants (age 22.4 ± 4.2 years, BMI 21.3 ± 2.0 kg/m2) underwent a 12 day unilateral lower-limb suspension with the contralateral leg serving as an active internal control. RESULTS: In vivo, mitochondrial oxidative capacity, assessed by phosphocreatine (PCr)-recovery half-time, was lower in the inactive vs active leg. Ex vivo, palmitate oxidation to 14CO2 was lower in the suspended leg vs the active leg; however, this did not result in significantly higher [14C]palmitate incorporation into triacylglycerol. The reduced mitochondrial function in the suspended leg was, however, paralleled by augmented IMCL content in both musculus tibialis anterior and musculus vastus lateralis, and by increased membrane bound protein kinase C (PKC) θ. Finally, upon lipid infusion, insulin signalling was lower in the suspended vs active leg. CONCLUSIONS/INTERPRETATION: Together, these results demonstrate, in a unique human in vivo model, that a low mitochondrial oxidative capacity due to physical inactivity directly impacts IMCL accumulation and PKCθ translocation, resulting in impaired insulin signalling upon lipid infusion. This demonstrates the importance of mitochondrial oxidative capacity and muscle fat accumulation in the development of insulin resistance in humans. TRIAL REGISTRATION: ClinicalTrial.gov NCT01576250. FUNDING: PS was supported by a 'VICI' Research Grant for innovative research from the Netherlands Organization for Scientific Research (Grant 918.96.618).

Daily Life Benefits and Usage Characteristics of Dynamic Arm Supports in Subjects with Neuromuscular Disorders.

Neuromuscular disorders cause progressive muscular weakness, which limits upper extremity mobility and performance during activities of daily life. Dynamic arm supports can improve mobility and quality of life. However, their use is often discontinued over time for unclear reasons. This study aimed to evaluate whether users of dynamic arm supports demonstrate and perceive quantifiable mobility benefits over a period of two months. Nine users of dynamic arm supports were included in this observational study. They had different neuromuscular disorders and collectively used four different arm supports. They were observed for three consecutive weeks during which they were equipped with a multi-sensor network of accelerometers to assess the actual use of the arm support and they were asked to provide self-reports on the perceived benefits of the devices. Benefits were experienced mainly during anti-gravity activities and the measured use did not change over time. The self-reports provided contextual information in domains such as participation to social life, in addition to the sensor system. However self-reports overestimated the actual use by up to three-fold compared to the accelerometer measures. A combination of objective and subjective methods is recommended for meaningful and quantifiable mobility benefits during activities of daily life.

Mechanical Properties of Treadmill Surfaces Compared to Other Overground Sport Surfaces.

The mechanical properties of the surfaces used for exercising can affect sports performance and injury risk. However, the mechanical properties of treadmill surfaces remain largely unknown. The aim of this study was, therefore, to assess the shock absorption (SA), vertical deformation (VD) and energy restitution (ER) of different treadmill models and to compare them with those of other sport surfaces. A total of 77 treadmills, 30 artificial turf pitches and 30 athletics tracks were assessed using an advanced artificial athlete device. Differences in the mechanical properties between the surfaces and treadmill models were evaluated using a repeated-measures ANOVA. The treadmills were found to exhibit the highest SA of all the surfaces (64.2 ± 2; p < 0.01; effect size (ES) = 0.96), while their VD (7.6 ± 1.3; p < 0.01; ES = 0.87) and ER (45 ± 11; p < 0.01; ES = 0.51) were between the VDs of the artificial turf and track. The SA (p < 0.01; ES = 0.69), VD (p < 0.01; ES = 0.90) and ER (p < 0.01; ES = 0.89) were also shown to differ between treadmill models. The differences between the treadmills commonly used in fitness centers were much lower than differences between the treadmills and track surfaces, but they were sometimes larger than the differences with artificial turf. The treadmills used in clinical practice and research were shown to exhibit widely varying mechanical properties. The results of this study demonstrate that the mechanical properties (SA, VD and ER) of treadmill surfaces differ significantly from those of overground sport surfaces such as artificial turf and athletics track surfaces but also asphalt or concrete. These different mechanical properties of treadmills may affect treadmill running performance, injury risk and the generalizability of research performed on treadmills to overground locomotion.

A Proposed Method to Assess the Mechanical Properties of Treadmill Surfaces.

The aim of this study was to define a reliable and sensitive test method for assessing Shock Absorption (SA), Vertical Deformation (VD), and Energy Restitution (ER) in treadmill surfaces. A total of 42 treadmills belonging to four different models were included in the study: (a) Technogym Jog700 Excite (n = 10), (b) Technogym Artis Run (n = 12), (c) LifeFitness Integrity Series 97T (n = 11), and (d) LifeFitness Integrity Series DX (n = 9). An advanced artificial athlete (AAA) device was used to assess SA, VD, and ER at three different locations along the longitudinal axis of each treadmill and in the support area of the athletes' feet. For each location, our results show that the error assumed when performing one impact with the AAA instead of three (SA ≤ |0.1|%, VD ≤ |0.0| mm, and ER ≤ |0.2|%) is lower than the smallest changes that can be detected by the measuring device (SA = 0.4%, VD = 0.2 mm, and ER = 0.9%). Also, our results show the ability of the test method to detect meaningful differences between locations once the one-impact criterium is adopted, since absolute minimum differences between zones (SA: |0.6|%, VD: |0.3| mm, and ER: |1.2|%) were above the uncertainty of the measuring device. Therefore, performing a single impact with the AAA in each of the three locations described in this study can be considered a representative and reliable method for assessing SA, VD, and ER in treadmill surfaces.

The immediate influence of implicit motor learning strategies on spatiotemporal gait parameters in stroke patients: a randomized within-subjects design.

OBJECTIVES:: To investigate immediate changes in walking performance associated with three implicit motor learning strategies and to explore patient experiences of each strategy. DESIGN:: Participants were randomly allocated to one of three implicit motor learning strategies. Within-group comparisons of spatiotemporal parameters at baseline and post strategy were performed. SETTING:: Laboratory setting. SUBJECTS:: A total of 56 community-dwelling post-stroke individuals. INTERVENTIONS:: Implicit learning strategies were analogy instructions, environmental constraints and action observation. Different analogy instructions and environmental constraints were used to facilitate specific gait parameters. Within action observation, only videotaped gait was shown. MAIN MEASURES:: Spatiotemporal measures (speed, step length, step width, step height) were recorded using Vicon 3D motion analysis. Patient experiences were assessed by questionnaire. RESULTS:: At a group level, three of the four analogy instructions ( n = 19) led to small but significant changes in speed ( d = 0.088 m/s), step height (affected side d = 0.006 m) and step width ( d = -0.019 m), and one environmental constraint ( n = 17) led to significant changes in step width ( d = -0.040 m). At an individual level, results showed wide variation in the magnitude of changes. Within action observation ( n = 20), no significant changes were found. Overall, participants found it easy to use the different strategies and experienced some changes in their walking performance. CONCLUSION:: Analogy instructions and environmental constraints can lead to specific, immediate changes in the walking performance and were in general experienced as feasible by the participants. However, the response of an individual patient may vary quite considerably.