To estimate how much of an improvement in distance running performance would be

To estimate how much of an improvement in distance

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To estimate how much of an improvement in distance- running performance would be predicted from a reduction in the energetic cost of running in NVF compared with NZM shoes, we used the curvilinear relationship between running velocity and aerobic energy expenditure recently described by Hoogkamer et al. [ 10 ] and based on data from Tam et al. [ 15 ], with velocity ( V ) in m·s −1 : To analyze the effects of actual improvement in racing performance in the NVF shoes (in terms of running velocity) compared with baseline performance in the subject’s own racing spikes, a spreadsheet for post-only crossovers [ 24 ] was used for analysis. Effects were estimated in percent units via log transformation, and uncertainty in the estimate was expressed as 90% CLs. 3 Results The running economy, O 2 COT, and energetic cost data for each of the four shoe models at all four running velocities are presented in Table  2 . The NVF shoe improved run- ning economy by 4.2 ± 1.2%, on average, across all run- ning speeds compared with ADI, and 2.6 ± 1.3% compared with NZM. When weighted to match the mass of ADI, the NVF + was still, on average, 2.9 ± 1.3% more effficient than ADI across all running speeds. Notably, all subjects were more effficient in NVF than ADI, and only two subjects were more effficient in NZM than NVF (only at the fastest running velocities) (Fig.  2 ). Among the 24 subjects, the difference in running economy over the four velocities between the NVF and ADI shoes ranged from − 1.72 to − 7.15% and from + 0.50 to − 5.34% for NVF versus NZM, indicating consid- erable interindividual variation in the amount of energetic saving the NVF shoes provided. Percent change scores and effects for differences between shoe models at each of the four running velocities is presented in Table  3 . There were small to moderate differences between all shoe types at 14 and 16 km·h −1 , trivial to small differences at 15 km·h −1 , and VO 2 ( ml kg - 1 min - 1 ) = 5.7 + 9.8158 × V + 0.0537 × V 3 . moderate to large differences at 18 km·h −1 (all p ≤ 0.008). Differences in heart rate between shoe conditions were triv- ial (ES < 0.13, p > 0.31). Differences in running economy between men and women are presented in Table  4 . There were trivial to small differences between men and women at 14 km·h −1 (ES = 0.11–0.38) and 16 km·h −1 (ES = 0.17–0.50). All RER values remained below 0.9 for all trials, and [La] values while running 18 km·h −1 for men ([La] = 2.6 ± 0.7 mmol·L −1 ) and 16 km·h −1 for women ([La] = 3.3 ± 0.5 mmol·L −1 ) remained at an intensity below the onset of blood lactate accumulation (OBLA), which speciff es an [La] of 4 mmol·L −1 [ 16 ]. While running in the NVF shoes, subjects generally ran with longer contact time and ffight times, slower stride rate, and a longer stride length than the NZM (Table  5 ).
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  • Fall '16
  • KaraCross

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