Doris Oriwol

Short-time lower leg ischemia reduces plantar foot sensitivity

The aim of this study was to investigate the effects of short-time blood flow occlusion on plantar foot vibration sensitivity of healthy young adults. 39 subjects (20 female; 19 male) participated in the study. Blood flow reduction was evoked with a pneumatic tourniquet, placed about 10 cm above the popliteus cavity. Vibration thresholds (200 Hz) were measured at three anatomical locations of the plantar foot (heel, first metatarsal head and hallux) in three different cuff pressure conditions: baseline (0 mmHg), low (50 mmHg) and high (150 mmHg). Each pressure condition was held for 4 min prior to vibration threshold measurements. No reperfusion time was allowed between conditions. The results show a significant increase in vibration thresholds measured at all anatomical locations in the high pressure condition (150 mmHg), whereas low pressure (50 mmHg) caused a significant threshold increase only at the hallux, compared to baseline (0 mmHg) measurements. Short-time blood flow occlusion seems to affect the afferent transmission of vibration stimuli from Vater-Pacini corpuscles, resulting in decreased plantar foot sensitivity. The present study provides an insight into initial adaptations caused by reduced blood flow in plantar foot sensitivity of healthy young adults.

Methodological issues associated with the mean value of repeated laboratory running measurements

Many studies examining the biomechanics of running are conducted in laboratories, where spatial and instrumental limitations often result in protocols containing repeated running trials. Data from these repeated trials are then usually pooled into mean values to represent the roll-over characteristic for each subject. The purpose of the present study was to analyse the minimum number of trials necessary to achieve adequate validity for these protocols. We used an empirical approach, investigating 14 subjects who performed 100 running trials in a laboratory on two test days. Ground reaction forces were recorded and standard loading variables were calculated from the time series data. The convergence of cumulated mean values was analysed to verify basic assumptions about the random characteristic of repeated measurements. Analyses of differences within sessions and the root mean square error (RMSE) for repeated measurements were used to assess the absolute reliability of the repeated trials. Depending on the variable analysed, 29–57% of the subjects’ cumulated mean values demonstrated convergence. The minimum number of trials to achieve convergence was found to be between 58 and 68. The maximum differences were found to be 33% and 38% within and between days, respectively. In conclusion, the random characteristic of repeated measurements could not be confirmed, and the mean did not serve as a valid estimator for the true value of a subject. As a consequence, we suggest exploring alternative possibilities to overcome basic methodological issues of laboratory protocols in running and to reconsider the results of many previously published studies on the biomechanics of running.

Gender and age related requirements of running shoes: a questionnaire on 4501 runners

The present results of foot circumference measurements show changes during ROP which correspond to more than one shoe size. Previous studies on static foot shape, already demonstrated the scope of objective measurements to optimize last construction by considering different foot types (Mauch et al. 2009). The precise description of change in technical measurements could provide additional information for last designers to decide about last geometry in a more objective way. These results and previously reported changes in foot structure indicate a high relevance of investigating dynamic foot behaviour. Whereas static foot measurements can only explore foot shape during a single moment, the proposed technique is suitable to describe total foot deformity during walking. Circumferences can be assessed automatically without attaching markers. Further investigation will focus on implementing the knowledge about dynamic foot behaviour in last and shoe construction. First application areas will be in children’s shoes and safety shoes.

A single gyrometer inside an instrumented running shoe allows mobile determination of gait cycle and pronation velocity during outdoor running

Excessive pronation is discussed to be a factor in the development of overuse injuries. Prolonged running has been claimed to increase pronation and pronation velocity (van Gheluwe and Madsen 1997, Derrick et al. 2002). However, this coherence is contradicted by findings of (Sterzing and Hennig 1999, Butler et al. 2007). A reason for this discrepancy might lie within the different methodical study designs used, because investigations of fatiguing effects on pronation were either bond to treadmill running, to pre-post-measurements, or were biased due to, although mobile, but unpractical goniometer measurements. A practical and reliable device for mobile pronation measurement is missing so far. A lot of research has been put into the development of devices for mobile kinematic measurements. Knee joint kinematics can be determined with high accuracy using gyrometers and accelerometers (Favre et al. 2008). For ankle kinematics during running, the use of accelerometer is highly problematic due to the massive crosstalk of the impact (Takeda et al. 2009). However, in a laboratory study we were able to demonstrate that the sole use of a gyrometer at the foot resulted in adequate pronation measurements in the frontal plane (Brauner et al. 2009). The purpose of this study was to investigate whether the use of a single gyrometer integrated directly inside the midsole of a running shoe is sufficient to detect the gait cycle and to determine maximum pronation velocity during regular outdoor running.

The position of medial dual density midsole elements in running shoes does not influence biomechanical variables

Although the concept of dual density as medial support has barely been considered in footwear biomechanics research and lacks scientific proof of functionality, it has been established as a commercially popular system to influence rearfoot motion in running shoes. The goal of this study was to analyse the influence of systematically varied positions of medial dual density midsole elements in running shoes on kinematic and kinetic running variables. Seven identical running shoes with midsole density of 52 Asker C were systematically modified by incorporating medial midsole elements with dual density of 62 Asker C. The dual density position varied from rearfoot to midfoot in six of seven shoes; one shoe remained without medial dual density midsole element. Statistical procedures included nonparametric Friedman tests and repeatability coefficients, which are recommended for use as an indicator for strength of association of measured effect in investigations. Results showed no reduction and no linear trend in the measured rearfoot motion variables across shoe conditions. Hence, the effectiveness of medial dual density applications to alter rearfoot motion variables during running remains questionable.

A simple method to detect stride intervals in continuous acceleration and gyroscope data recorded during treadmill running

Inertial measurement units (IMUs) are becoming increasingly popular to analyse walking and running gait. The data usually consist of time series of continuously sampled acceleration and gyroscope data, and stride intervals often have to be extracted from the continuous data to calculate stride-related variables. Lee, Mellifont, and Burkett (2010) describe a procedure to obtain stride interval data from a single sensor attached to the sacrum of a runner. Giandolini et al. (2014) propose a method of classifying foot-strike patterns using shoe-mounted accelerometers. However, neither study explains the actual procedure used to process the accelerometer and/or gyro data. To our knowledge, there are no studies available describing a procedure (and its validity) to automatically detect strides in continuous data from shoe/foot-mounted IMUs during running.

Validity of Single Beam Timing Lights at Different Heights

Abstract Altmann, S, Spielmann, M, Engel, FA, Neumann, R, Ringhof, S, Oriwol, D, and Haertel, S. Validity of single-beam timing lights at different heights. J Strength Cond Res 31(7): 1994–1999, 2017—The purpose of this study was to quantify the effect of different timing light heights on sprint time and the validity of measurement. Two single-beam timing gate systems were used to measure 30-m sprint time (splits at 5 and 10 m) in 15 healthy and physically active male subjects. System 1 was set up at a height of 0.64 m and system 2 at 0.25 m (initial timing light) and 1.00 m (each following timing light), respectively. Participants performed 3 valid trials. The recordings of a high-speed video camera were used as a reference. Sprint times of system 1 and system 2 differed significantly between each other and from the reference system at all distances (p < 0.001). Intraclass correlation coefficients and Pearsons r values between both timing light systems and the reference system were low to moderate at 5 and 10 m and moderate to high at 30 m. Bland and Altman analysis revealed that the agreement intervals were considerably higher for the comparison between system 1 and the reference system than for system 2 and the reference system. A valid measurement of splits at 5 and 10 m via the systems used in this study is questionable, whereas 30-m times have an acceptable validity, especially when using system 2. This study confirms the influence of methodological approaches on sprint times. Coaches and researchers should consider that results gained by single-beam timing lights at different heights are not comparable.

Comparing movement variability between outdoor vs. treadmill running across 1500 strides

ied. Some studies examined more than one complexity, thus exceeding the 19 total. ‘Other’ includes visual foottargeting and mechanically perturbed platform studies. The surface complexities within each category were diverse, with substrates varying from small-grained sand to loose rocks to fixed foam, slopes §15 and uneven surfaces created using rocks, wooden blocks, artificial grass and adjustable foot supports.

Variability analysis of laboratory running

laterally applied horizontal forces are the most damaging to the MT3 (Arangio et al. 1998). The CAB elicited a more laterally applied force than the GT. Given the similar magnitudes of applied force, the difference in angle may be important. Plantar pressure at the interaction of shoe and foot at the MT3 head was significantly higher in the CAB than the GT. It is suggested that the stiffer sole and lower contact area in the CAB contributed to this, together with the reduced ankle DF range in the CAB. The current study has demonstrated differences between standard issue footwear in biomechanical variables previously associated with stress fracture to the MT3. The importance of considering footwear design features when investigating the mechanism of this injury development has therefore been highlighted.

Movement variability in recreational outdoor running

Over the past decades, numerous studies have provided evidence for the fractal-like behaviour of spatio-temporal variables of human walking gait (e. g. Hausdorff et al., 1996). There is similar evi...