Flywheel resistance training devices (FRTD) is shown effective in improving strength, sprinting, jumping and changes of direction (COD) performance in male soccer players, however, this is not elucidated in female soccer players. We aimed to assess the effect of FRTD on these physical abilities...

Background: The main aim of this study was (1) to find an index to monitor the loading intensity of flywheel resistance training, and (2) to study the differences in the relative intensity workload spectrum between the FW-load and ISO-load. Methods: twenty-one males participated in the study. Subjects executed an incremental loading test in the squat exercise using a Smith machine (ISO-load) or a flywheel device (FW-load). We studied different association models between speed, power, acceleration, and force, and each moment of inertia was used to find an index for FW-load. In addition, we tested the differences between relative workloads among load conditions using a two-way repeated-measures test. Results: the highest r2 was observed using a logarithmic fitting model between the mean angular acceleration and moment of inertia. The intersection with the x-axis resulted in an index (maximum flywheel load, MFL) that represents a theoretical individual maximal load that can be used. The ISO-load showed greater speed, acceleration, and power outcomes at any relative workload (%MFL vs. % maximum repetition). However, from 45% of the relative workload, FW-load showed higher vertical forces. Conclusions: MFL can be easily computed using a logarithmic model between the mean angular acceleration and moment of inertia to characterize the maximum theoretical loading intensity in the flywheel squat.

Objective: The objective was to systematically identify and categorize return-to-play (RTP) domains and criteria used following muscle injuries in male soccer players, and to describe the certainty of the evidence according to the number, design and methodological quality of the studies implementing RTP criteria within each domain. Methods: In total, six databases were searched up to 10 March 2024. Studies reporting RTP criteria for hamstring, adductor, quadriceps, and calf injuries, as well as general criteria for all muscle injuries, were included. The certainty of evidence for RTP criteria was assessed on the basis of the studies citing each criterion. Results: Out of 58,057 records, 135 studies met the inclusion criteria. Strength and pain criteria are the most cited tests for determining RTP clearance following hamstring injuries, particularly criteria related to between-limb knee flexors/extensors strength symmetry and no pain during soccer-specific actions. Range of motion criteria (active knee extension, passive and active straight leg raise, and Askling-H tests) and subjective readiness demonstrated the highest certainty of evidence in RTP decision making after hamstring injuries. RTP criteria following adductor injuries showed a moderate-to-very-low certainty of evidence across domains. Criteria for quadriceps and calf injuries ranged from low to very low evidence, while general lower limb muscle injury criteria had only very low evidence. Following adductor injuries, the highest evidence (moderate) was shown by pain assessments and completing at least one full team training session. Conclusions: Symmetry between limbs in knee flexor and extensor strength combined with no pain during soccer-specific actions were the most frequently implemented RTP criteria for hamstring injuries. In addition, range of motion evaluation (i.e., active knee extension, passive and active straight leg raise, and Askling- H tests) and subjective readiness assessments have been more consistently employed in higher-quality intervention studies than other domains following hamstring injuries in soccer players. Pain assessments, completing at least one full team training session and restoring strength levels are the most cited criteria for RTP following adductor injuries. The evidence base describing RTP criteria for quadriceps and calf injuries is limited and is not implemented in randomized controlled trials with high methodological quality, highlighting the need for further robust research in these domains. Trial Registration Number: PROSPERO CRD42022363836.

To review the effectiveness of isokinetic training as an alternative method to traditional isotonic resistance training. Researchers examined data from PubMed, CENTRAL, MEDLINE COMPLETE, and Web of Science until February 2023. A total of 365 entries were obtained from databases, including studies that analyzed the effects of isokinetic vs. isotonic-based rehabilitation in athletes (16-50 years) after a surgical knee intervention. Return to sport (RTS), strength of the flex/extensor compartment of the thigh, muscle mass of the thigh, and knee function were screened as main outcomes. Two reviewers independently screened the studies for eligibility and assessed risk of bias of the included ones. Six studies involving 181 athletes were included. Isokinetic training demonstrated significant benefits in peak torque for knee flexor-extensor muscles in four studies. Two studies favored isokinetic training over isotonic for strength. Muscle mass findings were mixed, with one study favoring isokinetic significantly and two showing no significant differences. In terms of returning to sport, the isotonic group displayed slightly better limb symmetry index values, but without significance. Isokinetic training outperformed isotonic in two functionality questionnaire studies, while two others showed no significant differences. Isokinetic training appears equally, if not more effective than isotonic, for restoring strength balance between hamstrings and quadriceps. This could lead to more favorable muscle mass changes. Isokinetic training also parallels isotonic rehabilitation for functional outcomes and meeting return-to-sport criteria. Therefore, isokinetic training should be included as one of the main strength restoration strategies after knee surgery, especially in early and middle rehabilitation stages.

Competitive swimmers have a high prevalence of sports supplement (SS) consumption. However, only a few SS are scientifically proven to be safe, effective, and legal. Therefore, before incorporating supplements to enhance performance and health in competitive swimming, it is crucial to conduct an analysis and review to assess their effects. The objective of this study was to analyze the demonstrated effects of SS, as reported in published studies, on the swimming performance of competitive swimmers. Following PRISMA guidelines, a systematic search was conducted across six databases for the selection of studies included in this review. Studies that analyzed the effects of sports supplementation compared to placebo were included and subjected to meta-analysis. This revision included 23 studies, 16 of them (69.6%) qualified as excellent and 7 (30.4%) as good at the methodological level based on the punctuation in the PEDro scale. The systematic review included 422 swimmers (61.8% male, 38.2% female), with distances assessed ranging from 50 m to 800 m, including studies employing interval procedures. Creatine showed a significant effect (ES = -0.46; 95% CIs = -0.75 to -0.17, p = 0.002; I² = 11%) on swimming performance, while the rest of the analyzed supplements did not show significant effects (all p > 0.05). Creatine supplementation demonstrated ergogenic benefits for competitive swimmers, although the evidence supporting the use of this supplement is still limited. Sodium bicarbonate and β-alanine may enhance performance in distances with higher glycolytic demands, while caffeine is effective at dosages of 3-6 mg/kg administered 60 min before exercise. Further research is needed to confirm the potential ergogenic effects of other supplements, such as beetroot juice.

This systematic review and meta-analysis examined the effects of analogy instruction (ANA) on motor performance and knowledge declared (KD) compared with explicit learning (EXP) and control conditions. Five databases were included. The study analyzed 16 randomized controlled trials. Subsequent analysis was performed for moderators variables as age, skill, retention, stress situations number of rules, specificity and number of trials. The ANA instruction demonstrated greater efficacy than the control (ES = 0.32, p = 0.03) or EXP condition (ES = 0.29, p = 0.02) in motor tasks performance in general terms. ANA instructions also showed superiority in motor performance when compared to control conditions in retention (ES = 5.72, p = 0.004), and a trend towards significance was found under stress (ES = 1.18, p = 0.05). ANA also showed superiority in motor performance when compared to EXP instruction (ES = 0.29, p = 0.02). ANA demonstrated greater effects than EXP in retention (ES = 7.25, p = 0.01), but not under stress (ES = 0.62, p = 0.18). Sub-analyses demonstrated that children (all p < 0.01) and novices (all p < 0.01) are more likely to benefit from ANA instruction when compared to control or EXP. A subgroup analysis based on quantity of information comparing ANA versus EXP condition shows that ANA is more effective for enhancing motor performance than EXP when the number of rules are similar. Sub-analyses comparing ANA versus CNT shows that as the number of repetitions increases and the task becomes less specific, ANA instruction significantly improves performance. A comparison between ANA and EXP indicates no significant differences in performance regarding the number of repetitions and task specificity. A secondary analysis examined KD of different instructions. KD was greater in EXP instructions (ES = -1.48, p < 0.001) when compared to ANA. Findings suggest that analogy instruction may improve motor performance, especially in novice and child populations. However, caution is needed due to concerns when comparing with other instructional types and environments, as well as due to high heterogeneity in most of the comparisons and high risk of bias in included studies.