Regular Aerobic Training Research Articles

Treinamento aeróbico prévio à compressão nervosa: análise da morfometria muscular de ratos

INTRODUÇÃO: Ciatalgia origina-se da compressão do nervo isquiático e implica em dor, parestesia, diminuição da força muscular e hipotrofia. O exercício físico é reconhecido na prevenção e reabilitação de lesões, porém quando em sobrecargas pode aumentar o risco de lesões e consequente déficit funcional. OBJETIVO: Avaliar efeitos de treinamento aeróbico prévio a modelo experimental de ciatalgia em relação a parâmetros morfométricos dos músculos sóleos de ratos. MATERIAIS E MÉTODOS: 18 ratos divididos em três grupos: simulacro (mergulho, 30 segundos); exercício regular (natação, dez minutos diários); e treinamento aeróbico progressivo (natação em tempos progressivos de dez a 60 minutos diários). Ao final de seis semanas de exercício, os ratos foram submetidos ao modelo experimental da ciatalgia. No terceiro dia após a lesão, foram eutanasiados e tiveram seus músculos sóleos dissecados, pesados e preparados para análise histológica. Variáveis analisadas: peso muscular, área de secção transversa e diâmetro médio das fibras musculares. RESULTADOS: Observou-se diferença estatisticamente significativa para todos os grupos quando se comparou músculo controle e aquele submetido à lesão isquiática. A análise intergrupos não apresentou diferença estatisticamente significativa para nenhuma das variáveis analisadas. CONCLUSÃO: Tanto o exercício físico regular quanto o treinamento aeróbico não produziram efeitos preventivos ou agravantes às consequências musculares da inatividade funcional após ciatalgia.

722 – Effect of regular aerobic exercise on depression in postmenopausal women

Background and objective Most women that reached menopause, experience depression. This study was done with this purpose to investigate the effects of regular aerobic exercise on depression in postmenopausal women. Methods In this experimental study, twenty six postmenopausal depressed women with age of 45-55 years, who sampled randomly in 2 groups (control and experimental), were participated in this investigation. The experimental group followed exercise training program including walking three times a week, for 3 months. But control group did not participate in any exercise program. depression level was measured before and after exercise. Findings Mean of depression in experimental group before exercise training relative to after exercise training were significantly decreased. Conclusion The results of present study demonstrated that regular aerobic exercise training decrease depression symptom. So, the authorities should apply strategies to decrease depression symptoms by changing life style from inactivity to exercise training in order to support postmenopausal women somatic health.

Effects of Different Types of Acute and Chronic (Training) Exercise on Glycaemic Control in Type 1 Diabetes Mellitus

Objective Exercise has been accepted and generally recommended for the management of type 1 diabetes mellitus (T1D) and for improving the overall quality of life in affected individuals. This meta-analysis was conducted to determine the overall effects of exercise (acute bouts of exercise and chronic exercise [or training]) on acute and chronic glycaemic control in patients with T1D, the effects of different types of exercise on glycaemic control and which conditions are required to obtain these positive effects. Methods PubMed, ISI Web of Knowledge and SPORTDiscus™ were consulted to identify studies on T1D and exercise. Cohen's d statistics were used for calculating mean effect sizes (ES) as follows: small d = 0.3, medium d = 0.5 and large d = 0.8. Ninety-five percent confidence intervals (95% CIs) were used to establish the significance of our findings. Results From a total of 937 studies, 33 that met the inclusion criteria were selected. Nine studies were used to calculate the ES of a single bout of aerobic exercise; 13 studies to calculate the ES of aerobic training; 2 studies to calculate the ES of strength training; 4 studies to calculate the ES of combined (aerobic and strength) training and 6 studies to calculate the ES of high-intensity exercise (HIE) and training. ES for exercise on acute glycaemic control were large, while they were small for chronic glycaemic control. Aerobic exercise, resistance exercise, mixed exercise (aerobic combined with resistance training) and HIE acutely decreased blood glucose levels. To prevent late-onset hypoglycaemic episodes, the use of single bouts of sprints into an aerobic exercise can be recommended. This meta-analysis also showed that a regular exercise training programme has a significant effect on acute and chronic glycaemic control, although not all exercise forms showed significant results. Specifically, aerobic training is a favourable tool for decreasing chronic glycaemic control, while resistance training, mixed and HIE did not significantly improve chronic glycaemic control. Although, this meta-analysis showed there was a tendency for improvement in glycaemic control due to resistance training or resistance training combined with endurance training, there were not enough studies and/or subjects to confirm this statistically. Conclusions Based on this meta-analysis, we can conclude that the addition of brief bouts of high-intensity, sprint-type exercise to aerobic exercise can minimize the risk of sustaining a hypoglycaemic episode. We can also conclude that only regular aerobic training will improve the glycated haemoglobin level of a patient with T1D.

Effects of Different Types of Acute and Chronic (Training) Exercise on Glycaemic Control in Type 1 Diabetes Mellitus

Exercise has been accepted and generally recommended for the management of type 1 diabetes mellitus (T1D) and for improving the overall quality of life in affected individuals. This meta-analysis was conducted to determine the overall effects of exercise (acute bouts of exercise and chronic exercise [or training]) on acute and chronic glycaemic control in patients with T1D, the effects of different types of exercise on glycaemic control and which conditions are required to obtain these positive effects. PubMed, ISI Web of Knowledge and SPORTDiscus™ were consulted to identify studies on T1D and exercise. Cohen's d statistics were used for calculating mean effect sizes (ES) as follows: small d = 0.3, medium d = 0.5 and large d = 0.8. Ninety-five percent confidence intervals (95% CIs) were used to establish the significance of our findings. From a total of 937 studies, 33 that met the inclusion criteria were selected. Nine studies were used to calculate the ES of a single bout of aerobic exercise; 13 studies to calculate the ES of aerobic training; 2 studies to calculate the ES of strength training; 4 studies to calculate the ES of combined (aerobic and strength) training and 6 studies to calculate the ES of high-intensity exercise (HIE) and training. ES for exercise on acute glycaemic control were large, while they were small for chronic glycaemic control. Aerobic exercise, resistance exercise, mixed exercise (aerobic combined with resistance training) and HIE acutely decreased blood glucose levels. To prevent late-onset hypoglycaemic episodes, the use of single bouts of sprints into an aerobic exercise can be recommended. This meta-analysis also showed that a regular exercise training programme has a significant effect on acute and chronic glycaemic control, although not all exercise forms showed significant results. Specifically, aerobic training is a favourable tool for decreasing chronic glycaemic control, while resistance training, mixed and HIE did not significantly improve chronic glycaemic control. Although, this meta-analysis showed there was a tendency for improvement in glycaemic control due to resistance training or resistance training combined with endurance training, there were not enough studies and/or subjects to confirm this statistically. Based on this meta-analysis, we can conclude that the addition of brief bouts of high-intensity, sprint-type exercise to aerobic exercise can minimize the risk of sustaining a hypoglycaemic episode. We can also conclude that only regular aerobic training will improve the glycated haemoglobin level of a patient with T1D.

Change of Plasma Osteoprotegerin and its Association with Endothelial Dysfunction before and after Exercise in Hashimoto’s Thyroiditis with Euthyroidism

Osteoprotegerin (OPG) is a recently identified inhibitor of bone resorption. Recent studies indicated that OPG also acts as an important regulatory molecule in the vasculature. The purpose of this study was to investigate the change of OPG and its associations with endothelial function before and after exercise training in Hashimoto's thyroiditis (HT) with euthyroidism.The study subjects included 62 newly diagnosed sedentary Chinese Han HT women with euthyroidism and 28 sedentary Chinese Han female healthy subjects. All individuals participated in an exercise training of 6 months. Plasma OPG concentrations were measured in duplicate by a sandwich enzyme-linked immunosorbent assay, and high resolution ultrasound was used to measure brachial artery diameter at rest, after reactive hyperemia, and after sublingual glyceryltrinitrate. The OPG concentration in HT patients with euthyroidism before exercise was 3.0±0.81 ng/L, which was significantly higher than that in control subjects (2.44±0.24 ng/L, p<0.001). After 6 months of exercise, OPG levels decreased markedly (2.40±0.61 ng/L, p<0.001). Flow-mediated dilation (FMD) in HT patients with euthyroidism before exercise was 4.06±0.78%, which was significantly lower than that in control subjects (5.54±0.61%, p<0.001), and it improved markedly after 6 months of exercise (5.0±0.79, p<0.001). The absolute changes in OPG showed significant correlation with the changes in FMD (r= - 0.432, p=0.001), TBARS (r= - 0.370, p=0.004) and CRP (r= - 0.503, p<0.001). The current study demonstrates that plasma OPG levels increased significantly at baseline, decreased dramatically after 6 months regular aerobic exercise training, and are correlated with endothelium-dependent arterial dilation in HT patients with euthyroidism.

Protective effect of regular aerobic training on inflammatory and toxicity markers of lung tissue in L-NAME-induced hypertension

Pharmacognostical standardization and toxicity profile of the methanolic leaf extract of Plectranthus amboinicus (Lour) SprengPreeja G. Pillai, P. Suresh, Gayatri Aggarwal, Gaurav Doshi, Vidhi Bhatia

Habitual aerobic exercise increases plasma pentraxin 3 levels in middle-aged and elderly women

Chronic inflammation that occurs with aging is one of the risk factors for cardiovascular disease. Regular exercise may prevent cardiovascular morbidity by decreasing chronic systematic inflammation. Additionally, excess inflammation can be reduced by the anti-inflammatory protein pentraxin 3 (PTX3). Thus, both habitual exercise and PTX3 have an anti-inflammatory effect. However, it is unclear whether regular exercise leads to increased plasma PTX3 concentration. In the present study, we investigated the effects of regular aerobic exercise on plasma PTX3 concentration in middle-aged and elderly women. Twenty-two postmenopausal women (60 ± 6 years) were randomly divided evenly into 2 groups (i.e., exercise intervention and control). Subjects in the exercise group completed 2 months of regular aerobic exercise training (walking and cycling, 30-45 min, 3-5 days·week⁻¹). Before and after the intervention, we evaluated plasma PTX3 concentration, peak oxygen uptake, blood chemistry, and arterial distensibility (carotid arterial compliance and β-stiffness) in all participants. There were no significant differences in baseline parameters between the 2 groups. Plasma PTX3 concentration was significantly increased in the exercise group after the intervention (p < 0.05). High-density lipoprotein cholesterol, peak oxygen uptake, and arterial compliance were also significantly increased (p < 0.05), while β-stiffness was markedly decreased (p < 0.01) after the intervention. On the other hand, there was no change in the parameters tested in the control group. This study demonstrates that regular aerobic exercise increases plasma PTX3 concentration with improvement of high-density lipoprotein cholesterol, peak oxygen uptake, and arterial distensibility in postmenopausal women.

Trainingstherapie bei kardiologischen Patienten (Sportkardiologie)

Clinical application of physical exercise has developed into an evidence-based therapeutic option for cardiovascular diseases, especially coronary artery disease (CAD) and chronic heart failure (CHF). In CAD regular physical exercise training partially corrects endothelial dysfunction and leads to an economization of left ventricular function. Meta-analyses have shown a reduction of angina pectoris symptoms and a decrease of total and cardiovascular mortality by regular aerobic exercise training. Endurance training for CHF reduces cardiac afterload by correcting peripheral endothelial dysfunction und leads to a better left ventricular function. In addition exercise training reduces the adrenergic tone and the stimulation of the renin-angiotensin-aldosterone system in CHF. Exercise training provides positive effects on the metabolism and function of skeletal muscle (e.g. reduced inflammation and oxidative stress). Supervised regular physical exercise training in CHF is safe and has improved the morbidity in clinical studies. Thus aerobic exercise training is an important component of therapeutic management of stable CAD and CHF with a class 1a recommendation in the current guidelines.

8주 유산소 트레이닝이 중년의 제 2형 당뇨(T2DM)환자의 혈청지질 및 신장기능에 미치는 영향

본 연구의 목적은 8주 유산소 트레이닝이 제 2형 당뇨(T2DM)환자의 콜레스테롤과 신장기능에 미치는 영향을 규명하기 위함이다. 피험자는 총 4명(남 3, 여 1)이며 8주 유산소 걷기 트레이닝의 운동강도는 최대심박수(<TEX>$HR_{max}$</TEX>)의 60~75%, 주당 3~5 회, 20~45 분간 실시되었으며 다음과 같은 결과를 얻었다. 신체적 특성 중 체지방률과 공복시 혈당은 8주 유산소 걷기 트레이닝 후 유의하게(<TEX>$p$</TEX> <0.05) 감소함을 나타냈고, 혈중지질인 총 콜레스테롤(TC)과 중성지방(TG)도 유의한 감소를 나타냈다. 그러나 신장기능[BUN, uric acids, creatinine]은 유의한 변화를 나타내지 못했다. 결과적으로 8주 유산소 트레이닝은 제 2형 당뇨(T2DM)와 당뇨병성 신증 환자의 1예에서 체지방률과 공복시혈당, 지질을 감소시키는데 영향을 미쳤지만 신장기능 증진에는 어떠한 영향도 미치지 못했다. The purpose of this study was to examine the effect of 8 weeks of aerobic exercise on serum lipids and kidney function in middle-aged T2DM patients. Subjects participated in aerobic exercise training during 8 wk. They started with an exercise intensity of <TEX>$HR_{max}$</TEX> 60-75%, 20~45 minutes per day, 3~5 times a week. The results were compared to the baseline after 8 weeks. After the 8-week aerobic exercise routine, the body fat percentage and fasting glucose were significantly decreased, and the total cholesterol (TC) andtriglycerides (TG) were significantly decreased. Additionally, kidney function (Blood Urea Nitrogen (BUN], uric acids, and creatinine) was not significantly changed. In conclusion, a regular 8-week aerobic exercise training routine may improve serum lipids; however, kidney function (BUN, uric acids, and creatinine) did not change in middle-age type 2 diabetes mellitus (T2DM) and T2DM in diabetic nephropathy patients.

Differences of functional fitness in adults after 9 months of combined exercise training program

The main objective of this study was to evaluate the incidence of physical intervention program related quality of life on a set of physical tests that determine the physical condition of adults. 128 adults, aged between 50-70 years old, participated in a combined exercise training program, 3 sessions per week (two Physical Fitness Exercises and one swimming), during a period of 9 months. Their physical condition was assessed at the beginning and at the end of the study by the Senior Fitness Test (SFT). Results show significant improvements in the strength parameters of the legs and arms (p<0.01) and in the range of motion in the shoulders and trunk (p<0.05), no significant differences were found in tests of agility and resistance. These results suggest that participation in regular physical exercise programs, both aerobic and strength training causes a number of favourable responses that contribute to healthy aging and may play a role in the prevention or reduction of functional decline in older adults.

Blood Flow Restricted Exercise and Vascular Function

It is established that regular aerobic training improves vascular function, for example, endothelium-dependent vasodilatation and arterial stiffness or compliance and thereby constitutes a preventative measure against cardiovascular disease. In contrast, high-intensity resistance training impairs vascular function, while the influence of moderate-intensity resistance training on vascular function is still controversial. However, aerobic training is insufficient to inhibit loss in muscular strength with advancing age; thus, resistance training is recommended to prevent sarcopenia. Recently, several lines of study have provided compelling data showing that exercise and training with blood flow restriction (BFR) leads to muscle hypertrophy and strength increase. As such, BFR training might be a novel means of overcoming the contradiction between aerobic and high-intensity resistance training. Although it is not enough evidence to obtain consensus about impact of BFR training on vascular function, available evidences suggested that BFR training did not change coagulation factors and arterial compliance though with inconsistence results in endothelial function. This paper is a review of the literature on the impact of BFR exercise and training on vascular function, such as endothelial function, arterial compliance, or other potential factors in comparison with those of aerobic and resistance training.

Does regular aerobic training affect basal leptin level (difference between male and female)?

There is discrepancy about the effects of regular exercise training on basal leptin level and most of the existing data have been collected from obese/thin subjects. In this study, the effects of one year aerobic exercise was investigated in normal weight untrained healthy volunteer male and female subjects. The sample included 60 non-athletes, male and female university students. First, all samples were randomly divided into four groups. The practice program including selected aerobic exercises and volleyball drills with specific intensity was applied. The blood samples of subjects were taken once 24 h before the first section of the exercise program and 24 h after the last section of the exercise program. Resting plasma leptin level was determined using ELISA method in pre and posttest and in paired sample T test, whereas one way and two way (factorial) ANOVA was used to analyze the data. Studies show that basal plasma leptin levels in healthy young non-athlete individuals in response to regular exercise in the long term did not fluctuate.Aerobic exercise for one year showed no significant effect on plasma leptin levels (that is about the role of fat tissue as the most significant source of leptin), and it seems that it occurs because fat tissue in subjects did not change. Key words: Aerobic exercise, leptin, long- term, non-athlete.

Análisis de los componentes espectrales de la variabilidad cardíaca en hombres jóvenes entrenados: comparación del entrenamiento aeróbico y anaeróbico

IntroductionHeart rate variability (HRV) is a non-invasive tool for studying autonomic modulation of cardiovascular function. According to the specificity principle of training, each type of exercise causes specific adaptations. However, whether this concept also applies to HRV has not been established. The aim of this study was to compare the spectral components of HRV between endurance-trained and strength-trained young men. Material and methodsCross sectional analytical descriptive study. Spectral components of HRV at rest were analysed from short records in 12 runners, 10 weight lifters and 11 not physically active control subjects. ResultsEndurance-trained subjects showed the lowest values in the low frequency component (LF) and the highest values at high frequency (HF), but these differences were not statistically significant. Total spectral power was similar in all groups (P=.103), as well as the ratio of low frequency components divided into high frequency (LF/HF) (P=.094). Heart rate at rest in aerobically trained group was significantly lower compared to strength-trained group (P<.01) and controls (P<.001). ConclusionsThe results showed no effect of long-term regular aerobic or anaerobic physical training, on spectral components of HRV. In our aerobically trained subjects, rest bradycardia was not explained by changes in the autonomic control of cardiovascular function.

The effect of three-month pre-season preparatory period and short-term exercise on plasma leptin, adiponectin, visfatin, and ghrelin levels in young female handball and basketball players.

The aim of the study was to assess the effect of a 3-month pre-season preparatory period and shortterm moderate aerobic exercise and intensive fitness and speed exercise on adipokine and ghrelin levels in young female handball and basketball players. Fifty healthy young female professional basketball and handball players were enrolled into the study before the opening of the season (after a 2-month holiday with no training or dietary restrictions). Serum estradiol and plasma leptin, adiponectin, visfatin, and ghrelin levels were determined at the beginning and the end of a 3-month period of moderate aerobic training. Plasma adipokines and ghrelin levels were additionally assessed after 2 h of moderate aerobic exercise or after intensive fitness and speed exercise training. Long-term moderate aerobic exercise was followed by a significant decrease in plasma ghrelin and leptin levels (921±300 vs 575±572 pg/ml, p<0.001 and 16.4±15.6 vs 11.8±16.3 ng/ml, p<0.01, respectively); plasma adiponectin and visfatin remained unchanged. No changes were observed in plasma ghrelin and leptin levels after short-term moderate aerobic exercise or after intensive fitness and speed exercise. Plasma visfatin concentration increased significantly after short-term moderate aerobic exercise (22.1±8.7 vs 27.6±9.0 ng/ml, p<0.001), whilst adiponectin increased after intensive fitness and speed exercise (16.7±7.8 vs 21.0±9.8 μg/ml, p<0.001). Regular moderate aerobic training in preparation for the match season is followed by a decline in circulating leptin and ghrelin levels even in athletes without body weight changes. Short-term intensive fitness and moderate aerobic exercise seem to modulate the production of different adipokines.

Aerobic exercise attenuates pulmonary injury induced by exposure to cigarette smoke

It has recently been suggested that regular exercise reduces lung function decline and risk of chronic obstructive pulmonary disease (COPD) among active smokers; however, the mechanisms involved in this effect remain poorly understood. The present study evaluated the effects of regular exercise training in an experimental mouse model of chronic cigarette smoke exposure. Male C57BL/6 mice were divided into four groups (control, exercise, smoke and smoke+exercise). For 24 weeks, we measured respiratory mechanics, mean linear intercept, inflammatory cells and reactive oxygen species (ROS) in bronchoalveolar lavage (BAL) fluid, collagen deposition in alveolar walls, and the expression of antioxidant enzymes, matrix metalloproteinase 9, tissue inhibitor of metalloproteinase (TIMP)1, interleukin (IL)-10 and 8-isoprostane in alveolar walls. Exercise attenuated the decrease in pulmonary elastance (p<0.01) and the increase in mean linear intercept (p=0.003) induced by cigarette smoke exposure. Exercise substantially inhibited the increase in ROS in BAL fluid and 8-isoprostane expression in lung tissue induced by cigarette smoke. In addition, exercise significantly inhibited the decreases in IL-10, TIMP1 and CuZn superoxide dismutase induced by exposure to cigarette smoke. Exercise also increased the number of cells expressing glutathione peroxidase. Our results suggest that regular aerobic physical training of moderate intensity attenuates the development of pulmonary disease induced by cigarette smoke exposure.

The relationship between heart period variability and VO 2 peak response to high intensity intermittent exercise training

Introduction: Significant individual differences in the VO2max response to regular aerobic training have been documented in healthy adults after standardized exercise programs. In prior research the mean improvements in VO2max have ranged from a 5% decrease to a 40% increase. Recently, baseline autonomic nervous system status has been shown to be a contributor to the training response. High frequency power of heart period variability (HPV), a measure of vagal influence on the heart, has been shown to predict training response independently after adjustment for age, baseline fitness, and BMI.

Impaired Leg Vasodilatory Function After Stroke

Resting and reactive hyperemic leg blood flows are significantly reduced in the paretic compared with the nonparetic limb after disabling stroke. Our objective was to compare the effects of regular treadmill exercise (TM) with an active control regimen of supervised stretching (CONTROL) on peripheral hemodynamic function. This intervention study used a randomized, controlled design, in which participants were randomized with stratification according to age and baseline walking capacity to ensure approximate balance between the 2 groups. Fifty-three chronic, ischemic stroke participants (29 TM and 24 CONTROL) with mild to moderate hemiparetic gait completed bilateral measurements of lower leg resting and reactive hyperemic blood flow using venous occlusion strain gauge plethysmography before and after the 6-month intervention period. Participants also underwent testing to track changes in peak aerobic fitness across time. Resting and reactive hyperemic blood flows were significantly reduced in the paretic compared with the nonparetic limb at baseline before any intervention (-28% and -34%, respectively, P<0.01). TM increased both resting and reactive hyperemic blood flow in the paretic limb by 25% compared with decreases in CONTROL (P<0.001, between groups). Similarly, nonparetic leg blood flow was significantly improved with TM compared with controls (P<0.001). Peak aerobic fitness improved by 18% in TM and decreased by 4% in CONTROL (P<0.01, between groups), and there was a significant relationship between blood flow change and peak fitness change for the group as a whole (r=.30, P<0.05). Peripheral hemodynamic function improves with regular aerobic exercise training after disabling stroke.

Reference change values of blood analytes from physically active subjects

The analysis of blood constituents allows the detection of various physiological or pathological states when their values are increased or decreased in relation to a well-defined reference group or to themselves if monitored longitudinally. In the latter case, it is important to know the reference change value (RCV) or critical difference, which defines the percentage change that should be exceeded-given the analytical and biological variations inherent to a particular test, in that there is a significant difference between the two consecutive measurements. Our objective was to calculate the biological variation, analytical variation and RCV of the biochemical and hematological parameters in subjects undergoing 4 months of regular aerobic training. Blood samples (10 mL) were collected monthly from 56 male subjects (17-19 years old). Creatine kinase and aspartate aminotransferase activities, total cholesterol, triglycerides, uric acid, C-reactive protein, alpha-1-acid glycoprotein, creatinine and urea concentrations were measured in sera using an Autolab Boehringer analyzer. Hemogram were obtained from total blood using KX-21 N SYSMEX equipment. The RCV values for leukocytes and all biochemical analytes were elevated compared to the literature values of sedentary subjects. On the other hand, the RCV values for red blood cell count were slightly lower in physically active than in sedentary individuals. Knowledge of analyte RCV values within physically active subjects should improve the sensitivity/specificity of the hematological and biochemical alterations induced by training or the use of recombinant form of erythropoietin through blood parameter analysis, particularly in cases of longitudinal monitoring.

Respiratory muscle training and maximum aerobic power in hypoxia

In a recent paper, Keramidas et al. (2010) investigated the effects of respiratory muscle training (RMT) on endurance exercise performance in normoxia (N) and hypoxia (H; FIO2 = 0.12). Participants were randomly assigned either to RMT or control training group. Both groups performed regular (1 h/day, 5 days/week at 50% of peak power output) aerobic training on a cycle ergometer, while RMT group performed an additional specific training programme of respiratory muscles (isocapnic hyperpnoea) prior to the cycle ergometry. After 4 weeks of training, both groups enhanced maximum oxygen uptake _ VO2max in N, but only the RMT group improved _ VO2max (only specific, not absolute) significantly in H. The enhanced _ VO2max in H in the RMT group was accompanied by increased maximum ventilation _ VE , but at an identical peak power output, most likely resulting in an increased metabolic demand of the respiratory muscles. However, in this study, peak power output was calculated as the last workload completed of a ramp test (30 W/min). If this is the case, peak power output would be a supramaximal power, which both aerobic and anaerobic energy sources would contribute to, and thus cannot be defined as the maximum aerobic mechanical power, which corresponds to the lowest power requiring a _ VO2 equal to _ VO2max. Always, whether in N or in H, an increase in _ VO2max is accompanied by an increase in maximum mechanical power. In a similar paper, Esposito et al. (2010) assessed the effects of 8 weeks RMT (isocapnic hyperpnoea, 5 training sessions per week, 10–20 min each including warm up; the volume and the frequency of respiratory cycles were increased progressively, based on participants’ response to training work loads) on _ VO2max in N and H (FIO2 = 0.11). After 8 weeks of RMT, no changes in cardiorespiratory and metabolic variables were detected at maximal exercise in N. On the contrary, in H _ VE and alveolar ventilation _ VA at maximal exercise were significantly higher than in pre-training condition. Accordingly, alveolar O2 partial pressure (PAO2 ) after RMT significantly increased by *10%. Nevertheless, arterial PO2 and _ VO2max did not change with respect to pre-training condition. Thus, the authors provided evidence that RMT did not have any effect on _ VO2max, under either normoxic or hypoxic condition. They concluded that in H, the significant increase in _ VE and _ VA at maximum exercise after RMT lead to higher alveolar but not arterial PO2 values, revealing an increased A–a gradient. Thus, a possible role of increased ventilation–perfusion mismatch was suggested. According to multifactorial models of _ VO2max limitation (di Prampero 1985; di Prampero and Ferretti 1990), the O2 transfer from ambient air to mitochondria is set by a cascade of resistances in series, each resistance being overcome by a specific O2 partial pressure gradient. Four major resistances have been identified in the studies cited above (1) ventilatory (RV) between ambient and alveoli; (2) lung (RL) between alveoli and arterial blood; (3) circulatory (RQ) between arterial blood and muscle capillaries; (4) peripheral (Rp) between muscle capillaries and Communicated by Susan Ward.

Effects of ageing and fitness on skin-microvessel vasodilator function in humans

The impact of cardiopulmonary fitness (VO(2max)) on the age-related decline in skin-microvessel vasodilator function has not been fully established and the inter-relationships among different measures of microvascular vasodilator function are unknown. We used laser Doppler flowmetry to assess relative changes in forearm skin blood flow to various stimuli in three groups of adults: young (n = 15; 27 +/- 2 years), older sedentary (n = 14; 65 +/- 6 years) and older fit (n = 15; 61 +/- 5 years). Local-heating induced and post-occlusive hyperaemia responses were higher in the young and older fit groups compared to the older sedentary group (P < 0.05) and were moderately correlated with VO(2max) in the pooled cohort of older adults (r = 0.49-0.58; P < 0.05). Peak hyperaemia responses to acetylcholine and sodium nitroprusside were higher in young compared to older sedentary adults (P < 0.05) and were not associated with VO(2max) in older adults (P > 0.05). Associations among different measures of microvascular vasodilator function were generally moderate at best. In summary, the local heating and reactive hyperaemia data indicate that the age-related decline in skin-microvessel vasodilator function can be ameliorated through regular aerobic exercise training. As this is not supported by the iontophoresis data, we recommend that, when assessing microvascular function, the use of a single physiological or pharmacological stimulation coupled to laser Doppler flowmetry should be avoided. Finally, the moderate correlations between outcomes probably reflect the distinct mediators that are responsible for the vasodilator response to each test.