Physical match demands across different playing positions during transitional play and high-pressure activities in elite soccer.

This study explored physical match demands across different playing positions during transitional play, to inform the need for position-specific training interventions. Data was collected using 10 Hz GPS units from 10 competitive matches including 23 elite soccer players of the 1st Polish Division (Ekstraklasa) in season 2020-21. A total of 4249 positional observations were made; center backs (n = 884), full backs (n = 972), central defensive midfielders (n = 236), central attacking midfielders (n = 270), central midfielders (n = 578), wingers (n = 778), and attackers (n = 531). Match data reflected distances covered per minute (m · min-1): total distance (TD), high-speed running distance (HSRD, > 19.8 km · h-1), sprint distance (SD, > 25.2 km · h-1), and the frequency of high-intensity accelerations and decelerations (A+D, > 3 m · s-2; n · min-1). Total absolute sprint distance (SD, > 25.2 km · h-1) and total relative sprint distance (Rel B5) were also quantified. A univariate analysis of variance revealed position-specific differences. Significant effects of position were found for all analysed metrics during transitional play (large ESs; p <.001). Central attacking midfielders displayed higher TD (m · min-1), fullbacks covered highest SD (m · min-1) and wingers achieved the highest A+D (n · min-1) (p ≤ 0.05). Centre backs displayed the lowest physical outputs when compared to all other positions, except in A+D (n · min-1) during defensive transitions (p ≤ 0.05). Attackers displayed the highest physical metrics during high pressure activities (p ≤ 0.05). Coaches should carefully consider positional transitional demands to better inform training design. With specific attention paid to drills that replicate game play.

Day Type and Start Time May Influence Sleep in Adolescent Professional Football Players.

This study assessed whether scheduling (start time and day type) and workload variables influenced sleep markers (activity monitor) in professional academy footballers (n=11; 17.3±0.7 yrs) over a 10-week in-season period. Separate linear mixed regressions were used to describe the effect of start time on the previous nights sleep, and the effect of day type (match day, match day+1) and workload on subsequent sleep. Workload variables were modelled by day (day), 7-day (acute), and 28-day (chronic) periods. Sleep duration following match day+1 (400 mins; 95%CI:368-432) was significantly reduced compared to all other day types (p<0.001). Sleep onset time following match day (00:35; CI:00:04-01:12) and wake time on match day+1 (09:00; CI:08:37-09:23) were also significantly later compared to all other day types (p<0.001). Sleep duration (19.1 mins; CI:9.4-28.79), wake time (18 mins; CI:9.3-26.6), and time in bed (16.8 mins; CI:2.0-31.5) were significantly increased per hour delay in start time. When no activity was scheduled, sleep duration (37 mins; CI:18.1-55.9), sleep onset (42.1 mins; CI:28.8-56.2), and wake times (86 mins; CI:72-100) were significantly extended, relative to a 09:00 start time. Day, acute, and chronic workloads were associated with sleep onset and wake times only. Scheduled start times were associated with changes in sleep duration. Therefore, delaying start times may increase sleep in this population.

A bespoke sleep monitoring and sleep hygiene intervention improves sleep in an U18 professional football player: A case study.

This case study reports on a professional football player (age: 17.6 years) who was referred for sleep monitoring and intervention after reporting excessive night-time awakenings. The player undertook a series of subjective sleep assessments and objective sleep monitoring (activity monitor). Based on the data presented, a sleep hygiene intervention was prescribed. Numerical comparisons were made between pre-intervention (Pre) and post-intervention (Post) values. Objective values were also compared to reference data from a similarly aged professional cohort from the same club (n = 11). Wake episodes per night (Pre: 7.9 ± 3, Post: 4.5 ± 1.9; -43%) and wake after sleep onset (WASO; Pre: 74.3 ± 31.8 mins, Post: 50.0 ± 22.8 mins, -33%) were improved from Pre to Post. Compared to the reference data, mean wake episodes per night (Pre: 7.9 ± 3.0, reference: 4.6 ± 2.6; -42%) and WASO (Pre: 74.3 ± 31.8 mins, reference: 44.3 ± 36.5 mins; -40%) were all lower compared to Pre levels. Whilst causality cannot be proven, we observed multiple sleep metrics improving following an intervention. This provides a potential framework for practitioners looking to provide targeted sleep assessment and intervention.

Postactivation Potentiation for Muay Thai Kicking Performance.

ABSTRACT: Brown, L, Doyle, G, Bruce-Low, S, Domingos, S, Anthony, K, Rowan, F, and Galbraith, A. Postactivation potentiation for Muay Thai kicking performance. J Strength Cond Res 37(10): 2032-2037, 2023-The purpose of this study was to investigate the effects of postactivation potentiation (PAP) on Muay Thai kicking performance based on 3 different rest intervals. Aiming to quantify and indicate timing protocols for conditioning coaches when training athletes using PAP. 17 male (25.3 ± 3.6 years old; 179.3 ± 2.3 cm; 78.0 ± 5.2 kg), experienced Muay Thai fighters completed a standardized warm-up, including a 10-minute cycle on the Wattbike at 60 watts and 30 body mass squats for a dynamic stretch. Subjects then completed a baseline test by striking a PowerKube using the roundhouse and Teep kick techniques. PAP exercise consisted of 4 squat repetitions to maximum effort, followed by a rest period of 2, 5, or 8 minutes. Subjects then struck the PowerKube again using the roundhouse and Teep kick techniques. Rest periods were presented in a randomized order on separate days, with 72 hours between conditions. The level of significance was set at α = 0.05. Significant increases in both roundhouse (χ 2 (3) = 38.51, p < 0.05) and Teep kick (χ 2 (3) = 26.33, p < 0.05) striking power were observed when compared with baseline. For the roundhouse kick, significant differences and large effect sizes were present between all conditions except baseline and 2-minute rest. For the Teep kick, significant differences and large effect sizes were present between baseline and 5-minute rest and baseline and 8-minute rest. This indicates that PAP with 5- or 8-minute rest increased roundhouse and Teep kick power. This research reports that a PAP stimulus from a 4RM squat exercise, followed by a 5- or 8-minute rest period, enhances kick power in trained Muay Thai fighters. This technique provides a readily available, time-efficient method to enhance performance that can be built into the warm-up procedure of athletes before training or competition.

Spikes in acute:chronic workload ratio (ACWR) associated with a 5-7 times greater injury rate in English Premier League football players: a comprehensive 3-year study.

OBJECTIVES: We examined the relation between global positioning system (GPS)-derived workloads and injury in English Premier League football players (n=33) over three seasons. METHODS: Workload and injury data were collected over three consecutive seasons. Cumulative (1-weekly, 2-weekly, 3-weekly and 4-weekly) loads in addition to acute:chronic workload ratios (ACWR) (acute workload (1-week workload)) divided by chronic workload (previous 4-week average acute workload) were classified into discrete ranges by z-scores. Relative risk (RR) for each range was then calculated between injured and non-injured players using specific GPS variables: total distance, low-intensity distance, high-speed running distance, sprint distance, accelerations and decelerations. RESULTS: The greatest non-contact injury risk was when the chronic exposure to decelerations was low (<1731) and the ACWR was >2.0 (RR=6.7). Non-contact injury risk was also 5-6 times higher for accelerations and low-intensity distance when the chronic workloads were categorised as low and the ACWR was >2.0 (RR=5.4-6.6), compared with ACWRs below this. When all chronic workloads were included, an ACWR >2.0 was associated with a significant but lesser injury risk for the same metrics, plus total distance (RR=3.7-3.9). CONCLUSIONS: We recommend that practitioners involved in planning training for performance and injury prevention monitor the ACWR, increase chronic exposure to load and avoid spikes that approach or exceed 2.0.

The 3-minute all-out cycling test is sensitive to changes in cadence using the Lode Excalibur Sport ergometer.

This study investigated the effect cadence has on the estimation of critical power (CP) and the finite work capacity (W') during the 3-minute all-out cycling test. Ten participants completed 8 tests: 1) an incremental test to calculate gas exchange threshold (GET), maximal aerobic power (MAP) and peak oxygen uptake (V̇O2peak), 2-4) three time-to-exhaustion tests at 80, 100 and 105% MAP to calculate CP and W', 5-7) four 3-minute all-out tests to calculate end power (EP) and work done above EP (WEP) using cadences ranging from preferred -5 to preferred +10 rev·min-1 to set the fixed resistance. Significant differences were seen between CP and EP-preferred (267.5 ± 22.6 W vs. 296.6 ± 26.1 W, P < 0.001), CP and EP-5 (267.5 ± 22.6 W vs. 303.6 ± 24.0 W, P < 0.001) and between CP and EP+5 (267.5 ± 22.6 W vs. 290.0 ± 28.0 W, P = 0.002). No significant differences were seen between CP and EP+10 (267.5 ± 22.6 W vs. 278.1 ± 30.9 W, P = 0.331). Significant differences were seen between W' and WEP at all tested fixed resistances. EP is reduced when cycling at higher than preferred cadences, providing better estimates of CP.

The Reliability and Validity of the 3-min All-out Cycling Critical Power Test.

Research suggests that critical power (CP) can be estimated from a single 3-min bout of all-out cycling. The purpose of this study was to investigate the reliability and validity of the 3-min all-out cycling test when carried out at a constant cadence (isokinetic) and against a fixed resistance (linear). 12 participants completed 8 tests: 1) a ramp test; 2-4) 3 fixed power tests to calculate CP and W' using the 1/time mathematical model; 5-8) four 3-min all-out tests to calculate EP and WEP; 2 isokinetic and 2 linear tests. There was no significant difference between EP-isokinetic and CP (P=0.377). There were significant differences between EP-linear and CP (P=0.004), WEP-isokinetic and W' (P<0.001) and WEP-linear and W' (P<0.001). The coefficient of variation in EP-isokinetic, EP-linear, WEP-isokinetic and WEP-linear was 1.93, 1.17, 8.44 and 5.39%, respectively. The 3-min all-out isokinetic test provides a reliable estimate of EP and a valid estimate of CP. The 3-min all-out linear test provides a reliable estimate of EP, but not a valid estimate of CP. Furthermore, these results suggest that the 3-min all-out test should not be used to estimate W'.

A review of the specificity of exercises designed for conditioning the lumbar extensors.

OBJECTIVE: To review the specificity of exercises designed to condition the lumbar extensor musculature (ie, lumbar erector spinae and multifidus). METHODS: A review of studies examining effects of exercises designed to condition the lumbar extensors was conducted. Included were studies that examined the acute activation and chronic adaptation of the lumbar extensor musculature in response to benches and roman chair trunk extensions, free weights exercises (ie, deadlifts, squats, good-mornings, etc), floor and stability ball exercise (ie, trunk extensions, bridging, four-point kneeling, etc) and resistance machines (ie, those with and without pelvic restraints). RESULTS: Evidence suggests that the reviewed exercises designed to condition the lumbar extensors all may result in significant activation of this musculature during their performance. However, examination of training studies shows that for benches and roman chair trunk extensions, free weights exercises, floor and stability ball exercise and resistance machines without appropriate pelvic restraints, evidence suggests that they may be less effective for inducing chronic adaptations in the lumbar extensors as a result of their performance. Contrastingly, resistance machines that employ appropriate pelvic restraint to isolate lumbar extension are better evidenced to confer specific adaptations to the lumbar extensors. CONCLUSIONS: Numerous exercise approaches have been designed with the intention of conditioning the lumbar extensors. Those examined appear to activate the lumbar extensors; however, the specificity of many of these exercises for producing chronic adaptations may be questionable, potentially due to the compound nature of them allowing involvement of other musculature such as the hip extensors. Many of the reviewed exercises offer potential to condition the lumbar extensors, however, isolation of lumbar extension through appropriate pelvic restraint appears important for optimising specific adaptations in the lumbar extensors.

Optimal recovery time for postactivation potentiation in professional soccer players.

Resistance exercise may acutely enhance muscle contractile activity, which is known as postactivation potentiation (PAP). Postactivation potentiation augments important skills that require power production that are necessary during soccer performance. The aim of this study was to determine the optimal recovery time to elicit PAP after a bout of high-intensity resistance exercise in professional soccer players. Twenty-two senior professional soccer players (mean [SD]; age, 23 [4.5] years; stature, 1.83 [6.6] m; body mass, 80.9 [7.8] kg) were randomized to either an experimental (n = 11) or a control group (n = 11). Both groups performed a standardized warm-up and baseline countermovement jump (CMJ) followed by a 10-minute recovery. The control group then performed a CMJ at 15 seconds and at 4, 8, 12, 16, and 20 minutes, whereas the experimental group performed a 3 repetition maximum (RM) squat and then an identical CMJ protocol. No significant differences were found between the groups for CMJ peak power (p > 0.05) or jump height (p > 0.05). No time effect for peak power (F(6,60) = 2.448; p = 0.063) or jump height (F(6,60) = 2.399; p = 0.089) was observed throughout the experimental group trials. Responders (n = 6) displayed individualized PAP profiles at 4 (n = 3), 12 (n = 1), and 16 (n = 2) minutes after conditioning contraction, whereas nonresponders (n = 5) did not. A set of 3RM squats failed to acutely potentiate all participants CMJ performance. Both PAP responders and nonresponders were identified and have individualized PAP time constants. This is not consistent with the previous literature, which used identical protocols. Strength and conditioning practitioners need to individualize recovery "windows" and identify athletes who respond to PAP before undertaking a complex training intervention.

The association between physical outputs and match outcome across different playing styles for a professional second-tier football team across two complete seasons.

BACKGROUND: Elite-level football requires an array of physical, technical, psychological, and tactical skills. The aim of this study was to measure the association between physical outputs (distance, decelerations, accelerations) and the match outcome (win, draw, lose) in professional football. This research also examined whether the same association is influenced if a team adopts a possession or transition-based playing style. METHODS: Thirty-six elite-outfield football players from an English Championship team participated in the study during the 2020/2021 and 2021/2022 seasons using physical and event data collected from an English Championship club over the 2020-2021 and 2021-2022 seasons, this study conducted a univariate analysis of variance (ANOVA) and Hedge g effect size (ES) to measure the research aims. RESULTS: The results showed no significant differences were found between match outcomes for each physical output metric calculated. There was a trivial ES shown for all conditions except decelerations, with win/lose having a moderate ES (g=0.53). When playing a possession-based playing style there was no significant difference or non-trivial ES found for any physical output and match outcomes. When playing a transition-based playing style there was a moderate ES found for win/draw (P=0.38, g=0.90) and win/loss (P=0.98, g=0.64). CONCLUSIONS: This research provides important evidence for utilizing intense deceleration actions as a physical KPI during match play for teams adopting a transitional playing style. Subsequently, training interventions should be adopted to physically prepare players to complete and sustain intense deceleration actions during match play.

Worst Case Scenarios in Soccer Training and Competition: Analysis of Playing Position, Congested Periods, and Substitutes.

Aim: To understand mean (WCSmean) and peak (WCSpeak) worst case scenarios within training and game play in male professional soccer. Methods: Thirty-one (n = 31) first team players were monitored across 37 matches and 14 MD-3 sessions. Playing status was distinguished, football drills analyzed, and performance explored in long-period: >6 days, moderate-period: 5-6 days, and congested-period: ≤4 days. Relative total distance (TD), high-speed running distance (HSRD, >19.8 km·h-1), sprint distance (SD, >25.2 km·h-1), accelerations/decelerations (A+D, >3 m·s-2), accelerations (Acc, >3 m·s-2), and decelerations (Dec, >-3 m·s-2) were measured as well as Maximum acceleration (Max Acc; m·s-2) and deceleration (Max Dec; m·s-2). Results: Analysis of variance found differences between matches and training in WCSmean for TD, HSRD, SD, and Max Dec in all positions (p < .001; partial η2 > .275). Fullbacks displayed differences between match and training in Max Acc (moderate ESs; p < .001), while center backs and central midfielders in Max Dec (large ESs; p > .05). Main effects of playing status were discovered for all metrics except Max Dec (p < .001; partial η2 > .124). Analysis showed differences between long- and congested-period for A+D and Dec (large ESs; p ≤ .05). Conclusions: Findings provide more insights into short peak intensity demands of soccer showing that the maximum high velocity action of acceleration and deceleration is not being replicated in training. Nonstarters lack maximum intensity exposure in matches (WCSpeak) increasing the gap between training and competition even higher during congested fixture periods.

Isometric Exercise Training and Arterial Hypertension: An Updated Review.

Hypertension is recognised as a leading attributable risk factor for cardiovascular disease and premature mortality. Global initiatives towards the prevention and treatment of arterial hypertension are centred around non-pharmacological lifestyle modification. Exercise recommendations differ between professional and scientific organisations, but are generally unanimous on the primary role of traditional aerobic and dynamic resistance exercise. In recent years, isometric exercise training (IET) has emerged as an effective novel exercise intervention with consistent evidence of reductions in blood pressure (BP) superior to that reported from traditional guideline-recommended exercise modes. Despite a wealth of emerging new data and endorsement by select governing bodies, IET remains underutilised and is not widely prescribed in clinical practice. This expert-informed review critically examines the role of IET as a potential adjuvant tool in the future clinical management of BP. We explore the efficacy, prescription protocols, evidence quality and certainty, acute cardiovascular stimulus, and physiological mechanisms underpinning its anti-hypertensive effects. We end the review with take-home suggestions regarding the direction of future IET research.

The development of a custom-built portable impact-testing device for assessing the cushioning properties of athletic socks.

Despite manufacturer claims that athletic socks attenuate force during exercise, no device exists to assess this. Therefore, this study outlines the development of a custom-built impact-testing device for assessing the cushioning properties of socks. The device used a gravity-driven impact striker (8.5 kg), released from 0.05 m, which impacted a no-sock, sock or a basic shoe/sock condition in the vertical axis. A load cell (10,000 Hz) assessed peak impact force, time to peak impact force and loading rate. Reliability was investigated between day, between trial and within trial. Excellent reliability (coefficient of variation < 5% adjusted for 95% confidence limits) was reported for peak impact force in all conditions, with no evidence of systematic bias. Good reliability (coefficient of variation < 10% adjusted for 68% confidence limits) was reported for time to peak impact force and loading rate with some evidence of systematic bias. It was concluded that the custom-built impact-testing device was reliable and sensitive for the measurement of peak impact force on socks.

The Development of a Custom Built Portable Impact Testing Device for Assessing the Cushioning Properties of Athletic Socks.

Despite manufacturer claims that athletic socks attenuate force during exercise, no device exists to assess this. Therefore, this study outlines the development of a custom built impact testing device for assessing the cushioning properties of socks. The device utilised a gravity driven impact striker (8.5 kg), released from 0.05 m, which impacted a no sock, sock or a basic shoe/sock condition in the vertical axis. A load cell (10000 Hz) assessed peak impact force, time to peak impact force and loading rate. Reliability was investigated between day, between trial and within trial. Excellent reliability (coefficient of variation < 5% adjusted for 95% confidence limits) was reported for peak impact force in all conditions, with no evidence of systematic bias. Good reliability (coefficient of variation < 10% adjusted for 68% confidence limits) was reported for time to peak impact force and loading rate with some evidence of systematic bias. It was concluded that the custom built impact testing device was reliable and sensitive for the measurement of peak impact force on socks.

One lumbar extension training session per week is sufficient for strength gains and reductions in pain in patients with chronic low back pain ergonomics.

Chronic low back pain (CLBP) is the leading cause of absenteeism from the workplace and research into exercise interventions to address this problem is required. This study investigated training frequency for participants with CLBP. Participants either trained once a week (1 × week, n = 31), or twice a week (2 × week, n = 20) or did not (control group, n = 21). Participants were isometric strength tested in weeks 1 and 12 and trained dynamically either 1×week (80% of maximum) or 2×week (80% and 50%). The results (pre vs. post) showed significant increases in maximal strength, range of motion and reductions in pain for both training groups. Pain scores for the 1 × week and 2 × week both reached minimal clinical improvement change unlike the control group. Thus, one lumbar extension training session per week is sufficient for strength gains and reductions in pain in low back pain in CLBP patients. PRACTITIONER SUMMARY: CLBP is the leading cause of absenteeism from the workplace. The present study using a modified randomised control trial design investigated exercise training frequency for participants with CLBP. One lumbar extension training session per week is sufficient for strength gains and reductions in low back pain in CLBP patients.

WITHDRAWN: The Development of a Custom Built Portable Impact Testing Device for Assessing the Cushioning Properties of Athletic Socks.

Ahead of Print article withdrawn by publisher.

Isolated Lumbar Extension Resistance Training Improves Strength, Pain, and Disability, but Not Spinal Height or Shrinkage ("Creep") in Participants with Chronic Low Back Pain.

Objective. Loss of disc height is commonly associated with chronic low back pain (CLBP). Isolated lumbar extension (ILEX) exercise for the lumbar extensors is recommended to treat CLBP and is suggested such exercise might promote disc healing and regeneration. This study examined a 12-week ILEX intervention on indirect determination of disc height and shrinkage through seated stadiometry, strength, pain, and disability. Design. A quasi-experimental wait-list controlled design was used. Nine participants underwent pretesting (T1), a 12-week control period, retesting (T2), a 12-week intervention period, and finally posttesting (T3). Seated stadiometry, ILEX strength, pain, and disability were measured at each time point. Results. No significant repeated-measures effects for any seated stadiometry variables occurred. Significant improvement across the intervention period (T2 to T3) was found for strength (P <0.0001; effect size [ES] = 2.42). Change in pain was not significant for repeated effects (P = 0.064); however, ES for the intervention period (T2 to T3) was moderate (ES = -0.77). Change in disability was significant between time point T1 and T3 (P = 0.037) and ES for the intervention period (T2 to T3) was large (ES = -0.92). Pain and disability achieved minimal clinically important changes. Conclusions. This is apparently the first study to examine disc change in vivo after exercise in CLBP. Results of the present study, though supporting ILEX resistance training to improve strength, pain, and disability, did not find any effect on spinal height.

Does change in isolated lumbar extensor muscle function correlate with good clinical outcome? A secondary analysis of data on change in isolated lumbar extension strength, pain, and disability in chronic low back pain.

PURPOSE: Secondary analysis of data from studies utilising isolated lumbar extension exercise interventions for correlations among changes in isolated lumbar extension strength, pain, and disability. MATERIALS AND METHODS: Studies reporting isolated lumbar extension strength changes were examined for inclusion criteria including: (1) participants with chronic low back pain, (2) intervention ≥ four weeks including isolated lumbar extension exercise, (3) outcome measures including isolated lumbar extension strength, pain (Visual Analogue Scale), and disability (Oswestry Disability Index). Six studies encompassing 281 participants were included. Correlations among change in isolated lumbar extension strength, pain, and disability. Participants were grouped as "met" or "not met" based on minimal clinically important changes and between groups comparisons conducted. RESULTS: Isolated lumbar extension strength and Visual Analogue Scale pooled analysis showed significant weak to moderate correlations (r = -0.391 to -0.539, all p < 0.001). Isolated lumbar extension strength and Oswestry Disability Index pooled analysis showed significant weak correlations (r = -0.349 to -0.470, all p < 0.001). For pain and disability, isolated lumbar extension strength changes were greater for those "met" compared with those "not met" (p < 0.001-0.008). CONCLUSIONS: Improvements in isolated lumbar extension strength may be related to positive and meaningful clinical outcomes. As many other performance outcomes and clinical outcomes are not related, isolated lumbar extension strength change may be a mechanism of action affecting symptom improvement. Implications for Rehabilitation Chronic low back pain is often associated with deconditioning of the lumbar extensor musculature. Isolated lumbar extension exercise has been shown to condition this musculature and also reduce pain and disability. This study shows significant correlations between increases in isolated lumbar extension strength and reductions in pain and disability. Strengthening of the lumbar extensor musculature could be considered an important target for exercise interventions.