Variability of internal and external loads and technical/tactical outcomes during small-sided soccer games: a systematic review

Small-sided games (SSGs) are widely used in soccer training. However, some of the typical outcomes related to human responses during these games (namely internal and external load) may vary between sessions for similar practice conditions. Thus, the study of intra- and inter-bout variability in response to SSGs is progressively growing. This systematic review aimed to (1) identify studies that have examined the intra- and inter-session bouts’ variability levels regarding the internal and external load and technical/tactical outcomes during SSGs and (2) summarize the main evidence. A systematic review of PubMed, SPORTDiscus, Cochrane, and Web of Science databases was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. From the 486 studies initially identified, 24 were fully reviewed, and their outcome measures were extracted and analyzed. Sixteen studies analyzed internal load, 13 studies analyzed external load variables, six studies analyzed technical execution, and two studies analyzed tactical behavior. All studies included SSGs with a range number of players between 2 to 14 (1 vs. 1 to 7 vs. 7 SSGs). Internal load and low-speed external load variables presented a low variability, while high variations were reported regarding the technical execution and high-speed external loads.     

Effects of plyometric jump training on soccer player’s balance: a systematic review and meta-analysis of randomized-controlled trials

Plyometric jump training (PJT) can be used for improving balance through bilateral and unilateral jump-landing drills. Since the increased number of articles testing the effects of PJT on dynamic and static balance, it is relevant to summarize the evidence and determine the effects across different original articles. This systematic review with meta-analysis was conducted to assess the effects of PJT programs on dynamic and static balance in soccer players. The data sources utilized were Cochrane, Medline (PubMed), SPORTDiscus, and Web of Science. (i) Soccer players of any age or sex without injury, illness, or other clinical conditions; (ii) PJT-based programs restricted to a minimum of three weeks (duration); (iii) passive or active control groups; (iv) pre-post interventions values of dynamic and/or static balance; (v) randomized-controlled trials; and (vi) peerreviewed original full-text studies written in English, Portuguese, and/or Spanish. The database search initially identified 803 titles. From those, eight articles were eligible for the systematic review and meta-analysis. The results showed no significant differences between PJT and active controls in dynamic anterior, postero-medial, or postero-lateral balance for both left and right legs (p > 0.05). Additionally, no significant differences were found between PJT and active controls in terms of static balance (p = 0.495). The current evidence suggests that PJT has no significant advantage over active control groups in terms of dynamic or static balance.     

Worst case scenario match analysis and contextual variables in professional soccer players: a longitudinal study

This study aimed to describe the worst-case scenarios (WCS) of professional soccer players by playing position in different durations and analyse WCS considering different contextual variables (match half, match location and match outcome). A longitudinal study was conducted in a professional soccer team. Data were collected from different WCS durations in the total distance (TD), high-speed running distance (HSRD), and sprinting distance (SPD). A mixed analysis of variance was performed to compare different WCS durations between playing positions and contextual variables, making pairwise comparisons by Bonferroni post hoc test. Positional differences were found for TD (p < 0.01, ω_p² = 0.02), HSRD (p < 0.01, ω_p² = 0.01) and SPD (p < 0.01, ω_p² = 0.02). There was a significant interaction when comparing WCS by match half in TD (F = 6.1, p < 0.01, ω_p² = 0.07) but no significant differences in HSRD (p = 0.403, ω_p² = 0) or SPD (p = 0.376, ω_p² = 0). A significant interaction was identified when comparing WCS by match location in TD (F = 51.5, p < 0.01, ω_p² = 0.14), HSRD (F = 19.15, p < 0.01, ω_p² = 0.05) and SPD (F = 8.95, p < 0.01, ω_p² = 0.01) as well as WCS by match outcome in TD (F = 36.4, p < 0.01, ω_p² = 0.08), HSRD (F = 13.6, p < 0.01, ω_p² = 0.04) and SPD (F = 7.4, p < 0.01, ω_p² = 0.02). Positional differences exist in TD, HSRD, and SPD in match-play WCS, and contextual variables such as match half, match location and match outcome have a significant impact on the WCS of professional soccer players.     

Effects of an individualized soccer match simulation on vertical stiffness and impedance

An observed relationship between soccer match duration and injury has led to research examining the changes in lower extremity mechanics and performance with fatiguing exercise. Because many fatigue protocols are designed to result in substantial muscular deficits, they may not reflect the fatigue associated with sport-specific demands that have been associated with the increasing incidence of injury as the match progresses. Thus, the aim of this study was to systematically analyze the progressive changes in lower extremity mechanics and performance during an individualized exercise protocol designed to simulate a 90-minute soccer match. Previous match analysis data were used to systematically develop a simulated soccer match exercise protocol that was individualized to the participant's fitness level. Twenty-four National Collegiate Athletic Association Division I soccer players (12 men, 12 women) participated in 2 testing sessions. In the first session, the participants completed the Yo-Yo Intermittent Recovery Test Level 1 to assess their fitness level and determine the 5 submaximal running intensities for their soccer match simulation. In the second test session, progressive changes in the rating of perceived exertion (RPE), lower extremity performance (vertical jump height, sprint speed, and cutting speed), and movement mechanics (jumping vertical stiffness and terminal landing impedance) were measured during the soccer match simulation. The average match simulation running distance was 10,165 ± 1,001 m, consistent with soccer match analysis research. Time-related increases in RPE, and decrements in sprinting, and cutting speed were observed, suggesting that fatigue increased as the simulation progressed. However, there were no time-related decreases in vertical jump height, changes in lower extremity vertical stiffness in jumping, or vertical impedance during landing. Secondary analyses indicated that the coordinative changes responsible for the maintenance of stiffness and impedance differed between the dominant and nondominant limbs. Despite an increase in RPE to near exhaustive levels, and decrements in sprint and cutting performance, the participants were able to maintain jump performance and movement mechanics. Interestingly, the coordinative changes that allowed for the maintenance of vertical stiffness and impedance varied between limbs. Thus, suggesting that unilateral training for performance and injury prevention in soccer-specific populations should be considered.     

Predicted sweat rates for group water planning in sport: accuracy and application

This study tested the accuracy of a novel, limited-availability web application (H₂Q™) for predicting sweat rates in a variety of sports using estimates of energy expenditure and air temperature only. The application of predictions for group water planning was investigated for soccer match play. Fourteen open literature studies were identified where group sweat rates were reported (n = 20 group means comprising 230 individual observations from 179 athletes) with fidelity. Sports represented included: walking, cycling, swimming, and soccer match play. The accuracy of H₂Q™ sweat rates was tested by comparing to measured group sweat rates using the concordance correlation coefficient (CCC) with 95% confidence interval [CI]. The relative absolute error (RAE) with 95% [CI] was also assessed, whereby the mean absolute error was expressed relative to an acceptance limit of 0.250 L/h. The CCC was 0.98 [0.95, 0.99] and the RAE was 0.449 [0.279, 0.620], indicating that the prediction error was on average 0.112 L/h. The RAE was < 1.0 for 19/20 observations (95%). Drink volumes modeled as a proxy for sweat losses during soccer match play prevented dehydration (< 1% loss of body mass). The H₂Q™ web application demonstrated high group sweat prediction accuracy for the variety of sports activities tested. Water planning for soccer match play suggests the feasibility of easily and accurately predicting sweat rates to plan group water needs and promote optimal hydration in training and/or competition.     

Differences in worst-case scenarios calculated by fixed length and rolling average methods in professional soccer match-play

The aims of this study were to describe the worst-case scenarios (WCS) in professional soccer players calculated by fixed length and rolling average methods with regards to each playing position. This was done, firstly, by comparing total distance (TD covered in the WCS; secondly, by comparing high-speed running distance (HSRD); and thirdly, by comparing sprint distance (SPD). The study was conducted over a three-mesocycle competitive period. The WCS of three distance-related variables (TD, HSRD, SPD) in four time windows (1, 3, 5, 10 minutes) were calculated according to playing position (central defender; full-back; midfielder, wide midfielder, and forward) using fixed length and rolling average methods. A significant effect of the type of method used to calculate the WCS in TD (F_{(1, 142)} = 151.49, p < 0.001, ηp² = 0.52), HSRD (F_{(1, 138)} = 336.95, p < 0.001, ηp² = 0.71) and SPD (F_{(1, 138)} = 76.74, p < 0.001, ηp² = 0.36) was observed. In addition, there was a significant interaction between type of method and WCS duration in TD (F_{(1.36, 193.53)} = 41.95, p < 0.001, ηp² = 0.23), HSRD (F_{(2.28, 315.11)} = 21.77, p < 0.001, ηp² = 0.14) and SPD (F_{(2.59, 358.41)} = 6.93, p < 0.001, ηp² = 0.05). In conclusion, the use of fixed length methods of different durations significantly underestimated the WCS of TD, HSRD and SPD across the most common playing positions in professional soccer players. Therefore, the application of rolling averages is recommended for an appropriate WCS analysis in professional soccer match-play.     

Combining small-sided soccer games and running-based methods: A systematic review

Small-sided games (SSGs) are often used in soccer to produce acute physiological and physical responses, while a tactical/technical stimulus is also employed. However, due to some limitations of SSGs, researchers have been testing this method combined with running-based training methods. This systematic review was conducted to assess the effects of combined SSG and running-based methods on soccer players’ acute responses and adaptations after training interventions. A systematic review of Web of Science, PubMed, Cochrane Library, Scopus, and SPORTDiscus databases was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The database search initially identified 782 titles. From those, five articles were deemed eligible for the systematic review. The five included studies presented data from training load, reporting inconsistent greater values in combined SSG and running-based methods when compared to SSG-only formats. Considering the adaptations, studies comparing combined SSG and running-based methods with SSG-only methods revealed inconsistent differences in terms of the effects on aerobic performance and sprinting. Combining SSG and running-based methods can increase the acute mechanical load and high-intense running stimuli in players when compared to interventions that use only SSGs. However, the adaptations promoted by both methods are similar, and the differences are unclear. The order of combination (SSG and running-based method) does not seem to impact players’ adaptations; however, the frequency of sessions did have a meaningful impact.     

The dominant leg is more likely to get injured in soccer players: systematic review and meta-analysis

In soccer (football), dominant limb kicking produces higher ball velocity and is used with greater frequency than the non-dominant limb. It is unclear whether limb dominance has an effect on injury incidence. The purpose of this systematic review with meta-analysis is to examine the relationship between limb dominance and soccer injuries. Studies were identified from four online databases according to PRISMA guidelines to identify studies of soccer players that reported lower extremity injuries by limb dominance. Relevant studies were assessed for inclusion and retained. Data from retained studies underwent meta-analyses to determine relative risk of dominant versus non-dominant limb injuries using random-effects models. Seventy-four studies were included, with 36 of them eligible for meta-analysis. For prospective lower extremity injury studies, soccer players demonstrated a 1.6 times greater risk of injury to the dominant limb (95% CI [1.3–1.8]). Grouped by injury location, hamstring (RR 1.3 [95% CI 1.1–1.4]) and hip/groin (RR 1.9 [95% CI 1.3–2.7]) injuries were more likely to occur to the dominant limb. Greater risk of injury was present in the dominant limb across playing levels (amateurs RR 2.6 [95% CI 2.1–3.2]; youths RR 1.5 [95% CI 1.26–1.67]; professionals RR 1.3 [95% CI 1.14–1.46]). Both males (RR 1.5 [95% CI 1.33–1.68)] and females (RR 1.5 [95% CI 1.14–1.89]) were more likely to sustain injuries to the dominant limb. Future studies investigating soccer injury should adjust for this confounding factor by using consistent methods for assigning limb dominance and tracking use of the dominant versus non-dominant limb.     

Effect of competition on salivary cortisol, immunoglobulin A, and upper respiratory tract infections in elite young soccer players

The present study examined the effect of a 20-day period of competition on salivary cortisol, mucosal immunity, and upper respiratory tract infections (URTI) in young male soccer players (n = 14). The players were monitored during the main under-19 Brazilian soccer championship, in which 7 matches were played in 20 days. Saliva samples were collected in the morning of each match and analyzed for cortisol and immunoglobulin A (IgA). Signs and symptoms of URTI were assessed across the study and a rating of perceived exertion (RPE) was obtained for each match. Compared with match 1, a significant increase in player RPE was observed in matches 4-7 (p < 0.05). Significant (p < 0.05) increases in the reporting of URTI occurred between matches 2 and 3, and 6 and 7, and this was accompanied by significant decreases in salivary IgA levels. Significant (p < 0.05) correlations were also seen between the individual reports of URTI and the decrease in IgA levels in match 2 (r = -0.60) and match 6 (r = -0.65). These results suggest that decrements in mucosal immunity, as measured by salivary IgA concentrations, may lead to a greater incidence of URTI in elite young soccer players. It may be speculated that the physiological and psychological stressors imposed by training and competition in a short timeframe are major contributing factors to these responses. Thus, the monitoring of salivary IgA could provide a useful and noninvasive approach for predicting URTI occurrences in young athletes during short-term competitions, especially if frequent sampling and rapid measurements are made.     

Heart rate and blood lactate concentrations as predictors of physiological load on elite soccer players during various soccer training activities

The purpose of this investigation was to estimate the physiologic strain on players during various soccer training activities. Ten soccer players from the first division soccer league of Turkey were used as subjects. The heart rate responses were measured during 4 types of soccer training. First, the heart rates that corresponded to a blood lactate concentration of both 2 and 4 mM were measured, and then, during the 4 types of training, they were correlated with the proportion of time that the heart rate was below the 2-mM lactate line, between the 2- and 4-mM lactate lines, and above the 4-mM lactate line. Mean heart rates during friendly match, modified game, tactical training, and technical training activities were 157 +/- 19, 135 +/- 28, 126 +/- 21, and 118 +/- 21 b.min(-1), respectively. The differences between all of these soccer training activities were statistically significant (p < or = 0.01). The results demonstrate that (a) technical and tactical training consisted of very low exercise intensities (most of the heart rates were below the 4-mM lactate level) and (b) the percentages of time that the heart rate correlated to a point above the 4-mM lactate reference level during the friendly match and modified game were 49.6 +/- 27.1% and 23.9 +/- 24.5%, respectively. The practical implications of these findings are that, by using 2- to 4-mM reference lines, coaches can structure heart rate zones that can help determine the individualized exercise intensity for their players as well as estimate overall exercise intensity during soccer training.     

Heart Rate Monitoring in Soccer: Interest and Limits During Competitive Match Play and Training, Practical Application

ABSTRACT: Alexandre, D, Da Silva, C, Hill-Haas, S, Wong, DP, Natali, AJ, De Lima, JRP, Filho, MGB, Marins, JCB, Garcia, ES, and Chamari, K. Heart rate monitoring in soccer: Interest and limits during competitive match play and training-Practical application. J Strength Cond Res 26(10): 2890-2906, 2012-The identification of physiological loads imposed by soccer training or match play reveals essential information, which may help improve training and recovery strategies. Until today, the use of heart rate (HR) monitoring is not standardized in soccer. Thus, the aim of this review was to analyze, determine and compare the exercise intensity (EI) monitored by HR in professional, youth, and recreational soccer players during matches and training sessions using a meta-analysis. Heart rate is one of the most common physiological variables used to determine exercise internal training load. The mean EI recorded during competitive matches was described as 70-80% of V[Combining Dot Above]O2max or 80-90% of maximal heart rate (HRmax), independent of the playing level. With respect to HR training zones, approximately 65% of the total match duration is spent at intensity of 70-90% HRmax and rarely below 65% HRmax. However, although HRmax is mostly employed in the literature, monitoring EI should be expressed in relation to reserve heart rate, as it was described as a more reliable indicator of HR, allowing interindividual comparisons. The HR response according to the playing position indicates that midfielders are characterized by the highest EI, followed by forwards and fullbacks. Moreover, in the second half of the match, the EI is lower than that observed during the first half; this reduction could be correlated with the level of the player's physical conditioning. Consequently, coaches may favor the use of interval training or small-sided training games because these are shown to improve both aerobic capacity and the ability to repeat high-intensity actions. Small-sided games allow reaching similar HR responses to those found during interval training and match play but with greater heterogeneity values. Future investigations should include a larger sample of players with special reference to playing position and the expression of EI in percentage of the reserve heart rate, analyzing the possible intergender differences in HR response.     

Parasympathetic Nervous System Dysfunction,as Identified by Pupil Light Reflex,and Its Possible Connection to Hearing Impairment

ContextAlthough the pupil light reflex has been widely used as a clinical diagnostic tool for autonomic nervous system dysfunction, there is no systematic review available to summarize the evidence that the pupil light reflex is a sensitive method to detect parasympathetic dysfunction. Meanwhile, the relationship between parasympathetic functioning and hearing impairment is relatively unknown.ObjectivesTo 1) review the evidence for the pupil light reflex being a sensitive method to evaluate parasympathetic dysfunction, 2) review the evidence relating hearing impairment and parasympathetic activity and 3) seek evidence of possible connections between hearing impairment and the pupil light reflex.MethodsLiterature searches were performed in five electronic databases. All selected articles were categorized into three sections: pupil light reflex and parasympathetic dysfunction, hearing impairment and parasympathetic activity, pupil light reflex and hearing impairment.ResultsThirty-eight articles were included in this review. Among them, 36 articles addressed the pupil light reflex and parasympathetic dysfunction. We summarized the information in these data according to different types of parasympathetic-related diseases. Most of the studies showed a difference on at least one pupil light reflex parameter between patients and healthy controls. Two articles discussed the relationship between hearing impairment and parasympathetic activity. Both studies reported a reduced parasympathetic activity in the hearing impaired groups. The searches identified no results for pupil light reflex and hearing impairment.

Discussion and Conclusions

As the first systematic review of the evidence, our findings suggest that the pupil light reflex is a sensitive tool to assess the presence of parasympathetic dysfunction. Maximum constriction velocity and relative constriction amplitude appear to be the most sensitive parameters. There are only two studies investigating the relationship between parasympathetic activity and hearing impairment, hence further research is needed. The pupil light reflex could be a candidate measurement tool to achieve this goal.     

Intermatch variation of match activity in elite Italian soccer referees

The aim of this study was to examine how match activities, specifically high-intensity activity (HIA; activities performed at speeds faster than 18.1 km x h(-1)), vary among matches in elite soccer referees, because variations in match performance can potentially guide physical conditioning regimens for these referees. Fourteen Italian soccer referees were observed during 65 first-division matches a minimum of 3 and a maximum of 6 times each. For comparison, shorter matches (SM) and longer matches (LM) for each referee were identified. Mean (+/-SD) SM and LM total distances were 10,949 +/- 1,095 m and 12,303 +/- 666 m (p < 0.001), respectively. SM and LM were not different in term of duration (p > 0.05). During LM, referees spent 44% less time standing still (p < 0.01) and covered 10% more distance at low intensity than they did in SM (p < 0.05). No HIA variation was observed between SM and LM (p > 0.05). For the elite referee, work rate is increased without affecting HIA.     

Coalitional Physical Competition

A large body of research links testosterone and cortisol to male-male competition. Yet, little work has explored acute steroid hormone responses to coalitional, physical competition during middle childhood. Here, we investigate testosterone, dehydroepiandrosterone (DHEA), androstenedione, and cortisol release among ethnically Chinese boys in Hong Kong (N = 102), aged 8–11 years, during a soccer match (n = 84) and an intrasquad soccer scrimmage (n = 81), with 63 participants competing in both treatments. The soccer match and intrasquad soccer scrimmage represented out-group and in-group treatments, respectively. Results revealed that testosterone showed no measurable change. DHEA increased during both treatments in the majority of participants and the degree of change had no relation to independent variables (e.g., performance, age, treatment, outcome) or covariate measures (Body Mass Index, Pubertal Development Scale). Most boys experienced androstenedione increases during match play, but no significant differences during the intrasquad soccer scrimmage competitions. The magnitude of change differed significantly between treatments and was positively associated with age. These latter findings suggest boys’ androstenedione responses may be sensitive to competitor type (i.e., unknown competitors vs. peers). For most subjects, cortisol significantly increased during match play, decreased during the intrasquad soccer scrimmage, and differed significantly between treatments, suggesting each treatment promoted a different psychological state among competitors. Cortisol/DHEA molar ratio decreased during the intrasquad scrimmage, suggestive of a more relaxed mental state. These data shed new light on potential proximate mechanisms associated with coalitional competition among prepubescent boys, with relevance to adrenarche and life history theory.     

The Effect of Gender-Affirming Hormone Therapy on the Risk of Subclinical Atherosclerosis in the Transgender Population: A Systematic Review

ObjectiveThe impact of gender-affirming hormone therapy (GAHT) on cardiovascular (CV) health is still not entirely established. A systematic review was conducted to summarize the evidence on the risk of subclinical atherosclerosis in transgender people receiving GAHT.MethodsA systematic review was performed following Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines, and data were searched in PubMed, LILACS, EMBASE, and Scopus databases for cohort, case-control, and cross-sectional studies or randomized clinical trials, including transgender people receiving GAHT. Transgender men and women before and during/after GAHT for at least 2 months, compared with cisgender men and women or hormonally untreated transgender persons. Studies reporting changes in variables related to endothelial function, arterial stiffness, autonomic function, and blood markers of inflammation/coagulation associated with CV risk were included.ResultsFrom 159 potentially eligible studies initially identified, 12 were included in the systematic review (8 cross-sectional and 4 cohort studies). Studies of trans men receiving GAHT reported increased carotid thickness, brachial-ankle pulse wave velocity, and decreased vasodilation. Studies of trans women receiving GAHT reported decreased interleukin 6, plasminogen activator inhibitor-1, and tissue plasminogen activator levels and brachial-ankle pulse wave velocity, with variations in flow-mediated dilation and arterial stiffness depending on the type of treatment and route of administration.ConclusionsThe results suggest that GAHT is associated with an increased risk of subclinical atherosclerosis in transgender men but may have either neutral or beneficial effects in transgender women. The evidence produced is not entirely conclusive, suggesting that additional studies are warranted in the context of primary prevention of CV disease in the transgender population receiving GAHT.Systematic Review RegistrationPROSPERO, identifier CRD42022323757.     

Muscle damage, endocrine, and immune marker response to a soccer match

ABSTRACT: Thorpe, R and Sunderland, C. Muscle damage, endocrine, and immune marker response to a soccer match. J Strength Cond Res 26(10): 2783-2790, 2012-This study represents the first time that muscle damage, endocrine, and immune markers have been measured, together with activity profile, during a competitive soccer match. Seven semiprofessional soccer players participated in a competitive league match. Blood and saliva samples were obtained 1 hour before kick off and immediately postmatch. Global positioning system equipment was used to measure heart rate and activity profile data throughout the match. Percentage increase in creatine kinase (CK) and myoglobin (MYO) concentrations was correlated with the number of sprints performed during the match (r = 0.88, p = 0.019; r = 0.75, p = 0.047, respectively). Creatine kinase increased by 84% (p = 0.17) from prematch to postmatch, whereas MYO increased by 238% (p = 0.05). Players performed 39 ± 18 sprints during the course of the match. Cortisol increased by 78% (p = 0.103), whereas testosterone increased significantly by 44% (p = 0.004). No differences were seen from prematch to postmatch in the testosterone to cortisol ratio, immunoglobulin (Ig) A, IgM, or IgG. Sprinting is correlated with changes in CK and MYO and may therefore be associated with muscle damage in semiprofessional soccer players.     

Glucocorticoid-Induced Hyperglycemia Including Dexamethasone-Associated Hyperglycemia in COVID-19 Infection: A Systematic Review

ObjectiveOptimal glucocorticoid-induced hyperglycemia (GCIH) management is unclear. The COVID-19 pandemic has made this issue more prominent because dexamethasone became the standard of care in patients needing respiratory support. This systematic review aimed to describe the management of GCIH and summarize available management strategies for dexamethasone-associated hyperglycemia in patients with COVID-19.MethodsA systematic review was conducted using the PubMed/MEDLINE, Cochrane Library, Embase, and Web of Science databases with results from 2011 through January 2022. Keywords included synonyms for “steroid-induced diabetes” or “steroid-induced hyperglycemia.” Randomized controlled trials (RCTs) were included for review of GCIH management. All studies focusing on dexamethasone-associated hyperglycemia in COVID-19 were included regardless of study quality.ResultsInitial search for non-COVID GCIH identified 1230 references. After screening and review, 33 articles were included in the non-COVID section of this systematic review. Initial search for COVID-19–related management of dexamethasone-associated hyperglycemia in COVID-19 identified 63 references, whereas 7 of these were included in the COVID-19 section. RCTs of management strategies were scarce, did not use standard definitions for hyperglycemia, evaluated a variety of treatment strategies with varying primary end points, and were generally not found to be effective except for Neutral Protamine Hagedorn insulin added to basal-bolus regimens.ConclusionFew RCTs are available evaluating GCIH management. Further studies are needed to support the formulation of clinical guidelines for GCIH especially given the widespread use of dexamethasone during the COVID-19 pandemic.     

Individual match playing time during the season affects fitness-related parameters of male professional soccer players

The purpose of this study was to analyze the effects of an entire season on physical fitness parameters (PFPs) in male professional soccer players (N = 18). Performance in 5- and 30-m sprint (T5 and T30), countermovement jump (CMJ), agility (T-test), knee extensor (KE) and knee flexor (KF) isokinetic strength, hamstrings/quadriceps strength ratio (H/Q) and bilateral differences (BDs), and Yo-Yo intermittent endurance test 2 (YYIE2) was evaluated in 4 moments (E1-E4) throughout the season. Individual match playing time was quantified. Significant improvements in CMJ and YYIE2 from E1 to E2 were observed (p < 0.05-0.01). The T30 improved from E2 to E3 (p < 0.01). The CMJ decreased from E2 to E3 and E4, and YYIE2 from E2 to E4 (p < 0.05). There were increments in the H/Q ratio and Agility from E1 and E2 to E3 and E4 (p < 0.05-0.01). Significant correlations were found in all evaluation points between different PFPs and between changes in strength parameters and agility, T5 and T30, CMJ, and YYIE2 (p < 0.05-0.001). Influence of individual match playing time was correlated to changes in T5 (E1 to E3; r = -0.705), KE nondominant leg (KEND; E2 to E3; r = 0.786), and KF (E3 to E4; r = 0.575-0.590). The interrelationship between muscle strength (e.g., KE), sprint (e.g., T5), and jump abilities (CMJ) suggests the importance of muscle strength and power training for soccer. This study suggests that the systematic participation of the players in soccer matches favors the increase and maintenance of soccer players KE and KF muscle strength and sprint ability (T5). Thus, given the unique demands of actual match play, coaches should try to incorporate a competitive friendly match in the weekly training cycle of nonstarter players.     

The prevalence and practices of caffeine use as an ergogenic aid in English professional soccer

The ergogenic properties of caffeine are well established, with evidence supporting beneficial effects for physical and technical elements of performance required for successful soccer match play. Despite this, recommended caffeine practices for professional soccer have not been established. Therefore, the present study aimed to evaluate the use and behaviours surrounding caffeine use in elite English soccer clubs. Representatives of 36 clubs from the top four tiers of English professional football (40%) completed an online survey that sought to determine if, when, how and why caffeine was prescribed to players as a means of improving sports performance. Of the clubs sampled, 97% indicated that caffeine is provided to players as a means of improving performance. Caffeine is most commonly administered prior to (> 94%) and during a game (> 48%), with frequency uninfluenced by time of matches. There was a broad range and lack of consistency in the timing, dose and mode of caffeine administration, but doses were typically low. Evidence from the present study indicate a translational gap between science and practice, highlighting a need for future work to better understand how caffeine consumption can be optimised with respect to the specific demands and constraints in professional soccer.