Frontiers in Sports and Active Living最新文献

Introduction: Anterior cruciate ligament (ACL) injuries represent the most prevalent type of knee injury, with surgical reconstruction being the prevailing treatment modality. However, postoperative pain and muscle weakness are common occurrences. Blood flow restriction (BFR) training has demonstrated potential in enhancing muscle adaptation and reducing pain; nevertheless, its efficacy in the early postoperative period following ACL reconstruction remains to be determined. The present study investigates whether the incorporation of BFR into low-load strength training confers additional clinical benefits in comparison to low-load exercise alone.

Methods: A total of 30 patients (24 male, 6 female) with a mean age of 32.3 (± 12.4) years were included in the study. All patients had undergone primary ACL reconstruction with a semitendinosus graft and standardized fixation techniques. They were randomised to receive either low-load strength training with (LL-BFR) or without BFR (LL). The interventions consisted of four sets of leg press exercises (30 repetitions for the first set, 15 for subsequent sets) performed twice a week for four weeks, starting four weeks postoperatively, as an adjunct to standard rehabilitation protocols. The primary outcome measure was pain perception, which was assessed by pressure pain thresholds (PPT) and a visual analogue scale (VAS) for knee pain at rest and during a functional stair-climbing test. We further included strength and functional measurements.

Results: Mixed linear models were employed for the statistical analysis. No statistically significant differences between groups were observed for the primary or secondary outcome measures. Only, significant time effects were found for both groups for subjective pain (rest p < 0.001, stairs p = 0.003); maximum strength (p = 0.002); active (ext. p = 0.035, flex. p < 0.001) and passive range of motion (ROM) (ext. p = 0.029, flex. p < 0.001) on the affected side and International Knee Documentation Committee (IDKC) scores (p < 0.001).

Discussion: The present study shows that a combination of BFR and low-load strength training does not provide additional clinical benefits to low-load training alone in the early postoperative phase, following ACL reconstruction in our study group. Further research is required to explore the potential efficacy of BFR in specific patient subpopulations, with different training loads or at later stages of rehabilitation.

Sports coaching is a highly stressful profession due to the variety of responsibilities and expectations placed on coaches. The purpose of this study was to assess the sources of this stress among sports coaches in South Africa. The sample consisted of 449 sports coaches (age: 34.6 ± 6.21 years; 274 males and 175 females) who volunteered to participate in the study by responding to the Stressors in Sports Coaching Questionnaire. The results showed that the most important environmental stressors encountered by sports coaches were "condition of playing surface" (M = 4.00, SD = 0.89), "poorly planned travelling arrangements" (M = 4.45, SD = 0.80), "distraction while training and/or competing" (M = 4.46, SD = 0.81), "job insecurity" (M = 4.49, SD = 0.81), and "unsafe competition arena" (M = 4.15, SD = 0.68). The major performance-related stressors faced by sports coaches were "being blamed for poor results" (M = 4.09, SD = 0.72) and "high expectation to win" (M = 4.23, SD = 0.87). Of the task-related stressors, "performing multiple roles (selection, scouting, etc.)" (M = 3.93, SD = 0.71) and "making an important decision which later I realised was wrong" (M = 3.95, SD = 0.78) were reported as most important. These results emphasise the need for coaches to develop psychological skills to help manage the many demands of coaching and thus reduce their stress levels.

Background: Water-based exercise augments exercise-induced increases in brain blood flow, optimizing a proposed key mechanistic pathway for improved brain health. Aquatic treadmill exercise has been shown to aid gait re-education of stroke survivors, however its potential to enhance cerebrovascular function in this clinical population has not been tested. This pilot study aimed to examine the feasibility and preliminary efficacy of a 4-week aquatic treadmill (ATM) training intervention on cerebrovascular responsiveness and gait function in stroke survivors.

Methods: Six community-dwelling stroke survivors (58 ± 11 years, 8 ± 11 years post stroke) completed a 4-week ATM intervention, consisting of 20-30 min sessions, 3 times/week. Pre- and post-intervention measures were taken of cerebrovascular reactivity (CVR), indexed via changes in middle cerebral artery blood velocity (MCAv) to a hypercapnic (5% CO₂ in air) stimulus. Changes in mobility were assessed via 10-metre walk, Timed-Up-And-Go, and 6-minute walk (6MW) tests.

Results: Adherence to the intervention was excellent, with 70 of the 72 (97%) available training sessions completed by participants. CVR increased on average by 44% (95% CI: ±58%; 2.8%-4.0%ΔMCAv/mm Hg ΔPETCO₂) in the stroke-affected hemisphere and 48% (95% CI: ±41%; 3.0%-4.5%ΔMCAv/mm Hg ΔPETCO₂) in the unaffected hemisphere post intervention, although changes did not reach statistical significance (p = 0.218; Friedman's test). Within-group gait improvements were seen in speed and distance, with some changes above clinically meaningful thresholds; although this was not uniformly evident.

Conclusion: This pilot study established ATM training as a feasible option for some patients in stroke rehabilitation. Despite the limited sample size, the study demonstrated promising enhancements in cerebrovascular function, with preliminary evidence suggesting concurrent improvements in gait performance. Well-designed, larger studies are warranted.

Introduction: Historical training methodologies in endurance running provide valuable insights for contemporary sports science. Mihály Iglói's interval-based system, highly influential between the 1950s and 1970s, produced numerous world records yet remains only partially understood. This study reconstructs Iglói's approach through historical sources, contextualizes it within modern theory, and evaluates its relevance to current elite distance running practices.

Methods: A narrative approach was applied, combining Hungarian and English archival sources with a comparative review of contemporary peer-reviewed literature on international-level distance running training. Data synthesis identified continuities, divergences, and adaptable elements of Iglói's methodology.

Results: Iglói advanced Gerschler's intervals into a complex, high volume system with up to 13 interval sessions per week. Training was primarily based on effort-based short repetitions (100-400 m), complemented by race-specific longer repetitions (600-1200 m). Sessions were organized into sets and sub-sets, interspersed with active recoveries and shakedown strides, while particular emphasis was placed on running form. The system was flexible and individualized, adapting to athletes' goals and event demands. Under this framework, athletes achieved 31 world records and numerous national titles.

Discussion: Contemporary distance running training again heavily focuses on controlled longer and shorter aerobic intervals for improving lactate threshold speed (vLT2). From Iglói's system, re-adaptable elements include race speed-specific but controlled short intervals for aerobic conditioning, combined with harder repetitions, alongside the use of active recoveries and "flush" or recovery sets to enhance lactate shuttle mechanisms. Equally important is the emphasis on economic running form at different parts of the race, supporting both efficiency and tactical readiness.

Background: Decreasing physical activity levels present a major public health challenge. The use of e-bikes has risen substantially over the past decade, presenting a potential solution to common barriers associated with physical activity and conventional cycling. However, the intensity of e-bike commuting in real-life settings remains unknown. This study aimed to investigate the self-selected intensity and the impact of topography on intensity during regular e-bike commuting.

Methods: In this cross-sectional study, oxygen consumption, power output, heart rate, perceived exertion, and positional data were recorded from 19 commuters [mean (standard deviation) age 41 (8) years] during their regular commutes on their own e-bikes. Data were summarized and analyzed in 10, 30, and 60 s epochs, and adjusted for the duration of the commutes. Intensity of the commutes was compared between downhill, flat, or uphill segments using linear mixed models. The intensity of physical activity was defined as light <3 metabolic equivalents (METs), moderate 3-5.9 METs, or vigorous ≥6 METs.

Results: Oxygen consumption during e-bike commuting was mean (standard deviation) 20.8 (5.0) mL/kg/min [5.9 (1.4) METs]. Depending on epoch lengths, 44%-48% of the commutes were classified as vigorous physical activity. Across epoch lengths, the mean intensity of the commutes was classified as moderate (4.6-4.8 METs) during downhill, moderate (5.5-5.9 METs) during flat, and vigorous (7.0-7.5 METs) during uphill riding (p < 0.001).

Conclusions: Our findings suggest that e-bike commuters self-selected moderate to vigorous intensities during real-life commutes, aligning with international physical activity guidelines for improving public health. Therefore, policies promoting a shift from car use to e-biking could have significant public health benefits.

This study examined the relationships among lower-limb strength, power, and horizontal ground reaction force (GRF) during change of direction (COD) tasks in elite female basketball players. Sixteen athletes completed an isometric mid-thigh pull (IMTP), a countermovement jump (CMJ), a lateral shuffle, and 180° turns. For the COD task, the turning distance was individualized based on each participant's standing height. Dual portable uniaxial force-plates were used to measure IMTP peak force and the rate of force development (RFD) over 0-200 ms (RFD₂₀₀) and 0-250 ms (RFD₂₅₀). CMJ jump height and phase-specific peak power (braking and propulsive) were also quantified, with all variables normalized to body mass. Horizontal GRFs during plant-foot contact in the COD tasks were recorded using triaxial force-plates, and both peak and mean GRF relative to body mass were analyzed. Mean horizontal GRF during both the lateral shuffle and the 180° turn showed consistent, significant positive correlations with IMTP peak force (r = 0.56-0.80, all p < 0.05). In contrast, correlations between mean horizontal GRF and IMTP RFD were limited, reaching significance only during the right lateral shuffle (RFD₂₅₀: r = 0.51, p = 0.04) and the left 180° turn (RFD₂₀₀ and RFD₂₅₀: both r = 0.68, p < 0.01). Peak horizontal GRF showed negligible associations with most IMTP or CMJ variables, except for IMTP peak force during the left 180° turn (r = 0.51, p = 0.045). Associations with CMJ metrics were modest; jump height correlated significantly with mean horizontal GRF only during the right lateral shuffle (r = 0.50, p = 0.047), whereas CMJ peak braking and propulsive power showed no significant relationships. These findings emphasize the importance of maximal isometric strength for COD performance in this population and highlight the need to select assessment indices aligned with the task-specific demands of strength and conditioning programs.

Objectives: To evaluate the scientific validity of the International Olympic Committee's (IOC) 2021 framework principle of "No Presumption of Performance Advantage," which suggests that circulating testosterone levels alone does not confer a competitive advantage.

Design: A critical review of existing scientific literature concerning the physiological effects of testosterone and male puberty on athletic performance, complemented by a forward-looking proposal for integrating multi-layered biological and performance data.

Method: Relevant peer-reviewed studies were examined, focusing on the role of endogenous testosterone, the long-term effects of male puberty, and performance outcomes among transgender women and athletes with differences in sexual development (DSD). Emphasis was placed on strength, power, and endurance metrics. In addition, we outline the emerging potential of combining wearable sensor monitoring with omics profiling to generate a comprehensive, dynamic evidence base.

Results: Evidence consistently shows that male puberty is associated with lasting increases in muscle mass, strength, speed, and endurance due to elevated testosterone. Current evidence also suggests such physiological adaptations may endure even after testosterone suppression, potentially mediated by muscle memory mechanisms such as myonuclei permeance and/or epigenetic changes. If verified, transgender women who experienced male puberty and later reduced testosterone levels retain physical advantages, particularly in strength-based sports. Similarly, athletes with DSD exhibiting male-range testosterone levels also show performance advantages in select events.

Conclusions: The IOC's principle of "No Presumption of Performance Advantage" contradicts a substantial body of scientific evidence. While inclusion and fairness are important goals, the framework's rejection of testosterone as a key determinant of athletic performance risks undermining competitive fairness and athlete safety in sex-segregated sports, particularly where strength and power are critical. Acknowledging testosterone as a key determinant of performance, our study proposes a novel multi-layered evaluation framework that integrates real-time sensor data with omics analyses. This innovative approach supports the development of adaptive, context-specific, and ethically grounded policies that promote fair, inclusive, and safe competition while offering a forward-looking roadmap for future policy and research.

Introduction: Physical inactivity is a global problem today, with multiple negative impacts on physical and psychological health. This study used the self-determination perspective and the hierarchical model of leisure constraints to study recreational sport participation within the framework of the leisure negotiation proposition.

Methods: Latent class analysis (LCA) was employed in order to cluster individuals according to their motivation level (intrinsic, extrinsic, and amotivation) and to compare the cluster groups' scores on intrapersonal, interpersonal, and structural constraints. The sample of the study included three hundred and eighteen (N = 318) individuals of the general population in Greece.

Results: Three distinct segments emerged from the latent class analysis, based on the motivation scores. The study revealed that the cluster with the highest intrinsic and extrinsic motivation scores had the lowest intrapersonal constraints scores, providing support for the important roles of intrinsic and extrinsic motivation in successful negotiation and overcoming intrapersonal constraints.

Conclusion: The role of extrinsic motivation should be noted, as it is equally important in the context of recreational sports, alongside intrinsic motivation, through the individual's internalization processes.

Introduction: This study investigated whether velocity-based resistance training provides additional benefits to lower limb performance compared to standard exercise execution.

Methods: Twenty untrained adult women (37-55 years) were randomly assigned to two resistance training groups to perform resistance training with three sets of four lower body exercises per week for 6 weeks. The number of repetitions and lifting velocity differed between the groups. One group performed lower body exercises with maximal intent and a 10% velocity loss threshold termination (VB10%; n = 10), while the other group performed 10 repetitions at a standard 1:2 s concentric:eccentric tempo (STD; n = 10). The number of repetitions was recorded during the sessions. Before and after the intervention, power, muscular endurance and dynamic stability of the lower limbs were assessed using the mean propulsive velocity (MPV) and power (MPP) at 70% one-repetition maximum in the squat and deadlift, the Y-balance test (YBT) and the 30-second sit-to-stand test (STS), respectively. A two-way analysis of variance was used to assess the effects of time, group, and their interaction.

Results: The difference between 10 repetitions in the STD and repetitions in the VB10% was assessed using a one-sample t-test. Both groups significantly improved MPP, MPV, YBT and STS [mean difference (MD) ≥5.4%; effect size (ES) ≥0.6]. Although 2.5-2.7 less repetitions were performed in VB10%, the improvements in MPP and MPV were slightly greater (ES ≥ 1.2 vs. ≥ 0.8). Conversely, STS and YBT improved more in STD (ES ≥ 0.4 vs. ≥ 1.0).

Discussion: Regardless of the lifting method used, the training intervention improved lower limb power, muscular endurance and dynamic stability, indicating that resistance training is an effective strategy for enhancing these capacities in untrained adult women. Using 10% threshold may be a more time-efficient strategy for improving lower-limb power in this population and could represent a promising approach for mitigating early declines in power over time.

Purpose: Ultra-endurance performance involves complex neuromuscular demands, yet continuous in-race assessment of strength and power development is lacking. This study examined the first-ever continuous profile of neuromuscular fatigue throughout an entire ultra-trail race to understand fatigue mechanisms and inform training and pacing strategies.

Methods: Fifty-five participants (43 men, 12 women; 45.2 ± 13.6 years) attempted six identical 26 km laps with 1,000 m elevation gain and loss per lap, 14 did not complete the course. Maximum knee-extensor and handgrip strength, peak-power output, and jump-height were measured pre-race, after each lap, and 12 h post-race using standardized protocols and linear mixed models.

Results: Knee-extensor strength decreased by ∼41% from pre-race to finish (p < .001), with substantial recovery (Δ26%-27%) at 12 h post-race. Handgrip strength showed minimal overall decline (Δ∼2%-5%), suggesting fatigue localized to the lower limbs. Peak-power and jump-height declined gradually (Δ6%-7% from early laps; p < .001). Critically, no significant relationship existed between the magnitude of strength loss and final ranking (early and late finishers showed no differences in strength profiles). However, participants who withdrew at lap 5 displayed substantially lower baseline strength (Δ27%; p = .004) and progressive strength declines compared to finishers, suggesting baseline neuromuscular capacity may influence completion likelihood.

Conclusion: Continuous in-race profiling reveals that ultra-trail running induces substantial and predominantly peripheral neuromuscular fatigue in the lower limbs, with limited systemic effects. While strength loss magnitude does not predict race placement among finishers, lower baseline strength may increase non-completion risk. These findings underscore the importance of targeted strength training and metabolite-clearance strategies (e.g., glycogen replenishment, hydration, recovery) in ultra-endurance preparation.