Acute effects of concurrent muscle power and sport-specific endurance exercises on markers of immunological stress response and measures of muscular fitness in highly trained youth male athletes

PURPOSE

To examine the acute effects of concurrent muscle power and sport-specific endurance exercises order on immunological stress responses, muscular-fitness, and rating-of-perceived-exertion (RPE) in highly trained youth male judo athletes.

METHODS

Twenty male participants randomly performed two concurrent training (CT) sessions; power-endurance and endurance-power. Measures of immune response (e.g., white blood cells), muscular-fitness (i.e., counter-movement-jump [CMJ]), RPE, blood-lactate, and -glucose were taken at different time-point (i.e., pre, mid, post, and post6h).

RESULTS

There were significant time*order interactions for white blood cells, lymphocytes, granulocytes, granulocyte-lymphocyte-ratio, and systemic-inflammation-index. Power-endurance resulted in significantly larger pre-to-post increases in white blood cells and lymphocytes while endurance-power resulted in significantly larger pre-to-post increases in the granulocyte-lymphocyte-ratio and systemic-inflammation-index. Likewise, significantly larger pre-to-post6h white blood cells and granulocytes increases were observed following power-endurance compared to endurance-power. Moreover, there was a significant time*order interaction for blood-glucose and -lactate. Following endurance-power, blood-lactate and -glucose increased from pre-to-mid but not from pre-to-post. Meanwhile, in power-endurance blood-lactate and -glucose increased from pre-to-post but not from pre-to-mid. A significant time*order interaction was observed for CMJ-force with larger pre-to-post decreases in endurance-power compared to power-endurance. Further, CMJ-power showed larger pre-to-mid performance decreases following power-endurance, compared to endurance-power. Regarding RPE, significant time*order interactions were noted with larger pre-to-mid values following endurance-power and larger pre-to-post values following power-endurance.

CONCLUSION

CT induced acute and delayed order-dependent immune cell count alterations in highly trained youth male judo athletes. In general, power-endurance induced higher acute and delayed immunological stress responses compared to endurance-power. CMJ-force and RPE fluctuated during both CT sessions but went back to baseline 6 h post-exercise.

Network analysis of associations between anthropometry, physical fitness, and sport-specific performance in young canoe sprint athletes: The role of age and sex

Introduction

Anthropometric and physical fitness data can predict sport-specific performance (e.g., canoe sprint race time) in young athletes. Of note, inter-item correlations (i.e., multicollinearity) may exist between tests assessing similar physical qualities. However, multicollinearity among tests may change across age and/or sex due to age-/sex-specific non-linear development of test performances. Therefore, the present study aimed at analyzing inter-item correlations between anthropometric, physical fitness, and sport-specific performance data as a function of age and sex in young canoe sprint athletes.

Methods

Anthropometric, physical fitness, and sport-specific performance data of 618 male and 297 female young canoe sprint athletes (discipline: male/female kayak, male canoe) were recorded during a national talent identification program between 1992 and 2019. For each discipline, a correlation matrix (i.e., network analysis) was calculated for age category (U13, U14, U15, U16) and sex including anthropometrics (e.g., standing body height, body mass), physical fitness (e.g., cardiorespiratory endurance, muscle power), and sport-specific performance (i.e., 250 and 2,000-m on-water canoe sprint time). Network plots were used to explore the correlation patterns by visual inspection. Further, trimmed means (μ_trimmed) of inter-item Pearson's correlations coefficients were calculated for each discipline, age category, and sex. Effects of age and sex were analyzed using one-way ANOVAs.

Results

Visual inspection revealed consistent associations among anthropometric measures across age categories, irrespective of sex. Further, associations between physical fitness and sport-specific performance were lower with increasing age, particularly in males. In this sense, statistically significant differences for μ_trimmed were observed in male canoeists (p < 0.01, ξ = 0.36) and male kayakers (p < 0.01, ξ = 0.38) with lower μ_trimmed in older compared with younger athletes (i.e., ≥U15). For female kayakers, no statistically significant effect of age on μ_trimmed was observed (p = 0.34, ξ = 0.14).

Discussion

Our study revealed that inter-item correlation patterns (i.e., multicollinearity) of anthropometric, physical fitness, and sport-specific performance measures were lower in older (U15, U16) versus younger (U13, U14) male canoe sprint athletes but not in females. Thus, age and sex should be considered to identify predictors for sport-specific performance and design effective testing batteries for talent identification programs in canoe sprint athletes.

Seasonal Changes in Anthropometry, Body Composition, and Physical Fitness and the Relationships with Sporting Success in Young Sub-Elite Judo Athletes: An Exploratory Study

This exploratory study aimed to monitor long-term seasonal developments in measures of anthropometry, body composition, and physical fitness in young judo athletes, and to compute associations between these measures and sporting success. Forty-four young judoka (20 females, 24 males) volunteered to participate. Tests for the assessment of anthropometry (e.g., body height/mass), body-composition (e.g., lean body mass), muscle strength (isometric handgrip strength), vertical jumping (e.g., countermovement-jump (CMJ) height), and dynamic balance (Y-balance test) were conducted at the beginning and end of a 10-month training season. Additionally, sporting success at the end of the season was recorded for each athlete. Analyses revealed significant time × sex interaction effects for lean-body-mass, isometric handgrip strength, and CMJ height (0.7 ≤ d ≤ 1.6). Post-hoc analyses showed larger gains for all measures in young males (1.9 ≤ d ≤6.0) compared with females (d = 2.4) across the season. Additionally, significant increases in body height and mass as well as Y-balance test scores were found from pre-to-post-test (1.2 ≤ d ≤4.3), irrespective of sex. Further, non-significant small-to-moderate-sized correlations were identified between changes in anthropometry/body composition/physical fitness and sporting success (p > 0.05; -0.34 ≤ ρ ≤ 0.32). Regression analysis confirmed that no model significantly predicted sporting success. Ten months of judo training and/or growth/maturation contributed to significant changes in anthropometry, body composition, and physical fitness, particularly in young male judo athletes.

[Associations between trunk muscle strength and judo-specific pulling performances in judo athletes]

BACKGROUND

 Good trunk stability is an important prerequisite for the mobility of the upper and lower limbs during sport-specific movements. Therefore, trunk muscle strength may represent an important performance determinant for judo-specific movements. This study aimed at evaluating statistical correlations between trunk muscle strength and kinetic parameters during judo-specific pulling movements in judo players.

METHOD

 Twenty-one male sub-elite judo players aged 22 ± 4 years with a mean training volume of 15 ± 4 hours per week participated in this study. Peak isokinetic torque (PIT) of the trunk flexors (PIT_Flex), extensors (PIT_Ex) and rotators (PIT_Rot) was tested using an isokinetic dynamometer (IsoMed 2000). In addition, two kinetic parameters (mechanical work [W], maximal force [F_max]) were analysed using the judo-specific measurement and information system JERGo^©. For this purpose, athletes were asked to do their judo-specific pulling movements while standing and with a dynamic change of position (i. e. Morote-seoi-nage).

RESULTS

 Regarding pulling movements while standing, significant correlations (0.62 ≤ r _P ≤ 0.72) were found between isokinetic tests (PIT_Flex, PIT_Ex, PIT_Rot) and mechanical work during judo-specific movement. Further, significant correlations (0.59 ≤ r _P ≤ 0.65) were detected between isokinetic tests (PIT_Ex, PIT_Rot) and judo-specific pulling movements (F_max). Regarding pulling movements with a change of position, significant correlations (0.47 ≤ r _P ≤ 0.88) were observed between isokinetics (PIT_Flex, PIT_Ex, PIT_Rot) and the kinetic pulling parameters (W, F_max), irrespective of the examined arm. No significant differences in magnitude of correlation coefficients were found between PIT of the trunk flexors, extensors, and rotators and judo-specific movements. Further, the regression analysis indicated that PIT of the trunk extensors is the single best predictor for mechanical work during pulling movements while standing (46.9 %). Trunk rotator PIT is the single best predictor for mechanical work during pulling movements with a change of position (69.4 %).

CONCLUSIONS

 Findings from this study indicate that trunk muscle strength, particularly trunk rotator PIT is associated with kinetic pulling variables during pulling movements with a change of position. This implies that the development of trunk rotator strength could have an impact on pulling movements with a change of position (i. e. Morote-seoi-nage) in judo athletes.

Validation of A New Judo-Specific Ergometer System in Male Elite and Sub-Elite Athletes

Our experimental approach included two studies to determine discriminative validity and test-retest reliability (study 1) as well as ecological validity (study 2) of a judo ergometer system while performing judo-specific movements. Sixteen elite (age: 23 ± 3 years) and 11 sub-elite (age: 16 ± 1 years) athletes participated in study 1 and 14 male sub-elite judo athletes participated in study 2. Discriminative validity and test-retest reliability of sport-specific parameters (mechanical work, maximal force) were assessed during pulling movements with and without tsukuri (kuzushi). Ecological validity of muscle activity was determined by performing pulling movements using the ergometer without tsukuri and during the same movements against an opponent. In both conditions, electromyographic activity of trunk (e.g., m. erector spinae) and upper limb muscles (e.g., m. biceps brachii) were assessed separately for the lifting and pulling arm. Elite athletes showed mostly better mechanical work, maximal force, and power (0.12 ≤ d ≤ 1.80) compared with sub-elite athletes. The receiver operating characteristic analysis revealed acceptable validity of the JERGo^© system to discriminate athletes of different performance levels predominantly during kuzushi without tsukuri (area under the curve = 0.27-0.90). Moreover, small-to-medium discriminative validity was found to detect meaningful performance changes for mechanical work and maximal force. The JERGo^© system showed small-to-high relative (ICC = 0.37-0.92) and absolute reliability (SEM = 10.8-18.8%). Finally, our analyses revealed acceptable correlations (r = 0.41-0.88) between muscle activity during kuzushi performed with the JERGo^© system compared with a judo opponent. Our findings indicate that the JERGo^© system is a valid and reliable test instrument for the assessment and training of judo-specific pulling kinetics particularly during kuzushi movement without tsukuri.

[Effects of judo-specific resistance training on kinetic and electromyographic parameters of pulling exercises in judo athletes]

BACKGROUND

In judo, rapid force production during pulling movements is an important component of athletic performance, which is why this capacity needs to be specifically exercised in judo. This study aimed at examining the effects of a judo-specific resistance training program using a judo ergometer system (PTJ) versus a traditional resistance training regime using a partner (PTP) on kinetics and muscle activity of judo-specific pulling exercises.

METHOD

Twenty-four male judo athletes (age: 22 ± 4 years, training experience: 15 ± 3 years) were randomly assigned to two groups. In a crossover design, the first group completed a 4-week PTJ followed by four weeks of PTP (each with three sessions per week). The second group conducted PTP prior to PTJ. PTJ and PTP were completed in addition to regular training. Before, 4 weeks and 8 weeks after training, tests were conducted to assess judo-specific pulling kinetics (i. e. maximal force, rate of force development [RFD], mechanical work) and electromyographic (EMG) shoulder/trunk muscle activity (i. e. biceps brachii muscle, deltoid muscle, trapezius muscle, erector spinae muscle) during pulling movements using a judo ergometer as well as unspecific strength tests (i. e. bench-pull, pull-ups).

RESULTS

The statistical analysis revealed that in both groups ergometer pulling kinetics (p <.05, 0.83 ≤d≤ 1.77) and EMG activity (p <.05; 1.07 ≤d≤ 2.25) were significantly enhanced following 8 weeks of training. In addition, significantly larger gains in RFD, mechanical work, and EMG activity (i. e. deltoid muscle, erector spinae muscle, trapezius muscle) were found following PTJ compared to PTP (p <.05, 1.25 ≤d≤ 2.79). No significant enhancements were observed with the unspecific strength tests.

CONCLUSION

Our findings indicate that PTJ is superior to PTP regarding training-induced improvements in force production and muscle activity during judo-specific pulling exercises. Performance enhancements may partly be attributed to neural adaptations. No transfer effects on unspecific strength tests were detected following PTJ and PTP.

Effects of Soccer Training on Anthropometry, Body Composition, and Physical Fitness during a Soccer Season in Female Elite Young Athletes: A Prospective Cohort Study

The objectives of this study were to (i) describe soccer training (e.g., volume, types), anthropometry, body composition, and physical fitness and (ii) compute associations between soccer training data and relative changes of anthropometry, body composition, and physical fitness during a soccer season in female elite young athletes. Seasonal training (i.e., day-to-day training volume/types) as well as variations in anthropometry (e.g., body height/mass), body composition (e.g., lean body/fat mass), and physical fitness (e.g., muscle strength/power, speed, balance) were collected from 17 female elite young soccer players (15.3 ± 0.5 years) over the training periods (i.e., preparation, competition, transition) of a soccer season that resulted in the German championship title in under-17 female soccer. Training volume/types, anthropometrics, body composition, and physical fitness significantly varied over a soccer season. During the two preparation periods, higher volumes in resistance and endurance training were performed (2.00 ≤ d ≤ 18.15; p < 0.05), while higher sprint and tactical training volumes were applied during the two competition periods (2.22 ≤ d ≤ 11.18; p < 0.05). Body height and lean body mass increased over the season (2.50 ≤ d ≤ 3.39; p < 0.01). In terms of physical fitness, significant performance improvements were found over the soccer season in measures of balance, endurance, and sport-specific performance (2.52 ≤ d ≤ 3.95; p < 0.05). In contrast, no statistically significant changes were observed for measures of muscle power/endurance, speed, and change-of-direction speed. Of note, variables of muscle strength (i.e., leg extensors) significantly decreased (d = 2.39; p < 0.01) over the entire season. Our period-specific sub-analyses revealed significant performance improvements during the first round of the season for measures of muscle power/endurance, and balance (0.89 ≤ d ≤ 4.01; p < 0.05). Moreover, change-of-direction speed significantly declined after the first round of the season, i.e., transition period (d = 2.83; p < 0.01). Additionally, significant medium-to-large associations were observed between training and anthropometrics/body composition/physical fitness (−0.541 ≤ r ≤ 0.505). Soccer training and/or growth/maturation contributed to significant variations in anthropometry, body composition, and physical fitness outcomes throughout the different training periods over the course of a soccer season in female elite young soccer players. However, changes in components of fitness were inconsistent (e.g., power, speed, strength). Thus, training volume and/or types should be carefully considered in order to develop power-, speed- or strength-related fitness measures more efficiently throughout the soccer season.