Search Results (5)

Introduction: Monitoring training load is essential in elite soccer to optimize performance and reduce injury risk. The training-to-match load ratio (TMr) has emerged as a useful metric to contextualize training demands relative to competitive match exposure. The objective of this study was to compare daily and accumulated TMr between starters and non-starters over a professional season, considering microcycle day and playing position. Methods: Twenty players (Tier 3) from a professional team were monitored during a full competitive season (30 microcycles; 144 training sessions; 30 matches). External load variables, namely total distance (TD), high-speed distance (HSD), sprint distance (SPD), high metabolic load distance (HMLD), acceleration (ACC) and deceleration (DCC), were collected using 10 Hz GPS devices (STATSports). Daily and microcycle TMr were calculated relative to each player’s maximal match value registered during a full competitive period. Linear mixed-effects models examined the effects of starting status, microcycle day, and playing position. Results: Linear mixed models revealed significant three-way interactions (status × day × position) for locomotor variables: TD (F = 3.36, p < 0.001), HSD (F = 2.49, p < 0.001), and SPD (F = 3.37, p < 0.001). Starters accumulated higher loads on match day, whereas non-starters showed higher TMr on MD + 1 and MD + 2. Position-specific differences emerged during acquisition sessions (i.e., MD − 5 to MD − 3), particularly for wide midfielders (WMs) and central defenders (CDs). No significant three-way interactions were observed for ACC, DCC, or HMLD absolute loads (p > 0.05), nor for any accumulated microcycle TMr metrics (p > 0.05). Conclusions: TMr effectively differentiates preparation strategies between starters and non-starters. Although “top-up conditioning” sessions increase early-week relative loads for non-starters, position-specific variations–particularly in mechanical variables during acquisition sessions–highlight the need for individualized load prescription. Full article

Background: Carbon dioxide (CO₂) is traditionally regarded as a metabolic by-product; however, growing evidence indicates that it plays an active regulatory role across multiple physiological systems. Acute hypercapnia elicits respiratory, cardiovascular, metabolic, immune, and neurocognitive responses, some of which may transiently influence exercise performance. This narrative review summarizes current evidence on CO₂ inhalation in healthy individuals and critically evaluates whether controlled hypercapnia may serve as a targeted stimulus in sport and exercise contexts. Methods: A narrative review of peer-reviewed English-language articles indexed in PubMed and Web of Science was conducted. A narrative approach was chosen due to the marked heterogeneity of study designs, hypercapnia-induction methods (e.g., CO₂ inhalation, voluntary hypoventilation, increased respiratory dead space), participant characteristics, and outcome measures, which precluded systematic synthesis. The review focused on studies involving healthy or physically active individuals and examined acute or short-term hypercapnic exposure. No strict publication date limits were applied. Studies conducted exclusively in clinical populations were excluded. Results: Short-term, controlled hypercapnia reliably increases ventilation, sympathetic activation, cerebral and muscular blood flow, and metabolic stress. Certain hypercapnia-based interventions—such as voluntary hypoventilation or added respiratory dead space—may enhance buffering capacity, reduce lactate accumulation and improve maximal oxygen uptake (VO₂max) during submaximal efforts and repeated-sprint performance during high-intensity, short-duration exercise. However, CO₂ inhalation frequently induces dyspnea, anxiety, and cognitive disruption, and higher concentrations pose clear safety risks. Current evidence does not support long-term improvements in VO₂max or long-duration endurance performance following hypercapnia-based interventions. Conclusions: Controlled, intermittent hypercapnia may provide a targeted metabolic and ventilatory stimulus that enhances tolerance to high-intensity exercise, yet its application remains experimental and context-dependent. The risks associated with CO₂ inhalation in healthy individuals currently outweigh its potential benefits, and safe, effective training protocols have not been fully established. Further research is needed to clarify the mechanisms, long-term adaptations, and practical utility of hypercapnia-based training strategies. Full article

Background: Hamstring strain injuries (HSIs) are among the most common and recurrent injuries in sports involving high-speed running. While eccentric training has demonstrated efficacy in reducing HSI risk, the role of sprint training as a preventive strategy remains underexplored and often misinterpreted as solely a risk factor. Methods: This review aimed to systematically map the available evidence on the role of sprint training in hamstring injury prevention, identifying mechanisms, outcomes, and potential synergies with other strategies. This scoping review was conducted following the Joanna Briggs Institute’s methodology and reported in accordance with PRISMA-ScR guidelines. Seven databases (PubMed, Scopus, Web of Science, Cochrane CENTRAL, SPORTDiscus, CINAHL, and PEDro) were searched up to October 2024. Studies were included if they involved adult athletes and examined the effects of sprint training, ≥80–90% maximal sprint speed (MSS), on hamstring injury prevention, muscle architecture, or functional outcomes. All databases were searched from inception to 15 October 2024, and the screening and data-charting process was completed on 30 April 2025. Results: Twelve studies met the inclusion criteria. Sprint exposure, when combined with eccentric strengthening and biomechanical optimisation, led to injury reductions ranging from 56% to 94%. Eccentric interventions produced fascicle length increases of up to 20% and strength gains of 15–20%. Improvements in sprint technique and neuromuscular control were also reported. Biomechanical risk factors, including pelvic tilt and hip extension deficits, were linked to increased HSI risk. The most common eccentric protocols included Nordic Hamstring Exercises (NHE), Razor Curls, and hip-dominant exercises, typically performed 1–2 times per week for 4 to 8 weeks. Conclusions: High-speed sprint training, when properly programmed and integrated into comprehensive preventive strategies, may enhance tissue resilience and reduce HSI risk. Combining sprint exposure with eccentric strengthening and technical coaching appears to be more effective than isolated interventions alone. Practically, these results support the systematic inclusion of progressive high-intensity sprint exposure in routine hamstring-injury-prevention programmes for field-sport athletes. Full article

Background: Hamstring strains are the most common moderate-major severity injuries in football. The majority of hamstring injuries occur during sprinting, with low eccentric hamstring strength being associated with an elevated risk. Objective: To examine the relationship between sprinting and eccentric hamstring strength by monitoring total weekly sprint distance and weekly efforts > 90% and >95% of maximum velocity. Methods: Fifty-eight professional male footballers were observed over one-and-a-half seasons. Players’ running was monitored during training and matches using GPS, and eccentric hamstring strength was measured weekly. Results: Weekly sprint distance (ρ = −0.13, p < 0.01) and weekly efforts >90% of maximum velocity (ρ = −0.08, p = 0.01) both displayed significant inverse relationships with the percentage change in eccentric hamstring strength; weekly efforts >95% of maximum velocity showed no relationship with hamstring strength (ρ = −0.02, p = 0.45). Only weekly efforts >90% of maximum velocity significantly influenced the mean percentage change in eccentric hamstring force, F_(3,58) = 3.71, p = 0.01, with significant differences occurring when comparing 7–8 sprint efforts with 0–2 efforts (0.11%, p = 0.03) and 5–6 efforts (0.12%, p = 0.03). Conclusions: Eccentric hamstring strength levels significantly decrease when 7–8 weekly sprint efforts are completed at >90% of maximum velocity. Monitoring weekly sprint loading at velocities > 90% of maximum velocity may be valuable to help to reduce the risk of hamstring injuries in professional football. Full article

Purpose: (1) To determine the contribution of diet, time spent outdoors, and habitual physical activity (PA) on vitamin D status in men with cerebral palsy (CP) compared to physical activity matched controls (TDC) without neurological impairment; (2) to determine the role of vitamin D on musculoskeletal health, morphology, and function in men with CP compared to TDC. Materials and methods: A cross-sectional comparison study where 24 active, ambulant men with CP aged 21.0 ± 1.4 years (Gross Motor Function Classification Score (I–II) and 24 healthy TDC aged 25.3 ± 3.1 years completed in vivo assessment of musculoskeletal health, including: vastus lateralis anatomical cross-sectional area (VL ACSA), isometric knee extension maximal voluntary contraction (KE iMVC), 10 m sprint, vertical jumps (VJ), and radius and tibia bone ultrasound (US) T_us and Z_us scores. Assessments of vitamin D status through venous samples of serum 25-hydroxyvitamin D (25(OH)D) and parathyroid hormone, dietary vitamin D intake from food diary, and total sun exposure via questionnaire were also taken. Results: Men with CP had 40.5% weaker KE iMVC, 23.7% smaller VL ACSA, 22.2% lower VJ, 14.6% lower KE iMVC/VL ACSA ratio, 22.4% lower KE iMVC/body mass (BM) ratio, and 25.1% lower KE iMVC/lean body mass (LBM) ratio (all p < 0.05). Radius T_us and Z_us scores were 1.75 and 1.57 standard deviations lower than TDC, respectively (p < 0.05), whereas neither tibia T_us nor Z_us scores showed any difference compared to TDC (p > 0.05). The 25(OH)D was not different between groups, and 90.9% of men with CP and 91.7% of TDC had low 25(OH)D levels when compared to current UK recommendations. The 25(OH)D was positively associated with KE iMVC/LBM ratio in men with CP (r = 0.500, p = 0.020) but not in TDC (r = 0.281, p = 0.104). Conclusion: Musculoskeletal outcomes in men with CP were lower than TDC, and despite there being no difference in levels of 25(OH)D between the groups, 25 (OH)D was associated with strength (KE iMVC/LBM) in the CP group but not TDC. The findings suggest that vitamin D deficiency can accentuate some of the condition-specific impairments to musculoskeletal outcomes. Full article