Canadian journal of applied sport sciences. Journal canadien des sciences appliquees au sport最新文献

The only major methodological problem associated with the enzymatic determination of blood lactate levels is the stability of the metabolite in the perchloric acid supernatant. The data from this study show that freezing the protein-free supernatant provides a viable method for the prolonged, stable storage of blood lactate.

The purpose of this study was to analyze the relationship between the goal and systems models of organizational effectiveness in Canadian National Sport Governing Bodies. The major issue addressed was whether elite amateur sport organizations which are more successful at acquiring scarce financial resources, are also more successful at achieving goals of performance excellence. World rankings, changes in world rankings and an effectiveness ranking, which accounts for the number of competing countries, were used to measure the degree to which the organizations are achieving their goals of performance excellence. The 1982 total operating budget of each NSGB and the increase in financial support received from Fitness and Amateur Sport from 1970 to 1982 were used to measure the ability of the NSGBs to acquire scarce financial resources under the systems model of effectiveness. The results revealed that one of the goal model indicators, the effectiveness ranking, was positively and significantly correlated with one of the system model indicators, the total operating budget. This suggests that the ability to acquire scarce financial resources is related to the ability of an NSGB to achieve its goal of performance excellence. This also suggests that the goal and systems models may be complementary methods of measuring the concept of organizational effectiveness even though they are most often viewed as being alternative approaches in the literature.

This study examined motives for participating in and discontinuing sport for 106 competitive, recreational, and former youth gymnasts. Similar to previous studies on participation motives in children's sport, gymnasts cited multiple reasons for their attraction to sport with the most important being competence, fitness, and challenge for the competitive gymnasts; competence, fitness, fun and situational for the recreational gymnasts; and competence, action, challenge and fun for the former gymnasts. A factor analysis was conducted and revealed seven categories of motivational factors, similar to those found by Gill et al. (1983). No support was found for a relationship between motives for gymnastic participation and reasons for attrition. The most important reasons for leaving gymnastics were having other things to do, injuries, not liking the pressure, not having enough fun, and too time consuming.

Nuclear magnetic resonance imaging (MRI) is a technique which gives body images in much the same way as X-ray tomography. Most images are produced from signals of mobile hydrogen atoms in the tissues. Since bone contains few such atoms the images do not show bone material but allow marrow to be observed. Recently the technique has been extended to include spectroscopy of atoms of 31P, 13C and several others important in cell and tissue metabolism. The technique which uses a radiofrequency surface coil placed over the tissue of interest, is called topical magnetic resonance spectroscopy (MRS). Magnetic resonance spectroscopy which measures phosphorus nuclei can be used to study phosphorus in muscle. The same instrument can be used to study hydrogen density distribution. It can monitor muscle metabolism during exercise and muscle energetics can thus be evaluated. MRS gives a more accurate picture of the in vivo proportions of high energy phosphates than conventional biochemical analysis, which requires muscle biopsy, it can be used to monitor living tissue in a non-destructive way.

Three, 15 minute recovery modes between two maximal effort, intermittent work bouts were tested using eight male hockey players (21.9 +/- 1.4 yrs.). The work bouts were comprised of six, 45 second skating trials, each interspersed with 90 seconds of rest. Performance scores were based on average distance skated/trial. Changes in lactate concentrations were determined from venous samples obtained at rest, prior to and following the recovery mode. Bench-stepping during recovery resulted in significantly lower lactates (6.1 +/- 2.2 mmol . 1-1) than for rest recovery (8.1 +/- 1.6 mmol . 1-1), while skating recovery was not significantly different from either bench-stepping or rest. Subsequent performance (WB2) was significantly lower than initial performance (WB1) for all treatments and it was unrelated to differing post-recovery lactate concentrations. It was concluded that bench-stepping enhanced lactate removal but subsequent performance was unaffected by any treatment.

Echocardiographic studies related to chronic exercise effects on cardiac dimensions were reviewed. Sources of error in M-mode echocardiography include its resolving power, changes in transmission velocity in a nonhomogeneous medium, subjective analysis of records, and assumptions to predict ventricular volume and mass from one-dimensional data. Existing studies document larger values for left ventricular internal diastolic dimension (LVIDd) in endurance athletes, and for septal and posterior wall thicknesses (ST, PWT) in endurance, strength-type and anaerobic-type athletes compared to nonathletes. Values for the athletes were lower than in cardiac disease states. Short-term conditioning studies generally reported unimpressive changes in ventricular dimensions. Existing literature also does not clearly support a relationship between training intensity and the degree of cardiac enlargement, or changes in the heart's trainability with age. Hereditary and/or familial factors appear to influence heart size to some degree and a correlation with anthropometric variables may exist. Further study concerning hereditary and long-term conditioning effects is recommended.

The purpose of the study was to examine the relationship between personality and ability in wrestling. A wrestling-specific version of the Jackson Personality Inventory (JPI-W) was constructed and compared to the parent JPI. Wrestlers were categorized as qualifiers (N = 46) or nonqualifiers (N = 52) on the basis of an ability classification scheme which involved the previous year's performance at specified tournaments. These two groups were then examined for differences on eight JPI scales (anxiety, energy level, interpersonal affect, organization, risk taking, self esteem, social participation, and tolerance), eight corresponding JPI-W scales, wrestling age category (senior, junior, and juvenile), and wrestling experience. The results indicated that in comparison to nonqualifiers, qualifiers had significantly greater wrestling experience and higher self esteem as measured by the JPI-W.

The self-organization of biological systems is, in part, described by dynamical order and cooperativity of system elements. Consideration of this, therefore, should form the infrastructure of future Exercise/Sport Biochemistry Research in Canada since a solely elemental focus, in its' interpretation, may not be meaningful if the synergy among system elements is not appreciated. This approach is illustrated through a description of the central role of Ca2+ metabolism in coordinating subcellular events associated with muscle contraction. The decline in force generating capabilities associated with extreme muscle use (e.g. endurance type exercise) is, in our view, due to an uncoupling of excitation-contraction coupling leading a Ca2+ imbalance. The observed dissolution of the myofibril ultrastructure and altered SR function reflect a loss of normal order and synergy amongst Ca2+ regulated and Ca2+ regulating processes which will lead to an upcoupling of oxidative phosphorylation. These apparently catastrophic events may, paradoxically, establish a new order in which energy utilizing systems attempt to keep pace with the abbreviated energy production system.

The purpose of this study was to determine whether or not trained athletes have the same capacity for supercompensation of muscle glycogen as untrained subjects. Muscle glycogen was measured in 4 highly trained cyclists and 4 untrained controls over a 6 day period of exercise and dietary manipulation. During the week prior to the investigation the trained group tapered their training load but maintained a high carbohydrate intake as they would in preparation for a major competition. Needle biopsies were taken from the vastus lateralis before and after exhaustive cycle ergometry at 73% VO2 max followed by several sprint intervals, after 3 days on a carbohydrate-restricted diet and after 2 and 3 days on a high carbohydrate diet. All food intake was quantified and plasma insulin and glucose were monitored daily. The mean initial glycogen concentration for the trained group was 115 mmol X kg-1 wet muscle weight and 92 mmol X kg-1 for the untrained group. Both groups showed similar post exercise depletion and recovery patterns when expressed as a % of their initial values. Following 3 days of high carbohydrate diet, the glycogen concentration for the trained cyclists reached 174 mmol X kg-1 or 152% of its initial value while the untrained-group reached 143 mmol X kg-1 or 155% of its initial value. It was concluded that a regimen of exhaustive exercise, followed by a period of carbohydrate restriction and a period of high carbohydrate intake, results in substantially higher muscle glycogen storage than can be achieved by a reduction in training in combination with high carbohydrate intake.(ABSTRACT TRUNCATED AT 250 WORDS)

Definition of the exercise model via a mechanistic approach is a goal which should be of high priority among sport researchers in the 1990's, in an attempt to further qualify previous phenomenological observations of exercising man. Prolonged argument on the "theory-versus-practice" issue is one which is counter-productive in the advancement of knowledge in our discipline, and must be addressed and resolved. With specific emphasis on the neuromuscular control of movement, current research literature suggests that the components limiting to human performance may reside in the muscle, motoneurone and in the supraspinal of movement. Mechanistically defining the limits in each component, related to patterns of movement during exercise, may soon herald a reclassification of exercise types and their limits, defined by the particular system involved. Similarly, new evidence on adaptations throughout the neuromuscular system calls for a systematic study of these adaptations, how they influence structure and function of cell and organ systems, and their effects on the performance of the voluntarily exercising human. A mechanistic approach to these problems, using "simple" experimental models to more precisely define cause-effect, are justifiable and necessary in our field on the basis of the potential applicability of such information in the fields of design of exercise programmes, and the evaluation of their effectiveness, for normal and special populations. The problems associated with increased academic specialization and the communication gap which might result, are not inevitable. An enhancement of the proliferation of this knowledge and its interpretation in practical terms will result through our own awareness of the necessity of doing this, and through sensitization of our students to this issue.