Low-Load x High-Load Resistance Exercise: Greater Cell Swelling After a Training Session.

Cell swelling caused by resistance training is proposed to provide an anabolic stimulus for muscle growth and it is believed that these effects are heightened with the use of low loads. The purpose of this study was to compare the acute effects of two volume-equated resistance training (RT) protocols, low-load (LL) versus high-load (HL), on elbow flexor muscles thickness, arm circumference, and blood lactate concentration in well-trained individuals. Eight resistance-trained males performed the following two RT protocols involving unilateral elbow flexion of the dominant arm: i) LL, four sets with 50% 1 repetition-maximum [1 RM] and ii) HL, ten sets with 85% 1 RM until failure, and equated volume. Pre- and post-session measurements included muscle thickness of the elbow flexors (biceps brachii and brachialis), upper arm circumference, and blood lactate concentration. Significant pre- to post-session increases were found in both protocols for muscle thickness (F (1, 28) = 11.74, p = 0.0019), and blood lactate (F (1, 28) = 35.55, p < 0.0001); no statistically significant differences were observed between conditions, however, the magnitude of increases favored LL. Significant between-condition differences favoring LL were observed for total repetitions (p = 0.007), time under tension (p = 0.007), and training density (p = 0.007). These results suggest that LL training promotes superior post-session increases in muscle thickness, indicating that RT protocols with longer times under tension and densities are beneficial when the goal is to promote acute cell swelling.

Backseat Inclination Affects the Myoelectric Activation During the Inclined Leg Press Exercise in Recreationally Trained Men.

ABSTRACT: Marchetti, PH, Gomes, WA, Da Silva, JJ, Magalhaes, RA, Teixeira, LFM, and Whiting, WC. Backseat inclination affects the myoelectric activation during the inclined leg press exercise in recreationally trained men. J Strength Cond Res 37(10): e541-e545, 2023-Changes in the angle between the seat and backrest during the inclined leg press (ILP) exercise may influence myoelectric activity. The purpose of this study was to evaluate the myoelectric activity between 2 different angles between the seat and backrest (90° and 125°) during the ILP exercise in recreationally trained men. Fifteen young, resistance-trained men (age: 26.8 ± 5.3 years, height: 173.8 ± 6.6 cm, total body mass: 81.6 ± 7.6 kg) performed 1 set of 10 repetitions at 70% of their body mass during the ILP exercise using 2 different angles between the seat and backrest (ILP90° and ILP125°). Surface electromyography (peak RMS 90 and iEMG) was used to measure the myoelectric activity of the vastus lateralis (VL), biceps femoris (BF), and gluteus maximus (GM). A paired t test was used to measure differences in knee and hip joint displacement, peak RMS 90 , and iEMG between ILP90 and ILP125. The hip angle presented a greater displacement during the ILP125 when compared with ILP90 ( p < 0.001), considering a similar knee joint displacement. For the VL, there was observed greater myoelectric activation (peak RMS 90 and iEMG) during ILP125 when compared with ILP90 ( p < 0.05). For the BF, there was observed greater myoelectric activation (peak RMS 90 and iEMG) during ILP90 when compared with ILP125 ( p < 0.05). However, GM did not present differences between ILP90 and ILP125. In conclusion, the angle between the seat and backrest (ILP90 or ILP125) altered the myoelectric activation of the VL and BF with no difference for the GM.

Hypopressive exercise in normotensive young women: A case series.

Hypopressive exercise (HE) has been contraindicated for people with cardiovascular disease because it involves isometric postures performed with low-pulmonary volume breath-holds, which are thought to increase blood pressure. The objective of this study was to analyze the hemodynamic responses to HE performed in the seated posture on systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP) and heart rate (HR) in normotensive females. Ten women (age = 31.2 ± 6.3 years) with previous experience in HE participated. Three sets of eight breathing cycles of HE breathing were completed. The HE breathing protocol consisted of three complete breathing cycles of controlled latero-costal inhalations and slow deep exhalations followed by a breath-hold and rib-cage expansion after every third exhalation. Measurements of SBP, DBP, MAP and HR were assessed at baseline, at the end of each set and at the end of minute 5, 10, 15 and 20 during the recovery period. The measurement of hemodynamic variables used a digital photoplethysmography device. Significant differences for SBP (baseline compared to SET2, p = 0.0182) and MAP (baseline compared to SET1, p = 0.0433; and SET2, p = 0.0072) were found. No significant differences were found in the recovery periods compared with baseline. Medium effect size for HR during REC5 (ES = 0.50) and REC10 (ES = 0.56) was observed. These findings indicate that HE in the seated posture performed by normotensive females leads to significant increases in SBP and MAP with no significant increase of HR and no hypotensive effect during recovery period. Our preliminary results should be supported by future randomized controlled trials.

Does the Timing of Measurement Alter Session-RPE in Boxers?

The purpose of this study was to compare the influence of measuring the overall session rating of perceived exertion (session-RPE) at 10 vs. 30 minutes following exercise. Eight boxers completed three different standardized training sessions of different intensities (easy, moderate and hard) in a matchedpairs, randomized research design. Exercise intensity was assessed during each bout by measuring heart rate, blood lactate concentration and session-RPE. To assess the effect of measurement timing on session-RPE, RPE data were collected either 10 or 30 minutes post-exercise. There was no significant effect of measurement time on session-RPE values following easy (10 minutes: session-RPE = 1.3 ± 1.0 Arbitrary Unit (AU), %Heart Rate Reserve (HRR) = 49.5 ± 11.1, and ∆Blood lactate = -2.3 ± 16.3%; 30 minutes: session-RPE = 1.7 ± 1.0 AU, %HRR = 51.3 ± 10.8, and ∆Blood lactate = 0.7 ± 25.2%), moderate (10 minutes: session-RPE = 2.7 ± 1.6 AU, %HRR = 67.2 ± 10.8, and ∆Blood lactate = 2.2 ± 19%; 30 minutes: session-RPE = 2.5 ± 0.9 AU, %HRR = 67.2 ± 5.9, and ∆Blood lactate = 24.5 ± 17.1%) and hard (10 minutes: session-RPE = 5.7 ± 1.0 AU, %HRR = 88.1 ± 6.3, and ∆Blood lactate = 146.3 ± 87.9%; 30 minutes: session-RPE = 5.8 ± 1.9 AU, %HRR> = 83.3 ± 8.0, and ∆Blood lactate = 91.6 ± 39%) sessions. In conclusion, our findings suggest that session-RPE can be used in boxing training routines across a range of intensities and accurate measurements can be determined as early as 10 minutes after exercise. Key PointsIt is difficult to quantify and monitoring the external training load in martial arts (e.g. Aikido, Kung Fu, Judo) and physical combat sports (e.g. Boxing, Muay Thai), session RPE method appears to be a reliable method to quantifying training load in those sports.For many athletes it is impractical to wait 30 minutes after training session to provide a session-RPE. The present findings show that collecting ses-sion-RPE measures at 10 min following exercise ses-sions of various intensities (i.e. easy, moderate, and hard) provide similar values as if taken 30 min fol-lowing the session.Our data have significant practical benefit and fur-ther support the practical usefulness of session-RPE for measuring internal training load in sport.

Exercícios de força e parâmetros imunológicos_contagem leucocitária, inflamação e regeneração / Strength exercise and immunological parameters_ leukocytes counting, inflammation and regeneration

Recentemente, a prescrição de exercícios aeróbios, bem como sua associação com os de força, têm sido recomendados pelas principais agências normativas de saúde. Sessões agudas ou treinamento crônico promovem respostas no sistema imunológico, podendo acarretar desistência, não continuidade ou queda no desempenho nos programas de exercícios, pela aumentada susceptibilidade às infecções oportunistas, principalmente infecções do trato respiratório superior (ITRS). Assim, o objetivo do estudo foi investigar as modulações decorrentes dos exercícios de força quanto à contagem leucocitária, dano, inflamação, regeneração muscular e susceptibilidade às ITRS. Foi realizada uma revisão de periódicos nacionais e internacionais nos portais científicos da Capes, Scielo, Science Direct e Highwire. Sugere-se que a leucocitose pode ter como função, preparar o organismo para uma possível demanda celular nos músculos, constituindo-se em uma forma do sistema imunológico se antecipar às necessidades de remodelagem tecidual. A infiltração leucocitária nos tecidos danificados apresenta forte relação na ativação das células satélites e queda na força, demonstrando um padrão bi-modal de recuperação. As pequenas flutuações na contagem leucocitária, especificamente nos linfócitos, após os exercícios de força, quando comparadas aos aeróbios, parecem ser respostas agudas com pouco significado clínico, sem relação com aumento nas ITRS.

Recently, endurance exercises prescription as well as its association with strength exercises, has been recommended by main normative health societies. Acute bouts or chronic training, promote responses in immune system, possibly leading to burn out, none continuity or performance decrease in exercise programs, caused by the increased susceptibility of opportunist infections, mainly upper respiratory tract infections (URTI). Thus, the objective of this study was to investigate the modulations originated from strength exercises as leucocyte counting, damage, inflammation, muscular regeneration and susceptibility to URTI. A revision of national and international periodics was carried through scientific halls such as Capes, Scielo, Science Direct and Highwire. It is suggested that leukocytosis may exert a function of preparing the organism for possible cellular demand in muscle, so that it can be a manner by witch immunological system anticipates to tissue remodeling necessities. Leucocyte infiltration in damaged tissues presents a strong bound in satellites cells activation and strength decrease, showing a bi-modal pattern of recovery. The small fluctuations in the leucocytes counting, specifically in the lymphocytes, after strength exercises, when compared with aerobic exercises, seems to be acute responses with little clinical relevance, without relation to the increase in the URTI.