1 Department of Physical Education, University of
Las Palmas de Gran Canaria, 35017 Las Palmas de Gran Canaria,
Canary Islands; 2 Instituto Nacional de
Educación Física de Leon, University of Leon, ...24071 Leon;
and 3 Centro de Tecnificación de Ciclismo,
Chiclana de la Frontera, 11130 Cádiz, Spain
The aim of this study was to
evaluate the effects of severe acute hypoxia on exercise performance
and metabolism during 30-s Wingate tests. Five endurance- (E) and five
sprint- (S) trained track cyclists from the Spanish National Team
performed 30-s Wingate tests in normoxia and hypoxia (inspired
O 2 fraction = 0.10). Oxygen deficit was estimated from
submaximal cycling economy tests by use of a nonlinear model. E
cyclists showed higher maximal O 2 uptake than S (72 ± 1 and 62 ± 2 ml · kg 1 · min 1 ,
P < 0.05). S cyclists achieved higher peak and mean
power output, and 33% larger oxygen deficit than E ( P < 0.05). During the Wingate test in normoxia, S relied more on
anaerobic energy sources than E ( P < 0.05); however, S
showed a larger fatigue index in both conditions ( P < 0.05). Compared with normoxia, hypoxia lowered O 2 uptake by
16% in E and S ( P < 0.05). Peak power output, fatigue index, and exercise femoral vein blood lactate concentration were not
altered by hypoxia in any group. Endurance cyclists, unlike S,
maintained their mean power output in hypoxia by increasing their
anaerobic energy production, as shown by 7% greater oxygen deficit and
11% higher postexercise lactate concentration. In conclusion,
performance during 30-s Wingate tests in severe acute hypoxia is
maintained or barely reduced owing to the enhancement of the anaerobic
energy release. The effect of severe acute hypoxia on supramaximal
exercise performance depends on training background.
fatigue; anaerobic power; anaerobic capacity; lactate
The gut microbiome is emerging as a key regulator of several metabolic, immune and neuroendocrine pathways
. Gut microbiome deregulation has been implicated in major conditions such as obesity, type ...2 diabetes, cardiovascular disease, non-alcoholic fatty acid liver disease and cancer
, but its precise role in aging remains to be elucidated. Here, we find that two different mouse models of progeria are characterized by intestinal dysbiosis with alterations that include an increase in the abundance of Proteobacteria and Cyanobacteria, and a decrease in the abundance of Verrucomicrobia. Consistent with these findings, we found that human progeria patients also display intestinal dysbiosis and that long-lived humans (that is, centenarians) exhibit a substantial increase in Verrucomicrobia and a reduction in Proteobacteria. Fecal microbiota transplantation from wild-type mice enhanced healthspan and lifespan in both progeroid mouse models, and transplantation with the verrucomicrobia Akkermansia muciniphila was sufficient to exert beneficial effects. Moreover, metabolomic analysis of ileal content points to the restoration of secondary bile acids as a possible mechanism for the beneficial effects of reestablishing a healthy microbiome. Our results demonstrate that correction of the accelerated aging-associated intestinal dysbiosis is beneficial, suggesting the existence of a link between aging and the gut microbiota that provides a rationale for microbiome-based interventions against age-related diseases.
While the internal load factors of whole-body vibration training have been widely investigated, the study of external load magnitude has been overlooked. Thus, the aim of the present study was to ...evaluate differences in whole-body vibration stimulus magnitude between static/dynamic whole-body vibration training at various vibration conditions. Four Pro 5 Plate vibration platforms were exposed to twelve different vibration conditions and a triaxial USB Impact X250-2 accelerometer was used to measure platform acceleration during each condition. Paired samples t-test was calculated to evaluate differences among amplitude, frequency, time of acceleration and time of deceleration of each platform at each vibration condition and during static (squat of 90degrees knee flexion) or dynamic exercise (from stand to 90degrees knee flexion squat). Also, the intra-class correlation coefficients were examined in order to assess the inter-instrument reliability. Peak-to-peak amplitude, frequency, time of acceleration and deceleration of the vibration platform were not modified by the type of exercise performed. Moreover, the four platforms tested showed high repeatability values during the execution of free vibration, static or dynamic squat in all vibration conditions. This study confirms that the vibration delivered by the Pro 5 Plate vibration platform is not modified during the realization of static or dynamic exercises.
Purpose
The aim of the study was to examine anthropometric characteristics and neuromuscular function in young judo athletes by sex, age and weight category.
Methods
146 child and cadet judo athletes ...were examined for height, body mass (BM), body fat percentage (BF), countermovement jump (CMJ), sit-and-reach (SAR) test and handgrip muscle strength (HMS).
Results
The results showed that male adolescents were taller, had more HMS, and less BF and flexibility than girls. Significant differences in the sex and weight category were observed, chiefly in BF and body mass index. There were no differences in time to peak force of HMS and CMJ.
Conclusions
Based on these findings, special attention should be put to heavy BM categories targeting low BF and high muscle mass, which might contribute to improved neuromuscular function and in turn contribute to the dynamics
randori
. This study might help profiling the young judoka taking into account sex, age and BM category.
We examined hormonal and haematological parameters and the profile of mood states (POMS) in top level judoists undertaking a 7-week competitive training period in a real contest.
Participants were 10 ...top level judoists belonging to the Spanish National Team. Training load was calculated by multiplying the training session intensity by the duration of the training session. The judoists competed in two official events on weeks 3 and 6 of the study.
Urinary catecholamines increased at the end of the competitive period. Serum cortisol increased during the weeks in which judoists competed, confirming the existence of and anticipatory cortisol response to exercise; although we failed to find serum testosterone increases. Because of leukocyte values did not change, except monocytes, we speculate that the intensity of training was not sufficiently high to evoke injury to muscle tissue. Anger, tension, and fatigue increased according with training load, suggesting that the training exercise led participants into a negative psychological state.
Findings indicate that during competitive periods, judoists suffer hormonal and mood changes according to training load and competitive events. Results support the usefulness of monitoring biological and psychological markers during season in order to adjust training loads and periods of recovery.
This study was undertaken to analyze the effects of different vibration recovery strategies via feet or hands on the number of repetitions performed and on mean velocity, peak velocity and blood ...lactate concentration during consecutive bench-press sets. 9 elite judo athletes performed 3 sets of bench press at 60% of one-repetition maximum (1RM), leading to failure and allowing a 180 s rest period between sets. During the rest period, 1 of the 3 following procedures was performed: 150 s rest plus 30 s push-up vibration exercise (Push-up), 150 s rest plus 30 s squat vibration exercise (Squat) or 180 s only rest (Passive). Statistical analysis revealed that the Squat condition resulted in a significant increase in the number of repetitions achieved, in comparison with all other rest strategies. However, kinematic parameters and blood lactate concentration were not affected by vibration. These data suggest that a vibration stimulus applied to the feet, between sets, can result in positive improvements in upper body resistance exercise performance. Although the mechanisms are not fully understood, this positive effect of vibration could be due to an increased motor cortex excitability and voluntary drive.
The aim of this study was to analyze changes in selected biological and psychological variables in a group of top level kayakers along a 42-week training season.
Eight top junior sprint kayakers ...(age=16.8±2.1) (5 men and 3 women) with international competitive experience participated in the research. During the 42-wk season the subjects were tested in three occasions: (T1) in the second week of the general training period, (T2) at the beginning of the specific training period, (T3) at the beginning of the competitive training period. Firstly, subjects were asked to complete the Recovery-Stress Questionnaire for Athletes (RESTQ-Sport) and the Profile of Mood States (POMS) questionnaires, and Borg´s rate of perceived exertion scale (RPE). Immediately after, blood samples were collected and white blood cells, creatine kinase (CK), C-reactive protein (CRP), myeloperoxidase protein levels (MPO) and glutathione status were determined. ANOVA with repeated measures was used to determine the differences between tests.
From the hematological and biochemical measures only total leukocytes changed significantly, increasing at T3 when compared to T1. There were no differences along the entire season in both RESTQ-Sport and POMS scores or indices. Concerning performance, the group improved their maximal strength (+17.4% in bench-press 1RM) and their specific-distance time (+9.8%). The main finding of the present study was that training was well-balanced between stress and recovery because while specific performance increased, signs of overtraining were not found.
Training monitoring in athletes should be performed in a multilevel approach using measurements of performance as well as biological or psychological parameters.
Technical variability of the GT3X accelerometer Santos-Lozano, Alejandro; Marín, Pedro J; Torres-Luque, Gema ...
Medical engineering & physics,
07/2012, Letnik:
34, Številka:
6
Journal Article
Recenzirano
Abstract To analyze the intra- and inter-instrument reliability of the ActiGraph GT3X accelerometer using a vibration table on each orthogonal axis and at five frequencies of motion. Ten GT3X units ...were subjected to a specific vibration using a motorized vibration table along the vertical, horizontal right–left and horizontal front–back axis, and at 1.1, 2.1, 3.1, 4.1 and 10.2 Hz. The 5 min data for each frequency were analyzed separately for frequency, axis effects, and inter- and intra-instrument variability. We found overall high intra-and inter-instrument reliability for the GT3X accelerometer at frequencies between 2.1 and 4.1 Hz. For frequencies ranging between 2.1 and 4.1 Hz, the intra-instrument coefficient of variation was ≤2.5%. The inter-instrument coefficient of variation ranged widely along axes and frequencies, with the lowest values (≤9%) corresponding to 2.1–4.1 Hz. The intra-class correlation coefficient for activity counts across frequencies and for all axes was 0.97. Overall, our findings support the use of the GT3X accelerometer as an accurate tool to estimate free-living physical activity, at least within those frequencies that are common to most types of human daily activities.
When evaluating dyspnea in patients with heart or lung disease it is useful to measure the quantity of ventilation needed to eliminate metabolically produced CO2 (i.e., the ventilatory efficiency). ...Mathematically, the relationship between ventilation (VE) and CO2 output is determined by the arterial CO2 pressure and the physiologic dead space-tidal volume ratio. We decided to determine how age, sex, size, fitness, and the type of ergometer influenced ventilatory efficiency in normal subjects. Three methods were compared for expressing this relationship: (1) the VE versus CO2 output slope below the ventilatory compensation point, commonly used by cardiologists for estimating the severity of heart failure; (2) the VE/CO2 output ratio at the anaerobic threshold, commonly used by pulmonologists; and (3) the lowest VE/CO2 output ratio during exercise, the latter parameter not previously reported. We studied 474 healthy adults, between 17 and 78 years of age during incremental cycle and treadmill cardiopulmonary exercise tests at three test sites, correcting the total VE for the equipment dead space. The lowest VE/CO2 output ratio was insignificantly different from the ratio at the anaerobic threshold, less variable than that for the slope relationship, and unaffected by the site, ergometer, and gas exchange measurement systems. The regression equation for the lowest VE/CO2 output ratio was 27.94 + 0.108 x age + (0.97 = F, 0.0 = M) - 0.0376 x height, where age is in years and height is in centimeters. We conclude that the lowest VE/CO2 output ratio is the preferred noninvasive method to estimate ventilatory inefficiency.
The analysis and interpretation of heart rate variability (HRV) during exercise is challenging not only because of the nonstationary nature of exercise, the time-varying mean heart rate, and the fact ...that respiratory frequency exceeds 0.4 Hz, but there are also other factors, such as the component centered at the pedaling frequency observed in maximal cycling tests, which may confuse the interpretation of HRV analysis. The objectives of this study are to test the hypothesis that a component centered at the running stride frequency (SF) appears in the HRV of subjects during maximal treadmill exercise testing, and to study its influence in the interpretation of the low-frequency (LF) and high-frequency (HF) components of HRV during exercise. The HRV of 23 subjects during maximal treadmill exercise testing is analyzed. The instantaneous power of different HRV components is computed from the smoothed pseudo-Wigner-Ville distribution of the modulating signal assumed to carry information from the autonomic nervous system, which is estimated based on the time-varying integral pulse frequency modulation model. Besides the LF and HF components, the appearance is revealed of a component centered at the running SF as well as its aliases. The power associated with the SF component and its aliases represents 22 ± 7% (median ± median absolute deviation) of the total HRV power in all the subjects. Normalized LF power decreases as the exercise intensity increases, while normalized HF power increases. The power associated with the SF does not change significantly with exercise intensity. Consideration of the running SF component and its aliases is very important in HRV analysis since stride frequency aliases may overlap with LF and HF components.
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