This study compared the velocity- and power-load relationships of the antagonistic upper-body exercises of prone bench pull (PBP) and bench press (BP). 75 resistance-trained athletes performed a ...progressive loading test in each exercise up to the one-repetition maximum (1RM) in random order. Velocity and power output across the 30-100% 1RM were significantly higher for PBP, whereas 1RM strength was greater for BP. A very close relationship was observed between relative load and mean propulsive velocity for both BP (R2=0.97) and PBP (R2=0.94) which enables us to estimate %1RM from velocity using the obtained prediction equations. Important differences in the load that maximizes power output (Pmax) and the power profiles of both exercises were found according to the outcome variable used: mean (MP), peak (PP) or mean propulsive power (MPP). When MP was considered, the Pmax load was higher (56% BP, 70% PBP) than when PP (37% BP, 41% PBP) or MPP (37% BP, 46% PBP) were used. For each variable there was a broad range of loads at which power output was not significantly different. The differing velocity- and power-load relationships between PBP and BP seem attributable to the distinct muscle architecture and moment arm levers involved in these exercises.
Evidence supports the fact that multicomponent exercise and HMB supplementation are, separately, effective in improving older adult's health and palliate functional metabolic diseases in older ...people. However, the true effect of HMB supplementation combined with a tailored exercise program in frail older adults is still unknown. Thus, the aim of the HEAL (HMB + Exercise = Adults Living longer) study is to assess the effects of the combination of a daily multicomponent exercise and resistance training (VIVIFRAIL program) intervention in addition to HMB supplementation on older adults' health.
A 24-week cluster randomized, double-blind, placebo-controlled study will be conducted on 104 adults ≥70 years. Nursing homes will be randomized to either of four groups: Ex-HMB (exercise intervention with HMB), Ex-Plac (exercise intervention with placebo), NoEx-HMB (no exercise intervention with HMB), and Controls (No exercise and no HMB). Intervention groups which include exercise will complete the individualized multicomponent (strength, balance and cardiovascular exercises) training program VIVIFRAIL. Intervention groups which include HMB supplementation will receive a 3 g/daily dose of free acid HMB in powder form. The primary outcome measure is the functional capacity. Secondary outcome measures are muscle strength and power, frailty and fall risk, body composition, biochemical analyses and cardiometabolic risk factor, disability and comorbidity, cognitive function and depression.
The findings of the HEAL study will help professionals from public health systems to identify cost-effective and innovative actions to improve older people's health and quality of life, and endorse exercise practice in older adults and people living in nursing homes.
NCT03827499 ; Date of registration: 01/02/2019.
This study compared the effects of concentric and eccentric training on neuromuscular adaptations in young subjects. Twenty‐two men and women were assigned to one of two groups: concentric (CON, n = ...11) and eccentric (ECC, n = 11) training. Training consisted of 6 weeks of isokinetic exercise, performed twice weekly, starting with two sets of eight repetitions, and progressing to five sets of 10 repetitions. Subjects were tested in strength variables concentric, eccentric, and isometric peak torque (PT), and rate of force development (RFD), muscle conduction velocity (CV), neuromuscular activity, vastus lateralis (VL) muscle thickness, and echo intensity as determined by ultrasonography. There were similar increases in the concentric and eccentric PTs in both the CON and ECC groups (P < 0.01), but only the ECC group showed an increase in isometric PT (P < 0.001). Similarly, both groups exhibited increased VL muscle thickness, CV, and RFD, and reduced VL echo intensity (P < 0.05). Significant correlations were observed among the relative changes in the neuromuscular outcomes and training variables (e.g., total work, average PT) (r = 0.68–0.75, P < 0.05). The results showed that both training types similarly improved dynamic PT, CV, RFD, and muscle thickness and quality during the early weeks of training.
•Twenty experimental tests carried out on full-scale interior beam-column joints.•Five strengthening techniques tested to retrofit existing beam-column joints underdesigned to seismic actions.•Steel ...jacketing technique is studied as a seismic strengthening.•Test set up defined to apply both gravity and cyclic loads combination on beams.•Results are shown about ductility and strength enhancement achieved in the specimens.
This paper presents an experimental program designed to determine the behaviour of steel jacketing used as a seismic strengthening system for reinforced concrete frame structures. Tests were carried out on a total of 20 full scale interior beam-column joints. Geometry and reinforcements were selected according to existing buildings, designed solely to gravity loads under strong beam-weak column concept. Column strengthening was performed in all specimens, and four different types of column-joint connection strengthening have been tested. Two types of beam reinforcement have been included in the experimental program. Tests were carried out by subjecting specimens to gravity and cyclic loads. The paper shows general results and conclusions, describing the failure modes of the specimens. Results show that the strengthening techniques and the axial loads applied on columns can have significant influence on the seismic behaviour of the joints.
This study investigated which exercise mode (continuous or sprint interval) is more effective for improving insulin sensitivity. Ten young, healthy men underwent a non-exercise trial (CON) and 3 ...exercise trials in a cross-over, randomized design that included 1 sprint interval exercise trial (SIE; 4 all-out 30-s sprints) and 2 continuous exercise trials at 46% VO2peak (CELOW) and 77% VO2peak (CEHIGH). Insulin sensitivity was assessed using intravenous glucose tolerance test (IVGTT) 30 min, 24 h and 48 h post-exercise. Energy expenditure was measured during exercise. Glycogen in vastus lateralis was measured once in a resting condition (CON) and immediately post-exercise in all trials. Plasma lipids were measured before each IVGTT. Only after CEHIGH did muscle glycogen concentration fall below CON (P<0.01). All exercise treatments improved insulin sensitivity compared with CON, and this effect persisted for 48-h. However, 30-min post-exercise, insulin sensitivity was higher in SIE than in CELOW and CEHIGH (11.5±4.6, 8.6±5.4, and 8.1±2.9 respectively; P<0.05). Insulin sensitivity did not correlate with energy expenditure, glycogen content, or plasma fatty acids concentration (P>0.05). After a single exercise bout, SIE acutely improves insulin sensitivity above continuous exercise. The higher post-exercise hyperinsulinemia and the inhibition of lipolysis could be behind the marked insulin sensitivity improvement after SIE.
This study analyzed the effects of pseudoephedrine (PSE) provided at different time of day on neuromuscular performance, side effects, and violation of the current doping cut‐off threshold World ...Anti‐Doping Agency (WADA). Nine resistance‐trained males carried out bench press and full squat exercises against four incremental loads (25%, 50%, 75%, and 90% one repetition maximum 1RM), in a randomized, double‐blind, cross‐over design. Participants ingested either 180 mg of PSE (supra‐therapeutic dose) or placebo in the morning (7:00 h; AMPLAC and AMPSE) and in the afternoon (17:00 h; PMPLAC and PMPSE). PSE enhanced muscle contraction velocity against 25% and 50% 1RM loads, only when it was ingested in the mornings, and only in the full squat exercise (4.4–8.7%; P < 0.05). PSE ingestion raised urine and plasma PSE concentrations (P < 0.05) regardless of time of day; however, cathine only increased in the urine samples. PSE ingestion resulted in positive tests occurring in 11% of samples, and it rose some adverse side effects such us tachycardia and heart palpitations. Ingestion of a single dose of 180 mg of PSE results in enhanced lower body muscle contraction velocity against low and moderate loads only in the mornings. These mild performance improvements are accompanied by undesirable side effects and an 11% risk of surpassing the doping threshold.
This study determined the effects of a 4-week individualized multicomponent exercise program (Vivifrail) on physical frailty and functional disability in older adults living in nursing homes. ...Fourteen institutionalized older adults (aged 81.7 ± 9.7 years) volunteered to completed 4 weeks of the individualized Vivifrail exercise program (5 days a week) according to their initial level: A, disability; B, frailty; C, pre-frailty and D, robust. Training sessions were directed by strength and conditioning trainers. Eleven participants completed the pre and post evaluations with very high levels of attendance (96% of the training sessions). Functional capacity (SPPB scores) significantly improved in all the participants (+48.2%,p < 0.001) and tests: sit-to-stand (24.1% faster, p = 0.003), gait speed 4 m (9.8% faster, p = 0.033) and 6 m (7.2% faster, p = 0.017) and Up and Go (11.2% faster, p = 0.004). Disability and sarcopenia decreased significantly (SARC-F, p = 0.026; Lawton index, p = 0.013). People with initial levels of disability (A), frailty (B) and pre-fragility (C) shown the greatest improvements. Six of the nine participants who started with physical frailty or pre-frailty status (66.7%) reversed this condition after the intervention. In addition, 33% of participants with disability, who were unable to perform the functional tests (sit-stand and walk), became able to complete them after the intervention. These important benefits found in such a shorter period of time (4 weeks) could be related to three key elements: individualization of the program, daily frequency and face-to-face coaching motivation by physical conditioning professionals.
It is habitual for combat sports athletes to lose weight rapidly to get into a lower weight class. Fluid restriction, dehydration by sweating (sauna or exercise) and the use of diuretics are among ...the most recurrent means of weight cutting. Although it is difficult to dissuade athletes from this practice due to the possible negative effect of severe dehydration on their health, athletes may be receptive to avoid weight cutting if there is evidence that it could affect their muscle performance. Therefore, the purpose of the present study was to investigate if hypohydration, to reach a weight category, affects neuromuscular performance and combat sports competition results.
We tested 163 (124 men and 39 woman) combat sports athletes during the 2013 senior Spanish National Championships. Body mass and urine osmolality (UOSM) were measured at the official weigh-in (PRE) and 13-18 h later, right before competing (POST). Athletes were divided according to their USOM at PRE in euhydrated (EUH; UOSM 250-700 mOsm · kgH2O(-1)), hypohydrated (HYP; UOSM 701-1080 mOsm · kgH2O(-1)) and severely hypohydrated (S-HYP; UOSM 1081-1500 mOsm · kgH2O(-1)). Athletes' muscle strength, power output and contraction velocity were measured in upper (bench press and grip) and lower body (countermovement jump - CMJ) muscle actions at PRE and POST time-points.
At weigh-in 84 % of the participants were hypohydrated. Before competition (POST) UOSM in S-HYP and HYP decreased but did not reach euhydration levels. However, this partial rehydration increased bench press contraction velocity (2.8-7.3 %; p < 0.05) and CMJ power (2.8 %; p < 0.05) in S-HYP. Sixty-three percent of the participants competed with a body mass above their previous day's weight category and 70 of them (69 % of that sample) obtained a medal.
Hypohydration is highly prevalent among combat sports athletes at weigh-in and not fully reversed in the 13-18 h from weigh-in to competition. Nonetheless, partial rehydration recovers upper and lower body neuromuscular performance in the severely hypohydrated participants. Our data suggest that the advantage of competing in a lower weight category could compensate the declines in neuromuscular performance at the onset of competition, since 69 % of medal winners underwent marked hypohydration.
Post-COVID-19 Syndrome and the Potential Benefits of Exercise Jimeno-Almazán, Amaya; Pallarés, Jesús G.; Buendía-Romero, Ángel ...
International journal of environmental research and public health,
05/2021, Letnik:
18, Številka:
10
Journal Article
Recenzirano
Odprti dostop
The coronavirus disease (COVID-19), caused by severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) infection, is leading to unknown and unusual health conditions that are challenging to ...manage. Post-COVID-19 syndrome is one of those challenges, having become increasingly common as the pandemic evolves. The latest estimates suggest that 10 to 20% of the SARS-CoV-2 patients who undergo an acute symptomatic phase are experiencing effects of the disease beyond 12 weeks after diagnosis. Although research is beginning to examine this new condition, there are still serious concerns about the diagnostic identification, which limits the best therapeutic approach. Exercise programs and physical activity levels are well-known modulators of the clinical manifestations and prognosis in many chronic diseases. This narrative review summarizes the up-to-date evidence on post-COVID-19 syndrome to contribute to a better knowledge of the disease and explains how regular exercise may improve many of these symptoms and could reduce the long-term effects of COVID-19.
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•Inverted BHJ solar cells based on PTB7:PC70BM using TiOx as ETL with high efficiency and long-term stability.•TiOx improves efficiency and provides higher stability to iPSCs.•ISOS-D1 ...protocols was applied for degradation analysis of encapsulated and non-encapsulated TiOx-iPSCs.•Degradation of contacts interface is the main limiting of the devices lifetime.
In this study, we report bulk heterojunction inverted polymer solar cells (iPSCs) with high efficiency and long-term stability. The devices were fabricated on the basis of Thieno3,4bthiophene-alt-benzodithiophene (PTB7) and 6,6-phenyl C71 butyric acid methyl ester (PC70BM). An ultra-thin film of titanium oxide (TiOx) was used as electron transport layer (ETL). The effects of TiOx on the performance parameters and stability of iPSCs were compared to the effects on conventional PSCs and iPSCs using poly (9,9-bis(3′-(N,N-dimethylamino)propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene) (PFN) as ETL. The power conversion efficiency (PCE) of TiOx-iPSCs was 5% and 11% higher than that of PFN-iPSCs and conventional PSCs, respectively. In this study the time the PCE takes to reduce to 80% is hereafter referred to as the cell’s lifetime. In nitrogen, the lifetime of 6048h of TiOx-iPSCs was found to be five times longer than that of conventional PCE (1200h) and PFN-iPSC (1300h) cells. The main objective of this study was to consider ambient conditions in the dark as a more realistic exposure scenario for non-encapsulated TiOx-iPSCs. Under these conditions, the lifetime was found to be of several hours. This reduction was significantly faster than under nitrogen and can be attributed to the degradation of the contact interfaces driven by ambient oxygen and water. Electron mobility was also reduced by 75% within 24h. An additional encapsulation served to stabilize the TiOx-iPSCs under ambient conditions and lifetime was extended by up to 120h with no observed loss in electron mobility. Impedance spectroscopy was used to investigate the degradation causes of active layer and electrodes interlayers.
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