Thomas Muehlbauer

Background: The effects of training interventions on interlimb balance performance have been recently investigated. However, no comparison was conducted between the impact of a single-mode versus combined training modality, whereby complementary adaptations are suggested for the latter. Objective: Thus, we investigated the effects of a single-mode versus combined training modality on interlimb static and dynamic balance performance in soccer players. Methods: Young male soccer players ( N = 57, Tier level 3) were randomly allocated to a unilateral single-mode balance training (BT) group ( n = 17, age: 13.8 ± 1.5 years), a unilateral combined balance and plyometric jump training (BT + PT) group ( n = 20, age: 14.1 ± 1.5 years) or an active control (CON) group ( n = 20, age: 14.2 ± 1.6 years). Training was conducted in-season for nine weeks (two sessions per week) using the non-dominant leg. Pre- and post-intervention, unipedal balance performance was assessed for both legs under static (unipedal stance only) and dynamic (unipedal stance with continuous leg swing) task conditions while increasing the difficulty level (i.e., gradual reduction of the base of support). Binary (success rate) and metric (center of pressure [CoP] indices, limb symmetry index [LSI]) parameters of postural control were calculated. Results: Both training modalities yielded significant improvements in interlimb static and dynamic postural control, with greater effects in the single-mode BT group for the parameter success rate and in the combined BT + PT group for the CoP-based indices. Significant improvements in the LSI occurred irrespective of the training modality. Conclusion: Both, single-mode BT (binary outcome) and combined BT + PT (metric outcome) appear to be effective in improving interlimb static and dynamic postural control in young male soccer players. Due to the floor and ceiling effects across outcome domains, it cannot be concluded that one training mode is superior to the other. However, the more in-depth analysis (i.e., CoP-based indices) yields findings in favor of the combined BT + PT and suggests that regulatory processes, in particular, benefit from this training modality.

Background/Objectives: Emerging evidence shows that dual tasking as well as the restriction of arm movements independently lead to detrimental effects on walking performance. However, it is unclear whether the deteriorations are more pronounced when applied together and if children (i.e., due to ongoing maturation processes) perform differently compared to young adults. This study investigated the influence of different arm movement strategies on subjective and objective markers related to beam walking under single-task (ST) and dual-task (DT) conditions in children and young adults. Methods: Twenty-six children (age: 11.3 ± 0.6 years) and 30 young adults (age: 23.2 ± 2.8 years) walked three meters on a balance beam with free and restricted (i.e., arms crossed over the chest) arm movements in a random order while concurrently performing a cognitive task (i.e., serial subtractions) or not. Walking outcomes (i.e., gait speed, cadence) were measured and used as objective markers. Self-reported task-related perceptions (i.e., balance confidence, fear of falling, perceived instability, conscious balance processing) were assessed and used as subjective indicators. Results: Walking under DT conditions (i.e., main effects of task) detrimentally influenced subjective task-related perceptions and walking outcomes, but using free arm movements (i.e., task × arm interactions) mitigated these deteriorations. Further, children exhibited largely stable levels of conscious balance processing, whereas young adults demonstrated overall higher levels along with pronounced differences between ST and DT walking when arm movements were unrestricted (i.e., group × task × arm interaction). Conclusions: These findings indicate that free arm movements seem to constitute a simple yet effective complementary ‘upper-body strategy’ that enhances postural control during a cognitively demanding walking task. Further, age differences imply that young adults compensate demanding walking conditions (i.e., DT walking with restricted arms) by elevated conscious processing of balance (i.e., a shift from automated to more conscious attention towards postural control).

Background: It has been shown that unilateral balance training (BT) enhances balance and neuromuscular performance in the trained and untrained leg and thus has the potential to reduce side-to-side differences. However, it is unresolved how effective unilateral single-mode BT compared to unilateral combined balance and plyometric training (BT + PT) is in reducing interlimb asymmetry. Thus, we examined the impact of both training modalities on soccer players’ interlimb asymmetry in balance and neuromuscular performance. Methods: Sixty male elite youth soccer players were randomly assigned to a unilateral single-mode BT group ( n = 20), a unilateral combined BT + PT group ( n = 22) or an active control group ( n = 22). All groups trained for nine weeks (2 sessions/week) with their non-dominant leg. The interventions included balance exercises for the single-mode BT group, balance and plyometric exercises for the combined BT + PT group and stretching exercises for the active control group. Training progression was achieved by manipulating sensory input (balance exercises), the number of floor contacts (plyometric exercises), or the duration of the stretching exercises. Before and after the intervention period, performance in the Y Balance Test – Lower Quarter (YBT–LQ) and the single leg drop landing (SLDL) test as well as leg muscle activity were assessed. The magnitude of interlimb differences was quantified by calculating the limb symmetry index (LSI) and compared using repeated measures analysis of variance (significance level: p < .05). Results: The analysis revealed significant main effects of test (pre vs. post) for the LSI values of the YBT–LQ (anterior reach: η _p ² = .07; posterolateral reach: η _p ² = .11) and activity of the gastrocnemius muscle ( η _p ² = .33) but not for the SLDL test. Further, a significant test×group interaction was detected for the LSI value of the anterior reach ( η _p ² = .10) and post-hoc analyses yielded a significant LSI reduction for the unilateral single-mode BT group ( d = .79) only. Conclusion: Nine weeks of unilateral single-mode BT and combined BT + PT proved to be effective and feasible (attendance rates of ≈ 99%–100%). In particular, unilateral single-mode BT appears to be suitable for reducing the LSI value of the YBT–LQ anterior reach, which is a predictor for time loss non-contact lower limb injuries.

Background: Emerging evidence highlights that adaptations in postural control induced by long-term motor practice are specific to the requirements in which the balance task is performed. In addition, the adaptations appear to be limb-specific, and as a result, may lead to differences in task failure when increasing the level of balance task difficulty. Thus, we determined differences in the percentage of participants with task failure (i.e., dropouts) during dynamic balance assessments for each limb while increasing the level of task difficulty in trained compared to untrained individuals.Methods: Soccer players (n = 64, age: 14.0 ± 1.8 years) with different levels of training experience (i.e., 2–5 or 6–9 years), swimmers (n = 73, age: 13.8 ± 2.7 years) and non-athletes (n = 60, age: 14.1 ± 1.1 years) performed the unipedal stance with the dominant and non-dominant leg under dynamic single (balance task only) and dual (balance and a concurrent motor task) task conditions with an increasing difficulty level (i.e., progressive reduction of the base of support). The percentage of participants remaining per completed difficulty level was analysed by type of sport, level of training experience, and leg dominance.Results: In both tasks, the percentage of individuals remaining per completed difficulty level decreased as the level of task difficulty increased, irrespective of the individual's training background. Further, significantly lower dropouts were found in soccer players compared to swimmers and non-athletes. However, no significant differences were detected between soccer players with diverging levels of training experience or with respect to limb dominance.Conclusions: The lower dropouts in soccer players compared to swimmers and non-athletes suggest sport-specific benefits in postural control for balance tasks with increasing difficulty level. However, this benefit is not superior in soccer players with more compared to less training experience and for the dominant than the non-dominant limb. These findings indicate that soccer players exhibit better postural control with both the dominant and non-dominant leg compared to swimmers and untrained individuals, which is maintained even with increasing balance task difficulty.

Little is known about how individual and contextual factors affect inter-limb differences in balance performance. Thus, we investigated how these factors influence inter-limb asymmetry in balance. Sixty-four soccer players with diverging levels of training experience (i. e., 2–5 or 6–9 years), 73 swimmers, and 60 age-matched non-athletes performed balance tests with different task specificity (i. e., ecological vs. non-ecological). The magnitude of inter-limb differences was quantified by calculating the limb symmetry index (LSI). Inter-limb performance differences were significantly (p=0.012) lower in athletes with (i. e., soccer players) than without (i. e., swimmers) the preferential use of one leg for postural control. However, differences between limbs did not significantly differ among players with diverging levels of training experience. Further, the observed inter-limb differences in soccer players emerged during ecological test conditions only. Our results suggest that the predominant use of one limb compared to the other for balance requirements does not necessarily lead to a large magnitude of inter-limb asymmetry in soccer players and is also not significantly influenced by the level of training experience. However, from a practitioners’ perspective, ecological as opposed to non-ecological test conditions seem to be more suitable for detecting inter-limb asymmetry in soccer players.

The current study aimed to determine the effects of low (i.e., balance task only) versus high (i.e., balance task combined with an additional motor task like dribbling a basketball) balance training complexity (6 weeks of training consisting of 2 × 30 min balance exercises per week) on measures of static and dynamic balance in 44 healthy male adolescents (mean age: 13.3 ± 1.6 years). Irrespective of balance training complexity, significant medium- to large-sized pretest to posttest improvements were detected for static (i.e., One-Legged Stance test, stance time [s], 0.001 < p ≤ 0.008) and dynamic (i.e., 3-m Beam Walking Backward test, steps [n], 0.001 < p ≤ 0.002; Y-Balance-Test-Lower-Quarter, reach distance [cm], 0.001 < p ≤ 0.003) balance performance. Further, in all but one comparison (i.e., stance time with eyes opened on foam ground) no group × test interactions were found. These results imply that balance training is effective to improve static and dynamic measures of balance in healthy male adolescents, but the effectiveness seems unaffected by the applied level of balance training complexity.

Objective: In healthy children, there is evidence of improvements in static and dynamic balance performance following balance training. However, the time-course of balance training-related changes is unknown. Thus, we determined the effects of balance training after one, three, and six weeks of exercise on measures of static and dynamic balance in healthy children (N = 44, 20 females, mean age: 9.6 ± 0.5 years, age range: 9–11 years). Results: Participants in the intervention group (2 × 25 min balance exercises per week) compared to those in the control group (2 × 25 min track and field exercises and soccer practice per week) significantly improved their static (i.e., by measuring stance time in the One-Legged Stance test) and dynamic (i.e., by counting step number in the 3-m Beam Walking Backward test) balance performance. Late effects (after 6 weeks) occurred most frequently followed by mid-term effects (after 3 weeks) and then early effects (after 1 week). These findings imply that balance training is effective to improve static and dynamic measures of balance in healthy children, whereby the effectiveness increases with increasing training period. Trial registration: Current Controlled Trials ISRCTN16518737 (retrospectively registered at 24th August, 2023).

Maximal strength is a significant factor in achieving peak performance and injury prevention in athletes. In individualization strategies for the efficient development of athletes, it is necessary to consider the respective components separately. The purpose of this study was to systematically examine the effects of the different cycle phases on isometric, isokinetic, and dynamic maximum strength. A systematic literature review was conducted; databases were searched from January 1960 to September 2023. The included studies focused on the expression of maximal strength in the earlier follicular phase as well as at least one comparative phase. Of the initial 707 articles identified, 22 met the selection criteria and were included. The studies considered a total of 433 subjects. Our results revealed medium effects (weighted mean standardized mean difference (SMD) = 0.60; seven studies) for isometric maximal strength in favor of the late follicular phase, small effects (weighted mean SMD = 0.39; five studies) for isokinetic maximal strength in favor of the ovulation phase, and small effects (weighted mean SMD = 0.14; three studies) for dynamic maximal strength in favor of the late follicular phase. The results indicate that the early follicular phase is unfavorable for all strength classes. Peak performance in isometric strength is seen in the late follicular phase, whereas isokinetic strength peaks during ovulation. Dynamic strength is optimal in the late follicular phase.

Levels of state and trait anxiety are relevant for performing artists and professional athletes to obtain optimal performance outcomes. However, evidence-based knowledge regarding the effectiveness of psychological interventions on performance anxiety is currently minimal. Thus, the objective of this systematic review with meta-analysis was to characterize, aggregate, and quantify intervention effects on measures of state and trait performance anxiety in performing artists and professional athletes. A systematic search of the literature according to the PRISMA guidelines was conducted on the databases PubMed, Medline, SPORTDiscus, PsycInfo, Embase, and Web of Science from 1 January 1960 to 9 November 2022. The search only included controlled studies employing pre–post measures and excluded performing arts fields that do not depend on fine motor skills. Initially, 1022 articles were identified; after removing duplicates and assessing abstracts and full texts, 20 articles were used to calculate weighted standardized mean differences (SMDs). In terms of state performance anxiety, our results revealed a large overall effect (SMD = 0.88), a medium effect (SMD = 0.62) for studies using scales with total scores (i.e., MPAI-A, STAI), and large effects (cognitive anxiety: SMD = 0.93, somatic anxiety: SMD = 0.92, self-confidence: SMD = 0.97) for studies applying scales with sub-scores (i.e., CSAI-2R)—all in favour of the intervention groups. Regarding trait performance anxiety (e.g., SCAT), we detected a small effect (SMD = 0.32), also favouring the intervention groups. Interventions to reduce performance anxiety in performing artists and professional athletes revealed varying levels of effectiveness ranging from small (trait) to large (state). Therefore, future studies should investigate modalities to increase intervention efficacy, especially for the small-sized changes in trait performance anxiety.