Klaus Mattes

A sound design for acoustic feedback in elite sports

Sound (acoustic information) is the naturally evocative, audible result of kinetic events. Humans interact with the world by the everyday experience of listening to perceive and interpret the environment. Elite athletes, especially, rely on sport specific sounds for feedback about successful (or unsuccessful) movements. Visualization plays the dominant role in technique analysis, but the limitations of visual observation (of time related events) compared with auditory perception, which represents information with a clearer time-resolution, mean that acoustic displays offer a promising alternative to visual displays. Sonification, as acoustic representation of information, offers an abundance of applications in elite sports for monitoring, observing movement and detecting changes therein. Appropriate sound is needed to represent specific movement patterns. This article presents conceptual considerations for a sound design to fulfill the specific purpose of movement optimization that would be acceptable to elite athletes, with first practical experience with elite athletes in rowing.

Influence of a visual–verbal Stroop test on standing and walking performance of older adults

The dual task (DT) paradigm has been used to investigate decrements in balance performance while walking and standing in fall prevention studies with older adults. However, there are inconsistent findings whether balance performance decreases or increases in DT situations. Following different theoretical models (e.g. limited resource hypothesis or cross domain competition model), these inconsistent findings can be explained by task settings and task complexity. We compared DT performance in an executive control task (Stroop test) while standing and walking to analyze which theoretical model would fit our data best. Twenty-eight persons (>65 years) were examined under single task (ST) and DT conditions for standing (sway length and sway velocity) and walking (step length, step width (SW), peak forces of the heel, mid- and forefoot). SW increased from ST to DT conditions, and step length decreased significantly. Maximum forces of the forefoot were reduced whereas the maximum forces of the midfoot increased. Additionally, correct answers of the Stroop test decreased from the ST baseline condition to DT walking. No correlations were found between DT costs (performance decrements) of standing and walking. For both conditions (standing and walking), the limited resources hypothesis fits best. Moreover, not all modified gait variables could be defined as negative DT costs. Increased SW and decreased step length might be used to compensate influences on lateral stability while demands on motor-cognitive resources increase. Further, drawing conclusions from a standing task for walking conditions might lead to misinterpretations.

Effects of acoustic feedback training in elite-standard Para-Rowing.

Abstract Assessment and feedback devices have been regularly used in technique training in high-performance sports. Biomechanical analysis is mainly visually based and so can exclude athletes with visual impairments. The aim of this study was to examine the effects of auditory feedback on mean boat speed during on-water training of visually impaired athletes. The German National Para-Rowing team (six athletes, mean ± s, age 34.8 ± 10.6 years, body mass 76.5 ± 13.5 kg, stature 179.3 ± 8.6 cm) participated in the study. Kinematics included boat acceleration and distance travelled, collected with Sofirow at two intensities of training. The boat acceleration-time traces were converted online into acoustic feedback and presented via speakers during rowing (sections with and without alternately). Repeated-measures within-participant factorial ANOVA showed greater boat speed with acoustic feedback than baseline (0.08 ± 0.01 m·s−1). The time structure of rowing cycles was improved (extended time of positive acceleration). Questioning of athletes showed acoustic feedback to be a supportive training aid as it provided important functional information about the boat motion independent of vision. It gave access for visually impaired athletes to biomechanical analysis via auditory information. The concept for adaptive athletes has been successfully integrated into the preparation for the Para-Rowing World Championships and Paralympics.

Human Body Mechanics of Pushing and Pulling: Analyzing the Factors of Task-related Strain on the Musculoskeletal System

The purpose of this review is to name and describe the important factors of musculoskeletal strain originating from pushing and pulling tasks such as cart handling that are commonly found in industrial contexts. A literature database search was performed using the research platform Web of Science. For a study to be included in this review differences in measured or calculated strain had to be investigated with regard to: (1) cart weight/ load; (2) handle position and design; (3) exerted forces; (4) handling task (push and pull); or (5) task experience. Thirteen studies met the inclusion criteria and proved to be of adequate methodological quality by the standards of the Alberta Heritage Foundation for Medical Research. External load or cart weight proved to be the most influential factor of strain. The ideal handle positions ranged from hip to shoulder height and were dependent on the strain factor that was focused on as well as the handling task. Furthermore, task experience and subsequently handling technique were also key to reducing strain. Workplace settings that regularly involve pushing and pulling should be checked for potential improvements with regards to lower weight of the loaded handling device, handle design, and good practice guidelines to further reduce musculoskeletal disease prevalence.

Interactive Sonification in Rowing: Acoustic Feedback for On-Water Training

Feedback systems used in elite sport mainly provide visual information. Another approach displays information audibly via sonification to create coherency between action and reaction. This article describes the use of sonification as acoustic feedback (AF) in on-water rowing training with elite athletes. On the theoretical basis of an ecological dynamics approach, the audio-motor relationship was elucidated for understanding expertise and skill acquisition in sport. Results gained from athlete surveys between 2009 and 2013 were presented to determine if AF reflects specific sections within the rowing-motion comprehensible for the athletes and if the information is provided in a way that is useful for technique training. The final aim was to provide criteria and recommendations for the development of sonification-based applications within a moving context for sports and rehabilitation.

Effects of Dual-Task Management and Resistance Training on Gait Performance in Older Individuals: A Randomized Controlled Trial

Background: Dual-task (DT) training is a well-accepted modality for fall prevention in older adults. DT training should include task-managing strategies such as task switching or task prioritization to improve gait performance under DT conditions. Methods: We conducted a randomized controlled trial to evaluate a balance and task managing training (BDT group) in gait performance compared to a single task (ST) strength and resistance training and a control group, which received no training. A total of 78 older individuals (72.0 ± 4.9 years) participated in this study. The DT group performed task managing training incorporating balance and coordination tasks while the ST group performed resistance training only. Training consisted of 12 weekly sessions, 60 min each, for 12 weeks. We assessed the effects of ST and BDT training on walking performance under ST and DT conditions in independent living elderly adults. ST and DT walking (visual verbal Stroop task) were measured utilizing a treadmill at self-selected walking speed (mean for all groups: 4.4 ± 1 km h-1). Specific gait variables, cognitive performance, and fear of falling were compared between all groups. >Results: Training improved gait performance for step length (p < 0.001) and gait-line (ST: p < 0.01; DT p < 0.05) in both training groups. The BDT training group showed greater improvements in step length (p < 0.001) and gait-line (p < 0.01) during DT walking but did not have changes in cognitive performance. Both interventions reduced fear of falling (p < 0.05). Conclusion: Implementation of task management strategies into balance and strength training in our population revealed a promising modality to prevent falls in older individuals. Trial registration: German register of clinical trials DRKS00012382.

Reproducibility of isokinetic maximum strength in the closed chain of the lower extremities, hand and leg bilateral asymmetry

The comparison of maximal concentric strength between the affected and unaffected leg is a criterion for assessing the rehabilitation progress after unilateral injury. In healthy individuals and as a result of sport specific load (soccer) left/right leg strength differences may occur. Aim of the present study was to determine the relative and absolute reproducibility of a double legged isokinetic concentric test protocol for maximal strength (two sets of three reps in a leg press with 180 mm/s) separately measured for the left and right leg in healthy physically active men ( N = 30, age = 26.5 ± 3.5 years) by use of the ICC (3.1) and Bland Altman method. The absolute reproducibility of the average maximal strength was for the group comparison 118 N and 127 N (10.1 and 11.3 %) and for the individual comparison 231 or 249 N (20 and 22 %) for the left and right leg. Significantly higher values of the left leg were found (from 3.6 to 3.2 %). The test protocol is suitable for the diagnosis of the isokinetic maximal concentric strength considering leg asymmetries. The differences in footedness must be considered in rehabilitation after unilateral injury and for comparisons of athletes with a specific leg asymmetry.

Influence of local fatigue of the plantar flexors and dorsiflexors on plantar pressure during running at three running speeds

Muscle fatigue can affect the absorption of impact forces during running which can increase the risk for running injuries. Conflicting results exist about the change of plantar pressure (PP) maxima. The study aimed to examine the influence of a standardised fatigue protocol on PP distribution of rearfoot strike runners considering possible test effects and leg asymmetries. 30 male runners volunteered in a laboratory test with repeated-measures after familiarization on the treadmill (11-15 km/h). Isokinetic fatigue protocol included ten sets of six concentric contractions (10 s set break, ω=60°/s). The first force maximum and the peak PP for three foot-regions were tested with an analysis of variance. The plantar flexors (PF) decreased to 52%-62% and the dorsiflexors (DF) to 35-41% of the isometric maximum strength. Maximum of PP under the heel and forefoot decreased to 8.3% and 5.9%, respectively. As hypothesized, the fatigue protocol reduced the performance of DF more intensely which resulted in a muscle imbalance indicating an increased injury-risk. Because of their greater muscle mass and function, PF are more fatigue-resistant during running. The reductions in pressure values may indicate a possible protective strategy to counteract injuries during muscle fatigue. For injury prevention, a strength training of the foot muscles with focus on DF is recommended in addition to running.

Influence of acoustic feedback on boat speed and crew synchronization in elite junior rowing

Coordination and crew synchronization are essential for a smooth boat run in rowing. The aim of this study was to investigate the effects of acoustic feedback on boat speed, rowing technique, and crew synchronization in elite junior rowing. Thirty junior athletes (A, B–squad) participated in the field study in two measuring series in a total of eight boats. Measuring included handle forces, rowing angle, boat acceleration, and distance traveled at two training intensities (20, 22 strokes/minute). Also, blood lactate and heart rate were collected. Boat acceleration–time traces were sonified into online acoustic feedback and presented via speakers during rowing. A repeated measures within-participant factorial analysis of variance compared sections with and without acoustic feedback (α = 0.05). Significantly faster boat speed with acoustic feedback compared to baseline was found for both squad levels. The time structure of rowing cycles was improved (prolonged duration of positive acceleration). No differences were found for handle power and physiological data. Parameters of crew synchronization showed reduced ranges for the time during drive and recovery phase, rhythm quotient, and handle speed during the drive phase with acoustic feedback compared to baseline. Questioning of athletes showed the benefits of acoustic feedback as supportive for technique training in elite junior rowing.

The BASE-Program—A Multidimensional Approach for Health Promotion in Companies

Multidimensional assessments for conducting interventions are needed to achieve positive health effects within companies. BASE is an acronym, consisting of B = “Bedarfsbestimmung” (requirements); A = “Arbeitsplatzorganisation” (organisation of work); S = “Schulung des belastungsverträglichen Alltagshandelns” (coaching preventive behaviour at work); E = “Eigenverantwortung und Selbstwirksamkeit” (self-responsibility and self-efficacy). It is a prevention program designed to avoid and reduce work-related musculoskeletal diseases. It was developed to support prevention strategies within companies. It comprises aspects of health protection, ergonomics, exercise and self-efficacy. A comprehensive assessment will identify strain e.g., musculoskeletal discomforts due to body positions or psychological stress. Moreover, the general health status, preferences and barriers for participating in health promotion programs are evaluated. This analysis leads to practical and goal-oriented recommendations and interventions which suit the needs of companies and employees. These are executed onsite in real workplace situations and involve the introduction of first-hand experience in behavioural change. Therefore, this practical approach enhances the employees’ acceptance and self-efficacy for health promotion. This can result in long-term health promoting behaviour. This article presents the outcome and sustainability effects of BASE in three different application fields (logistic, industrial and office workers).