Classification of Soccer and Basketball Players' Jumping Performance Characteristics: A Logistic Regression Approach

Effects of a Strength and Conditioning Offseason Program on Countermovement Jump Ground Reaction Forces in Division I American Football Players

ABSTRACT

Gillen, ZM, Burch, RF, Saucier, DN, Strawderman, L, Luczak, T, Piroli, A, Petway, AJ, and Rath, T. Effects of a strength and conditioning offseason program on countermovement jump ground reaction forces in Division I American football players. J Strength Cond Res 38(3): e86-e95, 2024-The purpose of this study was to examine the effects of a 10-week strength and conditioning offseason program on the ground reaction forces (GRFs) of American football players during single-leg and double-leg countermovement jumps (SLJ and CMJ, respectively). Each subject visited the laboratory twice, once for preoffseason and once for postoffseason testing. During each visit, subjects performed CMJs and SLJs for each leg. Ground reaction forces were collected by force plates to quantify unweighting, braking, propulsive, and performance metrics for each jump. In addition, an efficiency index was calculated for each jump to examine changes in vertical jump efficiency. Dependent samples t tests compared all CMJ metrics. Two-way repeated measures analyses of variance (leg × time) compared all SLJ metrics. An alpha level of p ≤ 0.05 was considered statistically significant. For the CMJ, propulsive phase duration decreased due to the program ( p = 0.007), whereas peak braking power, peak propulsive power, mean propulsive force, and jump height increased ( p ≤ 0.012). For the SLJ, peak braking power, force at the low position, braking rate of force development, eccentric force, peak propulsive power, mean propulsive force, and jump height increased in both legs ( p ≤ 0.044). The efficiency index increased for the CMJ and the SLJ for both legs ( p ≤ 0.016). This study demonstrated that SLJ and CMJ vertical jump performance significantly increases in as few as 10 weeks of offseason strength and conditioning. Strength and conditioning programming may effectively increase vertical jump performance, as assessed by GRFs, which can be used as a simple indicator regarding changes in athletic performance.

Beyond Belief: Exploring the Alignment of Self-Efficacy, Self-Prediction, Self-Perception, and Actual Performance Measurement in a Squat Jump Performance-A Pilot Study

It is widely accepted that athletic performance emerges from a complex interaction between physical and cognitive features. Several studies highlighted self-efficacy (SE) in the cognitive domain of athletic performance, but no studies have correlated SE with sport-specific tasks. According to Bandura, this study explored SE and its relationship with self-prediction (SP), self-perception (PSJ), and actual performance in a squat jump (SJ). Thirty-nine healthy collegiate students were assessed using an SE questionnaire, an SP measurement tool, and a validated optical system for actual SJ performance. An SE score and an SE esteem index (SEE) were determined. The alignment between an individual's SP of their SJ performance and their SE beliefs was also examined. The data revealed a significant correlation between SE score and both SJ (r = 0.432; p = 0.006) and SP (r = 0.441; p = 0.005). Furthermore, disparities among the actual SJ, SP, and SEE were statistically non-significant, implying a congruence between self-belief and performance. With a deeper understanding of the interaction between SE, SP, and sport-specific tasks, sports professionals could develop targeted interventions to enhance athletes' overall athletic achievements and apply SE as a feature linking physical and cognitive athletic performance.

Pivot Step Jump: A New Test for Evaluating Jumping Ability in Young Basketball Players

Jumping ability in basketball is usually assessed using standardized vertical jump tests. However, they lack specificity and do not consider the player’s basketball skills. Several studies have suggested performing specific jump tests, which are tailored to the movement patterns and requirements of a basketball game. The pivot step jump test (PSJT) is a novel test designed to evaluate the specific jumping abilities of basketball players by combining a pivot step on one leg with a maximum bilateral vertical jump. This study had two aims: to determine the reliability and validity of the PSJT using typical jump tests as the criterion measure and to demonstrate the PSJT as a practical test to evaluate specific jumping ability in young male and female basketball players. Twenty female (EGA; 14.0 ± 0.7 years, 59.3 ± 7.9 kg, 162.1 ± 5.5 cm) and fifteen male (EGB; 14.0 ± 0.7 years, 58.1 ± 7.7 kg, 170.3 ± 6.4 cm) basketball players participated in the study. The test−retest reliability of the PSJT within sessions (intrasession reliability) and across sessions (intersession reliability) was assessed within EGA. For the evaluation of validity, EGB performed the PSJT and a series of criterion jumping tests. For EGA, no changes (p > 0.05) were found in PSJT performance between test sessions and excellent intra- and intersession reliability was observed (ICCs > 0.75). Correlation coefficients indicated high factorial validity between the jumping tests and PSJT (r = 0.71−0.91, p < 0.001). The PSJT appears to offer a valid assessment of jumping ability in basketball and is a practical test for assessing sport-specific jumping skills in young basketball players.

Predictive Value of Repeated Jump Testing on Nomination Status in Professional and under 19 Soccer Players

Soccer clubs invest time and money in multidimensional identification practices, but the field implementation is still problematic. The repeated vertical jump test (RVJ), as an alternative to the monodimensional vertical jump, may offer similar prognostic value. Therefore, the prognostic validity of 15 RVJ within professional (PRO, n = 24) and under 19 years old (U19, n = 20) Greek male soccer players was examined. T-test, binomial logistic regression, and receiver operating characteristic for prognostic validity of anthropometric and performance values in predicting PRO status were applied using Jamovi version 2.3.3.0. Significant group differences presented in body height and mass, body mass index (BMI), maximum and average jump height, and relative jump power. The predicting model was significant (x²(2) = 17.12, p < 0.001). Height and BMI were positive predictors of the PRO status (b = 21.66, p = 0.008 and b = 0.94, p = 0.014, respectively). The model was 73% accurate, 75% specific, and 71% sensitive, with excellent area under the curve. The RVJ test demonstrated outstanding discriminating prognostic validity. Until the applicability of the multidimensional models in predicting future player status is further established, field practitioners may use the simplistic RVJ testing to predict future status among male soccer players.

DNN-based multi-output model for predicting soccer team tactics

In modern sports, strategy and tactics are important in determining the game outcome. However, many coaches still base their game tactics on experience and intuition. The aim of this study is to predict tactics such as formations, game styles, and game outcome based on soccer dataset. In this paper, we propose to use Deep Neural Networks (DNN) based on Multi-Layer Perceptron (MLP) and feature engineering to predict the soccer tactics of teams. Previous works adopt simple machine learning techniques, such as Support Vector Machine (SVM) and decision tree, to analyze soccer dataset. However, these often have limitations in predicting tactics using soccer dataset. In this study, we use feature selection, clustering techniques for the segmented positions and Multi-Output model for Soccer (MOS) based on DNN, wide inputs and residual connections. Feature selection selects important features among features of soccer player dataset. Each position is segmented by applying clustering to the selected features. The segmented positions and game appearance dataset are used as training dataset for the proposed model. Our model predicts the core of soccer tactics: formation, game style and game outcome. And, we use wide inputs and embedding layers to learn sparse, specific rules of soccer dataset, and use residual connections to learn additional information. MLP layers help the model to generalize features of soccer dataset. Experimental results demonstrate the superiority of the proposed model, which obtain significant improvements comparing to baseline models.

The Osgood-Schlatter disease: a large clinical series with evaluation of risk factors, natural course, and outcomes

PURPOSE

The aims of this prospective study were to define sport specific incidence rates in a large Osgood-Schlatter-disease group, to follow the natural course, and to determine late effects, i.e., changes in sport activities and resting pain.

METHODS

A total of 126 consecutive patients with functional pain in and after physical activity and local TT swelling were included in a longitudinal study. Physical examination, ultrasound, and a lateral X-ray were performed in a standardized clinically common manner. Sport participation, growth rate, BMI, and muscle status were recorded and assigned statistically. Follow-up took place after subsidence of functional pain.

RESULTS

Exactly 101 boys and 25 girls showed a mean age at diagnosis of 12.8 years (boys 13.2, girls 11.4 years) complaining an average period of pain of 6.7 months before diagnosis. A sport distribution displayed 64 football (soccer) players, 18 basketball players, seven athletes in track and field, six martial arts sportsmen, and five handball players, all participating in organized sport clubs, 16 patients in other and ten patients in no sports. The standing leg was affected in 69.6% of all football players, whereas the other disciplines did not show any significance. A total of 105 patients could be followed up after a median of 3.6 years; six of them were still symptomatic. Final outcome could be recorded for 99 patients (79 boys, 20 girls). Osgood-Schlatter disease (OSD) symptoms in or after sport activity were reported to last an average of 19.1 months (3-48 months) without differences according to sex nor sport. Exactly 50% of the patients may expect to be free of functional symptoms after the 16th month, 75% after the 25th month. A total of 78.8% of the patients still complained of persistent but not impairing pain in kneeling or on direct TT contact. Exactly 28.3% of all patients responded having switched their sport activity to other disciplines due to OSD.

CONCLUSION

OSD affects mainly adolescent boys active in football and basketball and represents a structural answer to repeated biomechanical stress. Only in football, the statically dominant side is more prone to develop OSD. Age at onset, growth rate, BMI, and muscle imbalance are not significantly predisposing. OSD runs a self-limiting course without specific treatment.

Phase-Specific Force and Time Predictors of Standing Long Jump Distance

This study sought to identify potential predictors of standing long jump (SLJ) performance using force-time strategy metrics within the unloading, eccentric yielding, eccentric braking, and concentric phases. Fifteen National Collegiate Athletic Association division 1 male soccer players (19 [1] y, 1.81 [0.94] m, 80.3 [22.4] kg) performed 3 maximum-effort SLJs, while 3-dimensional ground reaction force (GRF) data were obtained. Regularized regression models were used to investigate associations between force-time strategy metrics and 2 metrics of SLJ performance (ie, jump distance and modified reactive strength index). Jump height and eccentric yielding time were the only predictors of jump distance that also demonstrated large correlations to jump distance. Anterior-posterior unloading yank, average concentric vertical force, and concentric phase duration were the only predictors of modified reactive strength index that also demonstrated large correlations to modified reactive strength index. To maximize SLJ distance in high-level soccer athletes, human performance practitioners could design interventions to drive changes in strategy to increase jump height and decrease eccentric yielding time. To improve SLJ explosiveness, interventions to drive changes in unloading and concentric force application and decrease concentric time could be emphasized. Importantly, unique variable combinations can be targeted when training for SLJ distance and explosiveness adaptations.

Comparison of multidirectional jump performance and lower limb passive range of motion profile between soccer and basketball young players

This study was performed aimed at comparing multidirectional bilateral and unilateral jump performance and passive range of motion (ROM) of lower limbs between soccer and basketball young players and evaluating associations between inter-limb ROM asymmetry and bilateral jump performance. A total of 67 young male athletes participated in this study, who were classified as soccer (n = 40; 15.55 ± 1.5 y; 1.76 ± 0.12 m; 58.15 ± 10.82 kg; 19.84 ± 2.98 kg·m2) and basketball (n = 27; 15.7 ± 1.66 y; 1.76 ± 0.12 m; 62.33 ± 16.57 kg; 19.84 ± 2.98 kg·m2) players. Participants were asked to perform bilateral and unilateral multidirectional jumps, and passive ROM of hip (flexion, extension and abduction), knee (flexion) and ankle (dorsiflexion) joints was also assessed. Significant between-group differences were observed for hip extension with flexed knee ROM in dominant (soccer: 142.43 ± 7.74°; basketball: 148.63 ± 8.10°) and non-dominant (soccer: 144.38 ± 8.36°; basketball: 148.63 ± 6.45°) legs; hip flexion with flexed knee ROM in dominant (soccer: 13.26 ± 4.71°; basketball: 9.96 ± 3.42°) and non-dominant (soccer: 12.86 ± 4.55°; basketball: 9.70 ± 3.62°) legs; and for the ratio of hip abduction (soccer: 1.02 ± 0.08; basketball: 0.97 ± 0.11). However, no significant between-group differences were observed for bilateral and unilateral jump capacity, or for inter-limb asymmetries (dominant vs. non-dominant leg). Finally, no associations were observed between ROM ratio (dominant vs. non-dominant leg) and bilateral jump performance. These findings lead to the suggestion that differences on passive ROM values in young male athletes may be sport-specific. Additionally, there seems to be need for the implementation of training strategies specifically aimed at improving bilateral or unilateral jump ability, or at diminishing inter limb passive ROM differences in order to improve multidirectional jump performance for neither soccer nor basketball youth male players.

Can Countermovement Jump Neuromuscular Performance Qualities Differentiate Maximal Horizontal Deceleration Ability in Team Sport Athletes?

This investigation aimed to determine the countermovement jump (CMJ) neuromuscular performance (NMP) qualities that differentiate between athletes with high or low horizontal deceleration ability. Twenty-seven male university team sport athletes performed a CMJ on vertical axis force plates and a maximal horizontal deceleration following a 20 m maximal horizontal sprint acceleration. The instantaneous velocity throughout the maximal horizontal deceleration test was measured using a radar device. The deceleration ability was evaluated using the average deceleration (HDEC, m·s-2) and change in momentum-referred to as the horizontal braking impulse (HBI, N·s·kg-1). Participants were dichotomised into high and low HDEC and HBI according to a median-split analysis, and CMJ variables calculated for the overall eccentric, eccentric-deceleration and concentric phases. When horizontal deceleration ability was defined by HDEC, the CMJ concentric (effect size (ES) = 0.95) and eccentric (ES = 0.72) peak forces were the variables with the largest difference between groups. However, when defined using HBI, the largest difference was the concentric (ES = 1.15) and eccentric (ES = -1.00) peak velocities. Only the concentric mean power was significantly different between the high and low groups for both HDEC (ES = 0.85) and HBI (ES = 0.96). These findings show that specific eccentric and concentric NMP qualities may underpin the horizontal deceleration abilities characterised by HDEC and HBI. Specific NMP training interventions may be beneficial to target improvements in either of these measures of horizontal deceleration abilities.