The slope of the VO2 slow component is associated with exercise intolerance during severe-intensity exercise

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Aerobic fitness level modulates the effects of prior supramaximal exercise on pulmonary VO2 response during moderate-intensity exercise

The aim of this study was to analyze the influence of aerobic fitness on the effects of prior exercise on VO2response during subsequent moderate-intensity exercise. After determination of the lactate threshold (LT) and maximal VO2 (VO2max). 14 untrained subjects (UG) and 14 well-trained cyclists (TG) performed on different days and in random order, rest to moderate-intensity exercise transitions (6 minutes at 80% of LT), preceded by either no prior exercise or prior supramaximal exercise (PSE: two bouts of 1 minute at 120% of VO2max, with a 1-minute rest in between). Baseline VO2 was significantly increased (p<0.05) by PSE in both groups (UG: 0.39 ± 0.06 vs. 0.51 ± 0.15 L·min -1;TG: 0.37 ± 0.06 vs. 0.58 ± 0.14 L·min -1). In the TG group, the steady state VO2 was significantly increased by PSE (TG: 2.21 ± 0.38 vs. 2.07 ± 0.27 L·min-1, p<0.05; UG: 1.60 ± 0.27 vs. 1.60 ± 0.29 L· min-1, p>0.05). It can be concluded that aerobic fitness level influences the effects of PSE on VO2 response during moderate-intensity exercise. [J Exerc Sci Fit • Vol 7 • No 1 • 48-54 • 2009].

Differences in acoustic and perceptual parameters of the voice between elderly and young women at habitual and high intensity

The present study aimed to compare elderly and young female voices in habitual and high intensity. The effect of increased intensity on the acoustic and perceptual parameters was assessed. Sound pressure level, fundamental frequency, jitter, shimmer, and harmonic to noise ratio were obtained at habitual and high intensity voice in a group of 30 elderly women and 30 young women. Perceptual assessment was also performed. Both groups demonstrated an increase in sound pressure level and fundamental frequency from habitual voice to high intensity voice. No differences were found between groups in any acoustic variables on samples recorded with habitual intensity level. No significant differences between groups were found in habitual intensity level for pitch, hoarseness, roughness, and breathiness. Asthenia and instability obtained significant higher values in elderly than young participants, whereas, the elderly demonstrated lower values for perceived tension and loudness than young subjects. Acoustic and perceptual measures do not demonstrate evident differences between elderly and young speakers in habitual intensity level. The parameters analyzed may lack the sensitivity necessary to detect differences in subjects with normal voices. Phonation with high intensity highlights differences between groups, especially in perceptual parameters. Therefore, high intensity should be included to compare elderly and young voice.

Low intensity physical exercise attenuates cardiac remodeling and myocardial oxidative stress and dysfunction in diabetic rats

We evaluated the effects of a low intensity aerobic exercise protocol on cardiac remodeling and myocardial function in diabetic rats. Wistar rats were assigned into four groups: sedentary control (C-Sed), exercised control (C-Ex), sedentary diabetes (DM-Sed), and exercised diabetes (DM-Ex). Diabetes was induced by intraperitoneal injection of streptozotocin. Rats exercised for 9 weeks in treadmill at 11 m/min, 18 min/day. Myocardial function was evaluated in left ventricular (LV) papillary muscles and oxidative stress in LV tissue. Statistical analysis was given by ANOVA or Kruskal-Wallis. Echocardiogram showed diabetic groups with higher LV diastolic diameter-to-body weight ratio and lower posterior wall shortening velocity than controls. Left atrium diameter was lower in DM-Ex than DM-Sed (C-Sed: 5.73 ± 0.49; C-Ex: 5.67 ± 0.53; DM-Sed: 6.41 ± 0.54; DM-Ex: 5.81 ± 0.50 mm; P < 0.05 DM-Sed vs C-Sed and DM-Ex). Papillary muscle function was depressed in DM-Sed compared to C-Sed. Exercise attenuated this change in DM-Ex. Lipid hydroperoxide concentration was higher in DM-Sed than C-Sed and DM-Ex. Catalase and superoxide dismutase activities were lower in diabetics than controls and higher in DM-Ex than DM-Sed. Glutathione peroxidase activity was lower in DM-Sed than C-Sed and DM-Ex. Conclusion. Low intensity exercise attenuates left atrium dilation and myocardial oxidative stress and dysfunction in type 1 diabetic rats.

Exercise tolerance can be enhanced through a change in work rate within the severe intensity domain: work above critical power is not constant

The characterization of the hyperbolic power-time (P-tlim) relationship using a two-parameter model implies that exercise tolerance above the asymptote (Critical Power; CP), i.e. within the severe intensity domain, is determined by the curvature (W') of the relationship. The purposes of this study were (1) to test whether the amount of work above CP (W>CP) remains constant for varied work rate experiments of high volatility change and (2) to ascertain whether W' determines exercise tolerance within the severe intensity domain. Following estimation of CP (208 ± 19 W) and W' (21.4 ± 4.2 kJ), 14 male participants (age: 26 ± 3; peak [Formula: see text]: 3708 ± 389 ml.min-1) performed two experimental trials where the work rate was initially set to exhaust 70% of W' in 3 ('THREE') or 10 minutes ('TEN') before being subsequently dropped to CP plus 10 W. W>CP for TEN (104 ± 22% W') and W' were not significantly different (P>0.05) but lower than W>CP for THREE (119 ± 17% W', P<0.05). For both THREE (r = 0.71, P<0.01) and TEN (r = 0.64, P<0.01), a significant bivariate correlation was found between W' and tlim. W>CP and tlim can be greater than predicted by the P-tlim relationship when a decrement in the work rate of high-volatility is applied. Exercise tolerance can be enhanced through a change in work rate within the severe intensity domain. W>CP is not constant.

High-intensity resistance training attenuates dexamethasone-induced muscle atrophy

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Short-term low-intensity blood flow restricted interval training improves both aerobic fitness and muscle strength

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

High-intensity interval training and hypertension: Maximizing the benefits of exercise?

Essential arterial hypertension is the most common risk factor for cardiovascular morbidity and mortality. Regular exercise is a well-established intervention for the prevention and treatment of hypertension. Continuous moderate-intensity exercise training (CMT) that can be sustained for 30 min or more has been traditionally recommended for hypertension prevention and treatment. On the other hand, several studies have shown that high-intensity interval training (HIT), which consists of several bouts of high-intensity exercise (~85% to 95% of HRMAX and/or VO2MAX lasting 1 to 4 min interspersed with intervals of rest or active recovery, is superior to CMT for improving cardiorespiratory fitness, endothelial function and its markers, insulin sensitivity, markers of sympathetic activity and arterial stiffness in hypertensive and normotensive at high familial risk for hypertension subjects. This compelling evidence suggesting larger beneficial effects of HIT for several factors involved in the pathophysiology of hypertension raises the hypothesis that HIT may be more effective for preventing and controlling hypertension.

Repeated sprint ability tests and intensity-time curvature constant to predict short-distance running performances

Anaerobic efforts are commonly required through repeated sprint during efforts in many sports, making the anaerobic pathway a target of training. Nevertheless, to identify improvements on such energetic way it is necessary to assess anaerobic capacity or power, which is usually complex. For this purpose, authors have postulated the use of short running performances to anaerobic ability assessment. Thus, the aim of this study was to find a relationship between running performances on anaerobic power, anaerobic capacity or repeated sprint ability. Methods Thirteen military performed maximal running of 50 (P50), 100 (P100) and 300 (P300) m on track, beyond of running-based anaerobic sprint test (RAST; RSA and anaerobic power test), maximal anaerobic running test (MART; RSA and anaerobic capacity test) and the W′ from critical power model (anaerobic capacity test). Results By RAST variables, peak and average power (absolute and relative) and maximum velocity were significantly correlated with P50 (r = −0.68, p = 0.03 and −0.76, p = 0.01; −0.83, p < 0.01 and −0.83, p < 0.01; and −0.78, p < 0.01), respectively. The maximum intensity of MART was negatively and significantly correlated with P100 (r = −0.59) and W′ was not statistically correlated with any of the performances. Conclusion MART and W′ were not correlated with short running performances, having a weak performance predicting probably due to its longer duration in relation to assessed performances. Observing RAST outcomes, we postulated that such a protocol can be used during daily training as short running performance predictor.

Intensity and interval of recovery in strength exercise influences performance: salivary lactate and alpha amylase as biochemical markers: a pilot study

Purpose The aim of the present study was to evaluate the effects of intensity and interval of recovery on performance in the bench press exercise, and the response of salivary lactate and alpha amylase levels. Methods Ten sportsman (aged 29 ± 4 years; body mass index 26 ± 2 kg/cm2 ) were divided in two groups: G70 (performing a bench press exercise at 70 % one repetition maximum—1RM), and G90 (performing a bench press exercise at 90 %—1RM). All groups were engaged in three intervals of recovery (30, 60 and 90 s). The maximum number of repetitions (MNR) and total weight lifted were computed, and saliva samples were collected 15 min before and after different intervals of recovery. For the comparison of the performance and biochemistry parameters, ANOVA tests for repeated measurements were conducted, with a significance level set at 5 %. Results In G70, the 30 s MNR was lower than the 60 and 90 s intervals of recovery (p\0.05) and the MNR with the 60 s interval of recovery was lower than the 90 s interval of recovery (p\0.041). Similarly, in G90 with the 30 s of interval of recovery, the sets were lower than observed with the 60 and 90 s (p\0.05), and MNR with the 60 s interval of recovery was lower than the 90 s interval of recovery (p\0.05). The salivary lactate showed an increase after exercise (p\0.05) when compared with the rest period for all groups, and no effects were observed for salivary alpha amylase. Conclusions Based on this result, the sets and reps can be modified to change the recovery time. This effect is very useful to improve the performance in relationship to different fitness levels.