Search

BACKGROUND: Endurance training can have a negative impact on strength training and may lead to reduced strength gains, known as the interference effect. However, high-intensity interval training (HIIT) as an endurance training mode may reduce this interference effect. OBJECTIVE: This systematic review and meta-analysis aim to investigate the effects of concurrent HIIT and resistance training (RT) on lower body explosive strength and maximum strength. METHODS: Five electronic databases were searched. Subgroup analyses were performed to assess the effects of HIIT modality, training status, and training duration on strength development following concurrent HIIT and RT. RESULTS: Meta-analysis showed that compared to RT alone, concurrent HIIT and RT will not affect the development of countermovement jump (CMJ) (WMD = - 0.17, 95%CI = - 1.45 to - 1.11) and half squat (WMD = - 0.05, 95%CI = - 2.42 to 2.32). Further, subgroup analysis revealed that HIIT-running workout was conducive to the development of both CMJ and half squat. Longer training duration was found to be more effective in developing CMJ, while shorter training duration was more suitable for developing half squat. Additionally, athletes showed greater improvement than non-athletes. CONCLUSIONS: Combining HIIT and RT can enhance CMJ and half squat. The results of intervention are moderated by training variables and training status. [ABSTRACT FROM AUTHOR]

Based on fractal theory,continuous smooth exponential model of elastic-plastic contact,and considering the influence of friction factors and applying an improved W-M function that simulating three-dimensional fractal profile surface,the fractal model of energy dissipation for tangential contact in joint interfaces and its equivalent viscous damping model are proposed.It is shown from the models that the tangential contact damping dissipating energy of joint interfaces decreases with the increase of normal load on joint interfaces,the friction coefficient,but increases with the increase of plastic index of contact materials,the ratio of the tangential dynamic load amplitude to normal contact load,the fractal dimension,the fractal roughness of joint interfaces. The variation rule of the tangential contact damping dissipating energy of joint interfaces with the fractal dimension is very complex. The tangential equivalent viscous damping of joint interfaces decreases with the increase of friction coefficient,the fractal roughness of joint interfaces,but increases with the increase of normal load on joint interfaces,the ratio of the tangential dynamic load amplitude to normal contact load,the plastic index of contact materials. The tangential contact equivalent viscous damping of the joint surface increases at first and then decreases with the increase of the fractal dimension,and the maximum value is taken when the fractal dimension is equal to 2. 7. There is an obvious nonlinear relationship between the tangential contact equivalent viscous damping of joint interfaces,when fractal dimension D value is between 2. 1 and 2. 5. There is an obvious linear relationship between the tangential contact equivalent viscous damping of joint interfaces and the normal contact load,when fractal dimension D value is between 2. 5 and 2. 9.

This study aimed to separately compare and rank the effect of various living-low and training-high (LLTH) modes on aerobic and anaerobic performances in athletes, focusing on training intensity, modality, and volume, through network meta-analysis. We systematically searched PubMed, Web of Science, Embase, EBSCO, and Cochrane from their inception date to June 30, 2023. Based on the hypoxic training modality and the intensity and duration of work intervals, LLTH was divided into intermittent hypoxic exposure, continuous hypoxic training, repeated sprint training in hypoxia (RSH; work interval: 5–10 s and rest interval: approximately 30 s), interval sprint training in hypoxia (ISH; work interval: 15–30 s), short-duration high-intensity interval training (s-IHT; short work interval: 1–2 min), long-duration high-intensity interval training (l-IHT; long work interval: > 5 min), and continuous and interval training under hypoxia. A meta-analysis was conducted to determine the standardized mean differences (SMDs) among the effects of various hypoxic interventions on aerobic and anaerobic performances. From 2,072 originally identified titles, 56 studies were included in the analysis. The pooled data from 53 studies showed that only l-IHT (SMDs: 0.78 [95% credible interval; CrI, 0.52–1.05]) and RSH (SMDs: 0.30 [95% CrI, 0.10–0.50]) compared with normoxic training effectively improved athletes' aerobic performance. Furthermore, the pooled data from 29 studies revealed that active intermittent hypoxic training compared with normoxic training can effectively improve anaerobic performance, with SMDs ranging from 0.97 (95% CrI, 0.12–1.81) for l-IHT to 0.32 (95% CrI, 0.05–0.59) for RSH. When adopting a program for LLTH, sufficient duration and work intensity intervals are key to achieving optimal improvements in athletes' overall performance, regardless of the potential improvement in aerobic or anaerobic performance. Nevertheless, it is essential to acknowledge that this study incorporated merely one study on the improvement of anaerobic performance by l-IHT, undermining the credibility of the results. Accordingly, more related studies are needed in the future to provide evidence-based support. It seems difficult to achieve beneficial adaptive changes in performance with intermittent passive hypoxic exposure and continuous low-intensity hypoxic training. [ABSTRACT FROM AUTHOR]

Objectives: Hostile neck abdominal aortic aneurysm (AAA) is challenging for standard endovascular aneurysm repair (EVAR). We sought to compare fenestrated endovascular aneurysm repair (fEVAR) and chimney endovascular aneurysm repair (chEVAR) for hostile neck AAA. Methods: Patients were identified retrospectively. Hostile neck anatomy was defined as a proximal neck length of <15 mm or angulation >60°. The choice of fEVAR or chEVAR was based on neck anatomy and physician preference. Type I endoleak (T1EL) was the primary outcome. Other outcomes included type III endoleak (T3EL), visceral stent occlusion, renal insufficiency, reintervention, and mortality. Results: A total of 84 patients were included from April 2012 to December 2021. fEVAR and chEVAR patients were 48 and 36 cases, respectively. Both groups showed similar rate of T1EL, T3EL, visceral stent occlusion, renal insufficiency, reintervention, and mortality. However, chEVAR patients had a more tortuous neck (61.1% vs. 16.7%, p < 0.001), while fEVAR patients had a greater neck size (29.5 ± 6.3 mm vs. 24.5 ± 4.8 mm, p < 0.001) and more reconstructing target arteries (2.2 ± 1.1 vs 1.3 ± 0.6, p < 0.001). Conclusions: fEVAR and chEVAR show similar safe and effective outcomes in well-selected hostile neck. fEVAR might be able to reconstruct multiple visceral arteries, and chEVAR seems justified in patients with poor anatomical suitability for fEVAR. [ABSTRACT FROM AUTHOR]

This study aims to optimize the sustainable utilization of excavated soil by incorporating it exclusively as a fine aggregate and cement in the formulation of soil-based controlled low-strength materials. The polycarboxylate superplasticizer was introduced to enhance flowability. Various factors, including the cement contents, initial water contents, and curing time, were systematically analyzed for their effects on the fresh properties, mechanical parameters, transverse relaxation time distribution, pore size distribution, porosity, and corrosivity of soil-based controlled low-strength materials. The results indicate that polycarboxylate superplasticizer effectively dispersed clay minerals and cement particles, enhancing the flowability. The unconfined compressive strength increased with the rising cement content and decreased with the increasing initial water content. Additionally, the transverse relaxation time distribution curves of the soil-based controlled low-strength materials exhibited two peaks. These curves shifted to smaller transverse relaxation time values with the increasing cement content, while gradually shifting to larger transverse relaxation time values with the increasing initial water content. An increase in the cement content resulted in higher volume percentages of small and mesopores, while extra-large pores and macropores decreased. The addition of the polycarboxylate superplasticizer had minimal impact on the pore volume percentage distribution. Furthermore, porosity experienced a decline with the rise in the cement content and curing time, in contrast to a notable increase with a higher initial water content. This investigation provides valuable insights into the engineering properties and microstructural characteristics of soil-based controlled low-strength materials, offering a foundation for sustainable waste management practices in geotechnical applications. [ABSTRACT FROM AUTHOR]