Right and Left Ventricular Function and Mass in Male Elite Master Athletes: A Controlled Contrast-Enhanced Cardiovascular Magnetic Resonance Study.

BACKGROUND: It is under debate whether the cumulative effects of intensive endurance exercise induce chronic cardiac damage, mainly involving the right heart. The aim of this study was to examine the cardiac structure and function in long-term elite master endurance athletes with special focus on the right ventricle by contrast-enhanced cardiovascular magnetic resonance. METHODS AND RESULTS: Thirty-three healthy white competitive elite male master endurance athletes (age range, 30-60 years) with a training history of 29±8 years, and 33 white control subjects pair-matched for age, height, and weight underwent cardiopulmonary exercise testing, echocardiography including tissue-Doppler imaging and speckle tracking, and cardiovascular magnetic resonance. Indexed left ventricular mass and right ventricular mass (left ventricular mass/body surface area, 96±13 and 62±10 g/m(2); P<0.001; right ventricular mass/body surface area, 36±7 and 24±5 g/m(2); P<0.001) and indexed left ventricular end-diastolic volume and right ventricular end-diastolic volume (left ventricular end-diastolic volume/body surface area, 104±13 and 69±18 mL/m(2); P<0.001; right ventricular end-diastolic volume/body surface area, 110±22 and 66±16 mL/m(2); P<0.001) were significantly increased in athletes in comparison with control subjects. Right ventricular ejection fraction did not differ between athletes and control subjects (52±8 and 54±6%; P=0.26). Pathological late enhancement was detected in 1 athlete. No correlations were found for left ventricular and right ventricular volumes and ejection fraction with N-terminal pro-brain natriuretic peptide, and high-sensitive troponin was negative in all subjects. CONCLUSIONS: Based on our results, chronic right ventricular damage in elite endurance master athletes with lifelong high training volumes seems to be unlikely. Thus, the hypothesis of an exercise-induced arrhythmogenic right ventricular cardiomyopathy has to be questioned.

Validity of Lactate Thresholds in Inline Speed Skating.

Lactate thresholds are commonly used as estimates of the highest workload where lactate production and elimination are in equilibrium (maximum lactate steady state [MLSS]). However, because of the high static load on propulsive muscles, lactate kinetics in inline speed skating may differ significantly from other endurance exercise modes. Therefore, the discipline-specific validity of lactate thresholds has to be verified. Sixteen competitive inline-speed skaters (age: 30 ± 10 years; training per week: 10 ± 4 hours) completed an exhaustive stepwise incremental exercise test (start 24 km·h, step duration 3 minutes, increment 2 km·h) to determine individual anaerobic threshold (IAT) and the workload corresponding to a blood lactate concentration of 4 mmol·L (LT4) and 2-5 continuous load tests of (up to) 30 minutes to determine MLSS. The IAT and LT4 correlated significantly with MLSS, and the mean differences were almost negligible (MLSS 29.5 ± 2.5 km·h; IAT 29.2 ± 2.0 km·h; LT4 29.6 ± 2.3 km·h; p > 0.1 for all differences). However, the variability of differences was considerable resulting in 95% limits of agreement in the upper range of values known from other endurance disciplines (2.6 km·h [8.8%] for IAT and 3.1 km·h [10.3%] for LT4). Consequently, IAT and LT4 may be considered as valid estimates of the MLSS in inline speed skating, but verification by means of a constant load test should be considered in cases of doubt or when optimal accuracy is needed (e.g., in elite athletes or scientific studies).

Intensity control in swim training by means of the individual anaerobic threshold.

This study aimed at evaluating the homogeneity of physiological responses during swim training bouts with intensities prescribed by reference to the individual anaerobic threshold (IAT). Eighteen competitive front crawl swimmers (female 5, male 13, 10 long-distance, and 8 short-distance swimmers [LDSs, SDSs], age: 17 ± 1.7 years, training history: 7.0 ± 2.8 years, training volume per week: 35 ± 5.7 km) performed an incremental swimming test to determine the IAT. Within a maximum of 3 weeks, 4 training programs were conducted: 20 × 100-m low-intensity endurance training (EN(low), 97% IAT), 5 × 400-m high-intensity endurance training (EN(high), 101% IAT), 5 × 200 m (IT1, 105% IAT), and 10 × 100 m (IT2, 108% IAT) intensive interval training. Blood lactate concentrations (bLa) were determined during each training session. The results are given as median (25th and 75th percentiles). During EN(low) and EN(high), the mean bLas were 1.8 mmol·L(-1) (1.3/3.0 mmol·L(-1)) and 4.4 mmol·L(-1) (3.9/6.4 mmol·L(-1)). The bLas were higher during both IT programs: IT1, 6.3 mmol·L(-1) (5.6/7.2 mmol·L(-1)); IT2, 5.8 mmol·L(-1) (5.0/6.5 mmol·L(-1)). The bLas of most individuals were close to the median values (±2.4 mmol·L(-1)). However, in each of the training programs, some subjects showed bLa values that were clearly above (3-7 mmol·L(-1) higher). In particular, SDSs reached higher bLas at the same intensity compared with LDSs. It is concluded that intensity prescriptions by means of IAT seem to elicit an expected metabolic response in approximately 85% of swim training sessions. The observed average bLa is in the range of those recommended in the scientific literature.

Polymorphisms in the IGF1 signalling pathway including the myostatin gene are associated with left ventricular mass in male athletes.

BACKGROUND: Athlete's heart as an adaptation to long-time and intensive endurance training can vary considerably between individuals. Genetic polymorphisms in the cardiological relevant insulin-like growth factor 1 (IGF1) signalling pathway seem to have an essential influence on the extent of physiological hypertrophy. OBJECTIVE: Analysis of polymorphisms in the genes of IGF1, IGF1 receptor (IGF1R) and the negative regulator of the cardiac IGF1 signalling pathway, myostatin (MSTN), and their relation to left ventricular mass (LVM) of endurance athletes. METHODS: In 110 elite endurance athletes or athletes with a high amount of endurance training (75 males and 35 females) and 27 male controls, which were examined by echocardiographic imaging methods and ergometric exercise-testing, the genotypes of a cytosine-adenine repeat polymorphism in the promoter region of the IGF1 gene and a G/A substitution at position 3174 in the IGF1R gene were determined. Additionally, a mutation screen of the MSTN gene was performed. RESULTS: The polymorphisms in the IGF1 and the IGF1R gene showed a significant relation to the LVM for male (IGF1: p=0.003; IGF1R: p=0.01), but not for female athletes. The same applies to a previously unnoticed polymorphism in the 1 intron of the MSTN gene, whose deletion allele (AAA→AA) appears to increase the myostatic effect (p=0.015). Moreover, combinations of the polymorphisms showed significant synergistic effects on the LVM of the male athletes. CONCLUSIONS: The authors' results argue for the importance of polymorphisms in the IGF1 signalling pathway in combination with MSTN on the variant degree of physiological hypertrophy of male athletes.

Physical exercise prevents cellular senescence in circulating leukocytes and in the vessel wall.

BACKGROUND: The underlying molecular mechanisms of the vasculoprotective effects of physical exercise are incompletely understood. Telomere erosion is a central component of aging, and telomere-associated proteins regulate cellular senescence and survival. This study examines the effects of exercising on vascular telomere biology and endothelial apoptosis in mice and the effects of long-term endurance training on telomere biology in humans. METHODS AND RESULTS: C57/Bl6 mice were randomized to voluntary running or no running wheel conditions for 3 weeks. Exercise upregulated telomerase activity in the thoracic aorta and in circulating mononuclear cells compared with sedentary controls, increased vascular expression of telomere repeat-binding factor 2 and Ku70, and reduced the expression of vascular apoptosis regulators such as cell-cycle-checkpoint kinase 2, p16, and p53. Mice preconditioned by voluntary running exhibited a marked reduction in lipopolysaccharide-induced aortic endothelial apoptosis. Transgenic mouse studies showed that endothelial nitric oxide synthase and telomerase reverse transcriptase synergize to confer endothelial stress resistance after physical activity. To test the significance of these data in humans, telomere biology in circulating leukocytes of young and middle-aged track and field athletes was analyzed. Peripheral blood leukocytes isolated from endurance athletes showed increased telomerase activity, expression of telomere-stabilizing proteins, and downregulation of cell-cycle inhibitors compared with untrained individuals. Long-term endurance training was associated with reduced leukocyte telomere erosion compared with untrained controls. CONCLUSIONS: Physical activity regulates telomere-stabilizing proteins in mice and in humans and thereby protects from stress-induced vascular apoptosis.

Lactate threshold concepts: how valid are they?

During the last nearly 50 years, the blood lactate curve and lactate thresholds (LTs) have become important in the diagnosis of endurance performance. An intense and ongoing debate emerged, which was mainly based on terminology and/or the physiological background of LT concepts. The present review aims at evaluating LTs with regard to their validity in assessing endurance capacity. Additionally, LT concepts shall be integrated within the 'aerobic-anaerobic transition' - a framework which has often been used for performance diagnosis and intensity prescriptions in endurance sports. Usually, graded incremental exercise tests, eliciting an exponential rise in blood lactate concentrations (bLa), are used to arrive at lactate curves. A shift of such lactate curves indicates changes in endurance capacity. This very global approach, however, is hindered by several factors that may influence overall lactate levels. In addition, the exclusive use of the entire curve leads to some uncertainty as to the magnitude of endurance gains, which cannot be precisely estimated. This deficiency might be eliminated by the use of LTs. The aerobic-anaerobic transition may serve as a basis for individually assessing endurance performance as well as for prescribing intensities in endurance training. Additionally, several LT approaches may be integrated in this framework. This model consists of two typical breakpoints that are passed during incremental exercise: the intensity at which bLa begin to rise above baseline levels and the highest intensity at which lactate production and elimination are in equilibrium (maximal lactate steady state [MLSS]). Within this review, LTs are considered valid performance indicators when there are strong linear correlations with (simulated) endurance performance. In addition, a close relationship between LT and MLSS indicates validity regarding the prescription of training intensities. A total of 25 different LT concepts were located. All concepts were divided into three categories. Several authors use fixed bLa during incremental exercise to assess endurance performance (category 1). Other LT concepts aim at detecting the first rise in bLa above baseline levels (category 2). The third category consists of threshold concepts that aim at detecting either the MLSS or a rapid/distinct change in the inclination of the blood lactate curve (category 3). Thirty-two studies evaluated the relationship of LTs with performance in (partly simulated) endurance events. The overwhelming majority of those studies reported strong linear correlations, particularly for running events, suggesting a high percentage of common variance between LT and endurance performance. In addition, there is evidence that some LTs can estimate the MLSS. However, from a practical and statistical point of view it would be of interest to know the variability of individual differences between the respective threshold and the MLSS, which is rarely reported. Although there has been frequent and controversial debate on the LT phenomenon during the last three decades, many scientific studies have dealt with LT concepts, their value in assessing endurance performance or in prescribing exercise intensities in endurance training. The presented framework may help to clarify some aspects of the controversy and may give a rationale for performance diagnosis and training prescription in future research as well as in sports practice.

Precompetition cardiac assessment of football players participating in the 2006 FIFA World Cup Germany.

OBJECTIVES: To develop a precompetition medical assessment (PCMA) of elite football players aimed at identifying risk factors for sudden cardiac death. DESIGN: Retrospective analysis of the PCMA forms. PARTICIPANTS: Of the 32 national teams (with 23 players), PCMA forms from 605 players were submitted after the final match (82%). Data of 582 players were analyzed (79%). MAIN OUTCOME MEASURES: Recorded results of a standardized PCMA in all players before the 2006 FIFA World Cup including medical history, physical examination, resting/exercise electrocardiogram, and echocardiography were analyzed by 2 independent cardiologic reviewers. RESULTS: Apart from general deficits in data quality, at least 6 players (1.0%) could be identified as demanding further investigations to rule out a serious cardiovascular disease. CONCLUSIONS: Comprehensive cardiac testing is feasible in international elite football. To improve future results, the PCMA was revised. It is questionable if exercise stress testing should be included in future PCMA. To ensure correct results, sports cardiologic expertise is essential. In the face of organizational challenges and variable medical standards, alternative approaches to the practical implementation of the PCMA need to be investigated.

Bicarbonate infusion and pH clamp moderately reduce hyperventilation during ramp exercise in humans.

To test the hypothesis that the decrease in plasma pH contributes to the hyperventilation observed in humans in response to exercise at high workloads, five healthy male subjects performed a ramp exercise [maximal workload: 352 W (SD 35)] in a control situation and when arterialized plasma pH was maintained at the resting level (pH clamp) by intravenous infusion of sodium bicarbonate [129 mmol (SD 23), beginning at 59% maximal workload (SD 5)]. Bicarbonate infusion did not modify O(2) consumption (Vo(2)) but significantly (P < 0.05) increased arterial Pco(2), plasma bicarbonate concentration, and respiratory exchange ratio (P < 0.05). At the three highest workloads, pulmonary ventilation (Ve) and Ve/Vo(2) were approximately 5-10% lower (P < 0.05) when bicarbonate was infused than in the control situation, and hyperventilation was reduced by 15-30%. These data suggest that the decrease in plasma pH is one of the factors that contribute to the hyperventilation observed at high workloads.

Do inhaled beta(2)-agonists have an ergogenic potential in non-asthmatic competitive athletes?

The prevalence of asthma is higher in elite athletes than in the general population. The risk of developing asthmatic symptoms is the highest in endurance athletes and swimmers. Asthma seems particularly widespread in winter-sport athletes such as cross-country skiers. Asthmatic athletes commonly use inhaled beta(2)-agonists to prevent and treat asthmatic symptoms. However, beta(2)-agonists are prohibited according to the Prohibited List of the World Anti-Doping Agency. An exception can be made only for the substances formoterol, salbutamol, salmeterol and terbutaline by inhalation, as long as a therapeutic use exemption has been applied for and granted. In this context, the question arises of whether beta(2)-agonists have ergogenic benefits justifying the prohibition of these substances. In 17 of 19 randomised placebo-controlled trials in non-asthmatic competitive athletes, performance-enhancing effects of the inhaled beta(2)-agonists formoterol, salbutamol, salmeterol and terbutaline could not be proved. This is particularly true for endurance performance, anaerobic power and strength performance. In three of four studies, even supratherapeutic doses of salbutamol (800-1200 microg) had no ergogenic effect. In contrast to inhaled beta(2)-agonists, oral administration of salbutamol seems to be able to improve the muscle strength and the endurance performance. There appears to be no justification to prohibit inhaled beta(2)-agonists from the point of view of the ergogenic effects.

Cardiac tissue Doppler imaging in sports medicine.

The differentiation of training-induced cardiac adaptations from pathological conditions is a key issue in sports cardiology. As morphological features do not allow for a clear delineation of early stages of relevant pathologies, the echocardiographic evaluation of left ventricular function is the technique of first choice in this regard. Tissue Doppler imaging (TDI) is a relatively recent method for the assessment of cardiac function that provides direct, local measurements of myocardial velocities throughout the cardiac cycle. Although it has shown a superior sensitivity in the detection of ventricular dysfunction in clinical and experimental studies, its application in sports medicine is still rare. Besides technical factors, this may be due to a lack in consensus on the characteristics of ventricular function in relevant conditions. For more than two decades there has been an ongoing debate on the existence of a supernormal left ventricular function in athlete's heart. While results from traditional echocardiography are conflicting, TDI studies established an improved diastolic function in endurance-trained athletes with athlete's heart compared with controls.The influence of anabolic steroids on cardiac function also has been investigated by standard echocardiographic techniques with inconsistent results. The only TDI study dealing with this topic demonstrated a significantly impaired diastolic function in bodybuilders with long-term abuse of anabolic steroids compared with strength-trained athletes without abuse of anabolic steroids and controls, respectively.Hypertrophic cardiomyopathy is the most frequent cause of sudden death in young athletes. However, in its early stages, it is difficult to distinguish from athlete's heart. By means of TDI, ventricular dysfunction in hypertrophic cardiomyopathy can be disclosed even before the development of left ventricular hypertrophy. Also, a differentiation of left ventricular hypertrophy due to hypertrophic cardiomyopathy or systemic hypertension is possible by TDI. Besides the evaluation of different forms of left ventricular hypertrophy, the diagnosis of myocarditis is also of particular importance in athletes. Today, it still requires myocardial biopsy. The analysis of focal disturbances in myocardial velocities might be a promising non-invasive method; however, systematic validation studies are lacking. An important future issue for the implementation of TDI into routine examination will be the standardisation of procedures and the establishment of significant reference values for the above-mentioned conditions. Innovative TDI parameters also merit further investigation.

Effects of graded carbohydrate supplementation on the immune response in cycling.

PURPOSE: This study examined the acute immune response after three standardized cycling sessions of 4-h duration in the field with varying carbohydrate (CHO) supplementation in a randomized, double-blind, placebo-controlled fashion. We hypothesized that the ingestion of carbohydrate (6 or 12% CHO beverages; placebo (P) without CHO) during exercise attenuates the exercise-induced immune response in a dose-dependent manner. METHODS: A total of 14 male competitive cyclists and triathletes (age: 25 +/- 5 yr; height: 180 +/- 7 cm; weight: 72 +/- 9 kg; VO2max: 67 +/- 6 mL.min(-1).kg(-1)) cycled for 4 h on a 400-m track at a given workload of 70% of the individual anaerobic threshold (198 +/- 21 W). Leukocyte and lymphocyte subpopulations were measured by flow cytometry before, immediately, and 1 and 19 h after exercise. In addition, C-reactive protein (CRP) interleukin 6 (IL-6), and cortisol were determined. RESULTS: The exercise-induced increase in leukocytes, neutrophils, and monocytes was significantly attenuated to the same extent by 6 and 12% CHO (P < 0.001). No differences could be demonstrated for lymphocytes and natural killer cells. The increase in CRP was attenuated significantly by 12% CHO only (P < 0.05), whereas the increase in cortisol and IL-6 was significantly reduced by 6 and 12% CHO (P < 0.001). The postexercise neutrophilia, which dominated the exercise-induced leukocytosis, was strongly related to the postexercise concentration of cortisol (r = 0.72; P < 0.001). CONCLUSIONS: Because of the lacking dose-dependent difference, the ingestion of at least 6% CHO beverages can sufficiently attenuate the exercise-induced immune response and stress, especially in phagocytizing cells (neutrophils and monocytes) by the reduced release of cortisol.

Athlete's heart: right and left ventricular mass and function in male endurance athletes and untrained individuals determined by magnetic resonance imaging.

OBJECTIVES: Athlete's heart represents a structural and functional adaptation to regular endurance exercise. BACKGROUND: While left ventricular (LV) hypertrophy of the athlete's heart has been examined in many studies, the extent of right ventricular (RV) hypertrophy is still uncertain because of its complex shape and trabecular structure. To examine RV hypertrophy, we used magnetic resonance imaging (MRI) and hypothesized that athlete's heart is characterized by similar LV and RV hypertrophy. METHODS: The LV and RV mass, volume, and function in 21 male endurance athletes (A) (27 +/- 4 years; 70 +/- 8 kg; 178 +/- 7 cm; maximal oxygen uptake [VO(2)max]: 68 +/- 5 ml/min per kg) and 21 pair-matched untrained control subjects (C) (26 +/- 3 years; 71 +/- 9 kg; 178 +/- 6 cm; VO(2)max: 42 +/- 6 ml/min per kg) were analyzed by MRI (Magnetom Vision 1.5T, Siemens, Erlangen, Germany). RESULTS: Left ventricular masses: (A: 200 +/- 20 g; C: 148 +/- 17 g) and RV masses (A: 77 +/- 10 g; C: 56 +/- 8 g) differed significantly between the groups (p < 0.001). The LV and RV end-diastolic volumes (EDV) (LV-EDV 167 +/- 28 ml [A]; 125 +/- 16 ml [C]; RV-EDV 160 +/- 26 ml [A]; 128 +/- 10 ml [C]), and stroke volumes (SV) (LV-SV: 99 +/- 18 ml [A], 74 +/- 11 ml [C]; RV-SV: 102 +/- 18 ml [A], 79 +/- 8 ml [C]) were significantly different between the athletes and control subjects (p < 0.001), whereas ejection fractions (EF) (LV-EF: 59 +/- 3% [A]; 59 +/- 6% [C]; RV-EF: 63 +/- 3% [A], 62 +/- 3% [C]) and LV-to-RV ratios were similar for both groups (LV-to-RV mass: 2.6 +/- 0.2 [A], 2.6 +/- 0.3 [C]; LV-to-RV EDV: 1.05 +/- 0.14 [A], 0.99 +/- 0.14 [C]; LV-to-RV SV: 0.98 +/- 0.17 [A], 0.95 +/- 0.17 [C]; LV-to-RV EF: 0.93 +/- 0.07 [A], 0.96 +/- 0.10 [C]). CONCLUSIONS: Regular and extensive endurance training results in similar changes in LV and RV mass, volume, and function in endurance athletes. This leads to the conclusion that the athlete's heart is a balanced enlarged heart.

Independent elevations of N-terminal pro-brain natriuretic peptide and cardiac troponins in endurance athletes after prolonged strenuous exercise.

BACKGROUND: Although elevated resting brain natriuretic peptide (BNP) concentrations reflect heart disease, the meaning of exercise-induced increases is poorly understood and has been examined in small groups only. Therefore, the present study aimed to examine the increase in N-terminal pro-brain natriuretic peptide (NT-proBNP) and relations to cardiac troponin I and T (cTnI, cTnT) elevations after prolonged strenuous exercise in a large cohort of athletes. METHODS: We examined exercise-induced changes in NT-proBNP, cTnI, and cTnT in 105 obviously healthy endurance athletes (40 +/- 8 years) before and after prolonged strenuous exercise. Blood samples were taken before, 15 minutes, and 3 hours after a marathon (n = 46), a 100-km run (n = 14), and a mountain bike marathon (n = 45). RESULTS: Eighty-one of 105 athletes exceeded the upper reference limit of NT-proBNP (males/females 88:153 ng/L) after exercise. NT-proBNP increased in all 3 events (P < .001) with the highest increase in the 100-km runners (median increase 200 ng/L; 25th/75th percentile 115/770 ng/L), which differed from the increase in the marathon (97 ng/L; 36/254 ng/L) or the mountain bike marathon (78 ng/L; 37/196 ng/L) (P < .01). Cardiac troponin I exceeded 0.04 microg/L in 74%; cTnT exceeded 0.01 microg/L in 47% of athletes after exercise. NT-proBNP was not related to exercise-induced increases in cTnI or cTnT, but correlated with exercise time (r = 0.55, P < .001). CONCLUSIONS: Increases in NT-proBNP can be found in a major part of obviously healthy athletes after prolonged strenuous exercise. The release of BNP during and after exercise may not result from myocardial damage but may have cytoprotective and growth-regulating effects. The different nature of exercise-induced increases in BNP and cardiac troponins has to be elucidated in the future.

An alternative approach for exercise prescription and efficacy testing in patients with chronic heart failure: a randomized controlled training study.

BACKGROUND: Prescription of endurance training and documentation of its efficacy in patients with chronic heart failure (CHF) is usually done with reference to maximal ergometric measurements which are subject to form on the day changes and motivational influences. However, the use of submaximal parameters might represent an alternative approach. METHODS: This was tested in 54 patients with CHF (57 +/- 10 years, NYHA II: n = 40; NYHA III: n = 14) who were randomized into training (T; n = 26) or control group (CO; n = 28). Training consisted of 45 minutes cycling at an intensity corresponding to the anaerobic threshold (AT) and was conducted for 12 weeks, 4 to 5 times per week. Cardiorespiratory exercise testing was done before and after the experimental phase. Changes in well-being were investigated using a 5-point Likert scale. RESULTS: A significant rightward shift in the heart rate curve was demonstrated in T compared with CO (P = .01; T: decrease in resting heart rate by 8 per minute, during exercise by 7 to 11/min; CO: -1 and -1 to -3 per minute, respectively). Anaerobic threshold increased significantly by 11.6% in T (+0.11 +/- 0.11 L min(-1) oxygen uptake) compared with CO (-0.02 +/- 0.10 L min(-1)). Positive changes in well-being were significantly larger in T (P < .01). CONCLUSIONS: In patients with CHF, training can be prescribed and its efficacy can be evaluated by the exclusive use of submaximal parameters. Anaerobic threshold represents an appropriate training intensity in this population.

Running 8000 m fast or slow: Are there differences in energy cost and fat metabolism?

PURPOSE: To compare energy requirements and substrate use for running a given distance fast versus slow under field conditions. METHODS: Ten males and four females who were moderately endurance trained (32 +/- 6 yr; 71 +/- 11 kg; body mass index: 22.7 +/- 2.3 kg x m(-2); VO2max: 62.0 +/- 6.0 mL x min(-1) x kg(-1); individual anaerobic threshold [IAT]: 13.7 +/- 1.4 km x h(-1)) performed an incremental running protocol to determine IAT. Subsequently, two 8000-m runs at 70 and 95% IAT were performed on separate days in randomized order on an indoor track. Energy expenditure (EE) was measured by means of a portable metabolic device (indirect calorimetry). A meaningful difference in EE was defined as >10%. RESULTS: EE was significantly greater during the 95% IAT run than during the 70% IAT run (2650 +/- 276 and 2554 +/- 348 kJ, respectively). However, this difference was only 3.8 +/- 4.8%. Including measurements up to 10 min postexercise, the difference rose to 5.1 +/- 4.7% (95% IAT: 2830 +/- 301 kJ; 70% IAT: 2692 +/- 368 kJ). There was no significant difference between the absolute amounts of fat oxidized during the runs (70% IAT: 26 +/- 5 g; 95% IAT: 20 +/- 5 g). During the 95% IAT run, significantly more carbohydrates were metabolized than during the 70% IAT run (108 +/- 14 and 90 +/- 5 g, respectively). The difference in EE between the two runs increased from the first to the third part of the running distance (first: no significance; second: P < 0.01; third: P < 0.001). CONCLUSION: Energy requirements for a commonly run distance in recreational endurance training differ significantly but not relevantly between slow and fast speeds. However, increasing total running distance might lead to larger differences.

Injuries in female soccer players: a prospective study in the German national league.

BACKGROUND: In contrast to the high number of studies about soccer injuries in men, epidemiologic data in high-level female soccer players are scarce. PURPOSE: Analysis of injury incidence in elite female soccer players. STUDY DESIGN: Descriptive epidemiology study. METHODS: There were 165 female soccer players (age, 22.4 +/- 5.0 years) from 9 teams competing in the German national league, who were followed for one complete outdoor season. Their trainers documented the exposure to soccer on a weekly basis for each player, and the team physical therapists reported all injuries with regard to location, type, and circumstances of occurrence. An injury was defined as any physical complaint associated with soccer that limited sports participation for at least 1 day. RESULTS: There were 241 injuries sustained by 115 players (70%) reported; 39 injuries (16%) were owing to overuse, and 202 injuries (84%) were traumatic. Overall, 42% of the traumatic injuries occurred during training (2.8/1000 hours of training; 95% confidence interval, 2.2-3.4) and 58% during matches (23.3/1000 match hours; 95% confidence interval, 19.1-27.5); 102 of the traumatic injuries were caused by a contact situation, whereas 95 occurred without any contact. Most injuries (80%) were located at the lower extremities, concerning mainly the thigh (n = 44), knee (n = 45), and ankle (n = 43). Ankle sprain (n = 37) was the most often diagnosed injury. There were 51% minor injuries, 36% moderate injuries, and 13% major injuries. Eleven anterior cruciate ligament ruptures were observed during the season. CONCLUSION: The results revealed a high injury incidence rate in games as well as a comparably low incidence rate during training. An important finding of this investigation was the frequent occurrence of anterior cruciate ligament ruptures. Preventive measures should thus focus on the high prevalence of anterior cruciate ligament tears, mostly occurring in noncontact situations.