Variability of a set of hemodynamic parameters in young female and male athletes and nonathletes

Regulation of hemodynamics in young subjects was studied via estimating the variability of circulatory parameters. Slow-wave hemodynamic parameters and heart rate variability were shown to be individual-specific.     

Motor and autonomic asymmetries in athletes with different specializations and nonathletes: Communication 2

Data on changes in the electrical activity of paravertebral muscles, autonomic indices, and the lateral organization profile arising during training in subjects with different patterns of physical exercise are presented.     

Skeletal muscle enzymes and fiber composition in male and female track athletes.

Muscle samples were obtained from the gastrocnemius of 17 female and 23 male track athletes, 10 untrained women, and 11 untrained men. Portions of the specimen were analyzed for total phosphorylase, lactic dehydrogenase (LDH), and succinate dehydrogenase (SDH) activities. Sections of the muscle were stained for myosin adenosine triphosphatase, NADH2 tetrazolium reductase, and alpha-glycerophosphate dehydrogenase. Maximal oxygen uptake (VO2max) was measured on a treadmill for 23 of the volunteers (6 female athletes, 11 male athletes, 10 untrained women, and 6 untrained men). These measurements confirm earlier reports which suggest that the athlete's preference for strength, speed, and/or endurance events is in part a matter of genetic endowment. Aside from differences in fiber composition and enzymes among middle-distance runners, the only distinction between the sexes was the larger fiber areas of the male athletes. SDH activity was found to correlate 0.79 with VO2max, while muscle LDH appeared to be a function of muscle fiber composition. While sprint- and endurance-trained athletes are characterized by distinct fiber compositions and enzyme activities, participants in strength events (e.g., shot-put) have relatively low muscle enzyme activities and a variety of fiber compositions.     

Effects of sports training on sleep characteristics of Asian adolescent athletes

Adolescents are predisposed to poorer quality of sleep and experience shortened sleep durations, with these trends being more pronounced amongst Asians. Even though sleep is crucial for athletic recovery, there is a dearth of the literature on the sleep patterns of Asian adolescent athletes. The purpose of this study was to examine the effects of different intensities of sports training on sleep patterns in adolescent athletes, and to describe novel sleep data and daytime sleepiness amongst Asian adolescents who were high-level athletes. Those athletes (age 14.8 ± 0.9 years) in higher-intensity sports showed significantly more deep sleep, less light sleep and waketime after sleep onset. Actigraphically determined bedtimes and waketimes were significantly delayed on weekends, when mean total sleep time was also significantly longer. There was a large effect for an increased daytime sleepiness in high-intensity sport athletes. These findings highlight the phenomenon of social jet lag in Asian adolescent student-athletes.     

Echocardiographic characteristics in adolescent junior male athletes of different sport events

The purpose of this study was to examine the effects of different sport activities on cardiac adaptation. Echocardiographic data of 137 athletes and 21 non-athletes were measured and compared in two age groups 15-16 and 17-18 years of age. Athletes belonged into three groups according to their sports activity (endurance events, power athletes, ball game players). The observed variables were related to body size by indices in which the exponents of the numerator and the denominator were matched. Left ventricular hypertrophy was manifest in all athletic groups. Power athletes had the largest mean left ventricular wall thickness (LVWTd) in both age groups. In the older age group differences between the athletic groups were smaller, but the endurance and power athletes had significantly higher wall thickness. Left ventricular internal diameter (LVIDd) was the largest in the endurance athletes, while mean relative muscle mass (LVMM) was the largest in the power athletes. LVMM of the older endurance athletes was significantly larger. Muscular quotient (MQ) was the highest in the endurance athletes; in the 17-18-year group there was no inter-event difference. Bradycardia was most manifest in the endurance athletes and ball game players, power athletes had higher resting heart rates than non-athletic subjects. It can be inferred that endurance training induces firstly an enlargement of the left ventricle what is then followed by an increase of muscle mass. In the studied functional and regulatory parameters no difference was found between the athletic and non-athletic groups.     

Importance of sports during youth and exercise barriers in 20- to 29-year-old male nonathletes differently motivated for regular physical activities

The number of sedentary young adults has dramatically increased in past decades, and sedentary lifestyles are adopted at an increasingly earlier age. Little is known about barriers or predictors to (re)initiate regular physical activity in this group. The purpose of the study is to (a) identify subgroups in nonathletes differing in their amenability to physical exercise, (b) to analyze them for differences in barriers and intention to exercise, and (c) compare importance of sports during youth in nonathletes to trained peers. Using a health and fitness questionnaire 589 nonathletes were queried in the cross-sectional survey and compared with 270 trained peers. Athletic abstainers (A), lower (L), and higher (H) motivated nonathletes were separated based on previous engagement in sports. Of the nonathletes, 54.7% reported only 1 barrier to exercise. Although this feature was most prominent in H (71.5%), the other groups showed significantly more barriers and a broader distribution. Similar characteristics but minor differences were observed for perceived importance of sports during youth. The most significant differences between athletes and nonathletes emerged enquiring the attitude and activity of the parents. The majority of nonathletes (72.8%) indicate their intention to exercise in the future. Their intention differed significantly in H (88.1%), L (76.1%), and A (59.1%). However, there are good reasons to doubt that most of those intending nonathletes will actually become physically active. Even in the analyzed narrow age range of men different motivated groups of nonathletes were found. Because of the differences in receptiveness and approachability health promotion policies may not only consider the often recommended tailored interventions but also carefully designed incentive programs.     

Difference in isokinetic torque acceleration energy of the rotator cuff: competitive male pitchers versus male nonathletes

Rotator cuff function is critical to the overhead athlete. Rotator cuff power is felt to be important in the overhead athlete during the throwing motion. Little research exists regarding torque acceleration energy (TAE) in overhead athletes. Twenty-five males were divided into 2 groups consisting of overhead athletes (pitchers) (n = 12) and nonoverhead athletes (controls) (n = 13). All participants were given a concentric velocity spectrum isokinetic test at speeds of 60 degrees (1.05 r), 180 degrees (3.16 r), and 300 degrees.s(-1) (5.26 r) to both the dominant and nondominant shoulder internal and external rotators. Significant differences were found for all internal rotator TAE scores (p = 0.000-0.016), at each of the 3 velocities, when comparing dominant to nondominant arms of both overhead athletes and nonoverhead athletes. Only 60 degrees.s(-1) (1.05 r) was found to be different during external rotation TAE testing of the overhead athletes (p = 0.027) but was not found in the control subjects. Post hoc analysis revealed no differences between dominant or nondominant TAE scores when comparisons were made between overhead athletes and controls. Results may reveal that power of the rotator cuff muscles may not be a critical component of the overhead throwing motion.     

Skeletal muscle properties and performance in elite female track athletes

Selected biochemical and physiological properties of skeletal muscle were studied in light of performance capabilities in 24 elite female track athletes. The feasibility of quantifying end point histochemistry and relating oxidative staining density (reduced nicotinomide adenine dinucleotide diaphorase: NADH-D) to whole body maximal oxygen consumption (VO2 max) was also investigated, while muscle fiber types, classified according to alkaline APTase stains, were studied and related to muscle oxidative capacity (succinate dehydrogenase: SDH), VO2 max and "in vivo" torque-velocity properties. Muscle biopsies were taken from the vastus lateralis of each subject and maximal knee extensor torques were recorded at 30 degrees from full extension at four selected velocities. While results confirm earlier reports on skeletal muscle properties and performance it was concluded that end point histochemistry could be reliably quantified and that an "oxidative" stain such as NADH-D correlates extremely well with VO2 max (r = 0.86, p less than 0.001) whereas correlations between % slow twitch fibres (Alkaline ATPase stain) and VO2 max were lower (r = 0.44, p less than 0.05). Additionally, as knee extension velocity increased from 0-1.7 rad x s-1 angle specific extensor torque production did not decline as observed in vitro and pentathletes displayed significantly larger torques at all velocities when compared to the other athletes. These data confirm that while myofibrillar ATPase staining correlates with force-velocity properties of muscle, VO2 max is better correlated with quantified oxidative staining.     

Skeletal growth in school children: maturation and bone mass

Skeletal growth and development was evaluated in 322 white children (age 6 to 14) using three different methods: (1) ¹²⁵I photon absorptiometry, (2) compact bone measures on radiographs, and (3) Greulich-Pyle skeletal age from hand-wrist radiographs. Bone mineral content, measured by photon absorptiometry, increased at an incremental rate of about 8.5% each year. Skeletal age was a poor predictor of skeletal status, i.e., bone mineral content (14% error), and did not decrease the predictive error substantially more than did chronological age. Gross morphology (height and weight) was in fact a better predictor of bone mineral content than were skeletal age, chronological age, and radiographic morphometry. Skeletal age deviations were correlated with deviations in body size. A bone mineral index was devised which was independent of body size and this index was also independent of skeletal age. Skeletal age is imprecise (3 to 6 months error) and the range of variation in normal children (13 months) overlaps the maturational delay of the malnourished and diseased. The difficulties in using skeletal maturation are discussed and it is suggested that particular maturational indices be used which better indicate skeletal growth than does a composite skeletal age.     

Plasma lecithin: cholesterol acyltransferase activity in elite athletes from selected sports

The activity of lecithin: cholesterol acyltransferase (LCAT) and the plasma lipoprotein concentrations of elite athletes from 8 selected sports (volleyball, judo, sprinting, wrestling, throwing, cycling, water polo and tennis) were determined and compared with those of a sedentary control group. Plasma LCAT activity levels in the athletes were significantly 2.2-7.0 times higher than in the controls in most sports (p less than 0.01). Judo, sprinting, wrestling and throwing had comparable LCAT values while tennis, volleyball and cycling were considerably higher. HDL-C concentration was significantly higher than controls in the water polo (p less than 0.05), cycling and volleyball (p less than 0.01) groups. Percentage lipoprotein distribution in the athletes in all sports except tennis, throwing and wrestling were similar to the controls. The differences among groups in LCAT activity may be related to the effect of physical exercise and training adaptations to lipid metabolism. This may be of importance when judging the benefit of exercise for atherosclerosis protection.