Male Semi-professional Soccer Players Research Articles

Biceps femoris muscle-tendon strain during an entire overground sprint acceleration: a biomechanical explanation for hamstring injuries in the acceleration phase

ABSTRACT The objectives of this study were to analyse the peak muscle-tendon (MT) strain of the hamstring during an entire acceleration sprint overground and examine their relationship with relative joint angles and segment orientation in the sagittal plane, which are the direct causes of MT strain. Kinematic data were recorded using a 3D inertial motion capture system in 21 male semi-professional soccer players during 40-metre overground sprint. Scaled musculoskeletal models were used to estimate peak MT strain in the hamstring over 16 steps. Biceps femoris long head (BFLH) exhibited the largest peaks in MT strain compared to semitendinosus (ST) and semimembranosus (SM) muscles across all the steps, with its overall strain decreased as the number of steps and maximum speed increased. Hip flexion angle was found to be a strong predictor (p < 0.001) of joint angles, being the orientation of the pelvis in the sagittal plane of the segment with the greatest influence (p < 0.001) on the peak MT strain of BFLH during sprinting. The current study provides a biomechanical explanation for the high proportion of hamstring injuries in the acceleration phase of sprinting.

Small-sided-games with coaches' verbal encouragement have a positive effect on aerobic performance, mood state, satisfaction and subjective effort in male semi-professional soccer players

The study aimed to examine the impact of high-intensity Small-Sided Games (SSGs) with coaches’ verbal encouragement (VE) on soccer players’ aerobic performance, mood state, satisfaction and subjective effort. Forty-three semi-professional male soccer players were randomly assigned to three distinct groups: a control group (CG, n = 14), an experimental group with verbal encouragement (EGVE, n = 14), and an experimental group without verbal encouragement (EGNE, n = 15). Participants performed the VAMEVAL aerobic test, Total-Mood-Disorder (TMD), and the Satisfaction Scale for Athletes (SSA) tests before and following the 6-week SGGs program that included ten training sessions. Rating of Perceived Exertion (RPE) was collected 5-minutes post-training session. The SGGs program with coaches’ VE showed a significant improvement in maximal aerobic velocity (MAV) and TMD scores (p &lt; 0.05). Except for the SSA scores (p = 0.268), the percentage of change was higher for MAV (p = 0.001; d: 1.36–1.48 (large)) and TMD scores (p = 0.001; d: 1.45–1.48 (large)) in the EGVE group when compared with the other groups (i.e., EGNE and CG). Overall, RPE scores were significantly higher (p ˂ 0.05; d: 0.99–5.00 (large)) in the EGVE group than other groups. The present study highlights the positive effects of integrating SSGs with coaches VE to improve aerobic performance and mental well-being of semi-professional soccer players. Nevertheless, notably the SSA did not exhibit a statistically significant difference. Furthermore, the experimental EGVE group reported elevated RPE, potentially suggesting that SSGs may entail greater physical and mental challenges, yet may yield more sport-specific outcomes for soccer players.

Is a Maximal Strength-Training Program Effective on Physical Fitness, Injury Incidence, and Injury Burden in Semi-Professional Soccer Players? A Randomized Controlled Trial.

The aims of the study were to analyze the effects of a 12-week maximal strength- training program on injury incidence, injury burden, and physical fitness in semi-professional soccer players and to compare the perceived exertion load and well-being state between injured and non-injured soccer players. Twenty semi-professional male soccer players participated in this study. Participants were randomly allocated to an experimental group (EG, n = 10 players), who performed a maximal strength-training program, or to a control group (CG, n = 10 players), who only performed their regular soccer training. Physical fitness was measured at baseline and after the training program. In addition, the injury incidence, burden, training/match load, and the state of well-being of the players were recorded. The EG showed significant improvements in vertical jumps, change in direction ability, linear sprints, repeated sprint ability, isometric strength (p < 0.003; effect size = 1.78-11.86), and quadriceps-hamstring imbalance in both legs (p < 0.001; effect size = 2.37-3.71) in comparison to the CG. In addition, the EG players showed a significantly (p < 0.05) lower injury burden (p < 0.001, relative risk = 5.05, 95% confidence interval = 3.27-7.79). This study demonstrated the beneficial effects of a 12-week maximal strength-training program on physical fitness attributes and injury burden in semi-professional soccer players.

Effects of 16-weeks of strength training on jump height and anthropometric variables in U19 semi-professional male soccer players

Purpose The aim of our study was to examine the effect of 16 weeks of strength training on anthropometric characteristics and jump height in semi-professional male players after a pre-season period. Methods A parallel two-group, longitudinal (pre, post) design was used with physical tests performed before (preintervention) and after (postintervention) the 16-week intervention period. The soccer players were assigned and matched into two groups, an experimental group (EG) and a control group (CG), based on the team of which they were a part. Results A two-way ANOVA was performed with group and time as factors. The results of a two-way ANOVA revealed no time×group interaction for body composition or jump height. Nevertheless, a paired measures t-test of weight, fat mass, lean mass, and countermovement jump (CMJ) test metrics (pre-post) and group (CG and EG) showed an improvement in all measures ( p &lt; 0.01). Discussion The 16-week intervention program resulted in an improvement in the EG both at the level of body composition and in CMJ performance. Conclusions Despite the benefits of the 16-week intervention program, a combination of training methods that includes power, agility-coordination, speed, and strength can enhance such improvements. It is important to take this strength-specific capacity into account in training, due to the importance outlined in the sport of soccer both for its transfer to both linear and COD sprints and specific strength skills and mainly to vertical jump.

Effects of Different Recovery Duration on External and Internal Load Measures during Bouts of Small-Sided Games.

The aim of this study was to analyse the effects of different recovery times between bouts of small-sided games (SSG) on external and internal load variables in semi-professional soccer players. Sixteen male semi-professional soccer players performed three 4 vs. 4 + goalkeeper SSG training sessions, each with different recovery bout duration: short (1 min) (SSG1), medium (2 min) (SSG2), and long (4 min) (SSG4). Time motion and neuromuscular measures were collected during all SSGs, in addition, the rating of perceived exertion (RPE) was determined at the end of the last bout of each SSG. Results showed a significant increase in the total number of accelerations (p = 0.016, ES = 0.97, large) and decelerations (p = 0.022, ES = 0.81, large) in SSG4 compared to SSG1. In terms of the internal load, SSG2 showed significantly higher RPE values (p = 0.011, ES = 1.00, large) in comparison with SSG1. If the sessions' focus is on neuromuscular training, longer recovery times between SSG bouts should be used. Conversely, if the aim is to reach a higher total and running distance at different intensities, a 2-min recovery period between bouts may be more appropriate.

Is there association between cutting and jump-landing movement quality in semi-professional football players? Implications for ACL injury risk screening

ObjectivesTo investigate the relationship between the Landing Error Scoring System (LESS) and Cutting Movement Assessment Score (CMAS) to evaluate movement quality, their intra- (INTRAob) and inter-observer (INTERob) reliability, and the comparison between the two drop vertical jump (DVJ) landings (1st and 2nd). DesignCross-sectional. Participants42 male semi-professional soccer players performed three trials of DVJ and 70° change of direction with a ball located as an external focus. Main outcome measuresMovement quality was evaluated through 2D video footage using the CMAS and LESS, screened by two observers. Relational, comparative and reliability analyses were conducted. ResultsBoth tools showed moderate to substantial (ICC = 0.58–0.71), and substantial to almost perfect (ICC = 0.68–0.87) INTRAob and INTERob reliability, respectively. No significant associations were found among CMAS, LESS 1st and 2nd for either scores or risk profiles (r = −0.158–0.202, p > 0.05). LESS 2nd was moderately higher (ES = 0.80–0.83, p = 0.002–0.007) than 1st scores. ConclusionsCMAS and LESS are reliable tools to evaluate movement quality, although evaluations should be preferably performed by the same observer; ACL injury risk profile's is task-dependent; both landings of the DVJ should be assessed as they represent different biomechanical and neuromuscular control deficits.

The effects of jump training on measures of physical performance, lower extremities injury incidence and burden in highly trained male soccer players

ABSTRACT This study aimed to analyse the effects of a 16-week jump training program on the physical performance and lower extremities injury profile in semi-professional male soccer players. Participants were randomly assigned to the control group (CG; n = 13; age = 21.7 ± 3.6 years) or the experimental group (EG; n = 10; age = 22.3 ± 3.5 years). Countermovement jump (CMJ) height (cm), 30 m linear sprint time (s) with split times at 10 m and 20 m distances, and change of direction speed (CODS; 10 + 10 m with 90° turn) time (s) with turns using the dominant or non-dominant leg, were assessed before and after the intervention. Lower extremity injuries sustained throughout the intervention period were collected. Significant within-group improvements were found in EG in CMJ (p = 0.01; effect size [ES] = 1.03; large). Additionally, between-group difference after intervention was found in CMJ (F = 4.42; p = 0.013) in favour of EG. Injury burden was 194.86 (CG) vs 71.37 (EG) days of absence/1,000 h (RR = 2.73; 95% CI 2.10–3.54; p < 0.001). No other significant within-group or between-group differences were found. In conclusion, compared to regular soccer training, jump training was effective to improve jumping ability and burden in soccer players.

Acute effects of beetroot juice and caffeine co-ingestion during a team-sport-specific intermittent exercise test in semi-professional soccer players: a randomized, double-blind, placebo-controlled study

BackgroundBeetroot juice (BJ) and caffeine (CAF) are considered as ergogenic aids among athletes to enhance performance, however, the ergogenic effects of BJ and CAF co-ingestion are unclear during team-sport-specific performance. This study aimed to investigate the acute effects of BJ and CAF co-ingestion on team-sport-specific performance, compared with placebo (PL), BJ, and CAF alone.MethodSixteen semi-professional male soccer players (age: 19.8 ± 2.2 years, body mass: 69.2 ± 6.1 kg, height: 177.3 ± 6.0 cm) completed four experimental trials using a randomized, double-blind study design: BJ + CAF, CAF + PL, BJ + PL, and PL + PL. Countermovement jump with arm swing (CMJAS) performance and cognitive function by Stroop Word-Color test were evaluated before and after the Yo–Yo Intermittent Recovery Test level 1 (YYIR1). Also, rate of perceived exertion (RPE), heart rate, and gastrointestinal (GI) discomfort were measured during each session.ResultsNo significant differences were shown between test conditions for total distance covered in YYIR1 (BJ + CAF: 1858 ± 455 m, CAF + PL: 1798 ± 422 m, BJ + PL: 1845 ± 408 m, PL + PL 1740 ± 362 m; p = 0.55). Moreover, CMJAS performance, cognitive function, and RPE during the YYIR1 were not significantly different among conditions (p > 0.05). However, the average heart rate during the YYIR1 was higher in CAF + PL compared to PL + PL (by 6 ± 9 beats/min; p < 0.05), and GI distress was greater in BJ + CAF compared to PL + PL (by 2.4 ± 3.6 a.u.; p < 0.05).ConclusionThese results suggest, neither acute co-ingestion of BJ + CAF nor BJ or CAF supplementation alone significantly affected team-sport-specific performance compared to the PL treatment.

Effects of Whole-Season Training and Match-Play on Hip Adductor and Abductor Muscle Strength in Soccer Players: A Pilot Study.

Previous investigations have associated weakness of hip muscles with a higher likelihood of developing hip groin injury. However, no previous investigation has examined the influence of soccer training and match-play during the season on maximal isometric hip adductor and abductor muscle strength. Maximal hip adductor and abductor muscle strength would increase after the preseason, maintaining relatively constant levels across the soccer season. Cross-sectional study. Level 3. A total of 26 semiprofessional male soccer players underwent measurements of maximal isometric hip adductor and abductor muscle strength at 3 time points of the soccer season: preseason, midseason, and end-season to investigate the longitudinal effect of soccer training and competition during a complete season on maximal isometric hip adductor and abductor muscle strength in the semiprofessional Spanish soccer player. Compared with preseason, hip abductor muscle strength increased in the midseason (14.2% and 17.1%, for dominant and nondominant limb, respectively; P < 0.001) and in the end-season (13.1%; P = 0.005, and 14.1%; P < 0.005). In contrast, hip adductor muscle strength remained unchanged across the season in both limbs. As a result, the adductor/abductor strength ratio in the nondominant limb was reduced at midseason and end-season time points (-14.6% and -18.4%, respectively; P < 0.001) with a corresponding tendency in the dominant limb (-9.3% and -15.0%, respectively; P > 0.05). While maximal hip abductor muscle strength increased throughout the season, hip adductor muscle strength remained stable across the season. This produced a substantial deficit in hip adductor/abductor strength ratio at midseason and end-season. The progressive imbalance in adductor/abductor strength across the soccer season may be an indicator of increased risk of groin injury and may reinforce the need for preventive rehabilitation activities focused on enhancing adductor muscle strength.

Assessing Inter-Limb Asymmetries in Soccer Players: Magnitude, Direction and Association with Performance.

In this study, we aimed to analyze the magnitude and direction of inter-limb asymmetries in ankle dorsiflexion range of motion (ROM), power (using iso-inertial devices), and a neuromuscular skill (change of direction). Secondarily, we aimed to determine the relationship between inter-limb asymmetry scores for each test and also between these scores and the scores for the different performance tests. Sixteen semiprofessional male soccer players (age: 25.38 ± 6.08 years; body height: 1.78 ± 0.64 m; body mass: 79.5 ± 14.9 kg) participated in this study. We calculated inter-limb asymmetries using five tests: ankle dorsiflexion ROM, change of direction (COD 180º), and iso-inertial resistance tasks in the open (leg extension strength (LE), leg curl strength (LC)) and closed (crossover step (CRO)) kinetic chain. Our results showed that asymmetry magnitudes differed between all tests with highest inter-limb asymmetries displayed during iso-inertial overloading. In addition, we observed that the direction of asymmetries varied depending on the test-specificity, and that the CRO asymmetries had a negative association with LE and CRO performance. These findings highlight the independent nature of asymmetries and that CRO could be an appropriate test to detect asymmetries related with the performance of soccer-specific actions (such as changes of direction). Practitioners are encouraged to use multiple tests to detect existing inter-limb differences according to the specific characteristics of each sport.

Effects of Different Recovery Times on Internal and External Load During Small-Sided Games in Soccer.

The ability to maintain a high intensity of exercise over several repetitions depends on recovery from previous exercises. This study aimed to identify the effects of different recovery times on internal and external load during small-sided soccer games. An increase in recovery time will increase the external training load and decrease the internal exercise load, which will result in a greater physical impact of the exercise. Cross-sectional study. Level 2. Twenty male semiprofessional soccer players participated in the present study. They performed the same exercise (5-a-side game format) continuously (1 × 18 minutes) and repeatedly/fractionated (3 × 6 minutes) with different recovery times (30 seconds, 1 minute, 1.5 minutes, and 2 minutes). Their internal load (ie, average heart rate (HR) and maximum HR) and external load (ie, total distance, maximum speed, and ratio meters) were measured using an HR band and an inertial device equipped with a global positioning system, respectively. The manipulation of recovery times induced differences in the internal and external load. For the same total duration, the external and internal load indicators exhibited higher values during the fractionated method, particularly with short recovery periods. The application of small-sided soccer games with different recovery times induced varying responses in training load. To maintain high physical performance and high training load, the fractional method with short recovery periods (ie, 30 seconds) should be used. In contrast, to carefully manage players' efforts and decrease response to training load, continuous or fractional methods with longer recovery periods (ie, 1-2 minutes) should be used. The proper prescription of recovery time between exercises facilitates enhanced training efficiency and optimized performance.

Head impacts in semiprofessional male Soccer players: a prospective video analysis over one season of competitive games

ABSTRACT Soccer exposes players to head injuries and involves repeated intentional head impacts through heading the ball. Our objective was to investigate the rate of both intentional headers and involuntary head impacts in semiprofessional male soccer players during one season. In this prospective cohort study, we followed 54 men (16–35 years) playing in two soccer clubs participating in the same regional French championship throughout the 2017–2018 season. All head impacts that occurred in competitive games were analyzed using video recordings. Player position, game exposure, referee’s decision were also reported. Head impact incidence rate (IR) per 1000 player-hours, with the 95% confidence intervals (CIs) were calculated. Results: Headers IR was 3584.7 per 1000 player-hours (95% CI = 3431.9, 3737.5). Forwards and center-backs performed a higher number of headers. Involuntary head impacts IR was 44.1/1000 player-hours (95% CI = 27.1, 60.9). Just under half led the referee to stop playing time for a caregiver examination. Three concussions with a loss of consciousness after a head-to-head impact in a heading duel were recorded. Conclusions: Intentional headers were relatively common, contrary to involuntary head impacts that were however mainly due to heading duels. Head-to-head impact should lead to a systematic exit from the game for suspicion of concussion.

An Investigation into the Relationship Between Heart Rate Recovery in Small-Sided Games and Endurance Performance in Male, Semi-professional Soccer Players

BackgroundThe ability to recover in the shortest possible time plays an important role especially in intermittent sports such as soccer. Evidence suggests that a well-developed endurance performance has positive effects on the repeated-sprint ability and thus also on the short-term recovery. However, it has not been clarified whether these relationships still exist in a soccer-specific situation. Therefore, the purpose of this investigation was to evaluate the ability of semi-professional soccer players to recover during standardized small-sided games (SSGs) as an endurance performance indicator.MethodsEighteen male semi-professional soccer players (age, 23.5 ± 3.7 years) performed an incremental treadmill test (ITT) to determine their running velocity and heart rate at a fixed lactate threshold of 4 mmol L−1 (v4). Two days later, the players carried out six bouts of 4 vs. 4 SSGs (duration, 90 s; load to rest ratio, 1:1). A GPS-based tracking system was used to determine distances covered at four fixed speed zones (i.e., < 7.2 km/h, 7.2–14.4 km/h, 14.4–19.8 km/h, > 19.8 km/h) and total distance covered during the SSGs. Furthermore, the frequency of occurrence of accelerations (> 1.54 m s−2) was calculated. SSGs’ internal load was quantified by average heart rate and blood lactate concentration after the SSGs. Their recovery ability was evaluated using heart rate recovery (HRR) after the last bout of the SSGs.ResultsA very large correlation (r = − .91) with an explained variance of 84% was found between HRR and v4. Further, a better performance in the ITT was also related with a higher number of accelerations executed during SSGs (r = .60). The total distance and distances in predefined speed zones did not show any association to v4.ConclusionsThis study showed a strong relationship between HRR after standardized 4 vs. 4 SSGs and the soccer players’ endurance performance in a laboratory setting. Thus, besides being associated with endurance capacity, v4 seems sufficient to evaluate the sport-specific ability to recover in soccer players.

Sodium Bicarbonate Supplementation Does Not Improve Running Anaerobic Sprint Test Performance in Semiprofessional Adolescent Soccer Players.

Ergogenic strategies have been studied to alleviate muscle fatigue and improve sports performance. Sodium bicarbonate (NaHCO3) has improved repeated sprint performance in adult team-sports players, but the effect for adolescents is unknown. The aim of the present study was to evaluate the effect of NaHCO3 supplementation on repeated sprint performance in semiprofessional adolescent soccer players. In a double-blind, placebo-controlled, crossover trial, 15 male semiprofessional adolescent soccer players (15 ± 1years; body fat 10.7 ± 1.3%) ingested NaHCO3 or a placebo (sodium chloride) 90min before performing the running anaerobic sprint test (RAST). A countermovement jump was performed before and after the RAST, and ratings of perceived exertion, blood parameters (potential hydrogen and bicarbonate concentration), and fatigue index were also evaluated. Supplementation with NaHCO3 promoted alkalosis, as demonstrated by the increase from the baseline to preexercise, compared with the placebo (potential hydrogen: +0.07 ± 0.01 vs. -0.00 ± 0.01, p < .001 and bicarbonate: +3.44 ± 0.38 vs. -1.45 ± 0.31mmol/L, p < .001); however, this change did not translate into an improvement in RAST total time (32.12 ± 0.30 vs. 33.31 ± 0.41s, p = .553); fatigue index (5.44 ± 0.64 vs. 6.28 ± 0.64W/s, p = .263); ratings of perceived exertion (7.60 ± 0.33 vs. 7.80 ± 0.10 units, p = .525); countermovement jump pre-RAST (32.21 ± 3.35 vs. 32.05 ± 3.51cm, p = .383); or countermovement jump post-RAST (31.70 ± 0.78 vs. 32.74 ± 1.11cm, p = .696). Acute NaHCO3 supplementation did not reduce muscle fatigue or improve RAST performance in semiprofessional adolescent soccer players. More work assessing supplementation in this age group is required to increase understanding in the area.

Effects of score-line on internal and external load in soccer small-sided games

ABSTRACT The aim of this study was to analyse the effect of the score-line on the internal and external load in soccer small-sided games (SSGs). Thirty male semi-professional soccer players participated in an acute crossover design study. Players performed 4 series of 4 vs 4 with a game duration of 4 min. The data corresponding to players’ external load were collected using a portable Global Positioning System device and players’ internal load using rating of perceived exertion. The results showed that players covered significantly higher total distance (effect size [ES]: 0.63–55), medium-intensity distance (ES: 0.81–82), and high-intensity running distance (ES: 0.86–0.53) when the final result of SSGs was a draw in comparison when losing or winning. Players’ power score was significantly higher when the final result of SSGs was a draw compared to when was a loss (ES: 0.77). On the contrary, players covered significantly shorter walking distance when drawing compared to losing (ES: 0.55) and winning (ES: 0.63). Present results indicate players’ external load during SSGs is related to the final score-line. In order to maximise players’ external load during SSGs, teams should be as balance as possible to increase the probability of a draw score-line.

Train Like You Compete? Physical and Physiological Responses on Semi-Professional Soccer Players.

Background: Decision-making in soccer has repercussions and depends on the environment of training or competition. The demands on the players can reveal if the decision-making is similar or different from that required during competition. Objectives: The aim of this study was to assess the physical and physiological responses of players in training matches (TM) and official competition matches (CM) according to the playing position (external defenders, internal defenders, midfielders, and forwards/extremes). Methods: Twenty semi-professional male soccer players and 10 CM (n = 40) and 10 TM (n = 40) were studied using global positioning system technology, and paired and one-way ANOVA tests were carried out to compare physical (distances and number of sprints) and physiological (heart rates) responses with the factors a) match environments (TM and CM) and b) the playing position, respectively. Results: The results revealed that during CM, players covered higher total distance, partial distances, and sprints at different speeds (0–21 km/h) and produced higher physiological responses. Midfielders covered the greatest total distance in both TM (7227.6 m) and CM (11,225.9 m), in comparison to the other playing positions. However, forwards and extremes spent more time (56.8% of the CM [d = 0.78]) at 76% to 84% of their maximal heart rates. Conclusions: First, the physical and physiological responses in TM were significantly lower than in CM. Second, these responses were different according to the playing position, so this study was able to verify the exact amount of variation between the load produced in TM and CM. These results will help the coach and technical staff to design training tasks to complement the responses found in TM.

Improvements in strength and functional performance after Kinesio taping in semi-professional male soccer players with and without functional ankle instability

ObjectiveThe objectives of this study were to compare the immediate effects of two methods of Kinesio taping on muscle strength, functional performance, and balance in athletes with and without functional ankle instability (FAI). MethodsThe present study investigated the effects of distal taping (muscle application over peroneus longus) and proximal- distal taping (muscle application over gluteus medius and peroneus longus) on the strength of evertor and hip abductor muscles, side hop test, figure of 8 hop test, and star excursion balance test in semi-professional male soccer players with and without FAI (n=15 in each group). A Multifactorial repeated measure ANOVA was used for comparison. ResultsThere were significant differences for factor effect in all outcome measures (P<0.05), except for the figure of 8 hop test. No significant differences for group effects and group by factor interaction effects (P>0.05) was observed except for the side hop test. ConclusionKinesio taping had immediate effects on improving strength, performance and balance. However, there were no differences on the method of application. Clinicians can consider the application Kinesio taping during the rehabilitation process of athletes with FAI, to improve balance and strength. The long-term impacts of taping on the functional, balance and strength measures should be investigated in future studies.

The Effect of Phase Change Material on Recovery of Neuromuscular Function Following Competitive Soccer Match-Play.

Aim: Cryotherapy is commonly implemented following soccer match-play in an attempt to accelerate the natural time-course of recovery, but the effect of this intervention on neuromuscular function is unknown. The aim of the present study was to examine the effect of donning lower-body garments fitted with cooled phase change material (PCM) on recovery of neuromuscular function following competitive soccer match-play.Methods: Using a randomized, crossover design, 11 male semi-professional soccer players wore PCM cooled to 15°C (PCMcold) or left at ambient temperature (PCMamb; sham control) for 3 h following soccer match-play. Pre-, and 24, 48, and 72 h post-match, participants completed a battery of neuromuscular, physical, and perceptual tests. Maximal voluntary contraction force (MVC) and twitch responses to electrical (femoral nerve) and magnetic (motor cortex) stimulation (TMS) during isometric knee-extension and at rest were measured to assess central nervous system (CNS) (voluntary activation, VA) and muscle contractile (quadriceps potentiated twitch force, Qtw,pot) function. Fatigue and perceptions of muscle soreness were assessed via visual analog scales, and physical function was assessed through measures of jump [countermovement jump (CMJ) height and reactive strength index (RSI)] performance. A belief questionnaire was completed pre- and post-intervention to determine the perceived effectiveness of each garment.Results: Competitive soccer match-play elicited persistent decrements in MVC, VA measured with femoral nerve stimulation, Qtw,pot, as well as reactive strength, fatigue and muscle soreness (P < 0.05). Both MVC and VA were higher at 48 h post-match after wearing PCMcold compared with PCMamb (P < 0.05). However, there was no effect of PCM on the magnitude or time-course of recovery for any other neuromuscular, physical function, or perceptual indices studied (P > 0.05). The belief questionnaire revealed that players perceived that both PCMcold and PCMamb were moderately effective in improving recovery, with no difference between the two interventions (P = 0.56).Conclusion: Although wearing cooled PCM garments improved MVC and VA 48 h following match-play, the lack of effect on measures of physical function or perceptual responses to match-play suggest that PCM offers a limited benefit to the recovery process. The lack of effect could have been due to the relatively small magnitude of change in most of the outcome measures studied.

Physical Response to a Simulated Period of Soccer-Specific Fixture Congestion.

Page, RM, Marrin, K, Brogden, CM, and Greig, M. Physical response to a simulated period of soccer-specific fixture congestion. J Strength Cond Res 33(4): 1075-1085, 2019-The aim of this study was to assess the physiological, perceptual, and mechanical measures associated with the completion of a simulated period of short-term soccer-specific fixture congestion. Ten male semiprofessional soccer players completed 3 trials of a treadmill-based match simulation, with 48 hours interspersing each trial. A repeated measures general linear model identified significantly (p = 0.02) lower knee flexor peak torque (PT) recorded at 300°·s in the second (141.27 ± 28.51 N·m) and third trials (139.12 ± 26.23 N·m) when compared with the first trial (154.17 ± 35.25 N·m). Similarly, muscle soreness (MS) and PT data recorded at 60°·s were significantly (p ≤ 0.05) different in the third trial (MS = 42 ± 25 a.u; PT60 = 131.10 ± 35.38 N·m) when compared with the first trial (MS = 29 ± 29 a.u; PT60 = 145.61 ± 42.86 N·m). Significant (p = 0.003) differences were also observed for mean electromyography (EMGmean) of bicep femoris between the third trial (T0-15 = 126.36 ± 15.57 μV; T75-90 = 52.18 ± 17.19 μV) and corresponding time points in the first trial (T0-15 = 98.20 ± 23.49 μV; T75-90 = 99.97 ± 39.81 μV). Cumulative increases in perceived exertion, heart rate, oxygen consumption, blood lactate concentrations, EMGmean, and PlayerLoad (PL) were recorded across each trial. Muscle soreness and PT were also significantly different after trial. There were, however, no significant main effects or interactions for the salivary immunoglobulin A and the medial-lateral PL metrics. These data suggest a biomechanical and muscular emphasis with residual fatigue, with implications for injury risk and the development of recovery strategies.

Effects of Small-Sided Game Variation on Changes in Hamstring Strength.

Madison, G, Patterson, SD, Read, P, Howe, L, and Waldron, M. Effects of small-sided game variation on changes in hamstring strength. J Strength Cond Res 33(3): 839-845, 2019-Small-sided games (SSGs) are commonly used by soccer practitioners to condition players. This form of exercise can result in fatigue, potentially exposing the muscle to injury risk. The purpose of this study was to determine the effects of SSG variations on hamstring torque in semiprofessional soccer players. In a counterbalanced cross-over design, 10 male semiprofessional soccer players took part in both small relative area (3 vs. 3; 300 m) and large relative area (4 vs. 4; 1000 m) SSGs. The games comprised 6 × 4-minute bouts, with 90-second recovery. Both movement and heart rate responses were monitored by global positioning systems (GPS) and hamstring isometric torque was measured pre-training and post-training using a NordBord. There were differences (p < 0.05) between the small and large relative area games for peak hamstring force decrement (5.78 N and -13.62 N, respectively) and mean hamstring force decrement at 90° (11.11 N and -4.78 N, respectively). The number of accelerations was related to (r = 0.46, p = 0.039) reduced hamstring peak torque at 90°. In conclusion, larger relative area SSGs elicited the greatest internal and external loads, resulting in decrements in hamstring force. The number of accelerations performed in the session increases the likelihood of hamstring fatigue and can be controlled with the relative pitch area.