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Purpose: We compared running economy (RE) and 3-km time-trial (TT) variables of runners wearing Nike Vaporfly 4% (VP4), Saucony Endorphin lightweight racing flats (FLAT), and their habitual running (OWN) footwear., Methods: Eighteen male recreational runners (age = 33.5 ± 11.9 year (mean ± SD), peak oxygen uptake (VO 2peak ) = 55.8 ± 4.4 mL/kg·min) attended 4 sessions approximately 7 days apart. The first session consisted of a VO 2peak test to inform subsequent RE speeds set at 60%, 70%, and 80% of the speed eliciting VO 2peak . In subsequent sessions, treadmill RE and 3-km TTs were assessed in the 3 footwear conditions in a randomized, counterbalanced crossover design., Results: Oxygen consumption (mL/kg·min) was less in VP4 (from 4.3% to 4.4%, p ≤ 0.002) and FLAT (from 2.7% to 3.4%, p ≤ 0.092) vs. OWN across intensities, with a non-significant difference between VP4 and FLAT (1.0%-1.7%, p ≥ 0.292). Findings related to energy cost (W/kg) and energetics cost of transport (J/kg·m) were comparable. VP4 3-km TT performance (11:07.6 ± 0:56.6 mm:ss) was enhanced vs. OWN by 16.6 s (2.4%, p = 0.005) and vs. FLAT by 13.0 s (1.8%, p = 0.032). The 3-km times between OWN and FLAT (0.5%, p = 0.747) were similar. Most runners (n = 11, 61%) ran their fastest TT in VP4., Conclusion: Overall, VP4 improved laboratory-based RE measures in male recreational runners at relative speeds compared to OWN, but the RE improvements in VP4 were not significant vs. FLAT. More runners exhibited better treadmill TT performances in VP4 (61%) vs. FLAT (22%) and OWN (17%). The variability in RE (-10.3% to 13.3%) and TT (-4.7% to 9.3%) improvements suggests that responses to different types of shoes are individualized and warrant further investigation., (Copyright © 2020. Production and hosting by Elsevier B.V.)

We compared biomechanical and subjective data from outdoor running in: habitual (OWN), Saucony Endorphin Racer 2 minimal (FLAT) and Nike Vaporfly 4% (VP4) shoes. We also explored relationships between comfort measures and the collected data. Eighteen male recreational runners ran three 1.5-km trials outdoors, once per shoe. The first 1.1 km was run at a self-selected comfortable (slower) speed, and last 400 m at perceived 5-km race pace (faster). A GPS-enabled smartwatch, 15-m Optojump system, high-speed camera and tibial accelerometer collected biomechanical data. Subjective data on comfort, shoe properties and overall running experience were collected using visual analogue scales (VAS) and rankings. Cadence, leg stiffness and vertical stiffness were greater in FLAT than both OWN and VP4 at the slower speed (trivial to small ES). At both speeds, footstrike angles were smaller in FLAT (small to large ES), while propulsion phase was shorter in VP4 (moderate to large ES). FLAT was ranked as the least comfortable at the slower speed and most likely to cause injury, whereas OWN as the most comfortable and least likely to cause injury. Comfort was not significantly different at the faster speed between shoes. Comfort measures were more strongly correlated to subjective than biomechanical data. The two experimental shoes generally had non-significant or small effects on running biomechanics versus OWN. As VP4 are more like traditional than minimal shoes, these were perceived as more comfortable. Running speed appeared to affect subjective measures. Speed should be considered when prescribing and selecting shoes. [ABSTRACT FROM AUTHOR]

Objectives To compare hip kinematics during two functional tasks in females with and without patellofemoral pain (PFP), and to determine if hip kinematics and, symptoms and functional limitations were improved after a rehabilitation program. Design Cross sectional and longitudinal. Participants Sixteen females with and 15 without PFP. Setting Laboratory and physical therapy clinic. Main outcome measures Hip adduction (HADD) and medial rotation (HMR) peak angles, time integrals and inter-movement variability during step-down and vertical drop jump, symptoms and functional limitations evaluated using the Activities of Daily Living Scale of the Knee Outcome Survey (KOS-ADLS). Results At baseline, no significant differences were found in step-down and vertical drop jump between PFP and controls. Following rehabilitation, significant improvements were reported in KOS-ADLS (p < 0.001). There was a significant decrease in HADD and HMR variability (p < 0.05), a trend for decreased peak HMR (p = 0.06) during step-down, and a significant decrease in HADD variability (p < 0.05) during vertical drop jump. These kinematic changes did not correlate with changes in KOS-ADLS (all p > 0.05). Conclusion Females with and without PFP demonstrated no hip kinematic differences during functional tasks. A rehabilitation program improved symptoms and functional status, and modified hip kinematics in females with PFP; however these changes were not correlated. [ABSTRACT FROM AUTHOR]