Christian Baumgart

Match Running Performance and Success Across a Season in German Bundesliga Soccer Teams

The aim of the study was to quantify the association between match running performance and success across a season in soccer teams competing within a European top league. We analyzed the match running performance data of all soccer teams from the German Bundesliga across the season 2012/13 (306 matches). The following match running performance data were used: total distance covered as well as number of running activities>18.0 km/h and > 22.7 km/h. Depending on the teams ball possession status, all match running performance data were also analyzed as those with and without ball possession. The success across the season was defined as the final competition points accumulated. The match running performance alone was not significantly correlated with the final points accumulated (best r=0.24; p=0.34). In contrast, positive-significant correlations were observed for the match running performance with ball possession (best r=0.77; p<0.01). However, of these latter correlations, only the total distance covered with ball possession was a significant predictor (p<0.01) and accounted for 60% of the variance (R(2)=0.60) in the final points accumulated. It is concluded that it is not the match running performance alone that is important for achieving success in German Bundesliga soccer teams, but rather its relation to technical/tactical skills with respect to ball possession.

Running Activity Profile of Adolescent Tennis Players During Match Play

The aims of this study were (1) to assess the running activities of adolescent tennis players during match play with respect to velocity, acceleration, and deceleration; (2) to characterize changes in these activities during the course of a match; and (3) to identify potential differences between winners and losers. Twenty well-trained adolescent male athletes (13 ± 1 y) played one simulated match each (giving a total of 10 matches), during which distances covered at different velocity categories (0 to < 1, 1 to < 2, 2 to < 3, 3 to < 4, and ≥ 4 m·s(-1)) and number of running activities involving high velocity (≥ 3 m·s(-1)), acceleration (≥ 2 m·s(-2)), and deceleration (≤ -2 m·s(-2)) were monitored using a global positioning system (10 Hz). Heart rate was also assessed. The total match time, total distance covered, peak velocity, and mean heart rate were 81.2 ± 14.6 min, 3362 ± 869 m, 4.4 ± 0.8 m·s(-1), and 159 ± 12 beats·min(-1), respectively. Running activities involving high acceleration (0.6 ± 0.2 n·min(-1)) or deceleration (0.6 ± 0.2 n·min(-1)) were three times as frequent as those involving high velocity (0.2 ± 0.1 n·min(-1)). No change in the pattern of running activities (P ≥ .13, d ≤ 0.39) and no differences between winners and losers (P ≥ .22, d ≤ 0.53) were evident during match play. We conclude that training of well-trained adolescent male tennis players need not focus on further development of their running abilities, since this physical component of multifactorial tennis performance does not change during the course of a match and does not differ between the winners and losers.

Comparison Between Three Different Endurance Tests in Professional Soccer Players

Abstract Hoppe, MW, Baumgart, C, Sperlich, B, Ibrahim, H, Jansen, C, Willis, SJ, and Freiwald, J. Comparison between three different endurance tests in professional soccer players. J Strength Cond Res 27(1): 31–37, 2013—The aims of this study were (a) to assess and correlate interval shuttle run test (ISRT) performance, maximum oxygen uptake (V[Combining Dot Above]O2max), running economy (RE), running velocity at the first rise in blood lactate concentrations above baseline (vLT) and running velocity at 4 mmol·L−1 blood lactate concentration (v4) in professional soccer players and (b) to investigate whether a correlation exists between the respective results of time to exhaustion (Tlim) from continuous and intermittent endurance tests, respectively. Eleven male professional field soccer players (mean ± SD: age 23.8 ± 3.0 years, V[Combining Dot Above]O2max 58.2 ± 4.9 ml·kg−1·min−1) completed a continuous Incremental Test with lactate measurements to determine vLT and v4, a continuous Ramp Test with gas exchange analysis to determine V[Combining Dot Above]O2max and RE, and an intermittent ISRT to determine intermittent endurance capacity during the first week of preseason preparation. There were significant correlations between ISRT performance and V[Combining Dot Above]O2max (r = 0.70, p < 0.05), and between Tlim in both continuous endurance tests (r = 0.89, p < 0.01). Between all other variables no significant correlations were found overall (best r = 0.60, p > 0.05). The assessment of all values of V[Combining Dot Above]O2max, RE, vLT, and v4 should be included when investigating aerobic endurance performance among groups or over time in professional soccer players. Although V[Combining Dot Above]O2max, RE, vLT, and v4 have been regarded as important factors of aerobic performance in endurance related sports, the present data revealed that V[Combining Dot Above]O2max was the only factor, which correlated with intermittent endurance capacity in professional soccer players. Hence, V[Combining Dot Above]O2max should be increased through soccer-specific training interventions including universal agility components. The Tlim in continuous and intermittent endurance tests differs and is therefore an independent endurance performance factor in professional soccer players.

Effects of Static Stretching and Playing Soccer on Knee Laxity

Objective:This study investigated exercise-induced effects of static stretching and playing soccer on anterior tibial translation (ATT) of the knee joint. Design:Randomized controlled trial. Setting:University biomechanics laboratory. Participants:Thirty-one athletes were randomly assigned into a stretching (26.9 ± 6.2 years, 1.77 ± 0.09 m, 67.9 ± 10.7 kg) and a control group (27.9 ± 7.4 years, 1.75 ± 0.08 m, 72.0 ± 14.9 kg). Thirty-one amateur soccer players in an additional soccer group (25.1 ± 5.6 years, 1.74 ± 0.10 m, 71.8 ± 14.8 kg). All participants had no history of knee injury requiring surgery and any previous knee ligament or cartilage injury. Interventions:The stretching group performed 4 different static stretching exercises with a duration of 2 × 20 seconds interspersed with breaks of 10 seconds. The soccer group completed a 90-minute soccer-specific training program. The control group did not perform any physical activity for approximately 30 minutes. Main Outcome Measures:Anterior tibial translation was measured with the KT-1000 knee arthrometer at forces of 67 N, 89 N, and maximal manual force (Max) before and after the intervention. Results:There was a significant increase in ATT after static stretching and playing soccer at all applied forces. Maximal manual testing revealed a mean increase of ATT after static stretching of 2.1 ± 1.6 mm (P < 0.0005) and after playing soccer of 1.0 ± 1.5 mm (P = 0.001). The ATT increase after static stretching at 67 and 89 N is significantly higher than in controls. At maximum manual testing, significant differences were evident between all groups. Conclusions:Static stretching and playing soccer increase ATT and may consequently influence mechanical factors of the anterior cruciate ligament. The ATT increase after static stretching was greater than after playing soccer. Clinical Relevance:The observed increase in ATT after static stretching and playing soccer may be associated with changes in kinesthetic perception and sensorimotor control, activation of muscles, joint stability, overall performance, and higher injury risk.

Validity and reliability of GPS and LPS for measuring distances covered and sprint mechanical properties in team sports

This study aimed to investigate the validity and reliability of global (GPS) and local (LPS) positioning systems for measuring distances covered and sprint mechanical properties in team sports. Here, we evaluated two recently released 18 Hz GPS and 20 Hz LPS technologies together with one established 10 Hz GPS technology. Six male athletes (age: 27±2 years; VO2max: 48.8±4.7 ml/min/kg) performed outdoors on 10 trials of a team sport-specific circuit that was equipped with double-light timing gates. The circuit included various walking, jogging, and sprinting sections that were performed either in straight-lines or with changes of direction. During the circuit, athletes wore two devices of each positioning system. From the reported and filtered velocity data, the distances covered and sprint mechanical properties (i.e., the theoretical maximal horizontal velocity, force, and power output) were computed. The sprint mechanical properties were modeled via an inverse dynamic approach applied to the center of mass. The validity was determined by comparing the measured and criterion data via the typical error of estimate (TEE), whereas the reliability was examined by comparing the two devices of each technology (i.e., the between-device reliability) via the coefficient of variation (CV). Outliers due to measurement errors were statistically identified and excluded from validity and reliability analyses. The 18 Hz GPS showed better validity and reliability for determining the distances covered (TEE: 1.6–8.0%; CV: 1.1–5.1%) and sprint mechanical properties (TEE: 4.5–14.3%; CV: 3.1–7.5%) than the 10 Hz GPS (TEE: 3.0–12.9%; CV: 2.5–13.0% and TEE: 4.1–23.1%; CV: 3.3–20.0%). However, the 20 Hz LPS demonstrated superior validity and reliability overall (TEE: 1.0–6.0%; CV: 0.7–5.0% and TEE: 2.1–9.2%; CV: 1.6–7.3%). For the 10 Hz GPS, 18 Hz GPS, and 20 Hz LPS, the relative loss of data sets due to measurement errors was 10.0%, 20.0%, and 15.8%, respectively. This study shows that 18 Hz GPS has enhanced validity and reliability for determining movement patterns in team sports compared to 10 Hz GPS, whereas 20 Hz LPS had superior validity and reliability overall. However, compared to 10 Hz GPS, 18 Hz GPS and 20 Hz LPS technologies had more outliers due to measurement errors, which limits their practical applications at this time.

DIFFERENT ENDURANCE CHARACTERISTICS OF FEMALE AND MALE GERMAN SOCCER PLAYERS

The aims of the present study were to assess gender differences regarding lactate threshold and intermittent shuttle run performance in female and male soccer players as well as to investigate the relationships between both endurance characteristics in both genders. Fourteen female (1st division) and thirteen male (4th division) soccer players completed an incremental test (IT) to determine running velocities at 2 and 4 mmol · l−1 blood lactate (v2 and v4) and maximum velocity (vmax) as well as an interval shuttle run test (ISRT) to determine running distance. Based on v2 and v4 and their percentages in relation to vmax, three intensity zones were calculated: a low lactate zone (v4). Female soccer players have a lower v4 (8.2%), vmax (11.3%) and ISRT distance (31.6%). No gender difference was found in v2. In contrast to males, ISRT distance correlates with vmax as well as with v2 and v4 in female soccer players. The intensity zones v4 differ between genders. The present study revealed that gender differences increase when the running performance is intermittent including change of directions. In both genders, different relationships between lactate threshold and intermittent shuttle run performance exist. During incremental testing, the running performances of female and male players reflect different distributions of aerobic and anaerobic metabolic pathways. The revealed gender differences should be considered for soccer endurance training.

Changes of standard physiological-perceptual markers and circulating MicroRNAs in response to tennis match-play: A case report of two elite players.

Abstract This study aimed to describe the acute changes of both standard physiological-perceptual markers and circulating microRNAs in response to tennis match-play in a detailed case report. Two elite male baseliners with comparable tennis experience were tested for anthropometric and fitness related variables and played 2 h of match-play on a red-clay court. The changes of standard physiological-perceptual markers including the heart rate, lactate concertation, creatine kinase activity, urea concentration and rating of perceived exertion as well as circulating microRNA-133a, -486 and -126 expression rates were examined at 10 different time-points (i.e., pre, during and up to 24 h post match-play). Player 2 had lower fitness related variables, but a higher heart rate, lactate concentration, creatine kinase activity and rating of perceived exertion during play than player 1. Player 2 showed an increase in all microRNAs (≤3.83-fold), most evident post match-play, whereas player 1 demonstrated a decrease (≤0.41-fold). The time-course in the changes of all standard physiological-perceptual markers was similar in both players, whereas this of the microRNAs was different. It was concluded that the relative changes of the circulating microRNA-133a, -486 and 126 expression rates of both players differed in response to tennis match-play with respect to the experienced physiological-perceptual stress and the underlying fitness level. Therefore, circulating microRNAs can serve as additional biomarkers for tennis exercise physiology and may be assessed together with standard markers to conclude whether key cellular regulatory processes were induced in response to match-play.

PRÄVENTION: Prävention im Fußballsport

Zusammenfassung Im Beitrag werden die Anforderungen im Leistungsfusball beleuchtet. Laufumfange und -intensitaten, Wettkampfhaufigkeiten und die korperlichen Voraussetzungen werden analysiert. Es folgt eine epidemiologische Analyse von Verletzungen und Verletzungslokalisationen und deren Ursachen. Auf der Basis der Analyse werden Konsequenzen fur die Pravention im Fusball vorgeschlagen. Angesprochen werden Betreuungsmasnahmen, motorisches Lernen, Koordination und konditionelle Aspekte. Zum Ende werden Diagnostik und Testverfahren im kurz-, mittel- und langfristigen Bereich besprochen. Aufwarmen, Dehnen, Krafttraining und betreuende Masnahmen als Pravention gegenuber Verletzungen werden detailliert erlautert.

Phase-Specific Ground Reaction Force Analyses of Bilateral and Unilateral Jumps in Patients With ACL Reconstruction:

Background: In patients who have undergone anterior cruciate ligament (ACL) reconstruction, there is a weak correlation between subjective evaluation of knee function on questionnaires and clinical or biomechanical test results. Hypothesis: Patients with lower subjective knee function will demonstrate lower ground-reaction forces (GRFs) in the operated leg and greater GRF asymmetries in both phase-specific and functional data analysis (FDA) approaches compared with patients with higher subjective knee function. Study Design: Descriptive laboratory study. Methods: The GRFs of the operated and nonoperated legs of 40 patients who previously underwent ACL reconstruction (patellar tendon) were analyzed during unilateral and bilateral countermovement jumps at a mean 2.5 years after surgery. The patients were separated into 2 groups depending on their International Knee Documentation Committee (IKDC) Subjective Form score: low IKDC and high IKDC. Results: Both phase-specific and FDA approaches showed lower GRF values in the operated compared with the nonoperated leg within the low-IKDC group during bilateral jumps. Moreover, lower GRF values were also present in the operated and nonoperated legs in the low-IKDC group compared with those of the high-IKDC group. Differences in GRFs were predominantly observed during the eccentric deceleration phase of jumping. Conclusion: Patients with previous ACL reconstruction who have limited subjective knee function have lower GRF values and greater GRF asymmetries, suggesting the use of interlimb compensation strategies. Clinical Relevance: The study results lead to a better understanding of the motor control needed during the eccentric and concentric movement phases of unilateral and bilateral jumps in patients who have undergone ACL reconstruction.

Variability of metabolic power data in elite soccer players during pre-season matches

Abstract This study aimed to determine the within-subject variability of GPS-derived metabolic power data in elite soccer players across several pre-season matches and compare the variability of high metabolic power, velocity, acceleration and deceleration running. Additionally, differences in metabolic power data among playing positions and relationships with various physical abilities were also investigated. Metabolic power data from 12 outfield starting players competing in the German Bundesliga were collected during five pre-season matches using GPS-technology (10 Hz). The players were also tested for speed, agility, power and intermittent endurance. Variability of global metabolic power data such as energy expenditure (CV = 2.2-7.0%) was lower than that for high-intensity including time ≥20 W·kg-1 (CV = 14.0-26.2%). Variability of high metabolic power (≥20 W·kg-1; CV = 14.1 ± 3.5%) was comparable to that of high velocity (≥15.5 km·h-1; CV = 17.0 ± 6.2%), acceleration (≥3 m·s-2; CV = 11.1 ± 5.1%) and deceleration running (≤-3 m·s-2; CV = 11.9 ± 4.5%) (p > 0.05, ES < 0.2). Defenders had a largely higher overall energy expenditure than midfielders and attackers (p < 0.01, ES > 0.6). Overall energy expenditure and cost were largely to very largely correlated with 5 m speed and 22 m agility sprint time and counter movement jump height (r = -0.70-0.69, p < 0.05). The detected variability indicates that global GPS-derived metabolic power data in elite soccer players from a single preseason match should be preferably used for practical applications. Contrary, high-intensity indicators should be interpreted cautiously and repeated match observations are recommended to establish meaningful high-intensity profiles of the players. Differences among playing positions and relationships with explosive physical abilities indicate that metabolic power analyses can provide new insights into the mechanics and energetics of soccer.