Caffeine supplementation during official basketball games: a randomized crossover study on the effects on game-related statistics and perceptual responses of adult male players.

BACKGROUND: This study examined the effects of caffeine (CAF) supplementation on game-related statistics and perceptual responses of male basketball players during official games. METHODS: Eight players (23.5±5.7 years) participated in this double-blind, placebo-controlled, randomized crossover study. Sixty minutes before the start of each game, players ingested a dose of either CAF (3 mg/kg body mass) or placebo (PLA) in a randomized order. Game-related statistics were collected. After the games, players reported ratings of perceived exertion (RPE) and their perceptions of endurance and power. Separate linear mixed models evaluated the effects of treatment (CAF, PLA), game location (home, away), and opponent level (better, worse) on game-related statistics and perceptual responses. RESULTS: Players committed fewer fouls when taking CAF compared to PLA (P<0.001, ES=0.75, moderate). No effects of CAF were found for the other game-related statistics (all P>0.05). RPE was higher in CAF compared to PLA (P=0.031, ES: 0.49, small). There were no differences in perceptions of endurance (P=0.388) or power (P=0.988). No effects of game location or opponent level were found for game-related statistics or perceptual responses (all P>0.05). CONCLUSIONS: This study suggests that caffeine supplementation can improve defensive performance in semiprofessional basketball players while also possibly increasing physical performances, seen the higher RPE.

Effect of COVID-19 on Injury Incidence and Severity in Professional Female Football Players: A Cohort Prospective Study.

BACKGROUND: Earlier statements suggested a negative impact of coronavirus disease 2019 (COVID-19) infection on sports performance and injury risk. With the COVID-19 pandemic under control and the dominance of a less-severe strain of the virus, there is a need to confirm whether these adverse effects still apply to the current situation. HYPOTHESIS: Infected players would have a higher noncontact muscle injury incidence compared with noninfected counterparts. STUDY DESIGN: Cohort observational study. LEVEL OF EVIDENCE: Level 3. METHODS: Seven teams (n = 147 players) competing in the Spanish professional women's football league (Liga F) were prospectively monitored during the 2021-2022 season. Data from noncontact injuries were recorded and classified following the latest consensus statement from the International Olympic Committee. COVID-19 was certified by the medical staff by regular polymerase chain reaction analysis. RESULTS: Ninety-two players suffered at least 1 noncontact muscle injury during the season. Injury incidence during the season was similar in players with COVID-19 (n = 83) and players without infection (5.1 ± 6.7 versus 4.9 ± 10.0 injuries/1000 h of play, respectively; P = 0.90). Players with COVID-19 were not more likely to suffer noncontact injuries compared with those players without infection (R2 = 0.02; odds ratio [OR] 95% confidence interval [95% CI] = 0.36-1.38; P = 0.31). There was no effect of COVID-19 on the days of absence due to injury (R2 = 0.01; OR 95% CI = 1.00-1.01; P = 0.44) or in the classification of the severity of the injury (P = 0.79). CONCLUSION: COVID-19 has no significant effect on noncontact injury incidence and severity in professional female football players. CLINICAL RELEVANCE: Currently, COVID-19 infection does not alter noncontact muscle injury risk in professional football and requires no further attention in terms of injury management. Usual return-to-play protocols apply to COVID-19 considering the particularities of each player since the severity of infection, period of inactivity, and effects on the player's health and performance.

Can Caffeine Change the Game? Effects of Acute Caffeine Intake on Specific Performance in Intermittent Sports During Competition: A Systematic Review and Meta-Analysis.

BACKGROUND: The benefits of oral caffeine intake to enhance several aspects of physical performance, such as aerobic endurance, strength, power, and muscle endurance performance, are well supported. However, how the physical performance benefits of caffeine supplementation are translated into better specific actions in intermittent sports during real or simulated competition has been the topic of fewer investigations, and their results need to be appropriately reviewed and meta-analyzed. OBJECTIVE: The aim of the study was to investigate the effects of acute caffeine intake on specific actions in intermittent sports involving decision making and high-intensity efforts (eg, team, racket, and combat sports) during real or simulated competitions. METHODS: All studies included had blinded and crossover experimental designs, and we conducted a risk-of-bias analysis. In total, we included 24 studies. A meta-analysis was performed using the random-effects model to calculate the standardized mean difference (SMD) estimated by Hedges g and 95% CIs. RESULTS: Caffeine ingestion increased high-intensity sport-specific actions during competition, such as the number of sprints (SMD: 0.48; 95% CI, 0.23-0.74), body impacts (SMD: 0.28; 95% CI, 0.08-0.49), accelerations (SMD: 0.35; 95% CI, 0.06-0.63), decelerations (SMD: 0.63; 95% CI, 0.12-1.14), and high-intensity offensive efforts (SMD: 0.36; 95% CI, 0.11-0.61). Additionally, caffeine ingestion induced a higher positive or success rate of actions during real or simulated competition (SMD: 0.44; 95% CI, 0.19-0.69). CONCLUSION: The current meta-analysis provides evidence of caffeine supplementation in increasing high-intensity efforts and the success rate of sport-specific actions during real or simulated competition.

Body Composition and Dietary Intake Profiles of Elite Iranian Swimmers and Water Polo Athletes.

BACKGROUND: This study aimed to conduct a detailed and comparative analysis of body composition and dietary habits in elite swimming and water polo athletes. Through the examination of these key parameters, this study seeks to compare the dietary intake of these two distinct aquatic sports disciplines. METHODS: A total of 10 top-level swimmers and 13 water polo athletes participated in anthropometric and body composition assessments, as well as a detailed analysis of nutritional intake. To compare the two groups, an independent samples t-test was used, and variance homogeneity was checked using Levene's test. The effect size of the group differences was evaluated using Hedges' g. RESULTS: Water polo athletes showed significantly greater height (189.4 ± 2.9 vs. 186.5 ± 2.0 cm, p = 0.013), body mass index (24.3 ± 1.4 vs. 22.1 ± 0.5 kg/m2, p < 0.001), fat-free mass (62.9 ± 1.4 vs. 61.1 ± 1.38 kg, p < 0.001), skeletal muscle mass (47.1 ± 1.3 vs. 43.9 ± 1.6 kg, p < 0.001), and overall weight (86.9 ± 6.9 vs. 76.7 ± 2.2 kg, p < 0.001) in comparison to swimmers. Swimmers consumed greater amounts of mean daily energy (60.0 ± 1.0 vs. 39.0 ± 1.0 kcal/kg, p < 0.001), carbohydrate (7.8 ± 0.3 vs. 4.4 ± 0.5 g/kg, p < 0.001), protein (1.7 ± 0.5 vs. 1.4 ± 0.5 g/kg, p < 0.001), and fat (2.4 ± 0.5 vs. 1.7 ± 0.5 g/kg, p < 0.001) compared to water polo athletes. CONCLUSION: Our findings highlight the need for differentiated targeted nutritional interventions to enhance athletic performance in different types of water sports. Compared to water polo athletes, swimmers consumed significantly higher amounts of calories, matching their increased calorie demand from their specific training regime. However, this is an observational study and the differential needs of energy and macronutrients in water sports should be confirmed by studies with energy expenditure measurements.

Deceleration Capacity During Directional Change as a Time-Efficient (Ecological) Prescreening of Hip Adductor Force Status in Amateur Soccer Players.

ABSTRACT: Miralles-Iborra, A, Del Coso, J, De Los Ríos-Calonge, J, Elvira, JLL, Barbado, D, Urban, T, and Moreno-Pérez, V. Deceleration capacity during directional change as a time-efficient (ecological) prescreening of hip adductor force status in amateur soccer players. J Strength Cond Res XX(X): 000-000, 2024-Reduced isometric adductor muscle strength has been identified as a modifiable risk factor contributing to injury in soccer players. However, the measurement of hip adductor muscle strength is habitually laboratory-based, with isolated hip movements that do not reflect soccer-specific movements that induce groin injury during match play. This study aimed to determine the usefulness of deceleration capacity during a change of direction (COD) as a time-efficient (ecological) prescreening of hip adductor force status in soccer players. Nineteen amateur soccer players completed unilateral isometric hip adductor strength assessments and a 180° COD test. Isometric hip strength assessment included the maximum peak torque (PT) and maximum rate of torque development (RTDmax) relative to players' body mass. Players' deceleration capacity during the COD test was determined for each leg through maximum deceleration normalized to the linear momentum. A linear regression analysis was performed to associate isometric hip strength variables with the deceleration capacity during the COD test at each leg. There was not a statistically significant association between deceleration capacity and hip isometric maximum PT of the dominant and nondominant legs (r ≤ 0.14, p > 0.05). Nevertheless, a moderate association was found between deceleration capacity and RTDmax for both legs (r ≥ 0.58, p < 0.05). The optimal linear regression model suggests that measuring deceleration capacity during a directional change test could explain RTDmax by 33 and 43% for the dominant and nondominant legs, respectively. During a 180° COD test, the deceleration capacity captured through GPS-accelerometer device was limited as a prescreening tool to evaluate hip adductor force status in soccer players.

Influence of the External Workload on Calf Muscle Strain Injuries in Professional Football Players: A Pilot Study.

BACKGROUND: The influence of external workload variables on the development of calf muscle strainsin football players has not been previously explored. HYPOTHESIS: Overloaded players would have an increased risk of calf muscle strain injury. STUDY DESIGN: Prospective observational study. LEVEL OF EVIDENCE: Level 4. METHODS: A total of 41 professional football players from 1 team were monitored for 2 consecutive seasons. Total distance covered (TD), and distances covered at high-intensity running, high sprint running, low (LACC) and high (HACC) acceleration, low (LDEC) and high (HDEC) deceleration, and at high metabolic load distance (HMLD) were monitored with GPS units. Accumulated players' external workload in the week before injury was compared with the weekly mean value of the 6 weeks before injury occurred for each player. RESULTS: Ten players (24.3%) suffered 16 calf muscle strain injuries (3.1 injuries per 1000 hours of match play; 0.5 injuries per 1000 hours of training exposure). Players with a calf muscle injury were older (p = 0.03), with higher body weight (p = 0.01) and height (p = 0.03). Injured players displayed substantially higher total training volume (p < 0.01), TD (p < 0.01), LACC (p < 0.01), LDEC (p < 0.01), HACC (p < 0.01), HDEC (p < 0.01), and HMLD (p = 0.03) in the week before injury, in comparison with the mean values of these variables in the 6 weeks before injury. CONCLUSION: A week with a higher-than-habitual external workload might increase the risk of calf muscle strain injury in professional football players. Calf muscle injuries were preceded by a week with unusually high workloads associated with accelerating and decelerating distances and higher training volumes. CLINICAL RELEVANCE: Monitoring external workload indicators may be helpful in determine players with a higher risk of calf muscle strain injury due to excessive workload during training/competition.

Genotypic and Allelic Distribution of the CD36 rs1761667 Polymorphism in High-Level Moroccan Athletes: A Pilot Study.

Previous studies have shown that variations in the CD36 gene may affect phenotypes associated with fat metabolism as the CD36 protein facilitates the transport of fatty acids to the mitochondria for oxidation. However, no previous study has tested whether variations in the CD36 gene are associated with sports performance. We investigated the genotypic and allelic distribution of the single-nucleotide polymorphism (SNP) rs1761667 in the CD36 gene in elite Moroccan athletes (cyclists and hockey players) in comparison with healthy non-athletes of the same ethnic origin. Forty-three Moroccan elite male athletes (nineteen cyclists and twenty-four field hockey players) belonging to the national teams of their respective sports (athlete group) were compared to twenty-eight healthy, active, male university students (control group). Genotyping of the CD36 rs1761667 (G>A) SNP was performed via polymerase chain reaction (PCR) and Sanger sequencing. A chi-square (χ2) test was used to assess the Hardy-Weinberg equilibrium (HWE) and to compare allele and genotype frequencies in the "athlete" and "control" groups. The genotypic distribution of the CD36 rs1761667 polymorphism was similar in elite athletes (AA: 23.81, AG: 59.52, and GG: 16.67%) and controls (AA: 19.23, AG: 69.23, and GG: 11.54%; χ2 = 0.67, p = 0.71). However, the genotypic distribution of the CD36 rs1761667 polymorphism was different between cyclists (AA: 0.00, AG: 72.22, and GG: 27.78%) and hockey players (AA: 41.67, AG: 50.00, and GG: 8.33%; χ2 = 10.69, p = 0.004). Specifically, the frequency of the AA genotype was significantly lower in cyclists than in hockey players (p = 0.02). In terms of allele frequency, a significant difference was found between cyclists versus field hockey players (χ2 = 7.72, p = 0.005). Additionally, there was a predominance of the recessive model in cyclists over field hockey players (OR: 0.00, 95% CI: 0.00-0.35, p = 0.002). Our study shows a significant difference between cyclists and field hockey players in terms of the genotypic and allelic frequency of the SNP rs1761667 of the CD36 gene. This divergence suggests a probable association between genetic variations in the CD36 gene and the type of sport in elite Moroccan athletes.

A Systematic Review and Meta-analysis of the Association Between ACTN3 R577X Genotypes and Performance in Endurance Versus Power Athletes and Non-athletes.

BACKGROUND: Previous studies reported differences in genotype frequency of the ACTN3 R577X polymorphisms (rs1815739; RR, RX and XX) in athletes and non-athletic populations. This systematic review with meta-analysis assessed ACTN3 R577X genotype frequencies in power versus endurance athletes and non-athletes. METHODS: Five electronic databases (PubMed, Web of Science, Scopus, Science Direct, SPORTDiscus) were searched for research articles published until December 31st, 2022. Studies were included if they reported the frequency of the ACTN3 R577X genotypes in power athletes (e.g., weightlifters) and if they included a comparison with endurance athletes (e.g., long-distance runners) or non-athletic controls. A meta-analysis was then performed using either fixed or random-effects models. Pooled odds ratios (OR) were determined. Heterogeneity was detected using I2 and Cochran's Q tests. Publication bias and sensitivity analysis tests were computed. RESULTS: After screening 476 initial registrations, 25 studies were included in the final analysis (13 different countries; 14,541 participants). In power athletes, the RX genotype was predominant over the two other genotypes: RR versus RX (OR 0.70; 95% CI 0.57-0.85, p = 0.0005), RR versus XX (OR 4.26; 95% CI 3.19-5.69, p < 0.00001), RX versus XX (OR 6.58; 95% CI 5.66-7.67, p < 0.00001). The R allele was higher than the X allele (OR 2.87; 95% CI 2.35-3.50, p < 0.00001) in power athletes. Additionally, the frequency of the RR genotype was higher in power athletes than in non-athletes (OR 1.48; 95% CI 1.25-1.75, p < 0.00001). The RX genotype was similar in both groups (OR 0.84; 95% CI 0.71-1.00, p = 0.06). The XX genotype was lower in power athletes than in controls (OR 0.73; 95% CI 0.64-0.84, p < 0.00001). Furthermore, the R allele frequency was higher in power athletes than in controls (OR 1.28; 95% CI 1.19-1.38, p < 0.00001). Conversely, a higher frequency of X allele was observed in the control group compared to power athletes (OR 0.78; 95% CI 0.73-0.84, p < 0.00001). On the other hand, the frequency of the RR genotype was higher in power athletes than in endurance athletes (OR 1.27; 95% CI 1.09-1.49, p = 0.003). The frequency of the RX genotype was similar in both groups (OR 1.07; 95% CI 0.93-1.24, p = 0.36). In contrast, the frequency of the XX genotype was lower in power athletes than in endurance athletes (OR 0.63; 95% CI 0.52-0.76, p < 0.00001). In addition, the R allele was higher in power athletes than in endurance athletes (OR 1.32; 95% CI 1.11-1.57, p = 0.002). However, the X allele was higher in endurance athletes compared to power athletes (OR 0.76; 95% CI 0.64-0.90, p = 0.002). Finally, the genotypic and allelic frequency of ACTN3 genes were similar in male and female power athletes. CONCLUSIONS: The pattern of the frequencies of the ACTN3 R577X genotypes in power athletes was RX > RR > XX. However, the RR genotype and R allele were overrepresented in power athletes compared to non-athletes and endurance athletes. These data suggest that the RR genotype and R allele, which is associated with a normal expression of α-actinin-3 in fast-twitch muscle fibers, may offer some benefit in improving performance development in muscle strength and power.

Effects of exercise on life satisfaction of people diagnosed with cancer: a systematic review and meta-analysis.

PURPOSE: A cancer diagnosis is commonly associated with a decline in patient's life satisfaction and more pessimistic expectations about the future. The identification of strategies to improve life satisfaction in patients with cancer is of great interest to health practitioners since it may be associated with a better prognosis of cancer and higher survival rates. Previous meta-analyses and reviews concluded that exercise could significantly improve health-related quality of life in this population, but the effects of exercise on life satisfaction are still not well-known. This review aims to analyse the effects of exercise programs on life satisfaction in people with cancer and individuals who have overcome cancer. METHODS: The present systematic review and meta-analysis followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. A thorough search of databases including Web of Science and PubMed/MEDLINE was carried out. Six studies (535 participants) in which the effect of an exercise program was compared to a non-exercise program control condition in patients with cancer were considered eligible. A subsequent meta-analysis was performed using the random effects model to calculate the standardized mean differences (SMD) and 95% confidence intervals (CI). RESULTS: Exercise intervention improved satisfaction with life compared with a control condition (SMD = 1.28; p = 0.02 with a 95% CI of 0.22 to 2.34). CONCLUSION: Exercise could be considered an effective tool to improve life satisfaction in patients with cancer. Hence, professionals might consider the possibility of integrating physical exercise into strategies aimed at enhancing the low life satisfaction often experienced by patients. PROSPERO: CRD42023438146.

ACTN3 XX Genotype Negatively Affects Running Performance and Increases Muscle Injury Incidence in LaLiga Football Players.

The aim of this study was to investigate the association of the ACTN3 rs1815739 polymorphism with match running performance and injury incidence in top-level professional football players. A total of 315 top-level professional football players from the first division of Spanish football (i.e., LaLiga) participated in this prospective and descriptive study. The ACTN3 rs1815739 genotype was identified for each player using genomic DNA samples. During LaLiga 2021-2022, players' performance was obtained through a validated camera system in all official matches. Additionally, the incidence of non-contact injuries was obtained by each team's medical staff according to the International Olympic Committee (IOC) statement. From the study sample, 116 (36.8%) players had the RR genotype, 156 (49.5%) had the RX genotype, and 43 (13.7%) had the XX genotype. The anthropometric characteristics of the players were similar across genotypes. However, the total running distance (p = 0.046), the distance at 21.0-23.9 km/h (p = 0.042), and the number of sprints (p = 0.042) were associated with the ACTN3 genotype. In all these variables, XX players had lower match performance values than RR players. Additionally, total and match injury incidences were higher in XX players than in RR players (p = 0.026 and 0.009, respectively). The rate of muscle injuries was also higher in XX players (p = 0.016). LaLiga football players with the ACTN3 XX genotype had lower match running performance and a higher incidence of non-contact injuries over the season.

Persons With Chronic Obstructive Pulmonary Disease and High Levels of Activation Improved Their Physical Activity Skills After an Educational Session.

Background: Daily physical activity is part of the self-management of patients with chronic obstructive pulmonary disease (COPD), and didactic information sessions may be insufficient for the provision of these skills. Prior activation can determine sensitivity to these sessions. We evaluated whether the activation in patients with COPD, as measured by the Patient Activation Measure (PAM)-13 questionnaire, determined their responses to an educational group session on physical activity (PA), which were measured with actigraphy by the number of steps/day. Methods: We conducted an uncontrolled clinical trial in an outpatient clinic with 75 patients with nonexacerbating COPD (forced expiratory volume in 1 second 30%-80%) who were selected consecutively. Patients were provided with an actigraph that they used for 15 days and completed the PAM-13 questionnaire. On the eighth day, they attended a group educational session where they were given PA information. We compared the changes in activity after the session by pooled PAM levels and the correlation between the change in the number of steps/day and the PAM-13 questionnaire. Results: A total of 26 patients had activation levels of 1-2, while 49 patients had levels of 3-4. After the session, patients in Levels 1-2 decreased their number of steps (-596±42), while those in Levels 3-4 increased them (680±253, p<0.01). The level of activation was positively correlated with change in the number of steps/day (p<0.05). Conclusion: COPD patients with greater activation showed greater improvements in daily PA after a group educational session.

Effects of Caffeinated Coffee on Cross-Country Cycling Performance in Recreational Cyclists.

The ergogenic effects of acute caffeine intake on endurance cycling performance lasting ~1 h have been well documented in controlled laboratory studies. However, the potential benefits of caffeine supplementation in cycling disciplines such as cross-country/mountain biking have been rarely studied. In cross-country cycling, performance is dependent on endurance capacity, which may be enhanced by caffeine, but also on the technical ability of the cyclist to overcome the obstacles of the course. So, it is possible that the potential benefits of caffeine are not translated to cross-country cycling. The main objective of this study was to investigate the effects of acute caffeine intake, in the form of coffee, on endurance performance during a cross-country cycling time trial. Eleven recreational cross-country cyclists (mean ± SD: age: 22 ± 3 years; nine males and two females) participated in a single-blinded, randomised, counterbalanced and crossover experiment. After familiarisation with the cross-country course, participants completed two identical experimental trials after the ingestion of: (a) 3.00 mg/kg of caffeine in the form of soluble coffee or (b) 0.04 mg/kg of caffeine in the form of decaffeinated soluble coffee as a placebo. Drinks were ingested 60 min before performing a 13.90 km cross-country time trial over a course with eight sectors of varying technical difficulty. The time to complete the trial and the mean and the maximum speed were measured through Global Positioning System (GPS) technology. Heart rate was obtained through a heart rate monitor. At the end of the time trial, participants indicated their perceived level of fatigue using the traditional Borg scale. In comparison to the placebo, caffeine intake in the form of coffee significantly reduced the time to complete the trial by 4.93 ± 4.39% (43.20 ± 7.35 vs. 41.17 ± 6.18 min; p = 0.011; effect size [ES] = 0.300). Caffeine intake reduced the time to complete four out of eight sectors with different categories of technical difficulty (p ≤ 0.010; ES = 0.386 to 0.701). Mean heart rate was higher with caffeine (169 ± 6 vs. 162 ± 13 bpm; p = 0.046; ES = 0.788) but the rating of perceived exertion at the end of the trial was similar with caffeinated coffee than with the placebo (16 ± 1 vs. 16 ± 2 a.u.; p = 0.676; ES = 0.061). In conclusion, the intake of 3 mg/kg of caffeine delivered via soluble coffee reduced the time to complete a cross-country cycling trial in recreational cyclists. These results suggest that caffeine ingested as coffee may be an ergogenic substance for cross-country cycling.

Effect of Acute Caffeine Intake on Fat Oxidation Rate during Fed-State Exercise: A Systematic Review and Meta-Analysis.

Pre-exercise intake of caffeine (from ~3 to 9 mg/kg) has been demonstrated as an effective supplementation strategy to increase fat oxidation during fasted exercise. However, a pre-exercise meal can alter the potential effect of caffeine on fat oxidation during exercise as caffeine modifies postprandial glycaemic and insulinemic responses. Hypothetically, the effect of caffeine on fat oxidation may be reduced or even withdrawn during fed-state exercise. The present systematic review aimed to meta-analyse investigations on the effect of acute caffeine intake on the rate of fat oxidation during submaximal aerobic exercise performed in the fed state (last meal < 5 h before exercise). A total of 18 crossover trials with randomised and placebo-controlled protocols and published between 1982 and 2021 were included, with a total of 228 participants (185 males and 43 females). Data were extracted to compare rates of fat oxidation during exercise with placebo and caffeine at the same exercise intensity, which reported 20 placebo-caffeine pairwise comparisons. A meta-analysis of the studies was performed, using the standardised mean difference (SMD) estimated from Hedges' g, with 95% confidence intervals (CI). In comparison with the placebo, caffeine increased the rate of fat oxidation during fed-state exercise (number of comparisons (n) = 20; p = 0.020, SMD = 0.65, 95% CI = 0.20 to 1.20). Only studies with a dose < 6 mg/kg of caffeine (n = 13) increased the rate of fat oxidation during fed-state exercise (p = 0.004, SMD = 0.86, 95% CI = 0.27 to 1.45), while no such effect was observed in studies with doses ≥6 mg/kg (n = 7; p = 0.97, SMD = -0.03, 95% CI = -1.40 to 1.35). The effect of caffeine on fat oxidation during fed-state exercise was observed in active untrained individuals (n = 13; p < 0.001, SMD = 0.84, 95% CI = 0.39 to 1.30) but not in aerobically trained participants (n = 7; p = 0.27, SMD = 0.50, 95% CI = -0.39 to 1.39). Likewise, the effect of caffeine on fat oxidation was observed in caffeine-naïve participants (n = 9; p < 0.001, SMD = 0.82, 95% CI = 0.45 to 1.19) but not in caffeine consumers (n = 3; p = 0.54, SMD = 0.57, 95% CI = -1.23 to 2.37). In conclusion, acute caffeine intake in combination with a meal ingested within 5 h before the onset of exercise increased the rate of fat oxidation during submaximal aerobic exercise. The magnitude of the effect of caffeine on fat oxidation during fed-state exercise may be modulated by the dose of caffeine administered (higher with <6 mg/kg than with ≥6 mg/kg), participants' aerobic fitness level (higher in active than in aerobically trained individuals), and habituation to caffeine (higher in caffeine-naïve than in caffeine consumers).

The Effect of Post-Activation Potentiation Enhancement Alone or in Combination with Caffeine on Anaerobic Performance in Boxers: A Double-Blind, Randomized Crossover Study.

Post-activation performance enhancement (PAPE) is a physiological phenomenon that refers to an acute excitation of the neuromuscular system following intense exercise that ends in enhanced physical performance in a subsequent bout of exercise. The scientific literature has primarily examined the effectiveness of PAPE alone or combined with caffeine (CAF) intake in all-out tests lasting ≤10 s, as the effect of PAPE is transitory. The aim of the present study was to determine the effect of a protocol to induce PAPE alone or in combination with caffeine intake on the 30 s Wingate Anaerobic Test in highly trained boxers. Twenty-five male and highly trained boxers (mean age: 20 ± 1 years) participated in a double-blind, randomized crossover study consisting of three different experimental conditions: (i) control (CON), with no substance intake and no PAPE protocol before the Wingate Anaerobic Test; (ii) PAPE + PLA, involving the intake of a placebo 60 min before and a PAPE protocol comprising a 10 s cycling sprint overloaded with 8.5% of the participants' body weight 10 min before the Wingate Anaerobic Test; and (iii) PAPE + CAF, involving the intake of 3 mg/kg of caffeine 60 min before and the same PAPE protocol used in the (ii) protocol before the Wingate Anaerobic Test. In all conditions, the participants performed the 30 s version of the Wingate Anaerobic Test with a load equivalent to 7.5% of their body weight, while the cycle ergometer setting was replicated. Immediately following the Wingate test, heart rate (HR), the rating of perceived exertion (RPE), and blood lactate concentration (Bla) were measured. In comparison to CON, PAPE + PLA enhanced mean power (p = 0.024; Effect size [ES] = 0.37) and total work (p = 0.022; ES = 0.38) during the Wingate test, accompanied by an increase in post-test blood lactate concentration (p < 0.01; ES = 0.83). In comparison to CON, PAPE + CAF enhanced mean power (p = 0.001; ES = 0.57), peak power (p = 0.013; ES = 0.57), total work (p = 0.001; ES = 0.53), post-test blood lactate concentration (p < 0.001; ES = 1.43) and participants' subjective perception of power (p = 0.041). There were no differences in any variable between PAPE + PLA and PAPE + CAF. In summary, a PAPE protocol that involves a 10 s all-out sprint 10 min before the Wingate Anaerobic Test was effective in enhancing Wingate mean power in highly trained boxers. The addition of 3 mg/kg of caffeine to the PAPE protocol produced an effect on mean power of a higher magnitude than PAPE alone, and it enhanced peak power along with participants' subjective perception of power. From a practical point of view, PAPE before exercise seems to be an effective approach for increasing Wingate performance in highly trained boxers, while the addition of caffeine can increase some benefits, especially peak power.

Influence of the time of day in the effect of caffeine on maximal fat oxidation during exercise in women: a randomized, crossover, double-blind, and placebo-controlled study.

PURPOSE: Caffeine is a stimulant with well-recognized performance and metabolic benefits, however, there is a lack of studies investigating the time-of-day influence in the properties of caffeine to enhance fat oxidation in women. Thus, the aim of the present study was to evaluate the influence of the time of the day on the effect of caffeine on the maximal rate of fat oxidation during aerobic exercise in trained women. METHODS: Fourteen female athletes (25.5 ± 7.1 years) took part in a randomized, crossover, double-blind study. All participants undertook four different experimental trials combining the ingestion of 3 mg/kg caffeine and a placebo either in the morning (8.00-10.00 h) and in the evening (17.00-19.00 h) realizing an incremental test on a cycle ergometer with 3 min stages at workloads from 30 to 70% of maximal oxygen uptake (VO2max). Substrate oxidation rates were measured by indirect calorimetry. In each trial, the maximum rate of fat oxidation (MFO) and the intensity that elicited MFO (Fatmax) were measured. RESULTS: In comparison to placebo, MFO was significantly higher with caffeine both in the morning (0.24 ± 0.13 vs 0.30 ± 0.14 g/min; p < 0.001; ES = 0.79) and in the evening (0.21 ± 0.08 vs 0.28 ± 0.10 g/min; p = 0.002; ES = 0.72). No time-of-day effect on the capacity of caffeine to increase MFO was found (all p = 0.336) CONCLUSION: The intake of 3 mg/kg of caffeine increased the use of fat as a fuel during exercise independently of the time-of-day in trained women. TRIAL REGISTRATION: The study was registered in ClinicalTrials.gov with the following ID: NCT05880186 by 15 May 2023.

Influence of a football match on landing biomechanics and jump performance in female football players.

This study aimed to assess the acute effect of a competitive football match on jump performance and kinematic parameters during jump landing in semiprofessional female football players. Twenty-two semiprofessional players (20 ± 3 years) underwent a drop jump task for a posterior video analysis of the landing phase. These measurements were obtained at (1) baseline, (2) after, and (3) 48 h after a competitive football match. A one-way ANOVA with repeated measures was employed to detect differences over the time. There was a main effect of time for maximal knee flexion angle during drop landing (p = 0.001). In comparison with baseline, maximal knee flexion angle was reduced immediately post-match and was still reduced 48 h after the match (63.4 ± 8.6 vs 57.0 ± 11.7 vs 48.9 ± 19.1, p ≤ 0.038). There was also a main effect of time for drop jump height (p < 0.001). Drop jump height was reduced immediately post-match and remained low 48 h after the match in comparison with baseline (27.3 ± 3.6 vs 24.5 ± 2.8 ~ 25.5 ± 3.0 cm, p ≤ 0.002). There was a main effect of time on hip flexion angle during landing (p = 0.001), but the pairwise comparison revealed that this variable was not affected immediately post-match but was lower 48 h after the match than at baseline (50.1 ± 10.1 ~ 50.8 ± 13.2 vs 38.1 ± 17.8 °, p ≤ 0.005). A competitive football match worsened jump performance and several landing biomechanical parameters in female football players, which were still decreased in comparison with baseline even 48 h after the match.

Reduced Match Exposure in the Previous 2 Matches Accounts for Hamstring Muscle Injury Incidence in Professional Football Players.

BACKGROUND: Hamstring strain injuries are one of the most prevalent injuries in football (soccer). We examined the influence of accumulated match-play exposure on the occurrence of hamstring strain injury in professional football from 2 teams (Spanish 1st Division, LaLiga) over 3 seasons, and determined specific cut-off points as indicators of injury risk. HYPOTHESIS: Overloaded players would be more likely to sustain a hamstring injury. STUDY DESIGN: Prospective, controlled, observational study. LEVEL OF EVIDENCE: Level 2b. METHODS: Playing time, total running distance, and high-speed running (>24 km/h) distance during official matches of players that sustained a hamstring injury were compared with uninjured, paired controls. Cumulative playing time and running performance of 4 matches before the injury was computed. Relative risk (RR) of injury occurrence was estimated by generalized estimating equations. Diagnostic accuracy was determined by receiver operating characteristics and the area under the curve. RESULTS: Thirty-seven hamstring strain injuries occurred, representing 23 ± 18 absence days per injury. Thirty-seven controls (uninjured players) were used as comparators. Low match-play exposures during 1 and 2 matches before injury were likely to explain injury occurrence (RR: 14-53%; P < 0.01). Metrics from the match before the hamstring muscle strain demonstrated the best accuracy to predict injury occurrence: high-speed running distance ≤328 m (sensitivity, 64%; specificity, 84%), playing time ≤64 min (sensitivity, 36%; specificity, 97%), and running distance ≤5.8 km (sensitivity, 39%; specificity, 97%). CONCLUSION: Relatively reduced competitive exposure in the previous 2 matches was associated with higher hamstring injury risk in professional football players. CLINICAL RELEVANCE: Screening simple metrics such as the accumulated match exposure during official matches and considering specific cut-off points for some running variables may be good indicators of injury risk and may assist in better individual injury management in professional soccer players.

Differences in playing style and technical performance according to the team ranking in the Spanish football LaLiga. A thirteen seasons study.

This study aimed to explore the differences in playing style and technical performance according to the ranking level in Spanish football teams. The sample comprised 38 professional teams that competed in LaLiga from 2008/09 to 2020/21, with a total of 4940 matches. The teams were grouped by their final ranking position: Champion (1st); Champions League (2nd-4th); Europa League (5th-6th); middle teams (7th-17th); and relegated teams (18th-20th). Linear mixed models were used to examine the effects of the team ranking on variables related to playing style and technical performance. The F2 statistic was calculated as effect size (ES). Regarding the style of play, the Champion teams initiated offensive sequences from a more advanced field position than the remaining ranking groups with a descending effect as the ranking position decreased (p < 0.001; ES = medium). The sequence duration and passes per sequence showed a decreasing effect across ranking groups (both p < 0.001; ES = small). In contrast, the direct speed showed an increasing effect as the ranking position decreased (p < 0.001; ES = small). A decreasing effect was observed in the number of sequences ending in the final third as the ranking position decreased (p < 0.001; ES = large) while no effect was found for the sequences ending in a shot. There was a reduction effect in ball possession, passing accuracy, through balls and crosses as the teams' ranking decreased (all p < 0.001; ES = small-to-large). In summary, higher-ranked teams had an advanced starting position, longer offensive sequences, slower progression speed, more ball possession, higher passing accuracy, and more crosses and through balls than lower-ranked teams. Football coaches should consider that adopting a playing style focused on regaining the ball possession in advanced field zones and using long passing sequences can be an effective tactical strategy to improve the teams' ranking during the season.

Research Trends in the Effect of Caffeine Intake on Fat Oxidation: A Bibliometric and Visual Analysis.

In the last few decades, numerous studies pertaining to research groups worldwide have investigated the effects of oral caffeine intake on fat oxidation at rest, during exercise, and after exercise. However, there is no bibliometric analysis to assess the large volume of scientific output associated with this topic. A bibliometric analysis of this topic may be used by researchers to assess the current scientific interest in the application of caffeine as a nutritional strategy to augment fat oxidation, the journals with more interest in this type of publication, and to draw international collaborations between groups working in the same area. For these reasons, the purpose of this study was to assess the research activity regarding oral caffeine intake and fat oxidation rate in the last few decades by conducting a bibliometric and visual analysis. Relevant publications from 1992 to 2022 were retrieved from the Web of Science (WoS) Core Collection database. Quantitative and qualitative variables were collected, including the number of publications and citations, H-indexes, journals of citation reports, co-authorship, co-citation, and the co-occurrence of keywords. There were 182 total publications, while the number of annual publications is saw-shaped with a modest increase of 11.3% from 2000 to 2009 to 2010 to 2019. The United States was the country with the highest number of publications (24.17% of the total number of articles), followed by the Netherlands (17.03%). According to citation analyses, the average number of citations per document is 130, although there are 21 documents that have received more than 100 citations; the most cited document reached 644 citations. These citation data support the overall relevance of this topic in the fields of nutrition and dietetics and sport sciences that when combined harbored 85.71% of all articles published in the WoS. The most productive author was Westerterp-Plantenga with 16 articles (8.79% of the total number of articles). Nutrients was the journal that published the largest number of articles on this topic (6.59% of the total number of articles). Last, there is a tendency to include keywords such as "performance", "carbohydrate", and "ergogenic aid" in the newer articles, while "obesity", "thermogenic", and "tea" are the keywords more commonly included in older documents. Although research into the role of caffeine on fat oxidation has existed since the 1970s, our analysis suggests that the scientific output associated with this topic has progressively increased since 1992, demonstrating that this is a nutritional research area with a strong foundational base of scientific evidence. Based on the findings of this bibliometric analysis, future investigation may consider focusing on the effects of sex and tolerance to caffeine to widen the assessment of the effectiveness of oral caffeine intake as a nutritional strategy to augment the use of fat as a fuel, as these terms rarely appear in the studies included in this analysis. Additionally, more translational research is necessary as the studies that investigate the effect of oral caffeine intake in ecologically valid contexts (i.e., exercise training programs for individuals with excessive adiposity) are only a minor part of the studies on this topic.