Injury-inciting circumstances of sudden-onset hamstring injuries: video analyses of 63 match injuries in male professional football players in the Qatar Stars League (2013-2020).

OBJECTIVE: To describe and categorise the injury-inciting circumstances of sudden-onset hamstring match injuries in professional football players using systematic video analysis. METHODS: Using a prospective injury surveillance database, all sudden-onset hamstring match injuries in male football players (18 years and older) from the Qatar Stars League between September 2013 and August 2020 were reviewed and cross-referenced with broadcasted match footage. Videos with a clear observable painful event (ie, a player grabbing their posterior thigh) were included. Nine investigators independently analysed all videos to describe and categorise injury-inciting circumstances. We used three main categories: playing situation (eg, time of injury), player action(s) (eg, running) and other considerations (eg, contact). Player action(s) and other considerations were not mutually exclusive. RESULTS: We included 63 sudden-onset hamstring match injuries out of 295 registered injuries between 2013 and 2020. Running was involved in 86% of injuries. Hamstring injuries occurred primarily during acceleration of 0-10 m (24% of all injuries) and in general at different running distances (0-50 m) and speeds (slow to fast). At 0-10 m distance, indirect player-to-player contact and inadequate balance were involved in 53% and 67% of the cases, respectively. Pressing occurred in 46% of all injuries (injured player pressing opponent: 25%; being pressed by opponent: 21%) and frequently involved player-to-player contact (69% of the cases when the injured player was pressing vs 15% of the cases when the opponent was pressing) and inadequate balance (82% vs 50%, respectively). Other player actions that did not involve running (n=9, 14% of all injuries) were kicking (n=6) and jumping (n=3). CONCLUSION: The injury-inciting circumstances of sudden-onset hamstring match injuries in football varied. The most common single-player action (24%) was acceleration over a distance of <10 m. Pressing, inadequate balance and indirect contact were frequently seen player actions. Injury prevention research in football should look beyond high-speed running as the leading risk factor for sudden-onset hamstring injuries.

Are there interindividual differences in the reactive hypoglycaemia response to breakfast? A replicate crossover trial.

BACKGROUND: Following consumption of a meal, circulating glucose concentrations can rise and then fall briefly below the basal/fasting concentrations. This phenomenon is known as reactive hypoglycaemia but to date no researcher has explored potential inter-individual differences in response to meal consumption. OBJECTIVE: We conducted a secondary analysis of existing data to examine inter-individual variability of reactive hypoglycaemia in response to breakfast consumption. METHODS: Using a replicate crossover design, 12 healthy, physically active men (age: 18-30 y, body mass index: 22.1 to 28.0 kg⋅m- 2) completed two identical control (continued overnight fasting) and two breakfast (444 kcal; 60% carbohydrate, 17% protein, 23% fat) conditions in randomised sequences. Blood glucose and lactate concentrations, serum insulin and non-esterified fatty acid concentrations, whole-body energy expenditure, carbohydrate and fat oxidation rates, and appetite ratings were determined before and 2 h after the interventions. Inter-individual differences were explored using Pearson's product-moment correlations between the first and second replicates of the fasting-adjusted breakfast response. Within-participant covariate-adjusted linear mixed models and a random-effects meta-analytical approach were used to quantify participant-by-condition interactions. RESULTS: Breakfast consumption lowered 2-h blood glucose by 0.44 mmol/L (95%CI: 0.76 to 0.12 mmol/L) and serum NEFA concentrations, whilst increasing blood lactate and serum insulin concentrations (all p < 0.01). Large, positive correlations were observed between the first and second replicates of the fasting-adjusted insulin, lactate, hunger, and satisfaction responses to breakfast consumption (all r > 0.5, 90%CI ranged from 0.03 to 0.91). The participant-by-condition interaction response variability (SD) for serum insulin concentration was 11 pmol/L (95%CI: 5 to 16 pmol/L), which was consistent with the τ-statistic from the random-effects meta-analysis (11.7 pmol/L, 95%CI 7.0 to 22.2 pmol/L) whereas effects were unclear for other outcome variables (e.g., τ-statistic value for glucose: 0 mmol/L, 95%CI 0.0 to 0.5 mmol/L). CONCLUSIONS: Despite observing reactive hypoglycaemia at the group level, we were unable to detect any meaningful inter-individual variability of the reactive hypoglycaemia response to breakfast. There was, however, evidence that 2-h insulin responses to breakfast display meaningful inter-individual variability, which may be explained by relative carbohydrate dose ingested and variation in insulin sensitivity of participants.

Data analytics in the football industry: a survey investigating operational frameworks and practices in professional clubs and national federations from around the world.

The use of data and analytics in professional football organisations has grown steadily over the last decade. Nevertheless, how and whether these advances in sports analytics address the needs of professional football remain unexplored. Practitioners from national federations qualified for the FIFA World Cup Qatar 2022™ and professional football clubs from an international community of practitioners took part in a survey exploring the characteristics of their data analytics infrastructure, their role, and their value for elaborating player monitoring and positional data. Respondents from 29 national federations and 32 professional clubs completed the survey, with response rates of 90.6% and 77.1%, respectively. Summary information highlighted the underemployment of staff with expertise in applied data analytics across organisations. Perceptions regarding analytical capabilities and data governance framework were heterogenous, particularly in the case of national federations. Only a third of national federation respondents (~30%) perceived information on positional data from international sports data analytics providers to be sufficiently clear. The general resourcing limitations, the overall lack of expertise in data analytics methods, and the absence of operational taxonomies for reference performance metrics pose constraints to meaningful knowledge translations from raw data in professional football organisations.

Immediate effects of Ramadan on objective time asleep in male youth football players from the Middle East: an interrupted time-series study.

OBJECTIVE: To examine the abrupt effects of Ramadan onset on actigraphy-based time asleep in male youth Muslim football players. METHODS: We adopted a quasi-experimental, interrupted time-series research design and tracked objective time asleep over a minimum of 12 consecutive nights in the two weeks prior to and immediately after Ramadan onset, respectively. Twenty-two, male academy student-athletes (chronological age range: 12.6 to 16.2 years) participated in the study (464 individual observations). Segmented generalized mixed-effects modelling estimated the effects of Ramadan onset on time asleep during the first period of night sleep only. RESULTS: Ramadan onset led to an immediate mean reduction of 89 min (95% confidence interval [CI], 54 to 123 min) in time asleep during the first period of night sleep compared to pre-Ramadan sleep patterns. Model-adjusted estimated marginal means for time asleep were ~ 5.7 h (95%CI, 5.1 to 6.2 h) before and ~ 4.2 h (95%CI, 3.6 to 4.7 h) after Ramadan onset. Night sleep interruptions resulting in two or more fragmented periods accounted for 8% (95%CI, 2 to 21%) to 19% (95%, 11 to 29%) of sleep observations before and after Ramadan onset, respectively. CONCLUSIONS: The onset of Ramadan determined an abrupt reduction in time asleep of ~ 1 h 30 min in the first period of a night cycle and contributed to additional problems of heterogeneous sleep fragmentation that can impact optimal school learning and youth athlete performance development processes.

Night-to-night variability of objective sleep outcomes in youth Middle Eastern football players.

OBJECTIVE: To describe components of night-to-night variation in objective measures of sleep. METHODS: We conducted a secondary data analysis of consecutive and chronologically ordered actigraphy-based measurements for time in bed (min), time asleep (min), and wake-after-sleep onset (min). This investigation examined 575 individual night-based measures available for a sub-sample of fifty-two, male youth Middle Eastern football players tracked over a 14-day surveillance period (chronological age range: 12.1 to 16 years). Distinct multivariable-adjusted generalized additive models included each objective sleep outcome measure as dependent variable and disaggregated components of variation for night measurement-by-sleep period interaction, week part (weekday or weekend), and study participant random effects from within-subject night-to-night sleep variation. RESULTS: The within-subject standard deviation (SD) of ±98 min (95% confidence interval [CI], 92 to 104 min) for time in bed, ±87 min (95%CI, 82 to 93 min) for time asleep, and ±23 min (95%CI, 22 to 25 min) for wake-after-sleep-onset overwhelmed other sources of variability and accounted for ∼44% to 53% of the overall night-to-night variation. The night measurement-by-fragmented sleep period interaction SD was ±83 min (95%CI, 44 to 156 min) for time in bed, ±67 min (95%CI, 34 to 131 min) for time asleep, and ±15 min (95%CI, 7 to 32 min) for wake-after-sleep-onset that accounted for ∼22% to 32% of each sleep outcome measure overall variability. CONCLUSIONS: Substantial random night-to-night within-subject variability poses additional challenges for strategies aiming to mitigate problems of insufficient and inconsistent sleep that are detrimental to school learning and youth athlete development processes.

Are There Interindividual Responses of Cardiovascular Disease Risk Markers to Acute Exercise? A Replicate Crossover Trial.

PURPOSE: Using a replicated crossover design, we quantified the response heterogeneity of postprandial cardiovascular disease risk marker responses to acute exercise. METHODS: Twenty men (mean (SD) age, 26 (6) yr; body mass index, 23.9 (2.4) kg·m -2 ) completed four 2-d conditions (two control, two exercise) in randomized orders. On days 1 and 2, participants rested and consumed two high-fat meals over 9 h. Participants ran for 60 min (61 (7)% of peak oxygen uptake) on day 1 (6.5 to 7.5 h) of both exercise conditions. Time-averaged total area under the curve (TAUC) for triacylglycerol, glucose, and insulin were calculated from 11 venous blood samples on day 2. Arterial stiffness and blood pressure responses were calculated from measurements at baseline on day 1 and at 2.5 h on day 2. Consistency of individual differences was explored by correlating the two replicates of control-adjusted exercise responses for each outcome. Within-participant covariate-adjusted linear mixed models quantified participant-by-condition interactions and individual response SDs. RESULTS: Acute exercise reduced mean TAUC-triacylglycerol (-0.27 mmol·L -1 ·h; Cohen's d = 0.29, P = 0.017) and TAUC-insulin (-25 pmol·L -1 ·h; Cohen's d = 0.35, P = 0.022) versus control, but led to negligible changes in TAUC-glucose and the vascular outcomes (Cohen's d ≤ 0.36, P ≥ 0.106). Small-to-moderate, but nonsignificant, correlations were observed between the two response replicates ( r = -0.42 to 0.15, P ≥ 0.066). We did not detect any individual response heterogeneity. All participant-by-condition interactions were P ≥ 0.137, and all individual response SDs were small with wide 95% confidence intervals overlapping zero. CONCLUSIONS: Large trial-to-trial within-subject variability inhibited detection of consistent interindividual variability in postprandial metabolic and vascular responses to acute exercise.

Inconsistent Effect of Psychometric-Scale Familiarization on the Relationship Between Ratings of Perceived Exertion and External Load Measures in Elite Youth Soccer Players.

OBJECTIVES: To examine the moderating effect of familiarization on the relationship between external load and ratings of perceived exertion (RPEs) in elite youth soccer players. METHODS: Thirty-five elite male youth soccer players were monitored over a 31-week period. Players had no previous experience using the centiMax scale (arbitrary units [AU]). The final sample included familiarized (blackness test; n = 20) and nonfamiliarized players (n = 15) with the Borg centiMax scale. Players recorded a global RPE and differential RPEs (dRPE) for breathlessness (RPE-B) and leg-muscle exertion (RPE-L) 15 to 30 minutes following training sessions and competitive matches. Separate multivariable-adjusted random-effects generalized additive models with restricted maximum likelihood quantified familiarization versus no-familiarization differences in actual perceived exertion score (in AU) by number of accelerations, decelerations, and high-speed running distance (in meters) as predictor variables, respectively. RESULTS: Players improved their blackness test score from 39% to 78%. For explorations by number of accelerations, familiarization effects were not practically relevant for the RPE and RPE-B variables. The width and sign of the effects for the RPE-L variable at 30 efforts of 10 AU (95% CI, 4-16 AU) suggested that scores were lower for players who underwent familiarization versus players who did not. Familiarization effects were not practically relevant for any RPE variable irrespective of the number of deceleration efforts and high-speed running distance covered. CONCLUSION: Improved performance on the blackness test did not have a moderating effect on the relationship between proxy measures of external load and RPEs.

Age-Related Reference Intervals for Physical Performance Test Outcomes Relevant to Male Youth Middle Eastern Football Players.

PURPOSE: To develop age-specific reference intervals for physical performance test outcomes relevant to male youth Middle Eastern football players. METHODS: We analyzed mixed-longitudinal data (observations range: 1751-1943 assessments) from a sample of 441 male youth outfield football players (chronological age range: 11.7-18.4 y) as part of the Qatar Football Association and Aspire Academy development program over 14 competitive seasons. Semiparametric generalized additive models for location, scale, and shape estimated age-specific reference centiles for 10-m sprinting, 40-m sprinting, countermovement jump height, and maximal aerobic speed variables. RESULTS: The estimated reference intervals indicated that the distribution of the physical performance test scores increased monotonically and nonlinearly with advancing chronological age for sprinting and countermovement jump outcome measures, reaching a plateau after 16 years common to each of these performance variables. The maximal aerobic speed median score increased substantially until ∼14.5 years, with the nonlinear trend flattening off toward relatively older chronological ages. CONCLUSIONS: We developed age-related reference intervals for physical performance test outcomes relevant to youth Qatari football players. Country-wide age-specific reference intervals can assist in the longitudinal tracking of the individual players' progress over time against benchmark values derived from the reference population.

A comparison of FELS and Tanner-Whitehouse II skeletal ages in male youth soccer players from the Middle East.

OBJECTIVES: To assess measurement agreement between FELS and Tanner-Whitehouse (TW) II skeletal ages in male youth soccer players from the Middle East. METHODS: We examined agreement between FELS and TW-II skeletal ages using data collected between- and within-subjects (n = 1057 observations) for 409 male, full-time, academy student-athletes recruited as part of the Qatar Football Association national soccer development programme (chronological age range, 9.8 to 18 years; annual screening range, one to seven visits). The Bland-Altman method for repeated measurements estimated the limits of agreement describing the expected range of differences for 95% of pairs of future FELS and TW-II skeletal ages determined on similar individuals from the reference population. RESULTS: The mean difference for TW-II versus FELS protocols was 0.02 years (95% confidence interval, -0.04 to 0.08 years) with lower and upper limits of agreement ranging from -1.39 years (95% confidence interval, -1.48 to -1.30 years) to 1.43 years (95% confidence interval, 1.34 to 1.52 years). CONCLUSION: Differences for 95% of pairs of future skeletal ages determined with FELS and TW-II methods in this population could be as high as ~3 years for some people that suggested protocols may not be interchangeable in youth Middle Eastern athletes. Justification of skeletal age protocol selection rests on knowledge of measurement bias and variability of expected growth estimations for rationalized application to a population of interest.

Skeletal maturation in male elite youth athletes from the Middle East.

OBJECTIVES: To examine the timing and intensity of skeletal maturation of the radius-ulna-short (RUS) bones in elite youth Arab athletes. METHODS: We compared SuperImposition by Translation And Rotation (SITAR) models with different spline degrees of freedom and transformation expressions to summarize 492 longitudinal measurements for individual RUS bones scores assessed from 99 male academy student-athletes (chronological age range, 11.4 to 18 years; annual screening range, four to seven visits). RESULTS: The SITAR model with 5 degrees of freedom and untransformed chronological age was superior to the other models. The mean growth curve increased with age and showed a mid-pubertal double-kink at a RUS score of ~600 bone score units (au). The SITAR model revealed a first peak in the skeletal maturation velocity curve of ~206 au·year-1 occurred at ~13.5 years. The mean age at the second and largest peak occurred at 15.1 years (95% confidence interval [CI], 14.9 to 15.3 years), with the respective estimated peak skeletal ossification rate of 334 au·year-1 (95% CI, 290 to 377 au·year-1 ). The mean age at peak height velocity was 13.5 years (95% CI, 13.3 to 13.7 years), with peak height velocity of 10 cm·year-1 (95% CI, 9.6 to 10.4 cm·year-1 ). CONCLUSION: Application of the SITAR method confirmed two peaks in the skeletal maturation velocity curve, with the second and largest rate of ossification occurring at a relatively later timing of ~1.5 years than the height growth spurt. Knowledge of the RUS bones timing and intensity can be important to advance strategies for athlete performance development purposes.

The Percentage of Mature Height as a Morphometric Index of Somatic Growth: A Formal Scrutiny of Conventional Simple Ratio Scaling Assumptions.

PURPOSE: To assess conventional assumptions that underpin the percentage of mature height index as the simple ratio of screening height (numerator) divided by actual or predicted adult height (denominator). METHODS: We examined cross-sectional data from 99 academy youth soccer players (chronological age range, 11.5 to 17.7 y) skeletally immature at the screening time and with adult height measurements available at follow-up. RESULTS: The y-intercept value of -60 cm (95% confidence interval, -115 to -6 cm) from linear regression between screening height and adult height indicated the failure to meet the zero y-intercept assumption. The correlation coefficient between present height and adult height of .64 (95% confidence interval, .50 to .74) was not equal to the ratio of coefficient of variations between these variables (CVx/CVy = 0.46) suggesting Tanner's special circumstance was violated. The non-zero correlation between the ratio and the denominator of .21 (95% confidence interval, .01 to .39) indicated that the percentage of mature height was biased low for players with generally shorter adult height, and vice versa. CONCLUSION: For the first time, we have demonstrated that the percentage of mature height is an inconsistent statistic for determining the extent of completed growth, leading to potentially biased inferences for research and applied purposes.

Perspectives on Postmatch Fatigue From 300 Elite European Soccer Players.

PURPOSE: To examine the general perspectives of elite soccer players on the time course of perceived postmatch fatigue and the influence of away matches on subjective perceptions. METHODS: Adopting a cross-sectional study design, we invited 371 subjects from 14 top-division European clubs competing in the Belgian First Division A, English Premier League, French Ligue 1, Italian Serie A, Portuguese Primeira Liga, Russian Premier League, and Swiss Premier League to take part in a short survey on general issues relating to postmatch fatigue measurement and tracking in professional soccer. RESULTS: Three hundred male professional soccer players completed the short questionnaire. For perceptions relevant to the time course of postmatch fatigue, two-thirds of respondents (67%) indicated higher postmatch fatigue perceived 2 days (48 h) after an official competition. Among these respondents, a higher proportion of answers was observed in wide midfielders (74%), attackers (74%), and central midfielders (68%). Approximately two-thirds of respondents (63%) indicated more than usual and much more than usual perceived postmatch fatigue following away matches. CONCLUSIONS: For the first time, our investigation addressed practical aspects that remained unexplored and fundamental to the definition of an optimal player management process following a competition. From a practical standpoint, perspectives of individual elite soccer players substantiated the notion of implementing processes with dedicated recovery protocols within 48 hours postmatch and highlighted the need for differential strategies addressing the additional burden of away matches and travel.

A survey of organizational structure and operational practices of elite youth football academies and national federations from around the world: A performance and medical perspective.

Aim: Medical and performance units are integral components of player development programmes in elite football academies. Nevertheless, the nature of the operational processes implemented by practitioners within clubs and national federations remains unexplored. The aim of the present study, therefore, was to survey elite youth professional football academies from around the world regarding the operational processes adopted by their medical and performance units. Methods: Of the 50 organizations invited, 10 national federations and 25 clubs took part in the survey resulting in a response rate of 70% (95% confidence interval, 56%-81%). The respondents represented three groups: senior club and academy management, performance, and medical staff. Results: The majority (60%-90%) of clubs and national federations reported strategic alignment between senior and academy medical and performance units as well as between academy medical and performance units. Survey responses indicated substantial heterogeneity in the composition and number of medical and performance professionals employed in academies. The majority of respondents agreed their medical and performance departments were effective in utilizing staff knowledge and external sources of knowledge to inform their practice (56%-80%). Performance staff (40%-50%) and physiotherapists (30%-32%) were deemed most influential in injury prevention programmes. During the return-to-play process, the influence of specific practitioners in the medical and performance units was dependent upon the phase of return-to-play. Shared decision-making was common practice amongst performance and medical staff in injury prevention and return-to-play processes. Medical and performance data were generally centralized across the first team and academy in majority (50%-72%) of clubs and national federations. Data were integrated within the same data management system to a higher degree in clubs (68%) vs. national federations (40%). Research and development activity were reported for most academies (50%-72%), and generally led by the head of performance (37%) or team doctor (21%). Research activities were largely undertaken via internal staff (~100%), academic collaborations (50%-88%) and/or external consultants and industry partnerships (77%-83%) in the national federation and clubs. Conclusion: Collectively, these findings provide a detailed overview regarding key operational processes delivered by medical and performance practitioners working in elite football academies.

High-speed running during match-play before and after return from hamstring injury in professional footballers.

Hamstring injuries constitute the single largest cause of lost playing time in professional football. While restoring high-speed running ability is paramount for rehabilitation from these injuries, little evidence exists regarding the extent of return to sport running performance after hamstring injury in football. We examined medical and match performance data available from a sample of 38 professional soccer players competing in the Qatar Stars League (N = 1426 observations) to describe high-speed running performance during match-play prior and subsequent to a hamstring strain injury. Multivariable-adjusted random-effects generalized additive models estimated post- versus pre-hamstring injury differences in maximal speed (km/h), high-speed running (>20 km/h), and sprinting (>25 km/h) distance. Mean effects and uncertainty (95% confidence interval, CI) were interpreted against the estimated random match-to-match variability in maximal sprinting speed, high-speed running distance, and sprinting running distance of ±1.67 km/h (95% CI, 1.62-1.72 km/h), ±102 m (95% CI, 99-105 m), and ±60 m (95% CI, 58-61 m), respectively. The estimated post- versus pre-hamstring injury mean differences in maximal sprinting speed, high-speed running distance, and sprinting running distance primary outcomes were -0.25 km/h (95% CI, -0.38 to -0.12 km/h), -43 m (95% CI, -56 to -30 m), and -22 m (95% CI, -29 to -16 m). Players returning to football match-play after hamstring strain injury experienced reductions in high-speed match physical performance that were well within normal match-to-match variation in performance.

Inter-methodological quantification of the target change for performance test outcomes relevant to elite female soccer players.

INTRODUCTION: Valid and informed interpretations of changes in physical performance test data are important within athletic development programmes. At present, there is a lack of consensus regarding a suitable method for deeming whether a change in physical performance is practically relevant or not. METHODS: We compared true population variance in mean test scores between those derived from evidence synthesis of observational studies to those derived from practioner opinion (n = 30), and to those derived from a measurement error (minimal detectable change) quantification (n = 140). All these methods can help to obtain 'target' change score values for performance variables. RESULTS: We found that the conventional 'blanket' target change of 0.2 (between-subjects SD) systematically underestimated practically relevant and more informed changes derived for 5-m sprinting, 30-m sprinting, CMJ, and Yo-Yo Intermittent Recovery Level 1 (IR1) tests in elite female soccer players. CONCLUSIONS: For the first time in the field of sport and exercise sciences, we have illustrated the use of a principled approach for comparing different methods for the definition of changes in physical performance test variables that are practically relevant. Our between-method comparison approach provides preliminary guidance for arriving at target change values that may be useful for research purposes and tracking of individual female soccer player's physical performance.

Relative Skeletal Maturity and Performance Test Outcomes in Elite Youth Middle Eastern Soccer Players.

PURPOSE: This study aimed to explore the influence of differences in relative skeletal maturity on performance test outcomes in elite youth soccer players from the Middle East. METHODS: We integrated skeletal age and performance assessments using mixed-longitudinal data available for 199 outfield players (chronological age range, 11.7 to 17.8 yr) enrolled as academy student-athletes (annual screening range, 1 to 5 visits). Skeletal age was determined as per the Tanner-Whitehouse II protocol. Relative maturity was calculated as the difference (∆) between Tanner-Whitehouse II skeletal age minus chronological age. Performance test outcomes of interest were 10-m sprinting, 40-m sprinting, countermovement jump height, and maximal aerobic speed. Separate random-effects generalized additive models quantified differences in performance test outcomes by relative skeletal maturity. Estimated differences were deemed practically relevant based on the location of the confidence interval (95% CI) against minimal detectable change values for each performance test outcome. RESULTS: For 40-m sprinting, differences of +0.51 s (95% CI, +0.35 to +0.67 s) and +0.62 s (95% CI, +0.45 to +0.78 s) were practically relevant for relative maturity status of ∆ = -1.5 yr versus ∆ = +0.5 and ∆ = +1 yr, respectively. For countermovement jump height, a difference of -8 cm (95% CI, -10 to -5 cm) was practically relevant for ∆ = -1.5 yr versus ∆ = +1 yr relative maturity status comparison. Effects for 10-m sprinting and maximal aerobic speed were unclear. CONCLUSIONS: Integration of skeletal age and performance assessments indicated that conventional maturity status classification criteria were inconsistent to inform player development processes in our sample. Between-player differences in test performance may depend on a substantial delay in skeletal maturation (∆ ≤ -1.5 yr) and the performance outcome measure.