Barefoot running improves economy at high intensities and peak treadmill velocity

Aim: Barefoot running can improve running economy (RE) compared to shod running at low exercise intensities, but data is lacking for the higher intensities typical during many distance running competitions. The influence of barefoot running on the velocity at maximal oxygen uptake (vVO2max) and peak incremental treadmill test velocity (vmax) is unknown. The present study tested the hypotheses that barefoot running would improve RE, vVO2max and vmax relative to shod running. Methods: Using a balanced within-subject repeated measures design, eight male runners (aged 23.1±4.5 years, height 1.80±0.06 m, mass 73.8±11.5 kg, VO2max 4.08±0.39 L·min-1) completed a familiarization followed by one barefoot and one shod treadmill running trial, 2-14 days apart. Trial sessions consisted of a 5 minute warm-up, 5 minute rest, followed by 4×4 minute stages, at speeds corresponding to ~67, 75, 84 and 91% shod VO2max respectively, separated by a 1 minute rest. After the 4th stage treadmill speed was incremented by 0.1 km·h-1 every 15 s until participants reached volitional exhaustion. Results: RE was improved by 4.4±7.0% across intensities in the barefoot condition (P=0.040). The improvement in RE was related to removed shoe mass (r2=0.80, P=0.003) with an intercept at 0% improvement for RE at 0.520 kg total shoe mass. Both vVO2max (by 4.5±5.0%, P=0.048) and vmax (by 3.9±4.0%, P=0.030) also improved but VO2max was unchanged (p=0.747). Conclusion: Barefoot running improves RE at high exercise intensities and increases vVO2max and vmax, but further research is required to clarify the influence of very light shoe weights on RE

A new view of responses to first-time barefoot running.

We examined acute alterations in gait and oxygen cost from shod-to-barefoot running in habitually-shod well-trained runners with no prior experience of running barefoot. Thirteen runners completed six-minute treadmill runs shod and barefoot on separate days at a mean speed of 12.5 km·h-1. Steady-state oxygen cost in the final minute was recorded. Kinematic data were captured from 30-consecutive strides. Mean differences between conditions were estimated with 90% confidence intervals. When barefoot, stride length and ground-contact time decreased while stride rate increased. Leg-and vertical stiffness and ankle-mid-stance dorsi-flexion angle increased when barefoot while horizontal distance between point of contact and the hip decreased. Mean oxygen cost decreased in barefoot compared to shod running (90% CI -11% to -3%) and was related to change in ankle angle and point-of-contact distance, though individual variability was high (-19% to +8%). The results suggest that removal of shoes produces an alteration in running gait and a potentially-practically-beneficial reduction in mean oxygen cost of running in trained-habitually-shod runners new to running barefoot. However, high variability suggests an element of skill in adapting to the novel task and that caution be exercised in assuming the mean response applies to all runners

Running Economy while Running in Extreme Cushioning and Normal Cushioning Running Shoes

The purpose of the study was to determine if running economy was influenced by wearing maximal cushioning shoes vs. control (neutral cushioning) shoes. (Please see Abstract in text

The effect of minimalist, maximalist and energy return footwear of equal mass on running economy and substrate utilization

The aim of the current study was to explore the effects of minimalist, maximalist and energy return footwear of equal mass on economy and substrate utilisation during steady state running. Ten male runners completed 6 min steady state runs in minimalist, maximalist and energy return footwear. The mass of the footwear was controlled by adding lead tape to the lighter shoes. Running economy, shoe comfort, rating of perceived exertion and % contribution of carbohydrate to total calorie expenditure were assessed. Participants also subjectively indicated which shoe condition they preferred for running. Differences in shoe comfort and physiological parameters were examined using paired samples t-tests, whilst shoe preferences were tested using a chi-square test. The results showed firstly that running economy was significantly improved in the energy return (35.9 ml∙kg/min) compared to minimalist footwear (37.8 ml∙kg/min). In addition % carbohydrate was significantly greater in the minimalist (76.4%) in comparison to energy return footwear (72.9%). As running economy was improved and carbohydrate utilisation reduced in the energy return in comparison to minimalist footwear, the current investigation shows that these footwear are more economical when shoe mass is controlled

Hyperelastic modelling of nonlinear running surfaces

Accurate, 3-D analyses of running impact require a constitutive model of the running surface that includes the material nonlinearity shown by many modern surfaces. This paper describes a hyperelastic continuum that mimics the experimentally measured response of a particular treadmill surface. The material model sacrifices a little accuracy to admit a robust, low-order hyperelastic strain-energy functional. This helps prevent the premature termination of finite element simulations, due to numerical or material instabilities, that can occur with higher-order functionals. With only two free constants, it is also a more practical design tool. The best fit to the quasi-static response of the treadmill was achieved with an initial shear modulus =2 MPa and a power-stiffening index =25. The paper outlines the method used to derive the material constants for the treadmill, a device that is not amenable to the usual materials laboratory tests and must be reverse-engineered. Finite element analyses were then performed to ensure that the treadmill model interacts with the other components of the multibody running system in a numerically stable and physically realistic manner. The model surface was struck by a rigid heel, cushioned by a hyperfoam material that represents a shoe midsole. The results show that, while the ground reaction force is similar to that obtained with a rigid surface, the maximum principal stress in the shoe is reduced by 15%. Such a reduction, particularly when endured over many load cycles, may have a significant effect on comfort and damage to nearby tissue

The Effects of Barefoot and Shod Running on Limb and Joint Stiffness Characteristics in Recreational Runners.

The authors aimed to determine the effects of barefoot (BF) and several commercially available barefoot-inspired (BFIS) footwear models on limb and joint stiffness characteristics compared with conventional footwear (CF). Fifteen male participants ran over a force platform at 4.0 m.s-1, in BF, BFIS, and CF conditions. Measures of limb and joint stiffness were calculated for each footwear. The results indicate that limb and knee stiffness were greater in BF and minimalist BFIS than in CF. CF and more structured BFIS were associated with a greater ankle stiffness compared with BF and minimalist BFIS. These findings serve to provide further insight into the susceptibility of runners to different injury mechanisms as a function of footwear

Mechanical spring technology improves running economy in endurance runners

In recent years there has been an increase in participation in timed running events. With this increase, the motivation for individuals to run their best has motivated the running shoe industry to make design changes to traditional running foot wear in an effort to improve running economy (RE) and decrease running times. One such design change has been to incorporate mechanical springs (MS) into the midsole of the running shoe. Evaluation of this technology has yet to be performed. This study recruited 17 runners (12 male) and had them run at a submaximal steady state speed for 2 bouts of five minutes at a speed of 3.13 m·sec-1. The order of shoe condition was randomly assigned and the subjects ran one interval in their own running shoe (OS) and one interval in MS shoes. Metabolic data and heart rate data were averaged over the last three of the five minute efforts. No significant difference was found between MS and OS with regards to shoe weight. Running in MS resulted in lower, non-significant values for steady state ventilation and steady state heart rate. Oxygen consumption was significantly lower in MS compared to OS in both absolute (MS: 2.35 ± 0.47 L·min-1 vs. OS: 2.40 ± 0.473 L·min-1, P=0.022) and relative (MS: 34.67 ± 4.35 ml·kg-1·min-1 vs. OS: 35.34 ± 4.58 ml·kg-1·min-1, P=0.033) terms. Running in shoes fitted with MS technology improves running economy over OS and this technology may assist athletes achieve their best running times

Increasing the midsole bending stiffness of shoes alters gastrocnemius medialis muscle function during running

In recent years, increasing the midsole bending stifness (MBS) of running shoes by embedding carbon fbre plates in the midsole resulted in many world records set during long-distance running competitions. Although several theories were introduced to unravel the mechanisms behind these performance benefts, no defnitive explanation was provided so far. This study aimed to investigate how the function of the gastrocnemius medialis (GM) muscle and Achilles tendon is altered when running in shoes with increased MBS. Here, we provide the frst direct evidence that the amount and velocity of GM muscle fascicle shortening is reduced when running with increased MBS. Compared to control, running in the stifest condition at 90% of speed at lactate threshold resulted in less muscle fascicle shortening (p= 0.006, d= 0.87), slower average shortening velocity (p = 0.002, d= 0.93) and greater estimated Achilles tendon energy return (p≤ 0.001, d= 0.96), without a signifcant change in GM fascicle work (p = 0.335, d= 0.40) or GM energy cost (p = 0.569, d= 0.30). The fndings of this study suggest that running in stif shoes allows the ankle plantarfexor muscle–tendon unit to continue to operate on a more favourable position of the muscle’s force–length–velocity relationship by lowering muscle shortening velocity and increasing tendon energy return.articl

Tibial acceleration-based prediction of maximal vertical loading rate during overground running : a machine learning approach

Ground reaction forces are often used by sport scientists and clinicians to analyze the mechanical risk-factors of running related injuries or athletic performance during a running analysis. An interesting ground reaction force-derived variable to track is the maximal vertical instantaneous loading rate (VILR). This impact characteristic is traditionally derived from a fixed force platform, but wearable inertial sensors nowadays might approximate its magnitude while running outside the lab. The time-discrete axial peak tibial acceleration (APTA) has been proposed as a good surrogate that can be measured using wearable accelerometers in the field. This paper explores the hypothesis that applying machine learning to time continuous data (generated from bilateral tri-axial shin mounted accelerometers) would result in a more accurate estimation of the VILR. Therefore, the purpose of this study was to evaluate the performance of accelerometer-based predictions of the VILR with various machine learning models trained on data of 93 rearfoot runners. A subject-dependent gradient boosted regression trees (XGB) model provided the most accurate estimates (mean absolute error: 5.39 +/- 2.04 BW.s(-1), mean absolute percentage error: 6.08%). A similar subject-independent model had a mean absolute error of 12.41 +/- 7.90 BW.s(-1) (mean absolute percentage error: 11.09%). All of our models had a stronger correlation with the VILR than the APTA (p < 0.01), indicating that multiple 3D acceleration features in a learning setting showed the highest accuracy in predicting the lab-based impact loading compared to APTA