Vertical force production in soccer: mechanical aspects and applied training strategies

Vertical force production (VFP) is widely recognized as a critical determinant of performance in a series of soccer-specific activities, such as sprinting, jumping, and changing direction. Therefore, practitioners are constantly seeking better and more effective strategies to improve VFP in professional soccer players. This article analyzes the mechanical aspects associated with the actual role played by VFP in elite soccer, and also examines and highlights the training considerations related to its appropriate and effective development during modern soccer seasons

A novel approach for athlete profiling: the unilateral dynamic strength index

The dynamic strength index (DSI) provides a ratio of the peak force an athlete can produce in both isometric and ballistic tasks. While the DSI measured during bilateral tests has been examined, unilateral DSI scores have not been reported to date and thus was the aim of the present study. Twenty-eight recreational sport athletes performed three trials of a unilateral isometric squat and countermovement jump (CMJ) to measure peak force in each task across two separate test sessions. The unilateral DSI was calculated using both left vs. right and dominant vs. non-dominant limbs. Good to excellent reliability was shown in the isometric squat (ICC = 0.86-0.96; CV ≤ 5.7%) and the CMJ (ICC = 0.83-0.93; CV ≤ 5.8%) on both limbs. The DSI showed moderate to good reliability (ICC = 0.71-0.79; CV = 7.54-11.9%). DSI scores of 0.52-0.55 and 0.55-0.59 were reported on the left and right limbs respectively, with no significant differences reported between limbs. A significant difference (p = 0.04) was seen for the CMJ between left and right during the second test session only. The dominant and non-dominant limbs reported mean DSI scores of 0.53-0.57, and significant differences were evident between limbs in both the isometric squat and CMJ (p < 0.01). The present study provides normative data for the unilateral DSI and indicates acceptable levels of reliability, while the consistency of individual measures of peak force can be considered good when quantified unilaterally

Practices of strength and conditioning coaches in professional sports: A systematic review

The practices of strength and conditioning (S&C) coaches have been reported in various professional sports. This study aims to comprehensively assess this available evidence to help establish whether theoretical, practical, and evidence-based guidelines align with the practices employed by these experienced S&C coaches. Three databases were searched (PubMed, SPORTDiscus, and Cochrane) until November 2020. Studies surveying the practices of S&C coaches in professional sports using a survey design with common questions, written in English, and published in peer-reviewed journals were reviewed. Eight studies (n= 318 S&C coaches) were finally included. All studies adapted a similar survey, providing a strong basis for comparison between sports. Periodization strategies were widely used (89%), with training volume consistently reduced during the in-season period. Olympic weightlifting was commonly used across sports, except in baseball (29%). Plyometric exercises were predominantly prescribed for speed development (74%) and lower body power (68%), which were mostly programed as complex training (45%) and conducted all year round (52%). Flexibility exercises were mostly performed before practice (83%) for 6–10 min (40%). Physical tests were mainly conducted during the preseason period (66%), with body composition (86%) being the most used test. S&C coaches generally adhered to current guidelines and research in S&C concerning training prescription and physical testing. Whereas, intersport differences were also noted and further discussed. Results of this study can be used by S&C coaches to plan, implement, and review their professional practices. Furthermore, may inform the development of general and sport-specific guidelines, and future research in S&C

Merleau-Ponty dialoga com o Racionalismo e a pintura em “O olho e o espírito”

Em O olho e o espírito (L’oeil et l’esprit), Maurice Merleau-Ponty dialoga com o Grande Racionalismo, principalmente, com Descartes, critica as pretensões ingênuas da ciência do começo do século XX, de reproduzir fenômenos em laboratório, e rende tributo à pintura, essa forma de expressar que mostra à filosofia seu próprio ponto de partida: o vivente no mundo, que conjuga os verbos “eu vejo” com o “eu posso”. Somos, ao mesmo tempo, vidente e visível e nos deslocamos, mesmo que com o olhar; outrossim tocamos e somos tocados num entrelaçamento que forma o quiasma do sensível. E para construir sua ontologia, Merleau-Ponty discorda de todo ponto de vista de sobrevôo, que transforma as coisas em objetos a serem analisados por sujeitos, e valoriza a atividade do pintor que se funde com a pintura ao usar seu corpo para pintar, pois que fornece elementos para sua filosofia em que o vidente não se diferencia do visível, o sujeito do objeto, o eu do mundo. E nesse uso da pintura para expressar sua filosofia, Merleau-Ponty ganha como adepto Gilles Deleuze, crítico da fenomenologia, mas não desse mundo em fusão promovido por suas filosofias e pela pintura.In the Eye and Mind Maurice Merleau-Ponty dialogues with the Great Rationalism, specially with Descartes, criticizes the ingenuous pretensions of the sciences of the early 20th century to reproduce the phenomena in laboratory and pays tribute to the painting, a form of expression that shows to the philosophy its own point of departure: the living in the world, that conjugates the verbs ‘I see’ with ‘I can’. We simultaneously see and are seen and we dislocate ourselves, even if only with the regard; moreover we touch and are touched, forming an interlacing that forms the chiasm of sensibility. In order to construct his ontology, Merleau-Ponty disagrees with every point of view that only overflies, transforming things in objects that ought to be analyzed by subjects. In contrast, he valorizes the painter’s activity, in which the painter, using his own body to paint, fuses himself with the painting. It provides elements to his philosophy, in which that who sees does not differ from that which is seen, nor the subject from the object, nor the ‘I’ from the world. In doing this, MerleauPonty wins as adept Gilles Deleuze, which, although critic of the phenomenology, endorses this amalgamation of painting with philosophy

Comparison of bilateral vs. unilateral-biased strength and power training interventions on measures of physical performance in elite youth soccer players

The aim of the present study was to compare the effects of bilateral and unilateral-biased strength and power training programs on measures of physical performance in male youth soccer players. Twenty-three elite youth players (age: 17.6 1.2 years) were randomly assigned to either a unilateral (n = 11) or a bilateral (n = 12) group, who completed a strength and power intervention, twice per week for 6-weeks. The unilateral group completed rear foot elevated split squats (RFESS), single leg countermovement jumps (SLCMJ), single leg drop jumps (SLDJ) and single leg broad jumps (SLBJ). The bilateral group intervention performed back squats, countermovement jumps (CMJ), drop jumps (DJ) and broad jumps (BJ). A 2 x 2 repeated measures ANOVA showed no between-group differences. However, within-group differences were evident. The bilateral training group showed significant (p < 0.05) improvements in back squat strength (d = 1.27; %Δ = 26.01), RFESS strength (d = 1.64; %Δ = 23.34), BJ (d = 0.76; %Δ = 5.12), 10 m (d = -1.17; %Δ = 4.29) and 30 m (d = -0.88; %Δ = 2.10) performance. The unilateral group showed significant (p < 0.05) improvements in RFESS strength (d = 1.40; %Δ = 33.29), SLCMJ on the left leg (d = 0.76; %Δ = 9.84), SLBJ on the left leg (d = 0.97; %Δ = 6.50), 10 m (d = -1.50; %Δ = 5.20), and 505 on the right leg (d = -0.78; %Δ = 2.80). Standardised mean differences showed that bilateral training favoured improvements in back squat strength and unilateral training favoured improvements in RFESS strength, SLDJ on the right leg and 505 on the right leg. These results show that although both training interventions demonstrated trivial to large improvements in physical performance, the notion of training specificity was evident with unilateral training showing greater improvements in unilateral test measures

Interactive Technology and Gaming to Enhance Understanding in Mathematics

Integrating math and technology has been shown to enhance the educational future of children today. The integration of interactive technology through the use of electronic whiteboards and gaming to enhance student understanding in mathematics was investigated. High school students (N~80) reviewed content through an electronic whiteboard and gaming. It was shown that gaming through the use of electronic whiteboards increased student achievement in mathematics by ensuring a deeper understanding of the material presented

Percentage-based change of direction deficit: a new approach to standardize time- and velocity-derived calculations

Change of direction (COD) efforts are crucial in team-sports and an extensive body of research has been devoted to investigating this complex and multifaceted skill. Most studies have assessed players’ ability to change direction by reporting completion time or average velocity in different COD tasks. However, it has been argued that these variables may not accurately portray an athlete’s true capability to quickly change direction. In this context, new metrics such as the “COD Deficit” (CODD) have been proposed to provide complementary information on the efficiency to change direction. The current literature presents two different CODD computations: time-derived and velocity-derived calculations. Despite both being consistent and representing the same phenomenon, the decision of using one or the other may produce different outcomes, thus influencing coaches’ decisions and training strategies. To overcome this issue, we propose a new approach to the computation of the CODD, based on the difference in percentage between linear sprint and COD abilities, in an attempt to standardize the estimation of this variable and simplify the evaluation of COD performance

Traditional free-weight vs. variable resistance training applied to elite young soccer players during a short preseason: effects on strength, speed, and power performance

Maximizing the neuromuscular capacities of players is a critical challenge during short soccer preseasons. This study compared the effects of two strength-power training regimes, on the strength, speed, and power performance of elite young soccer players during a 4-week preseason. Twenty-five under-20 players from the same club were pair-matched in two training groups as follows: traditional training group (TTG) (n=13), athletes performed half-squat (HS) and jump-squat (JS) exercises as traditionally prescribed; and EB group (EBG) (n=12), athletes performed HS and JS with EB attached to the barbell. Vertical jump height, 20-m sprint velocity, change-of-direction (COD) speed, HS and JS power, and one-repetition maximum (1RM) in the HS were assessed pre, post 2-week, and post 4-week of training. An ANOVA two-way with repeated measures was used to assess the effects of both training protocols over the experimental period. Both strategies were effective for significantly improving HS and JS power (effect sizes [ES] 1.00 - 1.77), HS 1RM (ES = 1.68 and 1.51 for TTG and EBG, respectively), vertical jumping ability (ES 0.37 - 0.65), and COD speed (ES = 0.81 and 0.39 for TTG and EBG, respectively), when comparing pre- and post-measures. In contrast, both TTG and EBG failed to increase 20-m sprint velocity (ES ranging between -0.54 and 0.23). In conclusion, both training schemes were able to improve the strength and power performance, but not the sprint capacity of young soccer players. To accelerate strength gains over very-short time periods (i.e., 2-week), variable resistance training may be advantageous. Conversely, to optimize power adaptations in ballistic exercises across a similar time period, traditional FW training may be preferred

Maximum strength, relative strength, and strength deficit: relationships with performance and differences between elite sprinters and professional rugby union players

Purpose: To test the relationships between maximum and relative strength (MS and RS), absolute and relative peak force (PF and RPF), and strength deficit (SDef), with sprint and jump performance, and to compare these mechanical variables between elite sprinters and professional rugby union players. Methods: Thirty-five male rugby union players and thirty male sprinters performed vertical jumps, 30-m sprint, and the half-squat one-repetition maximum (1RM) assessment, where these force-related parameters were collected. Pearson correlation coefficient was used to test the relationships among the variables. An independent t-test and magnitude-based inferences compared the mechanical variables between sprinters and rugby players. Results: Almost certain significant differences were observed for jump and sprint performance between the groups (P < 0.0001). Rugby union players demonstrated a likely significant higher MS (P = 0.03), but a very likely lower RS (P = 0.007) than sprinters. No significant differences were observed for PF between them. Sprinters exhibited an almost certain significant higher RPF than rugby players (P < 0.0001). Furthermore, rugby players demonstrated almost certain to likely significant higher SDef from 40 to 70% 1RM (P < 0.05) compared to sprinters. Overall, all strength-derived parameters were significantly related to functional performance. Conclusions: Elite sprinters present higher levels of RS and RPF, lower levels of SDef, and superior sprint and jump performance than professional rugby players. Relative strength-derived values (RS and RPF) and SDef are significantly associated with speed-power measures and may be used as effective and practical indicators of athletic performance