Peter J Beek

Vrije Universiteit Amsterdam | VU · Human Movement Sciences

A literature review is presented about the hydrodynamic effects of different hand and arm movements during swimming with the aim to identify lacunae in current methods and knowledge, and to distil practical guidelines for coaches and swimmers seeking to increase swimming speed. Experimental and numerical studies are discussed examining the effects...

Introduction: Balance performance in the elderly is related to psychological factors such as attentional focus. We investigated the effects of internal vs. external focus of attention and fall history on walking stability in healthy older adults. Method: Walking stability of twenty-eight healthy older adults was assessed by applying random unila...

Background The ability to adjust walking to environmental context is often reduced in older adults and, partly as result of this, falls are common in this population. A treadmill with visual context projected on its belt (e.g., obstacles and targets) allows for practicing step adjustments relative to that context, while concurrently exploiting the...

Background: Research is lacking on body-related consequences of sexual abuse in adults with mild intellectual disability or borderline intellectual functioning (MID-BIF), although the prevalence of abuse is high and body-and movement-oriented diagnostics and therapeutics seem warranted for this group. Method: Body experience in adults with MID-BIF...

Background The duty factor (reflecting the ratio of stance to flight time) is an important variable related to running performance, economy, and injury risk. According to the dual-axis model, the duty factor and the cadence are sufficient to describe an individual’s running style at a certain speed. To test this model, one should be able to modulat...

Although the tumble turn in swimming has been studied extensively, no consensus exists about which measure is best suited to capture its performance. The aim of this study was to better understand the implications of choosing a particular distance-based performance measure for assessing and investigating tumble turn performance in freestyle swimmin...

Race time can be shortened by improving turn performance in competitive swimming, but this requires insight into the optimal turn technique. The aim of the present study was to examine the effect of Wall Contact Time (WCT) and Tuck Index on tumble turn performance and their interrelations by experimentally manipulating both variables, which has not...

To date, optimal propulsion in swimming has been studied predominantly using physical or computational models of the arm and seldom during real-life swimming. In the present study we examined the contributions of selected power, technique and anthropometric measures on sprint performance during arms-only front crawl swimming. To this end, 25 male a...

Background The ability to adapt walking to environmental properties and hazards, a prerequisite for safe ambulation, is often impaired in persons after stroke. Research question The aim of this study was to compare the efficacy of two walking-adaptability interventions: a novel treadmill-based C-Mill therapy (using gait-dependent augmented reality...

Instrumented earbuds equipped with accelerometers were developed in response to limitations of currently used running wearables regarding sensor location and feedback delivery. The aim of this study was to assess test–retest reliability, face validity and concurrent validity for cadence and stance time in running. Participants wore an instrumented...

Background Increasing cadence in running has been advocated as a means to improve performance and reduce impact forces. Although acoustic pacing can be used for this purpose, it might by itself lead to an increased impact force, which would counteract the decrease in impact force that is being pursued by increasing the cadence with acoustic pacing...

Background Body experience is an important facet of psychosocial functioning and health. However, to date no test exists to measure body experience in adults with mild intellectual disability and borderline intellectual functioning (MID-BIF). We therefore adapted the Body Experience Questionnaire (BEQ) to this group, resulting in the BEQ-mb, and ev...

Running movements are parametrised using a wide variety of devices. Misleading interpretations can be avoided if the interdependencies and redundancies between biomechanical parameters are taken into account. In this synthetic review, commonly measured running parameters are discussed in relation to each other, culminating in a concise, yet compreh...

Background The ability to adapt walking to environmental properties and hazards, a prerequisite for safe ambulation, is often impaired in persons after stroke. Research question The aim of this study was to compare the efficacy of two walking-adaptability interventions: treadmill-based C-Mill therapy (using gait-dependent augmented reality) and the...

The large-scale usage of smartphone applications and sports watches in running provides the potential to lower injury risk and improve performance. To achieve these common goals, contextual factors need to be taken into account to provide users with accurate and personal feedback. This thesis aims to develop methods to improve the quality of wearab...

The dive start is an important component of competitive swimming, especially at shorter race distances. Previous research has suggested that start performance depends on kinematic variables pertaining to the swimmer at water entry, notably the distance from the block, the horizontal velocity of the centre of mass and the angle between body and wate...

ACHTERGROND Seksueel misbruik bij mensen met een (boven)gemiddeld iq is gerelateerd aan een breed scala van zowel gedragsmatige als psychologische klinische kenmerken, inclusief kenmerken die de lichaamsbeleving betreffen. Onderzoek naar de klinische kenmerken van seksueel misbruik bij mensen met een lichte verstandelijke beperking (lvb) is echter...

The stability of rhythmic interlimb coordination is governed by the coupling between limb movements. While it is amply documented how coordinative performance depends on movement frequency, theoretical considerations and recent empirical findings suggest that interlimb coupling (and hence coordinative stability) is actually mediated more by movemen...

In road cycling, cyclists strategically use their energetic resources in unique race-specific circumstances. For time-trial events, professional cycling teams design pacing plans aimed at the effective management of anaerobic work capacities of individual cyclists, allowing for more consistent speeds and therefore, faster times. Patently, adherence...

A change in cadence during walking or running might be indicated for a variety of reasons, among which mobility improvement and injury prevention. In a within-subject study design, we examined whether walking or running cadences are modulated best by means of step-based or stride-based auditory pacing. Sixteen experienced runners walked and ran on...

Mixed-reality technologies are evolving rapidly, allowing for gradually more realistic interaction with digital content while moving freely in real-world environments. In this study, we examined the suitability of the Microsoft HoloLens mixed-reality headset for creating locomotor interactions in real-world environments enriched with 3D holographic...

Background: Sexual abuse in individuals with (above) average iq is associated with a wide range of behavioural and psychological clinical characteristics, including characteristics regarding body experience. However, research on the clinical characteristics of sexually abused individuals with borderline intellectual functioning or mild intellectua...

To assess the efficacy of body‐ and movement‐oriented interventions (BMOIs) in traumatized adults with posttraumatic stress disorder (PTSD), we conducted a systematic review and meta‐analysis of pertinent literature. Four bibliographical databases (PsycINFO, Ovid MEDLINE(R), EMBASE, and the Cochrane Central Register of Controlled Trials) were searc...

Indeed the abstract now contains more words. Please correct to: The aim of the study was to investigate whether jerk cost (JC) can discriminate between swimming levels. Nine elite and nine non-elite swimmers swam a 50-m front-crawl sprint wearing a 3D accelerometer on their back between the inferior angles of the scapulae. Lap times and JC were cal...

Bij de ziekte van Parkinson zijn evenwichtsproblemen niet ongewoon. Aanvullende visuele feedback over de zwaaibewegingen van het lichaam tijdens het staan kan de prestatie op een houdingstaak verbeteren en balanstraining ondersteunen. Tegelijkertijd lijken mensen met parkinson extra afhankelijk te zijn van visuele informatie. Ze zijn daarmee mogeli...

Background: Treadmill training augmented with visual images projected on the belt's surface may help improve walking adaptability. Moreover, patient-tailored automatization and standardization may increase the feasibility of walking-adaptability therapy. We developed C-Gait, a treadmill protocol consisting of a baseline walking-adaptability assess...

The purpose of the present study was to identify factors that underlie differences among runners in stride frequency (SF) as a function of running speed. Participants (N = 256; 85.5% males and 14.5% females; 44.1 ± 9.8 years; 181.4 ± 8.4 cm; 75.3 ± 10.6 kg; mean ± SD) shared their wearable data (Garmin Inc). Individual datasets were filtered to ob...

For feedback to be effective, we must first identify relevant performance indicators for speed skating. We instrumented the skating of 10 junior elite Dutch speed skaters with two inertial measurement units during two competition events. Contact time, stroke frequency and other parameters were derived from collected IMU data and related to performa...

Purpose: Athletes require feedback in order to comply with prescribed training programs designed to optimize their performance. In rowing, current feedback parameters on intensity are inaccurate. Mechanical power output is a suitable objective measure for training intensity, but - due to movement restrictions related to crew rowing - it is uncerta...

INTRODUCTION: Rowing performance (i.e. the average shell velocity) can be analysed in terms of a power equation describing what part of a rower's mechanical power output contributes to shell velocity and what is lost to other factors [1]. To optimize performance, valid quantitative feedback can now be provided on parameters related to this equation...

Mechanical power output is a key performance-determining variable in many cyclic sports. In rowing, instantaneous power output is commonly determined as the dot product of handle force moment and oar angular velocity. The aim of this study was to show that this commonly used proxy is theoretically flawed and to provide an indication of the magnitud...

Cognitive-motor interference may contribute to the risk of falling in people with stroke, as may be the associated phenomenon of inappropriate task prioritization. Examining dual-task walking could provide valuable insights as to how to best evaluate and treat walking in people with stroke. This study aimed to examine the effect of different walkin...

The ability to stand up from a sitting position is essential for older adults to live independently. Body-fixed inertial sensors may provide an approach for quantifying the sit-to-stand (STS) in clinical settings. The aim of this study was to determine whether measurements of STS movements using body-fixed sensors yield parameters that are informat...

Objective: In patients with Parkinson’s disease (PD), augmented visual feedback (VF) can improve functional motor performance. Conversely, they appear to rely more on visual information than healthy subjects, which is unfavorable when this information is unreliable. Cortical beta activity is thought to be associated with the need for motor adaptati...

Objectives: The study of sequential effects in aiming tasks might shed light on the organization of repetitive motor performances over time. To date, investigations of such effects in sports have been limited and yielded mixed results. Given the relatively short time intervals between successive attempts, and the absence of defensive interventions,...

This paper evaluates a new and adaptive real-time cadence detection algorithm (CDA) for unconstrained sensor placement during walking and running. Conventional correlation procedures, dependent on sensor position and orientation, may alternately detect either steps or strides and consequently suffer from false negatives or positives. To overcome th...

Posttraumatic stress disorder (PTSD) is associated with an increased risk of physical disorders as a consequence of chronic stress reactions and adverse lifestyle behaviours. In addition, various other physical signs and symptoms may be present, as well as problems with emotional awareness, such as alexithymia, which may impede verbal information p...

During running at a constant speed, the optimal stride frequency (SF) can be derived from the u-shaped relationship between SF and heart rate (HR). Changing SF towards the optimum of this relationship is beneficial for energy expenditure and may positively change biomechanics of running. In the current study, the effects of speed on the optimal SF...

SFxHRxV. Data used for the model fitting. With respectively subject number, condition order, speed (m/s), stride frequency (spm), heart rate (bpm). (XLSX)

In swimming propelling efficiency is partly determined by intra-cyclic velocity fluctuations. The higher these fluctuations are at a given average swimming velocity, the less efficient is the propulsion. This study explored whether the leg-arm coordination (i.e. phase relation ϕ) within the breaststroke cycle can be influenced with acoustic pacing,...

An exemplary movie of the automated tracking algorithm. (MP4)

Zip-file with tracking data. (ZIP)

Datasheet used for the statistical analysis. (SAV)

Simulation 2. Effect of short‐latency moment on upper body across flexible hip.

Appendix S1. Averaged GVS response.

Simulation 1. Effect of short‐latency moment on inverted pendulum CoM.

Simulation 3. Effect of short‐latency moments on upper body across flexible knee.

Simulation 4. Effect of short‐latency moment on upper body across flexible lower‐limb.

Simulation 5. Effect of neck moment on head and body below the neck.

Vestibular sensation contributes to cervical-head stabilization and fall prevention. To what extent fear of falling influences the associated vestibular feedback processes is currently undetermined. We used galanic vestibular stimulation (GVS) to induce vestibular reflexes while participants stood at ground level and on a narrow walkway at 3.85 m h...

The ability to adjust walking to environmental context is often reduced in older adults and falls are common in this population. Adaptability treadmill training (ATT) was developed to practice step adjustments relative to context projected on the belt (e.g., obstacles and targets), while concurrently exploiting the great amounts of walking practice...

The aim of the current study is to evaluate several performance indicators to be used as real-time feedback in the coming experiments to enhance performance of elite speeds skaters. Six speed skaters, wearing one IMU per skate, collected data over one full training season to evaluate and pinpoint useful performance indicators. Promising performance...

It has often been shown that performance and learning in movement tasks may be improved by focusing on the effect of the movement in the environment (external focus of attention) instead of the movement itself (internal focus of attention). Nevertheless, most coaching instructions and feedback information given in sports seem to favor an internal f...

Background: Coaches in elite swimming carefully design the training programs of their swimmers and are keen on achieving strict adherence to those programs by their athletes. At present, coaches usually monitor the compliance of their swimmers to the training program with a stopwatch. However, this measurement clearly limits the monitoring possibil...

Objectives: The aims of this study were (1) to quantify and compare the load of a professional football team's training days and matches and (2) to compare training of nonstarters the day after the match with regular training of starters and nonstarters. Methods: On-field training load during in-season training days (categorized as days before matc...

Falls represent a substantial risk in the elderly. Previous studies have found that a focus on the outcome or effect of the movement (external focus of attention) leads to improved balance performance, whereas a focus on the movement execution itself (internal focus of attention) impairs balance performance in elderly. A shift toward more conscious...

For training to be optimal, daily training load has to be adapted to the momentary status of the individual athlete, which is often difficult to establish. Therefore, the present study was performed to investigate the predictive value of heart rate recovery (HRR) during a standardized warm-up for training load. Training load was quantified by the v...

Background Walking in everyday life requires the ability to adapt walking to the environment. This adaptability is often impaired after stroke, and this might contribute to the increased fall risk after stroke. To improve safe community ambulation, walking adaptability training might be beneficial after stroke. This study is designed to compare the...