Increase In Maximal Oxygen Uptake Research Articles

Resveratrol blunts the positive effects of exercise training on cardiovascular health in aged men

Ageing is thought to be associated with decreased vascular function partly due to oxidative stress. Resveratrol is a polyphenol, which in animal studies has been shown to decrease atherosclerosis, and improve cardiovascular health and physical capacity, in part through its effects on Sirtuin 1 signalling and through an improved antioxidant capacity. We tested the hypothesis that resveratrol supplementation enhances training-induced improvements in cardiovascular health parameters in aged men. Twenty-seven healthy physically inactive aged men (age: 65 ± 1 years; body mass index: 25.4 ± 0.7 kg m(-2); mean arterial pressure (MAP): 95.8 ± 2.2 mmHg; maximal oxygen uptake: 2488 ± 72 ml O2 min(-1)) were randomized into 8 weeks of either daily intake of either 250 mg trans-resveratrol (n = 14) or of placebo (n = 13) concomitant with high-intensity exercise training. Exercise training led to a 45% greater (P < 0.05) increase in maximal oxygen uptake in the placebo group than in the resveratrol group and to a decrease in MAP in the placebo group only (-4.8 ± 1.7 mmHg; P < 0.05). The interstitial level of vasodilator prostacyclin was lower in the resveratrol than in the placebo group after training (980 ± 90 vs. 1174 ± 121 pg ml(-1); P < 0.02) and muscle thromboxane synthase was higher in the resveratrol group after training (P < 0.05). Resveratrol administration also abolished the positive effects of exercise on low-density lipoprotein, total cholesterol/high-density lipoprotein ratio and triglyceride concentrations in blood (P < 0.05). Resveratrol did not alter the effect of exercise training on the atherosclerosis marker vascular cell adhesion molecule 1 (VCAM-1). Sirtuin 1 protein levels were not affected by resveratrol supplementation. These findings indicate that, whereas exercise training effectively improves several cardiovascular health parameters in aged men, concomitant resveratrol supplementation can blunt these effects.

The relationship between cardiac autonomic function and maximal oxygen uptake response to high-intensity intermittent-exercise training

Major individual differences in the maximal oxygen uptake response to aerobic training have been documented. Vagal influence on the heart has been shown to contribute to changes in aerobic fitness. Whether vagal influence on the heart also predicts maximal oxygen uptake response to interval-sprinting training, however, is undetermined. Thus, the relationship between baseline vagal activity and the maximal oxygen uptake response to interval-sprinting training was examined. Exercisers (n = 16) exercised three times a week for 12 weeks, whereas controls did no exercise (n = 16). Interval-sprinting consisted of 20 min of intermittent sprinting on a cycle ergometer (8 s sprint, 12 s recovery). Maximal oxygen uptake was assessed using open-circuit spirometry. Vagal influence was assessed through frequency analysis of heart rate variability. Participants were aged 22 ± 4.5 years and had a body mass of 72.7 ± 18.9 kg, a body mass index of 26.9 ± 3.9 kg · m−2, and a maximal oxygen uptake of 28 ± 7.4 ml · kg−1 · min−1. Overall increase in maximal oxygen uptake after the training programme, despite being anaerobic in nature, was 19 ± 1.2%. Change in maximal oxygen uptake was correlated with initial baseline heart rate variability high-frequency power in normalised units (r = 0.58; P < 0.05). Thus, cardiac vagal modulation of heart rate was associated with the aerobic training response after 12 weeks of high-intensity intermittent-exercise. The mechanisms underlying the relationship between the aerobic training response and resting heart rate variability need to be established before practical implications can be identified.

Changes in breathing pattern and cycling efficiency as a result of training with added respiratory dead space volume

PurposeThe aim of this study was to evaluate the impact of training with added respiratory dead space volume (ARDSV) on changes in a breathing pattern and cycling efficiency.MethodsTwenty road cyclists were equally divided into an experimental (E) and control (C) group. All of them were involved in a training program that included endurance training (at moderate intensity) and interval training (at maximal intensity). During semi-weekly endurance training, ARDSV (1000cm3 tube) was introduced in the experimental group. Respiratory parameters, including, among others, oxygen uptake (VO&lt;SUB&gt;2&lt;/SUB&gt;), carbon dioxide excretion (VCO&lt;SUB&gt;2&lt;/SUB&gt;), end-tidal partial pressure of carbon dioxide (PETCO&lt;SUB&gt;2&lt;/SUB&gt;), pulmonary ventilation (VE), tidal volume (TV) and total work done during the tests (W), were measured before and after the experiment by a progressive and continuous test.ResultsHigher PETCO&lt;SUB&gt;2&lt;/SUB&gt; and TV in both groups during the progressive and continuous tests were observed. VCO&lt;SUB&gt;2&lt;/SUB&gt; increased in group E during continuous test, while for group C only in the first four minutes of the test. VO&lt;SUB&gt;2&lt;/SUB&gt; and VE increased only in group E during submaximal and maximal exercise. Total work increased during the continuous test in both groups (significantly higher in group C than E). However, total work during the progressive test increased only in group E.ConclusionsTraining with ARDSV improved exercise capacity at maximal effort and was associated with an increase in maximal oxygen uptake. On the other hand, this type of training lead to a decrease in cycling efficiency, reducing in effect the benefits associated with an increase in VO&lt;SUB&gt;2&lt;/SUB&gt;max and reducing the ability to perform submaximal effort.

Effect of six weeks of oral echinacea purpurea supplementation on nitric oxide production

Background Echinacea purpurea, a purple coneflower plant of the compositae family (Asteraceae), is native to North America and commonly used as an herbal supplement to enhance immune function. Echinacea purpurea has been shown to stimulate macrophage activity which is a known stimulator of nitric oxide (NO) production. Echinacea purpurea supplementation (8,000 mg·d) in untrained (42.5 ± 1.6 mL·kg·min) males was shown to elicit a 63% increase (p < 0.05) in serum erythropoietin (EPO) following two weeks of supplementation. This is supported in part by earlier findings which indicated that four weeks of Echinacea purpurea supplementation demonstrated a non-significant increase in maximal oxygen uptake (VO2max). It is plausible that Echinaceainduced EPO production may stimulate physiological responses independent of and/or in addition to erythropoiesis. There is also evidence suggesting EPO has vasculo-protective effects including the activation of endothelial nitric oxide synthase (eNOS). Based on these findings, a proposed non-hematological response to the Echinacea-induced increase in EPO could be enhanced NO production. The purpose of this investigation was to determine whether six weeks of oral Echinacea purpurea supplementation augmented NO production as a result of an Echinacea-induced increase in EPO and/or Echinaceainduced macrophage activity.

The perceptually regulated exercise test is sensitive to increases in maximal oxygen uptake

The aim of this study was to assess the sensitivity of a perceptually regulated exercise test (PRET) to predict maximal oxygen uptake (VO₂max) following an aerobic exercise-training programme. Sedentary volunteers were assigned to either a training (TG n = 16) or control (CG n = 10) group. The TG performed 30 min of treadmill exercise, regulated at 13 on the Borg Rating of Perceived Exertion (RPE) Scale, 3× per week for 8 weeks. All participants completed a 12-min PRET to predict VO₂max followed by a graded exercise test (GXT) to measure VO₂max before and after training. The PRET required participants to control the speed and incline on the treadmill to correspond to RPE intensities of 9, 11, 13 and 15. Predictive accuracy of extrapolation end-points RPE19 and RPE20 from a submaximal RPE range of 9-15 was compared. Measured VO₂max increased by 17 % (p < 0.05) from baseline to post-intervention in TG. This was reflected by a similar change in [VO₂max predicted from PRET when extrapolated to RPE 19 (baseline VO₂max: 31.3 ± 5.5, 30.3 ± 9.5 mL kg(-1) min(-1); post-intervention VO₂max: 36.7 ± 6.4, 37.4 ± 7.9 mL kg(-1) min(-1), for measured and predicted values, respectively). There was no change in CG (measured vs. predicted VO₂max: 39.3 ± 6.5; 40.3 ± 8.2 and 39.2 ± 7.0; 37.7 ± 6.0 mL kg(-1) min(-1)) at baseline and post-intervention, respectively. The results confirm that PRET is sensitive to increases in VO₂max following aerobic training.

Differentiated mTOR but not AMPK signaling after strength vs endurance exercise in training‐accustomed individuals

The influence of adenosine mono phosphate (AMP)-activated protein kinase (AMPK) vs Akt-mammalian target of rapamycin C1 (mTORC1) protein signaling mechanisms on converting differentiated exercise into training specific adaptations is not well-established. To investigate this, human subjects were divided into endurance, strength, and non-exercise control groups. Data were obtained before and during post-exercise recovery from single-bout exercise, conducted with an exercise mode to which the exercise subjects were accustomed through 10 weeks of prior training. Blood and muscle samples were analyzed for plasma substrates and hormones and for muscle markers of AMPK and Akt-mTORC1 protein signaling. Increases in plasma glucose, insulin, growth hormone (GH), and insulin-like growth factor (IGF)-1, and in phosphorylated muscle phospho-Akt substrate (PAS) of 160 kDa, mTOR, 70 kDa ribosomal protein S6 kinase, eukaryotic initiation factor 4E, and glycogen synthase kinase 3a were observed after strength exercise. Increased phosphorylation of AMPK, histone deacetylase5 (HDAC5), cAMP response element-binding protein, and acetyl-CoA carboxylase (ACC) was observed after endurance exercise, but not differently from after strength exercise. No changes in protein phosphorylation were observed in non-exercise controls. Endurance training produced an increase in maximal oxygen uptake and a decrease in submaximal exercise heart rate, while strength training produced increases in muscle cross-sectional area and strength. No changes in basal levels of signaling proteins were observed in response to training. The results support that in training-accustomed individuals, mTORC1 signaling is preferentially activated after hypertrophy-inducing exercise, while AMPK signaling is less specific for differentiated exercise.

High intensity interval training alters substrate utilization and reduces oxygen consumption in the heart

although exercise training induces hypertrophy with improved contractile function, the effect of exercise on myocardial substrate metabolism and cardiac efficiency is less clear. High intensity training has been shown to produce more profound effects on cardiovascular function and aerobic capacity than isocaloric low and moderate intensity training. The aim of the present study was to explore metabolic and mechanoenergetic changes in the heart following endurance exercise training of both high and moderate intensity. C57BL/6J mice were subjected to 10 wk treadmill running, either high intensity interval training (HIT) or distance-matched moderate intensity training (MIT), where HIT led to a pronounced increase in maximal oxygen uptake. Although both modes of exercise were associated with a 10% increase in heart weight-to-body weight ratio, only HIT altered cardiac substrate utilization, as revealed by a 36% increase in glucose oxidation and a concomitant reduction in fatty acid oxidation. HIT also improved cardiac efficiency by decreasing work-independent myocardial oxygen consumption. In addition, it increased cardiac maximal mitochondrial respiratory capacity. This study shows that high intensity training is required for induction of changes in cardiac substrate utilization and energetics, which may contribute to the superior effects of high compared with moderate intensity training in terms of increasing aerobic capacity.

Chronic CaMKII inhibition blunts the cardiac contractile response to exercise training

Activation of the multifunctional Ca2+/calmodulin-dependent protein kinase II (CaMKII) plays a critical role modulating cardiac function in both health and disease. Here, we determined the effect of chronic CaMKII inhibition during an exercise training program in healthy mice. CaMKII was inhibited by KN-93 injections. Mice were randomized to the following groups: sham sedentary, sham exercise, KN-93 sedentary, and KN-93 exercise. Cardiorespiratory function was evaluated by ergospirometry during treadmill running, echocardiography, and cardiomyocyte fractional shortening and calcium handling. The results revealed that KN-93 alone had no effect on exercise capacity or fractional shortening. In sham animals, exercise training increased maximal oxygen uptake by 8% (p < 0.05) compared to a 22% (p < 0.05) increase after exercise in KN-93 treated mice (group difference p < 0.01). In contrast, in vivo fractional shortening evaluated by echocardiography improved after exercise in sham animals only: from 25 to 32% (p < 0.02). In inactive mice, KN-93 reduced rates of diastolic cardiomyocyte re-lengthening (by 25%, p < 0.05) as well as Ca2+ transient decay (by 16%, p < 0.05), whereas no such effect was observed after exercise training. KN-93 blunted exercise training response on cardiomyocyte fractional shortening (63% sham vs. 18% KN-93; p < 0.01 and p < 0.05, respectively). These effects could not be solely explained by the Ca2+ transient amplitude, as KN-93 reduced it by 20% (p < 0.05) and response to exercise training was equal (64% sham and 47% KN-93; both p < 0.01). We concluded that chronic CaMKII inhibition increased time to 50% re-lengthening which were recovered by exercise training, but paradoxically led to a greater increase in maximal oxygen uptake compared to sham mice. Thus, the effect of chronic CaMKII inhibition is multifaceted and of a complex nature.

Maturation to elite status: a six-year physiological case study of a world champion rowing crew

This case study reports the results of a 6-year (2005-2010) follow-up study of a world-class rowing crew, the current world champions. The rowers were 15-16 years old and prospective competitors at the junior level when the study began in 2005, and we monitored their physical, physiological, and rowing ergometer performance data annually. Our findings indicated that over the 6-year period gains in stature, averaged across rowers, amounted to only +2 cm (+1%). In contrast, body mass increased by +9 kg (+10%) and fat-free mass by +11 kg (+15%). A significant linear trend (R (2) = 0.998, P < 0.001) and a +26% increase in maximal oxygen uptake (in L min(-1)) was evident from 2005 to 2009, resulting in a leveling-off and a crew average of ~6.6 L min(-1) (~70 mL kg(-1) min(-1)) during the last 2 years of assessment. Power output at anaerobic threshold increased by +23%, subsequently amounting to a crew average of 359 W in 2010. Oxygen uptake at anaerobic threshold, expressed as a percentage of maximal oxygen uptake, changed little and ranged between 82 and 85%. A curvilinear regression provided the best fit to describe the 6-year improvement (+7%) in 2000 m (R (2) = 0.984, P < 0.001) and 6000 m (R (2) = 0.989, P < 0.001) rowing ergometer performance times. Performance-related physical and physiological parameters seem to level-off at about 20 years of age, which may partly explain the corresponding stabilization in ergometer performance times over the last years of assessment.

Exercise training before cardiac-specific Serca2 disruption attenuates the decline in cardiac function in mice

In the heart, function of the sarco(endo)plasmic Ca(2+)-ATPase (SERCA2) is closely linked to contractility, cardiac function, and aerobic fitness. SERCA2 function can be increased by high-intensity interval training, whereas reduced SERCA2 abundance is associated with impaired cardiac function. The working hypothesis was, therefore, that exercise training before cardiomyocyte-specific disruption of the Serca2 gene would delay the onset of cardiac dysfunction in mice. Before Serca2 gene disruption by tamoxifen, untreated SERCA2 knockout mice (Serca2(flox/flox) Tg-αMHC-MerCreMer; S2KO), and SERCA2 FF control mice (Serca2(flox/flox), S2FF) were exercise trained by high-intensity interval treadmill running for 6 wk. Both genotypes responded to training, with comparable increases in maximal oxygen uptake (Vo(2max); 17%), left ventricle weight (15%), and maximal running speed (40%). After exercise training, cardiac-specific Serca2 gene disruption was induced in both exercise trained and sedentary S2KO mice. In trained S2KO, cardiac function decreased less rapidly than in sedentary S2KO. Vo(2max) remained higher in trained S2KO the first 15 days after gene disruption. Six weeks after Serca2 disruption, cardiac output was higher in trained compared with sedentary S2KO mice. An exercise-training program attenuates the decline in cardiac performance induced by acute cardiac Serca2 gene disruption, indicating that mechanisms other than SERCA2 contribute to the favorable effect of exercise training.

Increase in maximal oxygen uptake following 2-week walk training with blood flow occlusion in athletes

Walk training with blood flow occlusion (OCC-walk) leads to muscle hypertrophy; however, cardiorespiratory endurance in response to OCC-walk is unknown. Ischemia enhances the adaptation to endurance training such as increased maximal oxygen uptake (VO₂(max)) and muscle glycogen content. Thus, we investigated the effects of an OCC-walk on cardiorespiratory endurance, anaerobic power, and muscle strength in elite athletes. College basketball players participated in walk training with (n = 7) and without (n = 5) blood flow occlusion. Five sets of a 3-min walk (4-6 km/h at 5% grade) and a 1-min rest between the walks were performed twice a day, 6 days a week for 2 weeks. Two-way ANOVA with repeated measures (groups x time) was utilized (P < 0.05). Interactions were found in VO₂(max) (P = 0.011) and maximal minute ventilation (VE(max); P = 0.019). VO₂(max) (11.6%) and VE(max) (10.6%) were increased following the OCC-walk. For the cardiovascular adaptations of the OCC-walk, hemodynamic parameters such as stroke volume (SV) and heart rate (HR) at rest and during OCC-walk were compared between the first and the last OCC-walk sessions. Although no change in hemodynamics was found at rest, during the last OCC-walk session SV was increased in all five sets (21.4%) and HR was decreased in the third (12.3%) and fifth (15.0%) sets. With anaerobic power an interaction was found in anaerobic capacity (P = 0.038) but not in peak power. Anaerobic capacity (2.5%) was increased following the OCC-walk. No interaction was found in muscle strength. In conclusion, the 2-week OCC-walk significantly increases VO₂(max) and VE(max) in athletes. The OCC-walk training might be used in the rehabilitation for athletes who intend to maintain or improve endurance.

Dietary supplement with a combination of Rhodiola crenulata and Ginkgo biloba enhances the endurance performance in healthy volunteers

To determine whether the ingestion of a herbal supplement called Rhodiola-Gingko Capsule (RGC) would enhance the endurance performance of healthy volunteers and change relevant hormones in a favorable manner. Seventy healthy male volunteers (age ranges from 18 to 22 years old) were randomly assigned to RGC group (35 cases, each capsule containing 270 mg herbal extracts, 4 capsules per day) or placebo group (35 cases, equivalent placebo preparation) for 7 weeks using computer produced digital random method. The endurance performance, serum testosterone and cortisol levels were measured at the baseline and the endpoint. Sixty-seven subjects (34 in the RGC group and 33 in the placebo group) completed a 7-week treatment. The RGC group displayed a significantly greater baseline-to endpoint increase in maximal oxygen uptake (VO(2max)) than placebo group in both absolute (P=0.020) and relative values (P=0.023). At the endpoint, the serum cortisol level was unchanged in the RGC group compared with the baseline, but it was significantly elevated in the placebo group (P<0.05). The endpoint ratio of testosterone to cortisol, a surrogate for overtraining and fatigue in endurance exercises, was also indifferent compared with the baseline in the RGC group, but significantly decreased in the placebo group (P<0.05). The combined herbal supplement of Rhodiola and Gingko could improve the endurance performance by increasing oxygen consumption and protecting against fatigue.

Increased Aerobic Fitness In Late Pregnancy Predicts Shorter Labor In Nulliparous, But Not Multiparous, Women.

Similar to the general population, the level of physical activity is inadequate among pregnant women. The ensuing state of over-nutrition as a consequence of physical inactivity prolongs labor and thereby the risk of several obstetrical implications including fetal asphyxia, infections and obstetrical fistulas. Well-trained women who maintain physical exercise during pregnancy have shorter labor compared to those who stop training before the end of the first trimester. Much less is known about whether aerobic fitness in a general cohort of pregnant women is related to duration of labor. PURPOSE: We wanted to investigate the effect of aerobic fitness on duration of labor among nulli- and multiparous women using two valid indicators, namely measurement of maximal oxygen uptake and calculation of anaerobic threshold. METHODS: Maximal oxygen uptake and anaerobic threshold were measured in 59 nulli- and 51 multiparous women at 36 weeks of gestation. Duration of labor was defined as the time between three cm cervical dilation with regular uterine contractions and delivery. Unpaired sample t-test, Pearson correlation test and multiple linear regression were used for statistical analysis. RESULTS: Maximal oxygen uptake was similar for both groups (mean 2.1 L/min). Labor was as expected longer (p < 0.001) in the nulliparous compared to the multiparous women: 9.3±5.0 and 4.5±2.3 hours, respectively. For nulliparous women who started labor spontaneously, duration of labor was inversely associated with maximal oxygen uptake (p=0.03). This indicates that for an increase in maximal oxygen uptake of 0.1 L/min, labor would be shortened by on average 33 minutes. In contrast, in multiparous women who started labor spontaneously, anaerobic threshold was positively associated with duration of labor (p=0.002). This indicates that an increase in anaerobic threshold of 0.1 L/min would prolong labor by on average 22 minutes. Conclusion: Increased maximal oxygen uptake is associated with shorter labor in nulliparous women who start labor spontaneously, whereas increased anaerobic threshold is associated with prolonged labor in multiparous women.

Asthma bronchiale und Sport - Risiko und Chance

Not only asthmatic subjects can suffer from exercise induced airway obstruction, but also healthy persons. Symptoms are various. Exercise induced asthma is a nonspecific airway - reaction of asthmatic patients after a period of exercise, especially a reaction on hyperventilation. This can prevent asthmatic subjects from playing sports or attempting to keep fit. In a Danish co-twin control study physical activity was identified as a risk factor for asthma. Becker et al. presented a report of a 7-year experience with regard to asthma deaths during sports. The subjects who had fatal asthma exacerbations were usually between the ages of 10 and 21 years. Most of them had no long-term control medications. In a review of 13 randomised controlled studies of asthmatic subjects undertaking physical training Ram et al. concluded that physical training improved cardiopulmonary fitness as measured by an increase in maximum oxygen uptake and maximum expiratory ventilation. A number of studies in the effects of physical conditioning on children and adolescents with asthma have reported some reductions in hospitalisations, wheeze frequency, school absenteeism, doctor consultations and medication usage. Guidelines recommend physical training in the treatment of asthma. To take the chances of sport it is necessary to explain the risks to asthmatic subjects. It must be sure that patients with asthma are properly medicated and rescue medication must be immediately available during any sports activity.

The Influence of Sodium Phosphate Supplementation on VO2max, Serum 2,3-diphosphoglycerate Level and Heart Rate in Off-road Cyclists

The Influence of Sodium Phosphate Supplementation on VO2max, Serum 2,3-diphosphoglycerate Level and Heart Rate in Off-road Cyclists The main objective of the work was to evaluate the influence of a six day supplementation with sodium phosphate on circulatory and pulmonary variables, the level of 2,3-diphosphoglycerate (2,3-DPG) and the concentration of inorganic phosphates in blood serum of elite off-road cyclists. The research material included 19 cyclists which were randomly divided into a experimental group, supplemented with sodium phosphate and a control group receiving a placebo The subjects in the experimental group ingested sodium diphosphate in a dose of 50mg/kg of fat free mass per day. The supplement was ingested in even doses, four times per day. The control group received 4g of glucose in gelatin capsules (500mg), which were also divided into 4 even portions. During the experiment a significant (p&lt;0.05) increase in maximal oxygen uptake was observed (VO2max), maximal minute ventilation (VEmax), as well as oxygen pulse (O2/HR). Also a significant decrease in resting and maximal exercise heart rate occurred. This was also true for each exercise load. A significant (p&lt;0.05) increase in the serum concentration of non-organic phosphates (P) was observed which was accompanied by a decrease in serum calcium (Ca) concentration. The changes in the resting and post exercise concentration of 2,3-DPG were non significant, yet the supplementation procedure showed a tendency for increased level of this variable.

The role of physical activity in the management of impaired glucose tolerance: a systematic review

Although physical activity is widely reported to reduce the risk of type 2 diabetes in individuals with prediabetes, few studies have examined this issue independently of other lifestyle modifications. The aim of this review is to conduct a systematic review of controlled trials to determine the independent effect of exercise on glucose levels and risk of type 2 diabetes in people with prediabetes (IGT and/or IFG). A detailed search of MEDLINE (1966–2006) and EMBASE (1980–2006) found 279 potentially relevant studies, eight of which met the inclusion criteria for this review. All eight studies were controlled trials in individuals with impaired glucose tolerance. Seven studies used a multi-component lifestyle intervention that included exercise, diet and weight loss goals and one used a structured exercise training intervention. Four studies used the incidence of diabetes over the course of the study as an outcome variable and four relied on 2-h plasma glucose as an outcome measure. In the four studies that measured the incidence of diabetes as an outcome, the risk of diabetes was reduced by approximately 50% (range 42–63%); as these studies reported only small changes in physical activity levels, the reduced risk of diabetes is likely to be attributable to factors other than physical activity. In the remaining four studies, only one reported significant improvements in 2-h plasma glucose even though all but one reported small to moderate increases in maximal oxygen uptake. These results indicate that the contribution of physical activity independent of dietary or weight loss changes to the prevention of type 2 diabetes in people with prediabetes is equivocal.

Concurrent Strength and Endurance Training

Strength and endurance training produce widely diversified adaptations, with little overlap between them. Strength training typically results in increases in muscle mass and muscle strength. In contrast, endurance training induces increases in maximal oxygen uptake and metabolic adaptations that lead to an increased exercise capacity. In many sports, a combination of strength and endurance training is required to improve performance, but in some situations when strength and endurance training are performed simultaneously, a potential interference in strength development takes place, making such a combination seemingly incompatible. The phenomenon of concurrent training, or simultaneously training for strength and endurance, was first described in the scientific literature in 1980 by Robert C. Hickson, and although work that followed provided evidence for and against it, the interference effect seems to hold true in specific situations. At the molecular level, there seems to be an explanation for the interference of strength development during concurrent training; it is now clear that different forms of exercise induce antagonistic intracellular signaling mechanisms that, in turn, could have a negative impact on the muscle's adaptive response to this particular form of training. That is, activation of AMPK by endurance exercise may inhibit signaling to the protein-synthesis machinery by inhibiting the activity of mTOR and its downstream targets. The purpose of this review is to briefly describe the problem of concurrent strength and endurance training and to examine new data highlighting potential molecular mechanisms that may help explain the inhibition of strength development when strength and endurance training are performed simultaneously.

Exercise and Lymphocyte Activation following Chemotherapy for Breast Cancer

To determine whether exercise training would increase lymphocyte activation in patients with breast cancer following chemotherapy. Activation was determined by the presence of CD4(+)CD69(+) T-helper lymphocytes, mitogen-induced proliferation, and levels of cytokines produced by mitogen-stimulated lymphocytes and in the patients' plasma. Patients with breast cancer (N = 28) who participated in a 6-month exercise program were compared with patients (N = 21) who did not exercise. Following chemotherapy, and 3 and 6 months later, patients underwent fitness evaluations and had blood drawn. The exercise program consisted of resistance training and aerobic activity at 60-75% functional capacity three times a week with a personal trainer. Immunochemistry and flow cytometry were used to measure the number of CD4(+)CD69(+) blood lymphocytes. Whole blood was stimulated with concanavalin A (ConA), phytohemagglutin (PHA), or pokeweed mitogen (PWM) to determine proliferation potential. Enzyme-linked immunosorbent assays (ELISA) were used to determine the concentration of interferon-gamma (IFN-gamma) and interleukin-6 (IL-6) in the culture medium of mitogen-stimulated lymphocytes as well as the plasma concentrations of IL-6, soluble IL-6 receptor, soluble gp130, and IFN-gamma. Analysis of groups across time was done using the Wilcoxon signed rank test, and comparisons of groups were done using the Mann-Whitney U test. The exercising patients showed increases in maximal oxygen uptake and upper body strength. This group also showed a greater percentage of CD4(+)CD69(+) cells and a greater level of tritiated thymidine incorporation (DNA synthesis) when stimulated with ConA, PHA, and PWM at the end of the intervention. Plasma and mitogen-stimulated IL-6 and IFN-gamma production were similar in both groups. Exercise may improve immune function by increasing lymphocyte activation in patients with breast cancer following treatment.

VENTILATORY SUPPORT DURING TRAINING IMPROVES TRAINING BENEFIT IN SEVERE CHRONIC AIRWAY OBSTRUCTION

BACKGROUND One mechanism that may limit training effect in chronic obstructive pulmonary disease is the ventilatory limitation and associated dyspnea. OBJECTIVES To minimize ventilatory limitation during training of patients with severe COPD by applying bi-level positive pressure ventilation during training in order to augment training intensity (and effect). METHODS The study group comprised 19 patients (18 males, 1 female) with a mean age of 64 +/- 9 years. Mean forced expiratory volume in 1 second was 32 +/- 4% of predicted, and all were ventilatory-limited (exercise breathing reserve 3 +/- 9 L/min, normal > 15 L/min). The patients were randomized: 9 were assigned to training with BiPAP and 10 to standard training. All were trained on a treadmill for 2 months, twice a week, 45 minutes each time, at maximal tolerated load. Incremental maximal unsupported exercise test was performed before and at the end of the training period. RESULTS BiPAP resulted in an increment of 94 +/- 53% in training speed during these 2 months, as compared to 41 +/- 19% increment in the control group (P < 0.005). Training with BiPAP yielded an average increase in maximal oxygen uptake of 23 +/- 16% (P < 0.005), anaerobic threshold of 11 +/- 12% (P < 0.05) and peak O2 pulse of 20 +/- 19% (P < 0.05), while peak exercise lactate concentration was not higher after training. Interestingly, in the BiPAP group, peak exercise ventilation was also 17 +/- 20% higher after training (P < 0.05). Furthermore, contrary to our expectation, at any given work rate, ventilation (and tidal volume) in the BiPAP group was higher in the post-training test as compared to the pre-training test, and the end tidal partial pressure of CO2 at 55 watts was lower, 40 +/- 4 and 38 +/- 4 mmHg respectively (P < 0.05). No improvement in exercise capacity was observed after this short training period in the control group. CONCLUSION Pressure-supported ventilation during training is feasible in patients with severe COPD and it augments the training effect. The improved exercise tolerance was associated with higher ventilatory response and therefore lower P(ET)CO2 at equal work rates after training.

Changes Of Health-related Quality Of Life As Related To Changes In Vo2max In Exercise Program

PURPOSE Aerobic exercise is known to induce subjective improvement in the quality of life, whereas one of the most commonly observed objective effects of aerobic exercise is the increase in maximal oxygen uptake (VO2max). Will these two subjective and objective variables change in parallel when middle-aged or older people exercise? The purpose of this study is to assess the relation between the changes of health-related quality of life (HRQOL) and the changes in VO2max in an exercise program. METHODS This is a subgroup analysis of 107 men and 142 women (mean age 67.6±6.4 years) in the intervention group who participated in a 6-month exercise program at fitness clubs (The Sapporo Fitness Club Trial, reported elsewhere). They were relatively inactive and overweight with two or more of the following cardiovascular risk factors: hypertension, hyperlipidemia and impaired glucose intolerance. The subjects exercised on a stationary bicycle at fitness clubs 2–4 times a week for 6 months. The VO2max was estimated from the time on the bicycle during symptom-limited maximal exercise test. Calibration with the actual measurement of VO2max had been prior to the study. The Medical Outcome Study Short-Form 36 Health Status Survey (SF-36) was used as a measure of HRQOL. The score was treated as a continuous variable. Univariate correlation analysis was performed using Spearman's correlation coefficient. The multiple regression analysis was used with changes in each SF-36 score as the dependent variable and with the changes in VO2max, baseline VO2max, baseline SF-36 scores, baseline BMI, age and gender as the independent variable. RESULTS After exercise program, BMI decreased from 26.4 ±2.0 to 25.7 ± 1.9 (p < 0.001) and VO2max (ml/kg/min) increased from 20.7 ±3.6 to 23.1 ± 4.4 (p < 0.001). Scores of 3 domains of SF-36 significantly improved; the mean General Health increased from 64.3 ± 16.2 to 69.5 ± 15.9 (p < 0.001), Vitality from 70.5 ± 19.8 to 74.7 ± 18.1 (p < 0.001), and Mental Health from 79.6 ± 16.6 to 82.0 ± 16.0 (p=0.03). There were significant or nearly significant univariate correlations between changes in VO2max and Physical Functioning (p=0.02), Role-physical (p=0.01), Role-emotional (p=0.02), Bodily Pain (p=0.10) and General Health (p=0.11). The multiple regression analysis showed that changes in VO2max was a significantly independent determinant of Physical Functioning (p < 0.001), Role-physical (p=0.001) Bodily Pain (p < 0.001), General Health (p=0.03) Vitality (p=0.02) and Role-emotional (p=0.001). CONCLUSION The improvement in many domains of health-related quality of life (SF-36) was associated with an increase in VO2max induced by aerobic exercise.