The Qatar 2022 World Cup warm-up: Football goal-scoring evolution in the last 14 FIFA World Cups (1966-2018).

The aim of this study was to elucidate pattern of attacking actions leading up to goal scoring during the 14 FIFA World Cups from 1966 to 2018. The study analysed 1881 goals scored during a total of 732 matches. We employed observational methodology design. Before goal analysis began, it was developed the observing protocol in which data related to selected variables, by system of notation, was entered after reviewing each individual goal scoring action. The analysis of all video material was carried out independently by four experienced examiners (three of them are Ph.D in sports science and one is Ph.D. candidate in sports science with at least 7 years of coaching and experience as analyst in football). The inter-and intra-observer reliability presented good level of agreement. The kappa values ranged from 0.82 (goal scoring through open play) to 1.00 (action leading up to goal), showing a very high agreement for all performance variables. Interclass correlation was very high (ICC = 0.966, 95% upper and lower confidence intervals were between 0.933 and 1.00). A statistically significant trend (p < 0.05) from 1966 to 2018 was identified towards a higher relative frequency of goals scored from set play and collective actions from open play. The Chi-square did not reveal significant differences in the frequency of goal scoring patterns and goal-scoring zones. The results also revealed that the majority of goals were scored between the 76th and 90th minutes of a match (22.7%), from open play (70.5%), inside the penalty area (54.7%), one touch finishing (62.5%), and collective attacks in open play (55.8%). These findings may provide a possible strategic direction for improving goal-scoring performance in football, as well as practical implementation in World Cup tournament preparation.

Reliability and Sensitivity of Reaction Time Measurements During Quasi-Realistic Soccer Situations.

Reliability and sensitivity of reaction time (RT) during quasi-realistic soccer situations was explored in 10 professional soccer players (skilled; age = 20.9 ± 3.6 years) and 10 males without soccer experience (nonskilled; age = 23.4 ± 0.5 years). The participants were instructed to react as fast as possible to a stimulus presented via the video-based method while standing on force platforms. RT was computed as the difference between the instant when the rate of force development of any leg reaches 5% of its maximal value and the instant of stimulus presentation. The results revealed acceptable to high reliability of RT (intraclass correlation coefficient median = .90; coefficient of variation ≤ 5.83%), and shorter RT for skilled compared with nonskilled participants in three out of eight comparisons (effect size range = 1.00-1.41). The video-based methods can be confidently used to assess the RT in soccer players.

Is Test Standardization Important when Arm and Leg Muscle Mechanical Properties are Assessed through the Force-Velocity Relationship?

The force-velocity (F-V) relationship observed in multi-joint tasks proved to be strong and approximately linear. Recent studies showed that mechanical properties of muscles: force (F), velocity (V) and power (P) could be assessed through the F-V relationship although the testing methods have not been standardized. The aim of the present study was to evaluate and compare F-V relationships assessed from two tests performed on a modified Smith machine that standardizes kinematics of the movement pattern. Fifteen participants were tested on the maximum performance bench press throws and squat jumps performed against a variety of different loads. In addition, their strength properties were assessed through maximum isometric force (Fiso) and one repetition maximum (1 RM). The observed individual F-V relationships were exceptionally strong and approximately linear (r = 0.98 for bench press throws; r = 0.99 for squat jumps). F-V relationship parameter depicting maximum force (F0) revealed high correlations with both Fiso and 1 RM indicating high concurrent validity (p < 0.01). However, the generalizability of F-V relationship parameters depicting maximum force (F0), velocity (V0) and power (P0) of the tested muscle groups was inconsistent and on average low (i.e. F0; r = -0.24) to moderate (i.e. V0 and P0; r = 0.54 and r = 0.64, respectively; both p < 0.05). We concluded that the F-V relationship could be used for the assessment of arm and leg muscle mechanical properties when standard tests are applied, since the typical outcome is an exceptionally strong and linear F-V relationship, as well as high concurrent validity of its parameters. However, muscle mechanical properties could be only partially generalized across different tests and muscles.

Effects of loading on maximum vertical jumps: Selective effects of weight and inertia.

A novel loading method was applied to explore selective effects of externally added weight (W), weight and inertia (W+I), and inertia (I) on maximum counter-movement jumps (CMJ) performed with arm swing. Externally applied extended rubber bands and/or loaded vest added W, W+I, and I corresponding to 10-40% of subjects' body mass. As expected, an increase in magnitude of all types of load was associated with an increase in ground reaction forces (GRF), as well as with a decrease in both the jumping performance and power output. However, of more importance could be that discernible differences among the effects of W, W+I, and I were recorded despite a relatively narrow loading range. In particular, an increase in W was associated with the minimal changes in movement kinematic pattern and smallest reduction of jumping performance, while also allowing for the highest power output. Conversely, W+I was associated with the highest ground reaction forces. Finally, the lowest maxima of GRF and power were associated with I. Although further research is apparently needed, the obtained finding could be of potential importance not only for understanding fundamental properties of the neuromuscular system, but also for optimization of loading in standard athletic training and rehabilitation procedures.