A static method for obtaining a calibration factor for SRM bicycle power cranks   总被引：1，自引：0，他引：1  

Andrea L. Wooles  Anthony J. Robinson  Peter S. Keen 《Sports Engineering》2005,8(3):137-144

Many scientists and coaches are interested in mechanical power produced during cycling, and use Schoberer Rad Me\technik (SRM) bicycle power cranks to obtain this data. However, it has been expensive and difficult to calibrate SRM cranks, causing much of the collected data to be unreliable. We present a static method, derived from first principles, for obtaining a calibration factor for SRM cranks. A known mass and lever arm (chainring of a known diameter) are used to apply a known torque load to the instrument in four positions, and the output frequencies are used to calculate the calibration factor in Hz/Nm. The reproducibility of this method is ±0.01 Hz/Nm, which is acceptable for the application of the instrument, which is measurement of mechanical power application by cyclists at the crank. The method is reliable, inexpensive, and easy to set up, and will allow higher confidence in data collected using SRM power cranks. We recommend calibration of the power meter once every six months because of the measured drift of the calibration factor over time.  相似文献   

Effects of dynamic upper-body exercise on lower-limb isometric endurance     

Easton C  Finlay C  Findlay C  Morrison G  Spurway NC 《Journal of sports sciences》2007,25(10):1101-1107

Following preliminary indications that in some individuals arm exercise enhanced rather than reduced simultaneous leg endurance, ten young men and women performed three forms of intermittent work to volitional exhaustion, under duty cycles of 45 s work, 15 s rest. The protocols were as follows: (A) knee extensions at 30% maximum voluntary contraction (MVC); (B) 30% MVC knee extensions combined with arm cranking at 130% of their own lactate threshold; (C) combined 30% MVC knee extensions and arm cranking at 20% of their own lactate threshold. Heart rate, oxygen uptake (VO(2)), and blood lactate concentration were among the variables recorded throughout. All physiological indicators of demand were substantially higher in protocol B than in protocols A or C [heart rate: (A) 154 beats . min(-1), (B) 171 beats . min(-1), (C) 150 beats . min(-1); VO(2): (A) 11.9 ml . kg(-1) . min(-1), (B) 21.7 ml . kg(-1) . min(-1), (C) 14.2 ml . kg(-1) . min(-1); blood lactate concentration: (A) 3.3 mmol . l(-1), (B) 5.1 mmol . l(-1), (C) 2.8 mmol . l(-1)], yet there were no significant differences (P > 0.05) in the endurance times between the three conditions [(A) 11.43 min, (B) 11.1 min, (C) 10.57 min] and seven participants endured longest in protocol B. Results from protocol (C) cast doubt on explanations in terms of psychological distraction. We suggest that lactic acid produced by the arms is shuttled to the legs and acts there either as a supplementary fuel source or as an antagonist to the depressing effects of increased potassium concentration.  相似文献   

Validation of a laboratory and hospital information system in a medical laboratory accredited according to ISO 15189     

Biljak VR  Ozvald I  Radeljak A  Majdenic K  Lasic B  Siftar Z  Lovrencic MV  Flegar-Mestric Z 《Biochemia medica : ?asopis Hrvatskoga dru?tva medicinskih biokemi?ara / HDMB》2012,22(1):86-91

Introduction

The aim of the study was to present a protocol for laboratory information system (LIS) and hospital information system (HIS) validation at the Institute of Clinical Chemistry and Laboratory Medicine of the Merkur University Hospital, Zagreb, Croatia.

Materials and methods:

Validity of data traceability was checked by entering all test requests for virtual patient into HIS/LIS and printing corresponding barcoded labels that provided laboratory analyzers with the information on requested tests. The original printouts of the test results from laboratory analyzer(s) were compared with the data obtained from LIS and entered into the provided template. Transfer of data from LIS to HIS was examined by requesting all tests in HIS and creating real data in a finding generated in LIS. Data obtained from LIS and HIS were entered into a corresponding template. The main outcome measure was the accuracy of transfer obtained from laboratory analyzers and results transferred from LIS and HIS expressed as percentage (%).

Results:

The accuracy of data transfer from laboratory analyzers to LIS was 99.5% and of that from LIS to HIS 100%.

Conclusion:

We presented our established validation protocol for laboratory information system and demonstrated that a system meets its intended purpose.  相似文献   

Repeated exercise stress impairs volitional but not magnetically evoked electromechanical delay of the knee flexors     

Minshull C  Eston R  Bailey A  Rees D  Gleeson N 《Journal of sports sciences》2012,30(2):217-225

The effects of serial episodes of fatigue and recovery on volitional and magnetically evoked neuromuscular performance of the knee flexors were assessed in 20 female soccer players during: (i) an intervention comprising 4 × 35 s maximal static exercise, and (ii) a control condition. Volitional peak force was impaired progressively (-16% vs. baseline: 235.3 ± 54.7 to 198.1 ± 38.5 N) by the fatiguing exercise and recovered to within -97% of baseline values following 6 min of rest. Evoked peak twitch force was diminished subsequent to the fourth episode of exercise (23.3%: 21.4 ± 13.8 vs. 16.4 ± 14.6 N) and remained impaired at this level throughout the recovery. Impairment of volitional electromechanical delay performance following the first episode of exercise (25.5%: 55.3 ± 11.9 vs. 69.5 ± 24.5 ms) contrasted with concurrent improvement (10.0%: 24.5 ± 4.7 vs. 22.1 ± 5.0 ms) in evoked electromechanical delay (P < 0.05), and this increased disparity between evoked and volitional electromechanical delay remained during subsequent periods of intervention and recovery. The fatiguing exercise provoked substantial impairments to volitional strength and volitional electromechanical delay that showed differential patterns of recovery. However, improved evoked electromechanical delay performance might identify a dormant capability for optimal muscle responses during acute stressful exercise and an improved capacity to maintain dynamic joint stability during critical episodes of loading.  相似文献   

Comparison of power and EMG during 6-s all-out cycling between young and older women     

CR Duffy  D Stewart  F Pecoraro  PE Riches  D Farina  A Macaluso 《Journal of sports sciences》2012,30(12):1311-1321

Abstract To investigate the effects of ageing on the neural control strategies governing sprint cycling on a friction-loaded cycle-ergometer, 10 older (aged 70-83yr) and 8 young (aged 19-35yr) healthy women completed seven 6-s all-out cycling trials against varying loads. Root mean square (RMS), median frequency and muscle fibre conduction velocity were determined from the vastus lateralis of the dominant limb during each pedal stroke. Peak power was 43% lower in the older group compared to the younger (p??0.05). ΔRMS from the first to the sixth second during each trial was found to increase significantly with the development of power output in both groups (p?相似文献   

A faster running speed is associated with a greater body weight loss in 100-km ultra-marathoners     

Knechtle B  Knechtle P  Wirth A  Alexander Rüst C  Rosemann T 《Journal of sports sciences》2012,30(11):1131-1140

In 219 recreational male runners, we investigated changes in body mass, total body water, haematocrit, plasma sodium concentration ([Na(+)]), and urine specific gravity as well as fluid intake during a 100-km ultra-marathon. The athletes lost 1.9 kg (s = 1.4) of body mass, equal to 2.5% (s = 1.8) of body mass (P < 0.001), 0.7 kg (s = 1.0) of predicted skeletal muscle mass (P < 0.001), 0.2 kg (s = 1.3) of predicted fat mass (P < 0.05), and 0.9 L (s = 1.6) of predicted total body water (P < 0.001). Haematocrit decreased (P < 0.001), urine specific gravity (P < 0.001), plasma volume (P < 0.05), and plasma [Na(+)] (P < 0.05) all increased. Change in body mass was related to running speed (r = -0.16, P < 0.05), change in plasma volume was associated with change in plasma [Na(+)] (r = -0.28, P < 0.0001), and change in body mass was related to both change in plasma [Na(+)] (r = -0.36) and change in plasma volume (r = 0.31) (P < 0.0001). The athletes consumed 0.65 L (s = 0.27) fluid per hour. Fluid intake was related to both running speed (r = 0.42, P < 0.0001) and change in body mass (r = 0.23, P = 0.0006), but not post-race plasma [Na(+)] or change in plasma [Na(+)] (P > 0.05). In conclusion, faster runners lost more body mass, runners lost more body mass when they drank less fluid, and faster runners drank more fluid than slower runners.  相似文献   

Does sensorimotor training improve the static balance of young volleyball players?     

Pau M  Loi A  Pezzotta MC 《Sports biomechanics / International Society of Biomechanics in Sports》2012,11(1):97-107

The aim of this investigation is to assess the effectiveness of a 6-week balance training (BT) protocol, integrated in regular training sessions, on postural sway of young female volleyball players (n = 26, age 13.0 +/- 0.2 years) divided into two groups (intervention and control; 13 per group). Trials were performed for bipedal and unipedal stance conditions before and after the BT protocol, using a pressure platform to collect center-of-pressure (COP) time series that were processed to calculate sway area, COP path length, and maximum displacement range in anteroposterior and mediolateral directions. The intervention group exhibited smaller sway areas in eyes closed conditions (intervention = 42.76 mm2, control = 67.60 mm2; p < 0.05) and Romberg quotients (intervention = 1.11 mm, control = 1.82 mm) in bipedal stance, while all the other parameters were unaffected. BT also reduced sway area (intervention = 122.70 mm2, control = 187.18 mm2) and anteroposterior COP displacements (intervention = 20.18 mm, control = 22.38 mm) of the non-dominant limb for single-leg stance. No significant change was found for the dominant limb. Although it is possible to hypothesize a beneficial effect of BT on young athletes, further investigations are required to clarify its actual effect on balance performance with respect to normal volleyball training.  相似文献   

Comparison of heart rate monitoring with indirect calorimetry for energy expenditure evaluation     

Zhusheng Yu  Eszter Völgyi  Ru Wang  Andrea Ember  Petri Wiklund  Markku Alén  Frances A. Tylavsky  Sulin Cheng 《运动与健康科学(英文)》2012,1(3):178-183

PurposeThe purpose of this study was to compare established methods with newly-developed methods for estimating the total energy expenditure (TEE).MethodsThe study subjects comprised 46 individuals, including 16 middle-aged men (mean age 51.4 years), 14 middle-aged women (mean age 49.9 years) and 16 young women (mean age 19.1 years). The TEE was estimated from 24-h heart rate (HR) data using newly-developed software (MoveSense HRAnalyzer 2011a, RC1, Suunto Oy, Vantaa, Finland), and was compared against the TEE determined using doubly labeled water (DLW). Agreement between the two methods was analyzed using Bland and Altman plots.ResultsThe HR method yielded similar TEE values as the DLW method at the group level, with an average of 8.6 kcal/day in the difference in the mean, but with large individual variations. Forty-four (96%) out of 46 subjects fell within ±2SD of the mean difference in TEE comparisons, and there was no tendency towards under- or over-estimation.ConclusionOur results indicate that the current software using HR analysis for the estimation of daily TEE needs further development for use with free-living individuals.  相似文献   

Child protection and justice systems processing of serious child abuse and neglect cases     

Sedlak AJ  Schultz D  Wells SJ  Lyons P  Doueck HJ  Gragg F 《Child abuse & neglect》2006,30(6):657-677

OBJECTIVE: The aim of this study was to examine the trajectory of cases through four systems: child protection, law enforcement, the dependency courts, and the criminal courts. METHOD: This study focused on a county selected from a 41-county telephone survey conducted for the National Incidence Study of Child Abuse and Neglect (NIS-3). For this analysis prospective samples were drawn from law enforcement (n=225) and the county child protection (CPS) agency (n=225) and followed through in-depth case tracking across all agencies and through both the dependency and criminal court systems. RESULTS: The percentage of CPS cases opened in dependency court was similar to prior studies (29%), but the acceptance and prosecution rates were much higher--92% of the cases referred from CPS, including many cases of physical abuse. Compared to referrals from CPS to law enforcement (93%), few cases were referred from law enforcement to CPS (17%). Anecdotally, case referral patterns appeared to be influenced by communication patterns and mutual positive regard, regardless of the collaborative protocols in place. One of the most instructive findings was the degree of difficulty in tracking cases across organizations and the types of obstacles that impeded success. Disorganization was not an issue, rather internal structures set up to facilitate intra-organizational processing were the same structures that actually impeded cross-organizational case finding. CONCLUSIONS: It is not sufficient to rely on the existence of multi-disciplinary teams or Child Advocacy Centers to ensure collaboration. More attention to daily tasks and activities as well as the nature and quality of communication is warranted. On the technical side, use of common case identifiers on cases that are cross-referred is strongly recommended. Future studies should broaden the scope of inquiry to include the consequences of all case trajectories, rather than solely focusing on the justice system.  相似文献   

Semi‐automating the manual literature search for systematic reviews increases efficiency     

Andrea L. Chapman  Laura C. Morgan  Gerald Gartlehner 《Health information and libraries journal》2010,27(1):22-27

Background: To minimise retrieval bias, manual literature searches are a key part of the search process of any systematic review. Considering the need to have accurate information, valid results of the manual literature search are essential to ensure scientific standards; likewise efficient approaches that minimise the amount of personnel time required to conduct a manual literature search are of great interest. Objective: The objective of this project was to determine the validity and efficiency of a new manual search method that utilises the scopus ? database. Methods: We used the traditional manual search approach as the gold standard to determine the validity and efficiency of the proposed scopus method. Outcome measures included completeness of article detection and personnel time involved. Using both methods independently, we compared the results based on accuracy of the results, validity and time spent conducting the search, efficiency. Results: Regarding accuracy, the scopus method identified the same studies as the traditional approach indicating its validity. In terms of efficiency, using scopus led to a time saving of 62.5% compared with the traditional approach (3 h versus 8 h). Conclusions: The scopus method can significantly improve the efficiency of manual searches and thus of systematic reviews.  相似文献