scholarly journals Impact of resistance training status on trunk muscle activation in a fatiguing set of heavy back squats

2020 ◽  
Author(s):  
David R. Clark ◽  
Michael I. Lambert ◽  
Chris Grigson ◽  
Angus M. Hunter
Keyword(s):  
Body Mass ◽  
Muscle Activation ◽  
Vastus Lateralis ◽  
Erector Spinae ◽  
Group Differences ◽  
Neural Activation ◽  
Training Status ◽  
Neuromuscular Activation ◽  
Volitional Fatigue ◽  
Muscle Groups

Abstract Purpose In this study we measured neural activation (EMG) in four trunk stabilizer muscles and vastus lateralis (VL) in trained and novice participants during a set of squat repetitions to volitional fatigue at 85% 1RM. Methods Forty males were recruited into two groups, novice (NG: n = 21) and experienced (EG: n = 19), according to relative squat 1RM. Participants were tested twice to: (1) determine squat 1RM, and (2) complete a single set of repetitions to volitional fatigue at 85% 1RM. Relative squat 1RM; NG < 140% body mass, EG > 160% body mass. Neuromuscular activation was measured by EMG for the following: rectus abdominus (RA), external oblique (EO), lumbar sacral erector spinae (LSES), upper lumbar erector spinae (ULES) and VL in eccentric and concentric phase. Completed repetitions, RPE and EMG in repetition 1 and at 20, 40, 60, 80 and 100% of completed repetitions were analysed. Results No group differences were found between number repetitions completed and RPE in repetitions to volitional fatigue at 85% 1RM. Neuromuscular activation increased significantly in all muscle groups in eccentric and concentric phase apart from RA in the eccentric phase. Trunk neuromuscular activation was higher in NG compared to EG and this was significant in EO, LSES and ULES in eccentric phase and LSES in the concentric phase. VL activation increased in both phases with no group differences. Conclusion Trunk neuromuscular activation increases in a fatiguing set of heavy squats regardless of training status. Increased back squat strength through training results in lower neuromuscular activation despite greater absolute external squat loads.

scholarly journals Comparison of Core Muscle Activation Between a Prone Bridge and 6-RM Back Squats

2018 ◽  
Vol 62 (1) ◽  
pp. 43-53 ◽  
Author(s):  
Roland van den Tillaar ◽  
Atle Hole Saeterbakken
Keyword(s):  
Body Mass ◽  
Muscle Activation ◽  
Body Height ◽  
Rectus Abdominis ◽  
Erector Spinae ◽  
Emg Activity ◽  
Exercise Time ◽  
Lower Back ◽  
Total Exercise Time ◽  
External Oblique

AbstractThe purpose of this study was to compare core muscle activation during a prone bridge (plank) until failure and 6-RM back squats. Twelve resistance-trained males (age 23.5 ± 2.6 years, body mass 87.8 ± 21.3 kg, body height 1.81 ± 0.08 m) participated in this study. Total exercise time and EMG activity of the rectus abdominis, external abdominal oblique and erector spinae were measured during 6-RM back squats and a prone bridge with a weight of 20% of participants’ body mass on their lower back. The main findings showed non-significant differences between the exercises in the rectus abdominis or external oblique, but greater erector spinae activation in squatting. Furthermore, in contrast to the prone bridge, the erector spinae and rectus abdominis demonstrated increasing muscle activation throughout the repetitions while squatting, whereas the prone bride demonstrated increasing external oblique activation between the beginning and the middle of the set. It was concluded that since squatting resulted in greater erector spine activation, but similar rectus abdominis and oblique external activation as the prone bridge, high-intensity squats rather than isometric low intensity core exercises for athletes would be recommended.

scholarly journals Isometric and dynamic strength and neuromuscular attributes as predictors of vertical jump performance in 11- to 13-year-old male athletes

2017 ◽  
Vol 42 (9) ◽  
pp. 924-930 ◽  
Author(s):  
Brandon John McKinlay ◽  
Phillip J. Wallace ◽  
Raffy Dotan ◽  
Devon Long ◽  
Craig Tokuno ◽  
...  
Keyword(s):  
Vastus Lateralis ◽  
Peak Torque ◽  
Soccer Players ◽  
Neural Activation ◽  
Male Athletes ◽  
Neuromuscular Activation ◽  
Jump Performance ◽  
Rate Of Torque Development ◽  
Dynamic Contractions ◽  
Torque Development

In explosive contractions, neural activation is a major factor in determining the rate of torque development, while the latter is an important determinant of jump performance. However, the contribution of neuromuscular activation and rate of torque development to jump performance in children and youth is unclear. The purpose of this study was to examine the relationships between the rate of neuromuscular activation, peak torque, rate of torque development, and jump performance in young male athletes. Forty-one 12.5 ± 0.5-year-old male soccer players completed explosive, unilateral isometric and dynamic (240°/s) knee extensions (Biodex System III), as well as countermovement-, squat-, and drop-jumps. Peak torque (pT), peak rate of torque development (pRTD), and rate of vastus lateralis activation (Q30) during the isometric and dynamic contractions were examined in relation to attained jump heights. Isometric pT and pRTD were strongly correlated (r = 0.71) but not related to jump performance. Dynamic pT and pRTD, normalized to body mass, were significantly related to jump height in all 3 jumps (r = 0.38–0.66, p < 0.05). Dynamic normalized, but not absolute pRTD, was significantly related to Q30 (r = 0.35, p < 0.05). In young soccer players, neuromuscular activation and rate of torque development in dynamic contractions are related to jump performance, while isometric contractions are not. These findings have implications in the choice of training and assessment methods for young athletes.

Strength training counteracts motor performance losses during bed rest

2003 ◽  
Vol 95 (4) ◽  
pp. 1485-1492 ◽  
Author(s):  
Minoru Shinohara ◽  
Yasuhide Yoshitake ◽  
Motoki Kouzaki ◽  
Hideoki Fukuoka ◽  
Tetsuo Fukunaga
Keyword(s):  
Strength Training ◽  
Muscle Activation ◽  
Vastus Lateralis ◽  
Knee Extensor ◽  
Bed Rest ◽  
Training Group ◽  
Medial Gastrocnemius ◽  
Knee Extensors ◽  
Extensor Muscles ◽  
Muscle Groups

The purpose of the study was to determine the effect of bed rest with or without strength training on torque fluctuations and activation strategy of the muscles. Twelve young men participated in a 20-day bed rest study. Subjects were divided into a non-training group (BRCon) and a strength-training group (BRTr). The training comprised dynamic calf-raise and leg-press exercises. Before and after bed rest, subjects performed maximal contractions and steady submaximal isometric contractions of the ankle extensor muscles and of the knee extensor muscles (2.5-10% of maximal torque). Maximal torque decreased for both the ankle extensors (9%, P < 0.05) and knee extensors (16%, P < 0.05) in BRCon but not in BRTr. For the ankle extensors, the coefficient of variation (CV) for torque increased in both groups ( P < 0.05), with a greater amount ( P < 0.05) in BRCon (88%) compared with BRTr (41%). For the knee extensors, an increase in the CV for torque was observed only in BRCon (22%). The increase in the CV for torque in BRCon accompanied the greater changes in electromyogram amplitude of medial gastrocnemius (122%) and vastus lateralis (59%) compared with BRTr ( P < 0.05). The results indicate that fluctuations in torque during submaximal contractions of the extensor muscles in the leg increase after bed rest and that strength training counteracted the decline in performance. The response varied across muscle groups. Alterations in muscle activation may lead to an increase in fluctuations in motor output after bed rest.

Design of novel running leggings with thermoplastic polyurethane membrane compression zones

2018 ◽  
Vol 89 (8) ◽  
pp. 1533-1545
Author(s):  
Gozde Goncu Berk ◽  
Sinem Kahveci
Keyword(s):  
Water Vapor ◽  
Repeated Measures ◽  
Muscle Activation ◽  
Vastus Lateralis ◽  
Thermoplastic Polyurethane ◽  
Water Vapor Permeability ◽  
Muscle Performance ◽  
Vapor Permeability ◽  
Compression Garments ◽  
Muscle Groups

Compression garments are widely used by athletes to improve athletic performance and to avoid potential injuries. Some compression garments are developed to exert pressure on muscle groups via thermoplastic polyurethane (TPU) membrane layers laminated on the textile surface. This study investigates the effect of novel TPU membrane patterns on muscle performance of the lower extremities and on the comfort parameters of air and water vapor permeability. Three novel running leggings with TPU membrane compression zones were designed to exert pressure on the major muscle groups used during running. Electromyography (EMG) measurements of the female participants wearing the designed leggings with TPU membranes, conventional leggings and shorts were recorded during a standardized squat protocol via a wireless surface EMG system. A repeated measures analysis of variance with a Greenhouse–Geisser correction determined that the mean root of mean square values for the EMG signals retrieved from the rectus femoris, vastus lateralis, gastrocnemius and hamstring muscles while wearing a specific legging design revealed statistically significant reductions in muscle activation. On the other hand, comfort tests exhibited low water vapor permeability and air permeability results when the textile surface was laminated with the TPU membrane. TPU membranes laminated on athletic wear to create compression zones could be effective in reducing muscle activation. Comfort performance is another essential design parameter that should be integrated into the design decisions. Large surfaces of solid TPU membranes should be minimized and surface textures should be employed for increased breathability.

Effect of Absolute and Relative Loading on Muscle Activity During Stable and Unstable Squatting

2010 ◽  
Vol 5 (2) ◽  
pp. 177-183 ◽  
Author(s):  
Jeffrey M. McBride ◽  
Tony R. Larkin ◽  
Andrea M. Dayne ◽  
Tracie L. Haines ◽  
Tyler J. Kirby
Keyword(s):  
Body Mass ◽  
Muscle Activity ◽  
Vastus Lateralis ◽  
Force Plate ◽  
Rest Period ◽  
Biceps Femoris ◽  
Erector Spinae ◽  
Repetition Maximum ◽  
Maximum Test ◽  
Significant Difference

Purpose:The purpose of this investigation was to determine the effect of stable and unstable conditions on one repetition maximum strength and muscle activity during dynamic squatting using absolute and relative loading.Methods:Ten recreationally weight-trained males participated in this study (age = 24.1 ± 2.0 y, height = 178.0 ± 5.6 cm, body mass = 83.7 ± 13.4 kg, 1RM/body mass = 1.53 ± 0.31), which involved two laboratory sessions separated by 1 wk. Linear position transducers were used to track bar displacement while subjects stood on a force plate for all trials. Vastus lateralis (VL), biceps femoris (BF) and erector spinae (L1) muscle activity (average integrated EMG [IEMG]) was also recorded during all trials. During the frst session subjects complete a one repetition maximum test in a stable dynamic squat (S1RM = 128.0 ± 31.4 kg) and an unstable dynamic squat (U1RM = 83.8 ± 17.3 kg) in a randomized order with a 30-min rest period between conditions. The second session consisted of the performance of three trials each for 12 different conditions (unstable and stable squats using three different absolute loads [six conditions] and unstable and stable squats using three different relative loads [six conditions]).Results:Results revealed a statistically significant difference between S1RM and U1RM values (P < .05). The stable trials resulted in the same or a significantly higher value for VL, BF and L1 muscle activity in comparison with the unstable trials for all twelve conditions.Conclusions:Unstable squatting is of equal or less (depending on the loading condition) benefit to improving or maximizing muscle activity during resistance exercise.

Recovery of Gait After Stroke: What Changes?

2008 ◽  
Vol 22 (6) ◽  
pp. 676-683 ◽  
Author(s):  
Jaap H. Buurke ◽  
Anand V. Nene ◽  
Gert Kwakkel ◽  
Victorien Erren-Wolters ◽  
Maarten J. IJzerman ◽  
...  
Keyword(s):  
Functional Recovery ◽  
Muscle Activation ◽  
Vastus Lateralis ◽  
Erector Spinae ◽  
Walking Ability ◽  
Muscle Coordination ◽  
Control Test ◽  
Trunk Control ◽  
Coordination Patterns ◽  
Over Time

Background. Little is known about whether changes in coordination patterns of muscle activation after stroke are related to functional recovery of walking. Objective . The present study investigated the longitudinal relationship between changes in neuromuscular activation patterns of paretic muscles in hemiplegic gait and improvement in walking ability after stroke. Methods. Thirteen patients diagnosed with a first unilateral ischemic stroke had their recovery of walking measured by the Rivermead Mobility Index, Functional Ambulation Categories, Barthel Index, Trunk Control Test, Motricity Index, and comfortable walking speed. Surface electromyography (SEMG) of the erector spinae, gluteus maximus, gluteus medius, rectus femoris, vastus lateralis, semitendinosus, gastrocnemius, and tibialis anterior muscles of both legs was used to quantify coordination patterns in comfortable walking mode. All clinical and electromyography-related measurements were taken at 3, 6, 9, 12, and 24 weeks poststroke. Timing parameters of the SEMG patterns were calculated, using an objective burst detection algorithm, and analyzed with the measures of functional recovery. Results . All functional measures, except Trunk Control Test, showed statistically significant improvement over time, whereas SEMG patterns did not change significantly over time. Conclusion. The lack of significant change in SEMG patterns over time suggests that functional gait improvements may be more related to compensatory strategies in muscle activation of the unaffected leg and biomechanical changes than by restitution of muscle coordination patterns in the affected leg.

scholarly journals Relationships between Height, Mass, Body Mass Index, and Trunk Muscle Activation during Seated Whole-Body Vibration Exposure

Vibration ◽  
2021 ◽  
Vol 4 (4) ◽  
pp. 822-835
Author(s):  
Megan E. Govers ◽  
Alexander J. Nolan ◽  
Marwan Hassan ◽  
Michele L. Oliver
Keyword(s):  
Body Mass Index ◽  
Low Back Pain ◽  
Back Pain ◽  
Body Mass ◽  
Muscle Activation ◽  
Whole Body Vibration ◽  
Erector Spinae ◽  
Whole Body ◽  
Back Injury ◽  
Low Back

Operators of heavy equipment are often exposed to high levels of whole-body vibration (WBV), which has been associated with a variety of adverse health outcomes. Although anthropometric factors are known to impact vibration dose and risk of low back pain, studies have yet to investigate the influence of anthropometric factors on muscle activation during WBV exposure. This study quantified the relationships between muscle activation, vibration frequency, body mass, body mass index (BMI), and height both pre- and post-fatigue. Muscle activation of the external oblique (EO), internal oblique (IO), lumbar erector spinae (LE) and thoracic erector spinae (TE) were quantified using surface electromyography. Results indicate increased activation with increased mass, BMI, and frequency for the LE, TE, and IO, which may be a result of increased activation to stabilize the spine. Decreased muscle activation with increased height was seen in the TE, IO, and pre-fatigue EO, which could indicate higher risk for low back injury since height is associated with increased forces on the spine. This may contribute to the association between increased low back pain incidence and increased height. Results suggest that ISO 2631-1 health guidance should incorporate anthropometric factors, as these may influence muscle activation and back injury risk.

scholarly journals Using a Back Exoskeleton During Industrial and Functional Tasks—Effects on Muscle Activity, Posture, Performance, Usability, and Wearer Discomfort in a Laboratory Trial

2021 ◽  
pp. 001872082110072
Author(s):  
Tessy Luger ◽  
Mona Bär ◽  
Robert Seibt ◽  
Monika A. Rieger ◽  
Benjamin Steinhilber
Keyword(s):  
Heart Rate ◽  
Muscle Activity ◽  
Vastus Lateralis ◽  
Erector Spinae ◽  
Stair Climbing ◽  
Trunk Flexion ◽  
User Friendliness ◽  
Timed Up And Go ◽  
System Usability Scale ◽  
Task Accomplishment

Objective To investigate the effect of using a passive back-support exoskeleton (Laevo V2.56) on muscle activity, posture, heart rate, performance, usability, and wearer comfort during a course of three industrial tasks (COU; exoskeleton worn, turned-on), stair climbing test (SCT; exoskeleton worn, turned-off), timed-up-and-go test (TUG; exoskeleton worn, turned-off) compared to no exoskeleton. Background Back-support exoskeletons have the potential to reduce work-related physical demands. Methods Thirty-six men participated. Activity of erector spinae (ES), biceps femoris (BF), rectus abdominis (RA), vastus lateralis (VL), gastrocnemius medialis (GM), trapezius descendens (TD) was recorded by electromyography; posture by trunk, hip, knee flexion angles; heart rate by electrocardiography; performance by time-to-task accomplishment (s) and perceived task difficulty (100-mm visual analogue scale; VAS); usability by the System Usability Scale (SUS) and all items belonging to domains skepticism and user-friendliness of the Technology Usage Inventory; wearer comfort by the 100-mm VAS. Results During parts of COU, using the exoskeleton decreased ES and BF activity and trunk flexion, and increased RA, GM, and TD activity, knee and hip flexion. Wearing the exoskeleton increased time-to-task accomplishment of SCT, TUG, and COU and perceived difficulty of SCT and TUG. Average SUS was 75.4, skepticism 11.5/28.0, user-friendliness 18.0/21.0, wearer comfort 31.1 mm. Conclusion Using the exoskeleton modified muscle activity and posture depending on the task applied, slightly impaired performance, and was evaluated mildly uncomfortable. Application These outcomes require investigating the effects of this passive back-supporting exoskeleton in longitudinal studies with longer operating times, providing better insights for guiding their application in real work settings.

scholarly journals Association between body mass index and subcortical brain volumes in bipolar disorders–ENIGMA study in 2735 individuals

2021 ◽  
Author(s):  
Sean R. McWhinney ◽  
◽  
Christoph Abé ◽  
Martin Alda ◽  
Francesco Benedetti ◽  
...  
Keyword(s):  
Body Mass Index ◽  
Body Mass ◽  
Bipolar Disorders ◽  
Ventricular Volume ◽  
Group Differences ◽  
Intracranial Volume ◽  
Brain Volumes ◽  
Lateral Ventricles ◽  
Mixed Effects Modeling ◽  
Subcortical Volumes

AbstractIndividuals with bipolar disorders (BD) frequently suffer from obesity, which is often associated with neurostructural alterations. Yet, the effects of obesity on brain structure in BD are under-researched. We obtained MRI-derived brain subcortical volumes and body mass index (BMI) from 1134 BD and 1601 control individuals from 17 independent research sites within the ENIGMA-BD Working Group. We jointly modeled the effects of BD and BMI on subcortical volumes using mixed-effects modeling and tested for mediation of group differences by obesity using nonparametric bootstrapping. All models controlled for age, sex, hemisphere, total intracranial volume, and data collection site. Relative to controls, individuals with BD had significantly higher BMI, larger lateral ventricular volume, and smaller volumes of amygdala, hippocampus, pallidum, caudate, and thalamus. BMI was positively associated with ventricular and amygdala and negatively with pallidal volumes. When analyzed jointly, both BD and BMI remained associated with volumes of lateral ventricles  and amygdala. Adjusting for BMI decreased the BD vs control differences in ventricular volume. Specifically, 18.41% of the association between BD and ventricular volume was mediated by BMI (Z = 2.73, p = 0.006). BMI was associated with similar regional brain volumes as BD, including lateral ventricles, amygdala, and pallidum. Higher BMI may in part account for larger ventricles, one of the most replicated findings in BD. Comorbidity with obesity could explain why neurostructural alterations are more pronounced in some individuals with BD. Future prospective brain imaging studies should investigate whether obesity could be a modifiable risk factor for neuroprogression.

scholarly journals The Influence of Maturation on the Oxygen Uptake Efficiency Slope

2012 ◽  
Vol 24 (3) ◽  
pp. 347-356 ◽  
Author(s):  
Michael P. Rogowski ◽  
Justin P. Guilkey ◽  
Brooke R. Stephens ◽  
Andrew S. Cole ◽  
Anthony D. Mahon
Keyword(s):  
Oxygen Uptake ◽  
Body Mass ◽  
Cycle Ergometer ◽  
Group Differences ◽  
Healthy Male ◽  
Uptake Efficiency ◽  
Graded Exercise ◽  
Oxygen Uptake Efficiency Slope ◽  
Male Subjects ◽  
One Way Anova

This study examined the influence of maturation on the oxygen uptake efficiency slope (OUES) in healthy male subjects. Seventy-six healthy male subjects (8–27 yr) were divided into groups based on maturation status: prepubertal (PP), midpubertal (MP), late-pubertal (LP), and young-adult (YA) males. Puberty status was determined by physical examination. Subjects performed a graded exercise test on a cycle ergometer to determine OUES. Group differences were assessed using a one-way ANOVA. OUES values (VO2L·min1/log10VEL·min−1) were lower in PP and MP compared with LP and YA (p < .05). When OUES was expressed relative to body mass (VO2mL·kg−1·min−1/log10VEmL·kg−1·min−1) differences between groups reversed whereby PP and MP had higher mass relative OUES values compared with LP and YA (p < .05). Adjusting OUES by measures of body mass failed to eliminate differences across maturational groups. This suggests that qualitative factors, perhaps related to oxidative metabolism, account for the responses observed in this study.

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