Search Results (11)

The forefoot longitudinal bending stiffness of shoe soles, measured through the widely used three-point bending test, is a key factor influencing running economy and lower-limb biomechanics. This study utilizes the finite element method to simulate three-point bending, examining the influence of different loading rates on stiffness and analyzing the impact of various plate thicknesses and forefoot curvature radii on the stiffness of plates and the ‘plate-sole’ system. The results indicate that within the same displacement range, varying the loading rates did not affect stiffness. However, increased thickness significantly enhanced both the stiffness of the plate and the ‘plate-sole’, while a larger curvature radius of the plate resulted in a modest 5–10% stiffness increase for both. To conclude, the present study provides a theoretical foundation for further exploring the mechanical properties of carbon plate configurations in footwear. Plate stiffness is affected by both thickness and curvature radius, with thickness having a greater impact. The same applies to the ‘plate-sole’. The stiffness of the ‘plate-sole’ is not a simple sum of the individual contributions from the shoe and the plate. This non-additive response emphasizes the significant role of the shoe material in altering the plate’s mechanical properties, which is an important consideration for optimizing shoe design. Full article

In recent years, advanced footwear technology (AFT) has been shown to improve performance in long-distance road running by altering biomechanics and perceived comfort. This type of footwear is now being marketed for mountain running, although its effects in such races remain unevaluated. This study aimed to examine the impact of AFT on performance, biomechanics, and perceived comfort during a simulated mountain running event. Twelve trained mountain runners participated in a 3-day experiment, with a 7-day recovery between sessions. On the first day, a maximal aerobic speed test assessed the runners’ performance levels. On the second day, participants familiarized themselves with a 5.19 km mountain circuit and comfort scale. On the third day, they completed two time trials on the same circuit, separated by 30 min of passive recovery, using conventional and AFT shoes in a randomized order. Physiological and biomechanical variables were recorded, including body mass, blood lactate, running biomechanics, vertical stiffness, shoe comfort, and rating of perceived exertion (RPE). The findings indicate that AFT does not improve performance or physiological responses during a simulated mountain race, regardless of segment (uphill, downhill, or mixed). However, AFT significantly alters running biomechanics, reducing step frequency and increasing the vertical oscillation of the center of gravity, especially in uphill and downhill sections. While overall comfort remained unchanged, specific differences were observed with AFT. Coaches and practitioners should consider these findings when using AFT in mountain running training or competition. Full article

Carbon plate running shoes (CPRSs) have gained widespread popularity among elite and amateur runners, representing one of the most substantial changes in running gear over the past decade. Compared to elite runners, however, amateurs run at lower speeds and show more diverse running styles. This is a meaningful difference as many previous studies on CPRSs focus either on highly trained male runners and higher speeds or only on a single CPRSs manufacturer. The present study aims at bridging this gap by investigating how CPRSs from four different manufacturers affect running economy in amateurs of both sexes at their individual running speeds. For this purpose, 21 trained amateur triathletes (12 men; 9 women) completed an incremental treadmill test until volitional exhaustion, yielding running speeds at ventilatory thresholds 1 (v_VT1) and 2 (v_VT2). In a second session, subjects ran five trials of 3 × 3 min (speeds of 90% v_VT1, ½ (v_VT1 + v_VT2), and 100% v_VT2), wearing one out of four different pairs of CPRSs or their own preferred non-CPRS shoes in each trial. Our results show that tested CPRS models resulted in a significant reduction in the mean energy cost of transport, compared to the non-CPRS control condition, with Cohen’s d amounting to −1.52 (p = 0.016), 2.31 (p < 0.001), 2.57 (p < 0.001), and 2.80 (p < 0.001), respectively, although effect sizes varied substantially between subjects and running speeds. In conclusion, this study provides evidence that amateur athletes may benefit from various manufacturers’ CPRS models at their typical running speeds to a similar degree as highly trained runners. It is recommended that amateur athletes evaluate a range of CPRSs and select the shoe that elicits the least subjective sensation of fatigue over a testing distance of at least 400–1000 m. Full article

Polymer foam that provides good support with high energy return (low energy loss) is desirable for sport footwear to improve running performance. Ethylene-vinyl acetate copolymer (EVA) foam is commonly used in the midsole of running shoes. However, EVA foam exhibits low mechanical properties. Conventional mineral fillers are usually employed to improve EVA’s mechanical performance, but the energy return is sacrificed. Here, we produced nanocomposite foams from EVA and multi-walled carbon nanotubes (CNT) using a chemical foaming process. Two kinds of CNT derived from the upcycling of commodity plastics were prepared through a catalytic chemical vapor deposition process and used as reinforcing and nucleating agents. Our results show that EVA foam incorporated with oxygenated CNT (O-CNT) demonstrated a more pronounced improvement of physical, mechanical, and dynamic impact response properties than acid-purified CNT (A-CNT). When CNT with weight percentage as low as 0.5 wt% was added to the nanocomposites, the physical properties, abrasion resistance, compressive strength, dynamic stiffness, and rebound performance of the EVA foams were improved significantly. Unlike the conventional EVA formulation filled with talc mineral fillers, the incorporation of CNT does not compromise the energy return of the EVA foam. From the long-cycle dynamic fatigue test, the CNT/EVA foam displays greater properties retention as compared to the talc/EVA foam. This work demonstrates a good balanced of mechanical-energy return properties of EVA nanocomposite foam with very low CNT content, which presents promising opportunities for lightweight–high rebound midsoles for running shoes. Full article

Carbon fiber insole (CFI), which is lightweight and stiff to reduce energy loss and help wearers perform better in sports, has recently been introduced. However, reports are scarce on the effects of CFI on sports performance, muscle activation, and wearing comfort. This study investigated the acute effects of CFI on sports performance, lower extremity muscle activity, and subjective comfort. Thirty young healthy males with shoe sizes between 260 and 270 mm performed various sports tasks (power generation, agility, and speed) and treadmill runs with wearable sensors under two experimental insole conditions (benchmark insole as a baseline, CFI). The results showed that, compared to the benchmark insole, CFI significantly improved sports performance in terms of power generation (~1.5%) and agility (~1%). However, it activated more of the Tibialis Anterior (~0.7%) and Gastrocnemius Medialis (~0.8%) muscles, and was perceived to be stiffer and less comfortable. These findings suggested that CFI could improve sports performance, but could cause more lower extremity muscle activation and subjective discomfort. Full article

Although various sports footwear demonstrated marked changes in running biomechanical variables, few studies have yielded definitive findings on the underlying mechanisms of shoe constructions affecting running-related performance and injuries. Therefore, this study focused on examining the effect of basic shoe constructions on running biomechanics and assessing the current state of sports shoe production in terms of injury and efficiency. Relevant literature was searched on five databases using Boolean logic operation and then screened by eligibility criteria. A total of 1260 related articles were retrieved in this review, and 41 articles that met the requirements were finally included, mainly covering the influence of midsole, longitudinal bending stiffness, heel-toe drop, shoe mass, heel flare, and heel stabilizer on running-related performance and injuries. The results of this review study were: (1) The functional positioning of running shoe design and the target groups tend to influence running performance and injury risk; (2) Thickness of 15–20 mm, hardness of Asker C50-C55 of the midsole, the design of the medial or lateral heel flares of 15°, the curved carbon plate, and the 3D printed heel cup may be beneficial to optimize performance and reduce running-related injuries; (3) The update of research and development concepts in sports biomechanics may further contribute to the development of running shoes; (4) Footwear design and optimization should also consider the influences of runners’ strike patterns. Full article

Footwear properties can influence physiological and biomechanical variables, which may lead to positive changes in distance running performance. One innovative development in running shoe technology is adding carbon fiber plates to increase midsole bending stiffness. However, there are only a few studies investigating the influence of shoe conditions on both physiological and biomechanical variables, simultaneously, when running for longer than 5 min or for distances > 1 km. Hence, the purpose of the current study was to investigate the influence of different running shoe concepts with carbon fiber plates on physiological and biomechanical parameters during a 10 km treadmill run. Twenty-three athletes participated in the study, which comprised four measurement days for each subject. On the first day, subjects performed a treadmill exhaustion test to determine maximum oxygen uptake. On the second, third, and fourth days, each subject ran 10 km at 70% of their maximum oxygen uptake in one of three shoe models. Significant differences were found between the shoe conditions for the biomechanical parameters, but not for the physiological parameters. It seems that runners adjusted their running styles to the shoe conditions during the 10 km run to reduce the load on the lower extremities without compromising their endurance performance. These results may have practical implications for runners, coaches, and shoe manufacturers. Full article

The introduction of carbon fiber plate shoes has triggered a plethora of world records in running, which has encouraged shoe industries to produce novel shoe designs to enhance running performance, including shoes containing conductor elements or “grounding shoes” (GS), which could potentially reduce the energy cost of running. The aim of this study was to examine the physiological and perceptual responses of athletes subjected to grounding shoes during running. Ten elite runners were recruited. Firstly, the athletes performed an incremental running test for VO₂max and anaerobic threshold (AT) determination, and were familiarized with the two shoe conditions (traditional training shoe (TTS) and GS, the latter containing a conductor element under the insole). One week apart, athletes performed running economy tests (20 min run at 80% of the AT) on a 400 m dirt track, with shoe conditions randomized. VO₂, heart rate, lactate, and perceived fatigue were registered throughout the experiment. No differences in any of the physiological or perceptual variables were identified between shoe conditions, with an equal running economy in both TTS and GS (51.1 ± 4.2 vs. 50.9 ± 5.1 mL kg⁻¹ min⁻¹, respectively). Our results suggest that a grounding stimulus does not improve the energy cost of running, or the physiological/perceptual responses of elite athletes. Full article

In this paper, to investigate the independent effect of the construction of the forefoot carbon-fiber plate inserted to the midsole on running biomechanics and finite element simulation, fifteen male marathon runners were arranged to run across a runway with embedded force plates at two specific running speeds (fast-speed: 4.81 ± 0.32 m/s, slow-speed: 3.97 ± 0.19 m/s) with two different experimental shoes (a segmented forefoot plate construction (SFC), and a full forefoot plate construction (FFC)), simulating the different pressure distributions, energy return, and stiffness during bending in the forefoot region between the SFC and FFC inserted to midsole. Kinetics and joint mechanics were analyzed. The results showed that the footwear with SFC significantly increased the peak metatarsophalangeal joint (MTPJ) plantarflexion velocity and positive work at the knee joint compared to the footwear with FFC. The results about finite element simulation showed a reduced maximum pressure on the midsole; meanwhile, not significantly affected was the longitudinal bending stiffness and energy return with the SFC compared to the FFC. The results can be used for the design of marathon running shoes, because changing the full carbon fiber plate to segment carbon fiber plate induced some biomechanical transformation but did not significantly affect the running performance, what is more, reducing the peak pressure of the carbon plate to the midsole by cutting the forefoot area of the carbon fiber plate could be beneficial from a long-distance running perspective for manufacturers. Full article

Marathon running leaves a significant carbon footprint regarding CO₂ emissions; for example, 37 percent of New York Marathon participants travel internationally to New York. The aim of this study is to estimate the CO₂ footprint of a person training and competing in a marathon; we will also propose methods to minimize the CO₂ footprint because of transportation. In addition, we also examine the influence of food practices and hygiene on training and racing a marathon. Methods: We estimated the annual carbon footprint of one person taking part in a marathon. We considered all training, racing, and travelling (local and international) for one person (we are going to give him the first name of “Henri”), and then compared his CO₂ footprint with his colleagues playing tennis and soccer. The excess CO₂ footprint whilst running and for shoes, clothing, books, magazines, insurance, travel, hygiene, laundry, and resources for electronics and additional food consumed were calculated. For competitions, we estimated and compared the CO₂ emission from transportation to national vs. international marathon (New York). Results: We estimated that our runner emitted 4.3 tons of CO₂ equivalent (CO₂e), including all greenhouse gases. A transatlantic flight to New York corresponded to 3.5 tons CO₂, which is 83% of the annual carbon footprint of an average French citizen which is about 11 tons CO₂e/year. This leads to a sudden 40% increase in Henri’s annual carbon footprint. Conclusions: By focusing on the additional carbon footprint from one year of marathon training and racing, and traveling locally versus internationally, this sport still has a potentially significant carbon footprint that runners and race organizers ought to consider. We wanted to answer a growing question of marathon runners who are wondering about the carbon footprint of their sports practice in following with a new environmentalist trend that considers not traveling anymore to participate in marathons and to stay local. However, the representativeness in the selection of calculation objectives is very low. There is no need for statistics since this study is a theoretical simulation of traditional training and competition practices of marathon runners. Full article

Porous polymer dielectric materials have been developed to increase the sensitivity of capacitive pressure sensors, so that they might expand capacitive sensor use, and promote the realization of the advantages of this class of sensor in further fields. However, their use has not been demonstrated in physiological monitoring applications such as respiration monitoring and body position detection during sleep; an area in need of unmet medical attention for conditions such as sleep apnea. Here, we develop and characterize a sensor comprised of a poly dimethylsiloxane (PDMS) sponge dielectric layer, and PDMS/carbon black (CB) blend electrode layers, with suitable compliance and sensitivity for integration in mattresses, pillows, and athletic shoe insoles. With relatively high pressure sensitivity (~0.1 kPa⁻¹) and mechanical robustness, this sensor was able to fulfill a wide variety of roles, including athletic monitoring in an impact mechanics scenario, by recording heel pressure during running and walking, and physiological monitoring, by detecting head position and respiration of a subject lying on a pad and pillow. The sensor detected considerably greater relative signal changes than those reported in recent capacitive sensor studies for heel pressure, and for a comparably minimal, resistive sensor during respiration, in line with its enhanced sensitivity. Full article