Daniel Hamacher

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Verified

Daniel verified their affiliation via an institutional email.

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• PhD
• Research Associate at Friedrich Schiller University Jena

Introduction Multiple sclerosis (MS) is a chronic autoimmune disease affecting the central nervous system, leading to motor and cognitive impairment. These impairments become especially evident during dual-tasks, such as walking while performing a cognitive activity. Previous research has highlighted changes in gait-specific parameters during dual-...

The present study investigated the role of early visual experience in the development of postural control (balance) and locomotion (gait). In a cross-sectional design, balance and gait were assessed in 59 participants (ages 7–43 years) with a history of (a) transient congenital blindness, (b) transient late-onset blindness, (c) permanent congenital...

Backround Foot strike pattern (FSP) is defined by the way the foot makes initial ground contact and is influenced by intrinsic and extrinsic factors. This study investigated the effect of running speed on asymmetries of FSP. Methods Seventeen female and nineteen male soccer players performed an incremental running test on an instrumented treadmill...

Maintaining sufficient muscle strength is fundamental to prevent a decline in basic physical functions such as gait, and is therefore a prerequisite for a healthy independent life in older people. However, the relationship between gait parameters and the strength of single muscle groups is reported with inconclusive results. The objective of this s...

Background Currently, there are several studies showing that wearable inertial sensors are highly sensitive in the detection of gait disturbances in people with multiple sclerosis (PwMS), showing excellent reliability within one or 7–14 days. However, it is not known how stable these gait parameters remain over a longer period of time. This is surp...

Running stability is the ability to withstand naturally occurring minor perturbations during running. It is susceptible to external and internal running conditions such as footwear or fatigue. However, both its reliable measurability and the extent to which laboratory measurements reflect outdoor running remain unclear. This study aimed to evaluate...

The research on success factors in elite sport focuses primarily on the one hand to sport in its entirety and on the other hand to the prediction of success in individual sporting events, especially in soccer. In this paper, we investigate the existence of a first-mover advantage for national team sports, which has a long-term impact on a nation's...

In sports, some nations are very successful in a specific sport over a long period of time. In this paper, the concept of "first mover advantage" is used to explain this phenomenon. We provide preliminary evidence for the connection between early specialization and success for the team sports soccer, volleyball, handball, ice hockey, and rugby. To...

Background The aim of the current study was to examine multiple gait parameters obtained by wearable inertial sensors and their sensitivity to clinical status in early multiple sclerosis (MS). Further, a potential correlation between gait parameters and subjective fatigue was explored. Methods Automated gait analyses were carried out on 88 MS pati...

The evaluation of local divergence exponent (LDE) has been proposed as a common gait stability measure in people with multiple sclerosis (PwMS). However, differences in methods of determining LDE may lead to different results. Therefore, the purpose of the current study was to determine the effect of different sensor locations and LDE measures on t...

Background American football players need the ability to provide maximal muscular power in a modicum of time. Postactivation performance enhancement (PAPE), which is characterized by an acute improvement of a performance measure following conditioning contractions, could be of value for American football players. The aim of the present study was to...

Background Individuals with chronic ankle instability (CAI) have an increased risk for recurrent injuries. The preventive effects of external ankle supports are not fully understood. This study aimed to examine the effect of elastic ankle support on running ankle kinematics. Methods 3D running gait analysis of individuals with and without CAI was...

Self-motion perception used for locomotion and navigation requires the integration of visual, vestibular, and proprioceptive input. In the absence of vision, postural stability and locomotor tasks become more difficult. Previous research has suggested that in visually deprived children, postural stability and levels of physical activity are overall...

Background While gait stability and variability measures in barefoot and shod locomotion have relatively frequently been investigated in younger adults, little is known for older cohorts. Moreover, most studies have investigated gait measures in laboratory settings instead of real-life settings. Research questions How are gait stability and variab...

Local dynamic running stability is the ability of a dynamic system to compensate for small perturbations during running. While the immediate effects of footwear on running biomechanics are frequently investigated, no research has studied the long-term effects of barefoot vs. shod running on local dynamic running stability. In this randomized single...

Background Regular injury prevention training is not only effective in reducing sports injury rates, but also in improving neuromuscular and performance-related variables. However, it is currently unknown if this effect can be modified by varying the training dosage. Objective To compare the effects of two injury prevention programmes with a diffe...

Background During everyday locomotion, we cope with various internal or external perturbations (e.g. uneven surface). Uncertainty exists on how unpredictable external perturbations increase noise within the motor system and if they are compensated by employing covariation of the limb joints or rather due to decreased sensitivity of an altered postu...

Background: In recent years, minimalist footwear has been increasingly promoted for its use in sportive and recreational activities. These shoes are considered to function naturally like barefoot walking while providing a protective surface. Despite a growing popularity of these shoes in the older population, little is known about the influence of...

Problem: The technology of inertial measurement units (IMU) enables the collection of running biomechanical data under in-field conditions. This paper presents a validation study of an increasingly used IMU system using a corresponding below-ground magnetic timing gate system. Methods: Thirty active healthy participants ran with an IMU located at t...

Dual-task costs of gait (variability) parameters are frequently used to probe the grade of automaticity of walking. However, recent studies reported contradicting dual-task costs for different gait variability measures within the same cohorts. The effects of a dual-task on the gait pattern are, thus, not fully understood. The aim of the current stu...

Diminishing proprioception caused by aging effects is associated with a higher risk to fall. However, existing measurement systems of proprioception are often expensive, time-consuming, or insufficient regarding reliability evaluation. Inertial sensor-based systems could address these issues. Consequently, this study sought to develop and evaluate...

The aim of the current study was to evaluate the effect of a cognitive dual task on minimum toe clearance (MTC) variability while walking. In a randomized cross-over design, gait kinematics of 25 older (70 ± 6 years) and 45 younger adults (25 ± 2 years) were captured during normal walking and dual-task walking. Variability of stride time, stride le...

Context In some patients, ankle sprains lead to chronic symptoms like pain or muscular weakness called chronic ankle instability (CAI). External ankle supports have shown to be effective in preventing sprains and reducing recurrence, but the underlying mechanisms are unclear. Since sensorimotor variables are associated with injury incidence, an inf...

A stable gait pattern is a prerequisite to successfully master various activities of daily living. Furthermore, reduced gait stability is associated with a higher risk of falling. To provide specific intervention strategies to improve gait stability, gaining detailed knowledge of the underlying mechanism and influencing factors is of utmost importa...

Biological maturation is associated with physiological changes which in turn affect motor performance. No study has assessed the association between growing up habitually shod versus habitually barefoot and motor performance in the context of maturation, so this approach is unique. The purpose of this study was to examine the influence of biologica...

Background: Peak height velocity has been reported to be associated with the phenomenon of adolescent awkwardness, a temporary disruption in motor skills, and an increase in injuries in some adolescents. To date, it is not entirely clear which motor abilities are deficient during the phase of rapid growth. Research question: We hypothesized that st...

In the analysis of human walking, the assessment of local dynamic stability (LDS) has been widely used to determine gait stability. To extend the concepts of LDS to the analysis of running biomechanics, this study aimed to compare LDS during exhaustive running between competitive and recreational runners. Fifteen recreational and fifteen competitiv...

Background: While the effects of diseases, performance of proprioceptors, anxiety or pain on gait stability or automaticity of walking are well-explored, physical fatigue might be another relevant factor whose consequences are not sufficiently investigated, yet. Research question: The aim of the current study was to evaluate the effect of physical...

Traditionally, movement variability is considered an indicator for sensorimotor malfunctioning. However, functional movement variability is also a result of compensation mechanisms e.g. to account for prior movement deviations and is, therefore, crucial for stable movements. The aim of this study was to analyze functional variability during motor l...

Auditory information affects sensorimotor control of gait. Noise or active noise cancelling alters the perception of movement related sounds and, probably, gait stability. The aim of the current study was to evaluate the effects of noise cancelling on gait stability. Twenty-five healthy older subjects (70 ± 6 years) were included into a randomized...

During competition, kayak athletes must optimally adapt to environmental factors (e.g. wind, waves) to achieve peak performance. However, the ability to adapt to such perturbations has never been assessed in kayak paddling. Therefore, the aim of the current study was to evaluate the local dynamic stability in sports technique of youth sprint kayak...

Background: While altered foot arch characteristics (high or low) are frequently assumed to influence lower limb biomechanics and are suspected to be a contributing factor for injuries, the association between arch characteristics and lower limb running biomechanics in children is unclear. Research question: Therefore, the aim of this study was...

Gait variability is frequently used to evaluate the sensorimotor system and elderly fallers compared to non-fallers exhibit an altered variability in gait parameters during unchanged conditions. While gait variability is often interpreted as movement error, it is also necessary to change the gait pattern in order to react to internal and external p...

Rhythmic auditory cues aim to modulate step times while walking. Their effect on the variability of minimum foot clearance, which is “normally” the most controlled gait parameter in normal overground walking, has not been studied, yet. We aim to analyse the effects of auditory cues on the variability of foot clearance versus the variability of othe...

The control of minimum toe clearance (MTC, as quantified with its stride-to-stride variability during walking) is a promising marker to evaluate motor control. The control of MTC, compared to other gait parameters, was reported to have higher priority. The relationship between the control of MTC and other gait parameters should be examined to eluci...

Fatigue directly affects key features of the sensorimotor system which disorganizes voluntary control of movement accuracy. Local dynamic stability of walking is considered a sensitive measure for neuromuscular performance. To gain greater insight in the role of fatigue in motor behaviour in older and young adults during walking, the current experi...

Background Considering that proprioceptive deficits seem to be responsible for functional ankle instability, the precise control of ankle angles during running may be impaired. Thus, the aim of the study was to evaluate the influence of functional ankle instability on intra-individual variability of ankle kinematics during running. Methods Lower ex...

Gait variability is an important measure in clinical settings to diagnose older individuals with fall risk. This study examines whether a familiarization trial improves test-retest reliability of gait variability. Twenty-two older participants walked twice at 1 day and twice 7 days later. The standard deviations of stride length, swing time, stance...

In the recent years, local dynamic stability of walking was frequently used to quantify motor control. Particularly, dual-task paradigms are used to assess a shift in gait control strategy to test walking in real life situations. Texting short messages while walking is a common motor-cognitive dual task of daily living. To able to monitor possible...

Background Extreme levels of gait variability and local dynamic stability of walking are associated with risk of falling and reduced executive functions. However, it is not sufficiently investigated how gait variability and local dynamic stability of human walking develop in the course of a motor-cognitive intervention. As dancing implies high dema...

Local dynamic stability is a critical aspect of stable gait but its assessment for use in clinical settings has not yet been sufficiently evaluated, particularly with respect to inertial sensors applied on the feet and/or trunk. Furthermore, key questions remain as to which state-space reconstruction is most reliable and valid. In this study, we ev...

Research Question: Does gait control change when stride times are externally constrained by auditory cues and does an additional cognitive load given to young and older individuals influence this potential effect? Introduction: Movement variability does not always interfere with task performance. Hence, controlling movement variability which does n...

Increased gait variability is common in chronic low back pain patients, which is a sign of their diminished proprioceptive feedback. When proprioceptive information is reduced, vision partly takes over the role of proprioception. Therefore, a loss of visual feedback would have a more negative effect in individuals with diminished proprioception. To...

This systematic review provides an overview of the literature deducing information about brain activation during 1) imagined walking using MRI/fMRI or 2) during real walking using measurement systems as fNIRS, EEG and PET. Three independent reviewers undertook an electronic database research browsing six databases. The search request consisted of t...

Augmented feedback is frequently used in gait training to efficiently correct specific gait patterns in patients with different disorders. The patients use this external augmented feedback to align actual movements in a way that predefined gait characteristics can be achieved. Voluntary changes of gait characteristics are reported to reduce local d...

Introduction/Background: Pain and extreme levels of gait variability in dual-task situations are associated with higher fall risk. Pain, however, is a fall risk factor which seems to be continually disregarded [1, 2]. A possible cause explaining why pain increases fall risk in an everyday dual-task situation might be that pain interferes with execu...

Background: Extreme levels of gait variability are associated with fall risk (Hamacher et al., 2011) and reduced executive function. As walking demands cognitive effort, gait variability is affected when subjects perform a dual task. It is not verified if dual-task walking improves after a cognitive-motor intervention. Dancing implies high demands...

Dancing is a complex sensorimotor activity involving physical and mental elements which have positive effects on cognitive functions and motor control. The present randomized controlled trial aims to analyze the effects of a dancing program on the performance on a motor-cognitive dual task. Data of 35 older adults, who were assigned to a dancing gr...

Objective Gait variability is frequently used to identify rehabilitation progresses in orthopedic and neurologic diseases by means of repeated testing. However, learning effects are a significant issue. This study examined if the inter-day reliability of gait variability parameters improves with an additional familiarization trial. Design Within a...

Chronic pain and gait variability in a dual-task situation are both associated with higher risk of falling. Executive functions regulate (dual-task) gait variability. A possible cause explaining why chronic pain increases risk of falling in an everyday dual-task situation might be that pain interferes with executive functions and results in a dimin...

While camera-based motion tracking systems are considered to be the gold standard for kinematic analysis, these systems are not practical in clinical practice. However, the collection of gait parameters using inertial sensors is feasible in clinical settings and less expensive, but suffers from drift error that excludes accurate analyses. The goal...

Due to total hip replacement (THR), patients reveal abnormal gait patterns which post-operative do often not return to "normal". The restoration towards normal gait reduces stress on the adjacent joints which consequently reduces risk of osteoarthrosis development. Motor-performance is related to the structure of the movement in long-term memory, t...

Head-mounted displays (HMDs) virtually augment the visual world to aid visual task completion. Three types of HMDs were compared [look around (LA); optical see-through with organic light emitting diodes and virtual retinal display] to determine whether LA, leaving the observer functionally monocular, is inferior. Response times and error rates were...

Abnormal gait pattern of the frontal plane (i.e. Duchenne gait and Trendelenburg gait) may be caused by a variety of diseases. The aim of this pilot study was to evaluate the instantaneous effect of a visual feedback system on frontal plane pelvis and trunk movements in order to use it in patients with THR in subsequent studies. A total of 24 women...

Aim: Because of the increasing complexity of industrial work processes, the use of so-called virtual reality technical support is becoming more common. Mobile augmented reality (MAR) offers work assistance solutions for complex manual production processes in a variety of fields of application. In such processes, appropriate information is projected...

The potential of Augmented Reality (AR) to support industrial processes has been demonstrated in several studies. While there have been first investigations on user related issues in the long-duration use of mobile AR systems, to date the impact of theses systems on physiological and psychological aspects is not explored extensively. We conducted a...

Analysis of heart rate variability (HRV) is increasingly being used in sports medicine and sports science. However different measuring systems as well as different analytical methods have been applied, making it difficult to compare study results. Therefore we aimed at comparing the MT-101-Holter-ECG (Schiller / Baar) with the newest mobile heart...

Analysis of heart rate variability (HRV) is increasingly being used in sports medicine and sports science. However different measuring systems as well as different analytical methods have been applied, making it difficult to compare study results. Therefore we aimed at comparing the MT-101-Holter-ECG (Schiller/Baar) with the newest mobile heart fre...

In this paper we report on our ongoing studies around the application of augmented reality methods to support the order picking process of logistics applications. Order picking is the gathering of goods out of a prepared range of items following some customer orders. We named the visual support of this order picking process using head-mounted displ...