Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 5 de 5
Mais filtros

Base de dados
Intervalo de ano de publicação
J Appl Physiol (1985) ; 127(3): 806-815, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31268828


The manipulation of resistance training (RT) variables is used among athletes, recreational exercisers, and compromised populations (e.g., elderly) attempting to potentiate muscle hypertrophy. However, it is unknown whether an individual's inherent predisposition dictates the RT-induced muscle hypertrophic response. Resistance-trained young [26 (3) y] men (n = 20) performed 8 wk unilateral RT (2 times/wk), with 1 leg randomly assigned to a standard progressive RT [control (CON)] and the contralateral leg to a variable RT (VAR; modulating exercise load, volume, contraction type, and interset rest interval). The VAR leg completed all 4 RT variations every 2 wk. Bilateral vastus lateralis cross-sectional area (CSA) was measured, pre- and post-RT and acute integrated myofibrillar protein synthesis (MyoPS) rates were assessed at rest and over 48 h following the final RT session. Muscle CSA increase was similar between CON and VAR (P > 0.05), despite higher total training volume (TTV) in VAR (P < 0.05). The 0-48-h integrated MyoPS increase postexercise was slightly greater for VAR than CON (P < 0.05). All participants were considered "responders" to RT, although none benefited to a greater extent from a specific protocol. Between-subjects variability (MyoPS, 3.30%; CSA, 37.8%) was 40-fold greater than the intrasubject (between legs) variability (MyoPS, 0.08%; CSA, 0.9%). The higher TTV and greater MyoPS response in VAR did not translate to a greater muscle hypertrophic response. Manipulating common RT variables elicited similar muscle hypertrophy than a standard progressive RT program in trained young men. Intrinsic individual factors are key determinants of the MyoPS and change in muscle CSA compared with extrinsic manipulation of common RT variables.NEW & NOTEWORTHY Systematically manipulating resistance training (RT) variables during RT augments the stimulation of myofibrillar protein synthesis (MyoPS) and training volume but fails to potentiate muscle hypertrophy compared with a standard progressive RT. Any modest further MyoPS increase and higher training volumes do not reflect in a greater hypertrophic response. Between-subject variability was 40-fold greater than the variability promoted by extrinsic manipulation of RT variables, indicating that individual intrinsic factors are stronger determinants of the hypertrophic response.

J Physiol ; 594(18): 5209-22, 2016 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-27219125


KEY POINTS: Skeletal muscle hypertrophy is one of the main outcomes from resistance training (RT), but how it is modulated throughout training is still unknown. We show that changes in myofibrillar protein synthesis (MyoPS) after an initial resistance exercise (RE) bout in the first week of RT (T1) were greater than those seen post-RE at the third (T2) and tenth week (T3) of RT, with values being similar at T2 and T3. Muscle damage (Z-band streaming) was the highest during post-RE recovery at T1, lower at T2 and minimal at T3. When muscle damage was the highest, so was the integrated MyoPS (at T1), but neither were related to hypertrophy; however, integrated MyoPS at T2 and T3 were correlated with hypertrophy. We conclude that muscle hypertrophy is the result of accumulated intermittent increases in MyoPS mainly after a progressive attenuation of muscle damage. ABSTRACT: Skeletal muscle hypertrophy is one of the main outcomes of resistance training (RT), but how hypertrophy is modulated and the mechanisms regulating it are still unknown. To investigate how muscle hypertrophy is modulated through RT, we measured day-to-day integrated myofibrillar protein synthesis (MyoPS) using deuterium oxide and assessed muscle damage at the beginning (T1), at 3 weeks (T2) and at 10 weeks of RT (T3). Ten young men (27 (1) years, mean (SEM)) had muscle biopsies (vastus lateralis) taken to measure integrated MyoPS and muscle damage (Z-band streaming and indirect parameters) before, and 24 h and 48 h post resistance exercise (post-RE) at T1, T2 and T3. Fibre cross-sectional area (fCSA) was evaluated using biopsies at T1, T2 and T3. Increases in fCSA were observed only at T3 (P = 0.017). Changes in MyoPS post-RE at T1, T2 and T3 were greater at T1 (P < 0.03) than at T2 and T3 (similar values between T2 and T3). Muscle damage was the highest during post-RE recovery at T1, attenuated at T2 and further attenuated at T3. The change in MyoPS post-RE at both T2 and T3, but not at T1, was strongly correlated (r ≈ 0.9, P < 0.04) with muscle hypertrophy. Initial MyoPS response post-RE in an RT programme is not directed to support muscle hypertrophy, coinciding with the greatest muscle damage. However, integrated MyoPS is quickly 'refined' by 3 weeks of RT, and is related to muscle hypertrophy. We conclude that muscle hypertrophy is the result of accumulated intermittent changes in MyoPS post-RE in RT, which coincides with progressive attenuation of muscle damage.

Hipertrofia/metabolismo , Proteínas Musculares/biossíntese , Doenças Musculares/metabolismo , Miofibrilas/metabolismo , Treinamento de Resistência , Adulto , Humanos , Hipertrofia/fisiopatologia , Masculino , Doenças Musculares/fisiopatologia , Biossíntese de Proteínas
Cell Biochem Biophys ; 74(2): 253-62, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-27126056


We investigated the association between the degree of oxidative modification of LDL particles by non-linear optical response of LDL (Z-scan technique) and the presence of subclinical atherosclerosis in different segments of the carotid artery. We recruited high-intensity athlete runners (n = 44) and controls (n = 51) to participate in the study. The carotid intima-media thickness (cIMT), interleukin 10 (IL-10), TNF-alpha, and the non-linear optical responses of LDL particle (Z-scan) were assessed. In athletes, the mean cIMT differed between genders, with higher values observed in female athletes compared to male athletes (P < 0.05). Higher mean values for cIMT were seen in the right carotid arteries of female athletes as compared to female controls (P < 0.05). Higher levels of TNF-alpha and IL-10 were found in athletes (P < 0.05). Yet, ΔΓpv (transmittance curve) of Z-scan in athletes was higher than in the non-athletes, indicating less oxidation in LDL particles of athletes (P < 0.05). There was an inverse association between the ΔΓpv and cIMT in the right internal carotid segments (ß = -0.163, P < 0.05) in all subjects, and between the VO2max and the mean cIMT (ß = -0.003, P < 0.05) in male subjects. The present study shows that the Z-scan technique enabled to detect less oxidative modifications in LDL particles from athletes. This effect was associated with cIMT in a gender-dependent mode.

Atletas , Artérias Carótidas/diagnóstico por imagem , Espessura Intima-Media Carotídea , Lipoproteínas LDL/metabolismo , Dinâmica não Linear , Fenômenos Ópticos , Adulto , Artérias Carótidas/patologia , Artérias Carótidas/fisiologia , Feminino , Humanos , Masculino , Oxirredução , Consumo de Oxigênio , Adulto Jovem
Am J Nephrol ; 43(3): 206-12, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27096580


BACKGROUND: This study aimed at evaluating the after effects of a single bout of aerobic exercise on muscle sympathetic nerve activity (MSNA), peripheral vascular resistance and blood pressure (BP) in stages 2-3 chronic kidney disease (CKD) patients. We hypothesized that CKD patients present a greater decline in these variables after the exercise than healthy individuals. METHODS: Nine patients with stages 2-3 CKD (50 ± 8 years) and 12 healthy volunteers (50 ± 5 years) underwent 2 sessions, conducted in a random order: exercise (45 min, cycle ergometer, 50% of peak oxygen uptake) and rest (seated, 45 min). Sixty minutes after either intervention, MSNA (by microneurography), BP (by oscillometry), and forearm vascular resistance (FVR) were measured. A 2-way analysis of variance with group (between) and session (within) as main factors was employed, accepting p < 0.05 as significant. RESULTS: Diastolic BP and MSNA were higher in the CKD than the control group in both sessions. Responses after exercise were similar in both groups. Systolic BP, diastolic BP, MSNA and FVR were significantly lower after the exercise than after the rest session in both the CKD and the control groups (162 ± 15 vs. 152 ± 23 and 155 ± 11 vs. 145 ± 16 mm Hg, 91 ± 11 vs. 85 ± 14 and 77 ± 5 vs. 71 ± 10 mm Hg, 38 ± 4 vs. 31 ± 4 and 34 ± 2 vs. 27 ± 4 burst/min, 59 ± 29 vs. 41 ± 29 and 45 ± 20 vs. 31 ± 8 U, respectively, all p < 0.05). CONCLUSION: These results showed that aerobic exercise may produce hemodynamic and neural responses that can be beneficial to these patients in spite of CKD.

Pressão Sanguínea , Exercício/fisiologia , Insuficiência Renal Crônica/fisiopatologia , Sistema Nervoso Simpático/fisiopatologia , Resistência Vascular/fisiologia , Adulto , Estudos de Casos e Controles , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
Br J Clin Pharmacol ; 70(5): 664-73, 2010 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-21039760


AIMS: This study was conducted to determine whether atenolol was able to decrease BP level and mitigate BP increase during dynamic resistance exercise performed at three different intensities in hypertensives. METHODS: Ten essential hypertensives (systolic/diastolic BP between 140/90 and 160/105mmHg) were blindly studied after 6 weeks of placebo and atenolol. In each phase, volunteers executed, in a random order, three protocols of knee-extension exercises to fatigue: (i) one set at 100% of 1RM; (ii) three sets at 80% of 1RM; and (iii) three sets at 40% of 1RM. Intra-arterial radial blood pressure was measured throughout the protocols. RESULTS: Atenolol decreased systolic BP maximum values achieved during the three exercise protocols (100% = 186 ± 4 vs. 215 ± 7, 80% = 224 ± 7 vs. 247 ± 9 and 40% = 223 ± 7 vs. 252 ± 16mmHg, P < 0.05). Atenolol also mitigated an increase in systolic BP in the first set of exercises (100% =+38 ± 5 vs.+54 ± 9; 80% =+68 ± 11 vs. +84 ± 13 and 40% =+69 ± 7 vs.+84 ± 14, mmHg, P < 0.05). Atenolol decreased diastolic BP values and mitigated its increase during exercise performed at 100% of 1RM (126 ± 6 vs. 145 ± 6 and +41 ± 6 vs.+52 ± 6, mmHg, P < 0.05), but not at the other exercise intensities. CONCLUSIONS: Atenolol was effective in both reducing systolic BP maximum values and mitigating BP increase during resistance exercise performed at different intensities in hypertensive subjects.

Anti-Hipertensivos/uso terapêutico , Atenolol/uso terapêutico , Pressão Sanguínea/efeitos dos fármacos , Exercício/fisiologia , Hipertensão/tratamento farmacológico , Adulto , Anti-Hipertensivos/farmacologia , Atenolol/farmacologia , Pressão Sanguínea/fisiologia , Feminino , Humanos , Hipertensão/fisiopatologia , Masculino , Pessoa de Meia-Idade , Treinamento de Resistência/métodos