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1.
Exp Physiol ; 104(12): 1858-1867, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31613029

RESUMO

NEW FINDINGS: What is the central question of this study? Can interval blood-flow-restricted (BFR) cycling training, undertaken at a low intensity, promote a similar adaptation to oxygen uptake ( V̇O2 ) kinetics to high-intensity interval training? What is the main finding and its importance? Speeding of pulmonary V̇O2 on-kinetics in healthy young subjects was not different between low-intensity interval BFR training and traditional high-intensity interval training. Given that very low workloads are well tolerated during BFR cycle training and speed V̇O2 on-kinetics, this training method could be used when high mechanical loads are contraindicated. ABSTRACT: Low-intensity blood-flow-restricted (BFR) endurance training is effective to increase aerobic capacity. Whether it speeds pulmonary oxygen uptake ( V̇O2p ), CO2 output ( V̇CO2p ) and ventilatory ( V̇Ep ) kinetics has not been examined. We hypothesized that low-intensity BFR training would reduce the phase 2 time constant (τp ) of V̇O2p , V̇CO2p and V̇Ep by a similar magnitude to traditional high-intensity interval training (HIT). Low-intensity interval training with BFR served as a control. Twenty-four participants (25 ± 6 years old; maximal V̇O2 46 ± 6 ml kg-1  min-1 ) were assigned to one of the following: low-intensity BFR interval training (BFR; n = 8); low-intensity interval training without BFR (LOW; n = 7); or high-intensity interval training without BFR (HIT; n = 9). Training was 12 sessions of two sets of five to eight × 2 min cycling and 1 min resting intervals. LOW and BFR were conducted at 30% of peak incremental power (Ppeak ), and HIT was at ∼103% Ppeak . For BFR, cuffs were inflated on both thighs (140-200 mmHg) during exercise and deflated during rest intervals. Six moderate-intensity step transitions (30% Ppeak ) were averaged for analysis of pulmonary on-kinetics. Both BFR (pre- versus post-training τp  = 18.3 ± 3.2 versus 14.5 ± 3.4 s; effect size = 1.14) and HIT (τp  = 20.3 ± 4.0 versus 13.1 ± 2.9 s; effect size = 1.75) reduced the V̇O2p τp (P < 0.05). As expected, there was no change in LOW ( V̇O2p τp  = 17.9 ± 6.2 versus 17.7 ± 4.3 s; P = 0.9). The kinetics of V̇CO2p and V̇Ep were speeded only after HIT (38.5 ± 10.6%, P < 0.001 and 31.2 ± 24.7%, P = 0.004, respectively). Both HIT and low-intensity BFR training were effective in speeding moderate-intensity V̇O2p kinetics. These data support the findings of others that low-intensity cycling training with BFR increases muscle oxidative capacity.


Assuntos
Exercício Físico/fisiologia , Treinamento Intervalado de Alta Intensidade/métodos , Músculo Esquelético/irrigação sanguínea , Músculo Esquelético/fisiologia , Consumo de Oxigênio/fisiologia , Fluxo Sanguíneo Regional/fisiologia , Adulto , Treino Aeróbico/métodos , Feminino , Humanos , Masculino , Distribuição Aleatória , Adulto Jovem
2.
J Strength Cond Res ; 33(2): 408-416, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-28704307

RESUMO

Lisbôa, FD, Raimundo, JAG, Salvador, AF, Pereira, KL, Turnes, T, Diefenthaeler, F, Oliveira, MFMd, and Caputo, F. Acute cardiopulmonary, metabolic, and neuromuscular responses to severe-intensity intermittent exercises. J Strength Cond Res 33(2): 408-416, 2019-The purpose of this study was to compare cardiopulmonary, neuromuscular, and metabolic responses to severe-intensity intermittent exercises with variable or constant work rate (CWR). Eleven cyclists (28 ± 5 years; 74 ± 7 kg; 175 ± 5 cm; 63 ± 4 ml·kg·min) performed the following tests until exhaustion on separate days: (a) an incremental test; (b) in random order, 2 CWR tests at 95 and 110% of the peak power for the determination of critical power (CP); (c) 2-4 tests for the determination of the highest power that still permits the achievement of maximal oxygen uptake (PHIGH); and (d) 2 random severe-intensity intermittent exercises. The last 2 sessions consisted of a CWR exercise performed at PHIGH or a decreasing work rate (DWR) exercise from PHIGH until 105% of CP. Compared with CWR, DWR presented higher time to exhaustion (635 ± 223 vs. 274 ± 65 seconds), time spent above 95% of V[Combining Dot Above]O2max (t95% V[Combining Dot Above]O2max) (323 ± 227 vs. 98 ± 65 seconds), and O2 consumed (0.97 ± 0.41 vs. 0.41 ± 0.11 L). Electromyography amplitude (root mean square [RMS]) decreased for DWR but increased for CWR during each repetition. However, RMS and V[Combining Dot Above]O2 divided by power output (RMS/PO and V[Combining Dot Above]O2/PO ratio) increased in every repetition for both protocols, but to a higher extent and slope for DWR. These findings suggest that the higher RMS/PO and V[Combining Dot Above]O2/PO ratio in association with the longer exercise duration seemed to have been responsible for the higher t95% V[Combining Dot Above]O2max observed during severe DWR exercise.


Assuntos
Ciclismo/fisiologia , Fadiga/fisiopatologia , Treinamento Intervalado de Alta Intensidade/métodos , Consumo de Oxigênio/fisiologia , Adulto , Eletromiografia , Feminino , Frequência Cardíaca/fisiologia , Humanos , Ácido Láctico/sangue , Masculino , Taxa Respiratória/fisiologia , Fatores de Tempo , Adulto Jovem
3.
J Strength Cond Res ; 27(5): 1450-4, 2013 May.
Artigo em Inglês | MEDLINE | ID: mdl-22744415

RESUMO

The purpose of this study was to identify the boundary of submaximal speed zones (i.e., exercise intensity domains) between maximal aerobic speed (S-400) and lactate threshold (LT) in swimming. A 400-m all-out test, a 7 × 200 m incremental step test, and two to four 30-minute submaximal tests were performed by 12 male endurance swimmers (age = 24.5 ± 9.6 years; body mass = 71.3 ± 9.8 kg) to determine S-400, speed corresponding to LT, and maximal lactate steady state (MLSS). S-400 was 1.30 ± 0.09 m·s (400 m-5:08 minutes:seconds). The speed at LT (1.08 ± 0.02 m·s; 83.1 ± 2.2 %S-400) was lower than the speed at MLSS (1.14 ± 0.02 m·s; 87.5 ± 1.9 %S-400). Maximal lactate steady state occurred at 26 ± 10% of the difference between the speed at LT and S-400. Mean blood lactate values at the speeds corresponding to LT and MLSS were 2.45 ± 1.13 mmol·L and 4.30 ± 1.32 mmol·L, respectively. The present findings demonstrate that the range of intensity zones between LT and MLSS (i.e., heavy domain) and between MLSS and S-400 (i.e., severe domain) are very narrow in swimming with LT occurring at 83% S-400 in trained swimmers. Precision and sensitivity of the measurement of aerobic indexes (i.e., LT and MLSS) should be considered when conducting exercise training and testing in swimming.


Assuntos
Desempenho Atlético/fisiologia , Educação Física e Treinamento/métodos , Resistência Física , Natação/fisiologia , Limiar Anaeróbio , Teste de Esforço , Humanos , Masculino , Adulto Jovem
4.
Int J Sports Physiol Perform ; 7(3): 218-23, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22172986

RESUMO

PURPOSE: To identify the speed corresponding to anaerobic threshold using the D-max method for both blood lactate and biomechanical stroke parameters determined in an incremental swimming test and to compare this information with the speed corresponding to the maximal lactate steady state (SMLSS). METHODS: Five male long-distance swimmers and 8 triathletes (N=13; age 23.8±9.5 y, height 1.76±0.1 m, weight 71.3±9.8 kg) performed the following protocols: maximal 400-m test to determine maximal aerobic speed (S400); 7×200-m incremental test to determine the speed corresponding to the D-max point on the blood lactate (SLa), stroke-rate (SSR), stroke-length (SSL), and stroke-index (SSI) responses; and two to four 30-min submaximal tests to determine the SMLSS. RESULTS: SLA (1.18±0.08 m/s), SSI (1.18±0.08 m/s), SSR (1.17±0.1 m/s), and SSL (1.16±0.09 m/s) were not significantly different from each other or from SMLSS (1.13±0.08 m/s). There were high correlations between SLA, SSI, SSR, SSL, and SMLSS (r=.91, .89, .85, and .80, respectively). The typical errors of estimate for SLA (3.2%), SSI (3.7%), SSR (4.1%), and SSL (4.7%) suggest good validity of these variables to predict SMLSS. Furthermore, all physiological and biomechanical variables were moderately to highly correlated with S400 (r=.73-.95). CONCLUSIONS: It is possible to obtain a physiological index of aerobic capacity and performance using simple biomechanical measurements during an incremental test without performing blood lactate analyses.


Assuntos
Desempenho Atlético , Contração Muscular , Músculo Esquelético/fisiologia , Natação , Adolescente , Adulto , Limiar Anaeróbio , Biomarcadores/sangue , Fenômenos Biomecânicos , Humanos , Ácido Láctico/sangue , Masculino , Reprodutibilidade dos Testes , Análise e Desempenho de Tarefas , Adulto Jovem
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