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Biomedical subjects

D Bishop

Publications and source records attributed to D Bishop.

At least 19 recordsLinked to original sources
PubMed2001

The validity of a repeated sprint ability test.

Many team sports require participants to repeatedly produce maximal or near maximal sprints of short duration (1-7s) with brief recovery periods, over an extended period of time (60-90 min). Therefore, an important fitness component for these sports is what is often termed repeated sprint ability (RSA). A variety of tests have been devised to assess RSA. However, while the reliability of some of these tests has been reported, there has been no published attempt to assess the validity of RSA tests. The purpose of the present paper was to assess the validity of a popular RSA test--the 5 x 6 s cycle test. Ten moderately-trained males (Mean+/-SD age: 23.6+/-3.0 yrs, mass: 71.8+/-7.4 kg, peak VO2: 46.32+/-4.16 ml.kg(-1)min(-1)) participated in the investigation. Following familiarisation, subjects reported to the laboratory at the same time of day, on three occasions, each separated by at least 48 hours. Testing consisted of a 5 x 6 s cycle test (5 x 6 s maximal sprints every 30 s), a graded exercise test (GXT) and a simulated game (3 x 15 min periods separated by five min). The simulated game consisted of a 1-min circuit that was repeated 15 times in each period. The circuit replicated typical movement patterns observed during motion analysis of field hockey games. Each circuit commenced with a 15-m maximum sprint through timing gates. Time to run 5, 10 and 15 m was recorded. Oxygen consumption was measured during both the GXT and the simulated game with a portable gas analysis system (Cosmed K4 b2, Italy). Correlation coefficients between dependent variables were calculated using Pearson's Product Moment (r). There was a significant correlation between power decrement during the 5 x 6 s cycle test and decrement in 15-m time across the three periods (r = 0.76, P<0.05), but not decrement in 10-m time (r = 0.54) or 5-m time (r = 0.42). These results suggest that the 5 x 6 s cycle test is valid for assessing the decrement in 15-m time, but not the decrement in 5 or 10m time. Thus, one measure of RSA (sprint decrement) appears to be specific to the test protocol, rather than a general quality. The most likely explanation is that the energy requirements of the 5 x 6 s cycle test more closely match those required to repeatedly run 15 m (mean time = 2.74 s) than to repeatedly run 10 m (mean time = 1.97 s) or 5 m (mean time = 1.13 s). It is therefore suggested that, while the 5 x 6 s cycle test is often used to assess RSA ability in a wide range of sports, it may need to be modified to reflect the common sprint distances found in specific sports.

Adult↗
PubMed2001

Evaluation of the Accusport lactate analyser.

It has been suggested that lactate concentrations may provide a guide to an optimal training intensity. However, lactate concentrations established during incremental exercise in the laboratory are not always indicative of what is occurring during constant-load exercise at the same intensity. Ideally, lactate concentrations should be measured during a training session and immediately reported to the athlete to ensure that the athlete is working at the desired intensity. The purpose of this investigation was, therefore, to determine the reliability and validity of a compact, portable lactate analyser (ACCUSPORT; Boeringer Mannheim, Castle Hill, Australia). A total of 224 capillary blood samples were taken from athletes who took part in routine laboratory testing. Seventy-three of these capillary blood samples were analysed in duplicate with the Accusport for determination of intraclass, single-trial reliability. Day-to-day intraclass reliability of the Accusport was assessed by analyzing known concentrations of aqueous lactate solutions on seven consecutive days. The validity of the Accusport analyser was assessed by comparing the 224 capillary blood lactate concentrations determined on the Accusport with the lactate concentration obtained using a MICRO STAT LM3 (Analox Instruments Ltd., London, UK). In addition, lactate parameters derived from the lactate concentrations obtained with the two analysers were compared. The Accusport showed high single-trial intraclass reliability (R = 0.992; Standard Error of Measurement [SE(M)] = 0.3 mmol x l(-1); n = 73) and high day-to-day intraclass reliability (R = 0.993; SE(M) = 0.4 mmol x l(-1); n = 42). Despite a strong correlation between blood lactate concentrations obtained on the two analysers (r = 0.96; n = 224) the limits of agreement were + 1.9 to - 2.2 mmol x l(-1). Although the mean values for power output, HR and lactate concentration associated with the lactate parameters were not significantly different when determined on the Accusport or Micro Stat, some individuals did record large differences between analysis methods. In summary, the results of this investigation have shown that lactate concentrations can be reliably determined within a single trial and from day-to-day using the Accusport analyser. However, for some athletes, it is not valid to compare lactate concentrations or lactate parameters determined on the Accusport with those determined using the Micro Stat LM3 lactate analyser.

Adult↗
PubMed2001

The effect of three different warm-up intensities on kayak ergometer performance.

PURPOSE: The purpose of this study was to investigate the influence of warm-up (WU) intensity on supramaximal kayak ergometer performance. METHODS: In the initial testing session, eight institute of sport kayak squad members performed a graded exercise test for determination of VO2max and lactate (La) parameters. In a random, counterbalanced order, subjects subsequently performed WU for 15-min at either their aerobic threshold (W1), their anaerobic threshold (W3), or mid-way between their aerobic threshold and anaerobic threshold (W2). A 5-min passive rest period and then a 2-min, all-out kayak ergometer test followed the WU. RESULTS: For the three different WU conditions, no significant differences were observed for average power, peak VO2, total VO2, total VCO2, or accumulated oxygen deficit (AOD) during the 2-min test. However, when compared with W3, differences in average power approached significance after both W1 (P = 0.09) and W2 (P = 0.10). Furthermore, when compared with W3, average power during the first half of the 2-min test was significantly greater after W2 (P < 0.05) and approached significance after W1 (P = 0.06). After each WU period, there was a significant difference in blood pH (W1>W2>W3; P < 0.05) and blood [La] (W1<W2<W3; P < 0.05). Despite the significantly different metabolic acidemia after each WU condition, there were no significant differences in the VO2 responses to the 2-min test. However, the greater metabolic acidemia after W3 was associated with impaired 2-min kayak ergometer performance. CONCLUSIONS: It was concluded, that although a degree of metabolic acidemia may be necessary to speed O2 kinetics, if the WU is too intense, the associated metabolic acidemia may impair supramaximal performance by reducing the anaerobic energy contribution and/or interfering with muscle contractile processes.

Adolescent↗
PubMed2001

Nonoverlapping clusters: approximate distribution and application to molecular biology.

An approach is developed for the screening of genomic sequence data to identify gene regulatory regions. This approach is based on deciding if putative transcription factor binding sites are clustered together to a greater extent than one would expect by chance. Given n events occurring on an interval of width L (L base pairs), an r:w cluster is defined as r + 1 consecutive events all contained within a window of length wL. Accurate and easily computable approximations are derived for the distribution of the number of nonoverlapping r:w clusters under the model that the positions of the n events have a uniform distribution. Simulations demonstrate that these approximations have greater accuracy than existing methods. The approximation is applied to detect erythroid-specific regulatory regions in genomic DNA sequences, first in an artificial case where r is specified a priori and then as part of an exploratory approach.

Binding Sites↗
PubMed2000

Effects of agitation level on the adsorption, desorption, and activities on cotton fabrics of full length and core domains of EGV (Humicola insolens) and CenA (Cellulomonas fimi).

The activities (at pH 7 and 50 degrees C) of purified EGV (Humicola insolens) and CenA (Cellulomonas fimi) were determined on cotton fabrics at high and low levels of mechanical agitation. Similar activity measurements were also made by using the core domains of these cellulases. Activity experiments suggested that the presence of cellulose binding domains (CBDs) is not essential for cellulase performance in the textile processes, where high levels of mechanical agitation are applied. The binding reversibilities of these cellulases and their cores were studied by dilution of the treatment liquor after equilibrium adsorption. EGV showed low percentage of adsorption under both levels of agitation. It was observed that the adsorption/desorption processes of cellulases are enhanced by higher mechanical agitation levels and that the binding of cellulase with CBD of family I (EGV) is more reversible than that of CBD of the cellulase of family II (CenA).

Journal Article↗
PubMed2000

Physiological predictors of flat-water kayak performance in women.

This study was conducted to investigate the relationship between selected physiological variables and 500-m flat-water kayak (K500) performance. Nine female, high-performance kayak paddlers, mean (SD) age 23 (5) years, participated in this investigation. Testing was conducted over 6 days and included anthropometric measurements (height, body mass and skinfolds), an incremental test to determine both peak VO2 and the "anaerobic threshold" (Th(an)), and a 2-min, all-out test to calculate accumulated oxygen deficit (AOD). Blood lactate concentrations were measured during the incremental test and at the completion of both tests. Subjects also completed a K500 race under competition conditions. K500 time was significantly correlated with both peak VO2 (r = -0.82, P < 0.05) and the power output achieved at the end of the incremental test (r = -0.75, P < 0.05). However, the variable most strongly correlated with K500 time was Th(an) (r = -0.89, P < 0.05). A stepwise multiple regression, for which r = 0.95 and the standard error of estimate = 1.6 s, yielded the following equation: K500time(s) = 160.6-0.154 x AOD x kg(-1) - 0.250 x Th(an). In conclusion, the results of this study have demonstrated that although K500 performance is a predominantly aerobic activity, it does require a large anaerobic contribution. The importance of both the aerobic and anaerobic energy systems is reflected by the K500 time being best predicted by a linear combination of Th(an) and AOD x kg(-1). This suggests the need to develop and implement training programmes that develop optimally both of these physiological attributes. Further research is required to elucidate the most effective means by which to develop both the aerobic and anaerobic energy systems.

Adult↗
PubMed2000

Relationship between plasma lactate parameters and muscle characteristics in female cyclists.

PURPOSE: In a previous study, we showed that when six different plasma lactate parameters (LPs) were compared, the LP determined by the Dmax method was the best predictor of 1-h cycling performance in women. The present study extended these findings to determine whether or not the relationship between the following six LPs and endurance performance could be explained by their relationship with muscle fiber characteristics: 1) lactate threshold (LT; the power output at which plasma lactate concentration begins to increase above the resting level during an incremental exercise test), 2) LT1 (the power output at which plasma lactate increases by 1 mmol x L(-1) or more), 3) LT(D) (the lactate threshold calculated by the Dmax method), 4) LT(MOD) (the lactate threshold calculated by a modified Dmax method), 5) L4 (the power output at which plasma lactate reaches a concentration of 4 mmol x L(-1)), and 6) LT(LOG) (the power output at which plasma lactate concentration begins to increase when the log([La-]) is plotted against the log(power output)). METHODS: Twelve trained female cyclists (27.3 +/- 5.4 yr) first completed an incremental cycle test to determine both their LPs and peak VO2. One week later, endurance performance was assessed as the average absolute power output maintained during a 1-h endurance test (OHT). Resting muscle was sampled by needle biopsy from m. vastus lateralis and analyzed for fiber type diameter, fiber type percentage, 2-oxoglutarate dehydrogenase (OGDH) activity, and phosphofructokinase (PFK) activity. RESULTS: OHT performance was more strongly correlated with all LPs (r = 0.71-0.89, P < 0.05) than with peak VO2 (L x min(-1), r = 0.65, P < 0.05). OGDH activity, PFK activity, and the percentage of Type I fibers were not related to peak VO2, any of the LPs, or OHT performance. The diameter of the Type II fibers, however, was negatively related to OHT performance (r = -0.77, P < 0.01) and to four of the LPs (r = -59 to -0.86, P < 0.001). CONCLUSIONS: These correlations, which indicate that large Type II fibers may impair endurance performance, may be the result of greater production and/or reduced removal of lactate from the larger, glycolytic Type II fibers. LPs most strongly correlated with Type II fiber diameter were also most strongly correlated with OHT performance.

Adult↗
PubMed1999

The effects of strength training on endurance performance and muscle characteristics.

PURPOSE: The purpose of this study was to determine the effects of resistance training on endurance performance and selected muscle characteristics of female cyclists. METHODS: Twenty-one endurance-trained, female cyclists, aged 18-42 yr, were randomly assigned to either a resistance training (RT; N = 14) or a control group (CON; N = 7). Resistance training (2X x wk(-1)) consisted of five sets to failure (2-8 RM) of parallel squats for 12 wk. Before and immediately after the resistance-training period, all subjects completed an incremental cycle test to allow determination of both their lactate threshold (LT) and peak oxygen consumption VO2). In addition, endurance performance was assessed by average power output during a 1-h cycle test (OHT), and leg strength was measured by recording the subject's one repetition maximum (1 RM) concentric squat. Before and after the 12-wk training program, resting muscle was sampled by needle biopsy from m. vastus lateralis and analyzed for fiber type diameter, fiber type percentage, and the activities of 2-oxoglutarate dehydrogenase and phosphofructokinase. RESULTS: After the resistance training program, there was a significant increase in 1 RM concentric squat strength for RT (35.9%) but not for CON (3.7%) (P < 0.05). However, there were no significant changes in OHT performance, LT, VO2, muscle fiber characteristics, or enzyme activities in either group (P > 0.05). CONCLUSION: The present data suggest that increased leg strength does not improve cycle endurance performance in endurance-trained, female cyclists.

Adolescent↗
PubMed1999

Stages of change for increasing fruit and vegetable consumption among adults and young adults participating in the national 5-a-Day for Better Health community studies.

Higher fruit and vegetable consumption is associated with a reduced risk of certain cancers and chronic diseases. The 5-a-Day for Better Health community studies are evaluating population-based strategies to achieving dietary behavior change using the stages-of-change model and associated theories. The authors present baseline comparisons of stages of change for fruit and vegetable consumption among adults and young adults in eight study sites representing diverse regions of the United States and diverse populations and settings. Three dominant stages, precontemplation, preparation, and maintenance, were found across sites. Women and those with college degrees were more likely to be in action/maintenance. Fruit and vegetable consumption, self-efficacy, and knowledge of the 5-a-Day recommendation were positively associated with more advanced stages of change in all study sites. The authors discuss the findings in relation to possible limitations of this and other dietary stages-of-change measures and suggest directions for future research.

Adolescent↗
PubMed1999

Observations on medical device design, Part I: Current practice.

Medical devices must be designed and proven to be fit for the purpose that they were intended. Good design practice ensures this fitness for purpose and is reflected in the commercial success of products. This two-part article focuses on current industry design practice and proposes that there are significant benefits to be obtained by defining good design practice: better products and reduced development costs.

Equipment Design↗
PubMed1999

Observations on medical device design, Part II: Good practice.

Current guidance on design is inadequate. This second article in a two-part series presents a framework for good design practice that attempts to improve designers' awareness of manufacturing and validation issues. Seven design tactics, derived from observations of current industry practice and design literature, seek to encourage good practice and achieve safer, more profitable devices.

Equipment Design↗
PubMed1998

The duration of predicting trials influences time to fatigue at critical power.

The present study compared times to fatigue at CP which had been calculated from relatively long duration predicting trials. With eight recreationally active males (mean age +/- SE = 18.6 +/- 2.1 years) having first cycled to fatigue on five occasions at different fixed work rates, CP was calculated in three ways: 1. using data from the three lowest exercise intensities (CPl); 2. using data from all five exercise intensities (CPa); and 3. using data from the highest three exercise intensities (CPh). Although CP was calculated using a linear and a three-parameter non-linear model, there were insufficient suitable data to complete the latter analysis. After three days and over an eight day period, the subjects cycled for up to 60 minutes at each of the three CPs calculated using the linear model. Analysis revealed that despite high linearity with the five-point work-time regression (average r2=0.996), CPl, CPa and CPh significantly differed to each other (268 +/- 17.5W; 285 +/- 12.1W; 321 +/- 8.8W respectively; p<0.05). Significant differences were also found between times to fatigue at CPl, CPa and CPh (42.9 +/- 3.9, 39.9 +/- 4.6 and 34.4 +/- 2.7 minutes respectively; p<0.05). The data show that when CP is calculated using a linear work-time regression, time to fatigue at CP is significantly influenced by the duration of predicting trials. Moreover, exercise at CP could only be maintained for 43 minutes despite CP being calculated from predicting trials averaging between 10 and 25 minutes.

Adolescent↗
PubMed1998

The effect of stage duration on the calculation of peak VO2 during cycle ergometry.

This study investigated the influence of stage duration on the calculation of peak oxygen consumption (peak VO2 to determine whether both the lactate threshold (LT) and peak VO2 could be measured during the same test without compromising the peak VO2 value obtained. Eight moderately-active females (mean age +/- SD = 19.6 +/- 2.5 years) performed three peak VO2 tests on an electrically-braked cycle ergometer. Power output was increased every minute for the short peak VO2 test (S) and every three minutes for the long peak VO2 tests (L). Testing took place over two weeks with all tests separated by at least 48 hours. The first peak VO2 test was a long test (L1) and served as familiarisation. The subjects then performed a short (S) and a long (L2) peak VO2 test in random, counterbalanced order. For each subject, all three tests were performed at the same time of day in controlled environmental conditions. There was no significant difference between the two exercise protocols for peak VO2 when expressed in ml x kg(-1) x min(-1) (F[1,7]=3.47, P=0.105) or in L x min(-1) (F[1,7]=3.39. P=0.108). However, the maximum heart rate (HRmax) achieved in S was significantly less than the HRmax achieved in L2 (F[1,7]=33.4, P<0.001). The power output at exhaustion (Wpeak) was significantly greater in S than in L2 (F[1,7]=56.5, P<0.001). The data from this study therefore showed that in moderately-active females, a three-minute incremental protocol, allowing for the simultaneous calculation of the LT, could be used without compromising peak VO2, but that HRmax and Wpeak were affected.

Adolescent↗
PubMed1998

The critical power function is dependent on the duration of the predictive exercise tests chosen.

The linear relationship between work accomplished (W(lim)) and time to exhaustion (t(lim)) can be described by the equation: W(lim) = a + CP x t(lim). Critical power (CP) is the slope of this line and is thought to represent a maximum rate of ATP synthesis without exhaustion, presumably an inherent characteristic of the aerobic energy system. The present investigation determined whether the choice of predictive tests would elicit significant differences in the estimated CP. Ten female physical education students completed, in random order and on consecutive days, five all-out predictive tests at preselected constant-power outputs. Predictive tests were performed on an electrically-braked cycle ergometer and power loadings were individually chosen so as to induce fatigue within approximately 1-10 mins. CP was derived by fitting the linear W(lim)-t(lim) regression and calculated three ways: 1) using the first, third and fifth W(lim)-t(lim) coordinates (I135), 2) using coordinates from the three highest power outputs (I123; mean t(lim) = 68-193 s) and 3) using coordinates from the lowest power outputs (I345; mean t(lim) = 193-485 s). Repeated measures ANOVA revealed that CPI123 (201.0+/-37.9W) > CPI135 (176.1+/-27.6W) > CPI345 (164.0+/-22.8W) (P<0.05). When the three sets of data were used to fit the hyperbolic Power-t(lim) regression, statistically significant differences between each CP were also found (P<0.05). The shorter the predictive trials, the greater the slope of the W(lim)-t(lim) regression; possibly because of the greater influence of 'aerobic inertia' on these trials. This may explain why CP has failed to represent a maximal, sustainable work rate. The present findings suggest that if CP is to represent the highest power output that an individual can maintain "for a very long time without fatigue" then CP should be calculated over a range of predictive tests in which the influence of aerobic inertia is minimised.

Adenosine Triphosphate↗
PubMed1998

The relationship between plasma lactate parameters, Wpeak and 1-h cycling performance in women.

PURPOSE: The relationship between six descriptors of lactate increase, peak VO2, Wpeak, and 1-h cycling performance were compared in 24 trained, female cyclists (peak VO(2) = 48.11 +/- 6.32 mLxkg(-1)xmin(-1). METHODS: The six descriptors of lactate increase were: 1) lactate threshold (LT; the power output at which plasma lactate concentration begins to increase above the resting level during an incremental exercise test), 2) LT(1) the power output at which plasma lactate increases by 1 mM or more), 3) LT(D) (the lactate threshold calculated by the D-max method), 4) LT(MOD) (the lactate threshold calculated by a modified D-max method), 5) L4 (the power output at which plasma lactate reaches a concentration of 4 mmolxL(-1), and 6) LT(LOG) (the power output at which plasma lactate concentration begins to increase when the log ([La(-1]) is plotted against the log (power output). Subjects first completed a peak VO(2) test on a cycle ergometer. Finger-tip capillary blood was sampled within 30 s of the end of each 3-min stage for analysis of plasma lactate. Endurance performance was assessed 7 d later using a 1-h cycle test (OHT) in which subjects were directed to achieve the highest possible average power output. RESULTS: The mean power output (W) for the OHT (+/- SD) was 183.01 +/- 18.88, and for each lactate variable was:LT (138.54 +/- 46.61), LT(1) (179.17 +/- 27.25), LT(log) (143.97 +/- 45.74), L4 (198.09 +/- 33.84), LT(D) (178.79 +/- 24.07), LT(MOD)(212.28 +/- 31.75). Average power output during the OHT was more strongly correlated with all plasma lactate parameters (0.61<r<0.84) and W(peak) (r = 0.81) than with peak VO(2) (r = 0.55). The six lactate parameters were strongly correlated with each other (0.54<r<0.91) and of six lactate parameters, LT(D) correlated best with endurance performance (r = 0.84). CONCLUSIONS: It was concluded that plasma lactate parameters and W(peak) provide better indices of endurance performance than peak VO(2) and that, of the six descriptors of lactate increase measured in this study, LT(D) is most strongly related to 1-h cycling performance in trained, female cyclists.

Adult↗
PubMed1998

Membrane organization of bluetongue virus nonstructural glycoprotein NS3.

The smallest RNA segment (S10) of bluetongue virus (an orbivirus, family Reoviridae) encodes two closely related nonstructural proteins, the 229-amino-acid (aa) NS3 and the 216-aa NS3A. The proteins are found in glycosylated and nonglycosylated forms in infected cells (X. Wu, H. Iwata, S.-Y. Chen, R. W. Compans and P. Roy J. Virol. 66:7104-7112, 1992). The NS3/NS3A proteins have two hydrophobic domains (aa 118 to 141 and 162 to 182) and two potential asparagine-linked glycosylation sites (aa 63 and 150), one of which is located between the hydrophobic domains. To determine whether these features were used in the mature protein forms, we generated a series of mutants of the S10 gene and expressed them by using the vaccinia virus T7 polymerase transient-expression system. Our data indicate that both hydrophobic domains of NS3 span the cell membrane and that only the site at aa 150 is responsible for N-linked glycosylation of the NS3 proteins.

Amino Acid Sequence↗
PubMed1997

The use of lidocaine in microvascular reconstruction.

Vasospasm is known to have an adverse effect on the survival of free tissue transfers. Prolonged vasoconstriction decreases blood flow to the flap and promotes thrombosis at the anastomotic site. Because of its wide availability and rapid effect, topically applied lidocaine is used by many surgeons to prevent and correct vasospasm. Mucosal absorption of lidocaine is known to be rapid. Absorption by the surgical bed during microvascular reconstruction has not previously been determined. We had three specific aims: (1) to determine whether systemic absorption occurs, (2) if so, to determine the degree of absorption, and (3) to determine whether the type of reconstruction affects the degree of absorption. Twelve consecutive patients were entered into the study, four in a myocutaneous reconstructive group and eight in a fasciocutaneous group. Baseline serum lidocaine levels were drawn. After the initial application of lidocaine, levels were drawn every 30 minutes. Final levels were drawn 120 minutes after the last application. The total amount of lidocaine used ranged from 720 mg to 2600 mg. Application ranged from 7.5 mg/minute to 34.7 mg/minute (2 to 9 times the estimated toxic dose of 4 mg/minute for a patient weighing 70 kg). Results ranged from undetectable (<0.5 microg/ml) to minimal therapeutic levels (1.6 microg/ml). Toxic levels (>6.0 microg/ml) were not encountered. Significant (p < 0.05) differences were found between the fasciocutaneous group, which generally had no detectable serum levels, and the myocutaneous group, which had detectable subtherapeutic to minimally therapeutic levels. Doses considered toxic by intravenous or mucous membrane application may safely be applied topically. Greater absorption was found in the myocutaneous group, which is believed to be a result of the richer absorption surface provided by the muscular tissue.

Absorption↗