Time Under Tension Research Articles

Assessment of the Impact of Sensor-Based Ischemic Preconditioning with Different Cycling Periods on Upper Limb Strength in Bodybuilding Athletes.

Objective: This study designed experiments to explore the effects of ischemic preconditioning (IPC) intervention with different cycling periods on the upper limb strength performance of college male bodybuilding athletes. Methods: Ten bodybuilding athletes were recruited for a randomized, double-blind, crossover experimental study. All subjects first underwent pre-tests with two sets of exhaustive bench presses at 60% of their one-repetition maximum (1RM) to assess upper limb strength performance. They then experienced three different IPC intervention modes (T1: 1 × 5 min, T2: 2 × 5 min, T3: 3 × 5 min), as well as a non-IPC intervention mode (CON), followed by a retest of the bench press. An Enode pro device was used to record the barbell's velocity during the bench press movement (peak velocity (PV), mean velocity (MV)); power (peak power (PP), mean power (MP)); and time under tension (TUT) to evaluate upper limb strength performance. Results: PV values: T1 showed significant increases compared to pre-tests in the first (p = 0.02) and second (p = 0.024) tests, and were significantly greater than the CON (p = 0.032); T2 showed a significant increase in PV in the first test (p = 0.035), with no significant differences in other groups. MV values: T1 showed a significant increase in MV in the first test compared to the pre-test (p = 0.045), with no significant differences in other groups. PP values: T1 showed a highly significant increase in PP in the first test compared to the pre-test (p = 0.001), and was significantly higher than the CON (p = 0.025). MP values: T1 showed highly significant increases in MP in both the first (p = 0.004) and second (p = 0.003) tests compared to the pre-test; T2 showed a highly significant increase in MP in the first test (p = 0.039) and a significant increase in the second test (p = 0.039). T1's MP values were significantly higher than the CON in both tests; T2's MP values were significantly higher than the CON in the first (p = 0.005) and second (p = 0.024) tests. TUT values: T1 showed highly significant increases in TUT in the first (p < 0.001) and second (p = 0.002) tests compared to the pre-test, and were significantly higher than the CON. Conclusions: (1) Single-cycle and double-cycle IPC interventions both significantly enhance upper limb strength performance, significantly improving the speed and power in exhaustive bench press tests, with the single-cycle IPC intervention being more effective than the double-cycle IPC intervention. (2) The triple-cycle IPC intervention does not improve the upper limb strength performance of bodybuilding athletes in exhaustive bench presses.

Low adherence to prescribed time under tension in elastic band resistance training in older adults. An observational study

Time under tension (TUT) is an important variable in resistance training (RT). A stretch sensor (Bandcizer) attached to an elastic band during RT can quantify TUT reliably. ObjectiveTo explore adherence to prescribed TUT for elastic band RT with the Bandcizer during supervised and unsupervised RT at different time points. Methods22 men and women (66.2 ± 2.1 years) performed one supervised and two unsupervised sessions weekly of elastic band RT for the upper and lower extremities with the Bandcizer during a 25-week period. Prescribed TUT was 4 s/repetition. Bandcizer data were extracted from week: 1, 8, and median 24. The effects of time point and supervision on adherence (%) to TUT and number of repetitions were analyzed by Two-way ANOVA. ResultsDuring supervised sessions, adherence to prescribed TUT was 79 ± 4%, 60 ± 4%, and 53 ± 5% in week: 1, 8, and median 24, respectively (p < 0.001). There was no difference in adherence between supervised and unsupervised sessions at any time points. Adherence to the prescribed number of repetitions in each training session was close to 100%. ConclusionAdherence to prescribed TUT was low during both supervised and unsupervised, home-based elastic band RT and decreased over time despite weekly supervision. Our results highlight the need to focus on TUT when planning and implementing elastic band resistance training in retirement age individuals.

Time under tension and mechanical variables in the bench press exercise at different rest intervals

Purpose: To analyze the behavior of time under tension (TUT), total work (TW), power (PW), mean velocity (MV), and number of repetitions (NR) during the bench press exercise with distinct rest intervals. Methods: Twenty-one wrestling athletes (body mass: 81.27 ± 14.25kg; height: 1.74 ± 0.07m) completed 5 sets, each consisting of a maximum of 10 repetitions, with either a 1-minute rest interval (RI1) or a 3-minute rest interval (RI3). Results: TUT was higher in RI3 when compared to RI1 in set 5 (p&lt;0.001). NR was higher in RI3 compared to RI1 in set 3 (p=0.016), set 4 (p=0.021), and set 5 (p&lt;0.001). TW was higher in RI3 compared to RI1 in set 3 (p=0.005), set 4 (p=0.007), and set 5 (p&lt;0.001). MV was higher in RI3 compared to RI1 in set 4 (p=0.029) and set 5 (p&lt;0.001). PW was higher in RI3 compared to RI1 in set 4 (p=0.044) and set 5 (p&lt;0.001). Conclusion: The behavior of consecutive sets with a similar number of repetitions but with an increase in TUT or sets with a similar TUT but with a lower number of repetitions were found. Third set appears to be a point of performance reduction worth considering depending on the exercise's goal. Keywords: time under tension; number of repetitions; bench press; rest interval between sets; mechanical variables.

Effect of Step Load Based on Time under Tension in Hypoxia on the ACL Pre-Operative Rehabilitation and Hormone Levels: A Case Study.

The aim of the study was to determine the effect of step load in hypoxia on the effectiveness of preoperative rehabilitation (PR) and hormone levels based on a case study. Introduction: We assessed the impact of variables such as rate of movement and time under tension (TUT) in normobaric hypoxia on the levels of growth hormone (GH), insulin-like growth factor 1 (IGF-1), and erythropoietin (EPO). Additionally, the impact of step load on the hypertrophy and strength of knee extensors and flexors was assessed. Methods: The work uses a case study, the research subject of which was a 23-year-old female professional handball player. The tests included an isokinetic assessment of the peak torque of knee extensors and flexors as well as body composition analysis. Results: The results showed a more than (10.81-fold) increase in GH after the microcycle with time under tension (TUT). The deficit between the lower limbs was also reduced. Conclusions: Using a hypoxic environment based on an appropriate altitude, combined with changes such as a short rest break between sets and a controlled tempo of movement with an eccentric phase, TUT may offer an alternative to the PR process, especially among athletes who care about fast RTS.

Acute effects of different number of sets and non-equalized volume on muscle thickness, peak force, and physical performance in recreationally-trained participants

The purpose of this study was to measure the acute effects of resistance training (RT) protocols with a different number of sets and non-equalized volume on muscle thickness, peak force, and physical performance in recreationally-trained participants. Fifteen participants performed the unilateral biceps curl exercise in four different RT protocols (G4: 4 sets of 10RM, G8: 8 sets of 10RM, G12: 12 sets of 10RM, and G16: 16 sets of 10RM). The average number of repetitions (ANR), the total number of repetitions (TNR), time under tension (TUT), muscle thickness (MT), peak force (PF), and rating of perceived exertion (sRPE) were measured pre-test and post-test. ANOVAs were used to test differences between all dependent variables. For ANR, there were differences between G4xG8, G4xG12, and G4xG16 and between RT protocols for TNR (p&lt;0.05). There were differences for all RT protocols and between G12 and G4, G8, and G16 for TUT (p&lt;0.05). MT increased and PF decreased for all RT protocols (p&lt;0.001). In conclusion, G8, G12, and G16 showed lower ANR than G4, TNR increased with increasing sets, and TUT increased in all RT protocols. PF decreased with increasing sets and all RT protocols increased MT. The sRPE was similar between RT protocols.

Influence of different recovery intervals on time under tension, total training volume, and fatigue index in horizontal bench press exercise in young male wrestling athletes.

The recovery interval (RI) seems to be a variable closely related to the training volume since it can determine the performance after this rest time. This study investigated the influence of different recovery intervals on time under tension (TUT), total training volume (TTV), and Fatigue Index (FI) in the horizontal bench press exercise. Eighteen male wrestling athletes underwent three visits: 1st) performed the 10-repetition maximum (10RM) test; 2nd and 3rd) performed 5 sets of up to 10 repetitions with 1 minute (RI1) and 3 minutes (RI3) of passive RI with randomized entry. TUT, number of repetitions, TTV and FI data were collected or calculated. TUT was lower in sets 5 (P<0.001) for RI1 when compared to RI3, with no significant difference for the other 4 sets. The number of repetitions for RI1 was lower when compared to RI3 in sets 3 (P=0.018), 4 (P=0.023), and 5 (P<0.001), with no significant difference in sets 1 and 2. The FI was significantly higher for RI1 (P<0.001); however, TTV was significantly higher for RI3 (P=0.007). Different RI influenced the TUT and the number of repetitions along 5 sets in the horizontal bench press exercise. Moreover, these two variables showed different behavior when compared under the same condition (RI1 or RI3), especially after the third set. Using longer RI demonstrated a greater ability to maintain TTV and less negative effect of fatigue in young male wrestling athletes.

The Ultimate Guide for Selecting Repetition Tempos

Apply it! By reading this article, you will learn: • Repetition tempo, which is sometimes referred to as repetition duration, describes movement velocity during eccentric, isometric, and concentric phases of one repetition. Thus, repetition tempo plays a major role in set duration, which is commonly referred to as time under tension (TUT). • When a general population client is training for hypertrophy, the effective duration range for one repetition is 0.5 to 8 seconds. The key is making sure your client is training close to momentary muscular failure. When strength is the primary goal, there is evidence that repetition durations of less than 1 to 20 seconds are effective. Although power can be improved with a variety of tempos, a 2-second eccentric duration followed by a maximal speed concentric duration (i.e., “X”) is the most effective. • For those working with elderly patients, strength, power, and physical function can be improved with 3/3- and 3/X-second tempos, but the latter is most effective. • For those working with patients in cardiac rehabilitation or patients with cardiovascular disease, it is important to keep TUT short, which is accomplished by using faster repetition tempos (e.g., 1/1 vs. 2/2 seconds).

Analysis of Time Under Tension in Bench Press Exercise in Recreationally Trained Individuals: A Systematic Review

ABSTRACT This study aimed to analyze the time under tension (TUT) behavior in the bench press exercise performance in recreationally trained individuals. A systematic review was performed based on the PRISMA recommendations and registered on PROSPERO (CRD42022301830). MEDLINE (PubMed), Scopus, SPORTDiscus, and Lilacs (BVS) databases were consulted with the terms (resistance training [Title/Abstract]) OR (strength training [Title/Abstract]) AND (time under tension [Title/Abstract]). Cohort studies that analyzed the TUT in the bench press exercise in individuals with experience in resistance training were included. We used the Critical Appraisal Skills Program tool to analyze the methodological quality of the included studies. Thirteen studies met the inclusion criteria. The total number of participants was 215 individuals (179 men and 36 women). TUT was analyzed from the manipulation of each study variable. The behavior of the TUT in the bench press exercise varies according to the training protocol and method used. The TUT and the number of repetitions can vary to quantify the training volume.

The Need for Eccentric Speed: A Narrative Review of the Effects of Accelerated Eccentric Actions During Resistance-Based Training.

Eccentric training as a method to enhance athletic performance is a topic of increasing interest to both practitioners and researchers. However, data regarding the effects of performing the eccentric actions of an exercise at increased velocities are limited. This narrative review aimed to provide greater clarity for eccentric methods and classification with regard to temporal phases of exercises. Between March and April 2021, we used key terms to search the PubMed, SPORTDiscus, and Google Scholar databases within the years 1950-2021. Search terms included 'fast eccentric', 'fast velocity eccentric', 'dynamic eccentric', 'accentuated eccentric loading', and 'isokinetic eccentric', analysing both the acute and the chronic effects of accelerated eccentric training in human participants. Review of the 26 studies that met the inclusion criteria identified that completing eccentric tempos of < 2s increased subsequent concentric one repetition maximum performance, velocity, and power compared with > 4s tempos. Tempos of > 4s duration increased time under tension (TUT), whereas reduced tempos allowed for greater volume to be completed. Greater TUT led to larger accumulation of blood lactate, growth hormone, and testosterone when volume was matched to that of the reduced tempos. Overall, evidence supports eccentric actions of < 2s duration to improve subsequent concentric performance. There is no clear difference between using eccentric tempos of 2-6s if the aim is to increase hypertrophic response and strength. Future research should analyse the performance of eccentric actions at greater velocities or reduced time durations to determine more factors such as strength response. Tempo studies should aim to complete the same TUT for protocols to determine measures for hypertrophic response.

Analysis of Compliance with Time under Tension and Force during Strengthening Exercises with Elastic Bands.

Quantifying training variables of a physical exercise modality is essential for an appropriate dosage. In training with elastic bands, time under tension (TUT) and force represent the duration and intensity of this force-training modality. The aims of this study were to evaluate the degree of compliance to TUT prescription for three different scenarios of two exercises and the comparison of the force values obtained versus the estimate values. A total of 29 healthy volunteers were evaluated in a clinical environment under controlled conditions in 3 different scenarios (different velocities or ROMs) of both shoulder abduction and knee extension in 2 sets of 10 repetitions per scenario within a single session. Concentric and isometric phases showed a higher degree of compliance for their TUTs than the eccentric phase TUTs for all scenarios of both exercises, whereas the degree of compliance was higher for the total TUT than for the phases’ TUTs. Additionally, the eccentric phase showed a general tendency to develop for longer time periods than prescribed, whilst the fast scenario showed a higher degree of compliance for isometric phase TUTs and total TUTs than the extant two scenarios in both exercises. On the other hand, the force of the elastic bands tends to be overestimated according to the estimates of the manufacturers. These findings, both those related to the degree of compliance with TUTs and the force analysis, can be used by physiotherapists and other exercise professionals as a reference to achieve a good dosage of routine exercises with elastic bands.

Effect of bench press at a specified movement tempo on post-exercise testosterone and cortisol levels

Body response is a key element of the periodization of any training unit. The main control systems in the human body are the nervous and endocrine systems. The study aims to examine the effect of bench press at a specified movement tempo on post-exercise blood testosterone and cortisol levels. The study involved 16 men (experience in resistance training 5.5 ± 1.3 years, aged 24 ± 2 years, body weight 86.1 ± 7.2 kg, and 1RM 125 ± 17 kg). The first stage of the test focused on determining the maximum force based on a single bench press with the highest possible external load (1RM). The second stage included the main test, i.e. bench press. The participants were asked to perform 5 sets successively, with an external load of 70% of an individual 1RM and as many repetitions as possible. The tempo of the exercise was precisely specified. The metronome was used to set a bench press tempo. The movement tempo included time under tension (TUT) 2/0/2/0. TUT means the total time of muscle tension during one repetition. The tests showed significant changes in cortisol levels recorded 30 minutes after exercise, amounting to 13.75 (±4.60) at F=9.16 and p=0.006. and 60 minutes after exercise, amounting to 11.37 (±4.17) at F=19.46 and p=0.0002. No significant statistical values were found for testosterone levels. This study brings additional evidence of the importance of hormonal responses in muscle strength training.

Seated row and biceps curl exercises present similar acute responses on muscle thickness, arm circumference, and peak force for elbow flexors after a resistance training session in recreationally-trained subjects.

The primary purpose of this study was to measure the acute effects on muscle thickness, arm circumference, and peak force between unilateral seated row and unilateral biceps curl exercises for elbow flexors after a RT session in recreationally-trained subjects. Fourteen resistance-trained men (25.3±2.5years, 76.5±6.4kg, 174.6±7cm) performed 6 sets of 10RM and 2-min rest for one of two exercises (unilateral seated row exercise, USR or unilateral biceps curl, UBC). Muscle thickness (MT), arm circumference (AC), and peak force (PF) were measured before 10-min (control), pre-RT session and post-RT (immediately after, 15-min and 30-min). All acute RT variables were measured during both exercises: maximal number of repetitions (MNR), total number of repetitions (TNR), time under tension (TUT), rating of perceived exertion (RPE). Two-way ANOVAs were used to test differences between exercises and moments with an alpha of 5%. For PF, there was a significant difference between pre- and post-0 for UBC and USR (P<0.001). For AC, there were significant differences between pretest × post-0-min for both exercises (P<0.001). For MT, there were significant differences between pretest × post 0-min (P<0.001), pretest × post 15-min (P<0.001) for both exercises and pretest × post 30-min only for UBC (P=0.006). Both exercises induced similar increases in AC and MT for elbow flexors and reduction in peak force.

The Acute Effects of External Compression With Blood Flow Restriction on Maximal Strength and Strength-Endurance Performance of the Upper Limbs.

The main goal of the present study was to evaluate the acute effects external compression with blood flow restriction (BFR) at 100 and 150% of full arterial occlusion pressure (AOP) on maximal strength and strength-endurance performance during the bench press (BP) exercise. The study included 12 strength-trained male subjects (age = 23.2 ± 2.66 years; body mass = 75.3 ± 6.33 kg; height = 179.1 ± 3.82 cm), experienced in resistance training (5.7 ± 2.93 years). During the experimental sessions in a randomized crossover design, the subjects performed a 1 repetition maximum (1RM) test and three sets of the BP using 60% 1RM to failure with three different conditions: without BFR (NO-BFR); BFR with a pressure of 100% AOP (BFR100); and BFR with a pressure of 150% AOP (BFR150). The differences between the NO-BFR, BFR100, and BFR150 conditions were examined using repeated measures ANOVA. The ANOVA indicated significant main effect for condition in 1RM, number of performed repetitions (REP), and time under tension (TUT) (p < 0.01). Post hoc analyses for the main effect indicated significant increases in 1RM (p < 0.01; 95.00 ± 15.37 vs 91.87 ± 15.99), REP (p < 0.01; 17.56 ± 3.36 vs 15.67 ± 5.24), and TUT (p < 0.01; 32.89 ± 6.40 vs 28.72 ± 6.18) for the BFR150 condition compared to NO-BFR. Furthermore, significant increases in REP (p = 0.03; 17.56 ± 3.36 vs 16.47 ± 4.01) and TUT (p = 0.03; 32.89 ± 6.40 vs 30.00 ± 6.45) were observed for the BFR150 condition compared to the BFR100. The results of the present study indicate that high external compression increases maximal strength evaluated by the 1RM test, as well as endurance performance during three sets of the BP exercise.

Can Post-Activation Performance Enhancement (PAPE) Improve Resistance Training Volume during the Bench Press Exercise?

Background: The aim of the present study was to evaluate the effects of post-activation performance enhancement (PAPE) on resistance training volume during the bench press exercise (BP). The study included 12 healthy strength-trained males (age 25.2 ± 2.1 years, body mass 92.1 ± 8.7 kg, BP one-repetition maximum (1RM) 28.8 ± 10.5 kg, training experience 6.3 ± 2.1 years). Methods: The experiment was performed following a randomized crossover design, where each participant performed two different exercise protocols with a conditioning activity (CA) consisting of the BP with three sets of three repetitions at 85% 1RM (PAPE), and a control without the CA (CONT). To assess the differences between PAPE and CONT, the participants performed three sets of the BP to volitional failure at 60% 1RM. The differences in the number of performed repetitions (REP), time under tension (TUT), peak power output (PP), mean of peak power output (PPMEAN), mean power output (MP), peak bar velocity (PV), mean of peak bar velocity (PVMEAN), and mean bar velocity (MV) between the CONT and PAPE conditions were examined using repeated measures ANOVA. Results: The post-hoc analysis for the main condition effect indicated significant increases in TUT (p < 0.01) for the BP following PAPE, compared to the CONT condition. Furthermore, there was a significant increase in TUT (p < 0.01) in the third set for PAPE compared to the CONT condition. No statistically significant main effect was revealed for REP, PP, PV, PPMEAN, PVMEAN, MP, and MV. Conclusion: The main finding of the study was that the PAPE protocol increased training volume based on TUT, without changes in the number of preformed REP.

Monitoring the training dose and acute fatigue response during elbow flexor resistance training using a custom-made resistance band.

BackgroundHome-based resistance training offers an alternative to traditional, hospital-based or rehabilitation center-based resistance training and has attracted much attention recently. However, without the supervision of a therapist or the assistance of an exercise monitoring system, one of the biggest challenges of home-based resistance training is that the therapist may not know if the patient has performed the exercise as prescribed. A lack of objective measurements limits the ability of researchers to evaluate the outcome of exercise interventions and choose suitable training doses.ObjectiveTo create an automated and objective method for segmenting resistance force data into contraction phase-specific segments and calculate the repetition number and time-under-tension (TUT) during elbow flexor resistance training. A pilot study was conducted to evaluate the performance of the segmentation algorithm and to show the capability of the system in monitoring the compliance of patients to a prescribed training program in a practical resistance training setting.MethodsSix subjects (three male and three female) volunteered to participate in a fatigue and recovery experiment (5 min intermittent submaximal contraction (ISC); 1 min rest; 2 min ISC). A custom-made resistance band was used to help subjects perform biceps curl resistance exercises and the resistance was recorded through a load cell. The maximum and minimum values of the force-derivative were obtained as distinguishing features and a segmentation algorithm was proposed to divide the biceps curl cycle into concentric, eccentric and isometric contraction, and rest phases. Two assessors, who were unfamiliar with the study, were recruited to manually pick the visually observed cut-off point between two contraction phases and the TUT was calculated and compared to evaluate performance of the segmentation algorithm.ResultsThe segmentation algorithm was programmatically implemented and the repetition number and contraction-phase specific TUT were calculated. During isometric, the average TUT (3.75 ± 0.62 s) was longer than the prescribed 3 s, indicating that most subjects did not perform the exercise as prescribed. There was a good TUT agreement and contraction segment agreement between the proposed algorithm and the assessors.ConclusionThe good agreement in TUT between the proposed algorithm and the assessors indicates that the proposed algorithm can correctly segment the contraction into contraction phase-specific parts, thereby providing clinicians and researchers with an automated and objective method for quantifying home-based elbow flexor resistance training. The instrument is easy to use and cheap, and the segmentation algorithm is programmatically implemented, indicating good application prospect of the method in a practical setting.

The effects of resistance training experience on movement characteristics in the bench press exercise.

The main aim of this study was to determine whether the level of experience in strength training has a significant effect on differences in the value of exercise volume determined on time under tension (TUT) and number of repetition (REP) for a specific movement tempo. The study examined 68 men divided into groups of beginners and advanced strength trained athletes. The participants performed 5 sets of bench press (BP) at 70% 1RM using either a REG, MED or SLOW metronome guided cadence. Each set was performed to failure and with 3 min of rest between sets. Significant differences in TUT were found between the groups of beginners and advanced athletes for the slow (SLO) 6/0/4/0 tempo in set 1 (p = 0.01) and set 2 (p = 0.04), and for the regular (REG) 2/0/2/0 tempo in set 5 (p = 0.01). Significant differences were documented for total TUT between the beginners and advanced athletes for the SLO 6/0/4/0 tempo (p = 0.04). The results of ANOVA revealed significant differences in the number of repetitions between groups for the SLO 6/0/4/0 tempo in set 4 (p = 0.04) and set 5 (p = 0.04), and for the REG 2/0/2/0 tempo in set 5 (p = 0.01). The main finding of this study is that strength training experience has a significant effect on training volume, both in terms of TUT and REP at a specific constant movement tempo. Significant differences do not occur for each value of the tempo used.

The Influence of Grip Width on Training Volume During the Bench Press with Different Movement Tempos.

The aim of the study was to determine the effect of the wide-grip bench press (WGBP) and the close-grip bench press (CGBP) on the number of performed repetitions (REPs) and time under tension (TUT) using a variable tempo of movement. Twenty (20) women experienced in resistance training were enrolled in the study (1RM-CGBP = 55.2 ± 9.5 kg; 1RM-WGBP = 52.7 ± 8.5 kg). Participants performed 5 sets of the BP with a maximal number of REPs at 70%1RM. Different tempos of movement, i.e., slow (6/0/X/0) and fast (2/0/X/0), and grip widths, i.e., the CGBP and the WGBP, were employed. The following variables were registered: maximal number of repetitions in every set (REPSet1-5), total number of repetitions performed in 5 sets (TREP), maximal time under tension in every set (TUTSet1-5) and total time under tension in 5 sets (TTUT). The two-way ANOVA revealed statistically significant differences between the WGBPFAST and the WGBPSLOW in TUTSet1-5 (p < 0.05) and TTUT (p < 0.01), as well as between the CGBPFAST and the CGBPSLOW in TUTSet1-5 (p < 0.01) and TTUT (p < 0.01). Significant differences between the WGBPFAST and the WGBPSLOW were also observed in REPSet1-5 (p < 0.01) and TREP (p < 0.01) as well as between the CGBPFAST and the CGBPSLOW in REPSet1-5 (p < 0.01) and TREP (p < 0.01). No significant differences between the WGBPSLOW and the CGBPSLOW nor the WGBPFAST and the CGBPFAST were found. The study demonstrates that the tempo of movement, regardless of the width grip, has a significant effect on the volume of effort in resistance training.

The acute effects of caffeine intake on time under tension and power generated during the bench press movement

BackgroundThe ability to generate high levels of power is one of the key factors determining success in many sport disciplines. Although there are studies confirming ergogenic effects of caffeine (CAF) on different physical and mental abilities, much controversy remains about its influence on power. The main goal of this study was to assess the effects of caffeine supplementation on time under tension (TUT) and the number of performed repetitions (REP). The second objective was to determine the effects of CAF supplementation on power (P) and movement velocity (V) during the bench press movement. Additionally the authors evaluated whether CAF has a significant effect on velocity of the bar in the eccentric (ECC) phase (VEMEAN) of the bench press movement.MethodsThe study included 20 men (20–31 yrs., 87.3 ± 7.7 kg) with at least 2 years of experience in resistance training. The study participants were divided randomly into two groups: the supplemented group ingested caffeine before exercise (GCAF), while the control group was given a placebo (GCON). The exercise protocol consisted of performing the bench press movement with a load equal to 70%1RM with maximal possible velocity (X/0/X/0). The experimental sets were performed to momentary muscular failure.ResultsThe repeated measures ANOVA between the GCAF and GCON groups revealed statistically significant differences in 2 variables. Post-hoc tests demonstrated statistically significant differences in TUT when comparing the group supplemented with caffeine (13.689 s GCAF) to the one ingesting a placebo (15.332 s GCON) at p = 0.002. Significant differences were also observed in mean velocity during the eccentric phase of movement (0.690 m/s in the GCAF to 0.609 in GCON with p = 0.002). There were no significant differences in generated power and velocity in the CON phase of the movement between the GCAF and GCON.ConclusionsThe main finding of the study is that CAF ingestion increases movement velocity of the bar in the eccentric phase of the movement, what results in shortening of the time under tension (TUT) needed for performing a specific number of repetitions, without decreasing power and velocity in the CON phase of the movement.

Comparison of the Effects of Velocity-Based Training Methods and Traditional 1RM-Percent-Based Training Prescription on Acute Kinetic and Kinematic Variables

To compare kinetic and kinematic data from 3 different velocity-based training sessions and a 1-repetition-maximum (1RM)-percent-based training (PBT) session using full-depth, free-weight back squats with maximal concentric effort. Fifteen strength-trained men performed 4 randomized resistance-training sessions 96 h apart: PBT session involved 5 sets of 5 repetitions using 80% 1RM; load-velocity profile (LVP) session contained 5 sets of 5 repetitions with a load that could be adjusted to achieve a target velocity established from an individualized LVP equation at 80% 1RM; fixed sets 20% velocity loss threshold (FSVL20) session consisted of 5 sets at 80% 1RM, but sets were terminated once the mean velocity (MV) dropped below 20% of the threshold velocity or when 5 repetitions were completed per set; and variable sets 20% velocity loss threshold session comprised 25 repetitions in total, but participants performed as many repetitions in a set as possible until the 20% velocity loss threshold was exceeded. When averaged across all repetitions, MV and peak velocity (PV) were significantly (P < .05) faster during the LVP (MV effect size [ES] = 1.05; PV ES = 1.12) and FSVL20 (MV ES = 0.81; PV ES = 0.98) sessions compared with PBT. Mean time under tension (TUT) and concentric TUT were significantly less during the LVP sessions compared with PBT. The FSVL20 sessions had significantly less repetitions, total TUT, and concentric TUT than PBT. No significant differences were found for all other measurements between any of the sessions. Velocity-based training permits faster velocities and avoids additional unnecessary mechanical stress but maintains similar measures of force and power output compared with strength-oriented PBT in a single training session.

Self-selected vs. Fixed Repetition Duration: Effects on Number of Repetitions and Muscle Activation in Resistance-Trained Men.

Nóbrega, SR, Barroso, R, Ugrinowitsch, C, da Costa, JLF, Alvarez, IF, Barcelos, C, and Libardi, CA. Self-selected vs. fixed repetition duration: effects on number of repetitions and muscle activation in resistance-trained men. J Strength Cond Res 32(9): 2419-2424, 2018-The aim of this study was to compare the effects of self-selected and fixed repetition duration (RD) on resistance exercise (RE) volume, muscle activation, and time under tension (TUT) per repetition and per session. Twelve resistance-trained men participated in the study. A randomized cross-over design was used and each participant performed 2 high-intensity RE protocols in a balanced order: (a) 3 sets of RE with self-selected RD (SELF); and (b) 3 sets of RE with fixed RD (2-second concentric and 2-second eccentric [FIX]). Muscle activation was assessed through surface electromyography (EMG) of the vastus lateralis and vastus medialis throughout RE sessions. Overall, RE volume was significantly greater for SELF (p = 0.01), whereas TUT per repetition was significantly greater for FIX (p = 0.0001). No significant differences between protocols were detected for TUT per session. Between-protocol comparisons revealed significantly greater EMG amplitude for SELF compared with FIX at S1 (p = 0.01), S2 (p = 0.03), and S3 (p = 0.03). Both SELF and FIX protocols produced significant increases in EMG amplitude from 25 to 100% (p < 0.001) of set completion. Between-protocol comparisons revealed significantly greater EMG amplitude for SELF compared with FIX at 75% (p = 0.03) and 100% (p = 0.01). In conclusion, self-selected RD resulted in greater volume and muscle activation compared with fixed RD in an RE session.