Women's intercollegiate volleyball and tennis: Effects of warm-up, competition, and practice on saliva levels of cortisol and testosterone

In virtually all sports, participants “warm-up” prior to formal competition. Women athletes from a highly ranked varsity college volleyball team and, in a second study, a highly ranked varsity college tennis team gave saliva samples before warm-up, at mid-warm-up (volleyball) or after warm-up (tennis), and immediately after intercollegiate competition. For volleyball and tennis, warm-up was associated with a substantial elevation in saliva levels of testosterone which was carried over through the period of actual competition. Cortisol levels were relatively unchanged during warm-up, but typically rose during competition. Thus, as women prepare for athletic competition by warming up, testosterone levels rise in apparent anticipation of the coming contest and then remain high through the period of play. In volleyball and tennis, after-practice testosterone level was significantly higher than before-practice level, and practice session increases in testosterone (but not cortisol) were positively correlated with increases in testosterone during intercollegiate competition. When practice and competitive play share as yet undetermined key elements, individual differences in this endocrine response to “competition” appear stable across practice and intercollegiate competition.     

Relationships between physical activity and musculoskeletal disorders in former athletes

The purpose of the study was to determine the prevalence and risks for musculoskeletal disorders (MSD) in relation to previous athletic status and current physical activity level in former athletes. Main anthropometric data, sports history, current physical activity and MSD were estimated using a questionnaire in 219 (148 males, 71 females) former athletes (35-75 years old) and 79 controls (33 males, 46 females). According to the previous participation in top-level sports, former athletes were divided into three groups: (a) endurance, n=120 (76 males, 44 females); (b) speed-power, n=57 (43 males, 14 females); (c) team sports, n=42 (29 males, 13 females). The most prevalent MSD among the male and female ex-athletes were back and knee pain. The endurance ex-athletes group (both males and females) had significantly higher risk for the knee problems than the control group (Odds ratio--OR 5.9, 95% CI 1.7-20.00, p < 0.05). Team sports athletes (males and females) showed significantly higher risk for Achilles' tendon injuries (OR 3.19 95% CI 1.19-8.5, p < 0.05) as compared to controls. Back pain did not show any significant associations with previous physical activity and current physical activity level. Current physical activity was significantly associated with a lower risk for the knee and hip pain. Body mass index was positively associated with knee problems. In conclusion, our study results revealed that previous participation in enduranve sports events is associated with a significantly higher risk for knee problems. At the same time current regular physical exercise 6-11 times per month is associated with a lower prevalence of knee and hip problems as compared to those who exercised less than 6 times per month.     

Comparing jumping ability among athletes of various sports: vertical drop jumping from 60 centimeters

Drop jumping performance (DJP) is of high importance in order to achieve sporting performance in both team and individual sports. The purpose of the present study was to compare DJP among athletes from various sports. One hundred thirty-eight male athletes (age: 22.3 +/- 3.6 years, body height: 1.87 +/- 0.08 m, body mass: 81.8 +/- 10.8 kg) from 6 different sports performed drop jumps from 60 cm (DJ60) on a force plate. Results revealed that volleyball players jumped higher (p < 0.001) than other athletes. However, track and field athletes produced higher peak force and higher power output using a shorter upward phase (p < 0.001). Further examination using principal components analysis (PCA) revealed that team sport athletes and single scull rowers exhibited DJP utilizing force and time parameters differently than track and field athletes. Conclusively, DJP was different among athletes of various sports. Furthermore, PCA can be a useful method for evaluating the above mentioned differences and for monitoring drop jumping training programs.     

Incidence of exercise-induced asthma in adolescent athletes under different training and environmental conditions

The aim of this study was to establish if there were differences in the incidence of exercise-induced bronchospasm between athletes in different sports, which take place under different environmental conditions such as open places, closed courses, and swimming pools with similar exercise intensity (football, basketball, water polo) using the free running test. The study included 90 adolescents (3 groups of 30) aged 14-18 years recruited from academies in northern Greece. All the participants were initially subjected to (a) a clinical examination and cardiorespiratory assessment by a physician and (b) free running test of a 6-minute duration and measurement with a microspirometer of the forced expiratory volume in 1 second (FEV?). Only the participants who had measured a decrease in FEV? ≥ 10% were reevaluated with the microspirometer during a training session. The examination of all the participants during the free running test showed that 22 athletes, that is, 9, 8, and 5 of football, basketball, and water polo athletes, respectively, demonstrated an FEV? ≥ 10 drop. Reevaluation of the 22 participants during training showed that 5 out 9 (55%) football athletes, 4 out of 8 basketball athletes (50%), and none of the 5 athletes of the water polo team displayed a drop of FEV? ≥ 10%. Despite the absence of any significant statistical differences between the 3 groups, the analysis of variances did show a trend of a lower incidence of EIA in the water polo athletes. It was found that a football or basketball game can induce EIA in young athletes but to a lesser degree than the free running test can induce. The water polo can be a safer sport even for participants with a medical history of asthma or allergies.     

Influence of acute maximal exercise on lecithin:cholesterol acyltransferase activity in healthy adults of differing aerobic performance

To document the possible influence of a single episode of maximal aerobic stress on the serum lecithin:cholesterol acyltransferase (LCAT) activity in subjects with differing histories of training, two groups of healthy male adults [controls (C), n = 18, 28.6 years, SD 5.2, 50.1 ml.kg-1.min-1 maximal O2 uptake (VO2max), SD 5.3; endurance trained athletes (T), n = 18, 31.4 years, SD 8.8, 65.0 ml.kg-1.min-1 VO2max, SD 2.8] were examined in a maximal aerobic stress test. In addition to the routine assessment of lipid status, LCAT activity was measured immediately before and after exercise. At rest nearly identical LCAT activity values were found in both groups: C 64.4 nmol.ml-1.h-1, SD 16.7 vs T 65.0 nmol.ml-1.h-1, SD 20.9. The post-exercise LCAT values induced by the maximal stress test increased significantly to (C) 95.7 nmol.ml-1.h-1, SD 23.5, +48.6%, P less than 0.001; (T) 83.5 nmol.ml-1.h-1, SD 24.3, +29.1%, P less than 0.01. Neither the pre nor the postexercise individual LCAT activity values showed any significant correlation to the corresponding data on physical performance.     

Throwing velocities, anthropometric characteristics, and efficacy indices of women's European water polo subchampions

Water polo is a team sport characterized by a high-intensity, intermittent activity, where technical and tactical aspect are of a great importance. For that reason, the main aim of this study was to define the anthropometrical characteristics, maximum isometric grip strength, training and competition throwing velocities, and the efficacy indices in female high-level water polo players. A second purpose was to examine the differences between the throwing velocities in training vs. European championships in the water polo female national team. Ten elite trained female water polo players participated in this study. Before the competitive phase of their season, the following measures were taken: standard anthropometry, static and dynamic training throwing velocities, and hand-grip dynamometry. In the competitive phase, efficacy indices, average and maximum throwing velocities from all the participants were also determined. Significant differences (p ≤ 0.05) were found between different training situations and different competitive throwing velocities. We concluded that elite female water polo players modify their throwing velocity depending if the throw is performed during training or competitive situation.     

Retrospective case evaluation of gender differences in sports injuries in a Japanese sports medicine clinic

Background: Although both gender- and sports-specific injuries exist among athletes, gender differences in the types of injuries caused by sports activities, except for anterior cruciate ligament (ACL) injury and anterior knee pain, are not well established.Objective: An observational study with a retrospective case-series design was conducted to investigate gender-specific differences in the types of injuries sustained while engaging in sports activities common to both males and females.Methods: We analyzed injuries sustained during sports activities including basketball, volleyball, tennis, skiing, track and field, and swimming, using data on age, sex, sports activities, activity levels, and sports injuries that had been computerized at our sports medicine (orthopedics) clinic. Inclusion criteria were sports activities that had a record of >100 injuries in total and athletes aged <50 years who were engaging in only 1 sports activity. We determined the absolute number of patients in each category and their percentage (proportion) of our cohort. The proportions of common injuries caused by sports activities were investigated, and gender-specific differences in the types of common injuries caused by sports activities were clarified. The Fisher exact test was used to determine the significance (P < 0.01) of the gender-specific differences in the types of sports injuries.Results: According to our database, during the 14-year period between October 1992 and December 2006, a total of 2989 athletes (1624 males and 1365 females) aged <50 years who engaged in 1 of the 6 sports activities described consulted our sports medicine clinic. The most common sports injuries were ACL injury (14.3%) and knee pain (13.7%), followed by ankle sprain (9.4%), lumbar disc disease (7.0%), meniscus injury (5.1%), stress fracture (2.9%), low back pain (2.5%), patellar tendinitis (2.1%), injury of the medial collateral ligament of the knee (2.0%), lumbar spondylolysis (1.7%), and muscle strain (1.5%). Among these 11 types of sports injuries, a significantly higher proportion of females who engaged in basketball (24.4% vs 10.5%), volleyball (20.5% vs 4.5%), or skiing (41.4% vs 26.5%) presented with an ACL injury, compared with their male counterparts (all, P < 0.001). There was also a significantly higher proportion of females than of males among the track and field athletes who presented with stress fractures (18.7% vs 3.9%; P < 0.001).Conclusion: The findings of this retrospective study suggest that there are gender-specific differences in the types of injuries sustained during sports activities.     

Immune response to exercise in elite sportsmen during the competitive season

Our aim was to evaluate the chronic effects of training and competition during a 4-month season on immune response in professional volleyball players. Players took part in an incremental maximal cycling test at the beginning and at the end of the season. As control group, subjects with regular recreational activity were selected. Blood samples were obtained at rest, immediately after the exercise test, and after 30 min recovery. Volleyball players have similar basal levels of erythrocytes, hematocrit, hemoglobin, and total protein and urate than controls and higher levels of creatinine and activities of AST, ALT, and GGT. Maximal incremental exercise test significantly increased erythrocyte counts, hematocrit, and blood hemoglobin levels in volleyball players. T- and B-lymphocytes significantly increased after exercise test and were maintained high during recovery. Cortisol levels were significantly increased immediately after exercise and during recovery with respect to basal values. Basal and post-exercise cortisol levels were significantly higher at the final of season than at the beginning. Serum levels of immunoglobulins (IgG, IgA, and IgM) and complement fractions (C3, C4) were unaffected by the volleyball season. The IgG and IgM levels were significantly higher after exercise and recovery than basal levels. Maximal exercise test induced an acute phase/inflammatory response characterized by increased circulating lymphocytes, antibody response, and cortisol levels. Competition season increases cortisol concentration indicative of accumulated stress intensity.     

Muscle-contraction properties in overarm throwing movements

On the basis of dynamic and kinematic data, this study identifies the type of muscle contraction in unloaded overarm throwing movements. An unloaded throw or nearly unloaded throw is defined as the throw in which the external resistance is too small (e.g., the team handball, baseball, and water polo throws as well as the tennis and badminton smashes). A special arm-force-measuring apparatus was constructed to imitate an overarm throw. Forty-two subjects were placed into 3 groups: untrained subjects, weight-trained athletes, and team handball players. The measured parameters included the velocity of the initial movement, the release velocity, the velocity of the first 50 milliseconds of the concentric phase, the force value at the moment of deceleration of the initial movement, and the impulse values during the eccentric and concentric phases of the test movement. Statistically significant higher values of the above parameters (p < 0.05) were determined in that test at which the initial speed of movement was higher. Also, the correlation coefficients of the parameters of the initial phase of the throw movement were very high (p < 0.001), especially the parameters related with the movement's first 50 milliseconds. The results support the thesis that the stretch-shortening cycle is the type of muscle contraction in unloaded overarm throws. Furthermore, it is possible to increase the throw velocity by increasing the velocity of the initial movement (i.e., by provoking higher inertia forces).     

Side-to-side comparisons of bone mineral density in upper and lower limbs of collegiate athletes

This cross-sectional study investigated the effects of participation in various sports on side-to-side (contralateral) differences in bone mineral density (BMD) of the upper and lower limbs. The BMD of the arms and legs was measured using dual energy X-ray absorptiometry. The subjects were 184 collegiate athletes, both men and women, who participated in NCAA Division I-A baseball, basketball, football, golf, soccer, tennis, cross-country, indoor/outdoor track, and volleyball. Results revealed greater BMD of the right arms compared with the left arms for all teams, with the most pronounced differences observed in men's and women's tennis and men's baseball. Differences in the lower limbs were less common. No significant differences in lower limb BMD were found in the women. In men, differences in lower limb BMD were found in the football and tennis teams, with the nondominant leg having greater bone mass. Recognition of contralateral differences in bone density may be of particular interest to strength and conditioning professionals as they consider the need to include bilateral and unilateral training programs in an effort to maximize performance and minimize stress-related injuries.     

Body composition and Vo2max of exceptional weight-trained athletes.

The maximal oxygen uptake and body composition of 30 exceptional athletes who have trained extensively with weights was measured. The sample included 3 world record holders, 8 other world class athletes, and 19 national class competitors. The sports represented were shot-putting, discus throwing, body building, power lifting, wrestling, and olympic lifting. Vo2max as determined on a bicycle ergometer by the open-circuit method was 4.6 +/- 0.7 1-min-1 (mean +/- SD) (48.8 +/- 7 ml-kg-1., 56.4 +/- 8.6 ml-(kg LBW)-1). The mean maximal heart rate was 185.3 +/- 11.6 beats-min-1. The subjects attained a work rate of 1,728.2 +/- 223 kpm-min-1 on a continuous progressive bicycle ergometer test and had mean maximal ventilations of 152.5 +/- 27.7 1-min-1 BTPS. Body composition was determined by densitometry. Body weight averaged 96.0 +/- 14.9 kg, with mean percent fat of 13.8 +/- 4.5. The results of this study indicate that exceptional weight-trained athletes are within the normal college-age population range in body fat and of somewhat higher physical working capacity.     

Comparison of posture among adolescent male volleyball players and non-athletes

Due to high training loads and frequently repeated unilateral exercises, several types of sports training can have an impact on the process of posture development in young athletes. The objective of the study was to assess and compare the postures of adolescent male volleyball players and their non-training peers. The study group comprised 104 volleyball players while the control group consisted of 114 non-training individuals aged 14-16 years. Body posture was assessed by the Moiré method. The volleyball players were significantly taller, and had greater body weight and fat-free mass. The analysis of posture relative to symmetry in the frontal and transverse planes did not show any significant differences between the volleyball players and non-athletes. Postural asymmetries were observed in both the volleyball players and the control participants. Lumbar lordosis was significantly less defined in the volleyball players compared to non-training individuals while no difference was observed in thoracic kyphosis. All athletes demonstrated a loss of lumbar lordosis and an increase in thoracic kyphosis. Significant differences in anteroposterior curvature of the spine between the volleyball players and the non-athletes might be associated with both training and body height. Considering the asymmetric spine overloads which frequently occur in sports training, meticulous posture assessment in young athletes seems well justified.     

Acute injuries in soccer,ice hockey,volleyball, basketball,judo, and karate: analysis of national registry data.

OBJECTIVE--To determine the acute injury profile in each of six sports and compare the injury rates between the sports. DESIGN--Analysis of national sports injury insurance registry data. SETTING--Finland during 1987-91. SUBJECTS--621,691 person years of exposure among participants in soccer, ice hockey, volleyball, basketball, judo, or karate. MAIN OUTCOME MEASURES--Acute sports injuries requiring medical treatment and reported to the insurance company on structured forms by the patients and their doctors. RESULTS--54,186 sports injuries were recorded. Injury rates were low in athletes aged under 15, while 20-24 year olds had the highest rates. Differences in injury rates between the sports were minor in this adult age group. Overall injury rates were higher in sports entailing more frequent and powerful body contact. Each sport had a specific injury profile. Fractures and dental injuries were most common in ice hockey and karate and least frequent in volleyball. Knee injuries were the most common cause of permanent disability. CONCLUSIONS--Based on the defined injury profiles in the different sports it is recommended that sports specific preventive measures should be employed to decrease the number of violent contacts between athletes, including improved game rules supported by careful refereeing. To prevent dental injuries the wearing of mouth guards should be encouraged, especially in ice hockey, karate, and basketball.     

Effect of zinc supplementation on hematological parameters in athletes

The hematological effects of oral supplementation of zinc to training athletes are reported in the present study. A total of 30 subjects between 16 and 22 yr of age volunteered to participate in a 4-wk study. They were equally divided into three groups. Group 1 acted as resting controls receiving daily doses of 3 mg Zn/kg body wt. Group 2 was actively engaged in wrestling and exercised for 90–120 min, 5 d a week. Group 3 was also actively engaged in wrestling and exercised for 90–120 min, 5 d a week, but they were supplemented with 3 mg Zn/kg body wt per day. The erythrocyte, leukocyte, and thrombocyte counts and the hemoglobin values of all subjects participating in the study were measured before and after exercise at the beginning and at the end of the 4-wk study period. In all groups, there were no significant differences in the measured parameters before and after exercise. At the end of the supplementation period, the parameters of the subjects in groups 1 and 3 were significantly higher than those of group 2, both before (p<0.005) and after (p<0.05) exercise. These results suggest that zinc supplementation has a positive effect on hematological parameters in athletes.     

Influence of insulin sensitivity and the TaqIB cholesteryl ester transfer protein gene polymorphism on plasma lecithin:cholesterol acyltransferase and lipid transfer protein activities and their response to hyperinsulinemia in non-diabetic men.

Lecithin:cholesteryl acyl transferase (LCAT), cholesteryl ester transfer protein (CETP), phospholipid transfer protein (PLTP), and lipoprotein lipases are involved in high density lipoprotein (HDL) metabolism. We evaluated the influence of insulin sensitivity and of the TaqIB CETP gene polymorphism (B1B2) on plasma LCAT, CETP, and PLTP activities (measured with exogenous substrates) and their responses to hyperinsulinemia. Thirty-two non-diabetic men without hyperlipidemia were divided in quartiles of high (Q(1)) to low (Q(4)) insulin sensitivity. Plasma total cholesterol, very low + low density lipoprotein cholesterol, triglycerides, and apolipoprotein (apo) B were higher in Q(4) compared to Q(1) (P < 0.05 for all), whereas HDL cholesterol and apoA-I were lowest in Q(4) (P < 0.05 for both). Plasma LCAT activity was higher in Q(4) than in Q(1) (P < 0. 05) and PLTP activity was higher in Q(4) than in Q(2) (P < 0.05). Insulin sensitivity did not influence plasma CETP activity. Postheparin plasma lipoprotein lipase activity was highest and hepatic lipase activity was lowest in Q(1). Insulin infusion decreased PLTP activity (P < 0.05), irrespective of the degree of insulin sensitivity. The CETP genotype exerted no consistent effects on baseline plasma lipoproteins and LCAT, CETP, and PLTP activities. The decrease in plasma PLTP activity after insulin was larger in B1B1 than in B2B2 homozygotes (P < 0.05). These data suggest that insulin sensitivity influences plasma LCAT, PLTP, lipoprotein lipase, and hepatic lipase activities in men. As PLTP, LCAT, and hepatic lipase may enhance reverse cholesterol transport, it is tempting to speculate that high levels of these factors in association with insulin resistance could be involved in an antiatherogenic mechanism. A possible relationship between the CETP genotype and PLTP lowering by insulin warrants further study.     

Sclerostin concentrations in athletes: role of load and gender

Bone mass is the net product of formation and resorption, which are closely regulated by the equilibrium between endogenous/exogenous factors. Sclerostin inhibits the Wnt canonical signaling and is considered an anti-anabolic factor. We compared sclerostin serum concentrations between genders in athletes belonging to different sport disciplines, characterized by a different weight-bearing, and in their sedentary counterparts in order to study the possible link between bone metabolism in athletes and its peripheral concentration. We also compared sclerostin levels with bone alkaline phosphatase activity, a marker of bone formation. Sixty-one elite athletes, belonging to weight-bearing (15 male rugby players, 11 male enduro racers, 8 female basketball players), high-impact (6 male tennis players, 8 female ice skaters), non weight-bearing sports (13 male cyclists) and 16 sedentary controls were enrolled. Higher levels of sclerostin were found in females. Sclerostin was higher in weight-bearing than in non-weight-bearing disciplines in males. Significant inverse age-related correlation was found. Higher bone alkaline phosphatase activity was observed in females. The young adult elite athlete represents a peculiar physiologic model for studying sclerostin behavior: the applied load increased the marker concentrations, testifying a high bone turnover rate; however, a gender effect is evident.     

Effect of intralipid infusion on lecithin:cholesterol acyltransferase and lipoprotein lipase in young rats

We compared the effects of Intralipid and dextrose infusion on plasma lecithin:cholesterol acyltransferase (LCAT), plasma lipid profiles and lipolytic activity. We used 5-week-old male Sprague-Dawley rats which were given total parenteral nutrition (TPN) with either Intralipid (3 g/kg body weight) or an equicaloric amount of 25% dextrose in the presence or absence of heparin (1 or 10 IU/ml of TPN). 40 min after the end of 4 h of infusion, plasma LCAT activity was significantly decreased (P less than 0.001), while total cholesterol and free fatty acid levels were significantly (P less than 0.05) increased in rats given Intralipid as compared to those given dextrose. We found associations (P less than 0.005) between LCAT activity and total cholesterol and between LCAT and free fatty acid levels; the coefficients of negative correlation were 0.543 and 0.607, respectively. Concomitantly to the increment in plasma total cholesterol levels, there was a decrease in the high-density lipoprotein (HDL) cholesterol fraction; the latter, which was 40% of the total plasma cholesterol in control and dextrose-infused rats, declined to 9% in rats given Intralipid. Administration of heparin during Intralipid infusion, even up to 10 IU/ml of TPN, did not affect any of these changes. After dextrose infusion, the values of all three parameters were similar to those of the control group. Plasma lipolytic activity was not significantly different between rats given infusion (Intralipid or dextrose) and controls. However, in the presence of heparin, plasma lipolytic activity increased similarly in both infused groups. These data indicate that in young rats, Intralipid infusion leads to an increase in plasma total cholesterol and free fatty acid levels, which correlates with a decrease in LCAT activity; the concurrent decrease in HDL cholesterol levels might account, in part, for the loss of LCAT activity. The administration of heparin results in an elevation of plasma lipolytic activity; however, it does not prevent the hypercholesterolemia, nor the decline in LCAT activity associated with Intralipid infusion.     

Characterization and functional studies of lipoproteins, lipid transfer proteins, and lecithin:cholesterol acyltransferase in CSF of normal individuals and patients with Alzheimer's disease

We investigated the lipoprotein distribution and composition in cerebrospinal fluid (CSF) in a group of patients with Alzheimer's disease (AD) or affected by other types of dementia in comparison to non-demented controls. We found slightly decreased apolipoprotein (apo)E and cholesterol concentrations in CSF of AD patients and moderately increased apoA-I concentrations, while in patients suffering from other types of dementia the apoA-I CSF concentration was increased. ApoA-IV concentrations varied widely in human CSF, but were not associated with any clinical condition. HDL(2)-like apoE-containing lipoproteins represent the major lipoprotein fraction. In CSF of normal controls, only a minor HDL(3)-like apoA-I-containing lipoprotein fraction was observed; this fraction was more prevalent in AD patients. ApoA-II was recovered mostly in the HDL(3) density range, while apoA-IV was not associated with lipoproteins but appeared in a lipid-free form, co-localizing with LCAT immunoreactivity. Bi-dimensional analysis demonstrated pre-beta and alpha apoA-I-containing particles; apoE and apoA-II were detected only in alpha-migrating particles. ApoA-IV distributed both to pre-beta and gamma-migrating particles; the LCAT signal was co-localized in this gamma-migrating fraction. Enzymatically active LCAT was present in human CSF as well as PLTP activity and mass; no CETP mass was detected. In CSF from AD patients, LCAT activity was 50% lower than in CSF from normal controls. CSF lipoproteins induced a significant cholesterol efflux from cultured rat astrocytes, suggesting that they play an active role in maintaining the cholesterol homeostasis in brain cells.     

Erythropoietic adaptations to endurance training

Erythropoietic adaptations involving the oxygen dissociation curve (ODC) and erythropoietin production have been implicated in the etiology of reduced blood haemoglobin concentrations in sportspersons (known as sports anaemia). A significant increase in the half-saturation pressure indicating a right-shift in the ODC was measured in 34 male [25.8-27.4 mmHg (3.44-3.65 kPa)] and 16 female (25.8-27.7 mmHg (3.44-3.69 kPa)] trained distance runners (P less than 0.01 for both genders) after completing a standard 42-km marathon. Erythrocyte 2,3-diphosphoglycerate concentrations measured concurrently were unaltered by exercise, although consistently higher in the female compared to the male athletes (P less than 0.05). The serum erythropoietin (EPO) concentrations of 15 male triathletes (26.3 U.ml-1) were significantly lower than those of 45 male distance runners (31.6 U.ml-1; P less than 0.05). However, the mean serum EPO concentrations of male and female athletes engaged in a variety of sports were not different from those of sedentary control subjects of both sexes (26.5-35.3 U.ml-1). Furthermore, the serum EPO concentrations were unaltered after prolonged strenuous exercise in 20 male marathon runners. These data suggest that the haematological status of these endurance athletes is in fact normal and that the observed shift in the ODC, while providing a physiological advantage during exercise, has no measurable effect on the erythropoietic drive.     

不同球类运动对大学生上下肢骨密度及其方向性不对称的影响

为探究不同球类运动对上下肢骨密度及其方向性不对称的影响,特选取研究对象共210人,均分为7组,即篮球组、排球组、足球组、羽毛球组、乒乓球组、网球组和对照组,测量其上下肢的骨密度和方向性不对称性(DA)。结果显示,篮球组、排球组、羽毛球组、乒乓球组和网球组的上肢骨密度都是右侧明显高于左侧,下肢骨密度仅足球组表现为右侧高于左侧;不同组间的上下肢骨密度和DA具有统计学差异。结果还显示,左侧上肢骨密度的组间排序为排球组>足球组>第二亚组(乒乓球组、网球组和羽毛球组)>对照组,篮球组>乒乓球组、网球组和羽毛球组>对照组;右侧上肢骨密度的排序为网球组>乒乓球组、排球组和篮球组>足球组>对照组,乒乓球组>羽毛球组>足球组>对照组;左侧下肢骨密度的排序为足球组>篮球组、排球组、羽毛球组、乒乓球组和网球组>对照组;右侧下肢骨密度的排序为足球组>排球组、篮球组、网球组、羽毛球组和乒乓球组>对照组,排球组>羽毛球组和乒乓球组>对照组;DA的排序为网球组>乒乓球组、羽毛球组、篮球组和排球组,乒乓球组&g...