Impact of temperature on physical and cognitive performance in elite female football players during intermittent exercise.

There is limited research on female football players, especially related to their physical and cognitive performance under different climactic conditions. We analyzed the impact of a hot environmental temperature on physical performance and anticipation in elite female football players during a fatigue-inducing intermittent protocol. Elite female players (n = 21) performed the countermovement jump (CMJ) and responded to filmed sequences of offensive play under two distinct environmental temperatures (i.e., mild environment temperature- 20°C and 30% rh versus hot environment temperature- 38°C and 80% rh), interspersed by 1-week interval. Linear mixed models were used. CMJ performance declined following the intermittent protocol on both temperature conditions (p < 0.05). Moreover, there were significant main effects for protocol on CMJ speed (m/s) (p = 0.001; ηp 2 = 0.12), CMJ power (p = 0.002; ηp 2 = 0.11), and CMJ Heightmax (p = 0.002; ηp 2 = 0.12). After performing the intermittent protocol, exposure to a hot temperature caused a greater decline in anticipation accuracy (mild temperature = 64.41% vs. hot temperature = 53.44%; p < 0.001). Our study shows impaired performance in elite female football players following an intermittent protocol under hot compared with mild environmental conditions. We report decreased performance in both CMJ and anticipation performance under hotter conditions. The results reveal that exposure to hot temperatures had a negative effect on the accuracy of their anticipatory behaviors. We consider the implication of the work for research and training interventions.

A school-based physical activity intervention in primary school: effects on physical activity, sleep, aerobic fitness, and motor competence.

Objective: The "Super Quinas" project evaluated the effectiveness of an intervention program to improve physical activity, aerobic fitness, sleep, and motor competence on children in primary school. Methods: The experimental group (n = 19) enrolled in a 12-week intervention program (one more extra-curricular activity class of 60 min per week) compared to the CG (n = 19), all aged 9-10 years. Physical activity (PA) and sleep were measured by accelerometry, and aerobic fitness was measured by Children's Yo-Yo test (YYIR1C) during the 1st week (PRE), the 6th week (DUR), and the 12th week (POST) of the intervention program. Motor Competence in PRE and POST intervention was also assessed by the Motor Competence Assessment (MCA) instrument. Heart rate (HR, assessed using HR monitors), and enjoyment level were recorded during all intervention program classes. A linear mixed model analysis (i.e., within-subject analyses) was performed. Results: Comparing the EG and CG in DUR and POST, the EG spent ~18 min and ~ 34 min more time in moderate to vigorous physical activity (MVPA) per day (p < 0.001); had ~44 min and ~ 203 min less sedentary time per day (p < 0.001); performed more 44 and 128 m in the Children's Yo-Yo test compared to CG (p < 0.001) and slept more 17 and 114 min per night (p < 0.001). In POST motor competence was significantly better (27%) in the EG compared to CG (p < 0.001). The %HRmax during the extra-curricular classes ranged between 65 and 81% (i.e., light to moderate intensities), and the enjoyment between fun and great fun. Conclusion: Our findings suggest that adding one more extra-curricular activity class of 60 min per week for 12 weeks effectively increased the levels of physical activity, aerobic fitness, sleep duration, and motor competence in children aged 9-10 years.

Sleep duration is associated with overnight changes in perceived fatigue in elite women soccer players.

The current study aimed to describe sleep habits and analyze the associations between sleep indices, changes in perceived fatigue (Δ Fatigue) and external training load measures in women soccer players during a 7-day training camp. Sixteen elite women soccer players (age: 25.4 ± 3.6 years; mean ± SD) from the Portuguese Women's National Team participated in the study. Sleep indices (sleep duration and efficiency) were measured using a wrist-worn accelerometer. External training loads measures were measured using GPS devices. Players also reported perceived fatigue using a Likert scale (1 - very, very low to 7 - very, very high) before and immediately after sleep. Players' within-subject coefficient of variation for sleep duration was 5.6%, and 4.6% for sleep efficiency. Individually, 8 players (50%) slept less than 7 h per night throughout the training camp, and the same number of athletes had a sleep efficiency lower than 85%. Similar values (p<0.05) were measured for sleep duration and efficiency between training and match days. A moderate negative within-subjects correlation was found between Δ Fatigue and sleep duration (adjusted for pre-sleep fatigue) [r = -0.32; 95% Confidence Interval (-0.51 - -0.08); p = 0.04]. These findings reinforce the importance of sleep in the recovery process of elite women soccer players, showing that more sleep may help to attenuate fatigue.

Simulated Soccer Game Protocols: A Systematic Review on Validated Protocols That Represent the Demands of the Game.

ABSTRACT: Brito, P, Costa, J, Figueiredo, P, and Brito, J. Simulated soccer game protocols: A systematic review on validated protocols that represent the demands of the game. J Strength Cond Res 38(1): 192-205, 2024-Several laboratory and field testing protocols have been developed attempting to simulate the activity pattern and physiological demands of soccer. In the present systematic review, we aimed to analyze and discuss the appropriateness, strengths, and limitations of soccer-specific simulated tests. A systematic review of the literature was conducted based on the PRISMA guidelines. Studies conducted in soccer, simulated soccer match tests, and validated simulation protocols performed on-the-field or on a treadmill were considered. No sex restriction was applied, and age >18 years (i.e., adults) was considered. At least 1 outcome measure (e.g., neuromuscular performance, external load, internal load, or psychometric state) of post-simulated-match test or protocol had to be reported. Within the 14 studies included, the average methodological quality of the included articles was 0.61 ± 0.09 (mean ± SD) of 1. Overall, 9 validated protocols were identified. In the protocols, only amateur, university, or semiprofessional soccer players were analyzed. Only one study evaluated female soccer players. None of the studies evaluated the effect on performance over the 2-3 days after the protocol. Accelerations and decelerations, and changes in direction typically present in a game have not been clearly described in any protocol. Future research should address this issue and validate soccer-specific protocols in women.

Effects of "Football and Nutrition for Health" program on body composition, physical fitness, eating behaviours, nutritional knowledge, and psychological status among 7 to 10 years school children.

Introduction: Noncommunicable diseases and obesity are between the major health threat due to consumption of unhealthy foods and limited time spent on physical activities, a situation of particular concern among children. Since children spend most of their time at school, this study intends to investigate the effect of a school intervention program, which combines recreational football and nutrition education, on body composition, physical fitness, physical activity, blood pressure and heart rate, eating behaviours, nutritional knowledge, and psychological status in elementary school children. Methods: A total of 67 children, between 7 and 10 years old, were allocated into three groups: the Football Group (FG) which held 2 weekly sessions of 60 min of recreational football, the Nutrition and Football Group (NFG) which held 2 sessions per week of 60 min of recreational football plus 60 min of nutritional education and the Control Group (CG) which maintained its usual curriculum. The intervention lasted 12 weeks. All measurements were collected before and after the intervention. Results: Intervention groups significantly (p < 0.05) improved BMI Z-score, rest heart rate, horizontal jump and shuttle test, physical activity level, and psychosocial health. The NFG group significantly decreased (p < 0.05) waist-to-height ratio and blood pressure, and significantly increased (p < 0.05) nutritional knowledge, fruit, and fish consumption. While FG significantly decreased (p < 0.05) the percentage of fat mass and significantly increased (p < 0.05) muscle mass and performance in the 20 m sprint. Discussion: The results have shown to improve nutritional status, explosive strength, aerobic and neuromuscular fitness, as well as increase the level of physical activity. The nutritional education sessions contributed to increase nutritional knowledge and to improve the consumption of healthy food groups in a ludic-educational way. The "Football and Nutrition for Health" program was able to induce short-term improvements in several health markers, highlighting the role of the school curriculum in children's health.

Exploring Gut Microbiota and the Influence of Physical Activity Interventions on Overweight and Obese Children and Adolescents: A Systematic Review.

The recognition that the gut microbiota of obese children differs from lean children has grown, and some studies suggest that physical activity positively influences the gut microbiota. This systematic review explores the changes in the gut microbiota composition of obese and non-obese children and adolescents and provides an understanding of the effects of physical activity interventions in modulating their microbiota. The PRISMA protocol was used across PubMed, Scopus, and Web of Science. Overall, twenty-four research papers were included in accordance with the chosen inclusion and exclusion criteria, eighteen studies compared the gut microbiota of obese and normal-weight children and adolescents, and six studies explored the effect of physical activity interventions on the gut microbiota. The analysis indicated that obese gut microbiota is reduced in Bacteroidetes, Bifidobacterium and alpha diversity but enriched in Proteobacteria and Lactobacillus. Interventions with physical activity seem to improve the alpha diversity and beneficial bacteria linked to body weight loss in children and adolescents. The gut microbiota of obese children exhibited a remarkably individual variation. More interventions are needed to clearly and accurately explore the relationships between child obesity, gut microbiota, and physical activity and to develop approaches to decrease the incidence of paediatric obesity.

Effects of Physical Activity and Nutrition Education on the Gut Microbiota in Overweight and Obese Children.

Childhood obesity continues to represent a growing challenge, and it has been associated with gut microbiota dysbiosis. This study examines the gut microbiota composition in overweight and obese school children and assesses whether a 12-week multidisciplinary intervention can induce changes in the gut microbiota. The intervention, which combined recreational football and nutritional education, was implemented among 15 school children, aged 7-10 years, with a Body Mass Index ≥ 85th percentile. The children were assigned into two groups: Football Group (n = 9) and Nutrition and Football Group (n = 6). Faecal samples were collected at the beginning and end of the program and analysed by sequencing the 16S rRNA gene. Over the intervention, a significant decrease was found collectively for Bifidobacterium genera (p = 0.011) and for Roseburia genera in the Football Group (p = 0.021). The relative abundance of Roseburia (p = 0.002) and Roseburia faecis (p = 0.009) was negatively correlated with moderate to vigorous physical activity (MVPA), while Prevotella copri was positively correlated with MVPA (p = 0.010) and with the daily intake of protein (p = 0.008). Our findings suggest that a multidisciplinary intervention was capable of inducing limited but significant positive changes in the gut microbiota composition in overweight and obese school children.

Reliability of Maximal Strength and Peak Rate of Force Development in a Portable Nordic Hamstrings Exercise Device.

The Nordic hamstring exercise (NHE) is a very popular exercise used to improve eccentric strength and prevent injuries. The aim of this investigation was to assess the reliability of a portable dynamometer that measures maximal strength (MS) and rate of force development (RFD) during the NHE. Seventeen physically active participants (34.8 ± 4.1 years; n = 2 women and n = 15 men) participated. Measurements occurred on two different days separated by 48-72 h. Test-retest reliability was calculated for bilateral MS and RFD. No significant test-retest differences were observed in NHE (test-retest [95% CI, confidence interval]) for MS [-19.2 N (-67.8; 29.4); p = 0.42] and RFD [-70.4 N·s-1 (-178.4; 37.8); p = 0.19]. MS showed high reliability (intraclass correlation coefficient [ICC] [95% CI], =0.93 [0.80-0.97] and large within-subject correlation between test and retest [r = 0.88 (0.68; 0.95)]. RFD displayed good reliability [ICC = 0.76 (0.35; 0.91)] and moderate within-subject correlation between test and retest [r = 0.63 (0.22; 0.85)]. Bilateral MS and RFD displayed a coefficient of variation of 3.4% and 4.6%, respectively, between tests. The standard error of measurement and the minimal detectable change for MS was 44.6 arbitrary units (a.u.) and 123.6 a.u., and 104.6 a.u. and 290.0 a.u. for peak RFD. This study shows that MS and RFD can be measured for NHE using a portable dynamometer. However, not all exercises are suitable to apply to determine RFD, so caution must be taken when analyzing RFD during NHE.

Effects of dietary supplements on athletic performance in elite soccer players: a systematic review.

Dietary supplements are widely used among athletes, and soccer players are no exception. Nevertheless, evidence supporting the use of dietary supplements aiming to enhance performance in soccer is somewhat contradictory, scarce, or even nonexistent. Thus, the present study aimed to systematically review and synthesize the effects of dietary supplements on athletic performance (e.g. distance covered, sprinting, jump performance) in elite soccer players. Studies enrolling highly trained, elite, and world-class soccer players using dietary supplements were searched in MEDLINE/PubMed, Web of Science, Scopus, and EBSCO databases in June 2022. In total, 1043 studies were identified, and 18 met the eligibility criteria. The studies evaluated the impacts on athletic performance of several dietary supplements, including caffeine, creatine, protein, beverages with carbohydrates and electrolytes, tart cherry juice, nitrate-rich beetroot juice, sodium bicarbonate with minerals, yohimbine, and a proprietary nutraceutical blend. Caffeine supplementation in doses between 3 and 6 mg/kg of body mass may improve jump height and sprint ability, particularly in female players, but individual response to caffeine must be considered. Creatine may improve sprint, agility, and in female players, jump performance. Protein supplementation can improve sprint and jump performance between matches, especially if protein ingested from food is not up to recommendations. Beverages containing carbohydrates and electrolytes can be used as part of the strategies to achieve carbohydrate intake during training and match-days but used alone do not benefit athletic performance. Tart cherry juice might be useful for maintaining athletic performance after matches that produce higher force loss and exercise-induced muscle damage, although polyphenols from the diet might attenuate the effects of tart cherry supplementation. Nitrate-rich beetroot concentrate can attenuate performance decrease in the days following matches. Further investigation with sodium bicarbonate alone is necessary, as supplementation protocols with elite players included other substances. Finally, the available data does not support yohimbine supplementation or the use of Resurgex Plus® to improve athletic performance in elite soccer players. Still, more well-designed research with elite soccer players is needed to improve support and advice regarding the use of dietary supplements for athletic performance enhancement.

The Impact of Sleep Interventions on Athletic Performance: A Systematic Review.

BACKGROUND: Sleep is essential for maximal performance in the athletic population. Despite that, the sport context has many factors that can negatively influence athletes' sleep and subsequent recovery. OBJECTIVES: The purpose of this systematic review was to synthesize the most recent literature regarding sleep interventions aimed at improving sleep and subsequent performance in athletes. METHODS: The present systematic review was conducted based on the PRISMA guidelines and the PICOS approach. The search was conducted in May 2022 using the electronic database PubMed, SPORTDiscus via EBSCOhost, and Web of Science. Once extracted, studies were included if they met the following criteria: (1) participants were athletes of individual or team sports; (2) implemented an intervention aimed at improving sleep; (3) measured at least one objective performance/recovery outcome; and (4) reported the relationship between sleep and performance. RESULTS: The search returned 1584 records. Following the screening, a total of 25 studies met our inclusion criteria. All the included articles were intervention studies published between 2011 and 2021. The included studies implemented various sleep interventions, such as sleep hygiene, naps, sleep extension, light manipulation, cold water immersion, mindfulness, or a combination of two or more strategies. Sleep extension and naps were the most representative and most effective strategies to improve sleep and performance. Mindfulness and light manipulation demonstrated promising results, but more studies are needed to confirm these findings. Sleep hygiene, removing electronic devices at night, and cold water immersion had no effects on sleep and subsequent performance/recovery, but these results are based on a few studies only. CONCLUSION: While acknowledging the limited amount of high-quality evidence reviewed, it appears that increasing sleep duration at night or through napping was the most effective interventions to improve physical and/or cognitive performance. Protocol Registration This protocol was registered in the International Platform of Registered Systematic Review and Meta-Analysis Protocols (INPLASY) on May 11, 2022, with the registration number INPLASY202250069.

Intraindividual Relationships Between Training Loads and Heart-Rate Variability in High-Level Female Futsal Players: A Longitudinal Study.

PURPOSE: To investigate the internal training loads of a professional Spanish female futsal team throughout 26 weeks of training including preseason and in-season weeks and verify the impact of training period and/or training load magnitudes on heart-rate variability responses. Furthermore, we aimed to assess, intraindividually, the relationship between training load and the coefficient of variation (CV) of weekly natural log of the root mean square difference of successive normal interbeat (RR) intervals (lnRMSSDCV), obtained from ∼5 measures per week, and recorded in the seated position. METHODS: A within-subject design involved 12 high-level outfield female futsal players (mean [SD] age: 23.9 [3.4] y). RESULTS: lnRMSSD was significantly lower and lnRMSSDCV was significantly higher during the preseason (weeks 1-6) compared to in-season (weeks 7-26) (P < .001). Individually, players presented moderate to large negative correlations between lnRMSSDCV and lnRMSSD during the 26 weeks of observation. Correlations ranged between rplayer4 = -.41 (95% CI, -.69 to -.02) and rplayer12 = -.55 (-.78 to -.18). Players also presented moderate to very large positive correlations between lnRMSSDCV and session rating of perceived exertion. Correlations ranged between rplayer7 = .41 (.04 to .71) and rplayer1 = .71 (.45 to .86). CONCLUSION: Professional female futsal players in this study presented increased lnRMSSD and reduced lnRMSSDCV during 20 weeks into the competitive season compared to 6 weeks of preseason. Furthermore, lnRMSSDCV was negatively associated with lnRMSSD on an intraindividual basis. Finally, higher internal training loads were positively correlated with lnRMSSDCV, indicating that heart-rate variability is responsive to weekly training loads.

Comparing Sleep in Shared and Individual Rooms During Training Camps in Elite Youth Soccer Players: A Short Report.

CONTEXT: Athletes' sleep is the most important recovery strategy and has received growing attention. However, athletes may experience sleep disruptions due to numerous factors, such as training and competition workloads, travel, changes in sleep-wake schedules, and sleeping environments. They often spend nights in unfamiliar hotels, and sharing a bed, room, or both with another person might affect sleep duration and quality. OBJECTIVE: To analyze the effect of sleeping in shared (SRs) versus individual (IRs) rooms on objective and subjective sleep and on slow-wave-sleep-derived cardiac autonomic activity during an official training camp in elite youth soccer players. Training and match workloads were characterized. DESIGN: Observational case study. SETTING: Hotel accommodations. PATIENTS OR OTHER PARTICIPANTS: Thirteen elite male youth soccer players. RESULTS: Players slept longer in IRs than in SRs (+1:28 [95% CI = 1:18, 1:42] hours:minutes; P < .001). Sleep efficiency was higher in IRs than in SRs (+12% [95% CI = 10%, 15%]; P < .001), whereas sleep latency was shorter in IRs than in SRs (-3 [95% CI = -15, -4] minutes; P < .001). Subjective sleep quality was lower in IRs than in SRs (-2 [-3 to -2] arbitrary units; P < .001). No differences were found for slow-wave-sleep-derived cardiac autonomic activity or for training or match workloads between training camps. CONCLUSIONS: During soccer training camps, sleep may be affected by whether the athlete is in an SR versus an IR.

Training in women soccer players: A systematic review on training load monitoring.

Objective: The present systematic review aimed to provide an overview of training load (TL), along with their responses, monitoring during training sessions in highly trained and elite adult women soccer players. Data source: Electronic databases searches (PubMed, Scopus, Web of Science and Ebsco) for relevant studies published in peer-reviewed journals were conducted, and eligibility criteria were based on the PICOS model in accordance with PRISMA guidelines. Study selection: Studies were considered as follows: (a) highly trained and elite adult (>18 years) women's soccer players; (b) continuous (minimum 1-week duration) TL monitoring in the context of the team routine; (c) TL collected from entire training session. Methodological qualitative assessments and risk of bias criteria were used for judging the studies. Data extraction: A total of 1,163 studies were identified, and 16 were included. The selected studies were fully screened to extract the population characteristics; the number of players; a type of study design; region where the study was performed; the main findings. Data synthesis: Accumulated external TL (ETL) during the pre-season was positively correlated to enhanced adaptations in intermittent exercise capacity. Daily ETL was negatively correlated to next-day self-reported fatigue and muscle soreness. Daily internal TL (ITL) was negatively correlated to post-session sleep duration and sleep efficiency. One study showed that higher accumulated player load and total distance were associated with injury. Conclusion: Information about TL during training sessions in women soccer players is very sparse, and it is currently very difficult to consider evidence-based practices for training sessions in highly trained and elite adult women soccer players. Moreover, the dose-response relationships between TL and training outcome (e.g., fatigue, training adaptations and injuries) need to be further explored to understand the optimal training stimulus to enhance performance outcomes while preserving player health.

Associations between Training Load and Well-Being in Elite Beach Soccer Players: A Case Report.

The current case study aimed to quantify within-subjects correlations between training load and well-being in elite male beach soccer players. Data were obtained over three consecutive days during the preparation camp for the FIFA Beach Soccer World Cup Russia 2021. The session rating of perceived exertion (s-RPE) and external training load metrics using global positioning system (GPS) were recorded. Eleven players reported perceived well-being (sleep quality, fatigue, muscle soreness and stress) using a Likert scale (Hooper Index) before breakfast. Within-subjects correlation coefficients between workload and well-being were calculated. Workload metrics and perceived well-being indices were significantly lower on day three than on days one and two. The Hooper Index presented a very large positive correlation with s-RPE (r = 0.86 [0.67, 0.94], 95% confidence interval, CI), exposure time (r = 0.88 [0.71, 0.95]), total distance (r = 0.83 [0.60, 0.93]), high-speed distance (r = 0.77 [0.50, 0.91]), and number of sprints (r = 0.75 [0.47, 0.90]). Sleep quality presented a moderate to large positive correlation with s-RPE (r = 0.51 [0.11, 0.77]), exposure time (r = 0.50 [0.10, 0.76]), high-speed distance (r = 0.53 [0.15, 0.78]), number of sprints (r = 0.62 [0.28, 0.83]) and total distance (r = 0.41 [0.18, 0.78]). Fatigue presented a large to very large positive correlation with s-RPE (r = 0.85 [0.66, 0.94]), exposure time (r = 0.90 [0.78, 0.96]), total distance (r = 0.86 [0.68, 0.94]), high-speed distance (r = 0.65 [0.31, 0.84]) and number of sprints (r = 0.56 [0.18, 0.79]). Muscle soreness presented a large to very large positive correlation with s-RPE (r = 0.79 [0.56, 0.91]), exposure time (r = 0.83 [0.62, 0.93]), total distance (r = 0.81 [0.59, 0.92]), high-speed distance (r = 0.75 [0.47, 0.89]) and number of sprints (r = 0.59 [0.22, 0.81]). Overall, workload presented a meaningful correlation with perceived well-being indices in elite male beach soccer players during a training camp. These findings suggest that workload metrics and perceived well-being indices can be implemented into the daily routine of an elite beach soccer team, which may assist coaches, sports scientists, and practitioners in better preparing players for beach soccer competitions.

Associations Between Esports Participation and Health: A Scoping Review.

Esports are a contemporary phenomenon, with millions of people involved. Still, scientific literature on the topic is scarce. Anecdotal reports, mostly based on what is known from videogames practice, have associated esports with unhealthy lifestyles and health-related problems. The present scoping review aimed to provide an overview of findings from studies regarding the health and well-being in adult esports players, while identifying the most studied topics in the field and those still lacking scientific research.The search was conducted in MEDLINE, Scopus, Web of Science, B-on, and ESCBO databases. Studies regarding health consequences of esports practice conducted with adult esports players were included. No exclusion criteria concerning age, sex, esports modality, or esports level were applied, but articles related to other forms of video gaming or gambling were excluded. The search was limited to peer-reviewed articles. Opinion and review articles were excluded.There were 1416 articles retrieved from which 33 met the inclusion criteria. Lifestyle habits, sleep, exercise and physical health (including musculoskeletal health), physiological demands, and mental health were the main topics of investigation. Several gaps in the literature were identified, namely studies on cardiovascular, respiratory, or metabolic health, or consuming-related risks. Also, the lack of homogeneous methodologies and definitions used in esports-related studies was identified.Esports practice has been associated with different health-related symptoms, but more studies using more robust methodologies and appropriate research design are needed. Topics such as cardiovascular health or the use of performance-enhancing drugs are lacking.

Anecdotal reports have associated esports with unhealthy lifestyles and health-related problems. Still, scientific literature about esports is scarce. The current scoping review aimed to better understand health and well-being in esports players, while identifying the topics most studied in the field and those which might still be lacking scientific knowledge.Lifestyle habits, sleep characteristics, exercise and physical health, including musculoskeletal health, physiological demands, and mental health were the main topics approached within the 33 articles included in the present scoping review. Several gaps in the literature were identified, namely studies on cardiovascular, respiratory, or metabolic health, or consuming-related risks. Also, the lack of homogeneous methodologies and definitions used in the esports scene was identified.Esports practice has been associated with different health-related symptoms, but studies on esports using robust methodologies and appropriate research design are needed. Studies on topics such as cardiovascular health or the use of performance-enhancing drugs are lacking.

Using the Rating of Perceived Exertion and Heart Rate to Quantify Training Intensity in Female Soccer Players: Validity and Utility.

ABSTRACT: Costa, JA, Brito, J, Nakamura, FY, Figueiredo, P, and Rebelo, A. Using the rating of perceived exertion and heart rate to quantify training intensity in female soccer players: validity and utility. J Strength Cond Res 36(1): 201-206, 2022-The aims of this study were as follows: (a) to analyze associations between session rating of perceived exertion (sRPE) and training impulse (TRIMP); (b) to verify whether significantly different ranges of percentage of heart rate peak (%HRpeak) would be reached in each discrete RPE category; and (c) to investigate the amount of time spent >90% of HRpeak and associated intraplayer and interplayer variability during soccer technical training sessions with similar contents and duration. This was a single-group observational study that measured the internal training load during 6 weeks of the competitive period in 17 high-level female soccer players. All training sessions started around 9 pm. and lasted on average 94 ± 5 minutes. During each training session, RPE, sRPE, TRIMP, HRex (%HRpeak), and time spent at >90% of HRpeak were assessed. A very large correlation was found between sRPE and TRIMP (r = 0.78; 95% confidence interval: [0.74-0.82]). Significant differences were observed between %HRpeak associated with each RPE value (i.e., RPE = 2 arbitrary unit [68%; 65-69% of %HRpeak]; RPE 3 [72%; 69-75%]; RPE 4 [79%; 76-82%]; RPE 5 [84; 81-87%]; χ2 = 73.34; df = 3; P < 0.001). Intraplayer and interplayer coefficients of variation for the time spent >90% of HRpeak (∼8% of training time, ∼7 minutes per session) during training sessions were 73 and 92%, respectively. In conclusion, it was confirmed that sRPE and TRIMP displayed good convergent validity, and different %HRpeak were observed for each discrete RPE. However, because of the high variability in the time >90% of HRpeak, careful monitoring of individual exercises should be performed to ensure the desired training stimulus for each player.

Associations between 24-h heart rate variability and aerobic fitness in high-level female soccer players.

OBJECTIVE: The aim of this study was to investigate the changes in 24-h heart rate variability and aerobic fitness, and their associations, in female soccer players during the preseason period. METHODS: Sixteen players were assessed (24-h HRV and Yo-Yo Intermittent Recovery Test, level 1 [YYIR1]) before and after 4 weeks of preseason. The relationship between R-R24h length and high-frequency oscillations (HF24h) was analyzed by a quadratic regression model (revealing or not saturation of vagal activity) assessed 48-h before (PRE-preseason) and 48-h after (POST-preseason) the preseason period. Additionally, the mean HF24h was calculated from the linear portion of the R-R interval versus the HF24h regression curve (HF index). The average of the corresponding R-R24h values was defined as the R-R index. RESULTS: In PRE-preseason, seven players had a saturated HF24h, while in POST-preseason, five new cases of saturated HF24h were observed. The mean R-R24h, HF24h, R-R index, and HF index lengths significantly increased after preseason (p < 0.001). Significant differences were found in YYIR1 PRE- compared with POST-preseason (930 ± 286 m [individual range: 400-1240 m] versus 1265 ± 252 m [640-1640 m], respectively; p < 0.001). Additionally, the relative changes in HF24h and HF index were largely correlated with improvements in the distance covered during the YYIR1 (r = 0.68 and r = 0.56; respectively). CONCLUSION: Enhanced vagal activity after 4-week preseason period of soccer training increased the occurrence of vagal saturation in high-level female soccer players. Additionally, the increases in HF24h and HF index were significantly correlated with aerobic fitness change.

Monitoring Individual Sleep and Nocturnal Heart Rate Variability Indices: The Impact of Training and Match Schedule and Load in High-Level Female Soccer Players.

PURPOSE: To describe individual sleep habits and nocturnal heart rate variability (HRV) responses, and to explore intra-individual associations of workload with sleep and nocturnal HRV indices in high-level female soccer players throughout a 2-week competitive period. MATERIALS AND METHODS: The study followed a descriptive, observational design. Thirty-four high-level female soccer players (aged 20.6 ± 2.3 years) wore wrist actigraph units and heart rate (HR) monitors during night-sleep to record objective sleep and HRV data throughout 14 days [six evening-time training sessions (ET), six rest-days (RD), and two match-days (MD)]. During each ET and MD, exercise HR (HRexe), %HRpeak, training impulse (TRIMP), session rating of perceived exertion (s-RPE) and perceived ratings of wellbeing were monitored. RESULTS: After ET, a higher number of players (17-22) slept less than 7 h/night, in contrast to the remaining days (i.e., MD and RD), but only 1-6 players had a sleep efficiency < 75%. The coefficient of variation (CV) for sleep duration and sleep efficiency ranged between 9-22% and 2-11%, respectively. A small negative within-subject correlation was found between TRIMP and sleep duration [r = -0.25 (-0.36; -0.12); P < 0.001] and sleep efficiency [r = -0.20 (-0.32; -0.08); P = 0.004]. A moderate and small negative within-subject correlation was found between s-RPE and sleep duration [r = -0.43 (-0.53; -0.32); P < 0.001] and sleep efficiency [r = -0.17 (-0.30; -0.05); P = 0.02]. Nocturnal HRV for the time-domain analyses ranged from 4.1 (3.9; 4.3) to 4.4 (4.1; 4.6) ln[ms], and for the frequency-domain analyses ranged from 6.3 (5.9; 6.7) to 7.5 (7.1; 7.9) ln[ms2]. CV for time-domain HRV ranged from 3 to 23%, and from 4 to 46% for the frequency-domain. Higher CV fluctuations in time- and frequency-domain HRV were particularly observed in four players. CONCLUSION: Overall, this study highlights the individual variability of sleep and nocturnal HRV indices, indicating that sleep duration may be affected by training and match schedules and workloads. Training and matches workload were not associated with nocturnal HRV in high-level female soccer players.

Heart Rate Variability Changes From Traditional vs. Ultra-Short-Term Recordings in Relation to Preseason Training Load and Performance in Futsal Players.

Nakamura, FY, Antunes, P, Nunes, C, Costa, JA, Esco, MR, and Travassos, B. Heart rate variability changes from traditional vs. ultra-short-term recordings in relation to preseason training load and performance in futsal players. J Strength Cond Res 34(10): 2974-2981, 2020-The aims of this study were to analyze heart rate variability (HRV) changes in futsal players during preseason training using both "criterion" (10-minute) and ultra-shortened (2-minute) measures, and to determine whether they were related to changes in the Yo-Yo Intermittent Recovery Test, level 1 (Yo-Yo IR1) performance and accumulated training load (TL). Eleven male competitive futsal players (age = 25.19 ± 4.70 years; body mass = 73.15 ± 11.70 kg; and height = 176.90 ± 5.01 cm) volunteered for the study. Data collection took place during the first to the fourth weeks of preseason training. Training load was monitored with session ratings of perceived exertion. The total distance (TD) covered during the Yo-Yo IR1 was recorded during week 1 and week 4. Heart rate variability was measured through the log-transformed root mean square of successive normal-to-normal interval differences using the ultra-short analysis, with its weekly mean (lnRMSSDM) and coefficient of variation (lnRMSSDCV) recorded, and by means of the criterion method (weeks 1 and 4). lnRMSSDM was likely higher at week 4 compared with week 1 using both criterion and ultra-short recordings. Moderate-to-large correlations were found between changes in the lnRMSSDM and lnRMSSDCV values and changes in TL and TD (r values ranged from -0.48 to 0.65). Changes in ultra-short HRV measures (i.e., increase in lnRMSSDM and decrease in lnRMSSDCV) during futsal preseason were associated with increased performance. The players who accumulated higher perceived TLs displayed smaller improvements in the Yo-Yo IR1 performance and HRV.