The application of the Shuttle Walking Test (SWT) to assess cardiorespiratory fitness and the intensity of this test in healthy participants has rarely been studied. This study aimed to assess and ...correlate the cardiorespiratory responses of the SWT with the cardiopulmonary exercise testing (CEPT) and to develop a regression equation for the prediction of peak oxygen uptake (VO2 peak) in healthy sedentary adult men.
In the first stage of this study, 12 participants underwent the SWT and the CEPT on a treadmill. In the second stage, 53 participants underwent the SWT twice. In both phases, the VO2 peak, respiratory exchange ratio (R), and heart rate (HR) were evaluated.
Similar results in VO2 peak (P>0.05), R peak (P>0.05) and predicted maximum HR (P>0.05) were obtained between the SWT and CEPT. Both tests showed strong and significant correlations of VO2 peak (r = 0.704, P = 0.01) and R peak (r = 0.737, P<0.01), as well as the agreement of these measurements by Bland-Altman analysis. Body mass index and gait speed were the variables that explained 40.6% (R2 = 0.406, P = 0.001) of the variance in VO2 peak. The results obtained by the equation were compared with the values obtained by the gas analyzer and no significant difference between them (P>0.05) was found.
The SWT produced maximal cardiorespiratory responses comparable to the CEPT, and the developed equation showed viability for the prediction of VO2 peak in healthy sedentary men.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract The influence of the knee flexion on muscle activation and transmissibility during whole body vibration is controversially discussed in the literature. In this study, 34 individuals had ...electromyography activity (EMG) of the vastus lateralis and the acceleration assessed while squatting with 60° and 90° of knee flexion either with or without whole-body vibration (WBV). The conditions were maintained for 10 s with 1 min of rest between each condition. The main findings were (1) the larger the angle of knee flexion (90° vs. 60°), the greater the EMG ( p < 0.001), with no difference on acceleration transmissibility; (2) for both angles of knee flexion, the addition of WBV produced no significant difference in EMG and higher acceleration compared to without WBV ( p < 0.001). These results suggest that the larger the knee flexion angle (60° vs. 90°), the greater the muscle activation without acceleration modification. However, the addition of WBV increases the transmissibility of acceleration in the lower limbs without modification in EMG of vastus lateralis.
ABSTRACTAvelar, NCP, Costa, SJ, da Fonseca, SF, Tossige-Gomes, R, Gripp, FJ, Coimbra, CC, and Lacerda, ACR. The effects of passive warm-up vs. whole-body vibration on high-intensity performance ...during sprint cycle exercise. J Strength Cond Res 26(11)2997–3003, 2012—The purpose of this study was to compare the effects of passive warm-up (PW), whole-body vibration (WBV), and control (C) on high-intensity performance during sprint cycle exercise. Six recreationally trained men performed a 30-second sprint cycle test after the 3 aforementioned conditions; each test was carried out on a different day after balanced-order experimental tests. The WBV consisted of 5 minutes of squats associated with WBV (45 Hz, 2 mm). The PW consisted of 30 minutes of PW using a thermal blanket on the thighs and legs (35 W). The C consisted of 30 minutes of no warm-up with the subject lying down. Motor neuron excitability from the vastus lateralis muscle, evaluated by electromyography (EMG), was determined before exercise at rest and during sprint cycle exercise. Blood lactate levels (BLs), evaluated by spectroscopy, and muscle temperature (MT) of the thigh, estimated indirectly by measuring skin temperature, were determined at following time pointsbefore exercise at rest (before and after experimental conditions), immediately, and 3 minutes after the 30-second sprint cycle test. Peak power, relative power, relative work, time of peak power, and pedaling cadence were significantly higher in the WBV compared with that for C (p < 0.05). Although MT was significantly greater in PW compared with that in WBV and C before exercise (p < 0.01), no significant differences were observed between the experimental conditions for BL immediately after sprint cycle exercise (p = 0.35) and in EMG during sprint cycle exercise (p = 0.16). Thus, it is plausible to suggest WBV as a method for an acute increase in high-intensity performance during sprint cycle exercise for athletes immediately before competition or training.
Knee osteoarthritis is a common disease in the elderly population worldwide. The alleviation of the symptoms associated with this disease can be achieved with physical exercise that induces a cascade ...of molecular and cellular processes. Of the neurotrophins, brain-derived neurotrophic factor (BDNF) appears to be the most affected by physical activity. Moreover, BDNF seems to have a negative modulatory role in inflammation, and its production by skeletal muscle cells or by cells of the immune system drives the immunoprotective role of physical activity in situations of chronic inflammation. Therefore, the aim of this study was to evaluate plasma BDNF concentrations in elderly individuals presenting with knee osteoarthritis. To accomplish this, sixteen volunteers (mean age 67 ± 4.41 years) presenting with clinically and radiographically diagnosed knee osteoarthritis were evaluated during acute exercise (1 session of 20 min on a treadmill) and after chronic exercise (12 weeks of aerobic training, consisting of a 50-min walk 3 times per week). Additionally, both a functional assessment (during a 6-min walk) and a pain perception assessment were performed at the start and at the end of physical exercises (training). The plasma BDNF concentrations were measured by ELISA. For the population studied, acute exercise increased the levels of BDNF only before the 12-week training period (
p
< 0.001). Moreover, the training augmented the plasma concentrations of BDNF (
p
< 0.0001) and improved clinical parameters (functional
p
< 0.001; pain perception
p
< 0.01).
This study aimed to investigate the efficacy of whole-body vibration training (WBVT) on blood brain-derived neurotrophic factor (BDNF) levels and determine the clinical and functional outcomes in ...patients with fibromyalgia syndrome (FMS). Thirty-two women with FMS were randomized into an intervention group (IG), receiving 6 weeks of WBVT, or a control group (CG) with no intervention. The outcomes at the baseline and follow-up in both groups included blood BDNF levels, sit-to-stand test (STS), 6-minute walk test (6MWT), Fibromyalgia Impact Questionnaire (FIQ), Pittsburgh Sleep Quality Index (PSQI), Beck Depression Inventory (BDI), and visual analogue scale (VAS). WBVT resulted in a group-by-time interaction effect. Thus, after the intervention time, the IG had increased blood BDNF levels (p=0.045), a higher number of repetitions on the STS test (p=0.011), and increased walking distance on the 6MWT (p=0.010), compared to CG. Moreover, there was a reduction in the scores of the FIQ (p=0.001), the PSQI (p=0.001), the BDI (p=0.017), and pain assessed using VAS (p=0.008) in IG. The results demonstrate that WBVT promotes an increase in blood BDNF levels, with concomitant improvement in lower limb muscle strength, aerobic capacity, clinical symptoms, and quality of life in women with FMS. This trial is registered with Brazilian Clinical Trials Registry (REBEC; RBR-38nbbx) (https://ensaiosclinicos.gov.br/rg/RBR-38nbbx).
Although High Intensity Interval Training (HIIT) are being associated to increase cardiovascular and metabolic adaptation, there is controversy and limited information about the effects of HIIT on ...hippocampal oxidative stress, pro- and anti-inflammatory cytokines balance and neurotrophic status. Thus, this study evaluated the effects of six weeks of HIIT on hippocampal redox state (oxidative damage and enzymatic and non-enzymatic antioxidant defenses), neuroimmune mediators (TNFα, IL-6, IL-1β and IL-10) and brain-derived neurotrophic (BDNF) levels. After six weeks of HIIT young adults male Wistar rats presented reduced oxidative damage and increased enzymatic (superoxide dismutase) and non-enzymatic activity in hippocampus. Moreover HIIT induced a decrease in cytokine content (TNFα, IL-6, IL-1β and IL-10) and enhanced hippocampal BDNF levels. In conclusion, the present study showed for the first time a positive effect of six weeks of HIIT on reducing hippocampal oxidative stress by decreasing lipoperoxidation and inflammatory markers, as well enhancing antioxidant defenses and BDNF content.
•HIIT modulates hippocampal oxidative stress.•HIIT modulates hippocampal inflammatory mediators.•HIIT increases hippocampal BDNF levels.
•Erg6 is required for Cryptococcus neoformans high temperature growth.•ERG6 deletion impairs susceptibility to stress and antifungal agents.•Sterol membrane composition affects virulence of human ...fungal pathogen.
Ergosterol is the most important membrane sterol in fungal cells and a component not found in the membranes of human cells. We identified the ERG6 gene in the AIDS-associated fungal pathogen, Cryptococcus neoformans, encoding the sterol C-24 methyltransferase of fungal ergosterol biosynthesis. In this work, we have explored its relationship with high-temperature growth and virulence of C. neoformans by the construction of a loss-of-function mutant. In contrast to other genes involved in ergosterol biosynthesis, C. neoformans ERG6 is not essential for growth under permissive conditions in vitro. However, the erg6 mutant displayed impaired thermotolerance and increased susceptibility to osmotic and oxidative stress, as well as to different antifungal drugs. Total lipid analysis demonstrated a decrease in the erg6Δ strain membrane ergosterol content. In addition, this mutant strain was avirulent in an invertebrate model of C. neoformans infection. C. neoformans Erg6 was cyto-localized in the endoplasmic reticulum and Golgi complex. Our results demonstrate that Erg6 is crucial for growth at high temperature and virulence, likely due to its effects on C. neoformans membrane integrity and dynamics. These pathogen-focused investigations into ergosterol biosynthetic pathway components reinforce the multiple roles of ergosterol in the response of diverse fungal species to alterations in the environment, especially that of the infected host. These studies open perspectives to understand the participation of ergosterol in mechanism of resistance to azole and polyene drugs. Observed synergistic growth defects with co-inhibition of Erg6 and other components of the ergosterol biosynthesis pathway suggests novel approaches to treatment in human fungal infections.
In this study, we screened sixty medicinal plant species from the
Brazilian savanna ("cerrado") that could contain useful compounds for
the control of tropical diseases. The plant selection was based ...on
existing ethnobotanic information and interviews with local healers.
Plant extracts were screened for: (a) molluscicidal activity against
Biomphalaria glabrata , (b) toxicity to brine shrimp ( Artemia salina
L.), (c) antifungal activity in the bioautographic assay with
Cladosporium sphaerospermum and (d) antibacterial activity in the agar
diffusion assay against Staphylococcus aureus , Escherichia coli ,
Bacillus cereus and Pseudomonas aeruginosa. Forty-two species afforded
extracts that showed some degree of activity in one or more of these
bioassays.
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