Injuries in professional male football players in Kosovo: a descriptive epidemiological study.

BACKGROUND: The incidence and severity of football-related injuries has been found to differ strongly between professional leagues from different countries. The aims of this study were to record the incidence, type and severity of injuries in Kosovarian football players and investigate the relationship between injury incidence rates (IRs), players' age and playing positions. METHODS: Players' age, anthropometric characteristics and playing positions, training and match exposure as well as injury occurrences were monitored in 11 teams (143 players) of Kosovo's top division during the 2013/14 season. The exact type, severity and duration of football-related injuries were documented following International Federation of Football Associations (FIFA) recommendations. RESULTS: A total of 272 injuries were observed, with traumatic injuries accounting for 71 %. The overall injury IR was 7.38 (CI: 7.14, 7.63) injuries per 1,000 exposure hours and ~11x lower during training as opposed to matches. Strains and ruptures of thigh muscles, ligamentous injuries of the knee as well as meniscus or other cartilage tears represented the most frequent differential diagnoses. While no statistical differences were found between players engaged in different playing positions, injury IR was found to be higher by 10-13 % in younger (IR = 7.63; CI: 7.39, 7.87) as compared to middle-aged (IR = 6.95; CI: 6.41, 7.54) and older players (IR = 6.76; CI: 5.71, 8.00). CONCLUSIONS: The total injury IR in elite football in Kosovo is slightly lower than the international average, which may be related to lesser match exposure. Typical injury patterns agree well with previously reported data. Our finding that injury IR was greater in younger players is related to a higher rate of traumatic injuries and may indicate a more aggressive and risky style of play in this age group.

Critical Power in Laboratory and Field Conditions Using Single-visit Maximal Effort Trials.

To compare critical power (CP) and the maximum work performed above CP (W') obtained from a single-visit laboratory test with a single-visit field test, 10 trained cyclists (V˙O(2max) 63.2±5.5 mL·min(-1)·kg(-1)) performed a laboratory and a field test. The laboratory test consisted of 3 trials to exhaustion between 2-15 min and the field test comprised 3 maximal efforts of 2, 6 and 12 min, where power output was measured using a mobile power meter. CP and W' were estimated using 3 mathematical models (hyperbolic, linear work-time, linear power -1/time). The agreement between laboratory and field conditions was assessed with the 95% limits of agreement (LoA). CP was not significantly different between laboratory (280±33 W) and field conditions (281±28 W) (P=0.950). W' was significantly higher in laboratory (21.6±7.1 kJ) compared to field conditions (16.3±7.4 kJ) (P=0.013). The bias was -2.8±27 W (95% LoA: -55 to 50 W) and 6.4±5.1 kJ (95% LoA: -3.5 to 16.4 kJ) for CP and W', respectively. No differences between the mathematical models were found for CP and W' (P=0.054-1.000). Although CP was not significantly different between conditions, a high random variation does not support its interchangeable use. The mathematical model used has no influence on estimates of CP and W'.

Therapeutic use of growth factors in the musculoskeletal system in sports-related injuries.

Growth factors (GFs) act as signalling agents for cells and become a more and more popular mean to influence the human body and its tissues. This review gives an overview of the current possibilities to use such agents in the field of sports related injuries and thus providing the athlete with a whole new potential to minimize recovery time. GFs and its application have been studied intensively for a long time starting with animal studies. For some of this GFs this research has been brought onto the next level to clinical phase trials. Agents such as insulin like growth factor 1 (IGF-1), mechano growth factor (MGF), basic fibroblast growth factor (B-FGF), platelet derived growth factor (PDGF), vascular endothelial growth factor (VEGF), transforming growth factor b (TGF-b), bone morphogenetic protein (BMP) and leukemia inhibitory factor (LIF) are being discussed in this review. These GFs not only have the potential to be used to cure injuries but also are being in the centre of interest for doping abusers and are a powerful yet not fully understood technique to gain performance.

Physical and physiological demands and hormonal responses in basketball small-sided games with different tactical tasks and training regimes.

OBJECTIVES: To evaluate external and internal training load (TL) and hormonal responses in basketball 3-versus-3 small-sided games (SSGs). DESIGN: Randomized repeated-measures study. METHODS: Twelve male basketball players participated to four 3-versus-3 SSGs characterized by different tactical tasks (offensive; defensive) and training regimes (long-intermittent: three 4-min bouts with 2' rest in between; short-intermittent: six 2-min bouts with 1' rest in between). Variables measured were: PlayerLoad (PL); percentage of maximal heart rate (%HRmax); Edwards' TL. Before and after the SSGs, saliva samples were collected to measure cortisol (C) and testosterone (T). Two-way (task; regime) repeated-measures ANOVA was performed for PL and %HRmax; C concentrations were analysed with a three-way (task; regime; time: pre/post) repeated-measures ANOVA; non-parametric analyses were performed for Edwards' TL and T. RESULTS: PL was moderately higher in offensive task (148.0±16.8 AU) compared to defensive (137.1±15.5 AU), and short regime (147.0±18.2 AU) compared to long (137.9±14.6 AU). %HRmax was moderately higher in offensive task (91.1±4.1%) compared to defensive: (88.7±5.4%), while it did not differ between regimes (long: 90.0±5.6%) (short: 89.8±4.2%); additionally, an interaction (task*regime) effect was found (ES: strong). Edwards' TL was moderately higher in offense-long SSG (56.6+2.4 AU) compared to defense-short (52.4+4.4 AU). C increased after the SSGs (ES: strong). T decreased after offense-short (ES: moderate) and increased after defense-long (ES: moderate) SSGs. CONCLUSIONS: Tactical tasks and training regimes influence external and internal demands of basketball SSGs. Steroid hormones respond in SSGs.

The heart rate turn point reliability and methodological aspects.

PURPOSE: The aim of the study was to test protocol variations on the heart rate performance curve (HRPC) and the heart rate turn point (HRTP) according to Conconi et al. (1996). Respiratory gas exchange variables were used to define three phases of energy supply (I, II, III). METHODS: Eighteen healthy young male subjects performed 4 tests (T1-T4). T1: initial speed of 6 km x h(-1) followed by increments of 0.6 km x h(-1) every 60 s. Subjects were than randomized for the next three tests. T2: initial speed 5.6 km x h(-1) followed by increments of 0.2 km x h(-1) every 20 s; T3: similar to T2, in the second half of phase III acceleration (S) was increased. T4: like T2, at the beginning of phase III, S was increased. No differences were found in the degree of the deflection of the HRPC expressed as factor kHR between T1 (0.228 +/- 0.225) and T2 (0.248 +/- 0.231) but a significant increase was found in T3 (0.533 +/- 0.248) and T4 (0.770 +/- 0.258). RESULTS: The modifications of the protocol (T3 and T4) systematically influenced the deflection of the HRPC, but kHR was highly reproducible in all tests. Eleven subjects showed degrees of deflection in the HRPC in all tests. There were no significant differences for S, HR, and VO2 at the HRTP. An HRTP was not found in seven subjects in neither T1 or T2; however, in T3 and T4, these seven subjects showed a deflection of HRPC resulting from the protocol. The HRTP was found to be dependent on the start of the acceleration in phase III. In cases with a linear time course in the HRPC in T1 and T2, in T3 an HRTP was found at 15.6 km x h(-1) and in T4 at 13.6 km x h(-1) , respectively. CONCLUSION: The Conconi test protocol with an accelerated increase in S in the final phase of the test has a major influence on the occurrence of the HRTP in cases of near linear HRPC.

Change in left atrial and ventricular dimensions during and immediately after exercise.

PURPOSE: The aim of this study was to evaluate differences in the left atrial (LAD), total ventricular end-diastolic (TEDD), end-systolic diameters (TESD), and left ventricular shortening fraction (SF) compared with heart rate (HR) and systolic blood pressure (SBP) during exercise and recovery. METHODS: Healthy young male (N = 15) and female (N = 16) subjects performed an incremental cycle ergometer test in upright position, and three phases of energy supply were defined by means of blood lactate concentration (LA) and respiratory gas exchange variables (I: aerobic; II: aerobic-anaerobic transition; III: anaerobic). Subjects were required to rest their arms on a steering bar and to lean their upper body forward; two dimensional (2-D) echocardiograms were obtained over the left parasternal area at rest (R), at the end of each phase, immediately within 15 s post, and 6 min after exercise (6 min). By using VINGMED's "Anatomical M-Mode," it was possible to extract M-Mode Sweeps from stored 2-D-Loops and perform the M-Mode measurement. RESULTS: In contrast to the significant decrease in TEDD and TESD from III to 15 s up to resting values and the significant increase in SF from III to 15 s, the moderate decrease in HR immediately post exercise (15 s) was not significant. The SBP showed a significantly decrease from III to 15 s; in contrast to TEDD, TESD, and SF, the values at 15 s were comparable with the values at II. For LAD, significant increase during exercise and a decrease during recovery were observed. Sex-specific differences of changes in measured variables could not be found. CONCLUSION: We concluded that post exercise measurement of left ventricular and atrial dimensions or SF were not valid to describe heart function at maximal exercise although immediately post exercise HR was near maximal level.

A physiological profile of tennis match play.

PURPOSE: The aim of this investigation was to examine physiological demands of single match play in tennis. METHODS: 20 players performed 10 matches of 50 min. Respiratory gas exchange measures (RGEM) and heart rates (HR) were measured using two portable systems. Lactate concentration was determined after each game. The average oxygen uptake (VO2) of 270 games was 29.1 +/- 5.6 mL.kg-1.min-1 (51.1 +/- 10.9% of VO2max). Average VO2 for a game ranged from 10.4 to 47.8 mL.kg-1.min-1 (20.4 and 86.8% of VO2max). Average lactate concentration (LA) was 2.07 +/- 0.9 mmol.L-1 (ranging from 0.7 to 5.2 mmol.L-1). Furthermore, we monitored the duration of rallies (DR), the effective playing time (EPT), and the stroke frequency (SF). The average values of 270 games were DR: 6.4 +/- 4.1 s, EPT: 29.3 +/- 12.1%, SF: 42.6 +/- 9.6 shots.min-1. RESULTS: Multiple regression revealed that the DR was the most promising variable for the determination of VO2 in match play (r = 0.54). The body surface area (BSA) and EPT were also entered into the calculation model. In games of two defensive players, VO2 was significantly higher than in games with at least one offensive player. CONCLUSION: Our results suggest that energy demands of tennis matches are significantly influenced by DR. The highest average VO2 of a game of 47.8 mL.kg-1.min-1 may be regarded as a guide to assess endurance capacity required to sustain high-intensity periods of tennis matches compared with average VO2 of 29.1 mL.kg-1.min-1 for the 270 games. Our results suggest that proper conditioning is advisable especially for players who prefer to play from the baseline.

Performance characteristics according to playing position in elite soccer.

The paper provides a large-scale study into the motion characteristics of top class soccer players, during match play, according to playing position. Three hundred top-class outfield soccer players were monitored during 20 Spanish Premier League and 10 Champions League games using a computerized match analysis system (Amisco Pro, Nice, France). Total distance covered in five selected categories of intensity, and the mean percentage of playing time spent in each activity were analyzed according to playing position. Midfield players covered a significantly greater total distance (p < 0.0001) than the groups of defenders and forwards did. Analyzing the different work rates showed significant differences (p < 0.5 - 0.0001) between the different playing positions. There were no significant differences between halves in the total distance covered, or in distances covered at submaximal and maximal intensities. However, significantly more distance was covered in the first half compared to the second in medium intensities (11.1 - 19 km/h). The current findings provide a detailed description of the demands placed on elite soccer players, according to their positional role at different work intensities, which may be helpful in the development of individualized training programs.

Responses of N-terminal pro-brain natriuretic peptide (NT-proBNP) and cardiac troponin I (cTnI) to competitive endurance exercise in recreational athletes.

The present study was designed to investigate whether the stress of a half-marathon race can induce myocardial cell injury or left ventricular dysfunction in moderately trained runners of both gender, as assessed by post-race plasma concentrations of biochemical cardiac-specific markers and by quantitative echocardiographic measurements. We examined 12 male (mean+/-SD); age: 42.8+/-7.3 yr; height: 177.6+/-7.4 cm; body mass: 75.6+/-9.4 kg; BMI: 24.1+/-1.8 and 13 female (mean+/-SD); age: 39.0+/-6.5 yr; height: 164.6+/-6.2 cm; body mass: 58.4+/-9.8 kg; BMI: 21.5+/-3.4 recreational runners, who completed a half-marathon race. Blood samples were collected from each subject before the half-marathon race as well as 20 min and 2 h post-race and cardiac troponin I (cTnI) and N-terminal pro-brain natriuretic peptide (NT-proBNP) were measured. Quantitative echocardiographic analyses of wall dimensions and ejection fraction were also obtained from 14 of 25 subjects within 1 wk after the race. Both blood markers showed significant changes (p<0.05-0.001) over the time course of the three blood draws. A significant percentage of laboratory analytes analyzed in this study were outside the reference ranges and fulfilled conventional criteria for cardiac muscle damage. However, echocardiography within one week following the competition did not show any evidence that running a half-marathon competition damages the myocardium. Strenuous endurance exercise in middle-aged recreational runners induces a significant elevation of biochemical cardiac-specific markers, which may reflect transient subclinical myocardial damage, but can also reflect a physiological reparative or adaptive process.

The constant velocity translatoric dynamo ergometer. A new approach to investigate neuromuscular, metabolic, and cardiovascular parameters.

The goal of this study was to investigate with the new dynamo ergometer the forces produced within a defined range of motion at a constant velocity during concentric translatoric work as well as to investigate fatigue based on neuromuscular and metabolic parameters. We examined 11 male sports students with the "Motomir" device with the subjects in a sitting position. The test consisted of four times 1 min of concentric leg work with 1-min rest phases in between. The subjects were asked to do maximum effort push movements with one leg and maximum effort pull movements with the other leg. The translatoric form of movement did not reveal any significant differences in strength between the left and right legs. The strength of the extensors was significantly higher than that of the flexors during all exercise stages (p < 0.001). A significant decrease in strength was established for extensor muscles and no significant decrease for the flexor muscles. The quotient of flexor/extensor was 0.43 +/- 0.07 in the first exercise stage and increased in every stage till the fourth. There was a correlation (p < 0.001) between the difference in lactate of the first and fourth exercise stages and the percentage of force decrease from the 1st to the 4th min. The electric activity of the vastus medialis, vastus lateralis, and gastrocnemius muscles decreased from the first to the fourth exercise stage. This decrease was however not significant. The translatoric constant velocity dynamo ergometer allows both diagnosis and training at varying angles and varying speeds while avoiding unphysiological maximum loads.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of laboratory and "on-court" endurance testing in tennis.

Treadmill testing (TT) commonly used in endurance testing is often not sport-specific. Therefore a field test (FT) for tennis players was developed. The purpose was 1) to compare metabolic and cardiorespiratory response between TT and FT and 2) to assess tennis stroke ratings during FT. In both tests ventilatory variables (VO2, VE, VT, Bf, VE x VO2(-1)), heart rate (HR), and lactate (LA) were measured. For both tests an "individual anaerobic threshold" (IAT) was calculated. The comparison of TT and FT yielded significant differences in cardiorespiratory and metabolic response. LA and VE were significantly higher in TT compared to FT at VO2 of 35, 40, and 45 ml x kg(-1) x min(-1). There were statistical differences between IAT resulting from both tests (TT vs. FT): HR (165+/-16, 175+/-11, p<0.001), VO2 (44.4+/-4.3, 47.8+/-4.8, p<0.05), LA (3.1+/-0.5, 2.5+/-0.4, p < 0.001), VE (97.0+/-15.6, 89.1+/-14.9, p < 0.05), VT (2.66+/-0.34, 2.34+/-0.47, p<0.05), VE/VO2 (27.9+/-3.9, 23.9+/-2.9, p<0.01). High correlation was found between stroke ratings and the national ranking of the players. We concluded that 1) metabolic, ventilatory, and cardiorespiratory demands of TT vs. FT were (semi)sport-specific and significantly different and 2) that the stroke rating in our study was a good predictor for tournament performance (r = 0.94). This type of stroke rating can be implemented in a FT.

[Amount and intensity of physical exercise in primary prevention]. / Umfänge und Intensität körperlicher Aktivität in der Primärprävention.

Numerous epidemiological studies have demonstrated an inverse relation between physical activity and physical "fitness" on one hand and premature death and the risk of chronic disease on the other hand. However, most of these studies showed crucial methodological and statistical differences, a fact which caused a lack of consensus of dose and intensity of physical activities for "health benefits". The optimal amount of physical activity to decrease mortality is in literature stated to range between 1,000 and 3,500 motoric kcal per week. Only a few data exist concerning the optimal intensity of preventive physical activities. There is some indication that only "vigorous" but not "non-vigorous" physical activities are associated with decreased mortality. Previous investigations suggest that a "threshold-intensity" (e.g. of at least 6 MET of "conditioning physical activity") is needed to produce an adequate preventive effect. On the other hand it has been documented, that "physical fitness" (endurance capacity) is a decisive factor for a decreased mortality. Therefore it may be assumed, that physical activities are only efficient for health benefits, if they also result in increased physical fitness. Following from this assumption the quality and quantity of training in primary prevention has to be adjusted to the individual requirements (performance, age, gender, health) of men.

Measurement of maximal power output in isokinetic and non-isokinetic cycling. A comparison of two methods.

The main goal of the study was to compare maximal power output and power output at different pedalling frequencies obtained during isokinetic all-out tests with maximal power output obtained during a single all-out sprint (against the same braking force for every subject). Sixty healthy male subjects participated in the study. The ergometer system used in this study has three operating modes: the isokinetic mode (maintaining pedal crank velocity constant at a present level), a revolution dependent mode and a revolution independent mode. In all three operating modes the effective forces are monitored by means of strain gauge. All subjects performed a single all-out sprint against a braking force of 20 Newton and an all-out isokinetic cycling test consisting of ten 10 s bouts of maximal cycling at speeds ranging from 50 rpm to 140 rpm. In both tests, irrespective of which test mode was used, the mean power for a complete crank revolution showed parabolic relationships to crank velocity. For the isokinetic test, the subjects showed a peak power (IsoWpeak) of 15.3+/-1.7 W/kg corresponding to an optimal velocity of 115+/-8.6 rpm. For the force-velocity test NonisoWpeak (the highest power obtained at any time during the test) was 14.4+/-1.9 W/kg and was achieved at a pedalling rate of 127+/-14 rpm. IsoWpeak was significantly higher than NonisoWpeak (p<0.001) but there were no significant differences between NonisoWpeak and IsoWmax (maximal mean power for each full crank revolution) for the revolutions from 90 rpm to 140 rpm. Though, NonisoWpeak and IsoWpeak are significantly different, there was a strong relationship between NonisoWpeak and IsoWpeak (r = 0.7158, p<0.001). There was also a strong relationship between NonisoWpeak and IsoWmax for the revolutions from 50 rpm to 120 rpm (p<0.001) and at 130 rpm (p<0.01).

[Principles of muscle efficiency in weightlessness]. / Grundlagen der muskulären Leistungsfähigkeit unter Bedingungen der Schwerelosigkeit.

Depending on the time spent in a space station, weightlessness causes varying changes to various organs and regulatory mechanisms of the human organism, among them the structures of the active and passive locomotor system. Experience has shown that regular physical activity using varying forms of training is necessary to keep astronauts and cosmonauts healthy, efficient and fit for work and to prepare them for a safe return to terrestrial conditions. One of the main tasks of physical activity is therefore to counteract the changes in the neuromuscular function, muscle strength, endurance and fatigability under conditions of weightlessness. So far, the diagnostics of these changes was limited to dynamometric measurements before and after space flights as no dynamometric method had been devised which was precise enough under conditions of weightlessness. The development and the introduction of the dynamoergometer Motomir is described against the background of previous results obtained by dynamometric, ergometric, morphometric, biochemical, histochemical and neuromuscular examinations before and after missions of varying duration under conditions of weightlessness. This device was used for the first valid and reproducible examinations of muscle strength and endurance aboard the space station Mir during the Austro-Russian space mission Austromir. The results of the examinations with this speed-controlled dynamometer and training device obtained during a short-term flight of 10 days and a long-term flight of 6 months are described and compared to previous results in the literature. Based on the existing training devices, training methods and training plans and the results of the Motomir Study, plans for devices and methodologies for future long-term space flights of up to 3 years' duration will be discussed. Finally, the possible use of a speed-controlled dynamometer and training device for rehabilitation on earth after injuries, surgery and immobilization of the active and passive locomotor system as well as in the bed-rest syndrome is being presented.