This study compared acute responses of systolic and diastolic blood pressure (SBP/DBP), cardiac output (Q), heart rate (HR), stroke volume (SV), total peripheral resistance (TPR) and rate of perceived exertion (RPE) during resistance exercise performed continuously and discontinuously. Hemodynamic responses and RPE were assessed in the last of 4 sets of 12 repetitions of the knee extension with load corresponding to 70% of 12 repetition maximum, performed continuously (C) or discontinuously, with pauses of 5 s (D5) or 10 s (D10) interspersed in the middle of sets. The increase in SBP was higher for D10 (34.0±8.4%) and D5 (34.1±13.2%) vs. C (19.8±10.3%; P<0.001), while no difference was detected for DBP. Q (P=0.03) and SV (P=0.02) were higher, but HR was lower (P=0.04) in discontinuous vs. continuous. TPR remained stable during continuous, but significant decreases occurred during the pauses in the discontinuous protocols (P<0.001). The BP was higher in discontinuous than in continuous protocols, but the RPE was attenuated in discontinuous compared to continuous exercise. In conclusion, hemodynamic responses were exacerbated during resistance exercise performed discontinuously, but the perceived exertion was lowered.

Prior research about the effects of the amount of exercised muscle mass upon cardiovascular responses (CVR) has neglected a potential bias related to total exercise and concentric/eccentric duration. Autonomic responses and perceived exertion (RPE) were compared in resistance exercises performed with larger and smaller muscle mass and matched for total exercise and concentric/eccentric duration. Twelve men performed 4 sets of 12 repetitions of unilateral (UNI) and bilateral (BIL) knee extensions at 70% of 12RM. Increases in CVR were always greater at the last set of BIL over UNI, as were SBP (35% vs. 23%), DBP (36% vs. 23%), HR (40% vs. 26%), RRP (90% vs 53%) and CO (55% vs 39%). No difference between protocols was found for autonomic modulation before and after exercise, but BIL induced significantly greater changes than UNI from baseline for R-R intervals (-13% vs. -7%), SDNN (-38% vs. -17%) and rMSSD (-41% vs. -21%). The rate of perceived exertion in the last set was higher in BIL than UNI (7.6±0.5 vs. 6.6±1.4 OMNI-RES; P<0.05) and did not correlate with any CVR. Thus, CVR were greater in resistance exercise performed with larger than smaller muscle mass. This information is relevant for patients with high cardiovascular risk.

Volume 12, número 4, outubro-dezembro/2013 99 ResumoEvidências indicam que reduções crônicas na pressão arterial (PA) provocadas por exercício físico dependem, em grande medida, da capacidade de se induzir após cada sessão de treinamento o fenômeno da hipotensão pós-exercício (HPE). A presente revisão descreve artigos sobre contribuição do exercício aeróbio, de força e concorrente para a HPE, bem como apresenta possíveis mecanismos fisiológicos envolvidos. A ocorrência de HPE após diferentes tipos de exercício parece ser bem-aceita, tanto em indivíduos normotensos, quanto hipertensos. Contudo, a dose ótima de exercício aeróbio (ex.: relação entre intensidade, duração, modo de exercício e forma de execução) e de força (ex.: relação entre intensidade, volume e massa muscular envolvida) para maximizá-la permanece incerta. Dúvidas também persistem em relação aos diversos mecanismos fisiológicos envolvidos na HPE, que parecem ser diferentes no exercício aeróbio e de força. Destacam-se os mecanismos centrais e locais associados, respectivamente, à diminuição do débito cardíaco (DC) e resistência vascular periférica (RVP). Nesse sentido, os mecanismos envolvidos na HPE após o exercício aeróbio associar-se-iam tanto a fatores centrais (ex.: diminuição da atividade nervosa simpática), quanto a fatores periféricos (ex.: vasodilatação sustentada pela liberação de óxido nítrico, prostaglandinas e receptores da histamina). Na força, a HPE parece relacionarse, principalmente, com a diminuição do DC e a queda do volume sistólico, em resposta à menor perfusão miocárdica ocasionada pela maior compressão sequencial dos vasos. Descritores: Pressão arterial; Fisiologia cardiovascular; Exercício; Promoção da saúde. AbstractEvidence indicates that chronic reduction in blood pressure (BP) due to physical exercise depends on the acute decrease in BP after a training bout, phenomenon referred as post-

It has been proposed that fatigue during strength exercise is negatively influenced by prior proprioceptive neuromuscular facilitation (PNF) stretching. However, it is possible that the effects of PNF on muscle endurance are affected by stretching duration. This study investigated the influence of PNF on the number of repetitions of the leg curl exercise performed with multiple sets and submaximal load. Nineteen men (age 25 ± 1 years, weight 75.8 ± 4.2 kg, height 178.1 ± 3.8 cm, 10-repetition maximum [RM] 78.3 ± 6.9 kg) performed 4 sets of leg curl with 10RM load with and without previous PNF (3 sets of hip flexion either with knees extended or flexed, duration ~2.5 minutes). The total number of repetitions decreased along sets in both situations (38.6% in control and 41.0% in PNF sessions, p < 0.001). However, no difference between control and PNF was detected for the number of repetitions in each set (first set, p = 0.330; second set, p = 0.072; third set, p = 0.061; fourth set, p = 0.150). In conclusion, the number of repetitions performed in multiple sets of the leg curl was not decreased by prior PNF stretching. Therefore, it appears that a moderate level of PNF could be used before resistance exercise with a minimal negative effect.

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