What Does It Take to Complete the Cape Epic? Reinpõld, Karmen; Bossi, Arthur H; Hopker, James G
Journal of strength and conditioning research,
2022-Dec-01, Letnik:
36, Številka:
12
Journal Article
Recenzirano
Odprti dostop
Reinpõld, K, Bossi, AH, and Hopker, JG. What does it take to complete the cape epic? J Strength Cond Res 36(12): 3513-3520, 2022-This study aimed to describe the racing and training demands of the ...Cape Epic. Six male mountain bike riders (age: 39 ± 7 years, height: 181 ± 3 cm, and body mass: 78.7 ± 8.1 kg) trained for 4.5 months and took part in the Cape Epic. Training and racing data (prologue, stage 1, and 2) were analyzed, and riders were tested in the laboratory on 3 distinct occasions for maximal oxygen uptake (V̇O 2 max), maximal work rate (Ẇmax), and power output associated with the respiratory compensation point (RCP PO ). Statistical significance was set at p ≤ 0.05. With race durations of 1.5 ± 0.2, 6.5 ± 1.2, and 6.4 ± 1.4 hours for, respectively, prologue, stage 1, and 2, normalized power was higher in prologue (3.73 ± 0.72 W·kg -1 ) compared with stages 1 (3.06 ± 0.59 W·kg -1 , p < 0.001) and 2 (2.94 ± 0.69 W·kg -1 , p < 0.001). Riders spent more time in power zones 1 and 2 (as %RCP PO ) and less time in zones 4 and 5, during stage 2 compared with prologue (all zones p ≤ 0.028). Despite no changes in V̇O 2 max or Ẇmax, RCP PO increased from midtraining (3.89 ± 0.61 W·kg -1 ) to prerace testing (4.08 ± 0.64 W·kg -1 , p = 0.048). No differences were found between base and build training phases for time in power zones. In conclusion, the Cape Epic requires an ability to sustain high submaximal power outputs for several hours as well as an ability to repeat high-intensity efforts throughout the race. A well-balanced program, incorporating a pyramidal intensity distribution, may be used as a starting point for the design of optimal training approaches.
Contact-angle measurements were used to determine the surface energies of graphite/epoxy composites before and after grit-blasting with 80- and 220-grit garnet particles. Two different composite ...systems cured at 350°F were considered but they behaved similarly. Contact angles made by a series of liquids, including water, ethylene glycol, glycerol, formamide, and methylene iodide on as-tooled and grit-blasted composite panels were measured using a contact-angle goniometer. The contact angles were used to determine the dispersive and polar components of the surface energy
. However, instead of using the contact angles made by two liquids to determine the two components of the surface energy, we used the contact angles made by several liquids and a graphical technique to determine
and to improve the accuracy of the measurements. It was found that the surface energies of as-tooled composites were approximately 35 mJ/m
2
and were mostly dispersive; the polar components were small. After grit-blasting with 80- or 220-grit garnet, the dispersive component of the surface energy decreased somewhat whereas the polar component increased significantly; the total surface energy after grit-blasting with 80- or 220-grit garnet was approximately 50 mJ/m
2
. Etching composites in oxygen plasmas had a similar effect on the dispersive and polar components of the surface energy and on the total surface energy. Grit-blasting with 220-grit alumina resulted in higher dispersive components of surface energy and lower polar components than grit-blasting with 220-grit garnet even though the total surface energy was similar after grit-blasting with 220-grit garnet and alumina. Correcting the measured surface energies for the effects of roughness resulted in small decreases in the total surface energy of the grit-blasted composites. However, even after correcting for roughness, the surface energies of the grit-blasted composites were still significantly greater than those of the as-tooled composites, indicating that grit-blasting resulted in changes in surface chemistry as well as changes in surface morphology of the composites. These changes in surface chemistry certainly included the removal of mold release agents from the as-tooled composites but probably also involved the creation of free radicals and their reaction with atmospheric oxygen to introduce oxygen-containing functional groups on the surfaces of the composites.
To describe pacing strategy in a 24-h running race and its interaction with sex, age group, athletes' performance group, and race edition.
Data from 398 male and 103 female participants of 5 editions ...were obtained based on a minimum 19.2-h effective-running cutoff. Mean running speed from each hour was normalized to the 24-h mean speed for analyses.
Mean overall performance was 135.6 ± 33.0 km with a mean effective-running time of 22.4 ± 1.3 h. Overall data showed a reverse J-shaped pacing strategy, with a significant reduction in speed from the second-to-last to the last hour. Two-way mixed ANOVAs showed significant interactions between racing time and both athlete performance group (F = 7.01, P < .001, η
= .04) and race edition (F = 3.01, P < .001, η
= .02) but not between racing time and either sex (F = 1.57, P = .058, ηp 2 < .01) or age group (F = 1.25, P = .053, η
= .01). Pearson product-moment correlations showed an inverse moderate association between performance and normalized mean running speed in the first 2 h (r = -.58, P < .001) but not in the last 2 h (r = .03, P = .480).
While the general behavior represents a rough reverse J-shaped pattern, the fastest runners start at lower relative intensities and display a more even pacing strategy than slower runners. The "herd behavior" seems to interfere with pacing strategy across editions, but not sex or age group of runners.
Eddy-current testing (ECT) is widely used in inspection of multilayer aircraft skin structures for the detection of cracks under fasteners (CUF). Detection of deep hidden CUF poses a major challenge ...in traditional ECT techniques largely because the weak eddy-current signal due to a subsurface crack is dominated by the strong signal from the aluminum or steel fastener. Giant magnetoresistive (GMR) sensors are finding increasing applications in directly measuring weak magnetic fields associated with induced eddy currents. The measured flux image at a fastener site is in general symmetric and an asymmetry is introduced by the presence of a subsurface crack, which is used for defect detection. This paper presents novel methods that employ the resident phase information, for improving detection probability of GMR signal analysis. Using computational model, the effectiveness of the proposed methods for enhancing detection of CUF is investigated. Results demonstrating the potential of these techniques for detection of second layer CUF are presented.
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