It has been proposed, that ‘the better running economy and personal best time obtained with the VP4 [Vaporfly 4% or similar advanced shoe constructions] cannot be currently explained from a [functi...

Footwear energy storage and return is often suggested as one explanation for metabolic energy savings when running in Advanced Athletic Footwear. However, there is no common understanding of how footwear energy storage and return facilitates changes in muscle and joint kinetics. The purpose of this study was to evaluate the magnitude and timing of foot, footwear and lower limb joint powers and work while running in Advanced and Traditional Athletic Footwear. Fifteen runners participated in an overground motion analysis study. Since footwear kinetics are methodologically challenging to quantify, we leveraged distal rearfoot power analyses ('foot + footwear' power) and evaluated changes in the magnitude and timing of foot + footwear power and lower limb joint powers. Running in Advanced Footwear resulted in greater foot + footwear work, compared to Traditional Shoes, and lower positive ankle work, potentially reducing the muscular demand on the runner. The timing of foot + footwear power varied only slightly across footwear. There are exciting innovation opportunities to manipulate the timing of footwear energy and return. This study demonstrates the research value of quantifying time-series foot + footwear power, and points industry developers towards footwear innovation opportunities.

Journal of Medical Internet Research - International Scientific Journal for Medical Research, Information and Communication on the Internet #Preprint #PeerReviewMe: Warning: This is a unreviewed preprint. Readers are warned that the document has not been peer-reviewed by expert/patient reviewers or an academic editor, may contain misleading claims, and is likely to undergo changes before final publication, if accepted, or may have been rejected/withdrawn. Readers with interest and expertise are encouraged to sign up as peer-reviewer, if the paper is within an open peer-review period. Please cite this preprint only for review purposes or for grant applications and CVs (if you are the author). Background: Diabetic foot ulcers (DFUs) are a life-changing complication of diabetes. There is increasing evidence that plantar temperature monitoring can reduce the incidence and recurrence of DFUs. Once daily foot temperature monitoring is the current guideline for identifying early signs of foot inflammation and DFUs. However, single readings of physiological signals are known to increase the risk of misdiagnosis when there are fluctuations of the signal throughout the day. Objective: The purpose of this study was to evaluate whether intra-day temperature asymmetry signals were stable or varied as a function of time in individuals at risk of DFU. Methods: Sixty-four participants with diabetes (mean age = 68 ± 13.8 years) were provided with multi-modal sensory insoles (Orpyx® Sensory Insoles) to monitor continuous temperature data at five plantar locations with a frequency of once/minute during a 90-day study window. 1,080 data days, 5400 contralateral temperature asymmetry signals, were included. The Augmented Dickey-Fuller test was used to determine whether the temperature asymmetry signals were stationary (stable) or non-stationary (time-varying). Results: The majority (82%) of temperature asymmetry signals were time-varying, with intra-day fluctuations potentially driven by physiological and environmental factors. Nearly half (44%) of time-varying signals included a mix of concerning (>2.2°C) and non-concerning (≤2.2°C) measurements, indicating the limitations of single measurements in reliably identifying DFU risk. Statistical analysis revealed significant variability in stable versus time-varying patterns both within and across participants. Notably, days with time-varying signals and concerning asymmetry measurements showed dispersion of concerning periods across participants, time windows and days, rather than consistent daily patterns. Conclusions: Continuous monitoring could provide deeper insights into plantar temperature dynamics, uncovering associations with individual-specific factors such as vascular status, historical ulcer locations, activity, gait, and foot anatomy. These findings support the need for personalized monitoring protocols and leveraging continuous data to better inform clinical decision-making.

Over the past decade, running shoes have undergone substantial innovation with the emergence of Advanced Footwear Technology (AFT). Shoes with AFT are typically characterized by highly compliant (deformable) and resilient (high energy return) midsole foams, embedded curved stiffening elements, low mass, and a rockered longitudinal geometry. This expert statement aims to synthesize established knowledge, remaining uncertainties and key directions for future research on AFT in middle‐ and long‐distance running. Current literature demonstrates robust improvements in running economy and performance with AFT, with reported metabolic savings of approximately 2%–4%, and corresponding performance improvements of 1%–3%. These benefits likely arise from a combination of “acute” and possibly “long‐term” mechanisms. Proposed acute mechanisms include decreased muscle force production due to higher positive work from energy‐returning foams, lower muscle force production to accommodate mechanical running demands due to compliant midsoles, and improved mechanical efficiency associated with greater longitudinal bending stiffness and curved geometry. Importantly, AFT features have a synergistic effect, with the relative importance of each mechanism differing depending on the context. Emerging evidence also suggests potential reductions in muscle damage/inflammation and soreness, which could support better physiological resilience, and higher training volumes/quality. From a biomechanical injury risk perspective, AFT can redistribute loading, potentially increasing metatarsal and tarsal stress while reducing tibia and possibly Achilles tendon loading. However, injury risk associated with AFT use remains equivocal, with limited high‐quality data. Notably, substantial inter‐individual variability has been observed, influencing both running economy and potential injury risk although the determinants of this variability remain unclear.