Specific Adaptations to 0%, 15%, 25%, and 50% Velocity-Loss Thresholds During Bench Press Training

Comparative Effects of the Free Weights and Smith Machine Squat and Bench Press: The Important Role of Specificity for Strength Adaptations

PURPOSE

Although previous studies have compared strength-training adaptations between free weights (FW) and machine-guided exercises, those studies did not use a Smith machine (SM), which most closely replicates the exercises performed with FW. Thus, the aim of the present study was to investigate the chronic effects of strength-focused, velocity-based training regimens using FW versus SM.

METHODS

Thirty-seven sport-science students (14 female) were assigned, balanced by sex and relative strength, to either an FW or SM training group. The training program lasted 8 weeks (2 sessions/wk), and participants performed 4 sets per exercise (back squat and bench press) at 70% of their 1-repetition maximum with moderate effort levels (20%-25% velocity loss). Load-velocity profile parameters (load-axis intercept, velocity-axis intercept, and area under the load-velocity relationship line), cross-sectional areas of the vastus lateralis and pectoralis major muscles, and the number of repetitions to failure in the bench-press exercise were assessed before and after the training program. Mechanical variables were assessed using both FW and SM.

RESULTS

All variables, with the exception of back-squat velocity-axis intercept (P = .124), improved in both training groups. The changes in load-axis intercept and area under the load-velocity relationship line were more pronounced when the training and testing conditions matched. Failure in the bench-press exercise and cross-sectional areas of the vastus lateralis and pectoralis major showed comparable improvements for both training groups, while velocity-axis intercept tended to improve more in the SM group.

CONCLUSIONS

The general population, unconcerned with the specificity of strength adaptations, can choose a training modality (FW or SM) based on personal preferences.

Cluster sets lead to better performance maintenance and minimize training-induced fatigue than traditional sets

Objective

The aim of this study was to examine the acute effects on mechanical, neuromuscular, metabolic, and muscle contractile responses to different set configurations in full-squat (SQ).

Methods

Twenty-two men performed three SQ sessions that consisted of 3 sets of 12 repetitions with 60% 1RM with 4 minutes inter-set rests: a) traditional set (TS): no rest within the set; b) cluster-6 (CS6): a 30 seconds intraset rest after the 6th repetition of each set; and c) cluster-2 (CS2): a 30 seconds intraset rest every 2 repetitions. Mechanical (i.e., force, velocity, and power) and electromyography (EMG) values were recorded for every repetition. A battery of tests was performed: a) tensiomyography (TMG), b) blood lactate c), countermovement jump (CMJ), d) maximal isometric SQ, and e) performance with the load that resulted in a velocity of 1 m·s-1 at baseline (V1-load). Repeated measured ANOVA analyses were used to compare the 3 protocols.

Results

As the number of intraset rests increased (TS < CS6 < CS2), mechanical performance was better maintained (p < 0.01) and EMG variables were less altered (p = 0.05). At post, CS2 and CS6 displayed lower lactate concentration, lesser reductions in CMJ height, and smaller alterations in TMG-derived variables than TS (p < 0.05).

Conclusion

The introduction of short and frequent intraset rest periods during resistance exercise alleviates training-induced fatigue, resulting in better maintenance of performance. This approach can be applied during the in-season period when minimizing fatigue is a priority.

The effect of the ketogenic diet on resistance training load management: a repeated-measures clinical trial in trained participants

BACKGROUND

The effect of low-carbohydrate high-fat dietary manipulation, such as the ketogenic diet (KD), on muscle strength assessment in resistance-training (RT) participants has focused on the one-repetition maximum test (1-RM). However, a pre-specified 1-RM value during an exercise training program disregards several confounding factors (i.e. sleep, diet, and training-induced fatigue) that affect the exerciser's "true" load and daily preparedness. We aimed to evaluate the effect of a 6-week RT program on load control-related variables in trained subjects following a KD intervention.

METHODS

Fourteen resistance-trained individuals (3F, 11 M; 30.1 [6.2] years; 174.2 [7.6] cm; 75.7 [10.8] kg; BMI 24.8 [2.1] kg·m-2) completed this single-arm repeated-measures clinical trial. Load management variables included volume load, number of repetitions, perceived exertion (RPE), movement velocity loss, and exertion index. These primary outcomes were assessed weekly before, during, and at the end of a 6-week RT program that included traditional RT exercises (bench press, femoral lying down, lat pulldown, leg extension, and back squat).

RESULTS

There was a significant difference in RPE between weeks (p = 0.015, W = 0.19) with a slight trend in decreasing RPE. We found differences in the volume load per week (p < 0.001; W = 0.73 and p < 0.001, W = 0.81, respectively), with an increase in the last weeks. In the control of the load based on movement velocity, we did not find significant differences between weeks (p = 0.591, W = 0.06), although significant differences were found in the effort index (p = 0.026, W = 0.17).

CONCLUSIONS

A KD diet in recreational strength participants does not appear to lead to performance losses during a RT program aimed at improving body composition. However, the lack of adherence and familiarity with the ketogenic diet must be considered specially during first weeks.

Impact of Generalized Versus Individualized Load-Velocity Equations on Velocity-Loss Magnitude in Bench-Press Exercise: Mixed-Model and Equivalence Analysis

PURPOSE

This study analyzed the influence of 2 velocity-based training-load prescription strategies (general vs individual load-velocity equations) on the relationship between the magnitude of velocity loss (VL) and the percentage of repetitions completed in the bench-press exercise.

METHODS

Thirty-five subjects completed 6 sessions consisting of performing the maximum number of repetitions to failure against their 40%, 60%, and 80% of 1-repetition maximum (1RM) in the Smith machine bench-press exercise using generalized and individualized equations to adjust the training load.

RESULTS

A close relationship and acceptable error were observed between percentage of repetitions completed and the percentage of VL reached for the 3 loading magnitudes and the 2 load-prescription strategies studied (R2 from .83 to .94; standard error of the estimate from 7% to 10%). A simple main effect was observed for load and VL thresholds but not for load-prescription strategies. No significant interaction effects were revealed. The 40% and 60% 1RM showed equivalence on data sets and the most regular variation, whereas the 80% 1-repetition maximum load showed no equivalence and more irregular variation.

CONCLUSION

These results suggest that VL is a useful variable to predict percentage of repetitions completed in the bench-press exercise, regardless of the strategy selected to adjust the relative load. However, caution should be taken when using heavy loads.

Effects of Velocity Loss During Bench-Press Training With Light Relative Loads

PURPOSE

This study explored the effects of 4 bench-press (BP) training programs with different velocity-loss (VL) thresholds (0%, 15%, 25%, and 50%) on strength gains and neuromuscular adaptations.

METHODS

Forty-six resistance-trained men (22.8 [4.4] y) were randomly assigned into 4 groups that differed in the VL allowed within the set: 0% (VL0), 15% (VL15), 25% (VL25), and 50% (VL50). Training loads (40%-55% 1-repetition maximum), frequency (2 sessions/wk), number of sets (3), and interset recovery (4 min) were identical for all groups. Participants completed the following tests before and after an 8-week (16-session) BP training program: (1) maximal isometric test, (2) progressive loading test, and (3) fatigue test in the BP exercise. During all tests, triceps brachii muscle electromyography was assessed.

RESULTS

After completing the resistance-training program, no significant group × time interactions were noticed for isometric and dynamic BP strength variables. The dose-response relationship exhibited an inverted U-shaped relationship pattern, with VL25 showing the greatest effect sizes for almost all strength variables analyzed. The total number of repetitions performed during the training program increased as the VL magnitude increased.

CONCLUSIONS

The group that trained with high VL threshold (50%), which performed a total of 876 repetitions, did not experience additional strength gains compared with those experienced by the 0%, 15%, and 25% of VL groups, which performed significantly fewer repetitions (48, 357, and 547, respectively). These findings suggest that when light loads (40%-55% 1-repetition maximum) are used, low and moderate VL thresholds (0%-25%) provide a higher training efficiency.

Exploring the Dose-Response Relationship Between Estimated Resistance Training Proximity to Failure, Strength Gain, and Muscle Hypertrophy: A Series of Meta-Regressions

BACKGROUND

The proximity to failure in which sets are terminated has gained attention in the scientific literature as a potentially key resistance training variable. Multiple meta-analyses have directly (i.e., failure versus not to failure) or indirectly (e.g., velocity loss, alternative set structures) evaluated the effect of proximity to failure on strength and muscle hypertrophy outcomes categorically; however, the dose-response effects of proximity to failure have not been analyzed collectively in a continuous manner.

OBJECTIVE

To meta-analyze the aforementioned areas of relevant research, proximity to failure was quantified as the number of repetitions in reserve (RIR). Importantly, the RIR associated with each effect in the analysis was estimated on the basis of the available descriptions of the training interventions in each study. Data were extracted and a series of exploratory multilevel meta-regressions were performed for outcomes related to both strength and muscle hypertrophy. A range of sensitivity analyses were also performed. All models were adjusted for the effects of load, method of volume equating, duration of intervention, and training status.

RESULTS

The best fit models for both strength and muscle hypertrophy outcomes demonstrated modest quality of overall fit. In all of the best-fit models for strength, the confidence intervals of the marginal slopes for estimated RIR contained a null point estimate, indicating a negligible relationship with strength gains. However, in all of the best-fit models for muscle hypertrophy, the marginal slopes for estimated RIR were negative and their confidence intervals did not contain a null point estimate, indicating that changes in muscle size increased as sets were terminated closer to failure.

CONCLUSIONS

The dose-response relationship between proximity to failure and strength gain appears to differ from the relationship with muscle hypertrophy, with only the latter being meaningfully influenced by RIR. Strength gains were similar across a wide range of RIR, while muscle hypertrophy improves as sets are terminated closer to failure. Considering the RIR estimation procedures used, however, the exact relationship between RIR and muscle hypertrophy and strength remains unclear. Researchers and practitioners should be aware that optimal proximity to failure may differ between strength and muscle hypertrophy outcomes, but caution is warranted when interpreting the present analysis due to its exploratory nature. Future studies deliberately designed to explore the continuous nature of the dose-response effects of proximity to failure in large samples should be considered.

Does Fatigue Affect the Perception of Velocity Accuracy During Resistance Training?

ABSTRACT

Romagnoli, R and Piacentini, MF. Does fatigue affect the perception of velocity accuracy during resistance training? J Strength Cond Res 38(7): 1243-1247, 2024-The purpose of this study was to investigate whether perception of barbell velocity (PV) is affected by fatigue induced by 2 different training protocols. Twenty-two subjects were randomly divided into 2 groups: 10% velocity loss group (VL10) and repetitions to failure group (EX). Both protocols included 5 sets at 75% 1 repetition maximum but differed in the number of repetitions performed (Reps). Perception of barbell velocity was assessed in the back squat exercise during a test with 3 blinded loads (heavy, medium, light) 1 day rested (REST) and 1 day immediately following 1 of the 2 designated training protocols (POST). The accuracy of the PV was analyzed by calculating the delta score (ds), that is, the difference between perceived velocity (Vp) and real velocity of the barbell (Vr). During training, each group performed significantly different Reps per set (VL10: 3.9 ± 1.4; EX: 13.8 ± 6.3, p < 0.001) and consequently reported different levels of perceived exertion and repetitions in reserve ( p < 0.001). Real velocity and ds did not change between REST and POST-VL10 conditions at all loads. Although a significant decrease in Vr was found at light and medium loads ( p < 0.05) between REST and POST in the EX-Group, no significant differences were detected in the ds. These results demonstrate that Vp is a stable parameter on which practitioners can base their training despite different levels of fatigue.

Fatigue and Metabolic Responses during Repeated Sets of Bench Press Exercise to Exhaustion at Different Ranges of Motion

This study compared the acute effects of different ranges of motion (ROM) on fatigue and metabolic responses during repeated sets of bench press exercise. Ten resistance trained men performed three sets to momentary failure with two-min rest intervals at three different ROM: full ROM (FULL), and partial ROM in which the barbell was moved either at the bottom half (BOTTOM) or the top half (TOP) of the full barbell vertical displacement. In TOP, a higher load was lifted, and a higher total number of repetitions was performed compared to FULL and BOTTOM (130 ± 17.6 vs. 102.5 ± 15.9 vs. 98.8 ± 17.5 kg; 55.2 ± 9.8, 32.2 ± 6.5 vs. 49.1 ± 16.5 kg, respectively p < 0.01). Work per repetition was higher in FULL than TOP and BOTTOM (283 ± 43 vs. 205 ± 32 vs. 164 ± 31 J/repetition, p < 0.01). Mean barbell velocity at the start of set 1 was 21.7% and 12.8% higher in FULL compared to TOP and BOTTOM, respectively. The rate of decline in mean barbell velocity was doubled from set 1 to set 3 (p < 0.01) and was higher in FULL than both TOP and BOTTOM (p < 0.001). Also, the rate of mean barbell velocity decline was higher in BOTTOM compared to TOP (p = 0.045). Blood lactate concentration was similarly increased in all ROM (p < 0.001). Training at TOP ROM allowed not only to lift a higher load, but also to perform more repetitions with a lower rate of decline in mean barbell velocity. Despite the lower absolute load and work per repetition, fatigue was higher in BOTTOM than TOP and this may be attributed to differences in muscle length.

Inter-repetition Rest Impact on Percentage of Repetition Completed at Certain Velocity Loss

This study examined the impact of different inter-repetition rest (IRR) configurations (zero seconds [IRR0], three seconds [IRR3], and self-selected less than five seconds [SSIRR]) on estimating the number of repetitions (Nrep) and the percentage of completed repetitions relative to the maximum number of repetitions possible to failure (%rep) after reaching 10%, 20%, and 30% velocity loss thresholds (VLT). Eighteen men completed three sessions, each with a different IRR configuration, separated by 48-72 hours. Single sets of repetitions to momentary muscular failure were performed against 65%, 75%, and 85% of the one-repetition maximum during free-weight back squat and bench press exercises. No significant differences were reported between IRR configurations for the Nrep (P≥0.089) and %rep (P≥0.061), except for %rep after reaching the 20-30%VLT against 65%1RM and the 10-20%VLT against 75%1RM in the bench press exercise (P≤0.048). Additionally, both Nrep and %rep exhibited high interindividual variability (between-subject CV=14-79%) across the different IRR configurations. The individual %rep-%VLT relationships were slightly stronger than the general %rep-%VLT relationships (median R 2 =0.914-0.971 vs. 0.698-0.900). Overall, regardless of the IRR configuration, this novel velocity-based approach does not guarantee the same effort levels across subjects in the free-weight back squat and bench press sets.

Similar muscle hypertrophy following eight weeks of resistance training to momentary muscular failure or with repetitions-in-reserve in resistance-trained individuals

This study examined the influence of resistance training (RT) proximity-to-failure, determined by repetitions-in-reserve (RIR), on quadriceps hypertrophy and neuromuscular fatigue. Resistance-trained males (n = 12) and females (n = 6) completed an 8-week intervention involving two RT sessions per week. Lower limbs were randomised to perform the leg press and leg extension exercises either to i) momentary muscular failure (FAIL), or ii) a perceived 2-RIR and 1-RIR, respectively (RIR). Muscle thickness of the quadriceps [rectus femoris (RF) and vastus lateralis (VL)] and acute neuromuscular fatigue (i.e., repetition and lifting velocity loss) were assessed. Data was analysed with Bayesian linear mixed-effect models. Increases in quadriceps thickness (average of RF and VL) from pre- to post-intervention were similar for FAIL [0.181 cm (HDI: 0.119 to 0.243)] and RIR [0.182 cm (HDI: 0.115 to 0.247)]. Between-protocol differences in RF thickness slightly favoured RIR [-0.036 cm (HDI: -0.113 to 0.047)], but VL thickness slightly favoured FAIL [0.033 cm (HDI: -0.046 to 0.116)]. Mean volume was similar across the RT intervention between FAIL and RIR. Lifting velocity and repetition loss were consistently greater for FAIL versus RIR, with the magnitude of difference influenced by the exercise and the stage of the RT intervention.

Next steps to advance general physical activity recommendations towards physical exercise prescription: a narrative review

Physical inactivity is a major health concern, associated with the development of several non-communicable diseases and with an increased mortality rate. Therefore, promoting active lifestyles has become a crucial public health necessity for enhancing overall health and quality of life. The WHO guidelines for physical activity (PA) present valuable contributions in this respect; however, we believe that greater specificity should be added or complemented towards physical exercise (PE) testing, prescription and programming in future recommendations. In this review article, we suggest simple and practical tools accessible to the entire population to improve the specificity of this approach, highlighting aspects of PE programming used by trained subjects. By adopting these suggestions, exercise professionals, clinicians and physical trainers can optimise the current general PA recommendations towards PE prescription to improve fitness status and encourage PE adherence in the general population.

Influence of Resistance Training Proximity-to-Failure on Skeletal Muscle Hypertrophy: A Systematic Review with Meta-analysis

BACKGROUND AND OBJECTIVE

This systematic review with meta-analysis investigated the influence of resistance training proximity-to-failure on muscle hypertrophy.

METHODS

Literature searches in the PubMed, SCOPUS and SPORTDiscus databases identified a total of 15 studies that measured muscle hypertrophy (in healthy adults of any age and resistance training experience) and compared resistance training performed to: (A) momentary muscular failure versus non-failure; (B) set failure (defined as anything other than momentary muscular failure) versus non-failure; or (C) different velocity loss thresholds.

RESULTS

There was a trivial advantage for resistance training performed to set failure versus non-failure for muscle hypertrophy in studies applying any definition of set failure [effect size=0.19 (95% confidence interval 0.00, 0.37), p=0.045], with no moderating effect of volume load (p=0.884) or relative load (p=0.525). Given the variability in set failure definitions applied across studies, sub-group analyses were conducted and found no advantage for either resistance training performed to momentary muscular failure versus non-failure for muscle hypertrophy [effect size=0.12 (95% confidence interval -0.13, 0.37), p=0.343], or for resistance training performed to high (>25%) versus moderate (20-25%) velocity loss thresholds [effect size=0.08 (95% confidence interval -0.16, 0.32), p=0.529].

CONCLUSION

Overall, our main findings suggest that (i) there is no evidence to support that resistance training performed to momentary muscular failure is superior to non-failure resistance training for muscle hypertrophy and (ii) higher velocity loss thresholds, and theoretically closer proximities-to-failure do not always elicit greater muscle hypertrophy. As such, these results provide evidence for a potential non-linear relationship between proximity-to-failure and muscle hypertrophy.