Competitive and recreational cyclists use stiff-soled shoes that firmly attach to ‘clipless’ pedals. When compared to very flexible running shoes, very stiff cycling shoes with clipless pedals enhance power output during sprint cycling. However, a recent study showed no difference in power output or sprint performance between commercially available cycling shoes that span a range of longitudinal bending stiffnesses (∼200 to 500 N·m/rad). Thus, we sought to identify the likely range of sole stiffnesses below 200 N·m/rad over which reduced cycling shoe sole stiffness begins to decrease maximal power output. We measured the mechanical power outputs of 25 road cyclists during maximal sprints wearing shoes with identical uppers but with three different sole stiffnesses. Each participant completed nine 50 m sprints (three trials for each shoe) on a road with a steady, uphill grade of 9.1%. The three shoe sole conditions were: injected nylon (longitudinal bending stiffness 194 N·m/rad), moderate stiffness thermoplastic polyurethane (medium TPU) (43 N·m/rad), and low stiffness TPU (soft TPU) (9 N·m/rad) all ridden with the same clipless pedals. Stiffness was quantified using a simple testing apparatus. Power output decreased below the sole stiffness of ∼200 N·m/rad but only moderately. Maximal 1 s crank power (Pmax1) decreased −3.1% (ES = −0.59, p = 0.020) from Nylon to medium TPU and then further decreased −2.4% (ES 16 = −0.50, p = 0.054) from medium TPU to soft TPU. Interpolating our results suggests just a ∼1% loss in Pmax1 at a sole stiffness of 100 N·m/rad. Within reasonable limits, cycling shoe sole stiffness has only a small effect on power output.

The metabolic benefits of non-rearfoot strike (non-RFS) running remain unknown because no interventions can alter the runner’s foot strike patterns involuntarily. This study investigated whether wearing running shoes that elicit involuntary non-RFS running alters the oxygen consumption (VO2) of habitual RFS and non-RFS runners. Twenty-three male runners (10 RFS and 13 non-RFS) performed six bouts of 5-min treadmill runs at slow or fast speeds below lactate thresholds. The first three bouts were performed using either the control shoes (traditional racing shoes), the shoes that elicit involuntary non-RFS (Wave Duel Pro [WDP]), or the additional shoe used for a different purpose. Subsequently, participants ran another three bouts wearing each shoe in mirror order. Only the control and WDP shoes were analysed in this study. All participants were non-RFS runners when wearing WDP. The VO2 did not differ between WDP and control in habitual non-RFS runners (43.7 ± 5.6 and 43.5 ± 5.6 mL kg−1 min−1, respectively, P = 0.306 for the main effect of shoes). A small attenuation of VO2 by approximately 0.9% was observed with WDP compared with control in habitual RFS runners (43.9 ± 5.4 and 44.3 ± 5.6 mL kg−1 min−1, respectively, P = 0.025 for the main effect of shoes). The blood lactate concentration did not differ between WDP and control in both groups (P ≥ 0.603). Similarly, the heart rate did not differ between the shoes in both groups (P ≥ 0.166). The involuntary induction of non-RFS running by changing shoes has a negligible effect on reducing the running economy of habitual RFS runners.

Spatiotemporal parameters, such as speed, cadence, stride length are often adjusted to enhance stability during walking. Minimal shoes and insoles are known to impact dynamic stability, however their combined effect on such gait parameters in healthy young adults remains unexplored. This cross-sectional study assessed the effects of a minimal shoes, the combination of a minimal shoes with a textured insoles, a minimal shoes with a supportive insoles, barefoot walking and habitual shoes on stability-related spatiotemporal walking gait parameters. Sixty-two healthy young adults (41 males and 21 females, age: 24.6 ± 5.5 years, height: 1.73 ± 0.01 m, weight: 73.8 ± 14.2 kg) were assessed using a 2-minute walk test (2-MWT), and a Timed up and Go (TUG) test in a randomized order of five different footwear conditions. Measurements were made using Kinesis GaitTM and QTUGTM sensors. Repeated measures analyses of covariance were conducted to examine the effect of footwear with gender and BMI as covariates. Results revealed improvement in observed gait parameters during the 2-MWT in minimal shoes, minimal shoes with a textured insoles and minimal shoes with a supportive insoles compared to barefoot and habitual footwear. Participants covered a significantly greater distance (p < 0.05) during the 2-MWT at a self-selected speed in all three minimal shoes conditions with larger stride length and improved cadence. Significant variations (p < 0.05) were found between barefoot walking and minimal shoes conditions while participants being least stable during the barefoot walking. The use of textured or supportive insoles within the minimal shoes did not provide any additional benefits nor did it have any detrimental effect on the spatiotemporal parameters. Nevertheless, minimal shoes with or without insoles have the potential to enhance stability during walking as speed, cadence, and stride length are improved.

Tripping often results in injury, especially in occupational settings, leading to both loss in production and increased medical expenses. Trips may occur over small perturbations, as low as 5 mm, making it almost impossible to provide effective safety precautions in many occupational settings. This explorative study evaluated the mechanical effects of collisions applied to three novel trip-reducing elements placed on the tip of a safety shoe. The assessment was conducted using a new mechanical free-body collision test, to analyse how the braking forces were affected by the trip-reducing elements. The elements tested showed a decrease of up to 83% in peak braking force and 89% in braking impulse suggesting a possible reduction in the risk of fall after tripping. Still, in-vivo studies are warranted to test if such trip-reducing elements can minimise the risk of falls in settings mimicking real life.

Advanced Footwear Technologies (AFTs) have enhanced running economy in the laboratory and improved performance in long distance events. Their resilient midsoles have renewed interest in ‘energy return’, the idea that elasticity in shoe soles could benefit athletic performance. This paper examines the concept of energy return, it’s definition, measurement and interpretation. ‘Energy return’ itself is a misnomer. Running shoe cushioning is entropically elastic, not energetically elastic and a net dissipator of energy. The term is easily confused with ‘rebound’ and ‘coefficient of restitution’, but neither are equivalent. Energy return is not a material property but a nonlinear, system dynamic outcome that depends on inertia, initial conditions, geometry, pre-test conditioning and other factors. Consequently, measurements are sensitive to test protocol variations. Results from quasi-static compression tests and standard impact tests of identical ethylene vinyl acetate foam specimens give different results. Impact tests of 180 running shoe models reveal that energy return overestimates rebound height by 57%, on average. The difference is due to the potential energy deficit (Edef ) created as the shoe sole is compressed, which accounts for 25–45% of total energy output. AFT shoes reduce energy expenditure by exploiting the known effects of shoe weight, cushioning and bending stiffness. The magnitude of energy return is small and differences among shoes even smaller. Any direct effects of ‘energy return’ on running economy remain unknown. Low density AFT foams store less energy per unit volume than conventional materials. They must be thicker and more compressible to accommodate the same input loads. Regardless of any effects on running economy, the higher energy return of AFT shoes is a necessary compensation for their inherently greater energy deficit.

Studies on advanced footwear technology (AFT) often investigate potential performance benefits for constraint populations, and high running speeds. This research compared running biomechanics, running economy and perception between males and females, when wearing three different AFT conditions at recreational running speeds. An innovation shoe sample (IM) at confirmation stage in the product creation process was compared to two commercial running shoes (MM, MF). Gender and shoe variable means were compared for main and interaction effects (p < 0.05) by a mixed 2 × 3 repeated measures analysis of variance (RM ANOVA), and effect size estimation. A main effect was seen for shoe condition, both the IM and MF showed higher vertical loading rates than MM, and higher peak vertical force 1. IM had less frontal plane rearfoot motion than both the MM and MF. At the MTPJ, IM had lower maximum dorsiflexion angle, dorsiflexion velocity leading to lower negative power and negative work than both the MM and MF. IM and MF showed significantly lower oxygen consumption than the MM. Perception measurements showed IM and MF to be significantly softer, responsive and had better propulsion than the MM. A main effect was seen for gender, females exhibited higher vertical loading rates, reduced frontal plane ankle motion and lower MTPJ motion, and lower oxygen consumption compared to males. There was no gender effect for perception. Despite biomechanical differences, both IM and MF showed improved performance compared to the MM. Males and females exhibit different biomechanics when wearing AFT, however this did not lead to differences in subjective perception. It is concluded that the specific AFT applied for IM samples in this research functions for both groups largely similarly.

The purpose of this study was to evaluate the influence of different longitudinal bending stiffnesses (LBS) on running economy and lower extremity joint biomechanics in male and female runners. Thirty participants (15 F;15M) performed a treadmill protocol of five-minute randomised aerobic runs with four different footwear conditions varying in LBS: 16.1 N/mm; 32.7 N/mm; 46.1 N/mm; 90.1 N/mm. Biomechanical data was collected at the metatarsophalangeal (MTP) and ankle joints. Running economy was quantified via oxygen consumption data. Oxygen consumption observed no significant differences between footwear conditions (p = 0.960) or significant interaction between footwear and sex (p = 0.126). Stance time observed a significant difference between footwear conditions (p < 0.001), and a significant interaction of footwear and sex (p = 0.008), increasing in females as stiffness increased. At the MTP joint, a shoe effect was present for peak bending angle (p < 0.001), peak extension (p = 0.040) and flexion (p < 0.001) angular velocity, and energy generated at the joint (p = 0.010). There was also an interaction effect of peak MTP extension angular velocity (p = 0.044), with females slightly decreasing as stiffness increased, with no reaction from males. At the ankle joint, a shoe effect was present for peak dorsiflexion (p < 0.001) and plantarflexion (p < 0.001) angular velocity, peak negative power (p < 0.001) and energy absorbed at the joint (p < 0.001). Comparing the interaction between shoe condition and male/female runners, male and female runners reacted similarly to the increased LBS with no effect on running economy and subtle changes in the stance time and MTP angular velocity for female runners. While further research is needed in this area investigating aspects related to sex-specific optimal stiffness element location and geometry, it does not appear that the stiffness magnitude has a sex dependence.

This study aimed to analyse the effects of shoes with increased longitudinal bending stiffness (LBS) on 3,000 m performance, pacing strategy, heart rate, and biomechanics in trained runners. Twelve male trained runners performed a 3,000 m time trial test in an experimental shoe with a carbon fibre plate to increase the LBS (LBS-increased) and a Control shoe (without carbon fibre plate). Running performance (total time), pacing, heart rate, and biomechanical variables were registered and analysed for each 1000 m split. An individual analysis of the responders was performed based on the smallest worthwhile change. The 3,000 m time trial performance improved by 0.74% (585.83 ± 33.39 vs. 590.17 ± 34.35 s, p < 0.001, large d = 0.829) in the LBS-increased condition compared to the Control condition with a high inter-individual variability. There were no significant differences for the split effect (p = 0.898, small ηp2 = 0.021). The performance improvement was accompanied by an increase in step length (p < 0.001, large ηp2 = 0.717) throughout the time trial test and an increase of flight time in the split 1 and 2 (p < 0.05, moderate d = 0.793, 0.686, respectively) and vertical oscillation in the split 2 and 3 (p < 0.05, moderate d = 0.727, 0.652). However, the heart rate remained unchanged between conditions. The increase of LBS in footwear can improve 3,000 m performance without causing changes in the pacing strategy. Small modifications in running kinematics accompanied the improvements in running performance but without changes in heart rate. Moreover, LBS-increased did not affect all runners equally highlighting the need for further understanding of individual responses.

This study investigated how walking in occupational footwear (OF) affects slip outcome and slip recovery strategies in response to an unexpected slip. Participants walked along a walkway while either barefoot (BF; n = 13) or in OF (n = 12). The first five walking trials consisted of the no-slip condition, where a high friction sheet was placed halfway down the walkway to ensure a low probability of a slip. Prior to the sixth walking trial and without the participant’s knowledge, the sheet was replaced with a low friction surface to induce an unexpected slip. Results obtained during the no-slip trials indicated that compared to the BF group, the OF group walked with a 15% smaller required coefficient of friction (p = 0.04), a 12° greater dorsiflexion at heel strike (p = 0.007) and a 7° more extended knee position at 100 ms following heel strike (p = 0.008). The OF group also demonstrated greater electromyographic (EMG) activity in the hamstrings of the stance limb and the gastrocnemius of the contralateral limb prior to and after heel strike. When the low friction surface was unexpectedly encountered, a slip was induced in both groups. But compared to the BF group, the OF group experienced a less severe slip, with the slip being 42% shorter (p = 0.004) and 75% slower (p < 0.001), and exhibited a 19–71% lesser EMG activation when responding to the slip. Although these results provide initial evidence for the benefits of wearing OF to minimise the consequence of a slip in the workplace, further research is needed to determine whether the altered walking patterns associated with wearing OF (e.g., greater dorsiflexion, reduced knee range of motion, etc.) may have contributed to the decrease in slip severity.