Journal of Sports Medicine and Physical Fitness最新文献

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.

Background: Soccer is an intermittent team sport that demands high aerobic capacity. On field, soccer players' aerobic capacity, assessed through the maximal oxygen uptake (VO2max), is usually determined by an intermittent recovery test. The aim of this study was to obtain a construct validity of a new intermittent recovery test (IRT) with a fixed speed and a progressive decrement of rest period.

Methods: Twenty-five male soccer players were recruited to perform an incremental continuous test (ICT) and the new IRT, to compare their physiological data. Fifteen male soccer players were involved to perform a test-retest of IRT to assess its reliability.

Results: VEpeak, absolute VO2max, relative VO2max and VCO2peak registered during ICT and IRT correlated strongly (Pearson's correlation coefficient ranges from 0.75 to 0.80, with very large as magnitude of effects and with P<0.001). IRT showed reliability from good to excellent regarding VEpeak, absolute VO2max, relative VO2max, VCO2peak and covered distance (ICC values ranged from 0.82 to 0.95).

Conclusions: These findings and its underlying physiological and muscular demands, suggest that IRT can be considered as a valid and reliable test to assess aerobic capacity in soccer players during the competitive period.

The detection of myocardial scar tissue profoundly influences athletes care and prognostic categorization. Athletes appear to be at risk of developing fatal arrhythmias when harboring a quiescent cardiac disorder. Early identification of disease in asymptomatic individuals through preparticipation screening is means to prevent these events. We presented a male marathon runner master athlete who came at our Department of Sports Medicine for a preparticipation screening. Baseline 12-lead standard electrocardiogram was normal. A maximal cycle ergometer exercise test revealed exercise-induced premature ventricular contractions (PVCs) with uncommon morphology. Echocardiography revealed an hyperechogenic zone at mid-basal posterior segments of the left ventricle. Twenty-four-hours ECG Holter monitoring, with training session, showed some isolated polymorphic PVCs even during training session. Cardiac magnetic resonance (CMR) confirmed the presence of a non-ischemic left ventricular scar (subepicardial) into the mid-basal segment of the posterior wall. Echocardiography is a first-line, economic, and accessible diagnostic test for athletes and it can be useful, when abnormalities are detected, to indicate further investigations, such as CMR. Although non-ischemic left ventricular scarring is difficult to detect on echocardiography, this event is sometimes possible and require further investigation when observed.

Background: Understanding the evolution of morphological features and their relationship with physical performance may assist coaches and institutions in developing the next generation of beach volleyball (BV) athletes for senior-level competition. Thus, this study analyzed the morphological features of Brazilian BV athletes by sex among age groups, and their relationship with physical performance.

Methods: A cross-sectional design was used to evaluate Brazilian BV players of both sexes in the U15 (11-14 years old, N.=21), U18 (15-17 years old, N.=21) and Senior (≥18 years old, N.=19) categories. The players underwent a series of kinanthropometric tests, including morphological (anthropometry, body composition and somatotype), neuromuscular (flexibility, handgrip strength, vertical jump [VJ], agility, and 5-m and 10-m maximum-speed sprints), and metabolic (VO2max) measurements. Welch analysis of variance (ANOVA) was used to compare the categories and the relationship between morphological and physical performance features was analyzed using Pearson's coefficient (r).

Results: Significant differences were found among the categories for female (body mass, skeletal muscle mass, hamstring flexibility, handgrip strength [HGS]) and male (body mass, height, BMI, skeletal muscle mass, flexibility, HGS, vertical jump, agility, maximum-speed sprints, and VO2max) players. Moreover, moderate, and strong correlations were identified between morphological features and physical performance (-0.90≤r≤0.89).

Conclusions: The morphological and physical performance features of BV athletes varied among the U15, U18, and Senior categories, as expected due to their physical training process. Additionally, there are several morphological features that are correlated with physical performance, but the magnitude seems to depend on sex and category.

Background: We recently have reported that individual day-to-day arterial stiffness variations are associated with maximal aerobic capacity. However, the evidence of this phenomenon was not provided sufficiently. The present study aimed to examine whether a decrease in arterial stiffness through static stretching exercise could enhance maximal aerobic capacity.

Methods: Twelve healthy young men (age 22±2 years, mean and standard deviation) participated in this study and underwent two separate sessions in a randomized controlled crossover design: a single session of a whole-body static stretching exercise protocol that involved the trunk, upper limb, and lower limb (stretch condition), and sedentary control where they rested in the exercise room. Brachial-ankle pulse wave velocity (baPWV) was measured as an index of systemic arterial stiffness before, immediately after and at 30 min after both conditions. Maximal oxygen uptake (V̇O2max) was assessed using a graded power test on an electronically braked cycle ergometer after these measurements.

Results: As we expected, there was a significant decrease in the baPWV at 30 min after the stretch trial compared to baseline values (P=0.01). The baPWV in the stretch condition was lower than that of the control condition, while V̇O2max in the stretch condition was higher than that of the control condition (P=0.03).

Conclusions: Based on these findings, it can be inferred that an acute reduction in arterial stiffness may contribute to change in maximal aerobic capacity.

Background: The anthropometric characteristics of adolescent basketball athletes can determine their ability to produce muscle power. Lack of physical activity (PA) level or an increased sedentary life seem to be associated with the overall health status and the occurrence of knee injuries. The aim of this paper was to identify possible correlations between anthropometric characteristics, body composition, exposure time to electronic devices or screen time (ST), and PA level along with muscle power and dynamic knee valgus (DKV) in young basketball athletes.

Methods: Anthropometric and demographic characteristics were recorded. PA level was assessed through the International Physical Activity Questionnaire, and ST was assessed through a single question from the HELENA study. The Counter Movement Jump test was used for the evaluation of the lower limb muscle power, while the Single Leg Drop Jump test was used for the evaluation of the DKV via two-dimensional (2D) kinematic analysis.

Results: One hundred twenty-five adolescent basketball athletes (66.4% boys), 12 to 17 years old (13.94±1.58 years) participated. The Pearson index showed a statistically significant positive correlation between muscle power and height (r=0.788, P<0.001), while the Spearman Index showed a more minor but equally statistically significant positive correlation with Body Mass Index (rs=0.651, P<0.001) and age (rs=0.579, P<0.001). The ST (rs= -0.194, P=0.03) showed a weak negative correlation with DKV, while PA (r=0.85, P<0.001) showed a high, statistically significant, positive correlation.

Conclusions: A high level of PA could play a key role in compensating and thus reducing the negative effects of high exposure to ST on the DKV.

Background: Exposure to hypoxia immediately challenges a variety of physiologic systems that limit exercise capacity. Under normoxia, caffeine (CAFF) increases ventilation and subsequent oxygenation of hemoglobin (SpO2) and skeletal muscle (SmO2). CAFF improves exercise performance at altitude. However, little attention has been given to submaximal exercise in hypoxia, particularly regarding low CAFF consumers and female participants. The aim of this study was to determine the effect of CAFF on pulmonary, metabolic, and perceptual variables in response to submaximal running in hypoxia in low CAFF consuming males and females.

Methods: In a double blinded, counterbalanced design, 14 (6 females) individuals (24.1±5.1 years; VO2max: 40.6±5.6 mL × kg^-1 × min^-1; 20.8±8.0% body fat), who habitually consumed ≤150 mg/day of CAFF performed treadmill running at workloads of 25%, 40%, 60%, and 75% of sea level VO2max in normobaric hypoxia (FIO2=0.15) on two separate occasions: 1) 60 minutes after 6 mg/kg of CAFF; or 2) placebo.

Results: CAFF had no effect on any variable measured. Specifically, VE (condition: P=0.12; interaction: P=0.19), VT (condition: P=0.16; interaction: P=0.57), and Ve:VO2 (condition: P=0.07; interaction: P=0.69) were similar between groups. Further, CAFF had no effect on relative VO2 (condition: P=0.84; interaction: P=0.95), HR (condition: P=0.28; interaction: P=0.35), SmO2 (condition: P=0.66; interaction: P=0.82), or SpO2 (condition: P=0.16; interaction: P=0.97). Finally, rating of perceived exertion (RPE; P=0.92) and acute mountain sickness scores (P=0.29) were similar across conditions.

Conclusions: These data demonstrate that CAFF provides no physiologic advantage to submaximal exercise in acute, normobaric hypoxia with low CAFF consuming males and females.

Background: Sport-related concussions (SRC) represent a significant concern for athletes. While popular contact sports such as football and soccer have been the focus of much SRC research, wrestling has received comparatively little attention. The current study aimed to: 1) describe the mechanisms of injury leading to SRC in wrestling; and 2) compare recovery outcomes based on mechanism of injury.

Methods: A retrospective, cohort study of wrestlers aged 12-18 who sustained a concussion between 11/2017-04/2022 was performed. Contact mechanism was defined as what initiated contact with the athlete's head/body. Player mechanism was defined as the activity the injured athlete was performing when the concussion occurred. Recovery outcomes were compared using Mann-Whitney-U Tests and multivariable regression analysis.

Results: Seventy-three (age=15.8±1.4 years; boys=73 [100.0%]) wrestlers were included. SRCs occurred more often in competition than in practice (66.2% vs. 33.8%, respectively). Head-to-ground/wall (56.2%) and takedown (58.9%) were the most common contact and player mechanisms, respectively. Bivariate analysis showed that head-to-head/body SRCs had longer time to symptom resolution compared to head-to-ground/wall SRCs (23.0 [14.8-46.5] vs. 14.0 [6.0-30.0] days; U=149.00, P=0.029), though the difference did not persist in multivariable analysis. For player mechanism, non-takedowns SRCs had longer time to symptom resolution than takedown SRCs (15.0 [6.0-24.0] vs. 28.5 [13.0-49.3]; U=166.5, P=0.019), but the difference also did not persist in multivariable analysis. Bivariate analysis revealed no significant difference in RTL between takedown and non-takedown SRCs (3.0 [2.0-6.0] vs. 4.0 [1.5-7.0]; U=484.50, P=0.708); however, in multivariable analysis, takedown SRCs were associated with longer RTL (β=0.23, 95% CI: 0.02, 9.27; P=0.049).

Conclusions: The current study found that SRCs occurred more commonly during competitions, and head-to-ground/wall and takedown were the most common contact and player mechanism, respectively. SRCs that occurred during takedowns were associated with longer RTL.

Background: The aim of this study is to study the clinical decision-making practice of Italian physiotherapists in return to running (RTR) after anterior cruciate ligament (ACL) reconstruction, and the differences in decision-making in relation to physiotherapist's characteristics.

Methods: An online survey was developed, 1404 physiotherapists were contacted by email, via chartered association, or via social media.

Results: Most respondents (83%) indicated that the RTR decision should be made by a multidisciplinary team with RTR clearance around 3-4 months after surgery (47%). The most important criteria guiding the RTR decision were knee flexion range of motion (ROM) >130° (50%), complete extension ROM (95%), no pain (45%) and no effusion (68%). A Limb Symmetry Index (LSI) >70% for quadriceps (49%), hamstring (48%) and LSI >90% for posterolateral hip (45%) and triceps surae strength (42%) should be achieved for RTR. Approximately half of the participants (49%) do not consider ACL laxity tests to be used for RTR decisions. Response differences were found between sample subgroups. More experienced physiotherapists and those with post graduate training had lower thresholds to clear RTR.

Conclusions: Experienced physiotherapists who treated a higher number of patients after ACL reconstruction, who had certified specialist training and a specific interest towards ACL rehabilitation, generally reported clinical practice modalities more in line with current evidence.

Background: There is conflicting evidence regarding the presence and magnitude of exercise-induced muscle damage (EIMD) following low-load resistance training with blood flow restriction (LL+BFR), which may be related to the protocol implemented or exercise volume. Therefore, the purpose of this investigation was to examine the effects of a 75 repetition (BFR-75) (1×30, 3×15) and four sets to volitional failure (BFR-4x) protocols on indices of EIMD among untrained men.

Methods: Twelve males with no history of lower-body resistance training during the previous six months volunteered for this investigation. One leg was randomly assigned to BFR-75, and the other to BFR-4x. Participants performed isokinetic, unilateral, concentric-eccentric, leg extension muscle actions at 30% of maximal strength with BFR. Indices of EIMD (limb circumference, perceived muscle soreness, pain pressure threshold [PPT], passive range of motion, and maximal strength [MVIC]) were recorded before exercise and 0, 24, 48, 72, and 96-hours post-exercise for each protocol.

Results: There were no significant changes (P>0.05) in limb circumference, PPT, passive range of motion, or MVIC. For both BFR-75 and BFR-4x, perceived muscle soreness increased (P<0.001) similarly 24- (2.5±1.7 AU) and 48-hours (1.9±1.7 AU) post-exercise.

Conclusions: There was an increase in muscle soreness 24-48 hours post-exercise for both conditions, which may be due to metabolic stress, but this did not affect the force-generating capacity of the muscle (MVIC), suggesting minimal EIMD. The conflicting evidence of EIMD following LL+BFR may be related to differences in restriction time or overall exercise time.