Effect of 3 vs. 3 Soccer Small-Sided Game on Various Performance, Inflammatory, Muscle Damage and Hormonal Indicators in Semi-Professional Players.

The purpose of this study was to examine the effect of a soccer small-sided game (SSG) on performance, inflammatory, muscle damage and hormonal indicators. Twenty-two male soccer players participated and were assigned to either experimental (EXP = 12) or control (CON = 10) groups. Subjective fatigue (RPE) and lactate (La¯) were measured during the SSG; vertical squat jump (SJ), 20-m sprint, creatine kinase (CK), interleukin-6 (IL-6), cortisol (C), and testosterone (T) were measured before (PRE), after (POST), 24 h, 48 h, and 72 h after the SSG in the EXP group. The heart rate during the SSG reached 92 ± 3% of their HRmax, whereas La¯ and RPE reached 13.02 ± 1.60 mmol·L−1 and 15 ± 1 after SSG, respectively. The IL-6, different among measurements (F (1.04, 11.50) = 504.82, p < 0.001), peaked (3.52 ± 0.43 pg·mL−1 [95%CI; 3.28−3.77]) after the SSG and returned to baseline 24 h later. The CK, different among measurements (F (1.76, 19.32) = 93.96, p < 0.001), peaked (536.58 ± 124.73U·L−1 [95%CI; 466.01−607.15]) 24 h after the SSG and remained significantly higher than PRE condition in POST and up to 72 h later. The T/C ratio, significantly different among measurements (F (1.73, 19.05) = 12.12, p < 0.001), was at its lowest (0.44 ± 0.16 [95%CI; 0.35−0.54]) immediately after the SSG (p < 0.05) and returned to baseline after 24 h. It seems that 48 h (at the most) after an SSG is adequate time for players to recover, and a high training load should be avoided sooner than 24 h after an SSG.

Effects of a Futsal Game on Metabolic, Hormonal, and Muscle Damage Indicators of Male Futsal Players.

ABSTRACT: Bekris, E, Gioldasis, A, Gissis, I, Katis, A, Mitrousis, I, and Mylonis, E. Effects of a futsal game on metabolic, hormonal and muscle damage indicators of male futsal players. J Strength Cond Res 36(2): 545-550, 2022-The aim of this study was to examine the effects of a futsal game on several metabolic, hormonal, and muscle damage indicators. Twenty-one male top-level futsal players participated in the study. Players were divided into 2 groups according to playing time: the long playing time (LPT) group and the short playing time (SPT) group. Game intensity parameters such as percentage of the HRmax and blood lactate concentration, as well as metabolic, hormonal, and muscle damage indicators were examined before and after a futsal game. The results showed that during the game, the intensity was up to 93% of HRmax and lactate concentrations ranged from 5.8 to 21.8 mmol·L-1. The LPT group showed an increased lactate dehydrogenase level compared with the SPT group (p < 0.05). Similarly, creatine kinase was significantly increased in the LPT group (p < 0.05) after the game. By contrast, nonsignificant differences were observed between groups for alanine transaminase (ALT-SGPT), aspartate transaminase (AST-SGOT), and gamma-glutamyl transferase enzymes (p > 0.05). The testosterone/cortisol ratio (T/C) reduced for both groups after the game (p < 0.05). The results of this study indicated that a futsal game have a significantly effect on several hormonal, metabolic, and muscle damage indicators for players who participate for a longer playing time in the game. Therefore, the evaluation of these volumes could assist coaches to organize specific, effective, and individualized training programs.

Sprinting and dribbling differences in young soccer players: a kinematic approach.

Sprinting and dribbling a ball are considered essential for success in team sports, such as soccer. The purpose of the present study was to examine straight line (SL) and changes of direction (COD) sprinting and dribbling abilities after a standing and a flying starting position. Twelve amateur U12 male soccer players participated in the study. The participants were tested in four different sprinting conditions. The first consisted of 15 m SL sprinting and dribbling test by standing position; the second consisted of 15 m SL sprinting and dribbling test by flying start. The third condition consisted of 15 m COD sprinting and dribbling test by standing position, and the fourth condition consisted of 15 m COD sprinting and dribbling test by flying start. T-tests analysis indicated significant differences between SL sprinting and dribbling sprinting tests (P < 0.05) and between standing and flying start positions (P < 0.05). Step frequency was higher for sprinting tests (P < 0.05). Moreover, the results showed that step length was longer when players had a standing position (P < 0.05). These findings emphasize the importance for trainers to add parts without ball, focused on the development of certain fitness and running components.

Examination of Physical Fitness Parameters Between Professional and Amateur Greek Soccer Players During the Transition Period.

ABSTRACT: Bekris, E, Pidoulas, G, Pidoulas, P, Gissis, I, Katis, A, and Komsis, S. Examination of physical fitness parameters between professional and amateur Greek soccer players during the transition period. J Strength Cond Res 35(3): 776-781, 2021-The aim of the study was to compare physical fitness parameters between professional and amateur soccer players of different levels. The sample consisted of 381 soccer players divided in 4 experimental groups: first division professional players (n = 115), second division professional players (n = 70), third division semiprofessional players (n = 93), and amateur soccer players (n = 103). Players were tested for several physiological parameters at the end of the transition period. Analysis of variance showed significantly lower body fat and increased maximum oxygen consumption (V̇o2max) and velocity of maximum oxygen consumption (vV̇o2max) values for first division professional players compared with the other experimental groups (p < 0.05). Similarly, first division professional players showed higher performance during squat jump and countermovement jump test compared with the other experimental groups (p < 0.05). Significant differences on flexibility test were observed between amateur players and the other group (p < 0.05). The results of the study indicated that Greek soccer players at the highest level overcome in almost all the underexamination physiological parameters probably because of less absence from training and better implementation of training programs during the transition period.

Evaluation of ball passing and space detection skill in soccer: implementation of two new soccer tests.

The present study examined the validity and reliability of two new soccer tests: the Passing Accuracy Test (PAT), which assesses ball passing accuracy in combination with visual stimulus recognition and the Passing and Visual Recognition test (PVR), which assesses player's space detection skill in a 360 degrees range along with the frequency and the accuracy of ball passing technique. Participants were allocated in four (4) groups based on their age: the Under 11 (U11) group consisted of 101 players, the Under 14 (U14) group consisted of 100 players, the Under 17 (U17) group consisted of 118 players and the Adults (AD) group consisted of 43 players. The typical error, the limits of agreement and the ICC of PAT and PVR test were examined. The results of the study showed high validity and reliability for both tests with the exception in PAT for adult group (ICC = 0.33-0.83; P < 0.05). Therefore, both tests could be valuable tools to assess the accuracy of ball passing technique and the space detection skill in players of different ages.

Variation of aerobic performance indices of professional elite soccer players during the annual macrocycle.

BACKGROUND: The purpose of the present study was to examine the variation of aerobic performance parameters of elite Greek soccer players. METHODS: In the study participated twenty-four (24) male professional soccer players (age: 24.3±4.3 years, height: 180.3±3.8 cm and mass: 77.4±6.1 kg), who competed at the top level of the Greek National Championship. Four measurements regarding aerobic parameters were conducted during the annual training cycle (preseason, start of the season, end of the first championship round and end of the season). RESULTS: The ANOVA analysis showed that maximum oxygen uptake (VO2max) was significantly increased after the completion of the preseason and continued to increase until the end of the first round of the Championship. In contrast, a decline was observed towards the end of the season. The velocity to maximum oxygen uptake (vVO2max) and the velocity parameter in respiratory threshold were significantly increased at the end of the preseason and the end of the first round, while the parameters were differentiated at the end of the season. The lactate concentration showed no significant changes during the four measurements. CONCLUSIONS: A systematic observation of players' performance, especially recording parameters such as VO2max, during the annual training cycle, could provide the necessary feedback for both trainers and players in order to increase team performance.

Age and gender differences in kinematics of powerful instep kicks in soccer.

Soccer kicking training should be adjusted to the characteristics of the athletes. Therefore, examination of differences in kicking kinematics of females and pubertal players relative to males is worthwhile. The purpose of the study was to compare kicking kinematics and segmental sequence parameters between male, female, and pubertal players. Ten adult male, ten adult female, and ten male pubertal players participated in the study. Participants performed five consecutive kicking trials of a stationary ball, as powerful as they could. Analysis of variance showed significantly higher ball velocity, higher joint linear velocities for the knee and the hip, and higher angular velocities of the knee and the ankle for males compared to female and pubertal players (p < 0.05). Similarly, the peak joint velocity was achieved significantly closer to ball impact in males compared to other groups (p < 0.05). Males also showed a more plantarflexed ankle immediately before ball impact (p < 0.05). Females and pubertal players may benefit from skill training aiming to increase ankle plantarflexion and hip flexion prior to ball impact, and to adjust thigh and shank motion, such that the shank-foot segment travels through a higher range of motion and with a greater velocity.

Recovery of powerful kick biomechanics after intense running fatigue in male and female soccer players.

BACKGROUND: Fatigue seems to have a significant effect on soccer kick performance. However, the duration of these effects has not been previously investigated. OBJECTIVES: The purpose of the present study was to investigate the duration of the acute effects of fatigue on soccer kick performance in males and females. PATIENTS AND METHODS: Ten male (age: 26.3 ± 4.9 years, height: 178.1 ± 5.1 cm, mass: 81.3 ± 8.1 kg) and ten female (age: 24.4 ± 4.2 years, height: 169.7 ± 5.7 cm, mass: 61.8 ± 5.1 kg) amateur soccer players performed three instep kicks prior to and after running on a treadmill till exhaustion. Three-dimensional kinematics were collected pre- and post-fatigue. RESULTS: Analysis of variance indicated a statistically significant decline in ball speed during the first and the second trial after fatigue (P < 0.05), but recovered to pre-fatigue levels during the third post-fatigue kicking trial (P > 0.05). Similarly, maximum ankle, knee and hip linear velocity and ankle angular displacement were significantly lower during the first two trials (P < 0.05), but not during the third trial after fatigue (P > 0.05). CONCLUSIONS: Soccer kick parameters recovered to pre-fatigue levels approximately within a minute after the end of the protocol. These findings have a practical meaning for players who have to perform set piece kicks under fatigue conditions and for coaches who have to guide their players.

Effects of a 10-week resistance exercise program on soccer kick biomechanics and muscle strength.

The purpose of the study was to examine the effects of a resistance exercise program on soccer kick biomechanics. Twenty male amateur soccer players were divided in the experimental group (EG) and the control group (CG), each consisting of 10 players. The EG followed a 10-week resistance exercise program mainly for the lower limb muscles. Maximal instep kick kinematics, electromyography, and ground reaction forces (GRFs) as well as maximum isometric leg strength were recorded before and after training. A 2-way analysis of variance showed significantly higher ball speed values only for the EG (26.14 ± 1.17 m·s vs. 27.59 ± 1.49 m·s before and after training, respectively), whereas no significant differences were observed for the CG. The EG showed a decline in joint angular velocities and an increase in biceps femoris electromyography of the swinging leg during the backswing phase followed by a significant increase in segmental and joint velocities and muscle activation of the same leg during the forward swing phase (p < 0.05). The EG also showed significantly higher vertical GRFs and rectus femoris and gastrocnemius activation of the support leg (p < 0.05). Similarly, maximum and explosive isometric force significantly increased after training only for the EG (p < 0.05). These results suggest that increases in soccer kicking performance after a 10-week resistance training program were accompanied by increases in maximum strength and an altered soccer kick movement pattern, characterized by a more explosive backward-forward swinging movement and higher muscle activation during the final kicking phase.

Mechanisms that influence accuracy of the soccer kick.

Goal scoring represents the ultimate purpose of soccer and this is achieved when players perform accurate kicks. The purpose of the present study was to compare accurate and inaccurate soccer kicks aiming to top and bottom targets. Twenty-one soccer players performed consecutive kicks against top and bottom targets (0.5m(2)) placed in the center of the goal. The kicking trials were categorized as accurate or inaccurate. The activation of tibialis anterior (TA), rectus femoris (RF), biceps femoris (BF) and gastrocnemius muscle (GAS) of the swinging leg and the ground reaction forces (GRFs) of the support leg were analyzed. The GRFs did not differ between kicking conditions (P > 0.05). There was significantly higher TA and BF and lower GAS EMG activity during accurate kicks to the top target (P < 0.05) compared with inaccurate kicks. Furthermore, there was a significantly lower TA and RF activation during accurate kicks against the bottom target (P < 0.05) compared with inaccurate kicks. Enhancing muscle activation of the TA and BF and reducing GAS activation may assist players to kick accurately against top targets. In contrast, players who display higher TA and RF activation may be less accurate against a bottom target. It was concluded that muscle activation of the kicking leg represents a significant mechanism which largely contributes to soccer kick accuracy.

Differences in soccer kick kinematics between blind players and controls.

The purpose of the current study was to examine the kinematic differences during instep soccer kicks between players who were blind and sighted controls. Eleven male soccer players who were blind and nine male sighted performed instep kicks under static and dynamic conditions. The results indicated significantly higher (p < .05) ball speed velocities (20.81m/sec) and ball/foot speed ratio values (1.35) for soccer players who were blind during the static kick compared with sighted players (16.16m/sec and 1.23, respectively). Significant group effect on shank and foot angular velocity was observed during the static kicking condition (p < .05), while no differences were found during the dynamic kicking condition (p > .05). Despite the absence of vision, systematic training could have beneficial effects on technical skills, allowing athletes who are blind to develop skill levels comparable to sighted athletes.

Is soccer kick performance better after a "faking" (cutting) maneuver task?

Cutting in soccer is a common skill used to avoid the opponent's pressure but the potential effects of such a skill on instep kicking performance have not been previously investigated. The purpose of this study was to examine the differences in lower limb biomechanics between straight approach soccer kicks and kicks performed following a cutting maneuver task. Ten young amateur soccer players performed, in a random order, instep kicks after a two-step straight approach run and kicks after a double "faking" cutting maneuver task. The results showed that kicking after a cutting maneuver task displayed significantly lower ball speed values compared with the straight approach instep kicking (16.73 vs. 19.78 m/s, respectively; p < 0.05). Moreover, analysis of variance showed significant differences between the two kicking conditions in ankle, knee and hip joint displacements. The present study indicated that performing instep kicks after a double-cutting maneuver reduces ball and foot speed probably due to increasing joint frontal and transverse plane rotations. Improvements in the performance of the cutting maneuver task through training might result in better transfer of energy and speed to the kicking task thus permitting players to perform more powerful kicks under realistic game conditions.

Three-dimensional kinematics and ground reaction forces during the instep and outstep soccer kicks in pubertal players.

The purpose of the present study was to compare the three-dimensional kinematics of the lower extremities and ground reaction forces between the instep kick and the kick with the outside area of the foot (outstep kick) in pubertal soccer players. Ten pubertal soccer players performed consecutive kicking trials in random order after a two-step angled approach with the instep and the outstep portion of the foot. Three-dimensional data and ground reaction forces were measured during kicking. Paired t-tests indicated significantly higher (P < 0.05) ball speeds and ball/foot speed ratios for the instep kick compared with the outstep kick. Non-significant differences in angular and linear sagittal plane kinematic parameters, temporal characteristics, and ground reaction forces between the instep and outstep soccer kicks were observed (P > 0.05). In contrast, analysis of variance indicated that the outstep kick displayed higher hip internal rotation and abduction, knee internal rotation, and ankle inversion than the instep kick (P < 0.05). Our results suggest that the instep kick is more powerful than the outstep kick and that different types of kick require different types of skill training.

Effects of small-sided games on physical conditioning and performance in young soccer players.

The purpose of this study was to examine, first, the movement actions performed during two different small-sided games and, second, their effects on a series of field endurance and technical tests. Thirty-four young soccer players (age: 13 ± 0.9 yrs; body mass: 62.3 ± 15.1 kg; height: 1.65 ± 0.06 m) participated in the study. Small-sided games included three-a-side (3 versus 3 players) and six-a-side (6 versus 6 players) games consisting of 10 bouts of 4 min duration with 3 min active recovery between bouts. Soccer player performance was evaluated using five field tests: a) 30m sprint, b) throw-in for distance, c) Illinois Agility Test, d) dribbling the ball and e) horizontal jump before, in the middle and after the implementation of both game situations. Heart rate was monitored during the entire testing session. Each game was also filmed to measure soccer movements within the game. The ANOVA analysis indicated that the three-a- side games displayed significantly higher heart rate values compared with the six-a-side games (p < 0.05). The number of short passes, kicks, tackles, dribbles and scoring goals were significantly higher during the three-a-side compared with the six-a-side game condition (p < 0. 05) while players performed more long passes and headed the ball more often during the six-a-side (p < 0.05). After the three-a-side games, there was a significant decline in sprint and agility performance (p < 0.05), while after both game conditions significant alterations in the throw-in and the horizontal jump performance were observed (p < 0.05). The results of the present study indicated that three-a-side games provide higher stimulus for physical conditioning and technical improvement than six-a-side games and their use for training young soccer players is recommended. Key pointsThree-a-side games display higher HR compared with six-a-side games.In the three-a-side games players performed more short passes, kicks, dribbles, tackles and scored more goals compared with the six-a-side games.Impairment in endurance and field test performance was observed mainly after three-a-side games.The use of the three-a-side games to develop physical fitness and technique in young soccer players is recommended.

Hamstring antagonist moment estimation using clinically applicable models: Muscle dependency and synergy effects.

The purpose of this study was to examine whether prediction of antagonist moment (M(flx)) of the hamstrings using clinically applicable models depends on the muscles examined. Nine healthy males performed maximal isometric knee extension and flexion contractions at 0 degrees , 45 degrees and 90 degrees angles. Calibration knee flexion efforts were also performed at different levels of intensity. The resulting electromyographic (EMG) - moment curves were fitted using polynomial equations which were then used to estimate M(flx) from the antagonist EMG. Analysis of variance designs showed that the M(flx) predicted using the biceps femoris EMG was not significantly different compared with those predicted using the semitendinosus EMG data (p>0.05). Further, prediction of M(flx) using the EMG of both muscles or a combination of EMGs and architectural properties reduced estimation error but did not provide significantly different predicted values compared with the simpler single-muscle EMG - moment models (p<0.05). It appears that M(flx) prediction using the present EMG - moment model is not muscle specific. Prediction using models which combine EMG data and anatomic parameters of the hamstring muscle components yielded more accurate estimates and therefore their use to examine co-contraction levels is recommended.

Reliability of EMG power-spectrum and amplitude of the semitendinosus and biceps femoris muscles during ramp isometric contractions.

Appropriate reliability is a necessary condition for the use of surface EMG for evaluation of hamstring muscle function in cases of knee joint pathologies or ligament injuries. The aim of the study was to investigate the test-retest reliability of power spectrum and amplitude of surface electromyographic (EMG) measurements of semitendinosus (ST) and biceps femoris (BF) during ramp isometric contractions. Eleven males performed maximum isometric contractions (MVC) of the knee flexors in two sessions, a week apart with simultaneous recording of surface EMG of the BF and ST. Intra class correlation (ICC) and standard error measurements (SEM) were applied to assess test-retest reliability of the averaged EMG (aEMG) and the median frequency (MF) over 10 levels of force, from 0% to 100% of the maximum. The ICC values ranged from 0.38 to 0.96 for the aEMG with SEM values reaching 11.37% of MVC. For the MF, the ICCs ranged from 0.44 to 0.98 (SEM range 4.49-18.19Hz). In our set up, ramp contractions can be used to examine hamstring EMG patterns with acceptable reliability.

Quantification of functional knee flexor to extensor moment ratio using isokinetics and electromyography.

CONTEXT: Evaluating moment balance around the knee helps athletic trainers set appropriate targets for injury prevention and rehabilitation programs. OBJECTIVE: To examine the knee flexor (KF) to knee extensor (KE) moment ratios using the moments when each muscle group acts as an agonist and using the moments when the KE acts as an agonist and the KF acts as an antagonist. DESIGN: Cross-sectional. SETTING: University research laboratory. PATIENTS OR OTHER PARTICIPANTS: Seventeen pubertal males (age = 13.7 +/- 0.2 years, height = 1.61 +/- 0.04 m, mass = 51.3 +/- 2.7 kg). INTERVENTION(S): The subjects performed maximal isokinetic concentric KE (KE(CON)) and eccentric KF (KF(ECC)) efforts and performed eccentric KE (KE(ECC)) and concentric KF efforts at 60 degrees /s and 180 degrees /s while we recorded the bipolar surface electromyographic (EMG) signal of the involved muscles. The KF antagonist moment was estimated from EMG-moment relationships determined during calibration KF efforts. Maximal moments were used to estimate the KF:KE ratios, and EMG-based moments were used to estimate the antagonist to agonist ratios. MAIN OUTCOME MEASURE(S): We calculated KF:KE ratios for various angular positions, velocities, and movement directions. RESULTS: The KF(ECC):KE(CON) ratio significantly increased as the knee extended (P < .05) at increased angular velocity (P < .05), reaching a value of 3.14 +/- 1.95 at full extension. The estimated knee flexor antagonist to knee extensor agonist ratio also increased near full extension (0.32 +/- 0.21). CONCLUSIONS: Although the KFs have a higher capacity to produce maximal moment near knee extension and at increased angular velocities, knee joint movement is achieved through a balanced coactivation of the 2 antagonistic muscle groups to maintain joint stability and movement efficiency. The combined use of moment and EMG data can provide additional useful information regarding muscle balance around the knee.

Biomechanical characteristics and determinants of instep soccer kick.

Good kicking technique is an important aspect of a soccer player. Therefore, understanding the biomechanics of soccer kicking is particularly important for guiding and monitoring the training process. The purpose of this review was to examine latest research findings on biomechanics of soccer kick performance and identify weaknesses of present research which deserve further attention in the future. Being a multiarticular movement, soccer kick is characterised by a proximal-to-distal motion of the lower limb segments of the kicking leg. Angular velocity is maximized first by the thigh, then by the shank and finally by the foot. This is accomplished by segmental and joint movements in multiple planes. During backswing, the thigh decelerates mainly due to a motion-dependent moment from the shank and, to a lesser extent, by activation of hip muscles. In turn, forward acceleration of the shank is accomplished through knee extensor moment as well as a motion-dependent moment from the thigh. The final speed, path and spin of the ball largely depend on the quality of foot-ball contact. Powerful kicks are achieved through a high foot velocity and coefficient of restitution. Preliminary data indicate that accurate kicks are achieved through slower kicking motion and ball speed values. Key pointsSoccer kick is achieved through segmental and joint rotations in multiple planes and via the proximal-to-distal sequence of segmental angular velocities until ball impact. The quality of ball - foot impact and the mechanical behavior of the foot are also important determinants of the final speed, path and spin of the ball.Ball speed values during the maximum instep kick range from 18 to 35 msec(-1) depending on various factors, such as skill level, age, approach angle and limb dominance.The main bulk of biomechanics research examined the biomechanics of powerful kicks, mostly under laboratory conditions. A powerful kick is characterized by the achievement of maximal ball speed. However, maximal ball speed does not guarantee a successful kick: in each case, the ball must reach the target. As already explained, when the player is instructed to hit the ball accurately, joint and segment velocities are lower as opposed to a fast and powerful kick performance. It is therefore apparent that future research should focus on biomechanics of fast but accurate kicking.

Knee biomechanics of the support leg in soccer kicks from three angles of approach.

PURPOSE: To examine knee joint kinematics, electromyographic (EMG) activity patterns and ground reaction forces (GRF) during an instep soccer kick from three different approaches relative to the ball. METHODS: Ten male soccer players performed maximum kicks from 0 rad (K0), 0.81 rad (K45), and 1.62 rad (K90) angle between the players' starting position and the position of the ball. GRF data and 3-D kinematics and EMG activity of the vastus medialis (VM), vastus lateralis (VL), and biceps femoris (BF) muscles of the lower leg were recorded. RESULTS: colon; Compared with K0, K90, and K45 demonstrated higher medial and posterior GRF and lower anterior GRF. K90 and K45 also demonstrated higher external rotation displacement, maximum flexion, internal rotation, abduction, and adduction velocity of the tibia relative to the femur of the support leg compared with K0 (P < 0.01). The BF EMG before and immediately after ground contact was also higher in K90 and K45 compared with K0 (P < 0.01). CONCLUSION: Soccer kicks using a high angle of approach increase the medial and posterior GRF, which is indicative of an altered stance during the kick, resulting in an altered balance. Such kicks are accompanied by significant alterations in knee joint kinematics and an increased BF activation around ground contact. Soccer kicks from an angled approach may induce significant loads to knee joint structures of the support leg.