Electromyographic comparison of the barbell deadlift using constant versus variable resistance in healthy, trained men.
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ABSTRACT:
SUBMITTER: Andersen V
PROVIDER: S-EPMC6342300 | biostudies-literature | 2019
REPOSITORIES: biostudies-literature
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Project description:The main purpose of this review was to systematically analyze the literature concerning studies which have investigated muscle activation when performing the Deadlift exercise and its variants. This study was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Statement (PRISMA). Original studies from inception until March 2019 were sourced from four electronic databases including PubMed, OVID, Scopus and Web of Science. Inclusion criteria were as follows: (a) a cross-sectional or longitudinal study design; (b) evaluation of neuromuscular activation during Deadlift exercise or variants; (c) inclusion of healthy and trained participants, with no injury issues at least for six months before measurements; and (d) analyzed "sEMG amplitude", "muscle activation" or "muscular activity" with surface electromyography (sEMG) devices. Major findings indicate that the biceps femoris is the most studied muscle, followed by gluteus maximus, vastus lateralis and erector spinae. Erector spinae and quadriceps muscles reported greater activation than gluteus maximus and biceps femoris muscles during Deadlift exercise and its variants. However, the Romanian Deadlift is associated with lower activation for erector spinae than for biceps femoris and semitendinosus. Deadlift also showed greater activation of the quadriceps muscles than the gluteus maximus and hamstring muscles. In general, semitendinosus muscle activation predominates over that of biceps femoris within hamstring muscles complex. In conclusion 1) Biceps femoris is the most evaluated muscle, followed by gluteus maximus, vastus lateralis and erector spinae during Deadlift exercises; 2) Erector spinae and quadriceps muscles are more activated than gluteus maximus and biceps femoris muscles within Deadlift exercises; 3) Within the hamstring muscles complex, semitendinosus elicits slightly greater muscle activation than biceps femoris during Deadlift exercises; and 4) A unified criterion upon methodology is necessary in order to report reliable outcomes when using surface electromyography recordings.
| S-EPMC7046193 | biostudies-literature
Project description:The purpose of this investigation was to compare changes in circulating lymphocyte subset cell counts between high-intensity interval exercise (HIIE), sprint interval exercise (SIE), and moderate-intensity continuous exercise (MICE). Recreationally active men (n = 11; age: 23 ± 4 yr; height: 179.9 ± 4.5 cm; body mass: 79.8 ± 8.7 kg; body fat %:12.6 ± 3.8%; V̇O2max: 46.6 ± 3.9 ml⋅kg-1⋅min-1) completed a maximal graded exercise test to determine maximal oxygen uptake (V̇O2max) and three duration-matched cycling trials (HIIE, SIE, and MICE) in a randomized, counterbalanced fashion. HIIE consisted of fifteen 90-s bouts at 85% V̇O2max interspersed with 90-s active recovery periods. SIE consisted of fifteen 20-s bouts at 130% maximal power and 160-s active recovery periods. MICE was a continuous bout at 65% V̇O2max. Total exercise duration was 53 min in all three trials, including warm-up and cool-down. Blood was collected before, immediately post, 30 min, 2 h, 6 h, and 24 h post-exercise. Changes in lymphocyte subset counts, and surface expression of various markers were analyzed via flow cytometry. Changes were assessed using mixed model regression analysis with an autoregressive first order repeated measures correction. Significant decreases were observed in absolute counts of CD56dim NK cells, CD19+ B cells, CD4+ T cells, and CD8+ T cells 30 min and 24-h post-exercise in all three trials. Despite resulting in greater total work and oxygen consumption, MICE elicited similar changes in lymphocyte subset counts and receptor expression compared to both SIE and HIIE. Similarly, while the two interval trials resulted in differing oxygen consumption and total work, no differences in the lymphocyte response were observed. Though both forms of exercise resulted in declines in circulating lymphocyte cell counts, neither exercise type provides an immune-related advantage when matched for duration.
| S-EPMC8790298 | biostudies-literature
Project description:The aims of this study were to compare power output during a bench press throw (BPT) executed with (BPTbounce) and without (BPT) the barbell bounce technique, and examine the effect of cueing different barbell descent velocities on BPT power output in resistance-trained males. In total, 27 males (age 23.1 ± 2.1 years; body mass 79.4 ± 7.4 kg; height 178.8 ± 5.5 cm; and 4.6 ± 1.9 years of resistance training experience) were recruited and attended one familiarization session and two experimental sessions (EXP 1 and EXP 2). The force–velocity profile during maximal BPT and BPTbounce (randomized order) under different loads (30–60 kg) was established (EXP 1), and the effect of varying external barbell descent velocity cues “slow, medium, and as fast as possible” (i.e., “fast”) on the power output for each technique (BPT and BPTbounce) was examined (EXP 2). Comparing two BPT techniques (EXP 1), BPTbounce demonstrated 7.9–14.1% greater average power (p ≤ 0.001, ES = 0.48–0.90), 6.5–12.1% greater average velocity (p ≤ 0.001, ES = 0.48–0.91), and 11.9–31.3% shorter time to peak power (p ≤ 0.001–0.05, ES = 0.33–0.83) across the loads 30–60 kg than BPT. The cueing condition “fast” (EXP 2) resulted in greater power outcomes for both BPT and BPTbounce than “slow.” No statistically significant differences in any of the power outcomes were observed between “medium” and “slow” cuing conditions for BPT (p = 0.097–1.000), whereas BPTbounce demonstrated increased average power and velocity under the “medium” cuing condition, compared to “slow” (p = 0.006–0.007, ES = 0.25–0.28). No statistically significant differences were observed in barbell throw height comparing BPT and BPTbounce under each cuing condition (p = 0.225–1.000). Overall, results indicate that both bouncing the barbell and emphasizing barbell descent velocity be considered to improve upper body power in athlete and non-athlete resistance-training programs.
| S-EPMC9208083 | biostudies-literature
Project description:Introduction: Variable power output (VP) is one of the main characteristics of a road cycling mass-start. Tolerating VP during outdoor road cycling highly influences performance. There is a lack of continuous and comprehensive measurements during this power condition. Accordingly, the aim of the present study was to investigate physiological response to VP vs. constant power output (CP) as well as the perceived exertion of these two power conditions, and to investigate if variations in power output which span above lactate threshold (LT), differ from variations below LT. Methods: 15 elite competitive cyclists completed three test days, including 1 day of baseline testing and 2 days of main testing, consisting of four bouts of 28 min at two different intensities, "low" at 70% of LT and "high" at 95% of LT, with VP and CP. VP was performed with a 15% fluctuation of the average power output every second minute. Maximal oxygen uptake (VO2), respiratory exchange ratio (RER), heart rate (HR), blood lactate (LA), rating of perceived exertion (RPE), cadence (RPM) and power output (W) were measured. Results: At both low and high intensity, the VP condition induced a significantly higher VO2, HR and LA than the CP condition. Whole-bout RPE was similar between power conditions at high intensity. Additionally, at the high intensity, cycling with VP led to a greater increase in LA and lesser increase in RPE compared to cycling with CP. Discussion: The results of this study show that, despite considerable differences in the demand during the VP and CP bouts, there are minor differences in the perceptual and physiological response directly following these two power conditions in a cohort of elite competitive cyclists. A practical implication of these findings is that training with VP seems to be a viable alternative to training with CP, at least at high intensity.
| S-EPMC7481374 | biostudies-literature
Project description:Joint kinetic characteristics during the eccentric phase are important in resistance exercises because eccentric actions with elastic potential energy storage lead to the energy recoil with large joint moment and power generation during the subsequent concentric phase. Previous studies assessed the force production capacity in the barbell hip thrust; however, these were reported by the methodology using only surface electromyographic amplitudes recorded in the lower back and thigh muscles and did not focus on eccentric action. This study aimed to determine kinetic characteristics of lumbosacral, hip and knee joints of sprinters during the eccentric and concentric phases in a barbell hip thrust, compared to those of deadlift and back squat. Eleven well-trained male sprinters participated in this study. Each participant performed two full ranges of motion repetition using their previously determined six-repetition maximum loads. During strength exercises, reflective marker displacements attached to the body and a barbell were captured using 22 high-speed cameras, and ground reaction forces were captured using 4 force plates simultaneously. In the barbell hip thrust, as well as deadlift, the peak values of the lumbosacral and hip extension moments were generated almost immediately after the eccentric phase and were 24% and 42% larger than those in the back squat, respectively. In the knee joint, the largest was the peak extension moment in the back squat (155 ± 28 Nm), followed in order by that in the barbell hip thrust (66 ± 33 Nm) and that in the deadlift (24 ± 27 Nm). These demonstrated that a barbell hip thrust, as well as deadlift, can be a resistance exercise to strengthen the lower back and posterior thigh muscles. Thus, these resistance exercises may be able to be used separately according to their intended purposes, enabling transformations of strength training to specific dynamic motions such as sprint running.
| S-EPMC8248606 | biostudies-literature
Project description:BackgroundConventional intravenous patient-controlled analgesia (PCA), which usually involves constant-rate background infusion plus demand dosing, may cause adverse effects or insufficient analgesia. When variable-rate feedback infusion plus demand dosing mode is used, the infusion rate can be changed according to the patient's needs.MethodsIn this prospective randomized double-blind study, 78 adults who were undergoing spinal fusion surgery were randomly allocated to either the constant-rate background infusion plus demand dosing group (group C) or the variable-rate feedback infusion plus demand dosing group (group V). The number of demands, volume delivered, numerical rating scale (NRS) score, adverse effects and the use of rescue analgesics were examined at 30 minutes after the operation in the post-anesthesia care unit, and at 6, 12, 24, and 48 hours.ResultsThe number of demands was significantly lower in group V than in group C at 12-24 hours (4.59 ± 4.31 vs 9.21 ± 6.79 times, P = .001) and over the total period. The volume delivered via PCA was significantly lower in group V than in group C at 12 to 24 hours (13.96 ± 13.45 vs 21.19 ± 8.66 mL, P = .006), 24 to 48 hours (13.39 ± 12.44 vs 33.6 ± 12.49 mL, P = .000), and over the total period. NRS scores, administration of rescue analgesics, and postoperative nausea and vomiting showed no between-group differences.ConclusionsVariable-rate feedback infusion plus the demand dosing mode can control postoperative pain more efficiently, with lower dosages of analgesics, than constant-rate background infusion plus demand dosing in patients who undergo spinal fusion surgery.
| S-EPMC6417619 | biostudies-literature
Project description:Greater muscular strength is generally associated with superior sports performance, for example, in jumping, sprinting, and throwing. This meta-analysis aims to compare the effects of variable-resistance training (VRT) and constant-resistance training (CRT) on the maximum strength of trained and untrained subjects. PubMed, Web of Science, and Google Scholar were comprehensively searched to identify relevant studies published up to January 2022. Fourteen studies that met the inclusion criteria were used for the systematic review and meta-analysis. Data regarding training status, training modality, and type of outcome measure were extracted for the analyses. The Cochrane Collaboration tool was used to assess the risk of bias. The pooled outcome showed improved maximum strength with VRT, which was significantly higher than that with CRT (ES = 0.80; 95% CI: 0.42-1.19) for all the subjects. In addition, trained subjects experienced greater maximum-strength improvements with VRT than with CRT (ES = 0.57; 95% CI: 0.22-0.93). Based on subgroup analyses, maximum-strength improvement with a VRT load of ≥80% of 1 repetition maximum (1RM) was significantly higher than that with CRT (ES = 0.76; 95% CI: 0.37-1.16) in trained subjects, while no significant differences were found between VRT and CRT for maximum-strength improvement when the load was <80% (ES = 0.00; 95% CI: -0.55-0.55). The untrained subjects also achieved greater maximum strength with VRT than with CRT (ES = 1.34; 95% CI: 0.28-2.40). Interestingly, the improved maximum strength of untrained subjects with a VRT load of <80% of 1RM was significantly higher than that with CRT (ES = 2.38; 95% CI: 1.39-3.36); however, no significant differences were noted between VRT and CRT when the load was ≥80% of 1RM (ES = -0.04; 95% CI: -0.89-0.81). Our findings show that subjects with resistance training experience could use a load of ≥80% of 1RM and subjects without resistance training experience could use a load of <80% of 1RM to obtain greater VRT benefits.
| S-EPMC9317775 | biostudies-literature
Project description:Various definitions of fitness are essentially based on the number of descendants of an allele or a phenotype after a sufficiently long time. However, these different definitions do not explicate the continuous evolution of life histories. Herein, we focus on the eigenfunction of an age-structured population model as fitness. The function generates an equation, called the Hamilton-Jacobi-Bellman equation, that achieves adaptive control of life history in terms of both the presence and absence of the density effect. Further, we introduce a perturbation method that applies the solution of this equation to the long-term logarithmic growth rate of a stochastic structured population model. We adopt this method to realize the adaptive control of heterogeneity for an optimal foraging problem in a variable environment as the analyzable example. The result indicates that the eigenfunction is involved in adaptive strategies under all the environments listed herein. Thus, we aim to systematize adaptive life histories in the presence of density effects and variable environments using the proposed objective function as a universal fitness candidate.
| S-EPMC8437290 | biostudies-literature
Project description:BackgroundDeep-brain stimulation targeting the subthalamic nucleus (STN) can be used to treat motor symptoms and dyskinesia in the advanced stages of Parkinson's disease (PD). High-frequency stimulation (HFS) of the STN can lead to consistent, long-term improvement of PD symptoms. However, the effects of HFS on the axial symptoms of PD, specifically freezing of gait, can be limited or cause further impairment. While this can be alleviated via relatively low-frequency stimulation (LFS) in selected patients, LFS does not control all motor symptoms of PD. Recently, the National Engineering Laboratory for Neuromodulation reported preliminary findings regarding an efficient way to combine the advantages of HFS and LFS to form variable-frequency stimulation (VFS). However, this novel therapeutic strategy has not been formally tested in a randomized trial.Methods/designWe propose a multicenter, double-blind clinical trial involving 11 study hospitals and an established deep-brain stimulation team. The participants will be divided into a VFS and a constant-frequency stimulation group. The primary outcome will be changes in stand-walk-sit task scores after 3 months of treatment in the "medication off" condition. Secondary outcome measures include specific item scores on the Freezing of Gait Questionnaire and quality of life. The aim of this trial is to investigate the efficacy and safety of VFS compared with constant-frequency stimulation.DiscussionThis is the first randomized controlled trial to comprehensively evaluate the effectiveness and safety of VFS of the STN in patients with advanced PD. VFS may represent a new option for clinical treatment of PD in the future.Trial registrationClinicalTrials.gov, NCT03053726. Registered on February 15, 2017.
| S-EPMC6924017 | biostudies-literature
Project description:Microtubule-dependent transport is most often driven by collections of kinesins and dyneins that function in either a concerted fashion or antagonistically. Several lines of evidence suggest that cargo transport may not be influenced appreciably by the combined action of multiple kinesins. Yet, as in previous optical trapping experiments, the forces imposed on cargos will vary spatially and temporally in cells depending on a number of local environmental factors, and the influence of these conditions has been largely overlooked. Here, we characterize the dynamics of structurally defined complexes containing multiple kinesins under the controlled loads of an optical force clamp. While demonstrating that there are generic kinetic barriers that restrict the ability of multiple kinesins to cooperate productively, the spatial and temporal properties of applied loads is found to play an important role in the collective dynamics of multiple motor systems. We propose this dependence has implications for intracellular transport processes, especially for bidirectional transport.
| S-EPMC3270990 | biostudies-literature