Journal of Sports Medicine and Physical Fitness最新文献

Background: This investigation aimed to dissect the kinematic differences in sprinting between high-speed treadmill and overground conditions, examining how these variations are influenced by the athlete's training status and biological sex.

Methods: A total of 40 participants, 20 NCAA Division 1 sprinters and 20 recreational runners, performed a series of maximal sprints on a high-speed treadmill and on a standardized competition overground track. Sprinting kinematic variables such as stride length, stride frequency, contact time, and flight time were collected via photoelectric sensors. Maximal sprinting kinematics were analyzed by linear mixed-effects models, considering the impacts of sprinting environment (treadmill vs. overground), training level, and sex, with leg length as fixed factors and individual athletes as random effects. Statistical significance was set at a significance level of 0.05.

Results: The statistical analysis revealed that high-speed treadmill sprinting significantly affects all measured kinematic variables, leading to increased stride frequency and contact time. Elite sprinters demonstrated enhanced kinematic efficiency over recreational runners, characterized by increased stride length and frequency and reduced contact time. Sex-based kinematic distinctions also emerged, with male athletes exhibiting superior stride length and frequency compared to female athletes. Leg length significantly influenced stride frequency, and an interaction effect was observed for flight time between sprint type and athletic group.

Conclusions: These findings elucidate the distinct biomechanical profiles across sprinting modalities and athlete demographics, emphasizing the need for sprint training customization. This study's insights offer a valuable reference for coaches and athletes to refine training and performance assessment in varied sprinting environments.

Introduction: The gluteus medius (GMED) and gluteus maximus (GMAX) play a crucial role in postural control, and postural control is impaired in individuals with chronic ankle instability (CAI). However, the association between CAI and the recruitment of these muscles remains unclear. The purpose of this study was to explore the contractile thickness of GMED and GMAX during functional movements in individuals with CAI compared to healthy controls.

Evidence acquisition: A systematic search was conducted in six databases (PubMed, Embase, Cochrane Library, Web of Science, EBSCO, and PEDro). Included studies involved the contractile thickness of GMED and/or GMAX comparing CAI with non-CAI. The extracted data were subjected to meta-analysis for observing the differences between the two. The correlation and difference in contraction between GMED and GMAX were analyzed using the Pearson Correlation Coefficient (PCC) and t-test, respectively.

Evidence synthesis: Six studies with 176 participants were found. Contractile thickness measured by ultrasound showed GMED thickness change to be lower in CAI than in controls during functional movements and exercise (WMD: -0.08; 95% CI: -0.11, -0.04; P<0.00001). There was no significant difference between the two groups with respect to contraction of GMAX (WMD: 0.02; 95% CI: -0.01, 0.05; P=0.25). The PCC and P value (t-test) between the ratio of contractile thickness of GMED and GMAX in CAI were 0.397 and 0.029 respectively, indicating activity differences.

Conclusions: CAI may be associated with weaker GMED recruitment during functional movements and exercise, but the activation of GMAX in CAI may be unaffected.

Background: Pacing strategies during endurance efforts vary depending on athlete experience, race length, and terrain. In ultramarathon trail running the specific race route profile can have a significant impact on optimal pacing strategy. The aim of this study was to determine the relationship between uphill, downhill and level running with overall performance and to compare the difference in pacing strategies between top 10 (TOP-10) and non-top 10 (NOT TOP-10) finishers of a 100-km ultra-trail marathon with +5000-m elevation gain.

Methods: Fifty male finishers (TOP-10: N.=6, NOT TOP-10, N.=44) and forty-six individual segments (1.5±1.2 km) were analyzed based on 2021 100-km UTCT STRAVA data. Relative segment speed and CV% were used to identify pacing strategies. Spearman Rank and Mann-Whitney U Tests were used to analyze the data. Significance was set at P<0.05.

Results: Uphill running had the strongest relationship with overall performance (r=0.826, P<0.01). Substantially weaker relationships between overall running performance and level (r=0.402, P<0.01) and downhill (r=-0.382, P<0.01) running performance were found. The CV% was significantly lower in TOP-10 (32.10±1.81) than NOT TOP-10 (35.39±4.43) (U=24, r=0.46, P<0.01).

Conclusions: Uphill running performance remains a valuable measure of overall trail running performance as it represents a higher percentage of overall running demand. TOP-10 runners have diminished decay in initial running speed than NOT TOP-10 runners, despite a generally high variation in pace and net positive split in ultra-trail running.

Background: Treadmills have been used in laboratories to assess various measures related to walking and running. However, there has been some skepticism regarding their reliability as a representation of outdoor running. While marathon running has gained popularity as a form of physical activity, there have been few studies examining stride-to-stride variability after distance running, especially in relation to the duration and surface of running. This study compared stride time and lower limb joint angles during distance treadmill running and running over-ground. The hypothesis was that stride-to-stride variability would be influenced by running duration and surface, with greater variability observed during outdoor running.

Methods: Eleven runners participated in the study, running on a treadmill and over-ground for 31 minutes at their preferred speed. Inertial measurement units were used to measure stride time, total range of motion, and joint angles of the hip, knee, and ankle in different phases of the gait cycle in the sagittal plane movements. Mean and coefficient of variation of each parameter were compared between the initial and final 5 minutes of running on the treadmill and over-ground.

Results: There were no significant differences in stride time or its variability based on running duration or surface. However, mean and variability of certain lower limb joint angles were higher during outdoor running, supporting the hypothesis. Variability was higher in the initial duration of running as compared to final phase of running.

Conclusions: These findings suggest that treadmill may not fully reflect the dynamics of running over-ground. It is important to consider variability in gait analysis and research, as well as the potential impact on training and clinical practice.

Background: Central Augmentation Index (AIx) is a surrogate marker of large artery stiffness that may provide valuable insight to cardiovascular health. The aim of this study was to evaluate the relationship between AIx and components of physical fitness.

Methods: One hundred eighty-five healthy men and women (aged 20-79 years) underwent non-invasive assessment of arterial wave reflection to determine AIx, which was corrected to a heart rate of 75 beats per minute (AI×75). Body composition was evaluated using dual energy X-ray absorptiometry (DXA) and aerobic capacity (VO2max) was derived from expired gas analysis during a symptom limited exercise test on a treadmill.

Results: A multiple linear regression revealed age and VO2max as significant predictors of AI×75 [AI×75=32.055 + (0.252×age) - (0.722×VO2max)]. Upon removal of VO2max from regression analysis, resting heart rate (RHR) and % body fat (BF%) were revealed to be significant predictors of AI×75: AI×75=-61.316 + (0.481×age) + (0.565×BF%) + (0.56×RHR).

Conclusions: Our findings demonstrate that central Augmentation Index can be reliably predicted in healthy adults who undergo a maximal exercise or body composition assessment. These prediction equations may be applied in non-medical settings to assist in creating comprehensive health and fitness profiles for healthy clientele.

Background: Anxiety commonly affects older individuals with negative consequences on various physical and motor performances such as balance. When coupled with age-related muscular strength loss, the effects on the ability to perform daily tasks could be particularly detrimental, particularly in older women who are more susceptible to anxiety, muscular strength losses and falls. The study aimed to verify the effects of anxiety on balance performance in relation to muscular strength level in healthy older women.

Methods: Twenty-six individuals aged over 64 years underwent tests for anxiety, static and dynamic balance, and hand-grip strength. Two-way ANOVA was performed with anxiety (anxious vs. non-anxious) and strength (high vs. low) as independent variables.

Results: A significant main effect of anxiety and a significant interaction anxiety*strength for static balance were observed. The analysis of the interaction revealed a significant effect of anxiety on the non-preferred one-foot balance with differences between low and high strength subjects; for low levels of strength, anxious woman performed significantly better than non-anxious, for high levels of strength, anxiety had no effect.

Conclusions: Moderate levels of anxiety may support balance performance in low strength condition. These findings if further verified on larger samples could add important information on the role of anxiety on motor performance in aging.

Background: To gain optimal positioning to make sure the game laws are applied in uniform way, the performance of field referee must be periodically evaluated to have constantly adequate training during a match and during the competitive season. Considering that field Yo-Yo Intermittent Recovery Test-Level 1 is frequently employed in elite team sport players to estimate maximal oxygen uptake (VO2max) in field settings, the aim of this cross-sectional, gender-comparative study was to develop a new adjusted Yo-Yo-1 equation for estimating VO2max in football referees.

Methods: During off-season, 20 male (21.2±3.6 yrs) and 20 female (22.5±4.6 yrs) sub-elite football referees underwent laboratory treadmill test and Yo-Yo-1.

Results: VO2max during Yo-Yo-1 and laboratory treadmill test were significantly correlated in the whole sample (r=0.871; P<0.0001), women (r=0.861; P<0.0001) and men (r=0.800; P<0.0001). Only in women VO2max during Yo-Yo-1 was lower than laboratory treadmill test (-4.3%; P=0.014). Adjusted formulae (pooled and gender-based) allowed to mitigate the underestimated values of laboratory treadmill test of VO2max found with the Bangsbo's equation (pooled sample: -14.9%, P<0.0001; women: -13.2%, P<0.0001; men: -16.4%, P<0.0001).

Conclusions: Adjusted Yo-Yo-1 equations allow to accurately monitor changes in cardiopulmonary performance, and based on this, administer constantly adequate training loads, in male and female field referees.

Introduction: When exercising to preferred music (PM), participants found more satisfaction and less typical exercise-related fatigue, which made it easier and more enjoyable to maintain the physical activity (PA) until the exercise goals were achieved. The purpose of this review and meta-analysis was to determine whether changes on internal training load in adult recreational athletes were modified by listening to PM and non-preferred music (NPM), during different PA.

Evidence acquisition: A music-focused search was performed on the Google Scholar, PubMed, and Web of Science databases to identify relevant articles to this topic published after 2000 to investigate the effects of PM on psychophysiological responses to PA.

Evidence synthesis: Twelve studies met the inclusion criteria and were included in the qualitative analysis. The research studies' sample sizes varied from ten to twenty-five participants. Heart rate (HR) and rate of perceived exertion (RPE) on internal training load were the selected indicators. The use of different kinds of music had mostly, non-significant effects on HR and RPE toward the ability of music to allow participants to dissociate from the intensity level they are experiencing.

Conclusions: The meta-analysis confirmed that preferred music had no significant effect on HRmean or RPE. The results of this review contradict the idea that listening to music improves exercise performance.

Background: Understanding the dietary intake of elite adolescent athletes and its adequacy with sport nutrition recommendation is a key issue for health and player development, as well as performance and recovery. Energy availability needs to be considered to ensure optimal health and performance in young athletes. The present study aimed to quantify energy availability, energy expenditure and macronutrient intake in young male rugby union players competing at national level.

Methods: Twelve male adolescent players (15.6±0.6 years) completed a 7-days prospective observational study (5 days of training and 2 days of full recovery). Total energy expenditure was estimated using indirect calorimetry and heart rate measurement. Energy intake was assessed using weighed food by a dietitian in cafeteria (training days) and image-based dietary (recovery days). Energy availability was calculated using (energy intake-exercise energy expenditure)/fat-free mass.

Results: Mean energy availability was 38.5±7.5, 40.2±5.4 and 47.8±5.1 kcal/kgFFM/d on heavy training, moderate training and recovery days, respectively. Players consumed a low carbohydrate (~5.0 g/kg/d), high protein (~2.0 g/kg/d) and high fat (~1.8 g/kg/d) diet on training and recovery days in relation to current international nutritional recommendations for young athletes.

Conclusions: Athletes showed sub-optimal energy availability on training days, high energy availability on recovery days and did not comply with carbohydrate intake recommendations on training nor recovery days. These results highlight the short-term inadequacy of energy availability as a result of low carbohydrate intake, warning about the possible adverse short-term metabolic effects on health and performance of young athletes.