Dirk Büsch’s research while affiliated with Carl von Ossietzky University of Oldenburg and other places

In this paper, we describe two studies on the association among long-term developmental outcomes and relative age effects. To extend or compliment the cross-sectional work done previously, these studies take different approaches to investigate the association of relative age effects on long-term development. In the first, a retrospective approach is taken, while in the second, developmental data for players over a 4-year period is considered. In study 1 the association between relative age effects and later performance at the adult level is presented. The results show different patterns for females and males. In the second study, development during the national youth development system in handball, over four points in time, are presented. Again, changes over time in birth quartile distribution can be seen. These studies suggest relative age researchers should embrace longitudinal designs. These types of approaches would allow explorations of the association of other variables with the observed relative age effects.

In the last thirty years research on relative age effects (RAEs) has exploded in numbers. However, the stability and variability of these effects have hardly been investigated. The three aims of this retrospective study were first to investigate the stability and variability of RAEs over 17 years, second to compare these effects for young female and male athletes, and third to compare these effects between selected and non-selected athletes relative to variability estimates from 17 years prior to assess possible changes in athlete development trends. For this study, birth dates were provided for all participants of the talent selection camps by the German Handball Federation from 2008 to 2024. Results show that first while some variability was observed, the effects remained stable. Second, there are only small differences between sexes in general, although these increased with selection. And thirdly, that selections create stronger effects for male athletes, but not for female ones. Taken together, this study provides an interesting picture of the variability and stability of relative age effects over 17 years.

Background/Objectives: Core strength diagnostics often focus on measuring core endurance rather than maximal core strength or core power. This study investigates whether core strength can be considered as a general ability that can be measured by a single core strength test or whether it needs to be differentiated into several components. Methods: Forty-two adult sports students (nfemale = 20; nmale = 22; age: 24.0 ± 2.9 years; body height: 179.0 ± 9.8 cm; body mass: 75.2 ± 12.7 kg; body fat: 18.0 ± 6.8%) participated in two randomized testing sessions in a laboratory setting. Standard measurements, such as peak rate of force development (pRFD), maximal voluntary contraction (MVC), and holding time, were taken isometrically during four exercises (ventral, dorsal, and lateral right and left). Results: A principal component analysis (PCA) extracted three principal components from twelve different core strength variables. The three identified components explained 73.3% of the total variance and were labeled as (a) maximal core strength, (b) core endurance, and (c) core power. Conclusions: The results suggest three principal components of the core strength construct, as well as their differentiation, may be imperative. These findings should be taken into account in sport science and sports practice as they may be helpful in planning sport-specific diagnostic, performance-oriented training, and injury prevention programs.

Thieschäfer, L, Dos’Santos, T, and Büsch, D. Cutting technique modification: a way to improve movement quality and develop agility in youth? J Strength Cond Res XX(X): 000–000, 2024—High-quality cutting technique is essential for agility development and safer cuttings in adolescent athletes. Certain sidestep techniques and kinematics are characteristic of high movement quality and are associated with both, faster performance and lower knee joint loading (i.e., reduced anterior cruciate ligament injury risk). The aim of this study was to determine the effects of a 6-week, side step, technique modification training intervention targeting specific kinematics on agility performance and movement quality. Twenty-two adolescent American football players were recruited for a nonrandomized, controlled, intervention study. For 6 weeks, an intervention group (IG) of 11 players participated in 25-minute cutting technique training sessions integrated into team training twice a week, whereas a control group (CG) of 11 players continued their usual training routine. Agility performance was assessed based on percentage-based change of direction deficit (CODDp) obtained during reactive agility tests at 45° and 90° angles. The Cutting Movement Assessment Score (CMAS) qualitative screening tool was used to assess 2D high-speed videos of the cuts for movement quality. The significance level was set at α = 0.01. The intervention effectively altered players' sidestep technique irrespective of cutting angle with large time × group interaction effects observed for CMAS ( = 0.82). Statistical and practical significant improvements in CMAS pre-to-post intervention were evident in the IG (−2.30 ≤ g ≤ −1.75; 313.87 ≤ BF 10 ≤ 2,342.00), whereas deteriorations were found in the CG for 90° ( g = 1.38; BF 10 = 64.21). However, in both groups, no statistically significant differences in CODDp were observed pre-to-post intervention (0.019 ≤ p ≤ 0.586; 0.34 ≤ BF 10 ≤ 3.59). The cutting technique modification training meaningfully improved movement quality, without negatively affecting agility performance, and can be used by practitioners to foster a safe technical foundation for subsequent agility development in adolescent athletes.

Previous works have suggested a high prevalence of painkiller intake (PI) among sport students but also improved health literacy (HL) for sports-active students than for sports-inactive students. Since health-related content also forms part of the sport science curriculum, the study focuses on these seemingly paradoxical results. Music students who are also physically active through their instrumental practice, who act in an area with increased PI and who have no health-related teaching content in their curriculum composed the comparison group. Therefore, this study investigated the prevalence of PI and HL in cohorts of sport (n = 222; 54.5% female) and music students (n = 89; 67.4% female) using a cross-sectional online survey in Lower Saxony, Germany. The hypothesis tests were validated by calculating frequentist and Bayesian statistics. The results show that 50.9% of sport and 28.1% of music students exhibit PI concerning their study programs, often for prophylactical purposes and in the presence of low HL levels. The weak negative correlation between PI and HL was not statistically confirmed and requires further research with improved test power. Regarding the possible health consequences of an inconsiderate PI, target group-specific prevention is indicated to increase general health awareness and HL.

Background Childhood obesity is associated with various health outcomes. Restrictive measures to contain the spread of the Coronavirus Disease 2019 (COVID-19) pandemic, like lockdowns and school closures, affected children’s daily structure, physical activity, dietary habits, and sleep quality, possibly exacerbating risk factors for childhood obesity and higher body mass index (BMI) in children. Poor socioeconomic conditions may have led to relatively higher risk for elevated BMI levels following pandemic measures. In this study, the impact of measures related to the COVID-19 pandemic on the BMI of third graders was investigated regarding children’s socioeconomic background (SEB). Methods Data from 41,728 children (8.84 ± 0.56 years, 20,431 female) were collected in the context of a cohort study. Children were tested either before the pandemic (preCOVID: Sept2017–March2020, n = 26,314), or following the first (postLDI: Aug2020–Dec2020, n = 6657) or second lockdown in Germany (postLDII: Aug2021–Jan2022, n = 8757). SEB was based on the official school type classification of the state of Berlin. Outcome was BMI standard deviation scores (SDS). Results Significant effects of Time and SEB revealed elevated BMIs in postLDI (M = 0.23, p = 0.011) and postLDII (M = 0.22, p = 0.011) compared to preCOVID (M = 0.17) cohorts and higher BMIs for children with lower SEB (b = − 0.13, p < 0.001). A significant Time × SEB interaction indicated that the effect of SEB on children’s BMI increased in response to lockdowns, especially in postLDII (b = − 0.05, p = 0.006). Results suggest that the COVID-19-related measures lead to increased BMI in children, and that children of lower SEB were at particular risk for higher BMIs following lockdowns. Conclusions These findings highlight the dependency of children’s BMI on societal circumstances. Over the course of two lockdowns in Germany, children have experienced BMI increments, particularly in low socioeconomic areas. Authorities are called into action to counteract increasing rates of childhood weight by promoting physical activity of children and establishing related post-pandemic offers.

Background: The reduction of muscular hypertonia is important in the treatment of various diseases or rehabilitation. This study aims to test the efficacy of a 5 Hz mechanical muscle stimulation (tapotement massage) in comparison to a 5 Hz repetitive peripheral magnetic stimulation (rPMS) on the neuromuscular reflex response. Methods: In a randomized control trial, 15 healthy volunteers were administered with either 5 Hz rPMS, tapotement massage, or rPMS sham stimulation. The posterior tibial nerve was stimulated with rPMS and sham stimulation. The Achilles tendon was exposed to a mechanically applied high-amplitude 5 Hz repetitive tendon tapotement massage (rTTM). The tendon reflex (TR) was measured for the spinal response of the soleus muscle. Results: After rPMS, there was a reduction of the TR response (−9.8%, p ≤ 0.034) with no significant changes after sham stimulation. Likewise, TR decreased significantly (−17.4%, p ≤ 0.002) after Achilles tendon tapotement intervention. Conclusions: These findings support the hypothesis that both afferent 5 Hz sensory stimulations contributed to a modulation within the spinal and/or supraspinal circuits, which resulted in a reduction of the spinal reflex excitability. The effects could be beneficial for patients with muscle hypertonia and could improve the functional results of rehabilitation programs.

Sports science as an empirical science produces study results that are to be interpreted hypothesis-oriented. The validity of the interpretation of statistically and practically significant results depends on the one hand on the theoretical foundation of the research question and on the other hand on the concrete methodological procedure in intervention studies. Considering hypotheses at the empirical-content and statistical level, recurring interpretation difficulties arise when numbers are translated into words or recommendations for action. On the basis of two examples, a discussion in the scientific community is to be initiated, which could be continued in this journal in case of corresponding interest in methodological issues.

One of the most convincing studies about the importance of the cutoff date in relative age effects was when Helsen et al. (2000) showed that a shift in the date directly resulted in a change of birth month distributions in soccer. Over the past four decades, the role of the birth year has also been associated with relative age effects (as reflected in constant year effects). In this investigation, two studies attempted to replicate the shift of birth year distributions caused by a change in birth years in international female handball. In Study 1, the results from the female handball world championship 2017 showed a significant within‐year effect overall and a constant year effect for players born 1988 and after. A second study was conducted with female players from world championships in 2009, 2011, 2013, and 2015. Results demonstrated small effect sizes for most tests. However, there was an unexpected trend toward a constant year effect shift at the age of 28 years. Several hypotheses are presented as an explanation for this trend.