A breakpoint in a portable near-infrared spectroscopy (NIRS) derived deoxygenated haemoglobin (deoxy[Hb]) signal during an incremental VO2max running test has been associated with the second ventilatory threshold (VT2) in healthy participants. Thus, the aim was to examine the association between this breakpoint (NIRS) and VT2 in well-trained runners. Gas exchange and NIRS data were collected during an incremental VO2max running test for 10 well-trained runners. The breakpoint calculated in oxygen saturation (StO2) and the VT2 were determined and compared in terms relative to %VO2max, absolute speed, VO2, and maximum heart rate (HRmax). There were no significant differences (p>0.05) between the breakpoint in StO2 and VT2 relative to %VO2max (87.00±6.14 and 88.28 ± 3.98 %), absolute speed (15.70±1.42 and 16.10±1.66 km·h−1), VO2 (53.71±15.17 and 54.66±15.57 ml·kg−1·min−1), and%HRmax (90.90±4.17 and 91.84±3.70%). There were large and significant correlations between instruments relative to%VO2max (r=0.68, p<0.05), absolute speed (r=0.86, p<0.001), VO2 (r=0.86, p<0.001), and %HRmax (r=0.69; p<0.05). A Bland and Altman analysis of agreement between instruments resulted in a mean difference of − 1.27±4.49%, −0.40±0.84 km·h−1,−0.90±3.07 ml·kg−1·min−1, and − 0.94±3.14 for %VO2max, absolute speed, VO2, and %HRmax, respectively. We conclude that a portable NIRS determination of the StO2 breakpoint is comparable with VT2 using gas exchange and therefore appropriate for use in determining exercise training above VT2 intensity. This is the first study to analyze the validity with the running mode using a NIRS portable device.

This study aimed to address the effects of increased longitudinal bending stiffness (LBS) on running economy (RE) and running biomechanics. A systematic search on four electronic databases (Pubmed, WOS, Medline and Scopus) was conducted on 26 May 2021. Twelve studies met the inclusion criteria and were included. Standardised mean difference with 95% confidence intervals (CI) between footwear with increased LBS vs. non-increased LBS conditions and effect sizes were calculated. To assess the potential effects of moderator variables (type and length plate, increased LBS, shoe mass and running speed) on the main outcome variable (i.e. RE), subgroup analyses were performed. Increased LBS improved RE (SMD = −0.43 [95% CI −0.58, −0.28], Z = 5.60, p < 0.001) compared to non-increased LBS. Significant increases of stride length (SMD = 0.29 [95% CI 0.10, 0.49], Z = 2.93, p = 0.003) and contact time (SMD = 0.17 [95% CI 0.03, 0.31], Z = 2.32, p = 0.02) were found when LBS was increased. RE improved to a greater degree at higher running speeds with footwear with increased LBS. RE improved 3.45% with curve plate compared to no-plate condition without improvements with flat plate shoes. When shoe mass was matched between footwear with increased LBS vs. non-increased LBS conditions, RE improved (3.15%). However, when shoe mass was not controlled (experimental condition with ∼35 grams extra), a significant small improvement was found. These RE improvements appear along with an increase of stride length and contact time. Shoe mass, type of plate (flat or curve) and running speed should be taken into consideration when designing a shoe aimed at improving long-distance running performance. KEYWORDSCarbon-fibre plate; vaporfly; energy cost of running; performance Highlights. Shoes with relatively high longitudinal bending stiffness (but not very stiff) improve running economy compared to conventional shoes. . The oxygen cost reduction was influenced by the mass of the shoe, the type of plate and the running speed. . The running economy improvements appear along with an increase of stride length and contact time.

The aim of this study was to assess the effects of adding shoe mass on running economy (RE), gait characteristics, neuromuscular variables and performance in a group of trained runners. Methods: Eleven trained runners (6 men and 5 women) completed four evaluation sessions separated by at least 7 days. The first session consisted of a maximal incremental test where the second ventilatory threshold (VT 2) and the speed associated to the VO 2max (vVO 2max) were calculated. In the next sessions, RE at 75, 85, and 95% of the VT 2 and the time to exhaustion (TTE) at vVO 2max were assessed in three different shoe mass conditions (control, +50 g and +100 g) in a randomized, counterbalanced crossover design. Biomechanical and neuromuscular variables, blood lactate and energy expenditure were measured during the TTE test. Results: RE worsened with the increment of shoe mass (Control vs. 100 g) at 85% (7.40%, 4.409 ± 0.29 and 4.735 ± 0.27 kJ•kg −1 •km −1 , p = 0.021) and 95% (10.21%, 4.298 ± 0.24 and 4.737 ± 0.45 kJ•kg −1 •km −1 , p = 0.005) of VT 2. HR significantly increased with the addition of mass (50 g) at 75% of VT 2 (p = 0.01) and at 75, 85, and 95% of VT 2 (p = 0.035, 0.03, and 0.03, respectively) with the addition of 100 g. TTE was significantly longer (∼22%, ∼42 s, p = 0.002, ES = 0.149) in the Control condition vs. 100 g condition, but not between Control vs. 50 g (∼24 s, p = 0.094, ES = 0.068). Conclusion: Overall, our findings suggest that adding 100 g per shoe impairs running economy and performance in trained runners without changes in gait characteristics or neuromuscular variables. These findings further support the use of light footwear to optimize running performance.

The NIKE Vaporfly shoe was introduced in May 2017 as part of the original #Breaking2 Project (an event aimed to run the first marathon under 2 h). This new advanced shoe technology (NAST) changed the footwear design conception. The aim of this study was (i) to analyse the effect of NAST in men’s marathon performance, (ii) to analyse whether the changes in the environmental constraints (temperature and wind) and orography of the marathons, age and birthplace of the runners has changed from 2015 to 2019 and (iii) to analyse the impact of NAST on the historical 50 best performances. Data from top-100 men's marathon performances were collected in that timeframe. The shoes used by the athletes were identified (in 91.8% of the cases) by publicly available photographs. External and environmental conditions of each marathon and age and birthplace of the runners were also analysed. Marathon performances improved from 2017 onwards between 0.75 and 1.50% compared to 2015 and 2016 (p < 0.05). In addition, the improvement was greater in the upper deciles than in the lower ones (p < 0.001). Runners wearing NAST ran ~ 1% faster in marathon compared to runners that did not use it (p < 0.001). When conducting an individual analysis of athletes who ran with and without NAST, 72.5% of the athletes who completed a marathon wearing NAST improved their performance by 0.68% (p < 0.01). External and environmental conditions, age or birthplace of runners seems not to have influenced this performance improvement. NAST has had a clear impact on marathon performance unchanged in the environmental constraints (temperature and wind), orography, age, and birthplace of the runners but with differences between venues.

Introduction/purpose Previous results about longitudinal bending stiffness (LBS) and running economy (RE) show high variability. This study aimed to assess the effects of shoes with increased LBS on RE and performance in trained and national runners. Methods Twenty-eight male runners were divided into two groups according to their 10-km performance times (trained: 38–45 min and national runners: <34 min). Subjects ran 2 x 3 min (at 9 and 13 km‧hr-1 for trained, and 13 and 17 km‧hr-1 for national runners) with an experimental shoe with carbon fiber plate to increase the LBS (Increased LBS) and a control shoe (without carbon fiber plate). We measured energy cost of running (W/kg) and spatiotemporal parameters in visit one and participants performed a 3,000 m time trial (TT) in two successive visits. Results Increased LBS improved RE in the trained group at slow (11.41 ± 0.93 vs 11.86 ± 0.93 W·kg-1) and fast velocity (15.89 ± 1.24 vs 16.39 ± 1.24 W·kg-1) and only at the fast velocity in the national group (20.35 ± 1.45 vs 20.78 ± 1.18 W·kg-1). The improvements in RE were accompanied by different changes in biomechanical variables between groups. There was a similar improvement in the 3,000 m TT test in Increased LBS for trained (639 ± 59 vs 644 ± 61 s in control shoes) and national runners (569 ± 21 vs 574 ± 21 s in control shoes) with more constant pace in increased LBS compared to control shoes in both groups. Conclusions Increasing shoe LBS improved RE at slow and fast velocities in trained and only at fast velocity in national runners. However, the 3,000 m TT test improved similarly in both levels of runners with increased LBS. The improvements in RE are accompanied by small modifications in running kinematics that could explain the difference between the different levels of runners.