Flow-Mediated Dilation in Healthy Young Individuals Is Impaired after a Single Resistance Exercise Session

The current pool of data investigating the effects of a single resistance exercise session on endothelial function is divergent and inconclusive. Therefore, the purpose of the present study was to evaluate the effect of a single resistance exercise session on flow-mediated dilation (FMD) in trained individuals. Eleven healthy, young, recreationally resistance-trained individuals participated in the study. After determining the resistance exercise workload, the participants performed three sets of 10–12 repetition of leg press and leg extension exercises. By using ultrasound equipment, brachial artery FMD was assessed before (PRE) and 30 min after (POST) the resistance exercise protocol or resting (control) to evaluate endothelial function. A significant reduction in FMD response (PRE: 5.73% ± 1.21% vs. POST: 4.03% ± 1.94%, p < 0.01) after resistance exercise was observed, accompanied by a large effect size (d = 1.05). No significant difference was observed in FMD in the control condition (PRE: 5.82% ± 1.19% vs. POST: 5.66% ± 1.24%, p = 0.704). Additionally, no significant difference in baseline brachial artery diameter between resistance exercise (PRE: 3.30 ± 0.32 vs. POST: 3.40 ± 0.34 mm, p = 0.494) and resting (PRE: 3.64 ± 0.41 vs. POST: 3.67 ± 0.62 mm, p = 0.825) was observed. Our findings showed that a single resistance exercise session induced a reduction in FMD in resistance-trained individuals.

Test-Retest Reliability of the One-Repetition Maximum (1RM) Strength Assessment: a Systematic Review

Background

The test–retest reliability of the one-repetition maximum (1RM) test varies across different studies. Given the inconsistent findings, it is unclear what the true reliability of the 1RM test is, and to what extent it is affected by measurement-related factors, such as exercise selection for the test, the number of familiarization trials and resistance training experience.

Objectives

The aim of this paper was to review studies that investigated the reliability of the 1RM test of muscular strength and summarize their findings.

Methods

The PRISMA guidelines were followed for this systematic review. Searches for studies were conducted through eight databases. Studies that investigated test–retest reliability of the 1RM test and presented intra-class correlation coefficient (ICC) and/or coefficient of variation (CV) were included. The COSMIN checklist was used for the assessment of the methodological quality of the included studies.

Results

After reviewing 1024 search records, 32 studies (pooled n = 1595) on test–retest reliability of 1RM assessment were found. All the studies were of moderate or excellent methodological quality. Test–retest ICCs ranged from 0.64 to 0.99 (median ICC = 0.97), where 92% of ICCs were ≥ 0.90, and 97% of ICCs were ≥ 0.80. The CVs ranged from 0.5 to 12.1% (median CV = 4.2%). ICCs were generally high (≥ 0.90), and most CVs were low (< 10%) for 1RM tests: (1) among those without and for those with some resistance training experience, (2) conducted with or without familiarization sessions, (3) with single-joint or multi-joint exercises, (4) for upper- and lower-body strength assessment, (5) among females and males, and (6) among young to middle-aged adults and among older adults. Most studies did not find systematic changes in test results between the trials.

Conclusions

Based on the results of this review, it can be concluded that the 1RM test generally has good to excellent test–retest reliability, regardless of resistance training experience, number of familiarization sessions, exercise selection, part of the body assessed (upper vs. lower body), and sex or age of participants. Researchers and practitioners, therefore, can use the 1RM test as a reliable test of muscular strength.

Effects of fish protein hydrolysate ingestion on postexercise aminoacidemia compared with whey protein hydrolysate in young individuals

The aminoacidemia resulting from food protein digestion in response to exercise plays an underlying role in the rate of muscle protein synthesis. Whey protein hydrolysate (WPH) has been demonstrated to cause more pronounced postexercise aminoacidemia compared with casein and soy. Although fish protein has been demonstrated to be a great source of amino acids, there is no data available providing information about the postexercise aminoacidemia after fish protein hydrolysate (FPH) intake. The present study investigated the characteristic patterns of postexercise aminoacidemia after WPH and FPH intake in nine physically active subjects (six males and three females). In a crossover, double-blind, and randomized design, all participants received oral doses of either 0.25 g/kg of FPH or WPH or placebo (PLA) immediately after a resistance exercise bout. Blood samples were taken before and at 30, 60, 90, 120 and 180 min after supplementation. There was a significant increase in plasma total amino acids (TAA), essential amino acids (EAA), branched-chain amino acids (BCAA), and leucine concentrations at 30 and 60 min after FPH supplementation, and at 30, 60, 90, and 120 min after WPH as compared to PLA. No significant differences were observed in plasma TAA, EAA, BCAA, and leucine concentrations between FPH and WPH at any time point, and there were no significant difference observed in the area under the curve for TAA, EAA, BCAA, and leucine between FPH and WPH. In conclusion, both FPH and WPH showed a rapid and pronounced postexercise aminoacidemia. FPH presented itself to be an alternative food source of rapidly digested proteins to be used after resistance exercise. PRACTICAL APPLICATION: Fish protein hydrolysate (FPH) demonstrated a rapid and pronounced postexercise aminoacidemia. Whey protein hydrolysate showed similar effects. FPH is presented as an alternative food source of rapidly digested proteins to be consumed by the population, especially physically active individuals.

The impact of test loads on the accuracy of 1RM prediction using the load-velocity relationship

BACKGROUND

Numerous methods have been proposed that use submaximal loads to predict one repetition maximum (1RM). One common method applies standard linear regression equations to load and average vertical lifting velocity (Vmean) data developed during squat jumps or three bench press throw (BP-T). The main aim of this project was to determine which combination of three submaximal loads during BP-T result in the most accurate prediction of 1RM Smith Machine bench press strength in healthy individuals.

METHODS

In this study combinations of three BP-T loads were used to predict 1RM Smith Machine bench press strength. Additionally, we examined whether regression models developed using peak vertical bar velocity (Vpeak), rather than Vmean, provide the most accurate prediction of Smith Machine bench press 1RM. 1RM Smith Machine bench press strength was measured directly in 12 healthy regular weight trainers (body mass = 80.8 ± 5.7 kg). Two to three days later a linear position transducer attached to the collars on a Smith Machine was used to record Vmean and Vpeak during BP-T between 30 and 70% of 1RM (10% increments).

RESULTS

Repeated measures analysis of variance testing showed that the mean values for slope and ordinate intercept for the regression models at each of the load ranges differed significantly depending on whether Vmean or Vpeak were used in the prediction models (P < 0.001). Conversely, the abscissa intercept did not differ significantly between either measure of vertical bar velocity at each load range. The key finding in this study was that 1RM Smith Machine bench press strength can be determined with high relative accuracy by examining Vmean and Vpeak during BP-T over three loads, with the most precise models using Vpeak during loads representing 30, 40 and 50% of 1RM (R2  = 0.96, SSE = 4.2 kg).

CONCLUSIONS

These preliminary findings indicate that exercise programmers working with normal healthy populations can accurately predict Smith Machine 1RM bench press strength using relatively light load Smith Machine BP-T testing, avoiding the need to expose their clients to potentially injurious loads.

Relationship between the rating of perceived exertion scale and the load intensity of resistance training

Studies have reported that the load intensity of Resistance training is related to the rating of perceived exertion scale in healthy subjects. The aim of our column was to evaluate current evidence regarding the relationship between the rating of perceived exertion scale and the load intensity of resistance training.

Estimation of 1RM for knee extension based on the maximal isometric muscle strength and body composition

[Purpose] To create a regression formula in order to estimate 1RM for knee extensors, based on the maximal isometric muscle strength measured using a hand-held dynamometer and data regarding the body composition. [Subjects and Methods] Measurement was performed in 21 healthy males in their twenties to thirties. Single regression analysis was performed, with measurement values representing 1RM and the maximal isometric muscle strength as dependent and independent variables, respectively. Furthermore, multiple regression analysis was performed, with data regarding the body composition incorporated as another independent variable, in addition to the maximal isometric muscle strength. [Results] Through single regression analysis with the maximal isometric muscle strength as an independent variable, the following regression formula was created: 1RM (kg)=0.714 + 0.783 × maximal isometric muscle strength (kgf). On multiple regression analysis, only the total muscle mass was extracted. [Conclusion] A highly accurate regression formula to estimate 1RM was created based on both the maximal isometric muscle strength and body composition. Using a hand-held dynamometer and body composition analyzer, it was possible to measure these items in a short time, and obtain clinically useful results.