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71.
Colin M. Robertson Samuel A. Pullinger William R. Robinson Mathew E. Smith Jatin G. Burniston James M. Waterhouse 《Chronobiology international》2013,30(10):1391-1401
ABSTRACTWe have investigated the magnitude of diurnal variation in back squat and bench press performance using the MuscleLab force velocity transducer. Thirty resistance-trained males (mean ± SD: age 21.7 ± 1.4 years; body mass 80.5 ± 4.5 kg; height 1.79 ± 0.06 m) underwent two sessions at different times of day: morning (M, 07:30 h) and evening (E, 17:30 h). Each session included a period when rectal temperature (Trec) was measured at rest, a 5-min standardized 150 W warm-up on a cycle ergometer, then defined programme of bench press (at 20, 40 and 60 kg) and back squat (at 30, 50 and 70 kg) exercises. A linear encoder was attached to an Olympic bar used for the exercises and average force (AF), peak velocity (PV) and time-to-peak velocity (tPV) were measured (MuscleLab software; MuscleLab Technology, Langesund, Norway) during the concentric phase of the movements. Values for Trec at rest were higher in the evening compared to morning values (0.48°C, P < 0.0005). Daily variations were apparent for both bench press and back squat performance for AF (1.9 and 2.5%), PV (8.3 and 12.7%) and tPV (?16.6 and ?9.8%; where a negative number indicates a decrease in the variable from morning to evening). There was a main effect for load where AF and tPV increased and PV decreased from the lightest load to the heaviest for both bench press and back squat (47.1 and 80.2%; 31.7 and 57.7%; ?42.1 and ?73.9%; P < 0.0005 where a negative number indicates a decrease in the variable with increasing load). An interaction was found only for tPV, such that the tPV occurs earlier in the evening than the morning at the highest loads (60 and 70 kg) for both bench press and back squat, respectively (mean difference of 0.32 and 0.62 s). In summary, diurnal variation in back squat and bench press was shown; and the tPV in complex multi-joint movements occurs earlier during the concentric phase of exercise when back squat or bench press is performed in the evening compared to the morning. This difference can be detected using a low cost, portable and widely available commercial instrument and enables translation of past laboratory/tightly controlled experimental research in to main-stream coaching practice. 相似文献
72.
E.R. Vazquez J.H. Pierluissi 《Computer methods in biomechanics and biomedical engineering》2014,17(2):119-127
Acoustic reflectometry is often used for estimating the cross-sectional area of a cylindrical cavity when used in combination with an acoustic pulse. The objective of this research is to sweep a spectral bandwidth from 50 Hz to 10 kHz at steps of 50 Hz, with Gaussian sinusoidal wave packets, and to apply the Ware–Aki algorithm. In practice, not only it is difficult to generate a broad spectral bandwidth, but also robust methods are required to compensate for attenuation in the propagating wave and to eliminate a DC offset component generated in its impulse response. This paper looks at using numerical techniques to compute the impulse response and estimate the cross-sectional area as a function of an increment in the frequency response. Preliminary results show that both simulated and reconstructed cross-sectional areas for an in vitro model of a human upper airway may be estimated with an appropriate resolution, suggesting that this method is suitable for such applications. 相似文献
73.
H.G. Ferrari C.A. Gobatto F.B. Manchado-Gobatto 《Biology of sport / Institute of Sport》2013,30(4):289-294
This study aimed to evaluate the leukocyte subset counts, serum immunoglobulin A, performance and upper respiratory symptoms (URS), as well as their interrelationships, of well-trained cyclists for a 29-week training season using monitored loads. The season was divided into three phases: preparatory (nine weeks), first competitive phase (nine weeks) and second competitive phase (11 weeks). The sample consisted of eight well-trained cyclists, aged 18 ± 2 years. Immunological parameters and performance were evaluated during weeks 1 (baseline), 10 (early first competitive phase), 19 (early second competitive phase) and 29 (end of the second competitive phase). The training loads (volume x rating of perceived exertion) were monitored daily while the monitoring of URS was performed every 15 days using the WURSS-44 questionnaire. The data were analyzed using a one-way ANOVA and a Pearson correlation test with the significance level set at p ≤ 0.05. No significant differences were found for training load, leukocyte subset counts or serum immunoglobulin A among the three phases. However, serum immunoglobulin A was 50.9% below the control group values. URS were significantly higher during the preparatory period, and there were significant correlations between URS and training load (strain) in the preparatory period (r = 0.72, p = 0.032) and second competitive phase (r = 0.73, p = 0.036). In conclusion, indicators of training load without a significant change throughout the season did not significantly affect immune parameters measured; however, the increase of strain can cause an increase of upper respiratory symptoms throughout the season, but without loss of performance. 相似文献
74.
75.
RON WIBEL EMANUEL J. VACCHIANO JOHN J. MACIEJEWSKI HOWARD E. BUHSE Jr. JOHN CLAMP 《The Journal of eukaryotic microbiology》1997,44(5):457-466
ABSTRACT. We examined by SEM and TEM the stalk-scopular junction, the stalk, and stalk formation in Vorticella convallaria Linnaeus, 1767. The stalk sheath is anchored to the walls of the scopular lip and to the scopular cilia by thin fibrils. Experimental extraction of these fibrils weakens this junction enough to separate the stalk from the cell body. Telotrochs escape from the stalk by means of violent contractions of the cell body, accelerated beating of the trochal band cilia, and twisting of the cell body against the stalk. The edges of the scopular lip spread over the scopular cilia after escape and, in some cases, fuse to enclose the entire, aboral scopular surface in a cupola-like structure. The sessile cells contain fewer and smaller scopular granules than telotrochs. The presence of disintegrating scopular granules in the stalk matrix of some sessile cells suggests that they contain material which is secreted over a period of time to form the stalk. Eruptive formation of the initial adhesive pad and quick elongation of the distal part of the stalk suggests a rapid exocytosis of the larger, more numerous granules of the telotroch. The stalk sheath is formed of fibrils making up complete and incomplete compartments peripherally arranged along the major stalk axis. 相似文献
76.
Orofacial and thumb-index finger ramp-and-hold isometric force dynamics in young neurotypical adults
The relation among several parameters of the ramp-and-hold isometric force contraction (peak force and dF/dtmax during the initial phase of force recruitment, and the proportion of hold-phase at target) was quantified for the right and left thumb-index finger pinch, and lower lip midline compression in 40 neurotypical right-handed young adults (20 female/20 males) using wireless force sensors and data acquisition technology developed in our laboratory. In this visuomotor control task, participants produced ramp-and-hold isometric forces as ‘rapidly and accurately’ as possible to end-point target levels at 0.25, 0.5, 1 and 2 Newtons presented to a computer monitor in a randomized block design. Significant relations were found between the parameters of the ramp-and-hold lip force task and target force level, including the peak rate of force change (dF/dtmax), peak force, and the criterion percentage of force within ±5% of target during the contraction hold phase. A significant performance advantage was found among these force variables for the thumb-index finger over the lower lip. The maximum voluntary compression force (MVCF) task revealed highly significant differences in force output between the thumb-index fingers and lower lip (∼4.47–4.70 times greater for the digits versus lower lip), a significant advantage of the right thumb-index finger over the non-dominant left thumb-index finger (12% and 25% right hand advantage for males and females, respectively), and a significant sex difference (∼1.65–1.73 times greater among males). 相似文献
77.
78.
目的:探讨兰索拉唑联合奥曲肽治疗急性非静脉曲张性上消化道出血的临床疗效以及安全性。方法:选取自2014年1月到2017年1月我院收治的急性非静脉曲张性上消化道出血患者102例,随机分为A组、B组和C组,每组各34例。A组使用兰索拉唑进行治疗,B组使用奥曲肽进行治疗,C组联合使用兰索拉唑和奥曲肽进行治疗。对比三组患者的临床疗效、止血时间、血压稳定时间、胃管引流量、胃液PH值以及不良反应的发生情况。结果:治疗后,C组的显效率为61.76%,显著高于A组和B组(均P0.05);C组的总有效率为97.06%,显著高于B组(P0.05);C组的止血时间为(15.37±4.38)h,血压稳定时间为(7.23±1.18)h,胃管引流量为(236.59±29.81)mL,均显著少于A组和B组,而胃液PH值为(5.91±0.57),显著高于A组和B组(均P0.05)。三组患者不良反应发生率的对比差异均没有统计学意义(P0.05)。结论:兰索拉唑联合奥曲肽治疗急性非静脉曲张性上消化道出血可显著提高止血效果,临床疗效明显优于单用兰索拉唑或奥曲肽治疗,且安全性相当。 相似文献
79.
Thermal resistance and upper lethal temperatures of underyearling Lake Inari Arctic charr 总被引:1,自引:0,他引:1
Underyearling Arctic charr were acclimated to six temperatures between 6 and 21·5°C and thermal tolerance and resistance were tested after an acclimation period of at least 2 weeks. Resistance times were influenced by acclimation temperature and the highest upper incipient lethal temperature was 23–24°C. An upper limit for cultivation of Lake Inari charr is suggested to be 21°C which is the intercept of the function which represents the upper limit of the thermal tolerance zone. 相似文献
80.
Trabecular architecture and joint loading of the proximal humerus in extant hominoids,Ateles, and Australopithecus africanus
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Tracy L. Kivell Rebecca Davenport Jean‐Jacques Hublin J. Francis Thackeray Matthew M. Skinner 《American journal of physical anthropology》2018,167(2):348-365