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What is single-case research? How can single-case methods be used within sport and exercise? Single-case research is a powerful method for examining change in outcome variables such as behaviour, performance and psychological constructs, and for assessing the efficacy of interventions. It has innumerable uses within the context of sport and exercise science, such as in the development of more effective performance techniques for athletes and sportspeople and in helping us to better understand exercise behaviours in clinical populations. However, the fundamental principles and techniques of single-case research have not always been clearly understood by students and researchers working in these fields. Single-Case Research Methods in Sport and Exercise Psychology is the first book to fully explain single-case research in the context of sport and exercise. Starting with first principles, the book offers a comprehensive introduction to the single-case research process, from study design to data analysis and presentation. Including case studies and examples from across sport and exercise psychology, the book provides practical guidance for students and researchers and demonstrates the advantages and common pitfalls of single-case research for anybody working in applied or behavioural science in a sport or exercise setting.

Sport science practitioners utilise findings from peer reviewed research to inform practice. Fewer studies are conducted with high performance athletes, however, than those involving recreationally active participants. Noting that research findings from recreational athletes may not be generalisable to the elite, there is a need to engage the latter cohort in research with better potential to influence health and performance. This study identified methods used to engage and recruit highly trained, elite and world class athletes as research participants. A document analysis was conducted using a purposive sample of peer‐reviewed sport science literature. All articles published in 2022 from 18 highly ranked sport science journals were screened for inclusion. Studies investigating athletes ranked as highly trained/national level or above were included. All details related to participant recruitment were extracted from included articles, with the content being coded and thematically analysed using an interpretivist approach. A total of 439 studies from the 2356 screened were included in the analysis. Five primary themes of recruitment strategies were identified, beneath an overarching strategy of purposeful, convenience sampling. Recruitment themes related to the use of a gatekeeper, the research environment providing convenient access to athletes, promoting the study electronically, utilising professional networks and recruiting at training or competition. Engaging athletes through a gatekeeper is a prominent strategy to involve elite athletes in research. It is suggested that researchers work collaboratively with team or organisation personnel to promote recruitment, creating co‐designed approaches that address issues most relevant to athletes and staff. Highlights Engaging elite athletes through a gatekeeper appears to be a successful strategy for participant recruitment. Embedding a researcher within the sporting organisation or team, or collaborating with team personnel, are two possible approaches to using a gatekeeper and will likely promote recruitment as well as the co‐design of sport science research. Taking advantage of the university environment where student‐athletes are available is a convenient and potentially effective approach to engaging athletes for recruitment.

The physical demands of elite soccer match play have traditionally been measured using aggregated whole‐match metrics. However, match play is increasingly considered as distinct phases of play, although the influence of phase of play on match physical demands remains largely unknown. This study compared physical intensity, acceleration and deceleration demands, between phases of play and according to playing position. The duration of each match from a major European league (n = 1083) was divided into one of five reciprocal phases (for the in‐/out‐of‐possession team) using event and tracking data: build‐up/high‐block, progression/mid‐block, chance creation/low‐block, fast attack/fast defence, or attacking transition/defensive transition. Player tracking data were used to calculate physical intensity as the rate of distance covered (m⋅min−1) in total and within five speed categories, and the proportion of time spent accelerating and decelerating (>2 m s−2) during each phase of play. Rate of distance covered in total differed markedly with phase of play; fast attack 35%–53% greater, and fast defence 33%–50% greater, than other in‐/out‐of‐possession phases respectively, and these effects were amplified for the rate of distance covered at higher speeds (e.g., sprinting ≥4‐fold differences between phases). Match phase also affected the proportion of time spent accelerating and decelerating (highest for fast attack and chance creation, respectively), especially when in‐possession for forwards and when out‐of‐possession for defenders (p < 0.001). Phase of play had a large effect on the physical intensity of match play, particularly rates of distance covered at higher speeds, as well as the acceleration and deceleration demands, and in a position specific manner. Highlights Despite elite soccer match play being increasingly considered as distinct phases of play, the effect of phase on physical metrics is largely unknown. This analysis of 1083 matches of a major European league found rates of distance covered in total, as an index of physical intensity, differed markedly (by >50%) according to phase, with even more pronounced effects on the rates of distance covered at higher speeds (e.g., sprinting >4‐fold greater for fast attack and fast defence than some phases). Playing position also had a pronounced interaction with phase of play; fast attack (forwards) and fast defence (midfielders and defenders) phases involving considerably greater physical intensities. Moreover, phase of play also had a large effect on the proportion of time spent accelerating and decelerating, most notably when in‐possession for forwards and when out‐of‐possession for defenders. Thus, the present study is the first to comprehensively divide the entire duration of match play into distinct phases using event and tracking data, demonstrating that match physical demands during elite soccer match play are extensively effected by match phase, and in a position specific manner.

It has been suggested that time at a high fraction (%) of maximal oxygen uptake (VO2max) plays a decisive role for adaptations to interval training. Yet, no study has, to date, measured the % of VO2max during all interval sessions throughout a prolonged training intervention and subsequently related it to the magnitude of training adaptations. Thus, the present study aimed to investigate the relationship between % of VO2max achieved during an interval training intervention and changes in endurance performance and its physiological determinants in well‐trained cyclists. Twenty‐two cyclists (VO2max 67.1 (6.4) mL·min−1 ·kg−1; males, n = 19; females, n = 3) underwent a 9‐week interval training intervention, consisting 21 sessions of 5 × 8‐min intervals conducted at their 40‐min highest sustainable mean power output (PO). Oxygen uptake was measured during all interval sessions, and the relationship between % of VO2max during work intervals and training adaptations were investigated using linear regression. A performance index was calculated from several performance measures. With higher % of VO2max during work intervals, greater improvements were observed for maximal PO during the VO2max test (R2adjusted = 0.44, p = 0.009), PO at 4 mmol·L−1 [blood lactate] (R2adjusted = 0.25, p = 0.035), the performance index (R2adjusted = 0.36, p = 0.013), and VO2max (R2adjusted = 0.54, p = 0.029). Other measures, such as % of maximal heart rate, were related to fewer outcome variables and exhibited poorer session‐to‐session repeatability compared to % of VO2max. In conclusion, improvements in endurance measures were positively related to the % of VO2max achieved during interval training. Percentage of VO2max was the measure that best reflected the magnitude of training adaptations. Highlights In the present study, we measured well‐trained cyclists' oxygen uptake during 21 power output‐matched interval sessions throughout a 9‐week training intervention and related it to the magnitude of training adaptations. For the first time, we demonstrate that gains in endurance measures following an interval training intervention are positively related to the fraction of maximal oxygen uptake (V̇O2max) and time spent ≥90% of V̇O2max during interval sessions. Fraction of V̇O2max during sessions demonstrated better session‐to‐session repeatability and displayed stronger associations with improvements in indicators of endurance performance compared to the percentage of maximal heart rate.

The study aimed to illustrate how contact (from match‐event data) and head acceleration event (HAE) (from instrumented mouthguard [iMG]) data can be combined to inform match limits within rugby. Match‐event data from one rugby union and rugby league season, including all competitive matches involving players from the English Premiership and Super League, were used. Playing exposure was summarised as full game equivalents (FGE; total minutes played/80). Expected contact and HAE exposures at arbitrary thresholds were estimated using match‐event and iMG data. Generalised linear models were used to identify differences in contact and HAE exposure per FGE. For 30 FGEs, forwards had greater contact than backs in rugby union (n = 1272 vs. 618) and league (n = 1569 vs. 706). As HAE magnitude increased, the differences between positional groups decreased (e.g., rugby union; n = 34 and 22 HAE >40 g for forwards and backs playing 30 FGEs). Currently, only a relatively small proportion of rugby union (2.5%) and league (7.3%) players exceeded 25 FGEs. Estimating contact and HAEs per FGE allows policymakers to prospectively plan and model estimated overall and position‐specific loads over a season and longer term. Reducing FGE limits by a small amount would currently only affect contact and HAE exposure for a small proportion of players who complete the most minutes. This may be beneficial for this cohort but is not an effective HAE and contact exposure reduction strategy at a population level, which requires individual player management. Given the positional differences, FGE limits should exist to manage appropriate HAE and contact exposure. Highlights Estimating contact events and head acceleration events (HAEs) per full game equivalents (FGE, i.e., 80 minutes) allows policymakers to prospectively plan and model estimated overall and position‐specific loads over a season and longer term. Through retrospectively analysing FGE exposure, the findings demonstrate that only a small proportion of rugby players would be affected by a feasible reduction in FGE limits, but the difference in contact and HAE exposure for these players could be significant over the duration of a playing career. Per FGE in both rugby codes, forwards have a greater expected contact and head acceleration event exposure than backs, and thus any implemented FGE limits should at least be position group‐specific and ideally incorporate individual player management.

Endurance athletes fail to meet carbohydrate (CHO) guidelines for competition, which may be due to limited knowledge. However, the relationship between knowledge and practice in this population is unknown. To investigate this, we assessed the dietary intake in 50 athletes (37 females) who completed endurance events ≥2.5 h in duration and compared CHO intake against the carbohydrates for endurance athletes in competition questionnaire validated nutrition knowledge questionnaire, with specific questions related to CHO loading, pre‐competition meal and during‐competition intake. CHO‐loading guidelines (10–12 g · kg−1 · day−1) were met in practice by n = 5 (10%), but there was no relationship between identified requirements (range 0–12 g · kg−1 · day−1) and actual intake (rs = 0.133, p = 0.358), with the n = 18 (36%) who correctly identified requirements, ingesting 6.1 ± 1.9 g · kg−1 · day−1. CHO intake for pre‐competition meal guidelines (1–4 g · kg−1) was met in practice by n = 40 (80%), but there was no relationship between identified requirements (range 0 to >4 g · kg−1) and actual intake (rs = 0.101, p = 0.487), with n = 19 (38%) who correctly identified guidelines requirements, ingesting 1.4 ± 0.6 g · kg−1. CHO intake during‐competition guidelines (60–90 g · h−1) was met in practice by n = 18 (36%), but there was no relationship between the amounts of CHO required (range 30 to >90 g/h) and actual intake (rs = 0.028, p = 0.849), with n = 32 (64%) who correctly identified guidelines requirements, ingesting 56 ± 20 g · h−1. Results show no relationship between the knowledge of CHO recommendations and practice, suggesting that theoretical knowledge does not guarantee the achievement of best practice and other important factors may ultimately determine practice. Highlights The carbohydrates for endurance athletes in competition questionnaire (CEAC‐Q) score did not show any association between theoretical knowledge and actual intake for carbohydrate (CHO) loading, pre‐competition, or during competition scenarios, indicating that athletes do not necessarily apply what they know. Despite 30% of athletes meeting the guidelines for CHO loading, and CHO intake during competition, there was no clear relationship between practice and their knowledge of these guidelines as measured by the CEAC‐Q. The discrepancy between theoretical knowledge and actual intake within real‐world competition highlights that other factors may be important barriers and facilitators to translate scientific knowledge and bridge the gap into optimal dietary practices of endurance athletes.

We examined the sensitivity and time‐course of recovery of neuromuscular and perceptual player monitoring measures to U‐18 English Premier League academy football match play. Eighteen players performed maximal posterior chain, hip adductor and abductor isometric strength tests, countermovement jumps (CMJ) and provided self‐report wellbeing scores around eight competitive league home games: 1 day before (MD‐1), pre‐match (MD‐PRE), post‐match (MD‐POST) and two (MD+2) and three (MD+3) days post‐match. A permutational multivariate analysis of variance and post hoc univariate analyses of variance were used to examine match‐induced responses to monitoring variables. Between MD‐1 and MD‐POST, we observed small to moderate reductions to the adductor and abductor peak force and maximal impulse and IPCS peak force; small reductions to CMJ jump height (JH) (flight time), eccentric peak force and eccentric deceleration rate of force development and moderate to large reductions to perceived fatigue, muscle soreness and mood. No match‐induced changes were observed for CMJ flight time: contraction time or eccentric duration. Posterior chain, abductor, CMJ and self‐report measures normalised by MD+3 but adductor peak force remained compromised at MD+3 (ES = small). Posterior chain, adductor and abductor peak isometric force and maximal impulse; CMJ JH, eccentric peak force and eccentric deceleration rate of force development and perceived fatigue, muscle soreness and mood are sensitive to match‐induced fatigue. Since adductor peak force remained compromised at MD+3, it is apparent that players might not achieve complete neuromuscular recovery within 3 days of match play, and that the adductor muscle group might be particularly vulnerable to match‐induced fatigue. Highlights U‐18 English Premier League (EPL) academy football match play induced acute reductions to countermovement jump (jump height [flight time], eccentric peak force and eccentric deceleration rate of force development); isometric strength (abductor, adductor and posterior chain peak force and abductor and adductor maximal impulse) and athlete self‐report (perceived fatigue, muscle soreness and mood) measures. Match‐induced changes to countermovement jump, abductor, posterior chain and self‐report measures typically normalised between MD+2 and MD+3 but adductor peak force remained compromised at MD+3. No meaningful match‐induced changes were observed to widely used countermovement jump movement strategy measures (i.e., flight time: contraction time ratio or eccentric duration). U‐18 EPL academy football players might not achieve complete neuromuscular recovery by MD+3. The adductor muscle group might be particularly susceptible to match‐induced fatigue.

Ultrarunning is gaining in popularity but no information is available on the physiological and psychological responses during backyard ultrarunning events. The aim of this study was to determine changes in cognitive function, markers of physiological resilience, and running performance during a backyard‐running event. Twelve male ultrarunners (38 ± 8 years old, BMI: 23.5 ± 1.6 kg/m2, and VO2max: 60.8 ± 4.7 mL/min/kg) were monitored before, during, and after the event. Cognitive performance was determined using a cognitive test battery before, during, and after the event. During the event, the rating of perceived exertion (RPE), blood lactate concentration, and heart rate (HR) were assessed. Physical performance was investigated using the total number of completed laps and running speed per lap. Athletes completed 34 ± 17 laps equaling 227.8 ± 113.9 km with average speeds starting at 9.0 km/h and slowing down to 7.5 km/h at the end of the event. Physiological resilience (estimated using HR/speed) varied between athletes, with significantly lower values in the more proficient backyard runners at the end of the event (p < 0.05). HR and lactate levels remained constant, whereas a progressive increase in RPE was noticed (p ≤ 0.001). A significantly worsened reaction time was observed for several cognitive tasks after the event compared to baseline measures (p ≤ 0.05). These observations show that physiological resilience differs depending on the level of endurance performance of the athletes. Furthermore, the backyard ultrarunning event negatively impacted psychomotor speed. Therefore, the results suggest that implementing strategies that enhance physiological resilience and/or psychomotor speed could potentially have a positive effect on performance in ultraendurance activities. Highlights Backyard running events showcase varying physiological resilience, emphasizing its role in differentiating top‐performing athletes. Pacing dynamics and cognitive decline during ultraendurance events highlight the complex interplay between physical and mental fatigues. Exploring resilience and cognitive functioning during ultraendurance events is important for optimizing training and other interventions in extreme endurance challenges.

The study explores the validity of the nonlinear index alpha 1 of detrended fluctuation analysis (DFAa1) of heart rate (HR) variability for exercise prescription in prolonged constant load running bouts of different intensities. 21 trained endurance athletes (9 w and 12 m) performed a ramp test for ventilatory threshold (vVT1 and vVT2) and DFAa1‐based (vDFAa1‐1 at 0.75 and vDFAa1‐2 at 0.5) running speed detection as well as two 20‐min running bouts at vDFAa1‐1 and vDFAa1‐2 (20‐vDFAa1‐1 and 20‐vDFAa1‐2), in which HR, oxygen consumption (VO2), respiratory frequency (RF), DFAa1, and blood lactate concentration [La‐] were assessed. 20‐vDFAa1‐2 could not be finished by all participants (finisher group (FG), n = 15 versus exhaustion group (EG), n = 6). Despite similar mean external loads of vDFAa1‐1 (10.6 ± 1.9 km/h) and vDFAa1‐2 (13.1 ± 2.4 km/h) for all participants compared to vVT1 (10.8 ± 1.7 km/h) and vVT2 (13.2 ± 1.9 km/h), considerable differences were present for 20‐vDFAa1‐2 in EG (15.2 ± 2.4 km/h). 20‐vDFAa1‐1 and 20‐DFAa1‐2 yielded significant differences in FG for HR (76.2 ± 5.7 vs. 86.4 ± 5.9 %HRPEAK), VO2 (62.1 ± 5.0 vs. 77.5 ± 8.6 %VO2PEAK), RF (40.6 ± 11.3 vs. 46.1 ± 9.8 bpm), DFA‐a1 (0.86 ± 0.23 vs. 0.60 ± 0.15), and [La‐] (1.41 ± 0.45 vs. 3.34 ± 2.24 mmol/L). Regarding alterations during 20‐vDFAa1‐1, all parameters showed small changes for all participants, while during 20‐vDFAa1‐2 RF and DFAa1 showed substantial alterations in FG (RF: 15.6% and DFAa1: −12.8%) and more pronounced in EG (RF: 20.1% and DFAa1: −35.9%). DFAa1‐based exercise prescription from incremental testing could be useful for most participants in prolonged running bouts, at least in the moderate to heavy intensity domain. In addition, an individually different increased risk of overloading may occur in the heavy to severe exercise domains and should be further elucidated in the light of durability and decoupling assessment. Highlights DFAa1‐based exercise prescription from incremental testing shows potential for prolonged constant load exercise, at least in the moderate to heavy intensity domains for most trained runners. Caution is advised for the heavy to severe exercise domains as individual overload may occur. The relationship of DFAa1 and vDFAa1 seems to be highly individual as well as perspectives for the durability and decoupling assessment and should be further elucidated during longer exercise bouts.

Nine cyclists (age: 26 ± 5 years, height: 168 ± 5 cm and mass 58.5 ± 4.5 kg) were observed using continuous glucose monitoring devices throughout a training camp. Interstitial glucose [iG] data were captured via the Abbott libre sense biosensor (Abbott Laboratories) and paired with the Supersapiens software (TT1 Products Inc.). [iG] data were split into time ranges, that is, overall (24‐hourly), day‐time (06:00–23:59), night‐time (00:00–05:59) and exercise. [iG] data were stratified into percentage of time, below range ([TBR] < 70 mg/dl), in range ([TIR] 70–140 mg/dl) and above range ([TAR] ≥ 141 mg/dl). Differences in diurnal and nocturnal data were analysed via repeated measures analysis of variance and paired t‐tests where appropriate. p‐value of ≤0.05 was accepted as significant. Riders spent an average of 3 ± 1% TAR, 93 ± 2% TIR and 8 ± 3% TBR. Mean 24 h [iG] was 93 ± 2 mg/dl with a coefficient of variation (CV) of 18 ± 1%. Mean (day: 95 ± 3 vs. night: 86 ± 3 mg/dl and p < 0.001) and CV (day: 18 ± 1 vs. night: 9 ± 1% and p < 0.001) in [iG] were higher during the day‐time hours. TAR was greater during the day (day: 3 ± 1 vs. night: 0 ± 0% and p < 0.001) but TBR and TIR were similar. Glucose levels below the clinical range may have implications for those without diabetes and warrants further investigation. Highlights The data provided in this study offer novel insight into the daily glycaemic responses of female cyclists engaged in consecutive days' worth of heavy exercise training as part of a performance camp. % Time above range was greatest during exercise whereas, the % time below range was at its lowest. This may offer some insight into the demands of exercise and glucose variability. Riders maintained a high percentage of time spent in range, yet displayed some time <70 mg/dl, that is, hypoglycaemia. A proportionate amount of time was spent with glucose levels below the clinical range, the potential health and/or sports performance implications of this in athletic individuals without diabetes warrants further investigation.