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PubMed1989

Sensitivity and detection efficiency of the peroxidase antiperoxidase (PAP), avidin-biotin peroxidase complex (ABC), and peroxidase-labeled avidin-biotin (LAB) methods.

The authors have examined the sensitivity and detection efficiency of the three peroxidase methods that currently have the widest application in diagnostic immunohistochemistry: the peroxidase-antiperoxidase (PAP), the avidin-biotin complex (ABC), and the labeled avidin-biotin (LAB) methods. Sensitivity was evaluated by determining the highest useful dilution of polyclonal antiglucagon antibodies applied to formalin-fixed, paraffin-embedded human pancreas. Detection efficiency was evaluated by tabulation of the total number of positive (three or more positive cells) islets. On direct comparison, the LAB method exceeded the PAP and ABC methods in both sensitivity and detection efficiency, which were essentially equal. Titration of linking antiserum of the PAP method boosted its sensitivity and detection efficiency above that of ABC; the PAP had equal sensitivity to the LAB and exceeded it in detection efficiency. The authors conclude that comparisons of immunohistologic methods are meaningful only if both sensitivity and efficiency are considered along with the unique requirements of any single method.

Avidin↗

PubMed1985

The efficiency of measles and pertussis notification in England and Wales.

This paper examines methods for estimating the efficiency of measles and pertussis notification with particular reference to England and Wales. Crude estimates are obtained from a comparison of annual numbers of births and notifications, and this approach is modified to include detailed age-specific data. Other sources of data, notably the Hospital In-Patient Enquiry, are used to give detailed estimates over time. These analyses provide evidence for a strong positive correlation between notification efficiency and incidence for both diseases and for a dramatic fall in the notification efficiency for pertussis between 1957 and 1976. This decrease is of particular interest insofar as it could explain in part the apparent fall in size of successive pertussis epidemics during that period. It is estimated that since 1976 the spotter practices of the Royal College of General Practitioners General Practice Research Unit have been approximately 1.5 times more efficient at reporting measles and 2.5 times more efficient at reporting pertussis than the national average for reporting to the Office of Population Censuses and Surveys. Finally it is noted that estimates of notification efficiency are positively correlated with the assumed level of vaccine efficacy, and that all these methods require assumptions concerning the proportion of vaccinations which are recorded, the proportion of vaccinations which are successful in immunizing the recipient, and the proportion of the population which ultimately contracts the infection. In general, measles notification in England and Wales is considerably better than that for pertussis, being of the order of 40-60% for the former and only 5-25% for the latter.

Child↗

PubMed1975

Influence of genetic differences in feed efficiency on carcass composition of young chickens.

The carcass composition of young chickens differing in efficiency of feed utilization was obtained to study changes in the carcass composition associated with differences in efficiency of feed utilization. As the efficiency of conversion of food to tissue was changed, there were associated changes in carcass moisture and lipid, regardless of differences between different populations in variability for growth rate. Carcass moisture was increased and carcass lipid was decreased in chickens with relatively better conversion of food into carcass. Carcass protein was significantly increased in chickens with better efficiency of feed utilization in one population, but not in another. Changes in carcass composition associated with efficiency of feed utilization were similar regardless of whether differences in efficiency were due to gain or to a combination of gain and consumption. Significant sex differences in carcass moisture, lipid, and protein were observed in the faster-growing broiler population but not in the lines selected from a slower-growing randombred population. There was a significant decrease in 16:1 and an increase in 18:0 fatty acids of chickens with a lower feed conversion ratio.

Adipose Tissue↗

PubMed1976

Maintenance requirement and energetic efficiency of lean and obese Zucker rats.

The body balance technique was used to determine the maintenance requirement and the energetic efficiency of 6-week-old male lean and obese Zucker rats. Fifteen lean and 15 obese rats were assigned to three groups of five each and fed three levels of food intake: ad libitum, 75% of ad libitum, and 50% of ad libitum, for a 4-week period. The obese rats consumed more food and gained significantly more weight than the lean rats. Obese rats utilized dietary energy more efficiently than lean rats but the opposite was true for dietary protein. The efficiency with which obese rats utilized metabolizable energy for gain was 36% compared with efficiency of utilization of metabolizable energy above maintenance for obese and lean were 51.4% and 21.4%, respectively. The maintenance requirement on the basis of metabolic body size for the obese and lean was calculated to be 122 and 130.5 kcal ME per day per kg.75 for the 4-week period. These results indicate that the energetic efficiency is higher in obese than in lean Zucker rats and suggest that the higher energetic efficiency is not the result of a significantly lower maintenance requirement.

Animals↗

PubMed1991

Opposite effect of cold on energetic efficiency in normal and obese Wistar rats with hypothalamic lesions.

Reduced thermogenesis in brown adipose tissue (BAT) may contribute to increased energetic efficiency and obesity in rats with ventromedial hypothalamic (VMH) lesions. Thermogenic activity of BAT is a function of the environmental temperature. If a relationship exists, it follows that the increased energetic efficiency of VMH-lesioned rats likewise should be governed by temperature. We have therefore investigated the energy balance of normal and VMH-lesioned rats housed at 30 degrees C and 10 degrees C. Experiments at differing feeding levels allowed calculation of maintenance energy requirements and the net energetic efficiencies of each group. VMH-lesioned rats at thermoneutrality (30 degrees C) accumulated more body fat at all feeding levels than did normal rats. Maintenance energy requirement was reduced, but the net energetic efficiency did not differ significantly from normal. The reduced maintenance energy requirement of lesioned rats persisted at 10 degrees C. Net energetic efficiency decreased in normal rats acclimated to cold but increased in the lesioned group. The difference was significant (P less than 0.05). The cold-induced increase in interscapular brown adipose tissue (IBAT) oxidative capacity of VMH-lesioned rats was only half that of normal rats. Differences in BAT thermogenesis may be the basis for the differing temperature effects on net energetic efficiency.

Adipose Tissue↗

PubMed1995

Chronic protein restriction does not alter energetic efficiency or brown adipose tissue thermogenic capacity in genetically obese (fa/fa) Zucker rats.

Attenuated regulatory thermogenesis in genetically obese (fa/fa) Zucker rats involves an impaired capacity to increase sympathetic drive to brown adipose tissue in response to dietary stimuli. Young, growing lean rats fed a low protein diet reduce energetic efficiency to compensate for elevated energy intake; however, it is not known if obese rats adapt similarly to chronic protein restriction by decreasing energetic efficiency and whether this would be accompanied by increased brown adipose tissue thermogenic capacity. Lean (Fa/Fa) and obese Zucker rats were either protein-restricted (protein 8% of total energy) or fed a control diet (21% protein) starting at age 5 wk. At 9 wk, oxygen consumption (VO2) was measured in response to an intubated meal of mixed macronutrient composition. Mass-adjusted food intake (i.e., food intake/body weight 0.67) was greater in protein-restricted than in control lean rats, but not different due to diet in obese rats. Mass-adjusted brown adipose tissue uncoupling protein levels were more than 100% greater in protein-restricted vs. control lean rats, but not different between protein-restricted and control obese rats. The uncoupling protein level was not significantly different in control lean vs. obese rats. Energetic efficiency was 40% lower in protein-restricted vs. control lean, but not different in obese rats; however, the efficiency of protein utilization was significantly greater in obese protein-restricted than in obese control rats. Meal-induced energy expenditure (VO2) did not differ significantly due to diet or genotype. In conclusion, protein restriction led to overfeeding in lean rats which appeared to enhance brown adipose tissue thermogenic capacity and decrease energetic efficiency. Protein efficiency increased to more than two times its original value in obese (fa/fa) rats, but otherwise no metabolic accommodation in the capacity for regulatory thermogenesis was observed in this genotype.

Adipose Tissue↗

PubMed2004

Agronomic options for improving rainfall-use efficiency of crops in dryland farming systems.

Yields of dryland (rainfed) wheat in Australia have increased steadily over the past century despite rainfall being unchanged, indicating that the rainfall-use efficiency has increased. Analyses suggest that at least half of the increase in rainfall-use efficiency can be attributed to improved agronomic management. Various methods of analysing the factors influencing dryland yields and rainfall-use efficiency, such as simple rules and more complex models, are presented and the agronomic factors influencing water use, water-use efficiency, and harvest index of crops are discussed. The adoption of agronomic procedures such as minimum tillage, appropriate fertilizer use, improved weed/disease/insect control, timely planting, and a range of rotation options, in conjunction with new cultivars, has the potential to increase the yields and rainfall-use efficiency of dryland crops. It is concluded that most of the agronomic options for improving rainfall-use efficiency in rainfed agricultural systems decrease water losses by soil evaporation, runoff, throughflow, deep drainage, and competing weeds, thereby making more water available for increased water use by the crop.

Agriculture↗

PubMed1988

In vitro transcription and translational efficiency of chimeric SP6 messenger RNAs devoid of 5' vector nucleotides.

A plasmid containing the bacteriophage SP6 promoter, designated pHSTO, permits in vitro transcription of RNAs devoid of vector-derived nucleotides. This vector has been characterized for relative transcriptional activity using constructs which alter the conserved nucleotides extending beyond the SP6 transcriptional initiation site. SP6 polymerase efficiently transcribes cDNA inserts which contain a guanosine (G) nucleotide at position +1 relative to the SP6 promoter; however, inserts with an adenosine (A) or pyrimidine at position +1 are not transcribed. Several cellular and viral cDNAs have been transcribed into translatable messenger RNA using this vector; however, SP6 polymerase will not transcribe the A-T rich untranslated leader from alfalfa mosaic virus RNA 4 efficiently unless the viral mRNA cap site is separated from the transcriptional initiation site by twelve base pairs of vector DNA. Chimeric messenger RNAs were created by linking the untranslated leader sequence of several viral mRNAs to the coding region of barley alpha-amylase, and the resultant mRNAs were translated in a wheat germ extract to determine relative translational efficiencies. The untranslated leader sequences of turnip yellow mosaic virus coat protein mRNA and black beetle virus RNA 2 did not increase translational efficiency, while the tobacco mosaic virus leader stimulated translation significantly. The results indicate that substitution of a cognate untranslated leader sequence with a leader derived from a highly efficient mRNA does not necessarily predict enhanced translational efficiency of the chimeric mRNA.

Bacteriophages↗

PubMed2001

Optimal conditions to use Pfu exo(-) DNA polymerase for highly efficient ligation-mediated polymerase chain reaction protocols.

Ligation-Mediated Polymerase Chain Reaction (LMPCR) is the most sensitive sequencing technique available to map single-stranded DNA breaks at the nucleotide level of resolution using genomic DNA. LMPCR has been adapted to map DNA damage and reveal DNA-protein interactions inside living cells. However, the sequence context (GC content), the global break frequency and the current combination of DNA polymerases used in LMPCR affect the quality of the results. In this study, we developed and optimized an LMPCR protocol adapted for Pyrococcus furiosus exo(-) DNA polymerase (Pfu exo(-)). The relative efficiency of Pfu exo(-) was compared to T7-modified DNA polymerase (Sequenase 2.0) at the primer extension step and to Thermus aquaticus DNA polymerase (Taq) at the PCR amplification step of LMPCR. At all break frequencies tested, Pfu exo(-) proved to be more efficient than Sequenase 2.0. During both primer extension and PCR amplification steps, the ratio of DNA molecules per unit of DNA polymerase was the main determinant of the efficiency of Pfu exo(-), while the efficiency of Taq was less affected by this ratio. Substitution of NaCl for KCl in the PCR reaction buffer of Taq strikingly improved the efficiency of the DNA polymerase. Pfu exo(-) was clearly more efficient than Taq to specifically amplify extremely GC-rich genomic DNA sequences. Our results show that a combination of Pfu exo(-) at the primer extension step and Taq at the PCR amplification step is ideal for in vivo DNA analysis and DNA damage mapping using LMPCR.

Base Sequence↗

PubMed2026

Target site selection and P1 engineering enable highly efficient circular RNA production via end-to-end self-targeting and splicing.

Circular RNAs (circRNAs) are more stable than linear RNAs, enabling expanding applications in RNA vaccines and therapeutics. We previously developed an in vitro circRNA preparation method based on end-to-end self-targeting and splicing (STS) using the Tetrahymena group I intron, which generates circRNAs without extraneous sequences. However, self-circularization efficiency declines as gene of interest (GOI) length increases, limiting its application to longer GOIs. Here, we systematically optimized key determinants of STS efficiency, including target site selection and P1 construct engineering. Target site screening revealed that selection of optimal target sites within each GOI markedly improved self-circularization efficiency. Moreover, engineering of the P1 construct, including incorporation of a polyA10 sequence upstream of the internal guide sequence of the intron and an antisense sequence complementary to the target site and its upstream region at the 5' side of polyA10, further enhanced efficiency. Notably, the optimized STS strategy achieved up to two-fold higher self-circularization efficiency than the conventional permuted intron-exon (PIE) method for long GOIs (∼8 K-nt). Collectively, these results establish an improved STS workflow for efficient circRNA production without extraneous sequences across a wide range of GOI lengths, outperforming the PIE method for long GOIs, and broadening biomedical applications.

RNA, Circular↗

PubMed2002

Pseudomonas putida strain PCL1444, selected for efficient root colonization and naphthalene degradation, effectively utilizes root exudate components.

Previously, we have described the selection of a plant-bacterium pair that is efficient in rhizoremediating naphthalene pollution in microcosm studies. After repeated selection for efficient root tip colonization upon inoculation of seeds of grass cv. Barmultra and for stable and efficient growth on naphthalene, Pseudomonas putida PCL1444 was selected as the most efficient colonizer of Barmultra roots. Here, we report the analysis of Barmultra root exudate composition and our subsequent tests of the growth rate of the bacterium and of the expression of the naphthalene degradation genes on individual exudate components. High performance liquid chromatography analysis of the organic acid and sugar root-exudate components revealed that glucose and fructose are the most abundant sugars, whereas succinic acid and citric acid are the most abundant organic acids. Tn5luxAB mutants of PCL1444 impaired in naphthalene degradation appeared to be impaired in genes homologous to genes of the upper naphthalene degradation pathway present in various Pseudomonas strains and to genes of the lower pathway genes for naphthalene degradation in P. stutzeri. Highest expression for both pathways involved in naphthalene degradation during growth in minimal medium with the carbon source to be tested was observed at the start of the logarithmic phase. Naphthalene did not induce the upper pathway, but a different pattern of expression was observed in the lower pathway reporter, probably due to the conversion of naphthalene to salicylic acid. Salicylic acid, which is described as an intermediate of the naphthalene degradation pathway in many Pseudomonas strains, did induce both pathways, resulting in an up to sixfold higher expression level at the start of the logarithmic phase. When expression levels during growth on the different carbon sources present in root exudate were compared, highest expression was observed on the two major root exudate components, glucose and succinic acid. These results show an excellent correlation between successful naphthalene rhizoremediation by the Barmultra-P. putida PCL1444 pair and both efficient utilization of the major exudate components for growth and high transcription of the naphthalene catabolic genes on the major exudate components. Therefore, we hypothesize that efficient root colonizing and naphthalene degradation is the result of the applied colonization enrichment procedure.

Carbon↗

PubMed1994

Effectiveness and efficiency of a Dutch pediatric intensive care unit: validity and application of the Pediatric Risk of Mortality score.

OBJECTIVE: To assess the performance of pediatric intensive care by an international standard. DESIGN: Prospective, cohort study. SETTING: Nine-bed multidisciplinary pediatric intensive care unit (ICU) within a 174-bed, tertiary care children's hospital. PATIENTS: Consecutive, unselected patients (n = 612) during a 16-month period. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Collected data included age, major diagnostic category, primary clinical specialty, severity of illness (daily Pediatric Risk of Mortality [PRISM] score), administration of ICU-dependent therapy (daily), and vital status at discharge. The PRISM score allowed the calculation of overall and daily mortality risk. After testing the applicability of the predictive model, effectiveness was determined by comparing severity of illness-based predicted mortality rate with vital status at discharge. Efficiency was defined by two criteria: a) the administration of at least one ICU-dependent therapy; or b) a mortality risk of > 1%. Five-hundred ninety-three patients were included (19 survivors were excluded because of incomplete data). Mean age was 55.0 months (median 24). Mean length of stay was 4.4 days (median 2). Overall ICU mortality rate was 8.4%. The overall performance of the PRISM score-based predictive model was found to be good (goodness-of-fit test chi 2[5] = 5.49; p = .35; area under receiver operating characteristic curve 0.92). Subgroup analysis showed that the best model performance was in nonoperative patients. Decreased performance was found in operative patients. In cardiovascular patients, the mortality rate was higher. In other surgical patients, the mortality rate was lower than expected. Of 593 patients, 489 (82.5%) admissions were efficient, as were 2,393 (76.5%) of 3,130 patient days in the ICU. The ranking of daily efficiency according to clinical specialty was as follows: postoperative cardiovascular surgical patients (86.3%); nonsurgical patients (76.6%); and other postoperative patients (49.6%). CONCLUSIONS: In our setting, effectiveness and efficiency of pediatric intensive care appeared to be validly determined using explicit criteria (mortality risk, administration of ICU-dependent therapy). Overall effectiveness met the standard set forth in an American study; validity in stratified analysis of diagnostic subgroups remains to be further established. Efficiency showed marked, specialty-related differences. The low efficiency in other (noncardiovascular) surgical patients was probably caused by the recovery function of the ICU. A more general application of these criteria might be considered in modifying admission and discharge policy, as well as in quality control.

Child↗

PubMed1989

Improved counting efficiencies for measuring 239Pu in the lung in the sitting position.

For a study sponsored by the International Atomic Energy Agency (IAEA), Pacific Northwest Laboratory (PNL) made lung counting measurements of lung deposition in 10 women who had inhaled 92mNb in England. These women were measured in both the supine and sitting (torso 45 degrees from horizontal) positions with a counting system of Ge planar detectors and another counting system of Phoswich detectors. The average increase in counting efficiency from the supine to the sitting position was 108% for the Ge detectors and 310% for the Phoswich detectors. Individual counting efficiency increases ranged from 15-260% for the Ge detectors and from 40-480% for the Phoswich detectors. The increase in counting efficiency was roughly proportional to the total chest wall thickness of the measured individuals. By using the equivalent muscle tissue thickness of the individual's chest wall, the increase in counting efficiency could be attributed to the decrease in the tissue absorption in the sitting position. The decreased distance between the lungs and the detector achieved in the sitting positions may also account for some of the improvement in counting efficiency. In addition, some undetermined internal change in activity distribution (source-to-detector geometry) and tissue absorption may possibly contribute to the improved counting efficiency of the sitting vs. the supine position.

Environmental Exposure↗

PubMed1992

Determining the collection efficiency of gummed paper for the deposition of radioactive contaminants in simulated rain.

An extensive network of gummed paper collectors was used during the 1950s for routine monitoring of radioactive fallout from weapons testing. The experiments reported in this paper were designed to examine the collection efficiency of gummed paper for wet deposition of several types of soluble and insoluble radioactive contaminants under conditions similar to those found during natural rainstorms. The collection efficiencies for each substance were determined over a range of rainfall amounts and at two separate rainfall intensities. The collection efficiency of the gummed paper is highest for large insoluble particles and lowest for soluble ionic substances. The values for 7Be and 131I ranged from about 0.30 (30%) at 2.5 mm of rain to 0.04-0.06 (4%-6%) at 20 mm of rain. These values were negatively correlated with the amount of rain and were unaffected by rain intensity. This suggests that the collection efficiency of either ion is simply a matter of rapid saturation and runoff. Neither rain amount nor rain intensity has much effect on the collection efficiency of large insoluble particles. These particles seem to settle readily onto the surface of the gummed paper from which they are not easily removed by additional rain. Analysis of the collection efficiencies of the gummed paper included the activity of both the gummed paper and the standing water on the paper. A large portion of the activity for the ionic substances was found in the standing water. There was less activity by insoluble particles in standing water. This indicates that for estimates of deposition of soluble substances, considerable bias could be introduced into the results if the standing water is discarded prior to analysis.

Adhesives↗

PubMed1997

Ambient air sampling for tritium--determination of breakthrough volumes and collection efficiencies for silica gel adsorbent.

Ambient air samples for tritium (as HTO) can be collected using the solid adsorbent silica gel. The purpose of this study was to determine the maximum practical sampling volume and overall collection efficiency for water vapor collected on silica gel columns and to demonstrate the use of an impinger-based system to load water vapor onto silica gel columns. Breakthrough volumes (Vb) were measured and chromatographic efficiencies (expressed as the number of theoretical plates, N) were calculated for a 20 degrees C to 50 degrees C temperature range, with the relative humidity at approximately 30%. The tests yielded relative breakthrough volumes (air volume/adsorbent depth, m3 cm(-1)) of 0.36 for 20 degrees C, 0.20 for 30 degrees C, 0.15 for 40 degrees C, and 0.077 for 50 degrees C. For 18-cm columns, the average tritium tracer recoveries at 20 degrees C were 71% with no observed breakthrough for air volumes up to 5 m3, while at 40 degrees C mean tritium tracer recoveries dropped from 75% for volumes < or = 3.0 m3, to 0% for a volume of 5.0 m3. Frontal chromatographic profiles were measured for water vapor migrating through silica gel columns that were divided into 5 segments. The chromatographic efficiency of the silica gel columns was determined by graphical evaluation of the chromatography profiles. At a sampling rate of 0.25 L min(-1) and 30% relative humidity, the number of theoretical plates per adsorbent depth were 0.55 N cm(-1) at 20 degrees C, 0.68 N cm(-1) at 30 degrees C, 0.51 N cm(-1) at 40 degrees C, and 0.30 N cm(-1) at 50 degrees C. Chromatographic theory was used to estimate the overall collection efficiency of the silica gel columns as a function of the ratio of the sampling volume to breakthrough volume and the chromatographic efficiency. For a 9.5 m3 sample volume, 30% relative humidity, 0.25 L min(-1) sampling rate, and a 54-cm column, the overall collection efficiency was above 99.9% at 20 degrees C, above 95% at 30 degrees C, just below 80% at 40 degrees C, and <<80% at 50 degrees C.

Adsorption↗

PubMed1989

The impact of prospective reimbursement on nursing home efficiency.

Data Envelopment Analysis (DEA) was used to estimate the relative efficiencies of nursing homes in Maine for 2 years before the introduction of a prospective payment system and for 2 years afterward. A multiple regression was performed in which the DEA-estimated efficiency was the dependent variable and a number of facility characteristics and study year were the independent variables. Study findings indicate that nursing home efficiency scores fell after the introduction of prospective reimbursement; that is, generally speaking, more inputs were being used per unit of output in the period after the introduction of prospective reimbursement than in the period preceding it. This may be the result of poor management, degraded quality of inputs, improved quality of outputs, or some other unobserved trend during this same period. The study also concludes that higher occupancy rates are associated with lower efficiencies and that patients in restraints produce severe negative effects on efficiency. In addition, it appears that a sudden increase in administrative hours in the final study year played a role in that year's lower average efficiency scores, but also that all input levels generally rose while output levels remained virtually constant.

Bed Occupancy↗

PubMed2000

Effect of cadence, cycling experience, and aerobic power on delta efficiency during cycling.

PURPOSE: To examine the influence of cadence, cycling experience, and aerobic power on delta efficiency during cycling and to determine the significance of delta efficiency as a factor underlying the selection of preferred cadence. METHODS: Delta efficiency (DE) was determined for 11 trained experienced cyclists (C), 10 trained runners (R), and 10 less-trained noncyclists (LT) at 50, 65, 80, 95, and 110 rpm. Preferred cadence (PC) was determined at 100, 150, and 200 W for C and R and at 75, 100, and 150 W for LT. Gas exchange at each power output (PO) was measured on a separate day, and the five cadences were randomly ordered on each occasion. It was hypothesized that: a) cyclists are most efficient at the higher cadences at which they are accustomed to training and racing, i.e., there will be a trend for DE to increase with increases in cadence; b) cyclists and runners will exhibit similar DE across the range of cadences tested; and c) DE of less-trained subjects will be lower than that of cyclists and runners. RESULTS: PCs of C and R were similar and did not change appreciably with PO (100 W:C, 95.6 +/- 10.8; R, 92.0 +/- 8.5: 150 W:C, 94.4 +/- 10.3; R, 92.9 +/- 7.8: 200 W:C, 92.2 +/- 7.2; R, 91.8 +/- 7.9 rpm). The PC of LT was significantly lower and decreased with increases in power output (75 W: 80.0 +/- 15.3; 100 W; 77.5 +/- 15.1; 150 W; 69.1 +/- 11.9 rpm). The first hypothesis was rejected because analysis of the cyclists' data alone revealed no systematic increase in DE as cadence was increased [F(4,40) = 0.272, P = 0.894]. Repeated measures ANOVA on all three groups revealed no group x cadence interaction [F(8,112) = 0.589, P = 0.785]. Again there was no systematic effect of cadence on DE [F(4,112) = 1.058, P = 0.381]. The second and third hypotheses were also rejected since there was no group main effect, i.e., DE of cyclists, runners, and less-trained subjects were not significantly different [F(2,28) = 1.397, P = 0.264]. CONCLUSION: Pedaling cadence did not have a dramatic effect on DE in any group. Muscular efficiency, as measured indirectly by delta efficiency, appears to remain relatively constant at approximately 24%, regardless of cycling experience or fitness level.

Adult↗

PubMed2000

Changes in cycling efficiency and performance after endurance exercise.

PURPOSE: This study was designed to examine the effects of moderate-intensity endurance exercise on cycling performance, gross efficiency, and 30-s sprint power output. METHODS: Two separate experiments were conducted. After a controlled warm-up, subjects completed as much work as possible in a 5-min performance test (EXP1) or a maximal 30-s sprint test (EXP2). These initial exercise bouts were followed by approximately 60 min of cycling at approximately 60% VO2peak or an equivalent period of rest (control) before repeating the warm-up exercise and either the 5-min performance or 30-s sprint test. Expired gas for calculation of cycling gross efficiency was collected over the last minute of each warm-up period. RESULTS: Average 5-min performance power output was significantly reduced (12 W) after exercise in EXP1, and in EXP2 both peak and mean power output were significantly lower (26 and 35 W, respectively). Gross efficiency decreased significantly with exercise in both EXP1 and EXP2. Moreover, the change in gross efficiency was correlated with the change in 5-min performance (r = 0.91, P < 0.01), but not with the change in mean or peak 30-s sprint power output. CONCLUSIONS: After sustained moderate-intensity cycling significant reductions in 5-min performance, gross efficiency and sprint power output were observed in endurance trained cyclists. The reduction in 5-min performance was related to the exercise induced decrease in gross efficiency.

Bicycling↗