Biology subjects

Bertschy, M.

Publications and source records attributed to Bertschy, M..

6 recordsLinked to original sources

bioRxiv2025

Data driven shoe design improves running economy beyond state-of-the-art Advanced Footwear Technology running shoes

Advanced Footwear Technology (AFT) has enabled remarkable improvements in running performance over traditional marathon racing shoes. However, reported differences between state-of-the-art AFT models are small, and vary across individuals. To assess if the benefits of AFT have been fully realized or if further running economy improvements can be unlocked using modern computational design and optimization techniques, we compared a prototype AFT shoe developed using a data-driven computational design process (PUMA Fast-R 3; FR3) against state-of-the-art AFT models. We quantified running economy for 15 trained runners (11M, 4F) in this prototype AFT shoe and three commercially available AFT models: the PUMA Fast-R 2 (FR2), the Nike Alphafly 3 (NIKE), and the Adidas Adios Pro Evo (ADI). Running economy in the FR3 was 3.15 {+/-} 1.24%, 3.62 {+/-} 1.25%, and 3.54 {+/-} 1.16% better than in the FR2, NIKE and ADI (all p < 0.001), respectively, and every individual performed best in the FR3 shoes. While step parameters were similar between FR3 and FR2, the FR3 had a lower step frequency than the ADI (p = 0.013) and longer contact time than the NIKE and ADI (both p<0.001). Our results suggest that computational design analysis is a promising frontier in performance running shoe design, offering potential for further improvements and personalized AFT models.

physiology↗

bioRxiv2025

Is increasing the effective leg length of a human runner metabolically beneficial?

The purpose of this study was to understand if footwear midsole thickness can decrease the metabolic cost of running by increasing the effective leg length of a runner. We also sought to understand the role of midsole compliance on these measures. Participants (n = 16) ran on a treadmill at 14 km h-1 in four mass-matched shoe conditions: 30, 40, and 60 mm thickness of a firm midsole foam and 60 mm thickness of a compliant midsole foam. Over two testing sessions, we measured metabolic cost (two 5-minute trials in each condition) and biomechanical measures (one 2-minute trial in each condition). Increasing thickness in the firm midsole conditions increased effective leg length during early, mid, and late stance (all p < 0.001). However, metabolic cost increased (p = 0.031). Changing material from firm to compliant decreased effective leg length during midstance (p < 0.001), but not during early or late stance, and decreased metabolic cost (p < 0.001). Results suggest that increasing midsole thickness can increase the effective leg length of a runner, but this isolated effect leads to increasing in metabolic cost. On the other hand, increasing midsole compliance leads to reductions in metabolic cost, agreeing with previous literature. We suggest that the performance benefits seen in advanced footwear technology with increased midsole thickness are likely due to increased capacity to return mechanical energy, not due increases in effective leg length. Summary StatementIncreased midsole compliance, not increased effective leg length, is responsible for decreased metabolic cost in running.

physiology↗

bioRxiv2024

Effects of longitudinal bending stiffness and midsole foam on running energetics

BackgroundAdvanced footwear technology has become commonplace in the competitive running world. However, a systematic exploration of the effects of each of the primary components has not yet been presented. PurposeTo quantify running economy and step parameters in four different shoe conditions: PEBA shoes with plate, PEBA shoes without plate, EVA shoes with plate and EVA shoes without plate. MethodsParticipants ran at 14 km/h (n = 8 males) or 12 km/h (n = 6 females) on a treadmill. The shoe order was randomly assigned for the four shoe conditions, where the participants wore each shoe twice in a mirrored order. ResultsThere was a significant reduction in metabolic power (1.0%) associated with the presence of a plate, as well as a similar reduction based on foam type (1.0%). However, there was no significant interaction between presence of plate and foam type. Adding a plate significantly reduced metabolic power for EVA by 1.3% but not for PEBA. PEBA foam significantly reduced metabolic power by 1.3% in shoes without a plate, but not for the shoes with a plate. Step frequency and contact time were similar between shoes and not correlated to running economy improvements. ConclusionsStarting from a baseline condition with traditional foam without a plate, either adding a plate or using PEBA foam improved running economy with a similar amount (1.3%). Adding the alternate second feature non-significantly improved running economy with an additional 0.6%. The benefit of both technologies combined (1.9%) was smaller than the sum of its parts (1.3% each). Key pointsO_LIThe use of a PEBA foam midsole or the addition of a carbon fiber plate improves running economy a similar amount when compared to a traditional EVA running shoe without a plate. C_LIO_LIContrary to our hypothesis, the benefit of both technologies combined (1.9%) was smaller than the sum of its parts (1.3% each). C_LI

physiology↗

bioRxiv2023

Quantifying the performance benefits of middle distance running super spikes

BackgroundQuantifying the potential benefits of advanced footwear technology (AFT) track shoes (i.e., "spikes") in middle-distance events is challenging, because repeated maximal effort trials (as in sprinting) or aerobic running economy trials (as in long-distance running) are not feasible. MethodsWe introduce a novel approach to assess the benefits of AFT spikes, consisting of a series of 200 m runs at self-perceived middle-distance race pace with 10 min recovery and conducted four experiments to evaluate its validity, sensitivity, reproducibility, and utility. ResultsIn experiment 1, participants ran 1.2% slower in spikes with 200 g added mass vs. control spikes, exactly equal to the known effects of shoe mass on running performance. In experiment 2, participants ran significantly faster in AFT prototype spikes vs. traditional spikes. In experiment 3, we compared two other AFT prototype spikes against traditional spikes, on three separate days. Group-level results were consistent across days, but our data indicates that at least two separate sessions are needed to evaluate individual responses. In experiment 4, participants ran significantly faster in two AFT spike models vs. traditional spikes (2.1% and 1.6%). Speed was similar between a third AFT spike model and the traditional spikes. These speed results were mirrored by changes in step length, as participants took significantly longer steps in the two faster AFT spike models (2.3% and 1.9%), while step length was similar between the other spikes. ConclusionOur novel, interval-based approach is a valid and reliable method to quantify differences between spikes at middle-distance running intensity.

physiology↗

bioRxiv2022

Reconstruction and simulation of thalamoreticular microcircuitry

Thalamoreticular circuitry is known to play a key role in attention, cognition and the generation of sleep spindles, and is implicated in numerous brain disorders, but the cellular and synaptic mechanisms remain intractable. Therefore, we developed the first detailed computational model of mouse thalamus and thalamic reticular nucleus microcircuitry that captures morphological and biophysical properties of [~]14,000 neurons connected via [~]6M synapses, and recreates biological synaptic and gap junction connectivity. Simulations recapitulate multiple independent network-level experimental findings across different brain states, providing a novel unifying cellular and synaptic account of spontaneous and evoked activity in both wakefulness and sleep. Furthermore, we found that: 1.) inhibitory rebound produces frequency-selective enhancement of thalamic responses during wakefulness, in addition to its role in spindle generation; 2.) thalamic interactions generate the characteristic waxing and waning of spindle oscillations; and 3.) changes in thalamic excitability (e.g. due to neuromodulation) control spindle frequency and occurrence. The model is openly available and provides a new tool to interpret spindle oscillations and test hypotheses of thalamoreticular circuit function and dysfunction across different network states in health and disease.

neuroscience↗

bioRxiv2022

The psychotomimetic ketamine disrupts the transfer of late sensory information in the corticothalamic network

In prodromal and early schizophrenia, disorders of attention and perception are associated with structural and chemical brain abnormalities, and with dysfunctional corticothalamic networks exhibiting disturbed brain rhythms. The underlying mechanisms are elusive. The non-competitive NMDA receptor antagonist ketamine simulates the symptoms of prodromal and early schizophrenia, including disturbances in ongoing and task & sensory-related broadband beta-/gamma-frequency (17-29 Hz/30-80 Hz) oscillations in corticothalamic networks. In normal healthy subjects and rodents, complex integration processes, like sensory perception, induce transient, large-scale synchronized beta/gamma oscillations in a time window of a few hundreds of ms (200-700 ms) after the presentation of the object of attention (e.g., sensory stimulation). Our goal was to use an electrophysiological multisite network approach to investigate, in lightly anesthetized rats, the effects of a single psychotomimetic dose (2.5 mg/kg, subcutaneous) of ketamine on sensory stimulus-induced oscillations. Ketamine transiently increased the power of baseline beta/gamma oscillations and decreased sensory-induced beta/gamma oscillations. In addition, it disrupted information transferability in both the somatosensory thalamus and the related cortex and decreased the sensory-induced thalamocortical connectivity in the broadband gamma range. In conclusion, the present findings support the hypothesis that NMDA receptor antagonism disrupts the transfer of perceptual information in the somatosensory cortico-thalamo-cortical system. LAY ABSTRACTCognitive deficit is usual in schizophrenia. Perception- or task-related beta/gamma-frequency oscillations are decreased. In healthy humans and rodents, ketamine-induced NMDA receptor antagonism simulates the symptoms of early schizophrenia and excessively amplifies baseline beta/gamma oscillations. In the present study, using an electrophysiological multisite network approach in a rodent model, it is demonstrated that ketamine, systemically administered at a single psychotomimetic dose, increases baseline beta/gamma oscillations, decreases beta/gamma responses induced by sensory stimulation in a short time window (200-700 ms), and disrupts information transfer in the cortico-thalamo-cortical network. The present findings have mechanistic relevance for cognitive deficits in schizophrenia.

neuroscience↗