bluuebunny/crossref_metadata_2025 huggingface dataset:
THE ACID‐BASE AND ELECTROLYTE PATTERN IN THE ERYTHROBLASTOTIC INFANT AND ITS RELATIONSHIP TO VARIOUS PARAMETERS DURING EXCHANGE TRANSFUSION
Authors: MAGUIRE HERBERT , KRETZSCHMAR GÜNTER , WALLGREN GÖRAN
Published: January 2008

The effect of exchange transfusion in the electrolyte and acid‐base balance has been studied in 37 newborn infants undergoing the procedure because of hyperbilirubinemia. Particular interest was focused on possible relationships between induced changes and various pertinent parameters such as infant and donor blood characteristics and rate and volume of the exchange. A statistically highly significant decrease in pH and plasma bicarbonate was noted together with a decrease of the potassium level. Changes in other electrolytes were inconsistent. There was a highly significant correlation between rate of exchange and acid‐base disturbance as well as between induced potassium decrease and the total volume of the procedure. There was no demonstrable increase of the susceptibility to induced changes among the low‐weight infants. A recovery period of 20 minutes was usually sufficient to allow for the control of the metabolic derangement and in some instances an alkalotic overshoot was encountered as related to the preoperative control value. The potassium level continued to fall during the recovery period.

The technical aspects of the procedure are discussed against the reported findings.
Effect of two forest grasses differing in their growth dynamics on the water relations and the growth of Quercus petraea seedlings
Authors: Collet Catherine , Frochot Henri , Guehl Jean-Marc , Ferhi André
Published: January 2008

Interference between 1-year-old sessile oak (Quercus petraea (Mattus.) Liebl.) seedlings and two grass species (Agrostis stolonifera L. and Deschampsia cespitosa (L.) Beauv.) was evaluated during 3 years after seedling transplantation. The seedlings were grown in large containers under crossed levels of watering regimes (regular irrigation that maintained the soil at field capacity or seasonal water stress) and grass competition (with Agrostis, Deschampsia, or bare soil). After 3 years, seedling basal diameter was 2.5 times greater in the absence of competing vegetation than with one of the two grasses. Within the grass-competition treatments, diameter was 1.3 times as great for the seedlings grown in the irrigated treatments than for the seedlings grown in the water-stressed treatments and was 1.3 times greater for the seedlings grown with Agrostis than for the seedlings grown with Deschampsia. During the first 2 years, the seedlings grew much faster in the bare soil than in the weedy treatments, whatever the watering level. During the 3rd year, the seedlings in all the irrigated treatments showed similar relative growth rate values, which were much higher than those in the water-stressed treatments. Each year, soil water potential reached −2.5 MPa under the two grasses and −0.7 MPa under bare soil by the end of summer. On the contrary, competition for nutrients seemed to be low. Assessments of plant carbon isotope composition showed that the seedlings in the weedy water-stressed treatments had higher intrinsic water-use efficiency, and also suggested that the competition exerted by the two grasses occurred mainly for water. We conclude that during the first 2 years, the negative effects of the two grass species on seedling growth seemed to be largely independent of any competition for water. Conversely, during the 3rd year, the influence of the grasses on the seedlings seemed to be related only to competition for water. Keywords: root interactions, water stress, osmotic adjustment, carbon isotope discrimination, classical growth analysis.
Community structure of ectomycorrhizal fungi in a Pinus muricata forest: above- and below-ground views
Authors: Gardes M. , Bruns T. D.
Published: January 2008

We examined the species diversity of an ectomycorrhizal community in natural stands of bishop pine (Pinus muricata D. Don) to determine the correspondence between above- and below-ground views of species composition, spatial frequency, and abundance. We addressed this question by simultaneously sampling fruit bodies and ectomycorrhizae over a 4-year period. By using molecular methods based on polymerase chain reaction, we were able to identify the fungal symbionts directly from mycorrhizae in nearly all of the mycorrhizal morphotypes we found. Most species were either rare or low in abundance. Among the common species we observed three patterns: (i) some species, such as Russula xerampelina s.l. and Amanita francheti were well represented both above- and below-ground; (ii) some common fruiting species such as Suillus pungens were rare components belowground; (iii) some species that were common as mycorrhizae were represented poorly or unrepresented in the aboveground fruiting record. The latter was the case for Russula amoenolens, thelephoroid types (i.e., Tomentella sublilacina and thelephoroid-2), and a boletoid type. These results show that (i) the pattern of resource allocation to production of fruit bodies versus ectomycorrhizae varied among species, and (ii) the correspondence between above- and below-ground is imprecise at best at the community level. Keywords: mycorrhizal types, basidiocarps, sporocarps, fungal community, ecology of fungi, PCR, molecular ecology.
Gender variation and the evolution of dioecy in Thymelaea hirsuta (Thymelaeaceae)
Authors: El-Keblawy A. , Lovett-Doust J. , Lovett-Doust L.
Published: January 2008

Phenotypic gender in the evergreen shrub Thymelaea hirsuta was studied at regular intervals over 3–6 years in five natural populations in the western desert of Egypt. Quantitative estimates of gender were calculated for each plant, each year over the entire study period. Plants were also classified using a typological framework, allowing discrimination between plants that followed different flowering phenologies (e.g., dichogamy) but that may have had the same quantitative values of phenotypic gender. Two contrasting patterns of gender were revealed. Approximately one-third of all plants were stable in their gender expression (i.e., they produced the same floral pattern and quantitative gender on every occasion); the remainder had labile gender phenotypes, showing varying degrees and patterns of gender lability. The relative frequency of gender phenotypes differed significantly between sites. Stable unisexual forms were most prevalent at the depression sites, where the water table is closer to the soil surface. Patterns of gender variation in T. hirsuta can be interpreted in terms of a complex evolutionary pathway to dioecy, represented by several intermediate stages, including dichogamous, monoecious, and subdioecious individuals. Alternatively, there may be no directionality to the array; gender phenotypes may reflect localized selection that confers differential fitness on the phenotypes, to the extent that such phenotypes may be heritable. Keywords: dioecy, evolution, Thymelaea hirsuta, labile sex expression, gender variation.
Variation in the ginsenoside content of American ginseng, Panax quinquefolius L., roots
Authors: Smith Ron G. , Caswell Dave , Carriere Aura , Zielke Barbara
Published: January 2008

The weights and ginsenoside levels of twenty 4-year-old American ginseng (Panax quinquefolius) roots harvested from a homogeneous-looking 1-m2 plot were determined. It was found that the dry weight of the roots ranged from 3.5 to 22.8 g, a factor of 6.5; whereas the ginsenoside levels of these roots ranged from 24.7 to 56.4 μmol/g, a factor of 2.3. Further, it was found that the larger plants also contained higher ginsenoside levels on a weight basis. This finding is based, in part, on the ginsenosides in P. quinquefolius being located in both the periderm and cortex and the xylem and pith portions of the root. As the environmental variation experienced by the plants analyzed in this study was minimized, a portion of the variation found in these traits is likely to be a result of genetic diversity within the crop. These findings indicate that a cultivar of P. quinquefolius could be developed that would yield plants that have both an average weight and ginsenoside level per gram of tissue substantially greater than that of the existing crop. Keywords: Panax quinquefolius, American ginseng, ginsenosides, genetic selection.
Cryptic species withinAmphicarpaea bracteata(Leguminosae): evidence from isozymes, morphology, and pathogen specificity
Authors: Parker Matthew A.
Published: January 2008

All North American plants of the genus Amphicarpaea are currently classified into a single variable species (Amphicarpaea bracteata). However, an isozyme analysis of 33 populations from a 1000-km region revealed the presence of two divergent lineages (I, II) that shared no alleles in common at 7 of 18 loci examined. These lineages coexisted on both a local and a regional scale with virtually no hybridization: among nearly 1000 plants analyzed, only a single hybrid individual was found that had alleles from both lineages. A multivariate analysis of seven leaf traits showed that these lineages were morphologically distinct and that populations from the same lineage resembled each other regardless of geographic origin. The two lineages also showed divergent responses to isolates of the pathogen Synchytrium decipiens: pathogens sampled from either lineage failed to reproduce successfully on hosts of the other lineage. The correlated pattern of variation for all traits examined implies that these lineages constitute two separate biological species. Consistent (though less extreme) trait differences were also detected among two clusters of populations within lineage I, suggesting that this lineage may be further subdivided into two reproductively isolated sets of populations. Keywords: Amphicarpaea, electrophoresis, geographic variation, hybridization, Leguminosae.
Ageing and Human Muscle: Observations From Sweden
Authors: Lexell Jan
Published: January 2008

The purposes of this review are to summarize studies of cross-sections of autopsied whole muscles from previously physically healthy males and to focus on the cause of the ageing atrophy. The ageing atrophy begins around 25 years of age and thereafter accelerates. This is caused mainly by a loss of muscle fibres, and to a lesser extent by a reduction in fibre size, mostly of the proportion of the fibre area in the muscle cross-section occupied by type 2 (fast-twitch) fibres. In muscle from old subjects, there is a significant increase in the number of enclosed fibres, indicating an increased incidence of fibre type grouping, a loss of motor neurons in the spinal cord, and a reduction in the number of functioning motor units. These findings strongly suggest a combination of a progressive denervation process and an altered physical activity level as the two major mechanisms underlying the effects of normal ageing on human muscle. These changes have obvious implications for old individuals and their participation in physical activity and in sports, which must be accommodated in rehabilitation regimes or in training programmes. Key words: ageing, microscopy, muscles, physiological adaptation
Effects of Recovery Duration and Blood Lactate Level on Power Output During Cycling
Authors: Ainsworth Barbara E. , Serfass Robert C. , Leon Arthur S.
Published: January 2008

This study identifies the quickest recovery between consecutive anaerobic tests to maintain power output (PO) on the repeated test. Sixteen male cyclists finished three sessions of max rpm initial and repeated 45-s cycling tests at 53.9 N. Tests were separated by 6, 9, or 12 min of recovery cycling (80 rpm, 9.8 N). Results showed no significant differences in PO between initial tests (M = 578.5 ± 50 watts). PO was significantly less on the 6-min repeated test (M = 551.2 ± 51) compared to the 9- (M = 575.1 ± 53) and 12-min tests (M = 581.7 ± 49.9) (p > 0.05). Net blood lactate [HLa] (repeated test-recovery) was significantly related to net PO (repeated test-initial test) on the 9- (r = 0.60, p < 0.05) and 12-min (r = 0.64, p < 0.001) trials, but not on the 6-min trial (r = 0.35, p = 0.19). In summary, at least 9 min of recovery cycling maintains PO on a repeated 45-s cycling test. Elevated [HLa] at the onset of high-intensity sprint exercise is moderately associated with PO on repeated cycle ergometer tests. Key words: anaerobic exercise, cycling, power output, blood lactate, exercise recovery
The Effects of Active and Passive Recovery on Short-Term, High Intensity Power Output
Authors: Signorile Joseph F. , Tremblay Lisa M. , Ingalls Christopher
Published: January 2008

The advantage of active over passive recovery from long and intermediate duration exercise is well documented. Success has been attributed to metabolite washout and/or lactate (La) utilization by the active musculature. This study was designed to determine whether active recovery was superior to passive rest during short duration, high intensity performance. On 4 separate days, six athletes performed a set of eight 6-s power tests separated by 30-s recovery intervals under two recovery conditions. Recovery conditions involved either sitting passively on the bike (P) or actively pedaling (A) at 60 rpm using 1 kg resistance. A MANOVA on peak power (PP), fatigue rate (F), and total work (TW) showed a significant difference due to recovery condition, F(3, 169); p <.0001. Separate ANOVAs revealed that PP (A = 1192.85 watts, P = 1134.57 watts; p <.0001) and TW (A = 6.59 kJ, P = 6.23 kJ; p <.0001) differed significantly between conditions. No difference was found for F (A = 80.12 watts∙sec−1, P = 79.80 watts∙sec−1). Results indicate that active recovery provides superior performance to passive rest in repeated short-term, high intensity power activities. Key words: recovery, cycle ergometry, anaerobic power
The Relationship Between Cognitive Characteristics and Decision Making
Authors: Tenenbaum Gershon , Yuval Raya , Elbaz Gabi , Bar-Eli Michael , Weinberg Robert
Published: January 2008

Team handball players (N = 118) underwent a number of cognitive tests to examine how much of their decision making (DM) ability, as measured through responses to game slides projected to them for 2 seconds under low and high exertion levels (i.e., walking and running), was accounted for by cognitive components. A stepwise multiple linear regression indicated that experience was the most pronounced predictor of DM capacity in both exertion conditions. In the walking condition, concentrational consistency, avoidance of concentrational mistakes, and short-term memory, together with experience, produced a multiple R of 0.48 with decision making. In the running condition, choice reaction time (CRT), intelligence, and short-term memory, together with experience, correlated 0.46 with DM. These differences in cognitive abilities, as predictors of DM under walking and running conditions, are discussed in terms of information processing models and other cognitive processes. Key words: cognition, decision making, information processing
Fitness and Lifestyle Parameters Fail to Predict Back Injuries in Nurses
Authors: Ready A. Elizabeth , Boreskie Suzanne L. , Law Susan A. , Russell Robert
Published: January 2008

Performance on fitness and back related isometric strength tests, as well as the response to a lifestyle questionnaire, were related to the subsequent occurrence of back injuires in 119 nurses. In all, 22% of subjects sustained injuries during the 18-month study. Injured nurses were more likely to be from high-risk wards and to have received worker's compensation pay for past back injuries. Fitness and lifestyle characteristics did not differ significantly between injured and not-injured groups. Using backward stepwise logistic regression, a model was developed that accounted for 41% of the variability between groups and predicted 67% of those injured. Prior compensation pay, smoking status, and job satisfaction were the most useful discriminators. It was concluded, however, that the fitness and lifestyle parameters measured did not effectively predict back injury in nurses. Key words: fitness assessment, isometric strength, job satisfaction, job selection criteria, smoking status
Effects of Jet Lag on Factors Related to Sport Performance
Authors: Hill David W. , Hill Corinne M. , Fields Kelly L. , Smith Jimmy C.
Published: January 2008

Three studies were performed to evaluate the effects of jet lag on factors associated with sport performance. In Study 1, members of the USA Women's Soccer Team traveled to Taiwan; in Study 2, North American students and faculty traveled to Western Europe; and in Study 3, European students traveled to North America. After travel, there was disruption of mood state and a reduction in dynamic strength; peak 5-s power and 30-s work capacity were reduced for 2 days (5-s power: 9.8 vs. 9.0 vs. 9.0 W∙kg−1; 30-s work capacity: 213 vs. 199 vs. 201 J∙kg−1). In these studies, mood state, anaerobic power and capacity, and dynamic strength were affected by rapid transmeridianal travel, and even highly trained athletes suffered from jet lag. However, effects of travel on the variables tested were essentially eliminated after 3 or 4 days. Key words: circadian rhythm, anaerobic power, anaerobic capacity, mood, travel
Heart Rate/Stroke Volume Relationship During Upright Exercise in Long-Term Diabetics
Authors: Haennel R. G. , Teo K. K. , Suthijumroon A. , Senaratne M. P. J. , Hetherington M. , Ryan E. , Kappagoda C. T.
Published: January 2008

The changes in stroke volume (SV) during upright exercise were studied in 20 insulin-dependent diabetics (IDDM) and 20 age- and sex-matched controls. None of the diabetics had any cardiovascular symptoms. In addition, tests of autonomic function were conducted in the diabetics, assessing changes in heart rate (HR) during deep breathing and the Valsalva maneuver. During exercise the SV in the controls gradually increased and then remained essentially unchanged until maximum HR was achieved. Seven of the diabetics failed to sustain an initial increase in SV (fall > 15%), eight showed a "delayed" increase in SV, and the remaining five demonstrated an increasing SV over the range from rest to peak exercise. Abnormal autonomic function results were found during deep breathing (four diabetics) and the Valsalva maneuver (four diabetics). Findings indicate that cardiac function could be abnormal in IDDM without evidence of autonomic dysfunction. This abnormality could be due to a specific cardiomyopathy. Key words: diabetes mellitus, cardiac function, upright exercise, autonomic neuropathy, cardiomyopathy
Réponses physiologiques maximales lors d'un effort chez des sujets quadriplégiques
Authors: Simard Clermont , Noreau Luc , Paré Gilles , Pomerleau Pierre
Published: January 2008

Devices used for the assessment of physical working capacity in quadriplegics may be determinant in terms of efficiency during maximal exercise testing. The aim of this study was to compare the physiological responses of a group of quadriplegics during graded exercise tests on arm cranking ergometer (ACE) and wheelchair ergometer (WE). Fifty subjects, age 34.1 (± 9.5) years, participated in the study. Measurements comprised heart rate, ventilation, oxygen consumption, and power output. Unlike other studies suggesting a higher physical working capacity on ACE compared with WE, no significant differences were observed in physiological measurements between the two ergometers. However, power output on ACE was 65% higher than that of WE (p ≤ 0.001). These results suggest that power output of quadriplegics on ACE is higher due to differences in mechanical patterns required to induce movements of propelling (arm cranking vs. rolling movements). The need to link the assessment results to the type of locomotion used by the spinal cord injured persons may suggest the use of WE for testing and training in such individuals. Key words: quadriplegic, spinal cord injury, arm cranking and wheelchair ergometers, exercise testing, mechanical efficiency, physically disabled
Muscle Ultrastructure After Strength Training With Placebo or Anabolic Steroid
Authors: Kuipers H. , Binkhorst F. M. Peeze , Hartgens F. , Keizer H. A. , Wijnen J. A. G.
Published: January 2008

The influence of strength training on muscle fiber area, capillary ultrastructure, and capillary supply was studied in experienced male bodybuilders taking either anabolic steroids or a placebo. During 8 weeks, 13 subjects received a weekly injection of either placebo or nandrolone decanoate (starting dose 200 mg, followed by 100 mg weekly), in a double-blind, counterbalanced design. Before and after 8 weeks a needle biopsy was taken from the vastus lateralis muscle for studying morphometric characteristics of fibers and ultrastructure and morphometric characteristics of capillaries. The fiber cross-sectional area increased significantly only after steroid treatment. Capillary ultrastructure and capillary supply were not changed after the training period. In none of the measured parameters was any difference found between placebo and steroid treatment. Key words: fiber area, capillary supply, bodybuilders, nandrolone decanoate
The Calibration of a Sit-ups Task Using the Rasch Poisson Counts Model
Authors: Zhu Weimo , Safrit Margaret J.
Published: January 2008

The purpose of this study was to calibrate a nationally used sit-ups test using the Rasch Poisson Counts model and evaluate the model-data fit. The total number of subjects was 8,723, consisting of 4,486 girls and 4,237 boys, ages 10 to 18. The estimated difficulty of the sit-ups task was −2.80, which was appropriate for a majority of examinees whose ability levels ranged from.09 to 1.39. After the calibration, boys and girls as well as different age groups were compared under the same metric. Graphs of the model-data fit demonstrated that the model-data fit at a low ability level was not as good as the fit at a high ability, which could be caused by violation of assumptions of the model that examinees have the same performance speed throughout the test and that the speed at a given time is independent of the number of sit-ups completed so far. Key words: item response theory, modeling of motor performance, fitness testing
Torque/Velocity Properties of Human Knee Muscles: Peak and Angle-Specific Estimates
Authors: Caldwell Graham E. , Adams III William B. , Whetstone Melinda R.
Published: January 2008

Angle-specific (AS) torque/velocity data have been used to avoid angle related variation in peak torque capacity. However, series elastic structures cause the contractile velocity of active force-producing tissue to differ from external joint velocity except at peak torque. Alternatively, angle related variation may be removed by normalizing peak torque to the isometric maximum at that angular position. The AS, peak (P), and normalized peak (NP) methods were compared in isovelocity knee flexion and extension at velocities between 50 and 250° s−1 for 8 male subjects. The P and NP methods gave more similar torque/velocity relations than the AS method. Further, very little variation in peak torque was attributed to differences in joint angle. Both the P and AS methods illustrate that relative quadriceps/hamstrings torque capability (flexor/extensor ratio) increases slightly with velocity. It is proposed that antagonist muscle torque capabilities should be compared at different angular positions to assess muscular imbalance. Key words: muscle properties, muscle imbalance, force/velocity, isovelocity, antagonists
Metabolic Adaptations to Endurance Training in Older Individuals
Authors: Marsh Gregory D. , Paterson Donald H. , Thompson R. Terry , Cheung Po Kee , Arnold J. Malcolm O. , MacDermid Joy
Published: January 2008

The purpose of this study was to describe the effects of moderate intensity exercise training on the muscle energy utilization, blood flow, and exercise performance of four sedentary older individuals (58 ± 4 yrs). Subjects trained the dominant forearm each day for 12 weeks. The nondominant arm was not trained and served as a within-subject control. 31P nuclear magnetic resonance spectroscopy (31P NMRS) was used to identify the power output in watts (W) at the onset, or threshold, of intracellular acidosis (IT) in the exercising muscle during progressive exercise tests to fatigue. After 6 weeks of training, power output at the IT increased by 14% (p < 0.05) in the dominant arm; however, an additional 6 weeks of the same exercise program failed to produce a further increase in IT power. IT power of the nondominant forearm was not changed. In the dominant forearm, endurance time for a submaximal wrist flexion test was increased 34% and 58% at 6 and 12 weeks, respectively. Maximal voluntary strength was not affected by training, nor was resting or exercising blood flow. The training program delayed the onset of intracellular acidosis during progressive exercise and increased the capacity for submaximal work. These effects did not appear to depend on an increase in muscle blood flow. Key words: 31P nuclear magnetic resonance spectroscopy, muscle metabolism, exercise training
Effect of Cardiac-Locomotor Coupling on the Metabolic Efficiency of Pedalling
Authors: Donville Jane E. , Doherty Timothy J. , Kirby R. Lee , Gupta Sanjay K. , Eastwood Brian J. , MacLeod Donald A.
Published: January 2008

Coupling between cardiac and locomotor rhythms (CLC) has been reported while subjects exercise at cadences that are natural to them. The hypothesis that oxygen consumption [Formula: see text] would be lower when subjects pedalled at the rate producing 1:1 coupling of heart and pedalling rates than when they pedalled at noncoupled rates was tested with 12 men on a cycle ergometer. At a moderate power output based on their [Formula: see text] max, subjects pedalled at six different pedalling rates while [Formula: see text] and heart rate were measured. The pedalling rates were the preferred frequency, frequencies 15 and 30% above and below the preferred frequency, and the 1:1 coupled frequency. In 8 of the 12 subjects it was possible to fit their data with significant regression equations relating [Formula: see text] to pedalling rate, but in no subject was the 1:1 coupled state energetically beneficial, suggesting that any functional significance of CLC is unrelated to metabolic efficiency. Key words: exercise, cycling, integration, biological clock
Mitochondrial Biogenesis in Striated Muscle
Authors: Hood David A. , Balaban Atila , Connor Michael K. , Craig Elaine E. , Nishio Mary L. , Rezvani Mojgan , Takahashi Mark
Published: January 2008

Mitochondrial biogenesis (synthesis) has been observed to occur in skeletal muscle in response to chronic use. It also occurs in cardiac muscle during growth and hypertrophy, and it may be impaired during the aging process. This review summarizes the literature on the processes of mitochondrial biogenesis at the biochemical and molecular levels, with particular reference to striated muscles. Mitochondrial biogenesis involves the expression of nuclear and mitochondrial genes and the coordination of these two genomes, the synthesis of proteins and phospholipids and their import into the organelle, and the incorporation of these lipids and proteins into their appropriate locations within the matrix, inner or outer membranes. The emphasis is on the regulation of these events, with information derived in part from other cellular systems. Although descriptions of mitochondrial content changes in heart and skeletal muscle during altered physiological states are plentiful, much work is needed at the molecular level to investigate the regulatory processes involved. A knowledge of biochemical and molecular biology techniques is essential for continued progress in the field. This is a promising area, and potential new avenues for future research are suggested. Key words: heart, skeletal muscle, gene expression, heme metabolism, protein import
Effect of Training on the Blood Pressure Response to Weight Lifting
Authors: Sale Digby G. , Moroz Dianne E. , McKelvie Robert S. , MacDougall J. Duncan , McCartney Neil
Published: January 2008

Six young men weight trained 3 days∙week−1 for 19 weeks, on each day doing 3 warm-up sets of 20 repetitions followed by 1 set each at 15-20, 10-15, and 7-10 RM (Day 1), 3 sets at 15-20 RM (Day 2), and 1 set at 15-20 and 2 sets at 10-15 RM (Day 3) of a seated bilateral leg press exercise. Training increased (P < 0.05) the maximal single leg press lift (1-RM, 26%) and knee extensor cross-sectional area (12%). Arterial (brachial artery catheter) and esophageal (probe) pressure responses were measured before and after training as subjects did sets of as many repetitions as possible up to 20 reps with 50, 70, 80, 85, and 87.5% 1-RM. After training, peak values of systolic pressure attained during a set (M pre/post, mm Hg) were significantly (P < 0.05) increased at 85% (325/360,10.8%) 1-RM. Peak diastolic pressure increased significantly at 50 (136/151, 11.0%), 70 (185/200, 8.1%), and 80% (215/234, 8.8%). Peak esophageal pressure increased significantly at 80% (71/91, 28.2%) 1-RM. For a given absolute weight lifted, all responses were markedly reduced after training. It is concluded that weight training can (a) increase the peak arterial and esophageal pressure responses attained during maximal weight lifting exercise, and (b) reduce the arterial and esophageal pressure responses to lifting the same absolute weight. Key words: weight training, systolic pressure, diastolic pressure, esophageal pressure, Valsalva maneuver
Development of Physical Fitness Standards for Canadian Armed Forces Older Personnel
Authors: Stevenson Joan M. , Deakin Janice M. , Andrew George M. , Thomson John M. , Bryant J. Timothy , Smith J. Terry
Published: January 2008

The purpose of the study was to develop a minimum physical fitness standard for Canadian Forces personnel, 35 years and older, based on common criteria for physically demanding tasks. A random sample of 100 men and 76 women performed the Exercise Prescription (EXPRES) test and five physically demanding tasks that simulate common military tasks, while restricted, for safety reasons, to 90% maximal predicted heart rate. Results indicated poor predictive power, as variances ranged from 5 to 55% between EXPRES fitness scores and task performance. With approval from an expert panel, the 75th percentile score for each task was selected as the cutting criterion. The passing-group data were converted to Z-scores in order to determine the 5th percentile from each EXPRES item: these scores became the EXPRES fitness standard. The minimum fitness standard had a greater impact on women than on men but was representative of the passing groups for both sexes. Key words: occupational selection standards, employee selection, personnel selection, screening, job related performance tests
Physiological and Psychological Responses to Eccentric Exercise
Authors: Thomas Tom R. , Londeree Ben R. , Lawson Deborah A. , Ziogas George , Cox Richard H.
Published: January 2008

In order to compare the physiological and psychological responses to various levels of eccentric exercise, 7 active men (25 ± 5 yrs) exercised for 60 min on separate days at 60% of apparatus specific [Formula: see text] max using downhill jogging (−5% 60DH), level jogging (60J), and cycling (60C). Virtually all of the responses to 60DH fell between 60J and 60C. Heart rate, O2 pulse, and respiratory exchange ratio were significantly different among modes, with the responses during 60DH falling between those during 60J and 60C. Fat energy expenditure during the 60-min exercise bout was significantly higher during 60J, followed by 60DH and then 60C. Ratings of perceived exertion followed the order of 60C > 60DH > 60J. Vigor and fatigue scores on the Profile of Mood States also followed a hierarchy that paralleled the physiological responses. These results suggest that downhill jogging elicits physiological and psychological responses that are between those elicited by level jogging and cycling. Key words: energy expenditure, fat energy expenditure, ratings of perceived exertion, eccentric contractions
Comparison of Whole and Split Weight Training Routines in Young Women
Authors: Calder Aaron W. , Chilibeck Phil D. , Webber Colin E. , Sale Digby G.
Published: January 2008

Thirty young women comprised three groups (n = 10 in each): whole routine (W) training, split routine training (S), and control. The W group did four upper (five sets, 6-10 RM) and three lower body (five sets, 10-12 RM) weight training exercises together in single sessions twice a week for 20 weeks. The S group did the upper body exercises 2 days a week and the lower body exercises on 2 other days of the week. The single maximal weight lift (1-RM) increased (p < 0.05) (W/S) 54/69%, 33/32%, and 21/22% in arm curl, bench press, and leg press exercises, as did arm (10/9%), and trunk (3.4/2.7%) lean tissue mass, as measured by dual energy x-ray absorptiometry. Leg lean mass increased significantly only in W (4.9% vs. 1.7% in S). Whole-body lean tissue mass increased (4.1/2.6%), and whole body % fat (−1.1/−1.3%) decreased with training. It is concluded that in healthy young women, whole and split weight training routines produce similar results over the first 5 months of training. Key words: resistance training, strength, muscle mass, body composition
Principal Components of Fitness: Relationship to Physical Activity and Lifestyle
Authors: Shephard Roy J. , Bouchard Claude
Published: January 2008

Interrelationships between metabolic and cardiorespiratory health were examined in 350 healthy adults. Four principal components accounted for 66.7% of the variance in 172 males (M) and for 62.4% in 178 females (F). Factor 1, "obesity," related to body mass index, abdominal circumference, total skinfold thickness, and (M only) abdominal/hip circumference ratio. Factor 2, "cardiovascular fitness," had loadings from resting heart rate and PWC150/kg. Factors 3 and 4 were related to total cholesterol and HDL-cholesterol, respectively (plus blood pressures, particularly in F). Factor 1 was linked to caffeine consumption and to exercise frequency (F) or perceived intensity (M). Factor 2 was linked to perceptions of activity relative to others (M and F) and to the intensity of activity (M only). Factors 3 and 4 were associated with perceived fitness and physical activity relative to others. Because perceptions of physical activity and fitness lack consistency, it is suggested that health be judged more directly from simple measures of health related fitness that require little subject cooperation. Key words: caffeine consumption, cardiorespiratory fitness, gender differences, health related fitness, metabolic fitness, perceived activity
Peripheral and Central Chemoreceptor Control of Ventilation During Exercise in Humans
Authors: Ward Susan A.
Published: January 2008

The stability of arterial blood gas tensions and pH during steady-state moderate exercise has suggested an important humoral element of ventilatory control in humans. However, the involvement of central and peripheral chemoreflexes in this humoral control remains controversial. This reflects, in large part, technical and interpretational limitations inherent in currently used estimators of chemoreflexes "sensitivity." Evidence suggests that the central chemoreceptors (a) contribute little during moderate exercise, given the relative stability of cerebrospinal pH, (b) constrain the hyperpnea of high-intensity exercise, consequent to the respiratory compensation for the metabolic acidemia, and (c) may play a role in the respiratory compensation during chronic metabolic acidemia. In contrast, the peripheral chemoreceptors appear to (a) exert considerable influence on ventilatory kinetics in moderate exercise, but are less important in the steady state, and (b) induce much of the respiratory compensation of high-intensity exercise. Key words: medullary chemoreceptors, carotid chemoreceptors, hyperoxia, ventilatory dynamics, metabolic acidemia
Endocrine Responses to Overreaching Before and After 1 Year of Weightlifting
Authors: Fry Andrew C. , Kraemer William J. , Gordon Scott E. , Stone Michael H. , Warren Beverly J. , Fleck Steven J. , Kearney Jay T.
Published: January 2008

Nine elite male junior weightlifters (mean age 17.6 ± 0.3 yrs) performed weightlifting tests before (Test 1) and after (Test 2) 1 week of increased training volume (overreaching) and repeated the protocol after 1 year of their training program. Strength increased by Year 2 (p < 0.05) but did not change during either week of increased training volume. The 1-week overreaching stimulus resulted in attenuated exercise-induced testosterone concentrations during Year 1, but augmented exercise-induced testosterone concentrations during Year 2. Testosterone concentrations at 7 a.m. decreased for only Year 1. For both years, the 1-week overreaching stimulus increased Cortisol at 7 a.m., indicative of the increased training volumes. Testosterone/Cortisol was not affected by increased training volume for either year. One year of chronic weightlifting and prior exposure to the overreaching stimulus appears to decrease the detrimental effects of stressful training on the endocrine system. Key words: testosterone, Cortisol, weightlifting, overtraining
Hematological, Electrolyte, and Biochemical Alterations After a 100-km Run
Authors: Rama Ramón , Ibáñez Jordi , Riera Miguel , Prats Maria T. , Pagés Teresa , Palacios Luis
Published: January 2008

Seven well-trained male long-distance runners were studied during a 100-km road race. Hematologic parameters, plasma electrolytes, glucose, lactate, urea, and creatinine content in plasma and the activity of the enzymes γ-glutamyltransferase and creatine kinase were determined before and after the race. A slight increase in hematocrit was found after the race, although the red blood cell count and hemoglobin concentration remained unchanged. Further, a significant rise in the number of white blood cells, lymphocytes, and neutrophils was found after the race. Postrun concentrations of plasma sodium and potassium increased significantly from 142 ± 7 to 161 ± 7 mmol∙L−1, and from 4.22 ± 0.37 to 5.15 ± 0.46 mmol∙L−1 (p < 0.05), respectively. Plasma concentrations of lactate (1.29 ± 0.31 vs. 3.57 ± 1.22 mmol∙L−1), urea (6.09 ± 1.0 vs. 8.35 ± 1.35 mmol∙L−1), creatinine (73.4 ± 3.5 vs. 117.6 ± 19.4 μmol∙L−1), plasma creatine kinase (91.1 ± 25.1 vs. 2843 ± 2341 IU∙L−1), and γ-glutamyltransferase (20.28 ± 1.88 vs. 24.14 ± 4.09 IU∙L−1) increased significantly (p < 0.05) after the run. It was concluded that during ultralong-distance races, acute renal dysfunction and muscle damage could contribute to the observed hypernatremia and hyperkalemia. Key words: ultralong-distance races, hematological parameters, plasma electrolytes, plasma creatinine, creatine kinase
Entrained Breathing and Oxygen Consumption During Treadmill Walking
Authors: Alphen Jane van , Duffin James
Published: January 2008

Entrainment of the breathing rhythm to that of the rhythm of limb movement during exercise has been shown to decrease oxygen consumption for cycling at a moderate workload. This study examined the effect of entrainment on oxygen consumption during treadmill walking at two workloads. For each workload, 8 subjects performed two exercise protocols consisting of walking on a treadmill for 8 min. For the first protocol they received no instructions, but for the second protocol they were instructed to coordinate one breath per auditory cue which was provided during the last 4 min of exercise. The auditory cue was transmitted as a click via headphones. It was derived from a foot switch and was designed to synchronize breathing to the walking pace at a respiratory frequency close to that observed in the first protocol. Entrainment and oxygen consumption were compared between the protocols for the last 4-min segments for each workload. These comparisons showed that the presence of the auditory cue significantly increased entrainment from 29 to 74%, but oxygen consumption was not significantly changed. Key words: breathing pattern, entrainment, exercise, locomotor-respiratory coupling, ventilation
Twitch Analysis as an Approach to Motor Unit Activation During Electrical Stimulation
Authors: Heyters Marc , Carpentier Alain , Duchateau Jacques , Hainaut Karl
Published: January 2008

The mechanical twitch in response to increasing electrical stimulus intensity, delivered both over the motor point and motor nerve, was recorded in the first dorsal interosseous (FDI) and the adductor pollicis (AP), and only over the motor point in the soleus (Sol), lateral (LG), and medial (MG) gastrocnemius muscles of human subjects. The relationship between intensity of electrical stimulation (ES) and twitch torque showed a positive linear regression in all muscles. In the FDI and AP the relationship was not significantly different when ES was applied at the motor point or over the motor nerve. At small intensities of activation, ES induced larger twitch torques in the MG and LG, which contain a roughly equal proportion of slow and fast motor units (MUs) compared to the Sol, which is composed mainly of slow type fibres. Moreover, the relationship between ES intensity and twitch time-to-peak is best fitted in all muscles by a power curve that shows a greater twitch time-to-peak range in its initial part for muscles containing a larger proportion of fast MUs (LG, MG) than for muscles mainly composed of slow MUs (Sol). In conclusion, these results induced by ES at the motor point and/or over the motor nerve confirm the concept of a reversed sequence of MU activation, as compared to voluntary contractions, and document this viewpoint in muscles of different function and composition. The reversed sequence of MU activation is more clearly evident during motor point ES. Key words: muscle contraction, mechanical twitch, motor point, nerve
L(+)-Lactate Binding to a Protein in Rat Skeletal Muscle Plasma Membranes
Authors: McCullagh Karl J. A. , Bonen Arend
Published: January 2008

Biochemical studies were conducted to determine the location of a putative lactate transport protein in rat skeletal muscle plasma membranes (PM). PM (50-100 μg protein) were incubated with [U-14C] L(+)-lactate, in the presence or absence of unlabeled monocarboxylates or potential inhibitors, after which proteins were separated by SDS-PAGE. Gel slices (2 mm) were cut and analyzed for14C. [U-14C] L(+)-lactate was bound to plasma membranes in the 30 to 40 kDa molecular mass range. Binding of [U-14C] L(+)-lactate was inhibited by N-ethylmaleimide, unlabeled L-lactate and pyruvate, and in a dose dependent manner by α-cyano-4-hydroxycinnamate (r = 0.995), but not by cytochalasin-B. The inhibition of [U-14C] L(+)-lactate binding was similar to the inhibition of lactate transport. Therefore the transport of L(+)-lactate across skeletal muscle plasma membranes involves a polypeptide of 30 to 40 kDa. Key words: transport, affinity labeling
A Study to Validate the Modified Canadian Aerobic Fitness Test
Authors: Weller Iris M. R. , Thomas Scott G. , Gledhill Norm , Paterson Don , Quinney Art
Published: January 2008

This study evaluated the predictive ability of the modified Canadian Aerobic Fitness Test (mCAFT) on an independent sample of subjects and compared it to the original Canadian Aerobic Fitness Test (CAFT). Male and female subjects (n = 154), 15-69 yrs of age, performed the mCAFT and a maximal treadmill test. [Formula: see text]max scores predicted from the mCAFT equation did not differ significantly from those measured during the treadmill test, whether the sample was analysed overall or categorized by sex, whereas the CAFT (Jetté) equation resulted in [Formula: see text]max scores that were significantly lower than either the measured values or those predicted using the mCAFT. The strength of the linear relationship between predicted and measured [Formula: see text]max scores is the same for both the mCAFT (r = 0.88) and CAFT (r = 0.89). However, the mCAFT results in a lower mean square error (37.0 for mCAFT vs. 63.3 for CAFT) and thus is an improvement over the CAFT prediction. Key words: exercise test, direct oxygen consumption, predictive value of tests, physical fitness, epidemiologic methods
Benefits of Exercise for Type II Diabetics: Convergence of Epidemiologic, Physiologic, and Molecular Evidence
Authors: Bonen Arend
Published: January 2008

In Canada diabetes affects ~5% of the population. The economic costs of diabetes and its attendant complications are significant, requiring approximately $1 billion a year from the health care system. Clearly the prevention and alleviation of diabetes is highly desirable. In the past few years there has been a remarkable convergence of physiologic, biochemical, molecular, and epidemiologic data, all of which indicate very strongly that exercise may be used as a therapeutic tool to prevent or alleviate non-insulin-dependent diabetes mellitus (NIDDM), or Type II diabetes. The evidence for this has been reviewed. Recently the significant therapeutic role of exercise for Type II diabetics has been endorsed by the medical community. However, there is virtually no education of exercise professionals in the area of diabetes and the benefits of lifestyle changes in treating Type II diabetics. This deficiency should be remedied. For the research community, the challenge now is to translate the physiologic, biochemical, and epidemiologic knowledge into optimally effective prescriptive exercise programs for Type II diabetic men and women. Key words: glucose, insulin, muscle, review
Origins of [H+] Changes in Exercising Skeletal Muscle
Authors: Lindinger Michael I.
Published: January 2008

This brief review describes the main physicochemical factors that contribute to increases in intracellular hydrogen ion concentration ([H+]i) in mammalian skeletal muscle during high intensity exercise. High intensity exercise results in changes in the three main independent physicochemical variables: PCO2, the strong ion difference ([SID]), and total concentration of weak acids and bases ([Atot]), within the intracellular fluid compartment of contracting muscle that result in increased [H+]i. The decrease in [SID] contributes 62% to the increase in [H+]i, due to decreased [K+]i and increased [lactate]i; the decrease in phosphocreatine ([PCr2−]i) exerts an alkalinizing effect. The increase in [Atot], resulting primarily from increases in inorganic phosphate and creatine as a result of PCr2− breakdown, contributes 19% to the increase in [H+]i. An increase in the apparent proton dissociation constant (KA) for [Atot] contributes 7% to the increase in [H+]i. PCO2 is a relatively poor effector of changes in [H+]i, such that a 50-mmHg increase in PCO2 contributes only 12% to the increase in [H+]i during high intensity exercise. Key words: acid-base balance, strong ion difference, phosphocreatine, potassium, carbon dioxide, metabolism
Contribution of Acid-Base Changes to Control of Breathing During Exercise
Authors: Forster Hubert V. , Pan Lawrence G.
Published: January 2008

The mechanisms mediating the exercise hyperpnea remain controversial; there is no unequivocal evidence that any of numerous proposed mechanisms mediates the hyperpnea. However, a great deal has been learned including the potential role of changes in PCO2, [H+], strong ion differences (SID), weak acids, or any other acid-base component. The contribution of acid-base changes to the hyperpnea during exercise is likely through known or postulated chemoreceptors. Two of these, pulmonary and intracranial chemoreceptors, do not appear critical for the ventilatory adjustments to meet the metabolic demands of exercise. A third, the carotid chemoreceptors, appear to fine-tune alveolar ventilation during exercise to minimize disruptions in arterial blood gases. The role of the fourth chemoreceptors, those within skeletal muscles, is least clear. However, there is evidence that they do contribute to the hyperpnea, and it is quite clear that a muscle chemoreflex contributes to the exercise muscle pressor reflex; thus the contribution of these chemoreceptors to the exercise hyperpnea requires additional study. Key words: ventilation, hydrogen ion, PaCO2, PO2