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Effect of carbohydrate availability on time to exhaustion in exercise performed at two different intensities
Lima-Silva, A.E.;De-Oliveira, F.R.;Nakamura, F.Y.;Gevaerd, M.S.;
Brazilian Journal of Medical and Biological Research , 2009, DOI: 10.1590/S0100-879X2009000500002
Abstract: this study examined the effects of pre-exercise carbohydrate availability on the time to exhaustion for moderate and heavy exercise. seven men participated in a randomized order in two diet and exercise regimens each lasting 3 days with a 1-week interval for washout. the tests were performed at 50% of the difference between the first (lt1) and second (lt2) lactate breakpoint for moderate exercise (below lt2) and at 25% of the difference between the maximal load and lt2 for heavy exercise (above lt2) until exhaustion. forty-eight hours before each experimental session, subjects performed a 90-min cycling exercise followed by 5-min rest periods and a subsequent 1-min cycling bout at 125% vo2max/1-min rest periods until exhaustion to deplete muscle glycogen. a diet providing 10% (cholow) or 65% (chomod) energy as carbohydrates was consumed for 2 days until the day of the experimental test. in the exercise below lt2, time to exhaustion did not differ between the chomod and the cholow diets (57.22 ± 24.24 vs 57.16 ± 25.24 min). in the exercise above lt2, time to exhaustion decreased significantly from 23.16 ± 8.76 min on the chomod diet to 18.30 ± 5.86 min on the cholow diet (p < 0.05). the rate of carbohydrate oxidation, respiratory exchange ratio and blood lactate concentration were reduced for cholow only during exercise above lt2. these results suggest that muscle glycogen depletion followed by a period of a low carbohydrate diet impairs high-intensity exercise performance.
Blood glucose responses of type-2 diabetics during and after exercise performed at intensities above and below anaerobic threshold
Wolysson C. Hiyane,Maysa Vieira de Sousa,Sérgio R. Moreira,Gabriele do Valle
Revista Brasileira de Cineantropometria e Desempenho Humano , 2008,
Abstract: With the objective of analyzing the blood glucose responses during and after exercise performed at 90 and 110% of anaerobic threshold (AT), 10 type-2 diabetes patients (56.9±11.2years; 80.3±14.4kg) performed an incremental test (IT) on a cycle ergometer. After an initial IT to identify AT, the volunteers participated in three experimental sessions on three different days: 20 minutes’ of cycling at either 90 or 110% of AT, and a control session (CON). Blood glucose was measured at rest, and at the 10th and 20th minutes of exercise or control condition, as well as every 15 minutes during a 2-hour postexercise recovery period (Rec). One-way ANOVA did not detect signifi cant differences in blood glucose levels between the sessions at 90 and 110% of AT. Compared to CON, a signifi cant decrease was observed at the 20th minute of exercise, and at the 15th and 60th minutes of Rec from the 90% AT session. Signifi cant reductions were also observed at the 10th and 20th minutes of exercise and at the 15th, 30th, 45th, 60th and 90th minutes of Rec from the session at 110% AT. Exercise performed at the higher intensity (110% AT) resulted in a tendency of a more pronounced and prolonged hypoglycemic effect during and after exercise, and may be an alternative intensity for glycemic control in type 2 diabetics who do not have cardiovascular complications or other contraindications to exercising at intensities above the AT. Resumo Com o propósito de analisar a resposta da glicose sanguínea durante e após exercício a 90 e 110% do limiar anaeróbio (LA), 10 voluntários diabéticos tipo 2 (56,9 ± 11,2 anos; 80,3 ± 14,4 kg), realizaram um teste incremental (TI) em cicloerg metro. Após a realiza o do TI para identifi ca o do LA, os voluntários realizaram 3 sess es experimentais em dias distintos: 20 minutos em bicicleta ergométrica a 90 e 110% LA e uma sess o controle (CON). A glicemia foi mensurada no repouso, aos 10 e 20 min de exercício ou na situa o controle, bem como a cada 15 minutos durante 2 horas do período de recupera o pós-exercício (Rec) e CON. ANOVA n o identificou diferen as significantes nas concentra es de glicose sanguínea durante e após as sess es de 90 e 110% LA. Comparado ao controle, redu o signifi cativa da glicemia foi observada aos 20 min de exercício (-41 + 15 mg.dl-1), aos 15 min (-48 + 21 mg.dl-1) e 60 min da Rec pós sess o a 90% LA, sendo também observada diminui o signifi cativa da glicemia aos 10 e 20 min do exercício e aos 15, 30, 45, 60 e 90 min da Rec após sess o de 110% LA. O exercício de maior intensidade (110% LA) resultou em tendênci
Post-exercise changes in blood pressure, heart rate and rate pressure product at different exercise intensities in normotensive humans
Forjaz, C.L.M.;Matsudaira, Y.;Rodrigues, F.B.;Nunes, N.;Negr?o, C.E.;
Brazilian Journal of Medical and Biological Research , 1998, DOI: 10.1590/S0100-879X1998001000003
Abstract: to evaluate the effect of exercise intensity on post-exercise cardiovascular responses, 12 young normotensive subjects performed in a randomized order three cycle ergometer exercise bouts of 45 min at 30, 50 and 80% of vo2peak, and 12 subjects rested for 45 min in a non-exercise control trial. blood pressure (bp) and heart rate (hr) were measured for 20 min prior to exercise (baseline) and at intervals of 5 to 30 (r5-30), 35 to 60 (r35-60) and 65 to 90 (r65-90) min after exercise. systolic, mean, and diastolic bp after exercise were significantly lower than baseline, and there was no difference between the three exercise intensities. after exercise at 30% of vo2peak, hr was significantly decreased at r35-60 and r65-90. in contrast, after exercise at 50 and 80% of vo2peak, hr was significantly increased at r5-30 and r35-60, respectively. exercise at 30% of vo2peak significantly decreased rate pressure (rp) product (rp = hr x systolic bp) during the entire recovery period (baseline = 7930 ± 314 vs r5-30 = 7150 ± 326, r35-60 = 6794 ± 349, and r65-90 = 6628 ± 311, p<0.05), while exercise at 50% of vo2peak caused no change, and exercise at 80% of vo2peak produced a significant increase at r5-30 (7468 ± 267 vs 9818 ± 366, p<0.05) and no change at r35-60 or r65-90. cardiovascular responses were not altered during the control trial. in conclusion, varying exercise intensity from 30 to 80% of vo2peak in young normotensive humans did not influence the magnitude of post-exercise hypotension. however, in contrast to exercise at 50 and 80% of vo2peak, exercise at 30% of vo2peak decreased post-exercise hr and rp.
Post-exercise changes in blood pressure, heart rate and rate pressure product at different exercise intensities in normotensive humans  [cached]
Forjaz C.L.M.,Matsudaira Y.,Rodrigues F.B.,Nunes N.
Brazilian Journal of Medical and Biological Research , 1998,
Abstract: To evaluate the effect of exercise intensity on post-exercise cardiovascular responses, 12 young normotensive subjects performed in a randomized order three cycle ergometer exercise bouts of 45 min at 30, 50 and 80% of VO2peak, and 12 subjects rested for 45 min in a non-exercise control trial. Blood pressure (BP) and heart rate (HR) were measured for 20 min prior to exercise (baseline) and at intervals of 5 to 30 (R5-30), 35 to 60 (R35-60) and 65 to 90 (R65-90) min after exercise. Systolic, mean, and diastolic BP after exercise were significantly lower than baseline, and there was no difference between the three exercise intensities. After exercise at 30% of VO2peak, HR was significantly decreased at R35-60 and R65-90. In contrast, after exercise at 50 and 80% of VO2peak, HR was significantly increased at R5-30 and R35-60, respectively. Exercise at 30% of VO2peak significantly decreased rate pressure (RP) product (RP = HR x systolic BP) during the entire recovery period (baseline = 7930 ± 314 vs R5-30 = 7150 ± 326, R35-60 = 6794 ± 349, and R65-90 = 6628 ± 311, P<0.05), while exercise at 50% of VO2peak caused no change, and exercise at 80% of VO2peak produced a significant increase at R5-30 (7468 ± 267 vs 9818 ± 366, P<0.05) and no change at R35-60 or R65-90. Cardiovascular responses were not altered during the control trial. In conclusion, varying exercise intensity from 30 to 80% of VO2peak in young normotensive humans did not influence the magnitude of post-exercise hypotension. However, in contrast to exercise at 50 and 80% of VO2peak, exercise at 30% of VO2peak decreased post-exercise HR and RP.
Impaired functional and hemodynamic response to graded exercise testing and its recovery in patients with subclinical hyperthyroidism
Vigário, Patrícia dos Santos;Chachamovitz, Dhi?nah Santini de Oliveira;Teixeira, Patrícia de Fátima dos Santos;Santos, Mauro Augusto dos;Oliveira, Fátima Palha de;Vaisman, Mário;
Arquivos Brasileiros de Endocrinologia & Metabologia , 2011, DOI: 10.1590/S0004-27302011000300005
Abstract: objective: to evaluate the functional and hemodynamic responses during exercise and its recovery in patients with subclinical hyperthyroidism (sch). subjects and methods: a cross-sectional study was carried out with 29 patients on tsh-suppressive therapy with levothyroxine for thyroid carcinoma and 35 euthyroid subjects. all volunteers underwent a cardiopulmonary exercise testing on a treadmill and functional and hemodynamic variables were measured during exercise and its recovery. results: sch patients showed impaired functional response to exercise, marked by lower values for oxygen consumption and exercise duration in addition to premature achievement of the anaerobic threshold. heart-rate and blood pressure recovery immediately after exercise were slower among sch patients when compared to euthyroid subjects. conclusion: sch is associated with impaired functional and hemodynamic responses during exercise and its recovery.
Effect of Maturation on Hemodynamic and Autonomic Control Recovery Following Maximal Running Exercise in Highly Trained Young Soccer Players  [PDF]
Martin Buchheit
Frontiers in Physiology , 2011, DOI: 10.3389/fphys.2011.00069
Abstract: The purpose of this study was to examine the effect of maturation on post-exercise hemodynamic and autonomic responses. Fifty-five highly trained young male soccer players (12–18 years) classified as pre-, circum-, or post-peak height velocity (PHV) performed a graded running test to exhaustion on a treadmill. Before (Pre) and after (5th–10th min, Post) exercise, heart rate (HR), stroke volume (SV), cardiac output (CO), arterial pressure (AP), and total peripheral resistance (TPR) were monitored. Parasympathetic (high frequency [HFRR] of HR variability (HRV) and baroreflex sensitivity [Ln BRS]) and sympathetic activity (low frequency [LFSAP] of systolic AP variability) were estimated. Post-exercise blood lactate [La]b, the HR recovery (HRR) time constant, and parasympathetic reactivation (time-varying HRV analysis) were assessed. In all three groups, exercise resulted in increased HR, CO, AP, and LFSAP (P < 0.001), decreased SV, HFRR, and Ln BRS (all P < 0.001), and no change in TPR (P = 0.98). There was no “maturation × time” interaction for any of the hemodynamic or autonomic variables (all P > 0.22). After exercise, pre-PHV players displayed lower SV, CO, and [La]b, faster HRR and greater parasympathetic reactivation compared with circum- and post-PHV players. Multiple regression analysis showed that lean muscle mass, [La]b, and Pre parasympathetic activity were the strongest predictors of HRR (r2 = 0.62, P < 0.001). While pre-PHV players displayed a faster HRR and greater post-exercise parasympathetic reactivation, maturation had little influence on the hemodynamic and autonomic responses following maximal running exercise. HRR relates to lean muscle mass, blood acidosis, and intrinsic parasympathetic function, with less evident impact of post-exercise autonomic function.
Post-Exercise Hypotension: Comparison Between Different Intensities Of Exercise On A Treadmill And A Cycle Ergometer
Juliana Hott de Fúcio Lizardo,Luciana Kool Modesto,Carmen Sílvia Grubert Campbell,Herbert Gustavo Sim?es
Revista Brasileira de Cineantropometria e Desempenho Humano , 2007,
Abstract: To compare the hypotensive effects of exercise sessions performed on treadmill and cycle ergometer and toverify the infl uence of the intensity of such exercise sessions on post-exercise hypotension (PEH). Ten normotensive malesubjects (24.9 ± 3.9 years; 78.3 ± 9.2 kg; 176.9 ± 4.9 cm) performed 4 exercise sessions on different days: two incrementalexercise sessions on a cycle ergometer and a treadmill running until volitional exhaustion, and two continuous exercisesessions (20 min) on a cycle ergometer and a treadmill at intensities corresponding to 85% of maximal heart rate (max HR)reached during the incremental tests. Systolic (SBP) and diastolic blood pressure (DBP) were measured on resting, at theend of exercises and during the 90 minute post-exercise recovery period. After the incremental and continuous sessions onthe treadmill SBP presented a signifi cant reduction at the 45th and 90th minutes and DBP was reduced throughout the entirepost-exercise recovery period (P < 0.05). Post-exercise SBP hypotension was observed at the 90th min of recovery from theincremental and continuous exercise sessions performed on the cycle ergometer, whereas post-exercise DBP hypotensionwas only observed at the 90th minute of recovery from the continuous submaximal session (p < 0.05). Exercise in the form ofrunning on the treadmill was more effective for inducing PEH than exercise performed on the cycle ergometer. The exerciseintensities studied did not appear to infl uence PEH either after treadmill running or cycle ergometer sessions. RESUMO O estudo teve como objetivo comparar os efeitos hipotensores de sess es de exercícios realizados em esteiraergométrica e cicloerg metro e verifi car a infl uência da intensidade dessas sess es sobre a hipotens o pós-exercício(HPE). Participaram do estudo 10 indivíduos normotensos do sexo masculino (24,9 ± 3,9 anos; 78,3 ± 9,2 kg; 176,9 ± 4,9cm) executaram 4 sess es de exercícios em dias distintos: dois testes incrementais em cicloerg metro e corrida em esteiraergométrica até a exaust o voluntária, e duas sess es de exercício contínuo (20 min) em cicloerg metro e esteira à 85%da freqüência cardíaca máxima (FC máx.) atingida nos testes incrementais. A press o arterial sistólica (PAS) e diastólica(PAD) foram mensuradas em repouso pré-exercício, ao fi nal dos exercícios e durante 90 min de recupera o pós-exercício.Em rela o aos valores de repouso pré-exercício, após as sess es de exercício incremental e contínuo em esteira aPAS se apresentou signifi cativamente reduzida (p < 0,05) aos 45 e 90 min, enquanto a PAD se apresentou dimi
Hypotensive effects of resistance exercises performed at different intensities and same work volumes
Polito, Marcos Doederlein;Sim?o, Roberto;Senna, Gilmar Weber;Farinatti, Paulo de Tarso Veras;
Revista Brasileira de Medicina do Esporte , 2003, DOI: 10.1590/S1517-86922003000200003
Abstract: the aim of this paper was to compare the effects of two sequences of resistance exercises (re), with different intensities but same training volume, on post-exercise blood pressure responses. sixteen young subjects with previous experience in re were evaluated during three non-following days in chest press, legpress, pulley pull down, leg curl, shoulder press, and biceps curl. on the first day, the load associated with six maximal repetitions (6rm) were determined for each exercise. on the second day, three sets of 6rm were performed (seq6), with a two minute interval between the sets. on the last day, the same procedure was repeated, but using 12 repetitions with 50% of 6rm load (seq12). rest bp was measured before the sequences by auscultatory method. post-exercise resting bp was measured each 10 minutes by ambulatory bp monitoring during 60 minutes. the magnitude and duration of bp variability were compared by repeated anova measures followed by tuckey post-hoc test (p < 0.05). a significant reduction in diastolic blood pressure (dbp) was observed in the first 20 minutes after seq12, but not after seq6. seq12 elicited significant decline in systolic blood pressure (sbp), at least during the first 50 minutes after the exercise, while significant reductions were observed in all measures after seq6. there were no significant differences between the absolute values of dbp and sbp after both sequences. in conclusion: a) re had hypotensive effects on blood pressure, mainly sbp; b) the absolute decline of sbp seem not to be influenced by different interactions between workload and number of repetitions; c) higher workloads seem to extend the total time of sbp post-exercise reduction; d) the number of repetitions seems to have more influence on dbp than sbp, but for a short period of time.
Hypotensive effects of resistance exercises performed at different intensities and same work volumes  [cached]
Polito Marcos Doederlein,Sim?o Roberto,Senna Gilmar Weber,Farinatti Paulo de Tarso Veras
Revista Brasileira de Medicina do Esporte , 2003,
Abstract: The aim of this paper was to compare the effects of two sequences of resistance exercises (RE), with different intensities but same training volume, on post-exercise blood pressure responses. Sixteen young subjects with previous experience in RE were evaluated during three non-following days in chest press, legpress, pulley pull down, leg curl, shoulder press, and biceps curl. On the first day, the load associated with six maximal repetitions (6RM) were determined for each exercise. On the second day, three sets of 6RM were performed (SEQ6), with a two minute interval between the sets. On the last day, the same procedure was repeated, but using 12 repetitions with 50% of 6RM load (SEQ12). Rest BP was measured before the sequences by auscultatory method. Post-exercise resting BP was measured each 10 minutes by ambulatory BP monitoring during 60 minutes. The magnitude and duration of BP variability were compared by repeated ANOVA measures followed by Tuckey post-hoc test (p < 0.05). A significant reduction in diastolic blood pressure (DBP) was observed in the first 20 minutes after SEQ12, but not after SEQ6. SEQ12 elicited significant decline in systolic blood pressure (SBP), at least during the first 50 minutes after the exercise, while significant reductions were observed in all measures after SEQ6. There were no significant differences between the absolute values of DBP and SBP after both sequences. In conclusion: a) RE had hypotensive effects on blood pressure, mainly SBP; b) the absolute decline of SBP seem not to be influenced by different interactions between workload and number of repetitions; c) higher workloads seem to extend the total time of SBP post-exercise reduction; d) the number of repetitions seems to have more influence on DBP than SBP, but for a short period of time.
Comparison of Different Confidence Intervals of Intensities for an Open Queueing Network with Feedback  [PDF]
Vinayak Kawaduji Gedam, Suresh Bajirao Pathare
American Journal of Operations Research (AJOR) , 2013, DOI: 10.4236/ajor.2013.32028
Abstract:

In this paper we propose a consistent and asymptotically normal estimator (CAN) of intensities ρ1 , ρ2 for a queueing network with feedback (in which a job may return to previously visited nodes) with distribution-free inter-arrival and service times. Using this estimator and its estimated variance, some 100(1-α)% asymptotic confidence intervals of intensities are constructed. Also bootstrap approaches such as Standard bootstrap, Bayesian bootstrap, Percentile bootstrap and Bias-corrected and accelerated bootstrap are also applied to develop the confidence intervals of intensities. A comparative analysis is conducted to demonstrate performances of the confidence intervals of intensities for a queueing network with short run data.

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