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At least 361 records · Page 20Linked to original sources

Functional deficits in athletes with a history of low back pain: a pilot study.

OBJECTIVE: To evaluate whether athletes with a history of low back pain (LBP) would, on average, perform slower on a timed 20-m shuttle run as compared with a normal athletic population. DESIGN: A timed shuttle run to evaluate residual functional limitations in college athletes with resolved LBP. SETTING: National College Athletic Association (NCAA) division I college. PARTICIPANTS: NCAA division I athletes (161 men, 50 women). INTERVENTION: A timed 20-m shuttle run. MAIN OUTCOME MEASURE: Each athlete was timed in a divided 20 m (66 ft) run in which 2 taped lines were positioned 6.7 m (22 ft) apart. RESULTS: Of 211 athletes evaluated, 27 had been treated for LBP during the previous year. Currently asymptomatic athletes with a recent history of LBP were slower (6.3s vs 5.8s) during performance of the timed 20-m shuttle run than athletes without LBP (P=.0002). CONCLUSIONS: Athletes with resolved LBP were slower than a matched group of normal athletes without LBP in the timed 20-m shuttle run. Further research is needed to support these findings and to understand fully the influence of the kinetic chain and the effects of both gender and sport on the observed findings.

Adult↗

Personality and mood of former elite male athletes--a descriptive study.

The purpose of this study was to describe the personality and mood of former athletes in middle and old age. The subjects were male athletes who represented Finland from 1920 to 1965 and male referents who were classified as healthy at 20 years of age. The athletes were classified into a total of five athlete groups (endurance, power/combat, power/individual, team, shooting) and one reference group. Four personality scales (extroversion, neuroticism, life satisfaction, and hostility) were used in a baseline questionnaire in 1985 (athletes N = 1040, referents N = 777). Anxiety and depression were assessed in a follow-up in 1995 (athletes N = 758, referents N = 578) with a shortened version of the BSI-53 symptom inventory. According to ANCOVA there were group differences in extroversion, neuroticism, and life satisfaction but not in hostility. Athletes who had participated in power/combat sports and team sports were more extroverted than referents. Endurance sport and shooting sport athletes had lower neuroticism scores than the referents. Endurance, power/combat, team and shooting sport athletes were more satisfied with their lives than were the referents. Discriminant analysis mainly supported these findings. Differences regarding depression were also statistically significant between the groups as referents were more depressed than endurance sport and team sport athletes. No group differences in anxiety were found. The subjects described in this study are unique in number of respects. Bearing in mind the limitations of the study subjects, it is concluded that former athletes differ from nonathletes in some personality characteristics and depression.

Adult↗

Left ventricular morphology and function in female athletes: a meta-analysis.

The purpose of the present study was to examine the impact of physical training upon cardiac structure and function, and identify physiologic upper limits in female athletes. Meta-analytical techniques were applied to 13 published echocardiographic studies examining cardiac structure and function in female athletes. The study group included 890 athletes and 333 controls. For comparison of sporting discipline, studies were partitioned into 3 categories (endurance, strength/sprint, team). Significant (p < 0.05) effect sizes were observed for all structural measures between athletes and controls. Significant effect size differences existed between sporting groups for LVIDd and LVM only, with endurance and team game athletes demonstrating the largest effect sizes compared to strength trained athletes. No significant effect of training was observed for left ventricular diastolic or systolic function, with the exception of stroke volume where a significant effect size difference was observed between athletes and controls with no observed difference between sporting groups. Maximum reported upper limits for LV wall thickness and LVIDd in female athletes were 12 mm and 66 mm respectively. Chronic exercise training results in cardiac enlargement in female athletes. The nature of physiologic adaptation is similar to that observed in male athletes. LV wall thickness values greater than 12 mm in female athletes should be viewed with caution and indicate a more comprehensive evaluation to establish a physiological or pathological basis for the observed left ventricular enlargement.

Adaptation, Physiological↗

Pulmonary O2 uptake on-kinetics in endurance- and sprint-trained master athletes.

The purpose of this study was to characterise the VO2 kinetic response to moderate intensity cycle exercise in endurance-trained (END) and sprint or power-trained (SPR) track and field master athletes ranging in age from 45 to 85 years. We hypothesised that the time constant (tau) describing the Phase II VO2 on-response would be smaller in the END compared to the SPR athletes, and that the tau would become greater with increasing age in both groups. Eighty-four master athletes who were competing at either the British or European Veteran Athletics Championships acted as subjects, and were classified as either END (800 m - marathon; n = 41), or SPR (100 - 400 m and field events; n = 43) specialists. Subjects completed two 6 minute "step" transitions to a work rate of moderate intensity on a cycle ergometer and pulmonary gas exchange was measured breath-by-breath. Analysis of variance revealed that SPR athletes had slower VO2 on-kinetics (i.e., greater tau) compared to END athletes at each of the age groups studied: 46 - 55 yrs (END: 25 +/- 6 vs. SPR: 36 +/- 9 s; p < 0.10), 56 - 65 yrs (END: 25 +/- 5 vs. SPR: 35 +/- 10 s; p < 0.05), 66 - 75 yrs (END: 29 +/- 10 vs. SPR: 40 +/- 13 s; p < 0.05), and 76 - 85 yrs (END: 31 +/- 10 vs. SPR: 51 +/- 18 s; p < 0.05). The VO2 on-kinetics became slower with advancing age in the SPR athletes (p < 0.05 between 56 - 65 and 76 - 85 yrs) but were not significantly changed in the END athletes. The slower VO2 on-kinetics in SPR compared to END master athletes is consistent both with differences in physiology (e.g., muscle fibre type, oxidative/glycolytic capacity) and training between these specialist athletes. Master END athletes have similar tau values to their younger counterparts (approximately 25 s) suggesting that participation in endurance exercise training limits the slowing of VO2 on-kinetics with age in this population.

Aged↗

Allergy and asthma in elite summer sport athletes.

Exercise may increase ventilation up to 200 L/min for short periods of time in speed and power athletes, and for longer periods in endurance athletes, such as long-distance runners and swimmers. Therefore highly trained athletes are repeatedly and strongly exposed to cold air during winter training and to many pollen allergens in spring and summer. Competitive swimmers inhale and microaspirate large amounts of air that floats above the water surface, which means exposure to chlorine derivatives from swimming pool disinfectants. In the summer Olympic Games, 4% to 15% of the athletes showed evidence of asthma or used antiasthmatic medication. Asthma is most commonly found in endurance events, such as cycling, swimming, or long-distance running. The risk of asthma is especially increased among competitive swimmers, of which 36% to 79% show bronchial hyperresponsiveness to methacholine or histamine. The risk of asthma is closely associated with atopy and its severity among athletes. A few studies have investigated occurrence of exercise-induced bronchospasm among highly trained athletes. The occurrences of exercise-induced bronchospasm vary from 3% to 35% and depend on testing environment, type of exercise used, and athlete population tested. Mild eosinophilic airway inflammation has been shown to affect elite swimmers and cross-country skiers. This eosinophilic inflammation correlates with clinical parameters (ie, exercise-induced bronchial symptoms and bronchial hyperresponsiveness). Athletes commonly use antiasthmatic medication to treat their exercise-induced bronchial symptoms. However, controlled studies on their long-term effects on bronchial hyperresponsiveness and airway inflammation in the athletes are lacking. Follow-up studies on asthma in athletes are also lacking. What will happen to bronchial hyperresponsiveness and airway inflammation after discontinuation of competitional career is unclear. In the future, follow-up studies on bronchial responsiveness and airway inflammation, as well as controlled studies on both short- and long-term effects of antiasthmatic drugs in the athletes are needed.

Asthma↗

Asthma in United States olympic athletes who participated in the 1998 olympic winter games.

BACKGROUND: About one of every 5 athletes who participated in the 1996 Summer Olympic Games in Atlanta had a past history of asthma, had symptoms that suggested asthma, or took asthma medications. No previous study has determined the prevalence of asthma in all US athletes who participated in an Olympic Winter Games. OBJECTIVES: We sought to determine how many US athletes who participated in the 1998 Olympic Winter Games had a past history of asthma, had symptoms that suggested asthma, or indicated taking a medication used to treat asthma. METHODS: We evaluated responses to questions that asked about allergic and respiratory diseases in the United States Olympic Committee Medical History Questionnaire that was completed by all 196 athletes who represented the United States at the 1998 Olympic Winter Games in Nagano, Japan. RESULTS: Forty-three (21.9%) of the 196 athletes had a previous diagnosis of asthma, and 36 (18. 4%) recorded use of an asthma medication at some time in the past. Forty-four (22.4%) reported use of an asthma medication, a diagnosis of asthma, or both (our basis for the diagnosis of asthma). Thirty-four (17.4%) of the athletes were currently taking an asthma medication at the time that they completed the questionnaire or indicated that they took these medications on a permanent or semipermanent basis and were considered to have active asthma. Athletes who participated in Nordic combined, cross-country, and short track events had the highest prevalence of having been told that they had asthma or had taken an asthma medication in the past (60.7%) in contrast with only one (2.8%) of the 36 athletes who participated in bobsled, biathlon, luge, and ski jumping. Eighteen (24%) of 75 athletes who participated in alpine, long track, figure skating, snow boarding, and curling had a previous diagnosis of asthma or recorded use of an asthma medication. CONCLUSIONS: We conclude that asthma appeared to have been more common in athletes who participated in the 1998 Winter Games than in athletes who participated in either the 1996 or 1984 Summer Games. Clearly, asthma rates vary widely among sports. This suggests that the environment in which exercise is performed is important in leading to a decrease in the amount of exercise required to trigger asthma and perhaps in causing injury to the airways.

Asthma↗

Evidence for an inadequate hyperventilation inducing arterial hypoxemia at submaximal exercise in all highly trained endurance athletes.

PURPOSE: The majority of highly trained endurance athletes with a maximal oxygen uptake greater than 60 mL x min(-1) x kg(-1) develop exercise-induced hypoxemia (EIH). Yet some of them apparently do not. The pathophysiology of EIH seems to be multifactorial, and one explanatory hypothesis is a relative hypoventilation. Nevertheless, conflicting results have been reported concerning its contribution to EIH. The aim of this study was to compare the cardiorespiratory responses to maximal exercise of highly trained endurance athletes demonstrating the same aerobic capacity without EIH (N athletes) and with EIH (H athletes). METHODS: Ten N athletes and twelve H athletes performed an incremental exercise test. Measurements of arterial blood gases and cardiorespiratory parameters were performed at rest and during exercise. RESULTS: All athletes presented a significant decrease in PaO2 (P < 0.05) from rest up to 80% VO2max associated with an increase in PaCO2, both findings consistent with a relative hypoventilation. Then the H athletes, who had a greater training volume per week and a higher second ventilatory threshold than the N athletes (respectively, 17 +/- 1.1 vs 13.1 +/- 0.7 h x wk(-1); 91.8 +/- 1.7 vs 86.1 +/- 1.8% VO2max), presented a continuous PaO2 decrease up to VO2max. This was associated with a widening (Ai-a)DO2. CONCLUSION: This study showed that a relative hypoventilation, probably induced by a high level of endurance training, induced hypoxemia in all athletes. However, a nonventilatory mechanism, perhaps related to the volume of training, seemed to affect gas exchanges beyond the second ventilatory threshold in the H athletes, thereby enhancing EIH.

Adult↗

Low back pain in college athletes. A prospective study correlating lower extremity overuse or acquired ligamentous laxity with low back pain.

STUDY DESIGN: A prospective evaluation of the incidence of low back pain in college athletes was undertaken. OBJECTIVES: To evaluate prospectively leg length discrepancy, hip flexor tightness, and lower extremity acquired laxity or overuse as predictive factors for low back pain in college athletes. SUMMARY OF BACKGROUND DATA: A pilot study found an association between low back pain and the factors to be studied. Several allusions to the kinetic chain theory appear in the literature, but little prospective research has been done in examining the effects of lower extremity involvement on the back. METHODS: Two-hundred fifty-seven college athletes representing nine varsity sports were screened during a preseason sports physical examination. Measures of flexibility, ligamentous stability, leg length discrepancy, and overuse syndromes were recorded. Athletes were observed throughout the ensuing year for low back pain requiring treatment by the athletic trainer. Those athletes with low back pain as the result of direct trauma to the region were excluded from the data. RESULTS: Twenty-four athletes (9.3%) received treatment for low back pain. Thirteen of 87 women (15%) compared with 11 of 170 men (6%) required treatment for low back pain (P = 0.048). Of 57 athletes with lower extremity acquired laxity or overuse, low back pain developed in 14 (P < 0.001). CONCLUSIONS: Athletes with lower extremity acquired ligamentous laxity or overuse may be at risk for the development of noncontact low back pain during athletic competition. Female athletes with lower extremity involvement appeared to have a higher incidence of low back pain treatment compared with their male counterparts. Inflexibility of the lower extremities or leg length discrepancy were not associated with future low back pain treatment.

Adult↗

Patellar tendon ultrasonography in asymptomatic active athletes reveals hypoechoic regions: a study of 320 tendons. Victorian Institute of Sport Tendon Study Group.

OBJECTIVE: To compare patellar tendon sonographic findings in active, currently asymptomatic, elite athletes with those in nonathletic controls. DESIGN: Cross-sectional cohort study with convenience control sample. SETTING: The Victorian Institute of Sport Tendon Study Group, an institutional elite athlete study group in Australia. PATIENTS AND PARTICIPANTS: Two hundred elite male and female athletes from the sports of basketball, cricket, netball, and Australian rules football. Forty athletes who had current symptoms of jumper's knee were excluded from analysis, leaving 320 subject tendons in athletes who were currently asymptomatic. Twenty-seven nonathletic individuals served as controls. MAIN OUTCOME MEASURE: Sonographic patellar tendon appearance. We measured the dimensions of subject tendons and noted the presence or absence of hypoechoic regions and tendon calcification. Dimensions of hypoechoic regions were measured, and approximate cross-sectional areas were calculated. Chi-squared analysis was used to test the prevalence of hypoechoic regions in subjects and controls and men and women. RESULTS: In currently asymptomatic subjects, hypoechoic regions were more prevalent in athlete tendons (22%) than in controls (4%), in male subject tendons (30%) than in female subjects (14%), and in basketball players (32%) than in other athletes (9%) (all p < 0.01). Bilateral tendon abnormalities were equally prevalent in men and women but more prevalent in basketball players (15%) than in other athletes (3%) (p < 0.05). Sonographic hypoechoic regions were present in 35 of 250 (14%) patellar tendons in athletes who had never had anterior knee pain. CONCLUSIONS: Patellar tendon sonographic hypoechoic areas were present in asymptomatic patellar tendons of a proportion of elite athletes but rarely present in controls. This has implications for clinicians managing athletes with anterior knee pain.

Adult↗

Creatine supplementation patterns and perceived effects in select division I collegiate athletes.

OBJECTIVE: To describe patterns of creatine use in select Division I collegiate athletes based on recommended dosages according to body weight. Further, to report the perceived effects noted with creatine supplementation. DESIGN: Anonymous open-ended self-report descriptive questionnaire. SETTING: National Collegiate Athletic Association Division I institution. PARTICIPANTS: Two-hundred and nineteen male and female collegiate athletes representing eight varsity sports. MAIN OUTCOME MEASURE(S): An open-ended questionnaire was administered to determine patterns of creatine use during the loading and maintenance phases of this nutritional supplement. In addition, perceived positive, negative, and no effects associated with creatine usage patterns were determined from athlete responses on this self-report measure. RESULTS: Considering this select group of collegiate athletes, highly variable patterns of creatine supplementation were noted for loading/maintenance phases based on recommended dosages/days and body weight. Of the 219 athletes surveyed, 90 (41%) reported using creatine, while creatine supplementation was more prevalent among men than women. Creatine users (80 athletes, 89%) reporting perceived positive effects were primarily at or below recommended dosages for the loading phase but above recommended dosages in the maintenance phase. Creatine users (34 athletes, 38%) reporting perceived negative effects were primarily at or below recommended dosages in the loading phase but noticeably above recommended dosages in the maintenance phase. Ironically, all creatine users who reported negative side effects also reported positive effects. Creatine users (10 athletes, 11%) reporting no effects were below recommended loading dosages but above recommended maintenance dosages. CONCLUSIONS: The perceived positive effects noted support current research (strength/weight gains), while the perceived negative effects (cramping/gastrointestinal distress) were consistent with anecdotal reports surrounding creatine supplementation. Apparently, collegiate athletes in this study are in need of education regarding the proper use of creatine supplementation. Additional studies are needed to ascertain creatine supplementation patterns of collegiate athletes in various settings.

Adolescent↗

Dysrhythmias and the athlete.

Young competitive athletes are perceived by the general population to be the healthiest members of society. The possibility that highly trained high school and college athletes may have a potentially serious cardiac condition that can predispose to life-threatening dysrhythmias or sudden cardiac death (SCD) seems paradoxical. The occurrence of SCD in young athletes from dysrhythmias is an uncommon but highly visible event. Media reports of sudden death in athletes have intensified the public and medical interest in medical, ethical, and legal issues related to cardiac disorders in the athlete. Developing screening strategies to identify conditions associated with sudden death has been the focus of attention of experts in the fields of arrhythmology and sports medicine and has resulted in Consensus Statements and Guidelines for evaluation of athletes. These guidelines provide information and recommendations for detection, evaluation, and management of athletes with cardiovascular disorders and criteria for eligibility and disqualification from participation in high-intensity and competitive sports. Differentiating normal exercise-induced physiologic changes in the heart from pathological conditions associated with sudden death is critical for developing screening strategies to identify athletes at high risk. This article discusses a case report of sudden cardiac death in an athlete followed by a brief review of various causes of cardiac dysrhythmias in young athletes and recommendations for screening and management of athletes with cardiovascular diseases.

Adolescent↗

The athlete's heart: remodeling, electrocardiogram and preparticipation screening.

Highly trained athletes show morphologic cardiac changes (ie, athlete's heart) that are the consequence of several determinants, including type of sport, gender, and, possibly, inherited genetic factors. The extent of physiologic cardiac remodeling may occasionally be substantial in highly trained athletes and may raise a differential diagnosis with structural cardiac disease, such as cardiomyopathies. In addition, athletes demonstrate a spectrum of alterations in the 12-lead electrocardiogram (ECG) pattern, including marked increase in precordial R-wave or S-wave voltages, ST segment or T-wave changes, and deep Q waves suggestive of left ventricular hypertrophy, that may raise the possibility of pathologic heart condition, but have also been viewed as a consequence of the cardiac morphologic remodeling induced by athletic conditioning. To evaluate the clinical significance of these abnormal ECGs, the authors compared ECG patterns to cardiac morphology and function (assessed by two-dimensional echocardiography in individual athlete) in a large population of 1005 elite athletes engaged in a variety of sporting disciplines. Forty percent of the athletes had abnormal ECGs, and a subgroup of about 15% showed distinctly abnormal and often bizarre patterns highly suggestive of cardiomyopathies, such as hypertrophic cardiomyopathy, in the absence of pathologic cardiac changes. Such alterations are likely the consequence of athletic conditioning itself and represent another potential component of athlete's heart syndrome. However, such false-positive ECGs represent a potential limitation to the efficacy of routine ECG testing in the preparticipation cardiovascular screening of large athletic populations.

Cardiomegaly↗

Cardiac arrest and sudden death in competitive athletes with arrhythmogenic right ventricular dysplasia.

Arrhythmogenic right ventricular dysplasia (ARVD) is a predisposing factor for sport-related cardiac arrest (CA), sudden cardiac death (SD), and life-threatening ventricular tachyarrhythmias (VT). The aim of this study was the assessment of athletes with ARVD, particularly the CA survivors. From 1974 to January 1996, 1642 competitive athletes (aver. 25.5 yr.), 136 of whom were top level athletes (TLA), were studied for important arrhythmic manifestations. All athletes underwent an individualised study protocol including a series of non invasive and invasive diagnostic techniques. One hundred and one athletes (90 males, 11 females, aver. 25.9 yr.) were diagnosed as being affected by ARVD on the basis of the WHO/ISFC criteria. The same percentage (about 6%) of ARVD is present in both the general arrhythmic athletes population and in the subgroup of TLA. Prevalence of ARVD among athletes with CA or SD is high (respectively 23% and 25%), confirming the observation that ARVD is one of the major causes of SD in Italian athletes. All CA were athletic activity related, indicating the potentiality of exercise as a cause of electrical destabilisation in subjects with ARVD. In athletes with documented ARVD intense sport activity has to be proscribed. In athletes at risk of CA or SD an aggressive treatment, ICD implantation and RF catheter ablation must be taken into consideration.

Adult↗

Vitamin/mineral supplement use among athletes: a review of the literature.

Vitamin/mineral supplements are often used by athletes as ergogenic aids to improve performance. This paper reviews studies of the prevalence, patterns, and explanations for vitamin/mineral supplement use among athletes. Fifty-one studies provided quantitative prevalence data on 10,274 male and female athletes at several levels of athletic participation in over 15 sports. The overall mean prevalence of athletes' supplement use was 46%. Most studies reported that over half of the athletes used supplements (range 6% to 100%), and the larger investigations found lower prevalence levels. Elite athletes used supplements more than college or high school athletes. Women used supplements more often than men. Varying patterns existed by sport. Athletes appear to use supplements more than the general population, and some take high doses that may lead to nutritional problems. Sport nutritionists should include a vitamin/mineral supplement history as part of their dietary assessment so they can educate athletes about vitamin/mineral supplements and athletic performance.

Administration, Oral↗

Role of exercise stress test in master athletes.

BACKGROUND: The effectiveness of cardiovascular screening in minimising the risk of athletic field deaths in master athletes is not known. OBJECTIVE: To evaluate the prevalence and clinical significance of ST segment depression during a stress test in asymptomatic apparently healthy elderly athletes. METHODS: A total of 113 male subjects aged over 60 were studied (79 trained and 34 sedentary); 88 of them (62 trained and 26 sedentary) were followed up for four years (mean 2.16 years for athletes, 1.26 years for sedentary subjects), with a resting 12 lead electrocardiogram (ECG), symptom limited exercise ECG on a cycle ergometer, echocardiography, and 24 hour ECG Holter monitoring. RESULTS: A significant ST segment depression at peak exercise was detected in one athlete at the first evaluation. A further case was seen during the follow up period in a previously "negative" athlete. Both were asymptomatic, and single photon emission tomography and/or stress echocardiography were negative for myocardial ischaemia. The athletes remained symptom-free during the period of the study. One athlete died during the follow up for coronary artery disease: he showed polymorphous ventricular tachycardia during both the exercise test and Holter monitoring, but no significant ST segment depression. CONCLUSIONS: The finding of false positive ST segment depression in elderly athletes, although still not fully understood, may be related to the physiological cardiac remodelling induced by regular training. Thus athletes with exercise induced ST segment depression, with no associated symptoms and/or complex ventricular arrhythmias, and no adverse findings at second level cardiological testing, should be considered free from coronary disease and safe to continue athletic training.

Age Factors↗

Screening elite winter athletes for exercise induced asthma: a comparison of three challenge methods.

BACKGROUND: The reported prevalence of exercise induced asthma (EIA) in elite winter athletes ranges from 9% to 50%. Many elite winter athletes do not report symptoms of EIA. At present there is no gold standard test for EIA. OBJECTIVE: To establish the efficacy of screening for EIA and examine the role of the eucapnic voluntary hyperventilation (EVH) challenge and laboratory based and sport specific exercise challenges in the evaluation of elite winter athletes. METHODS: 14 athletes (mean (SD) age 22.6 (5.7) years, height 177.2 (7.0) cm, body mass 68.9 (16.9) kg) from the Great Britain short-track speed skating (n = 10) and biathlon teams (n = 4) were studied. Each athlete completed a laboratory based and sport specific exercise challenge as well as an EVH challenge, in randomised order. RESULTS: All 14 athletes completed each challenge. Two had a previous history of asthma. Ten (including the two with a previous history) had a positive test to at least one of the challenges. Ten athletes had a positive response to EVH; of these, only three also had a positive response to the sport specific challenge. No athletes had a positive response to the laboratory based challenge. CONCLUSIONS: Elite athletes should be screened for EIA. EVH is a more sensitive challenge in asymptomatic athletes than sport specific and laboratory based challenges. If sporting governing bodies were to implement screening programmes to test athletes for EIA, EVH is the challenge of choice.

Adolescent↗

Electrocardiographic findings of repolarization in athletic students and control subjects.

We have investigated resting electrocardiograms in 1,299 athletic students and 151 sedentary control subjects. ST elevations were more frequent and pronounced in athletes compared to controls, whereas there was no difference in ST depressions. Athletes with ST elevation above 2 mm were characterized by lower heart rate, increased PQ duration, increased indices of left, right and septal hypertrophy and T wave amplitude. Negative T waves in 3 of 6 precordial leads, V3-6, were found in 1.5% of athletes and 0.7% of controls, and in V5-6 in 0.4% of athletes and none of controls, the differences not being significant. Athletes had significantly more often a T wave axis between +30 and -180 degrees and less often a frontal T wave axis between +30 and +180 degrees. The mean QRS-T angle was significantly greater in athletes, and U waves were more prominent. Analyzing athletes with QTc below and above 0.430 s, we found an increased heart rate, QRS duration, ST depression and a more pronounced left QRS axis in the group with QTc above 0.430 s. There was a positive correlation between QTc and heart rate which indicates that the use of Bazett's formula leads to an underestimation of QTc at lower heart rates and to an overestimation at higher heart rates. Bazett's formula does not provide an adequate correction for heart rate and should be used with caution. Our finding of a prolonged QTc in athletes compared to control subjects in spite of lower heart rate in the athletic group demonstrates that a real QTc prolongation exists in athletes.

Adult↗

Biomechanical measures of neuromuscular control and valgus loading of the knee predict anterior cruciate ligament injury risk in female athletes: a prospective study.

BACKGROUND: Female athletes participating in high-risk sports suffer anterior cruciate ligament injury at a 4- to 6-fold greater rate than do male athletes. HYPOTHESIS: Prescreened female athletes with subsequent anterior cruciate ligament injury will demonstrate decreased neuromuscular control and increased valgus joint loading, predicting anterior cruciate ligament injury risk. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: There were 205 female athletes in the high-risk sports of soccer, basketball, and volleyball prospectively measured for neuromuscular control using 3-dimensional kinematics (joint angles) and joint loads using kinetics (joint moments) during a jump-landing task. Analysis of variance as well as linear and logistic regression were used to isolate predictors of risk in athletes who subsequently ruptured the anterior cruciate ligament. RESULTS: Nine athletes had a confirmed anterior cruciate ligament rupture; these 9 had significantly different knee posture and loading compared to the 196 who did not have anterior cruciate ligament rupture. Knee abduction angle (P<.05) at landing was 8 degrees greater in anterior cruciate ligament-injured than in uninjured athletes. Anterior cruciate ligament-injured athletes had a 2.5 times greater knee abduction moment (P<.001) and 20% higher ground reaction force (P<.05), whereas stance time was 16% shorter; hence, increased motion, force, and moments occurred more quickly. Knee abduction moment predicted anterior cruciate ligament injury status with 73% specificity and 78% sensitivity; dynamic valgus measures showed a predictive r2 of 0.88. CONCLUSION: Knee motion and knee loading during a landing task are predictors of anterior cruciate ligament injury risk in female athletes. CLINICAL RELEVANCE: Female athletes with increased dynamic valgus and high abduction loads are at increased risk of anterior cruciate ligament injury. The methods developed may be used to monitor neuromuscular control of the knee joint and may help develop simpler measures of neuromuscular control that can be used to direct female athletes to more effective, targeted interventions.

Adolescent↗