Interset Stretching vs. Traditional Strength Training: Effects on Muscle Strength and Size in Untrained Individuals.

Evangelista, AL, De Souza, EO, Moreira, DCB, Alonso, AC, Teixeira, CVLS, Wadhi, T, Rauch, J, Bocalini, DS, Pereira, PEDA, and Greve, JMDA. Interset stretching vs. traditional strength training: effects on muscle strength and size in untrained individuals. J Strength Cond Res 33(7S): S159-S166, 2019-This study compared the effects of 8 weeks of traditional strength training (TST) and interset stretching (ISS) combined with TST on muscular adaptations. Twenty-nine sedentary, healthy adults were randomly assigned to either the TST (n = 17; 28.0 ± 6.4 years) or ISS (n = 12; 26.8 ± 6.1 years) group. Both groups performed 6 strength exercises encompassing the whole body (bench press, elbow extension, seated rows, biceps curl, knee extension, and knee flexion) performing 4 sets of 8-12 repetition maximum (RM) with a 90-second rest between sets. However, the ISS group performed static passive stretching, at maximum amplitude, for 30 seconds between sets. Both groups performed training sessions twice a week on nonconsecutive days. Muscle strength (i.e., 1RM) and hypertrophy (i.e., muscle thickness [MT] by ultrasonography) were measured at pre-test and after 8 weeks of training. Both groups increased 1RM bench press (p ≤ 0.0001): ISS (23.4%, CIdiff: 4.3 kg-11.1 kg) and TST (22.2%, CIdiff: 5.2 kg-10.9 kg) and 1RM knee extension (p ≤ 0.0001): ISS (25.5%, CIdiff: 5.6 kg-15.0 kg) and TST (20.6%, CIdiff: 4.4 kg-12.3 kg). Both groups increased MT of biceps brachii (BIMT), triceps brachii (TRMT), and rectus femoris (RFMT) (p ≤ 0.0001). BIMT: ISS (7.2%, CIdiff: 1.14-3.5 mm) and TST (4.7%, CIdiff: 0.5-2.5 mm), TRMT: ISS (12.3%, CIdiff: 1.1-4.4 mm) and TST (7.1%, CIdiff: 0.3-3.1 mm), and RFMT: ISS (12.4%, CIdiff: 1.1-2.9 mm) and TST (9.1%, CIdiff: 0.7-2.2 mm). For vastus lateralis muscle thickness (VLMT) and sum of the 4 muscle thickness sites (ΣMT), there was a significant group by time interaction (p ≤ 0.02) in which ISS increased VLMT and ΣMT to a greater extent than TST. Vastus lateralis muscle thickness: ISS (17.0%, CIdiff: 1.5-3.1 mm) and TST (7.3%, CIdiff: 0.7-2.1 mm), and ΣMT: ISS (10.5%, CIdiff: 6.5-9.0 mm) and TST (6.7%, CIdiff: 3.9-8.3 mm). Although our findings might suggest a benefit of adding ISS into TST for optimizing muscle hypertrophy, our data are not sufficient enough to conclude that ISS is superior to TST for inducing muscle hypertrophic adaptations. More studies are warranted to elucidate the effects of ISS compared with TST protocols on skeletal muscle. However, our findings support that adding ISS to regular TST regimens does not compromise muscular adaptations during the early phase of training (<8 weeks) in untrained individuals.

Alternative methods for estimating maximum lactate steady state velocity in physically active young adults / Métodos alternativos para estimar a velocidade da máxima fase estável de lactato em adultos jovens fisicamente ativos

The aim of this study was to compare the velocities found in the protocols used to measure the indirect individual anaerobic threshold (IATind), glucose threshold (GT) and critical velocity (CV) with the gold standard, the maximum lactate steady state (MLSS) protocol. Fourteen physically active young adults (23±3.1 years; 72±10.97 kg; 176±7 cm; 21±5.36% body fat) performed a 3000-m track running test to determine IATind using the prediction equation and an incremental test on a treadmill to determine GT. The CV was identified by linear regression of the distance-time relationship based on 3000-m and 500-m running performance. The MLSS was identified using two to five tests on different days to identify the intensity at which there was no increase in blood lactate concentration greater than 1 mmol/L between the 10th and 30th minute. A significant difference was observed between mean CV and MLSS (P≤0.05) and there was a high correlation between MLSS and IATind (R2=0.82; P≤0.01) and between MLSS and GT (R2=0.72; P≤0.01). The Bland-Altman method showed agreement between MLSS and IATind [mean difference -0.24 (confidence interval -1.72 to 1.24) km/h] and between MLSS and GT [0.21 (-1.26 to 1.29) km/h]. We conclude that the IATind and GT can predict MLSS velocity with good accuracy, thus making the identification of MLSS practical and efficient to prescribe adequate intensities of aerobic exercise.

O objetivo do presente estudo foi comparar as velocidades encontradas nos protocolos de Limiar Anaeróbio Individual Indireto (LAIind), Limiar Glicêmico (LG) e Velocidade Crítica (VC) com o padrão ouro, o protocolo de identificação da máxima fase estável do lactato (MFEL). Participaram 14 adultos jovens fisicamente ativos (23±3,1 anos; 72±10,97 kg; 1,76±0,07 m; 21±5,36 % gordura corporal) que realizaram um teste de 3000m em pista para determinar o LAIind através de equação de predição; teste incremental em esteira ergométrica para determinação do LG; a VC foi identificada por regressão linear através da relação distância-tempo com base no desempenho em corridas nas distâncias de 3.000m e 500m; a MFEL foi identificada utilizando de dois a cinco testes em dias distintos até encontrar a intensidade onde não houve aumento da concentração de lactato sanguíneo maior que 1 mmol.L-1 entre os minutos 10 e 30. Houve diferença estatística entre os valores médios da VC e a MFEL (P≤0,05), elevada correlação entre MFEL e LAIind (R2=0,82; P≤0.01) e MFEL e LG (R2=0,72; P≤0.01). Através do método Bland-Altman foram encontradas as concordâncias entre MFEL e LAIind [diferença média -0,24 (intervalo de confiança -1,72 a 1,24) km/h] e MFEL e LG [0,21 (-1,26 a 1,29) km/h]. Concluímos que o LAIind e o LG são testes que podem predizer com boa precisão a velocidade da MFEL, tornando sua identificação prática e eficiente para prescrição de intensidades adequadas para o treinamento aeróbio.

Efeito agudo da suplementação de cafeína sobre o desempenho físico durante teste incremental de esforço / Acute effect of caffeine suplementation on physical performance during an incremental effort test

O presente estudo teve como objetivo investigar os efeitos da ingestão de cafeína (CAF) sobre a velocidade de corrida (VC) referente à intensidade do primeiro limiar ventilatório (LV1) e velocidade máxima de corrida (Vmáx). Para tanto, oito mulheres saudáveis, ativas fisicamente, realizaram dois testes incrementais máximos (TImáx) em esteira ergométrica em duas condições diferentes, sob ingestão de CAF e placebo (PLA). Para contrastar os dados, utilizou-se o teste t de Student pareado. Houve diferença significativa (P ≤0,05) na VC (PLA 7,87 ± 1,72 km/h, CAF 8,50 ± 1,69 km/h), na frequência cardíaca (PLA 152,37 ± 21,41 bpm, CAF 167,00 ± 14,71 bpm) e na VE (PLA 31,40 ± 8,53 L/min, CAF 34,46 ± 9,52 L/min), na intensidade referente ao LV1. Diferentemente, na Vmáx não foram observadas diferenças significativas na VC, FC e vetilação (VE) em ambas as condições. É possível concluir que a VC, FC e VE foram modificadas com a suplementação de CAF na intensidade do LV1, mas não na Vmáx.

The present study aimed to investigate the effects of caffeine (CAF) ingestion on running speed (RS) on the intensity of the first ventilatory threshold (VT1) and maximum running speed (Vmax). Therefore, eight healthy women, physically active performed two maximal incremental tests (TImax) on the treadmill at two different conditions under CAF intake and placebo (PLA). To contrast the data, we used the paired Student t test. There were statistically significant differences (P ≤ 0.05) in RS (PLA 7.87 ± 1.72 km / h, 8.50 ± 1.69 CAF km / h), heart rate (PLA 152.37 ± 21.41 bpm, CAF 167.00 ± 14.71 bpm) and LV (PLA 31.40 ± 8.53 L / min, CAF 34.46 ± 9.52 L / min), the intensity for the VT1. In contrast, the Vmax were not significant differences in VC, HR and ventilation (VE) in both conditions. It is possible to conclude that the VC, VE and HR were modified with the supplementation of CAF in the intensity of VT1, but not in the Vmax.