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This study examined the effects of resistance training combined with whey protein and leucine blends on muscular strength (1-RM), endurance (repetitions to failure [RTF]), cross-sectional area (CSA), perceived exertion (RPE), and body mass (BM). Thirty-nine men (age = 20.6 ± 1.5 yrs) were randomly assigned to 1 of 3 Groups: (a) 1 dose of 40 g of whey protein and 6.2 g of total leucine (1PRO+L, n = 13); (b) 2 doses of 20 g of whey protein and 6.2 g of total leucine per dose (2PRO+L, n = 12); or (c) placebo (PLA, n = 14). The dependent variables were assessed before and after 8 weeks of high-intensity resistance training 3 d·wk-1. Mixed factorial ANOVAs revealed significant (P < 0.001) increases in BP and LE 1-RM and RTF, VL CSA, a reduction in RPE, and no change in BM (P > 0.05), with no between Group differences. Individual analyses indicated that a greater proportion of the 1PRO+L Group exceeded the minimal important difference for LE 1-RM and RTF compared to those in the 2PRO+L and PLA Groups (P < 0.05). No other differences were observed for the individual responses. These findings indicate that 40 g of whey protein with 6.2 g of total leucine increased LE 1-RM and RTF more than 2 doses of 20 g of whey protein with 6.2 g of total leucine or PLA. [ABSTRACT FROM AUTHOR]

This study examined the effects of sustained, isometric forearm flexion tasks anchored to ratings of perceived exertion of 2 (RPE2FT) and 8 (RPE8FT) on the patterns of fatigue-induced changes in torque and neuromuscular responses, time to task failure (TTF), performance fatigability (% decline in maximal voluntary isometric contraction [MVIC]), and perceived factors that contributed to task termination. Twelve men (mean ± SD: age = 20.9 ± 2.2 yrs) performed MVICs before and after the tasks and completed post-test questionnaires (PTQ). Data were analyzed using polynomial regression analyses, dependent t-tests, Spearman's rank order correlations, and Wilcoxon signed rank tests. The RPE8FT had greater (p < 0.001) performance fatigability than the RPE2FT, despite no difference (p > 0.05) in TTF. During both tasks, there were significant (p ≤ 0.05) composite linear decreases for torque, electromyographic amplitude, and neuromuscular efficiency, and substantial individual variability in the neuromuscular responses. There were no significant (p > 0.05) associations among the perceived factors and TTF or performance fatigability. Thus, there were RPE-specific differences in performance fatigability, but not TTF or the composite patterns of changes in torque and neuromuscular responses. In addition, in most cases, the individual neuromuscular, but not torque, patterns of responses were RPE-specific. Furthermore, the perceived factors assessed by the PTQ were not related to TTF or performance fatigability. [ABSTRACT FROM AUTHOR]

This study examined the torque and neuromuscular responses following sustained, isometric, forearm flexion tasks anchored to 2 ratings of perceived exertion (RPE). Nine men (mean ± SD: age = 21.0 ± 2.4 years; height = 179.5 ± 5.1 cm; body mass = 79.6 ± 11.4 kg) completed maximal voluntary isometric contractions (MVIC) before and after sustained, isometric, forearm flexion tasks to failure anchored to RPE = 2 and RPE = 8. The amplitude (AMP) and mean power frequency (MPF) of the electromyographic (EMG) signal were recorded from the biceps brachii. Normalized torque was divided by normalized EMG AMP to calculate neuromuscular efficiency (NME). A dependent t-test was used to assess the mean difference for time to task failure (TTF). Repeated-measures analysis of variances was used to compare mean differences for MVIC and normalized neuromuscular parameters. There was no significant difference in TTF between RPE = 2 and RPE = 8 (p = 0.713). The MVIC decreased from pretest to posttest at RPE = 2 (p = 0.009) and RPE = 8 (p = 0.003), and posttest MVIC at RPE = 8 was less than that at RPE = 2 (p < 0.001). In addition, NME decreased from pretest to posttest (p = 0.008). There was no change in normalized EMG AMP or EMG MPF (p > 0.05). The current findings indicated that torque responses were intensity specific, but TTF and neuromuscular responses were not. Furthermore, normalized EMG AMP and EMG MPF remained unchanged but NME decreased, likely due to peripheral fatigue and excitation-contraction coupling failure. Thus, this study provides information regarding the neuromuscular responses and mechanisms of fatigue associated with tasks anchored to RPE, which adds to the foundational understanding of the relationship between resistance exercise and the perception of fatigue. [ABSTRACT FROM AUTHOR]

(1) There is growing concern surrounding the adverse effects of prolonged sitting on health, yet its impact on post-exercise recovery remains relatively unexplored. This study aimed to better understand the potential influence of habitual prolonged sitting on recovery time and the unfavorable impact prolonged sitting may have on time to recovery, as assessed by muscle damage and inflammatory markers and an isokinetic dynamometer. (2) Nine college-age men (mean age ± SD = 22.1 ± 3.1 years, body mass = 80.9 ± 15.7 kg, height = 171 ± 9.0 cm, Body Mass Index (BMI) = 27.6 ± 4.9 kg·m2) participated in an exhaustive exercise protocol. Creatine Kinase (CK), Myoglobin (Mb), C-Reactive Protein (CRP), White Blood Cell Count (WBC), Peak Torque (PT), and muscle soreness were measured at baseline and 0, 24, 48, and 72 h post-exercise. Dietary and exercise logs were maintained during the 5-day testing procedure. (3) No significant differences were observed in muscle damage markers (CK [p = 0.068] and Mb [p = 0.128]), inflammatory markers (CRP [p = 0.814] and WBC [p = 0.140]), or PT [p = 0.255]) at any time point. However, a significant positive correlation was found between daily sitting time and the percent increase in CK concentration from 0 h to 72 h (r = 0.738, p = 0.023). Strong correlations were also noted between prolonged sitting and percent change in Mb concentration at 48 h (r = 0.71, p = 0.033) and 72 h (r = 0.889, p = 0.001). There was a significant two-way interaction for time × velocity (p = 0.043) for PT with a simple main effect for time at 60°· s − 1 (p = 0.038). No significant associations were detected between daily carbohydrate or protein intake and recovery markers (p > 0.05). (4) The findings suggest minimizing daily sitting time may expedite and potentially aid muscle recovery after an intense exercise bout, although further research is warranted to validate these findings. [ABSTRACT FROM AUTHOR]

The purpose of this study was to examine the effects of high-intensity, eccentric-only muscle actions of the leg extensors on (a) serum biomarkers of collagen degradation (hydroxyproline [HYP] and C-terminal telopeptide of type I collagen [C1M]) and synthesis (pro-c1a1) and (b) the time course of changes in maximal voluntary isometric contraction (MVIC) and ratings of muscle soreness after the eccentric-only exercise bout. Twenty-five recreationally active men (mean ± SD: age = 21.2 ± 2.0 years) completed 5 sets of 10 bilateral, eccentric-only dynamic constant external resistance muscle actions of the leg extensors at a load of 110% of their concentric leg extension 1 repetition maximum. Analysis of variances (p < 0.05) and a priori planned pairwise comparisons using Bonferroni corrected (p < 0.0167) paired t tests were used to examine mean changes in blood biomarkers from baseline to 48 hours postexercise as well as in MVIC and soreness ratings immediately, 24 hours, and 48 hours postexercise. There were increases in HYP (3.41 ± 2.37 to 12.37 ± 8.11 µg⋅ml-1; p < 0.001) and C1M (2.50 ± 1.05 to 5.64 ± 4.89 µg⋅L-1; p = 0.003) from preexercise to 48 hours postexercise, but no change in pro-c1 α1. Maximal voluntary isometric contraction declined immediately after the exercise bout (450.44 ± 72.80 to 424.48 ± 66.67 N-m; p = 0.002) but recovered 24 hours later, whereas soreness was elevated immediately (6.56 ± 1.58; p < 0.001), 24 hours (3.52 ± 1.53; p < 0.001), and 48 hours (2.60 ± 1.32; p = 0.001) postexercise. The eccentric-only exercise bout induced increases in collagen degradation but had no effect on collagen synthesis. These findings provide information for clinicians to consider when prescribing exercise after an acute injury or surgery. [ABSTRACT FROM AUTHOR]

The Effects of Anchor Scheme and Sex on Performance Fatigability and Neuromuscular Responses Following Sustained, Isometric Forearm Flexion Tasks to Failure. JEPonline 2023;26(3):69-92. The purpose of this study was to examine the effects of anchor scheme and sex on time to task failure (TTF), maximal voluntary isometric contraction (MVIC) assessments, and neuromuscular responses following sustained, isometric forearm flexion tasks. Eight males and 8 females performed MVICs before and after sustained tasks anchored to an RPE = 8 (RPEFT) and torque (TRQFT). The amplitude (AMP) and frequency (MPF) of the electromyographic (EMG) and mechanomyographic (MMG) signals were recorded from the biceps brachii. Mixed factorial ANOVAs were used to examine the mean differences in the MVIC, as well as the normalized neuromuscular parameters. For the TTF, the RPEFT was longer (P = 0.003) than the TRQFT. There were parallel fatigue-induced decreases in MVIC (P < 0.001) and EMG AMP (P = 0.023), while MMG AMP increased (P = 0.002), regardless of anchor scheme or sex. However, the MPF for EMG and MMG remained unchanged. [ABSTRACT FROM AUTHOR]

Abstract: Roberts, TD, Smith, RW, Arnett, JE, Ortega, DG, Schmidt, RJ, and Housh, TJ. Cross-validation of equations for estimating 1 repetition maximum from repetitions to failure for the bench press and leg extension. J Strength Cond Res 39(2): e96-e105, 2025-Eighteen previously published equations (EQs) that estimate 1 repetition maximum (1RM) from repetitions to failure (RTF) were cross-validated for the bench press (BP) and leg extension (LE) movements. Forty-three recreationally active men (age: 20.58 ± 1.47 years; body mass [BM]: 81.66 ± 13.65 kg) completed a 1RM test and RTF at 80% of the 1RM test for the LE, and 39 of the 43 men (age: 20.61 ± 1.48 years; BM: 83.58 ± 12.73 kg) completed the same tests for the BP. The EQs were categorized as generic (the source did not indicate its applicability for a specific movement) or movement-specific (BP-specific and LE-specific EQs). The generic EQs were cross-validated for both movements, whereas the BP-specific and LE-specific EQs were cross-validated for their respective movements only. The cross-validation criteria included calculations of the constant error (CE) (mean differences between estimated and measured 1RM), Pearson Correlation Coefficient, standard error of the estimate, and total error. The level of significance was set at p ≤ 0.05. After the initial cross-validation analyses of the previously published EQs, the most accurate EQs were modified by subtracting their cross-validation CE from the original EQ to improve their accuracy for estimating BP and LE 1RM by eliminating systematic error. The modified EQs were then cross-validated using the same statistical procedures. Based on the cross-validation analyses, we recommend the following EQs: BP 1RM = (RTF 0.1 × weight) + 1.49 and LE 1RM = (RTF 0.1 × weight) + 1.06 using weights that result in 4-10 RTF., (Copyright © 2024 National Strength and Conditioning Association.)

Objectives: To examine the effects of joint angle (JA) on maximal voluntary isometric contractions (MVIC) and neuromuscular responses following a sustained, isometric forearm flexion task anchored to a rating of perceived exertion (RPE) of 8 (RPE=8)., Methods: Nine women (age: 20.7±2.9 yrs; height: 168.8±7.2 cm; body mass: 66.3±6.8 kg) performed 2,3s forearm flexion MVICs at JAs of 75°, 100°, and 125° prior to and following a sustained, isometric forearm flexion task anchored to RPE=8 to task failure (torque reduced to zero) at JA100. Electromyographic (EMG) and mechanomyographic (MMG) signals were recorded from the biceps brachii., Results: The MVIC at JA100 (collapsed across Time) was significantly greater (p<0.05) than JA75 and JA125. The pre-test MVIC was significantly greater (p<0.001) than the post-test. For EMG amplitude (AMP) and EMG mean power frequency (MPF), pre-test values were significantly greater (p<0.05) than the post-test values, with no differences between JAs. For MMG AMP and MMG MPF, there were no significant (p>0.05) differences between Time or JAs. Pre-test neuromuscular efficiency (normalized MVIC/normalized EMG AMP) was significantly greater (p=0.005) than post-test., Conclusion: Following a sustained, isometric forearm flexion task anchored to RPE=8 at JA100, the fatigue-induced MVIC and neuromuscular responses were not affected by JA., Competing Interests: The authors have no conflict of interest.