Publications
Publications
Publications
Students working in the Dankel Lab have the opportunity to submit their research to be published.
Students have been published in the Journal of Sport Rehabilitation, Clinical Physiology and Functional Imaging, the Journal of Ultrasound, Psychology of Sport and Exercise, International Journal of Sport and Exercise Psychology, and the Journal of Sports Medicine and Physical Fitness.
Access our student publications below. View Dr. Dankel's publications here.
Student Publications
A systematic review and meta-analysis quantifying the increase in energy expenditure from electrical stimulations
Luke P Gordy, Joseph M Juliano, Thomas B Goerke, Scott M Hubbard, Adam A Shehata, Scott J Dankel
Objective: The prevalence of obesity in the United States is around 40%, yet less than 10% of these individuals meet established exercise guidelines. Neuromuscular electrical stimulations may serve as a more palatable alternative to vonluntary exercise. The purpose of this systematic review and meta-analysis was to quantify the increase in energy expenditure resulting from neuromusuclar electrical stimulations administered to healthy adults and clinical populations, and to assess its effectiveness as an alternate to traditional exercise. Design:Systematic review and meta-analysis. Methods: The research databases of Medline, Scopus, and Web of Science were searched on June 3, 2025 with the following inclusion criteria: 1) written in English, 2) electrical stimulations administered to skeletal muscles without any other exercise, 3) provide an estimate of energy expenditure or oxygen uptake, 4) administered to humans, and 5) also have a resting energy expenditure estimate. A three-level random effects meta-analytic model was computed. The effect sizes used in the present study were raw energy expenditure values in Kcals. Results: A total of 36 studies met the inclusion criteria which included 72 effect sizes and 491 participants. The mean weighted increase in energy expenditure was 36.04 (95% CI: 21.23, 50.85; p<0.001) Kcals/30 minutes. Conclusion: Neuromuscular electrical stimulations increase energy expenditure, but the magnitude appears to be much smaller (~40%) than that of walking. Individuals who are overweight may use electrical stimulations as an alternative to voluntary exercise if they are unwilling or incapable of exercising, but it is unlikely to be as effective as voluntary exercise.
A 2-Week Peer-Leader Program to Increase Participation and Benefits Associated with Resistance Training
Luke P Gordy, Jack M Chernyenko, Juliet C Schott, Shannon O Leusner, Viacheslav Tymoshenko, Zachary N Fuery, Kevin B George, Melanie Alverio, Scott J Dankel
Many individuals do not engage in resistance exercise, in part, because they lack the knowledge and confidence to do so. A total of 42 individuals (26 females, 16 males) were recruited to complete four sessions with a peer-leader coach. They were then encouraged to continue attending the campus recreation weight room over the following 10 weeks. Individuals reported an increase in both knowledge (p < .001) and confidence (p < .001) using the weight room, and this corresponded to attending the recreation center an average of 1.4 times per week. General well-being did not change (p = .921), but there were increases in muscle mass of both the upper (p = .03) and lower body (p = .031). There were small increases in isokinetic strength of the upper (p = .006), but not lower body (p = .173).
A systematic review and meta-analysis examining if hyperplasia occurs in humans in response to resistance exercise
Nicholas V Barton, Hitesh N Gowda, Scott J Dankel
Introduction: While it is understood that resistance exercise in humans induces muscle growth primarily via muscle hypertrophy, there is some debate as to whether muscle hyperplasia also occurs. The purpose of this meta-analysis was to quantitively assess whether the presence of muscle hyperplasia occurs in humans performing resistance training.
Evidence acquisition: Medline, Scopus, and Web of Science were searched on May 17, 2024. Studies that measured or reported sufficient data to estimate muscle fiber number before and after resistance training were included in a three-level random effects model. Fiber number was estimated from the ratio of muscle cross-sectional area to fiber cross-sectional area.
Evidence synthesis: A total of 11 studies met the inclusion criteria. Changes in fiber number were estimated in the biceps brachii or vastus lateralis muscles. Meta-analysis results indicated that resistance exercise did not significantly alter the estimated number of muscle fibers (ES: 4086; 95% CI: -6430, 14,604; P=0.419). Additionally, the presence of muscle hyperplasia was not moderated by prior training status, training duration, or the muscle group analyzed (all P>0.05).
Conclusions: These findings suggest that meaningful changes in muscle fiber number are unlikely to occur in humans following resistance training interventions lasting up to 6 months. While muscle hyperplasia was not evident, it may be difficult to detect due to the relatively short duration of the included training interventions and/or difficulties in estimating muscle fiber number, which resulted in a wide range of estimates across studies.
Affective responses to identical resistance exercises that are prescribed and self-selected
Allowing individuals to self-select their aerobic exercises has been shown to increase enjoyment, but less is known on how self-selecting resistance exercise impacts enjoyment. Individuals came to the laboratory for three sessions of knee extensions each separated by seven days. During the first session, individuals were instructed to self-select the exercise load, number of repetitions, and the rest period between sets. The second session was designed to determine how many repetitions individuals could perform at their self-selected load, and to vary the exercise loads to reduce the likelihood that individuals could recall what they self-selected on visit 1. The third session involved completing the same exercise that was performed on session 1, except the individuals were prescribed the exercise. At the conclusion of each set, individuals were asked to rate their exercise induced feelings, felt-arousal, discomfort, and repetitions in reserve. A total of 27 individuals (17 males, 10 females) completed the study. On average, individuals exercised 2.8 (5.9) repetitions short of volitional task failure, which corresponded to performing 88.3 (28.5) % of the repetitions that could have been completed with the self-selected load. The self-selected exercise session resulted in greater affective responses (2.6 vs. 1.9; BF10 = 10.516), felt-arousal (3.6 vs. 3.1; BF10 = 89.157), and discomfort (3.7 vs. 2.8; BF10 = 20.350) as compared to the prescribed exercise session. Allowing individuals to self-select their resistance exercise protocols increased enjoyment, which may help to increase long-term adherence.
Perceptions and physiologic responses between electrical stimulations and voluntary resistance exercise
Hitesh N. Gowda, Nicholas V. Barton, Jason M. Morphew, Samuel M. Skripko,
Kevin A. Rice & Scott J. Dankel
Kevin A. Rice & Scott J. Dankel
Neuromuscular electrical stimulations (E-STIM) may provide a potential alternative to that of voluntary resistance exercise, but less is known on how individuals perceive E-STIM which may determine long-term adherence and was the purpose of the present study. Forty-seven individuals (18 females) completed this study involving 3 sets of 10 isometric leg extensions. One leg completed these exercises at the voluntary maximum, while the other underwent E-STIM administered at the maximal tolerable intensity. Measurements of fatigue (change in isometric strength), muscle swelling (change in muscle thickness) discomfort, perceptual ratings of fatigue, exercise-induced feelings, and preferred exercise mode were recorded. Bayes Factors (BF10) were used as support for the null (BF10 < 0.33) or alterative (BF10 > 3) hypotheses. The torque output generated during the E-STIM protocol was about 10% of what could be generated voluntarily (BF10 = 8.416e20). Muscle swelling appeared to occur to a larger extent in response to the voluntary exercise protocol when compared to E-STIM (voluntary: 0.10 cm vs. E-STIM: 0.01 cm; BF10 = 2.224), but neither protocol induced fatigue (voluntary: −5.9Nm vs. E-STIM: 4.4Nm; both BF10 < 0.5). There were no differences in discomfort (voluntary: 5.5 vs. E-STIM: 5.6; BF10 = 0.227) or exercise-induced feelings (Voluntary: 0.3 vs. E-STIM: 0.7; BF10 = 0.634), but individuals tended to prefer performing E-STIM (55.3%) over that of voluntary (29.8%) exercise (BF10 = 24.611). While most individuals prefer E-STIM over that of voluntary resistance exercise, the amplitudes selected by individuals may not be sufficient to induce favourable adaptations.
Affective, perceptual and physiologic responses to isokinetic contractions under blood flow restriction
Jordyn N Heckler, Scott J Dankel
Background: Blood flow restriction (BFR) has been shown to enhance the effectiveness of low load resistance exercise, but less research has examined its utility in conjunction with maximal isokinetic contractions, which may depend on the restrictive pressure and speed of contraction.
Methods: Individuals reported to the laboratory for three visits to complete three sets of 20 maximal elbow flexion exercises at 60°/s and 300°/s under 0%, 40% and 80% of their arterial occlusion pressure. Muscle thickness was measured before and after exercise, and ratings of discomfort, perceived activation, and exercise-induced feelings were obtained at the completion of each exercise. Fatigue was assessed as the decline in average peak torque across the three sets.
Results: A total of 27 individuals (11 females, 16 males) completed the study. There was a significant interaction for torque at both 60°/s and 300°/s (P<0.001), with each increasing pressure resulting in greater fatigue. Muscle swelling was present across all conditions but was lowest in the 40% BFR condition applied during the 300°/s speed. At both 60°/s and 300°/s speeds, the 80% BFR pressure was associated with lower enjoyment, greater discomfort, and greater perceived activation (all P<0.05).
Conclusions: The combined effects of BFR to maximal isokinetic contractions increased fatigue with less of an impact on muscle swelling. These results indicate that BFR may enhance the effectiveness of long-term isokinetic training, but it is also important to consider the addition of BFR was associated with lower levels of enjoyment and greater discomfort which may decrease adherence.
The combined effectiveness of therapeutic ultrasound, electrical stimulations, and blood flow restriction to treat symptoms of muscle damage
Nicole E Fallon, Catherine E Faust, Scott J Dankel
This study assessed whether symptoms of muscle damage could be reduced by a combination of therapeutic ultrasound and electrical stimulations, and whether this could be enhanced by blood flow restriction. Before and 48 h after performing eccentric elbow flexion exercises, individuals completed assessments of muscle damage. A 10-min therapeutic ultrasound and electrical stimulation treatment
was then applied with and without blood flow restriction to assess short (5 min) and long-term (24 h) improvements. Twenty-three individuals completed the study (11 females). Data were analysed using Bayesian repeated measures ANOVAs. The damaging exercise increased discomfort (BF10 = 2.93e14) and relaxed joint angle (BF10 = 2425.90) while decreasing pain pressure threshold (BF10 = 289.71). Each of these variables was acutely improved with the combination treatment protocol (all BF10 ≥ 74) with no added effect of blood flow restriction. A combination of therapeutic ultrasound and interferential electrical stimulations appeared effective at acutely alleviating symptoms of muscle damage with no additive effect of blood flow restriction.
A systematic review examining if blood flow restriction can enhance the effectiveness of electrical stimulations
Abstract
Introduction: The use of blood flow restriction (BFR) has been shown to promote greater increases in muscle size and strength when applied during low intensity aerobic exercise and low load resistance exercise. Whether BFR can enhance the effectiveness of E-STIM has been less explored and is the purpose of this study.
Evidence acquisition: The databases of Pubmed, Scopus, and Web of Science were searched using the following search: "blood flow restriction" OR "occlusion training" OR "KAATSU" AND "electrical stimulation" OR "E-STIM" OR "neuromuscular electrical stimulation" OR "NMES" OR "electromyostimulation." A three-level random effects restricted maximum likelihood model was computed.
Evidence synthesis: Four studies met the inclusion criteria. There was no additive effect of performing E-STIM under BFR when compared to E-STIM in the absence of BFR [ES: 0.88 (95% CI: -0.28, 2.05); P=0.13]. There was a greater increase in strength when E-STIM was performed under BFR as compared to the same protocol without BFR [ES: 0.88 (95% CI: 0.21, 1.54); P=0.01].
Conclusions: The lack of effectiveness for BFR to enhance muscle growth may be related to the non-orderly recruitment of motor units when performing E-STIM. The ability of BFR to augment increases in strength may also allow individuals to utilize lower amplitudes to reduce participant discomfort.
Blood flow restricted electrical stimulations to prevent or attenuate symptoms of muscle damage
Hannah E Cintron, Jessica J Heyburn, Robert L Sterner, Scott J Dankel
The objective of this study was to determine if performing electrical stimulations (E-STIM) under blood flow restriction (BFR) would result in a greater protective effect against symptoms of muscle damage. 18 individuals (9 females) completed a damaging bout of exercise followed by a low frequency E-STIM treatment protocol on both arms, one of which was completed under BFR. The treatment protocol was then repeated 24-hours post-exercise. There were main effects of time for muscle thickness (pre: 3.5 cm; 48 h post: 3.8 cm; BF10 = 88.476), discomfort (pre: 0.0 au; 48 h post: 4.2 au; BF10 = 241.996), and isometric strength (pre: 278 N; 48 h post: 232 N; BF10 = 10,289.894) which all changed as a result of the damaging exercise protocol, but there were no differences between conditions [all Bayes Factors (BF10) < 0.28]. The effectiveness of low frequency E-STIM for preventing the onset of exercise-induced muscle damage would not appear to be enhanced if performed under BFR.
The impact of blood flow restricted electrical stimulations on recovery from muscle damage
LaNiece J Brown, Alexa N Gasser, Robert L Sterner, Scott J Dankel
Background
Both electrical stimulations (E-STIM) and blood flow restriction (BFR) have been shown to treat symptoms of exercise-induced muscle damage, but little is known about their combined effects which was the purpose of this study.
Methods
Individuals completed one set of eccentric elbow flexion exercises to induce muscle damage. Forty-eight hours later, E-STIM was applied using an interferential current administered to both arms for 20 min; however, only one arm completed the E-STIM protocol while also undergoing repeated bouts of BFR (full occlusion for 2 min separated by a 1-min rest intervals). Discomfort and isometric strength were assessed immediately before the damaging exercise, immediately before the treatments, and 0, 10, and 30 min posttreatment.
Results
A total of 22 individuals (11 females) completed the study. There were no interactions with respect to discomfort (BF10 = 0.008) or isometric strength (BF10 = 0.009) indicating that the addition of BFR did not alter the effectiveness of E-STIM. There was a main effect of time indicating that the damaging exercise was successful at depressing torque (pre: 284 N, post: 199 N; BF10 = 2.70e9) and inducing discomfort (pre: 0 au, post: 6.4 au; BF10 = 3.21e17). While isometric strength did not recover with the E-STIM treatments, discomfort was reduced at each the immediate post (5.3 au; BF10 = 56 294) 10-min post (5.0 au; BF10 = 46 163), and 30-min post (4.9 au; BF10 = 707 600) time points.
Conclusion
E-STIM may be useful for treating discomfort, but does not appear capable of recovering strength associated with muscle damage. The efficacy of E-STIM would not appear to be enhanced if performed under BFR.
A systematic review examining blood flow restriction in combination with isokinetic resistance exercise
John J Welsh, Drew M Robinson, Scott J Dankel
Objectives: Many studies have examined the efficacy of blood flow restriction (BFR) applied during isotonic muscle actions, but its application with isokinetic exercise has been less explored and was the purpose of this systematic review.
Design: Systematic Review.
Methods: The online databases of Pubmed, Scopus, and Web of Science were searched on May 16, 2023 using the following search: “blood flow restriction OR kaatsu OR occlusion AND isokinetic.” To be included in this review, the manuscripts had to incorporate human participants, involve the use of BFR during isokinetic exercise, and be written in English. Given limited studies comparing the same exercise completed with and without BFR, a quantitative meta-analysis was not completed.
Results: Twenty-one studies met the inclusion criteria, most of which incorporated concentric isokinetic contractions at 30% of peak torque using 40-60% of arterial occlusion pressure. Acutely, the addition of BFR did not appear to increase heart rate, blood pressure, muscle swelling, blood flow, or delayed onset muscle soreness, but it did increase markers of muscle activation. Chronically, the addition of BFR did not appear to enhance muscle hypertrophy, but augmentations in muscle strength depended on the speed and type of contraction.
Conclusion: The use of BFR during isokinetic exercise does not appear as effective when compared to isotonic exercise. Future studies may wish to examine different intensities and speeds of isokinetic exercises to determine its potential efficacy.
Machines and free weight exercises: a systematic review and meta-analysis comparing changes in muscle size, strength, and power
Abstract
Introduction: To compare changes in muscle size, strength, and power between free-weight and machine-based exercises.
Evidence acquisition: The online databases of Pubmed, Scopus, and Web of Science were each searched using the following terms: ""free weights" OR barbells OR dumbbells AND machines" up until September 15, 2020. A three-level random effects meta-analytic model was used to compute effect sizes.
Evidence synthesis: When strength was tested using a free-weight exercise, individuals training with free-weights gained more strength than those training with machines [ES: 0.655; (95% CI: 0.269, 1.041)]. When strength was tested a machine-based exercise incorporated as part of the machine-based training program, individuals training with machines gained more strength than those training with free-weights [ES: -0.784 (95% CI: -1.223, -0.344)]. When strength was tested using a neutral device, machines and free-weight exercises resulted in similar strength gains [ES: 0.128 (95% CI: -0303, 0.559)]. There were no differences in the change in power [ES: -0.049 (95% CI: -0.557, 0.460)] or muscle hypertrophy [ES: -0.01 (95% CI: -0.525, 0.545)] between exercise modes.
Conclusions: Individuals looking to increase strength and power should take into account the specificity of exercise, and how their strength and power will be tested and applied. Individuals looking to increase general strength and muscle mass to maintain health may choose whichever activity they prefer and are more likely to adhere to.
The impact of cuff width on perceptual responses during and following blood flow restricted walking exercise
Nicole E. Fallon, Emely Urbina, Dominic V. Whitener, Mana H. Patel, Ryan J. Exner
Abstract
Methods: Individuals completed two identical walking trials, once with 12-cm wide cuffs and once with 17-cm wide cuffs. Five 2-min walking bouts were completed at a speed of 50 m/min, with a 1-min rest period between sets. The restriction cuffs were inflated to 40% of the individuals’ arterial occlusion pressure taken with each respective cuff. Individuals were asked to rate their discomfort, perceived exertion (RPE), and cuff preference.
Results: Twenty-seven individuals completed the study. The 12-cm cuff required a higher occlusion pressure which resulted in a higher absolute pressure applied (58 vs. 52 mm Hg; BF10 = 19 331.897). Whilst there was no difference in RPE values between cuffs (BF10 = 0.474), individuals reported greater discomfort when using the wider cuffs (2.3 vs. 1.7; BF10 = 252.786). The majority of individuals (63%) preferred to use the narrower cuff, whereas fewer preferred the wider cuff (26%) and even fewer did not have a preference (11%).
Discussion: Blood flow restricted walking exercise performed with narrower restriction cuffs appeared to reduce participant discomfort whilst also being preferred over that of wider cuffs. Future studies may wish to test the influence of different restrictive cuff widths on alterations in gait patterns during blood flow restricted walking exercise.
The impact of acute and chronic resistance exercise on muscle stiffness: a systematic review and meta-analysis
Abstract
Purpose: Ultrasound is commonly used to measure changes in skeletal muscle morphology in response to both acute and chronic resistance exercise, but little is known on how muscle stiffness changes via ultrasound elastography, which was the purpose of this systematic review and meta-analysis.
Methods: The online data bases of Pubmed, Scopus, and Web of Science were each searched up until February 2020 and the data were analyzed using a random effects model.
Results: A total of eight studies (four acute and four chronic) met the inclusion criteria for the quantitative analysis. Following a single bout of exercise, muscle stiffness was increased within the first hour [ES: 1.52 (95% CI 0.14, 2.91); p = 0.031], but was no longer elevated when measured 2 days post-exercise [ES: 0.76 (95% CI - 0.32, 1.83); p = 0.16] or ≥ 7 days post-exercise [ES: 0.20 (95% CI - 0.53, 0.94); p = 0.58]. There was no impact of long-term resistance training on changes in muscle stiffness [ES: - 0.04 (95% CI - 0.24, 0.15); p = 0.653].
Conclusion: The primary findings from this meta-analysis indicate that muscle stiffness increases acutely following a single bout of resistance exercise, but does not change long-term with chronic resistance training when measured via ultrasound shear elastography. Given the small number of studies included in this review, future studies may wish to examine changes in muscle stiffness in response to both acute and chronic resistance exercise.
The impact of postexercise blood flow restriction on local muscle endurance of a remote limb
Paul J. Sandbach, Marlon S. Carvajalo
Abstract
Background: Studies have examined the influence of postexercise blood flow restriction as a mechanism to activate muscle afferents and assess nonlocal muscle fatigue. Although these studies have assessed fatigue during maximal contractions, less is known about how these afferents may impact submaximal local muscle endurance, which was the purpose of the present study.
Methods: Individuals completed two testing visits which involved completing a set of elbow flexion exercises to volitional failure on the nondominant followed by the dominant arm. During both trials, a pneumatic cuff was placed at the top of the nondominant arm before exercise. This cuff was inflated to either 0% (control) or 70% (experimental) of the individual's arterial occlusion pressure immediately after the set was completed. We then evaluated how this impacted local muscle endurance of the dominant arm using a Bayesian paired samples t-test with an uninformed prior width of 0.707 centred on 0.
Results: A total of 36 individuals completed the study (18 females). There was a greater discomfort present in the experimental trial when compared to the control trial (control: 4.5 standard deviation [SD]: 2.4); experimental: 5.8 [SD: 1.9]; BF10 = 61.46), but there were no differences in repetitions completed on the dominant arm (control: 43 [SD: 9], experimental: 43 [SD: 10]; BF10 = 0.179).
Conclusions: Applying blood flow restriction postexercise induced sensations of discomfort but did not alter the local muscle endurance of the contralateral limb. These results suggest that increasing the activation of muscle afferents does not appear to alter the submaximal muscle endurance of a remote limb.
Assessing the effectiveness of Compare Assistant for improving intra-rater reliability of ultrasound-measured muscle thickness
Tyler D Baer, Kevin A Rice, Emely Urbina, Dominic V Whitener, Scott J Dankel
Purpose
Muscle thickness measured via ultrasound is commonly used to assess muscle size. The purpose of this study was to determine if the reliability of this measurement will improve if using the Compare Assistant tool, and whether this depends on technician experience and the muscle being assessed.
Methods
Individuals came to the laboratory for two visits each separated by 24 h. On day 1, two ultrasound images were taken on the individual’s anterior upper arm (elbow flexors) and anterior lower leg (tibialis anterior) by two inexperienced and one experienced ultrasound technician. On day 2, three images were taken: (1) without looking at the previous images taken on day 1; (2) after re-examining the images taken on day 1, and (3) side-by-side with the images taken on day 1 via Compare Assistant. Bayes Factors (BF10) were used to provide evidence for the null (< 0.33) or alternative (> 3) hypotheses.
Results
There was no rater by measurement technique interaction (upper body: BF10 = 0.04, lower body: BF10 = 0.138), nor was there a main effect of measurement technique (upper body: BF10 = 0.052, lower body: BF10 = 0.331), indicating that reliability measures were not improved for either the upper body (CV%, no look: 2.92 vs. Compare Assistant: 2.87) or lower body (CV%, no look: 1.81 vs. Compare Assistant: 1.34) as a result of using Compare Assistant.
Conclusion
The results of this study suggest that day-to-day reliability of muscle thickness measurement may be limited by random biological variability as opposed to technician error.
Does performing resistance exercise to failure homogenize the training stimulus by accounting for differences in local muscular endurance?
Ryan J. Exner, Mana H. Patel, Dominic V. Whitener
Abstract
The prescription of resistance exercise often involves administering a set number of repetitions to be completed at a given relative load. While this accounts for individual differences in strength, it neglects to account for differences in local muscle endurance and may result in varied responses across individuals. One way of potentially creating a more homogenous stimulus across individuals involves performing resistance exercise to volitional failure, but this has not been tested and was the purpose of the present study. Individuals completed 2 testing sessions to compare repetitions, ratings of perceived exertion (RPE), muscle swelling and fatigue responses to arbitrary repetition (SET) vs. failure (FAIL) protocols using either 60% or 30% one-repetition maximum. Statistical analyses assessed differences in the variability between protocols. Forty-six individuals (25 females and 21 males) completed the study. There was more variability in the number of repetitions completed during FAIL when compared to SET protocols. Performing the 60% 1RM condition to failure appeared to reduce the variability in muscle swelling (average variance: 60%-SET = .034, 60%-FAIL = .023) and RPE (average variance: 60%-SET = 4.0, 60%-FAIL = 2.5), but did not alter the variability in muscle fatigue. No differences in variability were present between the SET-30% and FAIL-30% protocols for any of the dependent variables. Performing resistance exercise to failure may result in a more homogenous stimulus across individuals, particularly when using moderate to high exercise loads. The prescription of resistance exercise should account for individual differences in local muscle endurance to ensure a similarly effective stimulus across individuals.
Highlights
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There is a large variance in the number of repetitions individuals can complete even when exercising with the same relative load.
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Ratings of perceived exertion and muscle swelling responses become more homogenous when exercising to volitional failure as compared to using performing a set number of repetitions, particularly when moderate to higher loads are used.
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The prescription of exercise should take into consideration the individual's local muscle endurance as opposed to choosing an arbitrary number of repetitions to be completed at a given relative load.
The effect of increasing blood flow restriction pressure when the contractions are already occlusive
Vito V. Nucci, David H. Jarrett, Catherine M. Palmo, Brenna M. Razzano
Abstract
Introduction: To compare changes in muscle size, strength, and power between free-weight and machine-based exercises.
Evidence acquisition: The online databases of Pubmed, Scopus, and Web of Science were each searched using the following terms: ""free weights" OR barbells OR dumbbells AND machines" up until September 15, 2020. A three-level random effects meta-analytic model was used to compute effect sizes.
Evidence synthesis: When strength was tested using a free-weight exercise, individuals training with free-weights gained more strength than those training with machines [ES: 0.655; (95% CI: 0.269, 1.041)]. When strength was tested a machine-based exercise incorporated as part of the machine-based training program, individuals training with machines gained more strength than those training with free-weights [ES: -0.784 (95% CI: -1.223, -0.344)]. When strength was tested using a neutral device, machines and free-weight exercises resulted in similar strength gains [ES: 0.128 (95% CI: -0303, 0.559)]. There were no differences in the change in power [ES: -0.049 (95% CI: -0.557, 0.460)] or muscle hypertrophy [ES: -0.01 (95% CI: -0.525, 0.545)] between exercise modes.
Conclusions: Individuals looking to increase strength and power should take into account the specificity of exercise, and how their strength and power will be tested and applied. Individuals looking to increase general strength and muscle mass to maintain health may choose whichever activity they prefer and are more likely to adhere to.