Showing papers in "Journal canadien des sciences du sport in 1988"

Inter-generation transmission of physical fitness in the Canadian population.

Abstract: Body weight, height, body mass index, skinfold measurements, waist-to-hip ratio (WHR), somatotype components, muscular endurance and strength, flexibility, resting heart rate and submaximal power output (PWC150/kg) were measured in 13,804 subjects during the 1981 Canada Fitness Survey. Familial correlations were computed to determine the contribution of transmissible (t2) and environmental (e2) factors in physical fitness by path analysis. Transmissibility estimates (t2) under 0.30 for weight, height, WHR and PWC150/kg, above 0.40 for mesomorphy, ectomorphy, push-up test and flexibility, and between 0.30 and 0.40 for the other measurements were obtained. These results suggest that e2 account for more than 50% of the variation and that the average total biological and cultural inheritance from parents to offspring in physical fitness of Canadians accounts for 30% to 40% of the phenotypic variation.

Breath-by-breath oxygen consumption during performance of the Wingate Test.

Abstract: The aerobic contribution to the Wingate Anaerobic Power Test (WAnT) was evaluated by measuring breath-by-breath oxygen consumption (VO2) in five male subjects. Assuming an optimal mechanical efficiency, net VO2 during the WAnT could account for about 18.5% of the work performed.

Advance cues and their use in predicting tennis passing shots.

Abstract: The present investigation represents an attempt to begin to delineate the specific advance cues that tennis players might employ as a basis for predicting the passing shots (i.e., forehand and backhand; down-the-line, cross-court, or lob) of their opponents and, as well, to evaluate the predictive accuracy of any such cues identified. In addition, an effort has been made to determine whether individuals judged to possess advanced tennis skills make more effective use of available telegraphic cues than do those players considered to possess only an intermediate level of overall tennis proficiency. The results obtained indicate that advance body-language cues do exist that accurately forecast passing-shot location, and this is particularly true for forehand shots. Some of the actual cues employed are reported. Generally, advanced players predicted passing-shot type more accurately than did their intermediate counterparts. In some instances, this difference in accuracy can be attributed to the fact that the intermediate players were unaware of what the telegraphic cues were (e.g., backhand shots) while, in other situations, the difference in prediction ability is primarily due to the intermediate players' more frequent failure to detect the presence of known telegraphic cues (i.e., forehand shots).

Frequency and predictability of sports injuries in intercollegiate athletes.

Abstract: This study analyzes injury frequency and predictability in 712 intercollegiate athletes in 24 different male and female sports over the 1984-85 season. The injury rate was 38% for males and 32% for females, with the males suffering more acute injuries. While the men's hockey team had the highest player injury rate, the football team had the greatest absolute number of injuries. Overall, the anatomic location with the highest injury rate was the knee, while sprains were the most common type of injury. Further elaboration of these results are provided in graphic form. By comparing injury occurrence to past history and preparticipation physical findings, this study assesses the predictability of injury. With one exception, no significant relationship was found. It would appear that the preseason exam may play a role in identification, rather than prediction of sports injuries. Language: en

The Effect of Exercise Duration on the Exercise and Post-Exercise Oxygen Consumption

Abstract: This study was designed to determine the effect of duration (30, 45, 60 min) of exercise at 70% VO2 max on oxygen consumption during the exercise and post-exercise periods and if the post-exercise oxygen consumption (EPOC) is related to elevated tympanic temperature. Two male and three female volunteer subjects cycled at 70% VO2 max for 30, 45 and 60 min. The EPOC increased 2.35 and 5.3 fold when exercise duration was increased from 30 to 45 min and from 30 to 60 min respectively. The time for VO2 to return to resting levels following exercise was 128 +/- 4.4 min, 204 +/- 15.9 min and 455 +/- 30.0 min after the 30, 45 and 60 min exercise bouts. Tympanic temperatures were stable at 38.6 degrees C after approximately 30 min of exercise, but all had fallen to resting conditions approximately two hours post-exercise. The correlation between core temperature and EPOC, and RER and EPOC, was r = 0.64-0.75 and r = 0.86-0.89, respectively. These data emphasize the importance of extending the work time for elevating the energy cost during and post-exercise, and suggest that the EPOC can be explained in part by the effects of elevated temperature and metabolic substrate.

Enhancement of exercise performance with inhaled albuterol.

Abstract: The use of bronchodilators in athletic competition has allowed asthmatics to participate successfully in competitive events. Little information exists regarding possible bronchodilator use by non-asthmatic competitive athletes. Fifteen non-asthmatic cyclists participated in a double-blind, randomized, cross-over protocol involving a simulated race, i.e., one-hour heavy continuous exercise (minute ventilation (VE) 81 L/min BTPS) followed by maximal effort workload to exhaustion, with/without prior inhalation of albuterol to see if their exercise performance would be acutely altered. Each study day metabolic parameters were obtained four times. Pulmonary function tests were performed prior to and after the inhalant (albuterol/placebo) and following exercise. There was a significant increase in forced expiratory flow parameters following albuterol. Although not significant, oxygen uptake (VO2) and VE were smaller during the one-hour submaximal test following albuterol and VO2max and VEmax were higher. There was an increased ride time (196 vs. 159 s; p less than 0.05). Albuterol may provide a competitive advantage for non-asthmatic athletes who might use it.

A survey of the race profiles of cyclists in the pursuit and kilo track events.

Abstract: A survey was made of national- and international-calibre men and women track cyclists who rode in three separate world-class competitions on the Argyll Velodrome, Edmonton, Canada Race profiles were obtained from 222 riders who competed in the pursuit and 1000 m time trial (kilo) events Mean lap times (MLT) and optimal race profiles (ORP) were constructed, and served as the bases of comparison between top- and bottom-ranked riders The survey showed that riders whose race profile failed to approximate the ORP always lost to riders whose race profile did so The most likely cause of poor race performances is the inefficient use of the cyclists' anaerobic energy resources

Sequencing of endurance and high-velocity strength training.

Abstract: To compare two sequences of endurance (E) and high-velocity resistance (HVR) training, sixteen male oarsmen were separated into Group ES which trained endurance prior to strength and Group SE which trained strength prior to endurance. The endurance program consisted of up to 60 min a session, five days a week for five weeks. HVR exercise was conducted on 12 stations of variable resistance hydraulic equipment, four sessions per week for five weeks. Endurance training significantly improved VO2max and submaximal heart rate and blood lactate responses in both groups regardless of the sequence followed. HVR training improved VO2max in group SE only and had no effect on submaximal response to exercise. Peak torque increases for knee extension and flexion with HVR training were greater in group SE than group ES. These results show that organizing strength and endurance training into sequential programs can influence the physiological adaptation to training.

Decision styles and coaching effectiveness in university soccer.

Abstract: The Normative Model for Decision Styles in Coaching (Chelladurai and Haggerty, 1978) was empirically tested using Canadian Intercollegiate (CIAU) soccer teams. The subsequent utility of the model's prescriptions for optimizing decision styles of soccer coaches was seriously questioned. Only 33% agreement was found with the model's prescriptions for both CIAU coaches and their athletes. Neither coaches nor athletes were particularly inclined to use delegation in decision making. Athletes, more than their coaches, preferred consultative styles. In support of research findings from business and industrial settings, there was evidence to suggest that high congruence scores between a coach's decision styles and those preferred and perceived by athletes, could predict athlete perceptions of coaching effectiveness. Language: en

Regulation of skeletal muscle glycogenolysis during exercise.

Abstract: Muscle-glycogen breakdown during exercise is influenced by both local and systemic factors. Contractions per se increase glycogenolysis via a calcium-induced, transient increase in the activity of phosphorylase a, and probably also via increased concentrations of Pi. In fast-twitch muscle, increases in the AMP and IMP levels may increase phosphorylase activity. The rate of muscle-glycogen breakdown during exercise depends on the pre-exercise glycogen concentration and is also influenced by hormones. Insulin may inhibit glycogen breakdown, whereas epinephrine enhances the rate of glycogen use in contracting muscle by increasing the phosphorylase a activity via increased cyclic AMP production. The availability of blood-borne substrates may also influence muscle glycogenolysis and, therefore, exercise performance.

A study of dietary patterns of elite Australian football players.

Abstract: This report describes the dietary patterns of 56 elite Australian Rules football players. Data collected included an anthropometric profile, training information, and measurements of haemoglobin and blood lipids. Information on dietary practices, for training and game preparation, was collected by interview and food diary. Analysis of training diets showed a mean energy intake of 14.2 MJ/day (0.17 MJ/kg/day). Mean protein intake was 126 g/day (1.5 g/kg/day). The proportions of dietary energy contributed by the macronutrients were carbohydrate, 44%; fat, 37%; protein, 15%; and alcohol, 4%. Mean daily intake of selected vitamins and minerals from food sources was: retinol activity, 1439 mg; thiamin, 1.7 mg; riboflavin, 2.8 mg; niacin equivalents, 45.1 mg; vitamin C, 139 mg; iron, 19.6 mg; and calcium, 1016 mg. Carbohydrate intake was considered low, but overall intake of nutrients studied was adequate. Language: en

Racial/ethnic variation in the motor development and performance of American children.

Abstract: The literature on the motor development and performance of American children from several racial and ethnic groups is reviewed. The evidence suggests that Black infants are advanced in motor development during the first two years of life, and that Black children of school age, particularly boys, perform consistently better than White and Mexican-American children in running speed (dashes) and the vertical jump, with somewhat less consistent results for the standing long jump and softball throw for distance. In contrast, differences in the motor development and performance of Mexican-American and White children are generally inconsistent and slight. Environmental factors are most often cited as underlying racial or ethnic variation, but have not been systematically investigated. A biocultural approach is essential if an understanding of racial and ethnic variation in motor performance is to be attained.

Racial variation in physique and body composition.

Abstract: Racial variation in physique and body composition are of interest to sport scientists because these characteristics may be related to athletic performance, fitness, strength and injury. There is clearly variation among groups in mean somatotypes and the sitting height-stature relationship. Although differences are often emphasized, racial group distributions of variables describing physique often overlap to a considerable extent. Environment may be a factor in group differences in physique. Consistent Black-White differences are found in mean levels of variables related to bone mineralization, with Blacks exceeding Whites. It may be that the lean body mass of Blacks is of greater density than that of Whites. Gross morphological variation among groups is probably only a concomitant of variation in performance rather than a determinant of performance.

Eccentric and concentric torque and power of the knee extensors of females.

Abstract: The purpose of this study was to compare differences in eccentric and concentric peak torque and power measurements of knee extensors at different velocities. The subjects included 21 females between the ages of 19 and 28, who had no history of knee pain or abnormality. Eccentric and concentric contractions of the knee extensors of the dominant leg of each subject were tested on an isokinetic dynameter at 60 degrees/s, 120 degrees/s and 180 degrees/s. Eccentric peak torque was greater than concentric at each of the three velocities tested, whereas eccentric power was significantly greater only at the two higher velocities. The lack of change in concentric peak torque between 120 degrees/s and 180 degrees/s contrasted with results of other studies, probably owing to methodological differences. Eccentric torque increased from 60 degrees/s to 120 degrees/s, but decreased again at the highest velocity. Both concentric and eccentric power increased with velocity.

The effects of two physical fitness programs designed for mentally retarded adults.

Abstract: The purpose of this study was to design a systematic program of fitness training that enhances physical fitness of mentally retarded adults in sheltered workshops. The first phase of the study was a six-month program conducted by physical education graduate students while the second phase was four months in duration and led by workshop employees. Instructors followed a manual containing 48 lesson plans that were specifically prepared for mentally retarded participants. The physical fitness programs were evaluated using the Canadian Standardized Test of Fitness. MANOVA results revealed that both the six-month and four-month programs increased the physical fitness of the mentally retarded workers, although cardiovascular endurance improved only as a function of the four-month program.

Racial differences in sports performance.

Abstract: The purpose of this paper is twofold: (a) to present data on racial differences in sport performance and (b) to comment briefly on theories, hypotheses and studies, whether they be biological, psychological or sociological in nature, that have attempted to explain the observed differences. Available data are mainly drawn from studies focusing on American professional sports. The results indicate that Afro-American athletes largely dominate the sport scene in a few sports and across a wide range of performance indicators. Although it is impossible at this time to conclude with satisfaction on the causes of racial differences, sociological explanations seem best to explain the observed performance differentials.

Racial variation in work capacities and powers.

Abstract: Large interindividual variation in work capacities and powers are often reported in the literature. The variations are attributed to such varied factors as age, sex, exercise training, and heredity, among others. Ethnic/racial origin as a putative causal factor of such variations has also been considered. Studies of subjects from various countries report aerobic power generally between 40 and 50 mL O2/kg.min-1, with a mean around 45 mL. Differences between groups are generally small and genuine racial differences in maximal aerobic power are lacking when allowance is made for other factors. There are, on the other hand, differences between racial groups in submaximal work efficiency and endurance performance. These differences, however, appear to result from differences in mechanical efficiency owing to test mode and/or level of habituation to the ergometer. Performances on maximal tests of short duration demonstrate some variation among racial groups, but again differences in mechanical efficiency cannot be ruled out. Thus there does not appear to be valid and reliable evidence to support the concept of clear racial differences in work capacities and powers.

The validity generalization of distance run tests.

Abstract: The validity generalization model was used to examine the generalizability of the validity of distance run tests as measures of cardiorespiratory function. A literature search was conducted to identify studies in which distance run test scores were correlated with VO2 max scores obtained from a stress test on a treadmill. The data base was limited to runs of at least one mile or 9 min and the VO2 max scores expressed as mL.kg-1.min-1. The concurrent validity of distance run tests was not shown to be generalizable across all situations. When the data were analyzed by gender, the validity of distance run tests was more generalizable for women than for men. In the analysis of test scores for boys and girls, the validities appeared to be generalizable, although the results should be interpreted with caution owing to small samples sizes.

Electro-mechanical response times and muscle strength after sleep deprivation.

Abstract: This study examined the effect of 60 h of sleep deprivation (SD) on electromechanical response times (EMRT), maximal voluntary isometric contraction (MVC), rate of force development (RFD), and times required to reach various percentages of MVC, during a maximal voluntary isometric contraction of both the forearm flexors and leg extensors. Eleven male subjects were either sleep deprived for 60 h (E) or performed similar daily activities and slept 7 h per night (C). Performance variables were evaluated at the same time intervals during both conditions. No significant differences were observed between the E and C conditions for EMRT (pre-motor time, electro-mechanical delay, total reaction time) or muscular performance (MVC, RFD). The results suggest that subjects who have undergone 60 h of SD can react as fast, and with as much force, as those who have had 7 h of sleep per night.

Blood pressure in resistance trained athletes

Abstract: Resting systolic and diastolic blood pressures were measured in age-matched bodybuilders (n = 31) and medical students (n = 37). Also, systolic blood pressure and heart rate were assessed during progressive cycle ergometer exercise at 100-200 W. Systolic and diastolic blood pressures at rest and systolic blood pressure response during exercise were comparable in bodybuilders and students. Bodybuilders, however, displayed lower (p less than 0.01-0.001) heart rate at identical power outputs of exercise. Consequently, when considering intergroup differences in muscle mass, circulatory responses were similar in bodybuilders and students. The results of the present study together with other observations suggest that intense long-term strength training, as performed by bodybuilders, does not constitute a potential cardiovascular risk factor.

Biomechanical considerations of the menisci of the knee

Abstract: The menisci of the knee are important structures for maintaining a healthy joint since they absorb shock and prevent rotatory instability. The shapes of the menisci and the orientations of their collagen fibres are naturally suited for bearing weight of the joint. Their shape also allows the tibial plateau contact area to be three times greater, thereby decreasing the stress by up to seven times. The medial and lateral menisci are able to move to different extents as a result of the variable laxities of the adjoining ligaments. Often a meniscus becomes injured and must be surgically removed by either a partial or total meniscectomy. Many meniscal injuries occur during sports activities and are caused predominantly by a twisting motion. A meniscectomy has been shown to have detrimental effects including increased joint laxity, osteoarthritis, and other structural changes. Approximately 25% of those who have had a total meniscectomy must stop or restrict their sports activities.

Ventilatory threshold and training heart rate in exercising cardiac patients.

Abstract: The purpose of this study was to determine the relationship between previously prescribed training heart rates (THR) for patients training for six months or more in a cardiac rehabilitation program (CRP), calculated Karvonen percentage heart rate reserve (THRk), and the ventilatory threshold (VT). In twenty male patients (ages 41-63) with documented coronary heart disease (CAD) [non-medicated] mean training heart rate (THR, 75% HRmax) was determined by a telemetry during training sessions. Incremental treadmill testing for determinations of the gas-exchange VT VOE vs. (VO2, Excess CO2) was performed, and the HR at the VT (VTHR) was determined. VO2max was 35.57 +/- 5.57 mL.kg-1.min-1; the VT, expressed as a percentage of VO2max, was 54.45%. The mean THR (133.8 +/- 13.4 bpm) and calculated THRk (141.1 +/- 9.74 bpm) were significantly greater (p less than .05) than the VTHR (124.8 +/- 15.5 bpm), indicating that VT occurs below intensities determined by other methods.

Genetic basis of racial differences.

Abstract: The purpose of this paper is (a) to present brief historical notes on the concept of race, (b) to define race in the context of evolutionary biology, (c) to quantify the extent of human genetic variation, (d) to estimate genetic differences within and between races, and (e) to comment on the implications of these concepts for racial differences in sport performance. Research shows that genetic variation in gene products and in the non-coding sequence of DNA is quite extensive in humans. Variation is found more frequently in non-coding DNA sequences than in coding exons, and while this variation does not influence the primary structure of the proteins, it may have considerable impact on gene expression. However, much of that genetic variation is shared by all human beings, and only about 10% is specific to races or populations within races. At this time, it is not possible to conclude satisfactorily the significance of these modest racial differences in genetic variation for racial differences in performance. It may turn out that this low level of genetic heterogeneity may have considerable implication for performance.

Sport biomechanics: data collection, modelling, and implementation stages of development.

Abstract: This paper discusses three stages of research development that form an integral part of the total process necessary to attain the biomechanist's goal in sport research. The paper is not intended as a comprehensive review of the areas contained within the three stages but rather as a focusing implement that draws the attention of the reader to selected aspects in the following three stages of sport research development: (a) data collection, (b) mathematical modelling, and (c) implementation. The basic contents of this paper were presented at the annual CASS Conference held in Ottawa in 1986.

Changes in urinary pH following bicarbonate loading.

Abstract: The purpose of this study was to determine the effect of bicarbonate doping on urinary pH following intense exercise Sixty-five university students (14 female, 51 male) were tested in a double-blind fashion on two separate occasions one week apart In random order each subject received a 500 mL bottle containing water, flavour crystals, plus either placebo (P) or sodium bicarbonate (B) in a dosage of 03 gm/kg body weight One hour later following an 800 m run a urine specimen was obtained and analyzed in duplicate on a Corning pH meter Urinary pH was significantly increased in the B condition (P = 617 +/- 06; B = 761 +/- 04; p less than 001) There was no difference between the response of the males (B = 759 +/- 03; P = 614 +/- 06) and females (B = 767 +/- 04; p = 629 +/- 06) The times for the 800 m run were B = 235 +/- 22 s; P = 236 +/- 15 s; p greater than 005 These data indicate that urinary pH may be a suitable parameter for detection of bicarbonate doping

Socio-economic and demographic characteristics of national sport administrators.

Abstract: Data gathered from a larger study of policy making in selected national sport organizations afforded an opportunity to examine certain key characteristics that sport administrators bring to their jobs. These people were characterized as male anglophones in their mid- to late thirties, who had six years of full-time job experience. Almost 40% came from low socio-economic status (SES) backgrounds. About half stated they were bilingual; most of the rest spoke only English. About half of these sport administrators had completed their secondary school education in Ontario; they typically held a university degree in physical education or a related field. These data are discussed in light of their implications for policy making in national sport organizations related to three current issues in sport, namely, the under-representation of females, francophones, and people from low-SES backgrounds. Language: en

[Hematological variations with submaximal long-term physical exercise].

Abstract: The purpose of this study was to determine the effects of cold stress on routine hematologic parameters when subjects are submitted on long-lasting exercise. Eight male subjects, aged 22.7 +/- 1.3 years with a peak oxygen consumption of 54.3 +/- 5.2 mL/kg/min performed, respectively at 20 degrees C and 0 degrees C, a two-hour submaximal cyclergometry at an intensity of 40% of that performed during a previous exhaustive test. A 21-gauge catheter was inserted into an ante cubital vein for collection of the blood samples. Platelets and WBC count was significantly (p less than 0.05) increased during exercise in both 20 degrees C and 0 degrees C environmental temperatures. A slight but not statistically significant increase of RBC, Hb and Hct and a plasma concentration during cold exposure was observed. Indices are unchanged in both experiments. The findings of this study suggest that physical exercise is a major factor inducing hypervolemia and that low thermal environment does not appear to be an effective factor influencing hematologic variables during exercise.

Relationships among self-reported physical activity, aerobic fitness and reaction time.

Abstract: Three age groups were studied: 10-11, 17-18, and 23-24 year-olds. Significant correlations were found between aerobic fitness and physical activity level and between aerobic fitness and reaction time, in the oldest group only. Language: en

A theoretical model of the transition phase in human locomotion

Abstract: In this study we examine the bifurcation of the transition between walking and running. Beuter and Lalonde (1986) have conjectured that the pertinent parameters separating walking and running can be described by a cusp singularity (Thom, 1972). In this model, the unidimensional state space is characterized by support duration and the bidimensional parameter space is characterized by the subject's weight and speed. To test this model eight males walked and ran on a motor driven treadmill at an increasing or decreasing speed with or without additional loads corresponding to 0%, 7% and 14% of their body weight. Velocities corresponding to transitions between the two modes of locomotion indicate that on the average the walk-run transition occurs at higher speed than the run-walk transition illustrating an hysteresis effect. In addition, the average difference between the transitions decreases as the load increases [mean 0 = 0.235 m/s, +/- 0.09 m/s, mean 7 = 0.104 m/s, +/- 0.07 m/s and mean 14 = 0.041 m/s, +/- 0.06 m/s] corresponding to an F ratio of F = 2.72, 0.05 less than p less than 0.1. A comparison of the differences in transition velocity at 0% and 14% is statistically different (t = 2.8, p less than 0.025). These results tend to support the existence of an elementary cusp singularity separating the two locomotion modes and suggest that the mechanisms controlling these transitions can be described by a hysterisis cycle and a small number of parameters.

Maximal aerobic power after competitive marathon running.

Abstract: We evaluated the ability of a group of male runners (n = 4) to do maximal and submaximal exercise before and after they ran a competitive marathon (42.2 km) race. VO2max was determined 3 to 6 times in each runner, on alternate days, 1-4 weeks prior to the race, and again an equal number of times, once the runners had recovered from muscle soreness (avg. 7 days) after the race. Each test consisted of a 10 min treadmill walk (8.6% slope, 94 m.min-1 [3.5 miles.h-1]) followed by a 5 min run (8.6% slope, 188 m.min-1 [7 miles.h-1]). After this time, the speed was increased 10 m.min-1 every minute until exhaustion. No differences in VO2 were observed during submaximal exercise, and no reduction in VO2max occurred. One runner, however, exhibited a substantial and consistent increase in VO2max after the marathon (73.6 +/- 1.5 (SE) to 79.9 +/- 0.7 mL.kg-1.min-1, p less than 0.05). Treadmill exercise-induced increases in hematocrit, blood hemoglobin, and plasma protein, cortisol, lactate and norepinephrine concentrations were unaltered after the marathon. We conclude that, following a period of sufficient recovery from muscle soreness, oxygen delivery and utilization mechanisms remain intact after marathon running.