Showing papers in "Journal canadien des sciences du sport in 1991"

Table of nonprotein respiratory quotient: an update.

Abstract: The purpose of this paper is to point out some limits and inconsistencies in the table of nonprotein respiratory quotient that is universally used. This table, developed by Lusk in 1924, was derived from biochemical and physical data that are now outdated. A new table of nonprotein respiratory quotient, consistent with modern chemical and physical data, is proposed. The revised table is based on (a) the average composition of human triacylglycerol stores, (b) energy potential of fatty acids and glucose, and (c) the volumes occupied by one mole of oxygen or carbon dioxide (which are not ideal gases) under STPD conditions.

Activity profile of competition soccer.

Abstract: In order to study the movement pattern of soccer players, 14 top-level players were filmed during several competitive matches. In addition, the relationship between the observed activity during match play and blood lactate values was examined. The mean distance covered during competitive matches was 10.80 km, and the average individual difference between matches was 0.92 km, with no difference in regard to high intensity activities. Midfielders covered a 10% longer (p less than 0.05) distance (11.4 km) than defenders and forwards, with no difference concerning high intensity running. There was a significant correlation (r = 0.61, p less than 0.05) between the amount of high intensity running during the match and lactate concentration in the blood. The results suggest that high intensity running can be used for making comparisons in soccer and that the interpretation of blood lactate in soccer is limited to giving an indication of the type of activity that has been carried out a few minutes before sampling.

Physical activity and the immune system.

Abstract: Methods of examining immune function include a charting of susceptibility to infections, differential blood counts or lymphocyte counts, and measures of cell proliferation and immunoglobulin synthesis in response to external mitogens. The reported acute response to exercise is transient and quite variable, depending upon the type of exercise, the immunological methodology used, the intensity of effort relative to the fitness of the individual, and the timing of observation. A leucocytosis, a granulocytosis, a small lymphocytosis, and a decrease in the proportion of T to B cells reflect mainly changes of blood volume, demargination, and migration of cells. Lymphocyte subsets show a decreased helper/suppressor cell ratio and an increase of natural killer cells. Because of the lymphocytosis, mitogens induce an increased overall cell proliferation, but proliferation for a given number of cells is decreased. Prolonged exercise leads to a decrease of serum and salivary immunoglobulin levels. Soluble factors such as interleukin-1 and interferon are increased by a bout of exercise. Cross-sectional comparisons and training experiments suggest that under resting conditions well-conditioned individuals show some lymphocytosis, increased natural killer cell activity, higher levels of interleukin-1, and possibly an enhanced reaction to mitogens. Moderate training does not greatly change exercise responses at a given fraction of maximal effort. Excessive training suppresses immune function, but the changes are small, variable, and thus difficult to relate to overtraining. Moreover, because of their transient nature, they have only a limited influence upon the risks of infection or cancer.

Measures of organizational effectiveness of Canadian national sport organizations.

Abstract: This study of national sport organizations (NSOs) investigated the interrelationships among (a) administrators' perceptions of the effectiveness of the processes of organization, decision making, and personnel relations; (b) administrators' job satisfaction; and (c) Sport Canada ratings of NSOs in high performance, domestic sport, and combined categories. The subjects, 153 volunteer and 84 professional administrators of the 51 NSOs in Ottawa, were grouped on the basis of work status (volunteer/professional) and Olympic status (Olympic/non-Olympic). The four subgroups did not differ in levels of job satisfaction. Volunteer administrators viewed their respective NSO's processes more favourably than did the professional administrators. Higher ratings of decision making and personnel relations related positively to higher levels of job satisfaction. There was minimal association between Sport Canada ratings and administrators' job satisfaction or their perceptions of process effectiveness.

Voluntary and reflex responses to fatigue with stretch-shortening exercise.

Abstract: The effects of 50 depth-vertical jumps (DJ) on counter-movement vertical jump (CMJ), squat jump (SJ), and DJ, isometric knee extension force (MVC), and patellar tendon response were examined in 12 men. There was no reduction in the height of the 50 DJs, but the contact time lengthened by 16%. Height of CMJ and DJ did not change after the 50 DJs, but the activity duration of the leg muscles averaged 13.2% longer. Conversely, height of SJ declined by 11.3%. MVC decreased by 20.1%. No changes occurred in reflex latency and peak-to-peak duration of the compound muscle action potential (AP), but reflex time, AP duration, and AP amplitude increased by 6.4, 6.1, and 23.3%. Thus, subjects compensated for the loss of voluntary force by lengthening the activity duration of the prime movers, potentiating muscle fiber action potentials, and/or enhancing muscle spindle sensitivity.

A kinematic analysis of walking and physical fitness testing in elderly women

Abstract: Walking ability and physical fitness were assessed in 57 elderly Japanese women. Self-selected walking velocity at normal and fast speeds decreased markedly after age 60. The older age groups exhibited significant reductions in the lower limb joint displacements, due particularly to decreased angles at toe-off. The angular velocity of ankle plantarflexion during the stance phase declined markedly with age. A decrease in toe elevation during the swing phase and an increase in stance time in the process of aging suggested an increasing risk of stumbling over obstacles. Reductions in walking parameters with age correlated significantly with aspects of physical fitness tested, especially with items related to neuromuscular functions.

Circadian rhythm in anaerobic power and capacity.

Abstract: Anaerobic power and capacity were measured in nine college-age men at four different times of day: 03.00 h, 09.00 h, 15.00 h, and 21.00 h. Modified Wingate tests were performed against a common resistance of 5.5 kg (0.074 +/- 0.004 kg per kg body mass). Peak power was defined as the highest power output during a 5-s period in the test, and anaerobic capacity was defined as the total external work during the 30-s test. Peak power tended to differ across testing times (F = 2.50, p = .10), with the mean at 21.00 h about 8% higher (p less than .05) than at 03.00 h. Anaerobic capacity differed across the times of day (F = 9.58, p less than .01), with the means at 15.00 h and 21.00 h about 5% higher (p less than .05) than at 03.00 h and 09.00 h. These results suggest that there are circadian rhythms in anaerobic power and capacity.

Physiological characteristics of elite female basketball players.

Abstract: Successful performance in international basketball competition requires an appreciation of the physical demands of the sport and the capacities of the team to respond to those demands. Optimal performance now requires a combination of technical and tactical abilities as well as a high degree of physical fitness. The objectives of this study were to assess physiological components considered important to game performance in players selected to the national team roster in 1988 or 1989, and to use this information to describe the team and positional profiles. Data obtained from maximal treadmill tests, anthropometry, sprints, isokinetic dynamometry, and other tasks reflected those qualities required of elite players. In relation to previously reported data, the athletes were generally taller and heavier and had higher maximal aerobic power than international and college players of 7 to 10 years ago. The data can also be used to identify target standards for current and prospective team members.

Gains of cardiorespiratory fitness with arm-crank training in spinally disabled men.

Abstract: Cardiorespiratory responses to four patterns of arm-crank training (thrice weekly sessions at 50 or 70% of peak oxygen intake, 20 or 40 min per session) were examined over 8, 16, and 24 weeks in 24 initially inactive subjects with paraplegia. Training was associated with a significant increment of the peak oxygen intake during arm-crank tests except in control subjects and those combining a low intensity (50% of peak) with short-duration training (20-min sessions). There were associated increases in cardiac stroke volume, as assessed by a carbon dioxide rebreathing technique during submaximal exercise. It is suggested that the performance of inactive wheelchair users is limited by a pooling of blood in paralysed regions, with a reduction of cardiac preloading; nevertheless, substantial gains of performance are possible through prolonged arm-crank exercise of moderate intensity.

Adolescents' sporting and leisure time physical activities during their 15th year.

Abstract: Participation in physical activity may influence health outcomes, so its quantification is important. There is little data on adolescent physical activities. Recall of physical activity in the preceding year was obtained from a birth cohort of 799 fifteen-year-old adolescents in New Zealand using a modified version of the Minnesota Leisure Time Activities Questionnaire. Mean total participation times were relatively high, with 612 hrs/year (1.68 hrs/day) for males and 401 hrs/year (1.1 hrs/day) for females. Individual total participation ranged from less than a minute to 6.5 hrs/day. Over 10% more females than males reported netball, equestrian activities, and dancing, and at least 10% more males reported cricket, rugby, fishing, soccer, squash, golf, and surfing. Ranked by mean participation time, equestrian activity was highest for females and walking was highest for males. Cycling and swimming represented the largest proportion of total group participation time. The sample will be followed up at age 18 years. Language: en

Adaptations to endurance and low velocity resistance training performed in a sequence.

Abstract: The purpose of this study was to examine the effects of two different sequences of the same two training programs on strength and endurance adaptations. One group completed 5 weeks of low velocity resistance (LVR) training prior to 5 weeks of endurance training (Group SE) while the other group (ES) completed the opposite sequence. Endurance training and resistance training resulted in anticipated increases in aerobic endurance measures and strength, respectively, regardless of the sequence followed. Some maintenance of strength was observed during subsequent endurance training in Group SE. However, the improvements in peak VO2 and submaximal exercise responses that occurred after endurance training in Group ES were not maintained with subsequent LVR training. This investigation suggests that conducting LVR training prior to endurance training may be more beneficial if resistance and endurance training are performed in a sequence.

Anabolic steroids in sport.

Abstract: The use of androgenic-anabolic steroids (AAS) for enhancing athletic performance and body image is widespread. An increasing number of elite and recreational athletes of varying ages and athletic pursuits are using AAS. Sophisticated patterns of AAS use are supported by unethical and illegal distribution channels. Various testosterone-derived preparations attempt to manipulate pharmacological characteristics in an effort to maximize anabolic potential while minimizing androgenic effects. Although anecdotal and theoretical information suggests that AAS have positive ergogenic properties, the experimental evidence is equivocal. In addition to the ethical and legal implications of using AAS, there are diverse, though often reversible, medical and behaviour ramifications. In an effort to control and discourage AAS use, relevant sport governing bodies have implemented various testing and educational programs with undetermined success.

Left ventricular functional response to moderate and intense exercise.

Abstract: The left ventricular (LV) volume and ejection fraction (EF) response to upright exercise was assessed on 15 normal subjects during cycle ergometry Measures of cardiac function and gas exchange were made at rest, at 85% of the ventilatory anaerobic threshold (VAT; WL1), and at peak exercise (WL2) EF increased from rest (58 +/- 12%) during WL1 (66 +/- 10%), reaching significantly higher values at WL2 (69 +/- 8%; p less than 05) End-diastolic volume increased from rest during WL1 (136 +/- 36 ml vs 118 +/- 32 ml; p less than 05), becoming significantly higher than rest during WL2 (141 +/- 41 ml) End-systolic volume was unchanged from rest (51 +/- 25 ml) during submaximal exercise (50 +/- 20 ml), but it decreased significantly during WL2 (44 +/- 21 ml; p less than 05) The systolic pressure/end-systolic volume ratio increased from 30 +/- 17 (rest) to 58 +/- 30 at WL2 (p less than 05) These results suggest that the Frank-Starling mechanism is operative throughout exercise, particularly during exercise below the VAT LV performance after the VAT is further augmented by increased contractility with continued, yet diminished, utilization of the Frank-Starling mechanism

Time-motion analysis of and heart rate responses to amateur ice hockey officiating.

Abstract: The physical activity of referees (n = 4) and linesmen (n = 6) was analyzed from videotapes of four varsity hockey games to determine the frequency, average duration, and total time spent in each of six activity categories. The average duration of activity was low while frequency of occurrence was high. Low intensity activities occupied 96% of total time for referees and 94% of time for linesmen. Heart rate responses were recorded every 5 seconds and synchronized to the videotapes for all referees and 5 linesmen. Heart rates were above 70% of maximum for 70% of the total ice time, which was greater than expected for the observed physical activity. Psychological stress during the course of a varsity hockey game could contribute to the high heart rate responses. It is concluded that training to increase aerobic fitness is an important aspect of ice hockey officiating to increase resistance to fatigue and aid in stress management.

Ben Johnson and the use of steroids in sport: sociological and ethical considerations.

Abstract: This paper examines from a sociological and an ethical standpoint the problem of steroids in sport and competition. After a sociological analysis of some key ideological, social, political, and economic issues related to drugs in sport, we address the question of whether ethically we wish these developments to continue along the same path. A final analysis of the nature of the "authentic practice" makes the distinction between the practice itself with its intrinsic search for excellence and the organizations that sustain the practice but are essentially and necessarily concerned with extrinsic rewards from winning--money, power, status. Priorities have to be reexamined in light of certain fundamental ethical principles.

Measuring the reliability of a computer-aided systematic observation instrument.

Abstract: The inter- and intraobserver reliabilities of data collected by observers trained in the use of the coach analysis instrument (CAI) are reported. The CAI is part of the computerized coaching analysis system (CCAS). The CAI collects data related to the learning environment created by the coach in a team/sport practice situation. Both inter- and intraobserver reliabilities are reported for each of the instrument's seven dimensions as well as for the overall instrument. The reliability measures reported are total percent agreement (T) and Cohen's kappa (K). The results indicated that, although the overall coaching analysis instrument reached a T value of 90.8%, it failed to meet the 80% level for the K measure (K = 78.5%). A dimension by dimension examination of the data was undertaken to determine the reasons for these results and it was revealed that the problem was associated with three specific dimensions of the instrument.

Muscle Na,K-pump dysfunction may expose the heart to dangerous K levels during exercise.

Abstract: During exercise, potassium leaks out of muscle cells and interstitial potassium concentration may rise to 15 mmol/l. Potassium is then in part transported back to the cells by the Na,K-pump. The leak of potassium from working human muscles can be calculated to 15 mumol/g/min. Human muscles contain 300 pmol/g wet weight Na,K-pumps and have a maximum capacity for potassium uptake of 5 mumol/g/min. At rest only a small percentage is used, but during maximum stimulation the entire capacity can probably be used. During exercise, total potassium leakage from the human muscle pool is 400 mmol/min and maximum active reuptake capacity is 100 mmol/min. ECV contains only 50 mmol potassium. During heavy exercise the capacity for active potassium uptake in muscle pool may be exceeded and interstitial potassium equilibrates with plasma potassium, which then may rise to 10 mmol/l. Training can decrease the rise in plasma potassium during exercise by 0.2-0.5 mmol/l. Variation in muscle Na,K-pump concentration may be associated with changed plasma potassium homeostasis during exercise, which if disadvantageous may be dangerous to the heart.

Profile of sport/leisure injuries treated at emergency rooms of urban hospitals.

Abstract: The main thrust of this study was to examine the nature and number of sport/leisure injuries treated in hospital emergency rooms in a large metropolitan city. A total of 244 respondents, or 4% of the total case load in six hospital emergency wards, were treated for sport/leisure injuries during the 1-week survey. The results show that 86.3% occurred to individuals 30 years of age or under, that injuries to males outnumbered those to females by a margin of 3:1, and that 57.5% of those injured were active on a regular basis (i.e., at least once a week). The highest number of sport/leisure injuries (71.5%) occurred from participation in noncontact recreational sports and 61.9% occurred during supervised activities, yet over 55% received no on-site or first-aid treatment. These data suggest a need to promote community oriented safety education and first-aid programs. Language: en

Blood pressure response to exercise in normotensives and hypertensives.

Abstract: Hypertensive patients have lower cardiac outputs and stroke volumes, higher heart rates, and a markedly higher peripheral resistance than normotensive individuals at the same intensity of exercise. Even patients with mildly elevated resting blood pressures have a markedly increased myocardial oxygen demand during exercise; since demand is determined not only by the pressure load but also by the degree of ventricular hypertrophy, three therapeutic inferences may be drawn: (a) Endurance training offers hypertensive patients a means of lowering exercise heart rate, reducing the systolic blood pressure and myocardial oxygen consumption, and also improving physical work capacity. (b) Besides avoiding isometric exercise, due to possible excessive peaks of blood pressure, all patients should be evaluated by ergometric testing before beginning an exercise training programme. (c) If ergometry reveals a marked rise in blood pressure at low levels of exertion, then appropriate antihypertensive medication (beta-blockers, calcium antagonists) should be prescribed prior to training.

Responses to acute exercise and training after cardiac transplantation: a review.

Abstract: Cardiac transplant patients now survive for several years, and the quality of life after recovery from the immediate operation is of increasing interest. The acute response to exercise depends mainly upon an increase of venous return (acting through the Frank-Starling mechanism) and slower chronotropic and inotropic responses to circulating catecholamines. At rest, there is some increase of heart rate and blood pressure, with a low normal cardiac output. During submaximal exercise the stroke volume is greater than normal, but the cardiac output is somewhat reduced, leading to a widening of arteriovenous oxygen difference. Peak heart rate, peak stroke volume, and peak cardiac output are all substantially reduced in the immediate postoperative period. Poor ventricular performance reflects in part an increase of afterloading associated with lean tissue loss. Endurance training restores lean tissue, with associated and probably causally related gains of cardiac function and peak oxygen transport. Exercise prescription after transplantation is commonly regulated by walking distance and pace, ventilatory and blood pressure responses, and ratings of perceived exertion, monitoring for episodes of infection and transplant rejection. There are psychological disturbances immediately following surgery, but again training appears to help ameliorate the mood state. Heterotopic transplants (in which donor and recipient hearts are conserved) generally yield a less satisfactory result than the standard orthotopic procedure. The ventilatory response to exercise is greater for a heart-lung transplant than for a cardiac transplant, but overall functional responses seem similar for the two types of patients. Patients tolerate exercise quite well after cardiac transplantation, and progressive endurance training is a helpful component of treatment in such individuals.

Coach/player relationships in tennis.

Abstract: The present study examined the variables that predict coach/athlete compatibility. Compatibility among a sample of 52 elite tennis coach/player dyads was assessed using a sport adapted version of Schutz's (1966) Fundamental Interpersonal Relations Orientation-Behaviour (FIRO-B), a sport adapted version of Fiedler's (1967) Least Preferred Co-worker scale (LPC), and Chelladurai and Saleh's (1980) Leadership Scale for Sport (LSS). Self-ratings of the quality of the interaction were obtained from both coach and athlete. Multiple-regression analyses using self-rating scores as the dependent measure were carried out to determine which variables best predicted the degree of compatibility. The sole inventory that significantly predicted compatibility was the LSS. More specifically, the discrepancy between the athlete's preferences and perceptions on the autocratic dimension was the best predictor. Implications for tennis coaches and recommendations for future research in this area are discussed.

Angle-specific torques of thigh muscles: variability analysis in 200 healthy adults.

Abstract: This study evaluated the variability of the isokinetic angle-specific torques (ASTs) at 15 and 75 degrees of knee flexion and assessed the relationship between them and the isokinetic peak torque (PT) in 200 healthy adults. The results showed that the value of these AST measurements was lower than of the PT measurements. This was due to larger variability of the AST (male and female coefficient of variation [cv] 34 and 43% in the ASTs vs. 19 and 31% in the PTs); unequal variation in the results between men and women (mean cv 27% in men vs. 34% in women); and fairly poor prediction of the ASTs from the PT (PT accounted for only 39 and 62% for the variation seen in the men's and women's AST results). Furthermore, in regression analysis the standard errors of the estimates were unacceptably high, averaging 26%. AST measurements should not be used routinely.

Effects of exercise training on components of the motor unit.

Abstract: Relatively little is known as to how the motor unit (the motoneurone and its innervated muscle fibres) adapts. Using the model of compensatory overload of the rat plantaris, we have described the complex patterns of adaptation which differ across motor units within a single muscle. These adaptations, measured using histochemical and physiological techniques in combination, emphasize the difficulty of predicting whole muscle responses from those of its constituent muscle fibres and motor units. In addition, they suggest that subtle changes may occur in the way motor units are used during training that are not evident when looking at whole muscles. Evidence of the responses of the motoneurone component of the motor unit to overload is fragmentary; nonetheless, other models of neuromuscular adaptation show the extent to which motor nerves and muscles adapt in a coordinated manner, with functional consequences that may be relevant to the exercise training model. More information on overload-induced changes in motoneurone and muscle properties, how these changes are coordinated, and their functional consequences, is necessary in order to better understand the training model.

Ambulatory blood pressure and Holter monitoring during tennis play.

Abstract: The effect of tennis play on blood pressure, heart rate response, and rhythm disturbances was evaluated in 21 men 39 to 61 years of age (M = 49.5 +/- 6.7 yrs). A Holter monitor was utilized for continuous ECG recording during tennis play and a portable ambulatory blood pressure recorder (Spacelabs) was used to measure blood pressures and heart rates periodically during tennis matches. The results indicated that blood pressure response to tennis (singles), although an activity of moderate aerobic intensity, can exert significant increases in systolic and diastolic blood pressure even in those persons who are normotensive at rest. Excessive body weight, and particularly abdominal deposition, appears associated with an increase in diastolic blood pressure to exercise. Few heart rhythm disturbances of consequence were uncovered. A simple submaximal step test such as the Canadian Aerobic Fitness Test, with ECG monitoring, could assist in detecting those individuals susceptible to an exaggerated blood pressure response and to heart rhythm disturbances at exercise.

Effect of leg length on bench stepping efficiency in children.

Abstract: The effect of leg length on relative oxygen consumption (VO2), heart rate (HR), and minute ventilation (VE) during stepping was examined in 30 boys ages 8-12 years Stepping height was varied to correspond to 30, 40, and 50% of the individual's leg length while maintaining a constant exercise load There were no significant differences in VO2, HR, and VE among the three stepping conditions The effects of knee joint angle, leg length, and the ratio of leg length to body weight were further assessed by comparing the top third and bottom third of the sample when classified on these anthropometric measurements No significant differences were found between the high and low groups when classified according to knee joint angle; however, ventilation was higher for the longer legged subjects and for subjects having a low leg length to body weight index It was concluded that leg length does not influence the physiologic responses of young boys to moderate stepping exercise

The regulation of myosin gene transcription in skeletal muscle: effects of altered functional demand.

Abstract: Perturbations in the activity patterns of skeletal muscle have been used to probe adaptive mechanisms that occur when the function of a muscle is altered. A plethora of information is available concerning the phenotypic changes that occur in the skeletal muscle myosin patterns when the load placed on a muscle is changed. More recently, technological advances in molecular biology have facilitated investigations concerning how these changes at the protein level are mediated via transcription of the genome. The focus of this review will be the recent evidence concerning the regulation of transcription of the myosin isogenes in skeletal muscle. In addition, putative regulatory factors are discussed which may link an alteration in function to altered transcription of the genome.

Measurement of VO2 max with 2 rowing ergometers on the water in a skiff

Abstract: Rowing ergometers are designed to increase testing specificity but have never been validated against measurements obtained while rowing in the water. VO2max of 14 regional and national rowers (7 men and 7 women) from 17 to 30 years of age randomly obtained on two commonly used rowing ergometers, the Concept II (initial load at 40 km/h + 8 km/h increment every 2 min) and the Gjessing Ergorow (initial load at 1 kg + 0.25 kg increment at 28 strokes/min up to 1.5 or 3.0 kg according to sex and 2 sdtrokes/min thereafter), were compared to those obtained while rowing on the water (best VO2 values of three 4-min trials at maximal speed). VO2max values were similar (p greater than 0.05) for the three ergometers (M +/- s: 4.02 +/- 0.90 for the Concept II; 4.15 +/- 0.95 for the Gjessing Ergorow, and 4.04 +/- 0.83 L/min for the skiff). Pearson correlations and standard errors of estimate expressed in %Y were 0.92 and 9.0% (Concept II vs. Gjessing), 0.93 and 7.9% (Gjessing vs. skiff), and 0.96 and 6.1% (Concept II vs skiff). VO2max determination on these two rowing ergometers appears specific and comparable to the one obtained on the water and is also much easier to obtain.

Spinal anaesthesia for day case surgery in sportspersons and sedentary patients.

Abstract: The effects of spinal anaesthesia were investigated in 67 sportspersons and in 128 sedentary patients (average age 31.8 +/- 6.2 yrs). The most frequent complaint in both groups was mild low back pain (27 cases vs. 58). Postspinal headache was severe and disabling, with an incidence of 13.4% in the sportspersons and 21.1% in the sedentary group. The sedentary group also showed a higher incidence of other postanaesthetic problems. Given the high rate of side effects, the young age of the subjects, and their desire to resume work as soon as possible after the operation, spinal anaesthesia is not the best anaesthetic procedure for this age group.