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HIGHER CARDIORESPIRATORY FITNESS ATTENUATES ARTERIAL STIFFENING ASSOCIATED WITH THE ESTROGEN RECEPTOR-BETA POLYMORPHISM IN HEALTHY WOMEN
low-cardiorespiratory fitness (Low-fit) groups based on the median value of peak oxygen uptake in each gender and decade. Results:
High-fit subjects had lower baPWV value than in Low-fit subjects (High-fit; 1225±224, Low-fit; 1292±284 cm/sec, mean±SD, p0.05). The baPWV value of individuals with the TT genotype of ESR2 was significantly higher than those with the TG and GG genotypes (GG;
1244±267, GT; 1273±264, TT; 1328±305 cm/sec). In the Low-fit subjects, baPWV value was significantly higher in individual with TT genotype (1387±364 cm/sec) than in individuals with the GT (1293±280 cm/sec) and GG (1255±246 cm/sec) genotypes. However, there were no such differences in High-fit subjects (GG; 1234±285, GT; 1252±247, TT; 1256±235 cm/sec). Conclusion: These results revealed that the higher cardiorespiratory fitness may attenuate the change in arterial stiffness that is associated with ESR2 gene polymorphism (rs1271572) in the healthy Japanese women. References: Meyer MR, et al., (2009) Cardiovascular research, 83, 605-610. Villablanca AC, et al. (2009) J Cardiovasc Transl Res, 2, 289-99. Grants: Supported by KAKENHI of the Japan Ministry of Education, Culture, Sports, Science and Technology (MI, MM).
ASSESSMENT OF HEART RATE, PULMONARY AND MUSCULAR V’O2-KINETICS OF UPPER AND LOWER BODY EXERCISE
DURING DYNAMIC MODERATE WORK RATE CHANGESDrescher, U., Loosen, D., Baak, B., Essfeld, D., Hoffmann, U.
German Sport University Cologne Introduction During dynamic work rate changes the kinetics of heart rate and pulmonary V’O2 can be measured by ECG and gas exchange easily. Muscular V’O2 kinetics can be non-invasively estimated by using time-series analysis in combination with a physiological model, comprising the time delay and the distortive effects of the cardio-dynamic phases between muscular and pulmonary level (Hoffmann et. al., in press). Using the mentioned non-invasive approach, we compared the kinetics of upper (Up: arms/torso) and lower body (Lo: legs) exercise for heart rate (HR), pulmonary (V’O2pulm) and in particular for calculated muscular oxygen uptake (V’O2musc).
Methods 11 male volunteers (age: 24 ± 2 years; height: 184 ± 8 cm; weight: 79 ± 7 kg; relV’O2peak(Up): 37.8 ± 5.0 ml•min-1•kg-1; relV’O2peak(Lo):
56.1 ± 7.4 ml•min-1•kg-1) were subjected to pseudo random binary work rate (WR) changes on a leg cycle ergometer (30 W, 80 W) and an arm cranking exercise device (20 W, 50 W). HR was measured beat-to-beat by ECG, V’O2pulm was determined breath-by-breath, and V’O2musc was estimated by the method of Hoffmann et al. (in press) for Up and Lo. Given a linear, time-invariant, first order system the peak of the cross correlation function (CCF) of WR and a second parameter (e. g. HR, V’O2pulm, V’O2musc) indicates the kinetic responses of this parameter (Hpeak, Ppeak, Mpeak). Higher peaks denote faster system responses. Accordingly, for Up and Lo the kinetic responses for HR (Up_Hpeak, Lo_Hpeak), V’O2pulm (Up_Ppeak, Lo_Ppeak) and V’O2musc (Up_Mpeak, Lo_Mpeak) were calculated.
Differences between the kinetic responses were statistically analyzed applying a two-way ANOVA (parameter x exercise mode) for repeated measurements. Results Significant differences were found between Up_Mpeak (0.341 ± 0.062) and Lo_Mpeak (0.414 ± 0.046;
p=.018; n=11). In addition, there were no significant differences between Up_Hpeak (0.465 ± 0.183) and Lo_Hpeak (0.457 ± 0.075;
p=.895; n=11), as well as between Up_Ppeak (0.312 ± 0.090) and Lo_Ppeak (0.351 ± 0.072; p=.316; n=11). Discussion It can be speculated that there could be differences between upper and lower muscular V’O2 kinetics due to different characteristics of the specific upper and lower body musculature from daily activities. Furthermore, the influence of the individual training status, muscle fiber composition, and enzyme activity, remain to be clarified. The study was funded by the DLR (Deutsches Zentrum für Luft- und Raumfahrt), Germany (FKZ 50WB0726). References Hoffmann U, Drescher U, Benson AP, Rossiter HB, Essfeld D (in press).
SYMMETRIC CARDIOVASCULAR DYNAMICS GENERATE ASYMMETRIC RESPIRATORY V’O2 RESPONSES TO ON- AND
OFF-STEP CHANGES IN WORKLOADHoffmann, U., Drescher, U., Mookerjee, S., Eßfeld, D.
German Sport University Cologne Introduction Muscular V’O2 kinetics (V’O2musc) are frequently estimated on the basis of respiratory V‘O2 (V’O2resp) responses to step changes in workload. A typical approach to account for the distorting effects of cardiac output (CO) dynamics and venous return is to discard the initial response of about 20 s (“cardiogenic phase”) before data fitting. Methods In this study we investigated, by means of a mathematical model, the influence of CO dynamics, muscle perfusion, venous volume and venous volume distribution on respiratory V’O2 as well as the effect of discarding the first 20 s of V’O2resp on the quality of V’O2musc estimation. Results The results show marked asymmetries between on- and off V’O2resp kinetics and substantial errors in V’O2musc estimates in particular for the off-kinetics. Discarding cardiogenic phases only partly compensates for the distortion of muscular V’O2 generated by the transport through the venous system. Within the parameter settings chosen, errors in the estimate of V’O2musc time constants were up to 90% for off-kinetics and up to 40% for on-kinetics. Discussion The simulations suggest, that major improvements in estimated muscular V’O2 kinetics can only be obtained if the values of the relevant distorting parameters (muscle perfusion, venous volume and venous volume) are known. These values would allow a backward computation of muscular V’O2 dynamics from respiratory V’O2 data. References Barstow TJ and Mole PA. (1987). J Appl Physiol, 63, 2253-2261. Bearden SE and Moffatt RJ. (2001). J Appl Physiol, 90, 2081-2087. Grassi B, Pogliaghi S, Rampichini S, Quaresima V, Ferrari M, Marconi C, and Cerretelli P. (2003). J Appl Physiol, 95, 149-158. Murias JM, Kowalchuk JM, and Paterson DH. (2010). J Appl Physiol, 108, 913-922. Rossiter HB, Ward SA, Kowalchuk JM, Howe FA, Griffiths JR, and Whipp BJ. (2002). J Physiol, 541, 991-1002.
GROUND’S SLOPE AFFECTS THE VENTILATORY EFFICIENCY IN SKYRUNNERS DURING A RACE SIMULATION AT ALTITUDEMandolesi, G.1, Mossuto, G.1, Spiridonova, M.1, Telli, R.2, Marchetti, A.3, Rosa, S.3, Roi, G.S.4, Cogo, A.1 1: University of Ferrara (Italy), 2: University of Milano (Italy), 3: University of Bologna (Italy), 4: Isokinetic (Bologna, Italy) Introduction Skyrunning is the discipline of running in the mountains above 2000 m where the slope can exceeds 30%. During races at altitude the ventilatory request increases due to the combined effect of exercise and hypoxia. It is well known that a deeper and lower ventilation (VE) is more efficient in terms of gas exchanges. We aimed to analyse the ventilation, the thoraco-abdominal coordination and the oxygen saturation (SpO2) in skyrunners during a race simulation. Methods 14 athletes (12M; age 34-60) run from 2030m to 2804m wearing an inductive pletismography system (Lifeshirt) equipped with a pulse-oximeter and GPS (Garmin). We evaluated ventilation (VE), tidal volume (VT), ventilatory pattern (VE/ VT) and phase angle (PhA), index of thoraco-abdominal coordination. Results Subjects run 6.2 kilometers, mean speed 1.6m/s. Values at rest and during the ascent are respectively: SpO2 (%) (94.8±1.2; 85.2±3.2) VE (L/min) (20.3±4.3;
128.6±29.3), VE/VT (22.4±3.9; 52.3±8.4). The relationship between the slope (S) and PhA is represented by a quadratic curve. As S increases 30% a significant increase in PhA is observed (p0.01), index of worsening thoraco-abdominal coordination. The increase in PhA is significantly related to an increase in VE/VT (r=0.4*) which in turn affects SpO2. In fact the correlation between VE/VT and SpO2 is highly significant (r = - 0.69). The low SpO2 is associated to a lower race speed (r= 0.33*). *p0.01 Discussion Our data evidence that in skyrunners the slope of ground negatively influences the thoraco-abdominal coordination, mostly when slope is 30%. The increase in slope is also related to a decrease in SpO2 through a change in ventilatory pattern toward a less efficient breath. These factors negatively influence the speed performance. References Casaburi R, Porszasz J, Burns MR, Carithers ER, Chang RS, Cooper CB. (1997). Am J Respir Crit Care Med, 155, 1541-1551. Bernardi L, Spadacini G, Bellwon J, Hajric R, Roskamm H, Frey AW. (1998). Lancet, 351, 1308-1311. Do not insert authors here
EFFECTS OF VARYING RAMP PROTOCOLS ON PEAK POWER AND MAXIMAL OXYGEN CONSUMPTION: A VALIDATIONOF MORTON’S MODEL Ferretti, G., Sivieri, A., Moia, C., Perini, R., Adami, A.
University of Brescia, IT, and University of Geneva, CH Introduction In ramp protocols, the peak power attained at the end of the test (w’peak) does not correspond to the w’max of a classical Astrand-type test. On this basis, Morton (2011) proposed a model of w’peak that included critical power (CP) and anaerobic capacity as constants, and the mean ramp slope as variable. He validated his model using experimental data from a previous study (Morton et al., 1997), with continuous linear ramp increments. Yet most ramp tests foresee discrete step ramp increments, in which power is increased by a given amount at a given fixed time which may vary from 15 to 300 s. The aim of this study was to test Morton’s model of w’peak in ramp tests, with invariant step increment and increasing step duration. Methods 16 men performed six ramp tests with 25 W increments up to exhaustion. Step duration was: 15, 30, 60, 90, 120 and 180 s. V’O2max and w’peak were identified as the highest values reached during each test. An Astrand-type test with 50 W increments, 5-min duration steps, 6-min recovery between steps, was also performed,
in which V’O2max and w’max were established from plateau in the V’O2 versus power relationship. V’O2 and ventilatory variables were measured by metabolic cart. Lactate and heart rate (HR) were also measured. The results were fitted into Morton’s model. Results V’O2max was the same in all tests. In contrast, w’peak was lower the longer the step duration, with differences being significant among all step durations. All w’peak obtained in the various ramp tests were significantly different from the w’max of the Astrand-type test. At the end of the test, no differences were observed for HR, except for the two shortest protocols (15 and 30s ramps), during which a significantly lower HR was reached compared with the longest ramp test. No differences were found for the peak [La]b values among the various ramp tests. When w’peak was analysed within Morton’s model, an excellent fitting was found, yielding mean CP equal to 198.08 ± 37.46 W and anaerobic capacity equal to 16.82 ± 5.69 kJ. Further developments of Morton’s model provided a univocal relation between CP and w’max. Discussion Present validation of Morton’s model authorizes estimating CP and w’max from any type of ramp test, provided w’peak and ramp slope are known. Thus, there is no further need of establishing lactate threshold or performing long protocols like the Astrand-type when training powers are to be set. References Morton RH. (2011). J Sport Sci 29: 307-9. Morton RH, Green S, Bishop D, Jekins DG (1997). Med Sci Sports Exerc 29: 833-6.