Article

Electromyographic and Kinetic Comparison of the Back Squat and Overhead Squat

March 2014
The Journal of Strength and Conditioning Research 28(10):2827-2836

DOI:10.1519/JSC.0000000000000462

Source
PubMed

Authors:

Rodrigo Raul Aspe

Robert Gordon University

Paul Swinton

Robert Gordon University

The purpose of this study was to compare muscle activity and kinetics during the back squat and overhead squat performed at three relative intensities (60, 75 and 90% 3RM). Fourteen subjects (age: 26 ± 7 yrs, height: 182.5 ± 13.5 cm, body mass: 90.5 ± 17.5 kg) performed each exercise using a within-subjects crossover design. In addition, a selection of trunk isolation exercises were included to provide additional comparisons. Squats were performed on a force platform with electromyographic (EMG) activity of the anterior deltoid (AD), rectus abdominis (RA), external oblique (EO), erector spinae (ES), gluteus maximus (GM), vastus lateralis (VL), biceps femoris (BF), and lateral gastrocnemius (GA) recorded throughout. The overhead squat demonstrated significantly greater (p<0.05) activity in the anterior trunk muscles (RA and EO) during the eccentric phase. However, the magnitudes of the differences were relatively small (∼ 2 to 7%). In contrast, the back squat displayed significantly greater (p<0.05) activity in the posterior aspect of the trunk (ES) and all lower-body muscles during the concentric phase. Kinetic comparisons revealed that significantly greater peak force (p<0.05) was developed during the back squat. EMG comparisons between the trunk isolation exercises and squat variations demonstrated substantially greater anterior trunk activity during the isolation exercises, whereas the highest activity in the posterior aspect of the trunk was obtained during the squats (p<0.05). The results of the study do not support the hypothesis that the overhead squat provides a substantially greater stimulus for developing the trunk musculature compared with the back squat.

Comparison of Muscle Activation During Toes to Bar Movement Performed with Different Techniques

Article

Full-text available

Jun 2023

With the increasing importance of physical fitness in the world, physical activity types such as CrossFit, which includes high-intensity combined movements, have become popular. The aim of this study was to compare the rectus abdominis (RA) muscle activation during the kipping toes-to-bar (KTB) and the strict toes-to-bar (STB) movements. RA muscle activation was measured during the KTB and STB exercises in 12 healthy young men. Participants performed 5 repetitions of both KTB and STB exercises in randomized order. Participants performed both exercises with a 5-minute rest interval. For comparing the RA muscle activity during the KTB and STB paired sample t-test was used. A significant difference was found between the KTB (359.56 ± 160.50 μV) and the STB (415.37 ± 185.63 μV) for RA muscle activation (p<0.05). These findings demonstrated that the difference in RA muscle activity during the STB and KTB movements showcases the importance of the STB movement on the RA that revealed greater motor units’ activation in a non-oscillation position. The study finding emerges that the same exercise can lead to different motor unit activations in the same muscle group, depending on the way the movement is performed.

Muscle Activation during the Squat Performed in Different Ranges of Motion by Women

Article

Full-text available

Jan 2023

Purpose: To analyze the muscle activation of the rectus femoris (RF), vastus lateralis (VL), gluteus maximus (GM), and biceps femoris (BF) in concentric and eccentric actions in the squat at 90 • and 140 • range of motion. Methods: Thirty-five women (32.9 ± 7.4 years; 64.5 ± 11.5 kg; 1.63 ± 0.1 m; BMI: 24.2 ± 2.9 kg/m 2 ; %fat: 24.9 ± 6.5%) experienced exercise for at least eight weeks. Electrodes were positioned in standardized locations. The signals were acquired by an A/D SAS1000 V8 converter and the electromyographic activity normalized in the percentage of the highest produced value (%RMS). The data were analyzed using repeated measures two-way ANOVA, with effect size (η 2) and differences calculated in percentage points (∆ p.p.). Results: The RF (p = 0.001; ∆ = 5.1 p.p.) and BF activation (p = 0.020; ∆ = 4.0 p.p.) was higher at 90 • in the eccentric action. The RF showed an interaction between the range of motion and %RMS, with a large effect size (F = 37.9; p = 0.001; η 2 = 0.485). The VL activation was higher at 140 • (p = 0.005; ∆ = 3.9 p.p.) in the concentric action and higher at 90 • (p = 0.006; ∆ = 3.7 p.p.) in the eccentric action, with a large effect size significant interaction (F = 21.3; p = 0.001; η 2 = 0.485). The GM activation was higher at 90 • in the concentric (p = 0.020; ∆ = 5.4 p.p.) and eccentric action (p = 0.022; ∆ = 41 p.p.). Conclusions: The biarticular muscles were influenced by the squat range only in the eccentric action of the movement, while the monoarticular muscles were influenced by the squat in both concentric and eccentric muscle action.

A systematic review on the muscular activation on the lower limbs with five different variations of the squat exercise

Article

Full-text available

Sep 2020

The squat is one of the most commonly used resistance exercises for performance and health due to its biomechanical and neuromuscular similarities to a wide range of athletic and everyday activities. There is a large number of squat variations (based on the descent depth, width of the stance, bar placement) with significant biomechanical and neuromuscular differences between them. The aim of this study was to systematically review the scientific literature to gather data on the muscular activation of the lower limb during different variants of the squat exercise. High-bar squat (full range of motion, to parallel and partial range of motion), low-bar squat, front squat, overhead squat and guided squat on Smith machine were included in the analysis. 30 articles met the inclusion criteria and were reviewed. Quality of the included studies was analysed with the PEDro scale. Main findings were that in the squat exercise activation of the knee-extensors is predominant. However, different activation patterns were observed with different distances between the feet, different depths, hips rotation or flexion, intensities. For instance, low-bar squat involves a greater hip hinge and thus, provokes major activation on the hip-extensors than other squat variations. It is worth highlighting that similar activation patterns were observed between the front squat and the high-bar squat. The variation with least activation was the guided squat. The evidence presented in this study may help the strength and conditioning professionals and practitioners with the exercise selection depending on the muscular targets and the individual characteristics of the athlete. Keywords: Electromyographic activity; Resistance exercise; Quadriceps; Gluteus; Hamstrings; Calves.

Trunk muscle activity during different types of low weighted squat exercises in normal and forefoot standing conditions

Article

Aug 2020
J SPORT SCI

Squats are considered a useful basic exercise for trunk muscle activation. To gain knowledge about trunk muscle activity patterns depending on the barbell position in beginners, we examined squats with low weights in the back, front, and overhead position. Methods: Twelve healthy adults (6 women/6 men, age: 29.1 (SD 8.0) y, height: 173.4 (6.9) cm, body mass: 70.1 (9.1) kg) randomly performed the three barbell squats in normal and in forefoot standing. Surface electromyography from external (EO) and internal oblique, rectus abdominis, and erector spinae (ES) was recorded. The centre of pressure path length (CoP) and the motion of the lumbar spine were captured. Results: The overhead squat revealed the highest percent muscle activity, where EO (p = 0.009) and ES (p = 0.03) showed the greatest activity. Forefoot standing did not change overall trunk muscle activities (.05< Hedges' g <.29, 0.17 < p < 0.95) although longer CoP path length (.45 < g < 1.3, p < 0.05) was measured. Conclusions: Squat exercises with low weight are useful to activate trunk muscles. Activity increases with the difficulty of the squat by frontal or overhead loading, but not by standing on the forefoot. The low weighted squat can target well core muscle activity in training with beginners or in rehabilitation.

A Comparison of Muscle Activation Among the Front Squat, Overhead Squat, Back Extension and Plank

Article

Full-text available

Apr 2020

International Journal of Exercise Science 13(1): 714-722, 2020. The purpose of this study was to compare the muscle activation of the scapula, leg, and trunk among the front squat (FS), overhead squat (OHS), back extension (BE) and plank (PL). Seven recreationally trained men (age: 28 ± 3.6 years, body mass: 92 ± 26.1 kg, height: 175 ± 5.3 cm, 3-RM front squat test: 125 ± 49.8 kg, 3-RM overhead squat test: 91 ± 15.5 kg) participated in this within-subject crossover design. Two isometric exercises (plank and Biering-Sorenson back extension) were also included for trunk musculature comparisons. Neuromuscular activitation of the vastus lateralis (VL), biceps femoris (BF), thoracic region of erector spinae (ES), middle trapezius (MT), rectus abdominis (RA), external oblique (EO), serratus anterior (SA), and anterior deltoid (AD). The neuromuscular activity of the FS and OHS were analyzed using a 2 X 3 (squat variation X intensity) repeated measures analysis of variance (ANOVA). Effects were further analyzed by Bonferroni corrected paired t-tests. Results showed that AD activity was significantly greater (p < .05) during the FS compared to OHS at 65 and 95% of the 3-RM, while MT activity was significantly greater (p < .05) during the OHS than the FS at 80 and 95% of the 3-RM. ES activity was significantly greater (p< .05) during both the FS and OHS compared to the BE, but PL elicited significantly greater EO and RA activity than both the FS and OHS. These findings reveal that the FS and OHS can help facilitate the activation of muscles supporting the shoulder complex, scapula and lower back.

Core Muscle Activation in Three Lower Extremity With Different Stability Requirements

Article

Feb 2022

Saeterbakken, AH, Stien, N, Pedersen, H, and Andersen, V. Core muscle activation in three lower extremity with different stability requirements. J Strength Cond Res XX(X): 000-000, 2019-The aim of the study was to compare core muscle surface electromyography (sEMG) during 3-repetition maximum (3RM) and the sEMG amplitude in the turnover from the descending to ascending phase in leg press, free-weight squats, and squats using the Smith machine. Nineteen women with 4.5 (±2.0) years of resistance training were recruited. After one familiarization session, the subjects performed 3RM in randomized order measuring electromyographic activity in the rectus abdominis, external oblique, and erector spinae. The exercises with the lowest stability requirements (leg press) demonstrated 17-59% and 17-42% lower core muscle sEMG amplitude than free weights and the Smith machine, respectively. No statistically significant differences were observed between the Smith machine and free weights. No statistically significant differences in turnover sEMG amplitude in the rectus abdominis between the exercises was observed, but lower sEMG amplitude was observed in external oblique and erector spinae in leg press compared with the other exercises. The 3RM loads in leg press were 54 and 47% greater than squats using the Smith machine and free weights, with 5% greater loads with the Smith machine than with free weights. In conclusion, lower mean and turnover core muscle sEMG amplitude were observed with the leg press but greater 3RM loads compared with squats with the Smith machine and free weights. The authors recommend that resistance-trained individuals use squats to include the core muscles in the kinetic chain, but there is no evidence that greater stability requirements (free weights instead of the Smith machine) will result in greater core muscle sEMG amplitude.

Muscle Activity Pattern with A Shifted Center of Pressure during the Squat Exercise

Article

Jun 2019
J SPORT SCI MED

The squat exercise is a fundamental movement in athletic training and rehabilitation. In this study, we measured muscle activities in a normal squat posture (NSP) and a squat posture with the center of foot pressure (COP) intentionally shifted forward as far as possible (FSP). Ten healthy men performed double-limb squats, adopting the NSP and FSP, with three knee flexion angles (30, 60, and 90 degrees). The muscle activities of the vastus medialis (VM), semitendinosus (ST), tibialis anterior (TA), and gastrocnemius muscle lateral head (GL) were measured using surface electromyography, and activity patterns were analyzed. Compared to that for the NSP, the COP was significantly shifted forward in the FSP by at least 30% of the foot length for all knee flexion angles (p < 0.05). At all knee flexion angles, VM muscle activity significantly decreased, while GL muscle activity increased, in the FSP compared to that for the NSP (p < 0.05). In addition, ST muscle activity increased significantly in the FSP compared to that for the NSP at knee flexion angles of 30 and 60 degrees (p < 0.05). TA muscle activity significantly decreased in the FSP compared to that for the NSP at only 90 degrees of knee flexion (p < 0.05). These results demonstrate that muscle activity patterns vary significantly according to squat posture. Thus, the active control of the COP position during the squat can be a new training approach in targeting specific muscle groups.

Contemporary perspectives of core stability training for dynamic athletic performance: a survey of athletes, coaches, sports science and sports medicine practitioners

Article

Jul 2018

Background: Core stability training has grown in popularity over 25 years, initially for back pain prevention or therapy. Subsequently, it developed as a mode of exercise training for health, fitness and sport. The scientific basis for traditional core stability exercise has recently been questioned and challenged, especially in relation to dynamic athletic performance. Reviews have called for clarity on what constitutes anatomy and function of the core, especially in healthy and uninjured people. Clinical research suggests that traditional core stability training is inappropriate for development of fitness for heath and sports performance. However, commonly used methods of measuring core stability in research do not reflect functional nature of core stability in uninjured, healthy and athletic populations. Recent reviews have proposed a more dynamic, whole body approach to training core stabilization, and research has begun to measure and report efficacy of these modes training. The purpose of this study was to assess extent to which these developments have informed people currently working and participating in sport. Methods: An online survey questionnaire was developed around common themes on core stability training as defined in the current scientific literature and circulated to a sample population of people working and participating in sport. Survey results were assessed against key elements of the current scientific debate. Results: Perceptions on anatomy and function of the core were gathered from a representative cohort of athletes, coaches, sports science and sports medicine practitioners (n = 241), along with their views on effectiveness of various current and traditional exercise training modes. Most popular method of testing and measuring core function was subjective assessment through observation (43%), while a quarter (22%) believed there was no effective method of measurement. Perceptions of people in sport reflect the scientific debate, and practitioners have adopted a more functional approach to core stability training. There was strong support for loaded, compound exercises performed upright, compared to moderate support for traditional core stability exercises. Half of the participants (50%) in the survey, however, still support a traditional isolation core stability training. Conclusion: Perceptions in applied practice on core stability training for dynamic athletic performance are aligned to a large extent to the scientific literature. Keywords:

Core and Lower limb Activations of the two-handed and Single-Handed Kettlebell Exercises

Article

Full-text available

Jan 2018

Two-dimensional video analysis of the overhead squat: a preliminary study

Article

Full-text available

Jul 2023

The aim of this study was to identify changes in the pattern of movement during performance of the overhead squat, as well as possible differences between the sexes, during a protocol of an extreme conditioning program. The subjects were eleven men (28.6 ± 4.5 years, 85.1 ± 8.4 kg, 1.80 ± 0.07 m, and 13.8 ± 7.7 months of practice) and eleven women (30.5 ± 4.8 years, 68.2 ± 10.36 kg, 1.70 ± 0.05 m, and 20.3 ± 17.01 months of practice), all of whom were extreme conditioning program practitioners. The protocol chosen for the training was the “Nautical Nancy”, which consisted of 5 rounds of 15 overhead squats and 400 meters of rowing. During the exercise, an analysis was performed in which the shoulder, knee, and hip flexion angles were analyzed in the first and last rounds. For men, there were increases of the shoulder and hip flexion angles, while the women showed increase of the shoulder flexion angle and decrease of the knee flexion angle. Changes in technique occurred due to the attempt at self-preservation on the part of the practitioners, when exposed to the protocol, which could lead to increased risk of injury. Key words: CrossFit; High Intensity Functional Training; Resistance Training; Biomechanics; Exercise Technique.

New Training Tasks for Stepwise Loading in Isometric Bodyweight Squat with Active Posture Control

Article

Full-text available

Sep 2021

Isometric bodyweight squats are fundamental exercises in athletic training and rehabilitation. Previously, we measured muscle activity in a normal squat posture (NSP) and a squat posture with the center of foot pressure (COP) intentionally shifted forward as far as possible (forward-shifted posture: FSP), and the muscle activity patterns varied significantly according to the COP location. This study focused on stepwise loading as a training strategy. Ten healthy male participants performed isometric bodyweight squats in a previous study, adopting the NSP and FSP, with three knee flexion angles (30°, 60°, and 90°). The muscle activities of the vastus medialis (VM), semitendinosus, tibialis anterior (TA), and gastrocnemius muscle lateral head were measured using surface electromyogram. This study further explored the relationship between COP shifting and knee flexion angles on electromyogram changes using three-dimensional diagrams. In one-way repeated measures analysis of variance by ranks, knee flexion angles affected the muscle activities of the VM and TA in the NSP and muscle activities of the VM in the FSP. Combining these findings, stepwise loading tasks were created to train individual target muscles. The ten male participants examined all the tasks, and the feasibility was confirmed accordingly.

The Effect of Traditional and Stabilization-Oriented Exercises on Deep Stabilization System Function in Elite Futsal Players

Article

Full-text available

Nov 2020

Background: This study aimed to compare the effect of traditional and stability-oriented strength exercises on trunk stability and deep stabilization system (DSS) activation in elite futsal players. Methods: Twenty elite futsal players (21-34 years, 180 ± 13 cm, 79 ± 15 kg) were randomly divided into a group that performed stability-oriented exercises and a group that performed traditional strength exercises. Both interventions lasted for 10 weeks and included 25 strength training sessions. Main outcome measures: The DSS pretest and posttest included the diaphragm test, trunk flexion test, back extension test, hip flexion test, intraabdominal pressure test, and a side plank test on a 1-5 point scale. Results: Both groups had similar initial test results, where the stability-oriented exercise group had significantly improved intraabdominal pressure test (p = 0.004, by lower quartile rate), trunk flexion (p = 0.036, by 0.5 grade in median), and side plank (p = 0.002, by 1 grade in median) in posttest results. Traditional exercise did not change the results of any of the included DSS function tests. Conclusions: Stabilization-oriented exercises effectively activate the functions of the DSS and should be prioritized over traditional strength exercises in injury prevention training programs. The use of stabilization-oriented exercises might prevent injury and overloading in elite futsal players.

MANUAL DO AGACHAMENTO Uma abordagem prática e científica

Book

Full-text available

May 2020

Gluteus Maximus Activation during Common Strength and Hypertrophy Exercises: A Systematic Review

Article

Full-text available

Mar 2020
J SPORT SCI MED

The gluteus maximus (GMax) is one of the primary hip extensors. Several exercises have been performed by strength and conditioning practitioners aiming to increase GMax strength and size. This systematic review aimed to describe the GMax activation levels during strength exercises that incorporate hip extension and use of external load. A search of the current literature was performed using PubMed/Medline, SportDiscuss, Scopus, Google Scholar, and Science Direct electronic databases. Sixteen articles met the inclusion criteria and reported muscle activation levels as a percentage of a maximal voluntary isometric contraction (MVIC). The exercises classified as very high level of GMax activation (>60% MVIC) were step-up, lateral step-up, diagonal step-up, cross over step-up, hex bar deadlift, rotational barbell hip thrust, traditional barbell hip thrust, American barbell hip thrust, belt squat, split squat, in-line lunge, traditional lunge, pull barbell hip thrust, modified single-leg squat, conventional deadlift, and band hip thrust. We concluded that several exercises could induce very high levels of GMax activation. The step-up exercise and its variations present the highest levels of GMax activation followed by several loaded exercises and its variations, such as deadlifts, hip thrusts, lunges, and squats. The results of this systematic review may assist practitioners in selecting exercised for strengthening GMax.

Increased strength is associated with lower trunk muscle activation during loaded back squats and dynamic body weight jumps

Article

Jul 2019

This study measured how back squat strength (1RM) affected trunk muscle activation in performing squats, squat jump (SJ) and countermovement jump (CMJ). Fifty males, completed two test sessions. Squat 1RM was tested first. Participants were assigned to three groups; (i) strong group (SG), (ii) middle group (MG) or (iii) weak group (WG), based on relative squat 1RM. Test 2, EMG data were collected for 4 trunk muscle sites; rectus abdominus, external oblique, lumbar sacral erector spinae and upper lumbar erector spinae while performing (3 reps) SJ, CMJ and squats at 65, 75 and 95% 1RM. Squat and jump phases were determined from a linear transducer and 30o tertiles for each phase, from a knee goniometer. Normalized root mean square RMS increased significantly with load for each muscle site in both squat phases. Trunk muscle activation was significantly lower in SG vs WG in eccentric and concentric squat phases. Concentric and flight phase RMS in both jumps was lower in SG vs WG. RMS increased significantly for each eccentric tertile and first concentric tertile. Greater squat strength is associated with lower trunk muscle activation in squats and jumps and trunk muscle activation was highest in the two deepest 30o squat segments. In conclusion, back squat strength training to parallel, where top of thighs are horizontal, is an effective method of developing dynamic trunk stability. This article is protected by copyright. All rights reserved.

Comparison of muscle activation and kinematics during free-weight back squats with different loads

Article

Full-text available

May 2019
PLOS ONE

Although several studies have examined the effects of performing resistance training with different percentages of one-repetition maximum (1-RM), little is known of the neuromuscular effects and kinematics of lifting low to heavy loads with maximal movement velocity. The aim of this study is to compare muscle activation and kinematics in free-weight back squats with different loads. Thirteen resistance-training males (aged 24.2 ± 2.0 years, body mass 81.5 ± 9.1 kg, height 1.78 ± 0.06 m) with 6 ± 3 years of resistance-training experience conducted squats with 30%–100% of 1-RM. Barbell kinematics and electromyographic (EMG) activity of the vastus lateralis, vastus medialis, rectus femoris, semitendinosus, biceps femoris, and gluteus maximus were measured in the upward phase of each load. With increasing loads, the barbell velocity decreased, the upward phase duration increased, and the peak velocity occurred later. The muscle activation in all muscles increased with increasing loads but was not linear. In general, similar muscle activation in the prime movers was observed for loads between 40% and 60% of 1-RM and between 70% and 90% of 1-RM, with 100% of 1-RM being superior to the other loads when the loads were lifted at maximal intended velocity. However, the timing of maximal muscle activations was not affected by the different loadings for the quadriceps, but the timing was sequential and independent of loading (rectus femoris before vastus medial before vastus lateral). Maximal activation in the gluteus and semitendinosus increased with increasing loads. This means that for muscle activation, maximal lifting velocity may compensate for increased loads, which may allow resistance-trained athletes and individuals in rehabilitation to avoid heavy loads but still get the same muscle activation.

Contemporary perspectives of core stability training for dynamic athletic performance: a survey of athletes, coaches, sports science and sports medicine practitioners

Article

Full-text available

Jul 2018

Effects of Expertise on Muscle Activity during the Hang Power Clean and Hang Power Snatch Compared to Snatch and Clean Pulls – An Explorative Analysis

Article

Full-text available

Nov 2023
J SPORT SCI MED

The purpose was to compare the electromyographic (EMG) activity of the Hang Power Clean (HPC) and Hang Power Snatch (HPS) with the Hang Clean Pull (HCP) and Hang Snatch Pull (HSP). Additionally, the influence of weightlifting expertise (beginner, advanced and elite) on EMG activity was analyzed. Twenty-seven weightlifters (beginner: n = 11, age: 23.9 ± 3.2 years, bodyweight: 75.7 ± 10.5 kg; advanced: n = 10, age: 24.8 ± 4.5 years, bodyweight: 69.4 ± 13.9 kg; elite: n = 6, age: 25.5 ± 5.2 years, bodyweight: 75.5 ± 12.5 kg) participated in this study. Participants performed two repetitions of HPC, HPS, HCP, and HSP at 50%, 70%, and 90% 1RM, respectively. The EMG activity of vastus lateralis (VL), gluteus maximus (GM), erector spinae (ES), rectus abdominis (RA) and trapezius (TZ) was recorded and normalized to the maximum voluntary isometric contraction (MVIC) of each muscle. There were significant differences in RA and ES EMG activity at 70% and 90% 1RM during HPC compared to HCP in the beginner group (p < 0.05, Hedges g = 0.50-1.06). Significant greater ES activity was observed in the beginner, advanced, and elite groups (p < 0.05, g = 0.27-0.98) during the HPS when compared to the HSP at 50-90% 1RM. TZ muscle activity was significantly greater at 50% and 70% 1RM in the HCP compared to the HPC in the elite group (p < 0.05, g = 0.61-1.08), while the beginner group reached significance only at 50% 1RM favoring HPC (p < 0.05, g = 0.38). Moreover, the EMG activity of the TZ during the HSP and HPS was significantly different only at 50% 1RM in the elite group and favored HSP (p < 0.05, g = 0.27). No differences were observed between the levels of weightlifting expertise. Based upon the results of this study, the overall pattern of EMG activity of the predominant muscles involved in HPC/HPS and the corresponding weightlifting pulling derivatives, apart from the stabilizing muscle (RA and ES), is similar at higher intensities (>70% 1RM) and expertise does not influence muscle activity.

Aerobic, muscle-strengthening, and flexibility physical activity and risks of all-cause and cause-specific mortality: a population-based prospective cohort of Korean adults

Article

Full-text available

Jun 2023
BMC PUBLIC HEALTH

Background: Studies have shown that aerobic and muscle-strengthening physical activities reduce mortality risk. However, little is known about the joint associations of the two activity types and whether other type of physical activity, such as flexibility activity, can provide similar mortality risk reduction. Objectives: We examined the independent associations of aerobic, muscle-strengthening, and flexibility physical activities with all-cause and cause-specific mortality in a population-based prospective cohort of Korean men and women. We also examined the joint associations of aerobic and muscle-strengthening activities, the two physical activity types that are recommended by the current World Health Organization physical activity guidelines. Design: This analysis included 34,379 Korea National Health and Nutrition Examination Survey 2007-2013 participants (aged 20-79 years) with mortality data linkage through December 31, 2019. Engagement in walking, aerobic, muscle-strengthening, and flexibility physical activities was self-reported at baseline. Cox proportional hazards model was performed to estimate hazard ratios (HRs) and 95% confidence intervals (CIs), adjusting for potential confounders. Results: Flexibility physical activity (≥ 5 vs. 0 d/wk) was inversely associated with all-cause (HR [95% CI] = 0.80 [0.70-0.92]; P-trend < 0.001) and cardiovascular mortality (0.75 [0.55-1.03], P-trend = 0.02). Moderate- to vigorous-intensity aerobic physical activity (≥ 50.0 vs. 0 MET-h/wk) was also associated with lower all-cause (HR [95% CI] = 0.82 [0.70-0.95]; P-trend < 0.001) and cardiovascular mortality (0.55 [0.37-0.80]; P-trend < 0.001). Similar inverse associations were observed with total aerobic physical activity, including walking. Muscle-strengthening activity (≥ 5 vs. 0 d/wk) was inversely associated with all-cause mortality (HR [95% CI] = 0.83 [0.68-1.02]; P-trend = 0.01) but was not associated with cancer or cardiovascular mortality. Compared to participants meeting the highest guidelines for both moderate- to vigorous-intensity aerobic and muscle-strengthening physical activities, those not meeting in any guideline were associated with higher all-cause (1.34 [1.09-1.64]) and cardiovascular mortality (1.68 [1.00-2.82]). Conclusions: Our data suggest that aerobic, muscle-strengthening, and flexibility activities are associated with lower risk of mortality.

Quantification of patellar tendon strain and opportunities for personalized tendon loading during back squats

Article

Full-text available

May 2023

Tendon strain during exercise is a critical regulatory factor in tendon adaptive responses and there are indications for an optimal range of strain that promotes tendon adaptation. Back squats are used to improve patellar tendon properties in sport and clinical settings. To date, the operating patellar tendon strain during back squats is unknown and current recommendations for individual exercise loading are based on the one repetition maximum (1RM). Here, we quantified patellar tendon strain during loaded back squats at 40, 60 and 80% of the 1RM and during maximum isometric knee extension contractions (MVC) using ultrasonography. Kinematics, ground reaction forces and muscle electromyographic activity were also recorded. Additionally, maximum tendon strain during the MVC and the percentage of 1RM were used as explanatory variables to estimate the individual patellar tendon strain during the squats. Strain increased with increasing 1RM loading (4.7 to 8.2%), indicating that already medium-loading back squats may provide a sufficient stimulus for tendon adaptation. The individual variability was, however, too high to generalize these findings. Yet, there was a high agreement between the individually estimated and measured patellar tendon strain (R² = 0.858) during back squats. We argue that this approach may provide new opportunities for personalized tendon exercise.

Sex Difference in Lower-limb Electromyography and Kinematics when Using Resistance Bands during a Barbell Back Squat

Article

Full-text available

Jan 2023
J HUM KINET

The aim of this study was to compare the muscle activity of the gluteus medius (GMe), gluteus maximus (GMa), biceps femoris (BF), vastus lateralis (VL), vastus medialis (VM) and erector spinae (ES) as well as medial knee displacement (MKD) while using varying stiffness resistance bands (red: 1.68 kg; black: 3.31 kg; gold: 6.44 kg) during a barbell back squat (BBS) among males and females. A total of 23 (females: 11) resistance trained people were recruited for this study. Muscle activity was measured using electromyography, and motion capture cameras tracked lower-limb kinematics and MKD. Three resistance bands were placed at the distal end of the femur while performing a BBS at their 85% repetition maximum (RM). Parametric and non-parametric statistical analyses were conducted with the alpha level of 0.05. The gold resistance band resulted in a smaller knee-width-index value (i.e., greater MKD) compared to other bands (p < 0.01). Males exhibited less MKD compared to females during the BBS for each resistance band (p = 0.04). Males produced greater VL activity when using the black and gold resistance bands during the BBS (p = 0.03). When using a gold resistance band, the GMe muscle activation was higher compared to other resistance bands (p < 0.01). VM muscle activity was reduced when using a gold resistance band compared to no band condition (p < 0.01). BF (p = 0.39) and ES (p = 0.88) muscle activity did not change when using different resistance bands. As a result, females may be at a biomechanical disadvantage when using resistance bands compared to males while performing the BBS hindering them from optimal performance.

Influence of Loads and Loading Position on the Muscle Activity of the Trunk and Lower Extremity during Squat Exercise

Article

Full-text available

Oct 2022
Int J Environ Res Publ Health

This study aimed to investigate the effect of the load and bar position on trunk and lower extremity muscle activity during squat exercise. High bar back squats (HBBS) and low bar back squats (LBBS) were performed in random order at 50%, 60%, and 70% loads of one repetition maximum by 28 experienced healthy adult men who had been performing squats for at least one year. Before the experiment, the maximal voluntary contraction of the vastus medialis, vastus lateralis, rectus femoris, biceps femoris, rectus abdominis, transverse abdominis, external oblique, and erector spinae muscles was measured by means of surface electromyography. In addition, eccentric and concentric exercises were performed for 3 s each to measure the muscle activity. There was a significant difference in muscle activity according to the load for all muscles in the eccentric and concentric phases (p < 0.05), indicating that muscle activity increased as the load increased. In addition, in the comparison between HBBS and LBBS, significant differences were shown in all lower extremity muscles and all trunk muscles except for the external oblique in the concentric phase according to the bar position (p < 0.05). HBBS showed a higher muscle activity of the lower extremity in the eccentric and concentric phases than in LBBS, while LBBS showed a higher muscle activity of the trunk muscle in the eccentric and concentric phases than in HBBS (p < 0.05). HBBS requires more force in the lower extremity than LBBS and is particularly advantageous in strengthening the muscular strength of the quadriceps. In contrast, LBBS requires more muscle activity in the trunk than HBBS and is more effective in carrying heavier loads because of the advantage of body stability. This study suggests that rehabilitation experts apply the bar position and load as important variables affecting the intensity and method of training for target muscle strengthening of the lower extremities and trunk.

Alteration in Mechanics of Overhead Squat with Wedge

Article

Full-text available

Apr 2021

Background: Altered or poor mechanics of movement creates tissue damage and stress leading to overuse injuries. It was observed that athletes with muscle imbalance had decreased playing performance and were at risk for injuries. Tight post chain structures could probably lead to altered mechanics of the overhead squat. Aim: To know whether giving a wedge beneath the heels partly nullifies the tightness in the posterior chain and improves the mechanics of the overhead squat. Methods: 30 collegiate male athletes from cricket, football and basketball were taken with a mean age of (21.37 + 2.34) years. All of them performed five overhead squats with and without a two inch wooden wedge kept beneath the heels. Results: We found shoulder flexion to improve by 3.27⁰ (+ 7. 79⁰) with the presence of a two inch wedge. Statistically significant (p = 0.024) difference was noted in shoulder flexion (46.32+ 9.58), Hip flexion (98.88+ 17.43) and (p= 0.0002), Knee flexion (114.27+ 21.79) and (p= 0.006), Ankle dorsiflexion (46.32+ 9.58) and (p= <0.0001) and the results were statistically significant. Conclusion: Based on our results, there was an increase in the range available for dorsiflexion at the ankle with the use of two inch wedge resulted in following kinematic changes: decreased shoulder flexion, increased knee flexion and increased hip flexion. The significant change in hip flexion after the use of wedge can be attributed to the shift in the center of gravity entirely.

Change in the activity of trunk and lower limb muscles during 2000-m rowing

Article

Apr 2022

This study aimed to clarify the changes in the activity of the trunk and lower limb muscles during 2000-m rowing. Ten male rowers performed a 2000-m race simulation on a rowing ergometer. Electromyography results of the abdominal muscles, back muscles, gluteus maximus (GMax), biceps femoris (BF), and rectus femoris (RF) were recorded. The electromyographic activity during the three strokes after the start (initial stage), at 1000m (middle stage), and before the end (final stage) were analyzed. From the handle position, the rowing motion was divided into five phases (early-drive, middle-drive, late-drive, early-recovery, and late-recovery). The peak activities of the abdominal muscles, back muscles, GMax, and BF in each stroke of the rowing motion were delayed at the middle and final stages compared to the initial stage (P<0.05). The peak activity of the RF was observed in the late-drive phase at the initial stage, whereas a high RF activity was observed in the middle-drive phase at the middle and final stages (P<0.05). Considering the results of the activity of the back muscles and RF, RF muscular endurance enhancement may lead to a decrease in the load on the back muscles and help prevent muscular low back pain in rowers. J. Med. Invest. 69 : 45-50, February, 2022.

Does the Overhead Squat Assessment is needed as a Movement Screening Method in Health Care Practice

Article

Jan 2019

Senthil P

Correcting movement syndromes: the role of training load and its effects on muscle activity

Article

Full-text available

Dec 2021
Sport Sci Health

PurposeCorrecting movement syndromes requires utilizing compound movements which maximally activate prime mover muscles such as the gluteus maximus (GM). This study aimed to examine prime mover and synergist muscle activity at varied training loads during the back squat, a common lower body corrective and training exercise.Methods Muscle activity was examined using surface electromyography in the GM, rectus femoris (RF), vastus lateralis (VL), biceps femoris (BF), vastus medialis (VM), and semitendinosus (ST) at six intensities (10% intervals) from 40 to 90% of one-repetition maximum (1RM) during the back squat. Repeated measures ANOVAs were utilized in statistical analysis.ResultsTraining load had a significant effect on the GM, RF, and VL (p < 0.05) during the descending phase and the VL, RF, GM, BF, and ST (p < 0.05) during the ascending phase of the back squat. The GM produced the greater muscle activity at 80% and 90% of 1RM than at 1RM during the ascending phase. The VM produced greater muscle activity at 80% of 1RM than at 1RM in both phases of the back squat. All other muscles were maximally activated at 1RM.Conclusions These results suggest that when utilizing the back squat as a corrective exercise, the prime movers VM and GM are maximally activated at training loads of 80–90% of 1RM. After this point, synergist muscles are utilized to complete the movement, potentially lowering the muscle activity of the VM or GM.

Physical Burden in Manual Patient Handling: Quantification of Lower Limb EMG Muscle Activation Patterns of Healthy Individuals Lifting Different Loads Ergonomically

Conference Paper

Jan 2021

Manual patient handling is a challenging part of daily care and leads to high mechanical loads as well as to the development of degenerative diseases, e.g. lower back pain. To prevent musculoskeletal overload effects, the use of ergonomic working techniques is essential as well as improving caregivers’ functional ability. However, most of the studies do not consider these aspects and biomechanical evaluations including dynamic electromyography (EMG) are rarely analyzed. In this work, we focus on the quantification of lower limb EMG muscle activation patterns of healthy caregiver students in an experimental setup. The extent of lifting different loads ergonomically is analyzed and similarities/dissimilarities of dynamic EMG data of three lower limb muscles are investigated via cross-correlation calculation. One of the main findings of our investigation is an indication of a more consistent mean activity of the quadriceps and hamstring musculature, as the load to be lifted increases. Furthermore, we found an intra- as well as an interindividual similarity of EMG muscle activation patterns regarding time and shape of the signals generated during all of the conducted lifting tasks with a predominantly high cross-correlation coefficient for the selected muscles of the lower limb.

A systematic review on the muscular activation on the lower limbs with five different variations of the deadlift exercise

Article

Full-text available

Jan 2021

The deadlift is one of the most widely used resistance exercises by different types of trainees and with different aims including aesthetics, performance and health. There are numerous variations of the deadlift exercise which have different effects on the exercise biomechanics and muscular activation. The main objective of this research was to systematically review the literature looking forward to gathering data on the muscular activation on the lower limbs with different variations of the deadlift exercise (conventional, sumo, Romanian, straight legs and hex-bar). 19 articles met the inclusion criteria and were included in the analysis. Quality of the articles was assessed through the PEDro scale. Main findings were that deadlift is a posterior-chain dominant exercise. Changes in activation between the variations majorly depend on the hip flexion in relation to the knee flexion. For instance, the straight-legs deadlift does not involve knee flexion and mainly activates hip extensors. Other factors such as the distance between the load and the centre of mass, the knee flexion planes, or the total intensity also condition the muscular activation. For example, the hex-bar deadlift allows the subject being in alignment with the load and performing the exercise with relatively vertical back, which provokes an increase on the activation of the knee extensors. In conclusion, this study may help the strength and conditioning professionals and practitioners with the exercise selection depending on the muscular targets and the individual characteristics of the athlete. Keywords: Electromyographic activity; Resistance exercise; Quadriceps; Gluteus; Hamstrings; Calves.

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

Article

Full-text available

Dec 2020

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.

Validity and reliability of a flywheel squat test in sport

Article

Sep 2020
J SPORT SCI

word count: 200 13 Text-only word count: 4000 14 15 ABSTRACT 16 The aims of this study were to examine the test-retest reliability and construct validity of the 17 flywheel (FW)-squat test. Twenty male amateur team sports athletes (mean±SD: age 23±3 18 years) completed one familiarization session and two similar testing sessions including: FW-19 squat test with an inertial load of 0.061 kg. m 2 , standing long jump (SLJ), countermovement 20 jump (CMJ) and 5-m change of direction (COD-5m) tests, and isokinetic strength assessments 21 of the knee extensor and flexor muscles. Test-retest reliability was assessed with intraclass 22 correlation coefficient (ICC) and coefficient of variation (CV) of data collected. Construct 23 validity was determined as the degree of relationships between the FW-squat test outputs and 24 both athletic tests and isokinetic assessments scores computed with Pearson's correlation 25 coefficients. Excellent relative (ICC=0.94-0.95) and acceptable absolute (CV=5.9%-6.8%) 26 reliability scores were found for both concentric and eccentric power outputs collected during 27 the FW-squat test. The same outputs showed moderate to large positive correlations with 28 concentric and eccentric knee extensor and flexor muscle peak force values (r range: 0.465-29 0.566) measured during the isokinetic test. The FW-squat test is a valid and reliable test to 30 assess lower limb performance given its correlation with isokinetic test, as well as its excellent 31 relative and acceptable absolute reliability. 32

Electromyographic activity in the gluteus medius, gluteus maximus, biceps femoris, vastus lateralis, vastus medialis and rectus femoris during the Monopodal Squat, Forward Lunge and Lateral Step-Up exercises

Article

Full-text available

Apr 2020
PLOS ONE

The Monopodal Squat, Forward Lunge and Lateral Step-Up exercises are commonly performed with one's own body weight for rehabilitation purposes. However, muscle activity evaluated using surface electromyography has never been analyzed among these three exercises. Therefore, the objectives of the present study were to evaluate the amplitude of the EMG activity of the gluteus medius, gluteus maximus, biceps femoris, vastus lateralis, vastus medialis and rectus femoris muscles in participants performing the Lateral Step-Up, Forward Lunge and Monopodal Squat exercises. A total of 20 physically active participants (10 men and 10 women) performed 5 repetitions at 60% (5 repetition maximum) in each of the evaluated exercises. The EMG amplitude was calculated in percentage of the maximum voluntary contraction. The Monopodal Squat exercise showed a higher EMG activity (p ≤ 0.001) in relation to the Lateral Step-Up and Forward Lunge exercises in all of the evaluated muscles (d > 0.6) except for the rectus femoris. The three exercises showed significantly higher EMG activity in all of the muscles that were evaluated in the concentric phase in relation to the eccentric one. In the three evaluated exercises, vastus lateralis and vastus medialis showed the highest EMG activity, followed by gluteus medius and gluteus maximus. The Monopodal Squat, Forward Lunge and Lateral Step-Up exercises not only are recommended for their rehabilitation purposes but also should be recommended for performance objectives and strength improvement in the lower limbs.

The effect of elevating the heels on spinal kinematics and kinetics during the back squat in trained and novice weight trainers

Article

Full-text available

Mar 2020

This research assessed the influence of various heel elevation conditions on spinal kinematic and kinetic data during loaded (25% and 50% of body weight) high-bar back squats. Ten novice (mass 67.6 ± 12.4 kg, height 1.73 ± 0.10 m) and ten regular weight trainers (mass 66.0 ± 10.7 kg, height 1.71 ± 0.09 m) completed eight repetitions at each load wearing conventional training shoes standing on the flat level floor (LF) and on an inclined board (EH). The regular weight training group performed an additional eight repetitions wearing weightlifting shoes (WS). Statistical parametric mapping (SPM1D) and repeated measures analysis of variance were used to assess differences in spinal curvature and kinetics across the shoe/floor conditions and loads. SPM1D analyses indicated that during the LF condition the novice weight trainers had greater moments around L4/L5 than the regular weight trainers during the last 20% of the lift (P < 0.05), with this difference becoming non-significant during the EH condition. This study indicates that from a perspective of spinal safety, it appears advantageous for novice weight trainers to perform back squats with their heels slightly elevated, while regular weight trainers appear to realize only limited benefits performing back squats with either EH or WS.

Maximal Strength, Muscle Activation, and Bar Velocity Comparisons Between Squatting With a Traditional or Safety Squat Bar

Article

Full-text available

Feb 2020

Vantrease, WC, Townsend, JR, Sapp, PA, Henry, RN, and Johnson, KD. Maximal strength, muscle activation, and bar velocity comparisons between squatting with a traditional or safety squat bar. J Strength Cond Res XX(X): 000-000, 2020-The purpose of this study was to compare strength, muscle activation, and bar velocity between the traditional (TRAD) and safety squat bar (SSB) back squat. Thirty-two men (21.94 ± 3.1 years, 1.78 ± 0.8 m, 81.7 ± 10.1 kg) volunteered to complete this randomized, crossover-design study. Subjects completed 2 separate 1 repetition maximum (1RM) sessions using either the TRAD or SSB. Subsequently, subjects completed 1 session of 3 repetitions at 65 and 85% of their 1RM for each squat condition (SSB & TRAD). Peak muscle activation of 7 muscles from the lower body and trunk was recorded through surface electromyography (EMG), and mean velocity (MV) was recorded by a linear transducer. Electromyography and MV were analyzed by a 2 × 2 (bar × load) repeated-measures analysis of variance. A Pearson correlation was used to determine the relationship of 1RM load between bars. Squat 1RM was significantly higher (p < 0.001; 11.6%) for TRAD (144.7 kg) compared with SSB (128.8 kg), and a strong correlation (r = 0.94) was observed between 1RM values of each bar. A significant main effect was seen in EMG (p < 0.001) and MV for load (p < 0.001). No significant bar × load interaction was observed between conditions for any EMG or bar velocity measure (p > 0.05). The SSB produces similar muscle activation and bar velocities compared with the TRAD at relative intensities. However, absolute loads should be adjusted when changing squat bars during a training cycle.

Selection of Resistance Exercises for Older Individuals: The Forgotten Variable

Article

Full-text available

Jun 2020
SPORTS MED

Resistance training has been widely recommended as a strategy to enhance the functional autonomy and quality of life in older individuals. Among the variables that comprise a training session, the selection of exercises stands out as an important consideration for the elderly. Although a wide range of resistance exercise options exists, current guidelines generally do not indicate which exercises should be included and which muscles should be prioritized when prescribing training for older individuals. Therefore, given the lack of evidence-based information on the topic, this paper endeavors to establish recommendations to help guide the prescription of resistance exercises for older adults.

Relationship Between Lower Extremity Extensor Strength and Wall Squat Performance

Article

Full-text available

Nov 2019

Evaluation of Muscle Activities During Different Squat Variations Using Electromyography Signals

Chapter

Full-text available

Jan 2020

The importance of Electromyography (EMG) signals analysis with advanced methodologies is increasing in biomedics, clinical diagnosis and biomechanics and it becomes a required practice for many scientists from both health and engineering fields. The squat is a very important exercise for improving athletic performance and for prevention and rehabilitation of injuries. It has many different variations which are supposedly focusing on different muscles. We aimed to compare vastus medialis, rectus femoris, vastus lateralis, gluteus maximus, semitendinosus, biceps femoris and erector spinae EMG activities during popular squat variations while the participants (14 healthy males, 23.7 ± 2.7 years-old) were performing 6 repetitions of front squat, back squat, hack squat, sumo squat and zercher squat with 60% of the 1 repetition maximum loading. Muscle EMG activities during different variations were compared by using Repeated measures ANOVA. The highest rectus femoris, vastus lateralis and vastus medialis EMG activities were observed during front squat with a significant difference with Zercher squat. EMG activities of Erector spinae and semitendinosus during Hack squat were significantly lower than all other squat variations (p < 0.05). These findings may suggest that front squat may be chosen to focus on quadriceps muscles while Hack squat may be a good choice for better knee and spinal stabilization.

Aspectos sobre seleção de exercícios resistidos em idosos

Article

Sep 2019

Resistance exercise has been widely recommended for elderly population, since this type of exercise induces important health benefits, especially to improve functional capacity and preserve muscle mass, thus reflecting on the quality of life of older individuals. Among the several components of the resistance exercises the selection of movements to be performed is one of the most important and must be carefully analyzed. Although there may be a wide range of options, the most important recommendations do not specifically indicate the movements that should be included and muscle groups that should be prioritized when prescribing resistance exercise for the elderly. Therefore, considering that there is a lack of information for the Physical Education professional about the topic, this study was developed to support the choices of the movements that will compose the resistance exercise program for the elderly. The study was carried out by compiling and analyzing assumptions and scientific evidences related to resistance exercises and needs of elderly individuals. In conclusion, the choice of movements should be based on the principles of kinesiology, the needs of the elderly, muscle action and exercise safety in order to obtain beneficial results for general health and attenuate possible risks.Keywords: Exercise. Aging. Physical Exertion.ResumoO exercício resistido vem sendo amplamente recomendado para população idosa, uma vez que esse tipo de exercício físico induz a importantes benefícios para saúde; sobretudo, no aprimoramento da capacidade funcional e na preservação da massa muscular, refletindo, desse modo, na qualidade de vida do indivíduo idoso. Dentre os diversos componentes dos exercícios resistidos, a seleção dos movimentos a serem executados é um dos mais importantes e deve ser cuidadosamente analisado. Embora possa existir vasta gama de opções, as principais recomendações não indicam especificamente os movimentos que devem ser incluídos e os grupos musculares que devem ser priorizados nos programas de exercícios resistidos. Portanto, considerando haver uma lacuna de informações sobre o tema, o estudo foi realizado com intuito de subsidiar a seleção dos movimentos que deverão compor os programas de exercícios resistidos para idosos. O estudo foi realizado mediante compilação e análise de pressupostos e evidências científicas referentes aos exercícios resistidos e as necessidades dos idosos. Concluiu-se que a seleção dos movimentos deve ser baseada nos princípios da cinesiologia, nas necessidades dos idosos, na ação muscular e na segurança de execução para se alcançar resultados benéficos para saúde em geral e atenuar possíveis riscos.Palavras-chave: Exercício. Envelhecimento. Esforço Físico.

Resultant Reactions in the Hip, Knee and the L5-S1 Joint During the Back Squat with Variation External Loads

Chapter

Aug 2019

The research work aimed to identify and analyse reactions in the joints of the lower limb as well as in the intervertebral joints of the lumbar spine when lifting weights and making a squat. The determination of loads of the skeletal-muscular system involved the performance of simulations in the AnyBody software programme. Input data used in the research-related tests came from the tests concerning the kinematics of weightlifting by a weightlifter. The use of mathematical modelling and static optimisation methods made it possible to identify resultant responses in the joints in individual positions of a squat made under various external loads. The highest resultant responses in all of the joints subjected to analysis were identified at an angle of \(135^{\circ }\) in knee joints. As a result, it is important to pay attention during training not to stop moving during an exercise at the above-named angle.

Interpreting Signal Amplitudes in Surface Electromyography Studies in Sport and Rehabilitation Sciences

Preprint

Sep 2017

Surface electromyography (sEMG) is a popular research tool in sports and rehabilitation sciences. Common study designs include the comparison of sEMG amplitudes collected from different muscles as participants perform various exercises and techniques under different loads. Based on such comparisons, researchers attempt to draw conclusions concerning the neuro- and electrophysiological underpinning of force production, and hypothesize about possible longitudinal adaptations, such as strength and hypertrophy. However, such conclusions are frequently unsubstantiated and unwarranted. Hence, the goal of this review is to discuss what can and cannot be inferred from comparative research designs as it pertains to both the acute and longitudinal outcomes. General methodological recommendations are made, gaps in the literature are identified, and lines for future research to help improve the applicability of sEMG are suggested.

Can we spread the risk? A demand-share perspective to sustained hamstring health

Article

Jun 2018

A synergistic algebra appears to be at play in the body, sustaining an athlete's performance in the face of competing demands, yet these may be associated with risk. Akin to the employment of redundancy within engineering sciences, we suggest this phenomenon can be strategically harnessed through careful consideration of programme scheduling, contraction profiles and exercise design to share the work amongst other tissues and access the plasticity evident within the movement system. Tabled 1 SynergistsPrimary Focus Biceps Femoris Long Head, Semimembranosus Sagittal plane, eccentric force production, fascicle elongation Semitendinosus, Biceps Femoris Short Head, Popliteus Sagittal and transverse plane fatigue tolerance Gluteus Maximus Sagittal plane, concentric force production and fascicle shortening Adductor Magnus Tri-planar eccentric force production, fascicle elongation Gastrocnemius Increased stiffness facilitating enhanced force transfer and tendon contribution Oblique abdominals Tri-planar eccentric force production within small amplitudes of muscle length around lumbo-pelvic neutral alignment Specific muscles in the management of hamstring injuries for repeat sprint athletes (footballers). • Open table in a new tab

숙련자의 스쿼트 중량 증가에 따라 나타나는 무릎 안쪽 움직임에 대한 운동역학적 연구

Article

Jul 2023

The Barbell Back Squat Exercise

Article

Jul 2023

Does Reactive Neuromuscular Training Increase Gluteal Musculature Activation During Squatting Movements? A Critically Appraised Topic

Article

Jan 2022

Clinical Question : Does reactive neuromuscular training (RNT) increase gluteal muscle activation during squatting movements? Clinical Bottom Line : The current best evidence suggests RNT may result in acute increases of gluteus maximus and gluteus medius muscle activation when performing the barbell back squat exercise; however, the findings were inconsistent and unclear for other types of squatting movements. Grades B and D evidence exists on the effects of RNT to increase gluteus maximus and medius muscle activation, respectively, during squatting movements. Given the methodological differences and mixed findings reported in this critically appraised topic, practitioners should carefully consider whether using RNT would be appropriate for a given clinical scenario.

Differences in Muscle Activity and Kinetics Between the Goblet Squat and Landmine Squat in Men and Women

Article

Aug 2021
J STRENGTH COND RES

Collins, KS, Klawitter, LA, Waldera, RW, Mahoney, SJ, and Christensen, BK. Differences in muscle activity and kinetics between the goblet squat and landmine squat in men and women. J Strength Cond Res XX(X): 000-000, 2021-Squat exercise variations are widely used and extensively researched. However, little information exists on the goblet squat (GBS) and landmine squat (LMS) and differences between men and women. This study investigated the differences in muscle activity and kinetics between the GBS and the LMS in 16 men and 16 women. Five repetitions of each squat type were performed loaded at 30% of their body mass. Vertical and anteroposterior ground reaction forces for the eccentric and concentric phases and peak vertical force were recorded with a force plate. Electromyographic (EMG) signals were recorded for the vastus medialis (VM), vastus lateralis (VL), semitendinosus (ST), and biceps femoris (BF). Normalized mean EMG values and ground reaction forces were analyzed with repeated measures analysis of variance (p < 0.05). Significant main effects for squat condition and sex were found. The LMS reduced activity in the quadriceps (VM and VL) muscles and vertical forces, while increasing posterior horizontal forces. In the LMS, men showed decreased ST activity, whereas women had decreased BF activity. Women exhibited greater quadriceps activity in both the GBS and LMS and greater ST in the LMS. Women also produced greater eccentric vertical force in both the GBS and LMS and less posterior horizontal forces in the LMS. The LMS may be useful to balance hamstring to quadriceps activity, increase horizontal loading, and reduce vertical loading. Conversely, the GBS can better target quadriceps activity and increase vertical loading. Sex differences should be considered for training programs that include the GBS and LMS.

Front Squat Increases Lumbar Lordosis Compared to Back Squat without Changing Lower Limb and Trunk Muscles Activity at the Same Absolute Barbell Weight

Article

Full-text available

Apr 2021

Compared to back squat (BSQ), front squat (FSQ) exhibits a smaller anterior trunk tilt to avoid dropping a barbell held in front of the body, which may lead to increase trunk extension and lumbar lordosis. This study aimed to clarify the differences in the lumbar lordosis angle, anterior trunk tilt angle, and muscle activities of the lower limb and trunk between the FSQ and BSQ. Ten healthy men participated in this study. The participants performed parallel and full FSQ and BSQ. The SQ motion was recorded using three-dimensional motion-capture cameras, and divided into four phases. The lumbar lordosis angle, anterior trunk tilt angle, and lower limb and trunk muscles activity were analyzed. Independent t-tests were used to compare the minimum lumbar lordosis angle and maximum anterior trunk tilt angle between the FSQ and BSQ in each SQ depth. Two-way analysis of variances (barbell positions × phases) were used to compare the mean lumbar lordosis angle and each muscle activity in each phase between the FSQ and BSQ in each SQ depth. The lumbar lordosis angle was significantly larger during FSQ than during BSQ at the minimum value and the mean value in each phase, regardless of depths (P < 0.05). There were no significant differences in the maximum anterior trunk tilt angle and muscle activities of the lower limb and trunk between the FSQ and BSQ in both depths (P > 0.05). These results are the basis for proposing an appropriate SQ style using the FSQ and BSQ to prevent low back pain.

Muscle activation varies between high-bar and low-bar back squat

Article

Full-text available

Jun 2020

Background Differences in the muscular activity between the high-bar back squat (HBBS) and the low-bar back squat (LBBS) on the same representative group of experienced powerlifters are still scarcely investigated. The main purpose of the study was to compare the normalized bioelectrical activity and maximal angles within single homogeneous group between the HBBS and LBBS for 60% one repetition maximum (1RM), 65% 1RM and 70% 1RM. Methods Twelve healthy men (age 24.3 ± 2.8 years, height 178.8 ± 5.6 cm, body mass 88.3 ± 11.5 kg), experienced in powerlifting performed HBBS and LBBS with comparable external loads equal 60% 1RM, 65% 1RM, and 70% 1RM. Electromyography (EMG) signals of muscle groups were synchronously recorded alongside kinematic data (joints angle) by means of a motion capture system. Results EMG activity during eccentric phase of squat motion were significantly higher during LBBS than in HBBS for all selected muscles (60% 1RM and 65% 1RM) (p < 0.05). All examined muscles were more activated during concentric phase of the squat cycle (p < 0.05). In the concentric phase, significant differences between the loads were generally not observed between just 5% 1RM change in load level for LBBS. Conclusions Our results confirmed significant differences in muscles activation between both squat techniques. Muscle activity during eccentric phase of squat motion were significantly higher during LBBS than HBBS. The differences are crucial for posterior muscle chain during eccentric phase of squat cycle.

Influencia de las lesiones previas en los patrones fundamentales del movimiento en jugadoras profesionales de fútbol. [Influence of previous injuries on fundamental movement patterns in professional female soccer players].

Article

Full-text available

Apr 2020

En el alto nivel la detección del riesgo de lesión resulta crucial para alcanzar el éxito deportivo. Para ello, los equipos técnicos suelen buscar herramientas sencillas, económicas y que doten de mucha información, tales como los tests funcionales y registros de lesiones. Por lo tanto, los objetivos de este estudio fueron describir tanto las lesiones previas como las compensaciones manifestadas por jugadoras de fútbol en patrones básicos de movimiento, así como analizar la relación entre estas lesiones y los patrones motores fundamentales analizados. En este estudio de cohortes retrospectivo participaron 16 jugadoras de fútbol de segunda división [Edad: 22±4,11 años; práctica federada: 10±4,49 años]. Se evaluaron los patrones motores básicos mediante la Valoración Funcional Básica (VAFB) y se cumplimentó un cuestionario sobre las lesiones de la temporada anterior. Nueve jugadoras (56,25%) sufrieron alguna lesión, de entre las cuales ocho (88,89%) se localizaron en el miembro inferior y la mayoría de lesiones se produjeron por sobreuso, sin contacto (n=7). Los porcentajes medios de compensaciones y asimetrías en la VAFB fueron de 65,79%±11,80 y 15,30%±4,82, respectivamente. Los resultados de la valoración funcional fueron ligeramente mejores para las jugadoras que no sufrieron lesión, aunque las diferencias no fueron significativas [t=-,605; p=,555]. Los resultados de la VAFB podrían ser empleados en el diseño de programas preventivos individualizados en fútbol femenino.

Influencia de las lesiones previas en los patrones fundamentales del movimiento en jugadoras profesionales de fútbo

Article

Full-text available

Apr 2020

Influencia de las lesiones previas en los patrones fundamentales del movimiento en jugadoras profesionales de fútbol Influence of previous injuries on fundamental movement patterns in professional female soccer players Resumen En el alto nivel la detección del riesgo de lesión resulta crucial para alcanzar el éxito deportivo. Para ello, los equipos técnicos suelen buscar herramientas sencillas, económicas y que doten de mucha información, tales como los tests funcionales y registros de lesiones. Por lo tanto, los objetivos de este estudio fueron describir tanto las lesiones previas como las compensaciones manifestadas por jugadoras de fútbol en patrones bási-cos de movimiento, así como analizar la relación entre estas lesiones y los patrones motores fundamentales analizados. En este estudio de cohortes retrospectivo participaron 16 jugadoras de fútbol de segunda división [Edad: 22±4,11 años; práctica federada: 10±4,49 años]. Se evaluaron los patrones motores básicos mediante la Valoración Funcional Básica (VAFB) y se cumplimentó un cuestionario sobre las lesiones de la temporada anterior. Nueve jugadoras (56,25%) sufrieron alguna lesión, de entre las cuales ocho (88,89%) se localizaron en el miembro inferior y la mayoría de lesiones se produjeron por sobreuso, sin contacto (n=7). Los porcentajes medios de compensaciones y asimetrías en la VAFB fueron de 65,79%±11,80 y 15,30%±4,82, respectivamen-te. Los resultados de la valoración funcional fueron ligeramente mejores para las jugadoras que no sufrieron lesión, aunque las diferencias no fueron significativas [t=-,605; p=,555]. Los resultados de la VAFB podrían ser empleados en el diseño de programas preventivos individualizados en fútbol femenino. Palabras clave: patrón de movimiento; lesión, Valoración Funcional Básica; fútbol femenino; calidad de movimiento. Abstract At the high level, the detection of the risk of injury is crucial for sporting success. For this purpose, technical teams often look for simple, economical and informative tools, such as functional tests and injury records. Therefore, the objectives of this study were to describe both the previous injuries and the compensations expressed by female football players in basic movement patterns, as well as to analyse the relationship between these injuries and the fundamental motor patterns analysed. This retrospective cohort study involved 16 second division female football players [Age: 22±4.11 years; federated practice: 10±4.49 years]. Basic motor patterns were evaluated using Basic Functional Assessment (BAFA) and a questionnaire on injuries from the previous season was completed. Nine players (56.25%) suffered some injury, among which eight (88.89%) were located in the lower limb and the majority of injuries were caused by overuse, without contact (n=7). The mean percentages of compensations and asymmetries in the VAFB were 65.79%±11.80 and 15.30%±4.82, respectively. Functional assessment results were slightly better for players who did not suffer injury, although the differences were not significant [t=-,605; p=,555]. The results of the VAFB could be used in the design of individualized preventive programs in women's soccer.

Mobile Test of Manual Dexterity in the Diagnostics of Frail Geriatric Patients – Pilot Study

Chapter

Aug 2019

Mortality rate increases exponentially with people’s age. They gather age-related diseases and become ‘frail’, i.e. increasingly vulnerable to various stressors. The gold standard to evaluate the severity of upper limb motor symptoms is to use the UPDRS-part III (motor examination) yet it is proven that simple tests of manual dexterity can identify persons at high risk for neurodegenerative diseases. The aim of this study is to evaluate a novel, objective, observer-independent and assistance-independent tablet device-based method which could be helpful in the upper limb function diagnostics designed for telemedicine technology and frailty assessment. The test employs a tablet and a fixed-height obstacle. The patient is required to move his/her hand above the obstacle and touch the round fields displayed on the tablet. The test is performed for 30 s, as fast as possible, using pointing finger of the dominating hand. Several parameters are registered using the tablet. In the study, the test is evaluated in the group inpatients of geriatric hospital separated into Frail (14 patients) and Control (14 patients) groups. The patients in the Control group are featuring (Mann-Whitney U-test, p-value < 0.05) more correct touches (23.4±8.2 vs. 17.1±12.4) than the members of the Frail group. The reaction time and mean time between touches in Control group is shorter than in the Frail group (respectively Mann-Whitney U-test and Student’s t-test; p-value < 0.05).

Effect of Loading Devices on Muscle Activation in Squat and Lunge

Article

Jan 2019

Context: Squats and lunges are common exercises frequently applied in muscle-strengthening and therapeutic exercises. The loading devices are often used to increase the training intensity. Objective: To determine the effect of loading devices on muscle activation in squat and lunge and to compare the differences in muscle activation between squat and lunge. Design: Cross-sectional cohort. Participants: Nineteen healthy, male, recreationally active individuals without a history of lower limb injury. Interventions: Each participant performed 10 repetitions of a squat under 5 conditions: unloaded, barbell, dumbbell, loaded vest, and kettlebell, and 10 repetitions of a lunge under 4 conditions: unloaded, barbell, dumbbell, and loaded vest. Main outcome measures: The electromyography signals of quadriceps, hamstrings, tibialis anterior, gastrocnemius lateralis and medialis were measured. One-way repeated-measure analysis of variance was used to compare the difference among different loading conditions. Paired t test was used to compare the difference between squat and lunge. Results: The muscle activation in the loaded conditions was significantly higher than that in nonloaded conditions in squat and lunge. Compared with the barbell, dumbbell, and loaded vest conditions, the semitendinosus showed significantly higher activation, and the tibialis anterior showed significantly lower activation in kettlebell condition in squat. No significant difference in muscle activation was found among barbell, dumbbell, and kettlebell conditions in lunge. In addition, quadriceps and hamstring activities were significantly higher in lunge than in squat. Conclusions: Muscle activation was affected by the loading devices in squat but not affected in lunge. Kettlebell squat could be suggested for targeting in strengthening medial hamstring. Progressive strengthening exercise could be recommended from squat to lunge based on sequential activation level.

A Biomechanical Analysis of Straight and Hexagonal Barbell Deadlifts Using Submaximal Loads

Article

Full-text available

Jul 2011
J STRENGTH COND RES

The purpose of the investigation was to compare the kinematics and kinetics of the deadlift performed with 2 distinct barbells across a range of submaximal loads. Nineteen male powerlifters performed the deadlift with a conventional straight barbell and a hexagonal barbell that allowed the lifter to stand within its frame. Subjects performed trials at maximum speed with loads of 10, 20, 30, 40, 50, 60, 70, and 80% of their predetermined 1-repetition maximum (1RM). Inverse dynamics and spatial tracking of the external resistance were used to quantify kinematic and kinetic variables. Subjects were able to lift a heavier 1RM load in the hexagonal barbell deadlift (HBD) than the straight barbell deadlift (SBD) (265 ± 41 kg vs. 245 ± 39 kg, p < 0.05). The design of the hexagonal barbell significantly altered the resistance moment at the joints analyzed (p < 0.05), resulting in lower peak moments at the lumbar spine, hip, and ankle (p < 0.05) and an increased peak moment at the knee (p < 0.05). Maximum peak power values of 4,388 ± 713 and 4,872 ± 636 W were obtained for the SBD and HBD, respectively (p < 0.05). Across the submaximal loads, significantly greater peak force, peak velocity and peak power values were produced during the HBD compared to during the SBD (p < 0.05). The results demonstrate that the choice of barbell used to perform the deadlift has a significant effect on a range of kinematic and kinetic variables. The enhanced mechanical stimulus obtained with the hexagonal barbell suggests that in general the HBD is a more effective exercise than the SBD.

An Electromyographical Comparison of Trunk Muscle Activity During Isometric Trunk and Dynamic Strengthening Exercises

Article

Full-text available

Jan 2011
J STRENGTH COND RES

The purpose of this study was to compare rectus abdominis and erector spinae muscle activity during isometric (prone bridge [PB] and superman [SM]) and dynamic strengthening exercises (back squat, front squat [FS], and military press). Participants (n = 10, age 21.8 ± 2.6 years; body mass 82.65 ± 10.80 kg, 174.5± 7.2 cm), performed each exercise in a randomized order, using a repeated-measures design. Electromyographical (EMG) activity (sampling at 2,000 Hz) of the rectus abdominis (RA) and the erector spinae (ES) muscles was recorded throughout the duration of the exercises. Intraclass correlations demonstrated the highest levels of reliability for muscle activity during the isometric exercises; however, all exercises demonstrated high level of reliability (r = 0.764-0.998, p ≤ 0.01). The PB demonstrated significantly greater (p < 0.01) RA activity compared to all other exercises. The ES activity was significantly (p < 0.01) greater during the FS (1.010 ± 0.308 root mean square value [RMS (V)]) and SM (0.951 ± 0.217 RMS[V]) and compared to all other exercises, although there was no significant difference (p > 0.05) between the FS and the SM exercise. The PB may be the most suitable exercise for strengthening the RA, compared to dynamic exercises at a low to moderate load, because of a higher level of muscle activity. The FS may be a useful alternative to isometric exercises when strengthening the ES, because it results in slightly higher muscle activity levels when using only a light to moderate load. Because of the dynamic nature of the FS, this may also be more beneficial in transferring to activities of daily living and sporting environments.

Effect of Instability and Resistance on Unintentional Squat-Lifting Kinetics

Article

Full-text available

Jan 2008

Resistance training while using an instability-training device is known to increase activation of stabilizing muscle groups while decreasing the force generated by the prime movers during isometric contractions. Purpose: To investigate differences in squat kinetics during dynamic resistance training in an increasingly unstable training environment. Fourteen active men participated in this study. In each testing session, each participant performed 3 repetitions of squats with a 10-repetition maximum (10-RM) resistance, 40% of their 10-RM resistance, and 20.45 kg. The 3 testing session consisted of standing on a stable floor, foam pads, or BOSU balls. All repetitions were recorded with an optical encoder to record barbell kinetics. The transition from stable (floor) to very unstable (BOSU) resulted in high likelihoods (>75%) of clinically meaningful differences ranging from small to large (effect size [ES] 0.31-1.73) in factors relating to concentric kinetics, eccentric power, and squat depth, regardless of the resistance used for training. There were also likely differences at the heaviest resistance in peak concentric power (stable to foam: ES 2.06; foam to BOSU: ES 0.38), eccentric power (stable to foam: ES 1.88; foam to BOSU: ES 0.74), and squat depth (stable to foam: ES 0.50; foam to BOSU: ES 0.67). Resistance training in an unstable environment at an intensity sufficient to elicit strength gains of the prime movers results in deleterious effects in concentric squat kinetics and squat technique. Such observations are particularly evident on very unstable platforms.

A Biomechanical Comparison of Back and Front Squats in Healthy Trained Individuals

Article

Full-text available

Dec 2008
J STRENGTH COND RES

The strength and stability of the knee plays an integral role in athletics and activities of daily living. A better understanding of knee joint biomechanics while performing variations of the squat would be useful in rehabilitation and exercise prescription. We quantified and compared tibiofemoral joint kinetics as well as muscle activity while executing front and back squats. Because of the inherent change in the position of the center of mass of the bar between the front and back squat lifts, we hypothesized that the back squat would result in increased loads on the knee joint and that the front squat would result in increased knee extensor and decreased back extensor muscle activity. A crossover study design was used. To assess the net force and torque placed on the knee and muscle activation levels, a combination of video and force data, as well as surface electromyographic data, were collected from 15 healthy trained individuals. The back squat resulted in significantly higher compressive forces and knee extensor moments than the front squat. Shear forces at the knee were small in magnitude, posteriorly directed, and did not vary between the squat variations. Although bar position did not influence muscle activity, muscle activation during the ascending phase was significantly greater than during the descending phase. The front squat was as effective as the back squat in terms of overall muscle recruitment, with significantly less compressive forces and extensor moments. The results suggest that front squats may be advantageous compared with back squats for individuals with knee problems such as meniscus tears, and for long-term joint health.

Stance width and bar load effects on leg muscle activity during the parallel squat

Article

Full-text available

Apr 1999

Altering foot stance is often prescribed as a method of isolating muscles during the parallel squat. The purpose of this study was to compare activity in six muscles crossing the hip and/or knee joints when the parallel squat is performed with different stances and bar loads. Nine male lifters served as subjects. Within 7 d of determining IRM on the squat with shoulder width stance, surface EMG data were collected (800 Hz) from the rectus femoris, vastus medialis, vastus lateralis, adductor longus, gluteus maximus, and biceps femoris while subjects completed five nonconsecutive reps of the squat using shoulder width, narrow (75% shoulder width), and wide (140% shoulder width) stances with low and high loads (60% and 75% 1RM, respectively). Rep time was controlled. A goniometer on the right knee was used to identify descent and ascent phases. Integrated EMG values were calculated for each muscle during phases of each rep, and the 5-rep means for each subject were used in a repeated measures ANOVA (phase x load x stance, alpha = 0.05). For rectus femoris, vastus medialis, and vastus lateralis, only the load effect was significant. Adductor longus exhibited a stance by phase interaction and a load effect. Gluteus maximus exhibited a load by stance interaction and a phase effect. Biceps femoris activity was highest during the ascent phase. The results suggest that stance width does not cause isolation within the quadriceps but does influence muscle activity on the medial thigh and buttocks.

Trunk Muscle Activity Increases With Unstable Squat Movements

Article

Full-text available

Mar 2005

The objective of this study was to determine differences in electromyographic (EMG) activity of the soleus (SOL), vastus lateralis (VL), biceps femoris (BF), abdominal stabilizers (AS), upper lumbar erector spinae (ULES), and lumbo-sacral erector spinae (LSES) muscles while performing squats of varied stability and resistance. Stability was altered by doing the squat movement on a Smith machine, a free squat, and while standing on two balance discs. Fourteen male subjects performed the movements. Activities of the SOL, AS, ULES, and LSES were highest during the unstable squat and lowest with the Smith machine protocol (p < 0.05). Increased EMG activity of these muscles may be attributed to their postural and stabilization role. Furthermore, EMG activity was higher during concentric contractions compared to eccentric contractions. Performing squats on unstable surfaces may permit a training adaptation of the trunk muscles responsible for supporting the spinal column (i.e., erector spinae) as well as the muscles most responsible for maintaining posture (i.e., SOL).

Trunk Muscle Activation During Dynamic Weight-Training Exercises and Isometric Instability Activities

Article

Full-text available

Dec 2007
J STRENGTH COND RES

The purpose of this study was to examine the extent of activation in various trunk muscles during dynamic weight-training and isometric instability exercises. Sixteen subjects performed squats and deadlifts with 80% 1 repetition maximum (1RM), as well as with body weight as resistance and 2 unstable calisthenic-type exercises (superman and sidebridge). Electromyographic (EMG) activity was measured from the lower abdominals (LA), external obliques (EO), upper lumbar erector spinae (ULES), and lumbar-sacral erector spinae (LSES) muscle groups. Results indicated that the LSES EMG activity during the 80% 1RM squat significantly exceeded 80% 1RM deadlift LSES EMG activity by 34.5%. The LSES EMG activity of the 80% 1RM squat also exceeded the body weight squat, deadlift, superman, and sidebridge by 56, 56.6, 65.5, and 53.1%, respectively. The 80% 1RM deadlift ULES EMG activity significantly exceeded the 80% 1RM squat exercise by 12.9%. In addition, the 80% 1RM deadlift ULES EMG activity also exceeded the body weight squat, deadlift, superman, and sidebridge exercises by 66.7, 65.5, 69.3, and 68.6%, respectively. There were no significant changes in EO or LA activity. Therefore, the augmented activity of the LSES and ULES during 80% 1RM squat and deadlift resistance exercises exceeded the activation levels achieved with the same exercises performed with body weight and selected instability exercises. Individuals performing upright, resisted, dynamic exercises can achieve high trunk muscle activation and thus may not need to add instability device exercises to augment core stability training.

Reliability and Measurement Error

Chapter

May 2020

Cardiovascular and subjective responses to one-and three-repetition maximum strength testing

Article

Jan 2002

Using the overhead squat for core development

Article

Jan 2004

I. Hasegawa

The basics of surface of electromyography

Article

Jan 1998

Mechanomyographic and electromyographic responses to repeated, concentric muscle actions

Conference Paper

May 2004

COMPARISON OF THE ACTIVITIES OF THE DEEP TRUNK MUSCLES MEASURED USING INTRAMUSCULAR AND SURFACE ELECTROMYOGRAPHY

Article

Apr 2012

Surface electromyography (EMG) has been used to estimate deep trunk muscle activity. However, it remains unknown whether surface EMG provides an accurate estimation of this activity. The purposes of this study were to compare surface and intramuscular EMG activity measurements and investigate the efficacy of surface EMG measurement for the transversus abdominis (TrA) and the multifidus (MF) muscles. Eight healthy men participated in the study. TrA and MF activities were simultaneously measured by both intramuscular and surface EMG during isometric trunk exercises. Spearman correlation coefficients for the relationship between the two activity measurements for the right TrA, left TrA, right MF, and left MF were 0.55, 0.36, 0.67, and 0.79, respectively. For the TrA, Bland–Altman plots revealed that mean differences between measurements obtained by intramuscular EMG and surface EMG were not close to zero, with a systematic bias toward higher surface EMG values. In conclusion, surface and intramuscular EMG activity measurements were strongly correlated for MF muscles, but poorly correlated for TrA muscles.

Mechanomyographic and Electromyographic Responses to Repeated, Concentric Muscle Actions

Article

May 2004

Kyle T Ebersole

CARDIOVASCULAR AND SUBJECTIVE RESPONSES TO ONE REPETITION (1RM) AND THREE REPETITION MAXIMUM (3RM) TESTING

Article

May 2001

Exercise techniques: The overhead squat

Article

Oct 1988
Natl Strength Condit Assoc J

Muscle Activation in the Loaded Free Barbell Squat

Article

Feb 2012
J STRENGTH COND RES

The purpose of this article was to review a series of studies (n = 18) where muscle activation in the free barbell back squat was measured and discussed. The loaded barbell squat is widely used and central to many strength training programs. It is a functional and safe exercise that is obviously transferable to many movements in sports and life. Hence, a large and growing body of research has been published on various aspects of the squat. Training studies have measured the impact of barbell squat loading schemes on selected training adaptations including maximal strength and power changes in the squat. Squat exercise training adaptations and their impact on a variety of performance parameters, in particular countermovement jump, acceleration, and running speed, have also been reported. Furthermore, studies have reported on the muscle activation of the lower limb resulting from variations of squat depth, foot placement, training status, and training intensity. There have also been studies on the impact of squatting with or without a weight belt on trunk muscle activation (TMA). More recently, studies have reported on the effect of instability on TMA and squat performance. Research has also shown that muscle activation of the prime movers in the squat exercise increases with an increase in the external load. Also common variations such as stance width, hip rotation, and front squat do not significantly affect muscle activation. However, despite many studies, this information has not been consolidated, resulting in a lack of consensus about how the information can be applied. Therefore, the purpose of this review was to examine studies that reported muscle activation measured by electromyography in the free barbell back squat with the goal of clarifying the understanding of how the exercise can be applied.

Comparison of Kinetic Variables and Muscle Activity During a Squat vs. a Box Squat

Article

Dec 2010
J STRENGTH COND RES

The purpose of this investigation was to determine if there was a difference in kinetic variables and muscle activity when comparing a squat to a box squat. A box squat removes the stretch-shortening cycle component from the squat, and thus, the possible influence of the box squat on concentric phase performance is of interest. Eight resistance trained men (Height: 179.61 ± 13.43 cm; Body Mass: 107.65 ± 29.79 kg; Age: 24.77 ± 3.22 years; 1 repetition maximum [1RM]: 200.11 ± 58.91 kg) performed 1 repetition of squats and box squats using 60, 70, and 80% of their 1RM in a randomized fashion. Subjects completed the movement while standing on a force plate and with 2 linear position transducers attached to the bar. Force and velocity were used to calculate power. Peak force and peak power were determined from the force-time and power-time curves during the concentric phase of the lift. Muscle activity (electromyography) was recorded from the vastus lateralis, vastus medialis, biceps femoris, and longissimus. Results indicate that peak force and peak power are similar between the squat and box squat. However, during the 70% of 1RM trials, the squat resulted in a significantly lower peak force in comparison to the box squat (squat = 3,269 ± 573 N, box squat = 3,364 ± 575 N). In addition, during the 80% of 1RM trials, the squat resulted in significantly lower peak power in comparison to the box squat (squat = 2,050 ± 486 W, box squat = 2,197 ± 544 W). Muscle activity was generally higher during the squat in comparison to the box squat. In conclusion, minimal differences were observed in kinetic variables and muscle activity between the squat and box squat. Removing the stretch-shortening cycle during the squat (using a box) appears to have limited negative consequences on performance.

The Lumbar and Sacrum Movement Pattern During the Back Squat Exercise

Article

Oct 2010
J STRENGTH COND RES

An essential exercise for strength training of the lower limbs is the squat exercise. During this exercise, changes in lumbar lordosis are commonly used to indicate when the descent of the squat should cease, yet the behavior of the lumbar-scarum segments remains unclear. The purpose of this study was to quantify the lumbar-sacrum movements during the back squat, because the movement of the sacrum is influenced by the width of stance, this variable was also investigated. Thirty trained subjects, 18 men with 1 repetition maximum (1RM) squat of 123% (13.9%) of bodyweight and 12 women with 1RM squat of 93% (15.6%), performed a set of narrow and wide stance squats, each carrying an additional 50% of body weight as load. The timing and movement of the lumbar angle (T12/L1), sacrum angle (L5/S1), and lumbar flexion angle (lumbar lordosis) were measured in 3 dimensions for the ascent and decent phases. Men and women achieved similar lumbar angles for both width of stance and phase. Sacrum angles, lumbar flexion angles, and timing differed significantly (p < 0.05) between gender and width of stance. The lumbar flexion range during the descent phase for women in narrow and wide stance was 12.9° and 12.6°, respectively; for men, this range was significantly (p < 0.05) larger at 26.3° and 25.4°, respectively. Men and women developed different movement patterns for the squatting movement, and therefore, this needs to be considered in strength development and screening procedures. The lumbar spine became kyphotic as soon as a load was placed on the shoulders, and any teaching cues to maintain a curved lumbar spine when squatting must be questioned.

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

Article

Jun 2010

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. 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 first 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 revealed a statistically significant difference between S1RM and U1RM values (P < or = .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. Unstable squatting is of equal or less (depending on the loading condition) benefit to improving or maximizing muscle activity during resistance exercise.

Trunk Muscle Activity During Lumbar Stabilization Exercises on Both a Stable and Unstable Surface

Article

Jun 2010

Controlled laboratory study. To clarify whether differences in surface stability influence trunk muscle activity. Lumbar stabilization exercises on unstable surfaces are performed widely. One perceived advantage in performing stabilization exercises on unstable surfaces is the potential for increased muscular demand. However, there is little evidence in the literature to help establish whether this assumption is correct. Nine healthy male subjects performed lumbar stabilization exercises. Pairs of intramuscular fine-wire or surface electrodes were used to record the electromyographic signal amplitude of the rectus abdominis, the external obliques, the transversus abdominis, the erector spinae, and lumbar multifidus. Five exercises were performed on the floor and on an unstable surface: elbow-toe, hand-knee, curl-up, side bridge, and back bridge. The EMG data were normalized as the percentage of the maximum voluntary contraction, and data between doing each exercise on the stable versus unstable surface were compared using a Wilcoxon signed-rank test. With the elbow-toe exercise, the activity level for all muscles was enhanced when performed on the unstable surface. When performing the hand-knee and side bridge exercises, activity level of the more global muscles was enhanced when performed on an unstable surface. Performing the curl-up exercise on an unstable surface, increased the activity of the external obliques but reduced transversus abdominis activation. This study indicates that lumbar stabilization exercises on an unstable surface enhanced the activities of trunk muscles, except for the back bridge exercise.

Muscle Activation Patterns While Lifting Stable and Unstable Loads on Stable and Unstable Surfaces

Article

Feb 2010
J STRENGTH COND RES

In an attempt to mimic everyday activities that are performed in 3-dimensional environments, exercise programs have been designed to integrate training of the trunk muscles with training of the extremities. Many believe that the most effective way to recruit the core stabilizing muscles is to execute traditional exercise movements on unstable surfaces. However, physical activity is rarely performed with a stable load on an unstable surface; usually, the surface is stable, and the external resistance is not. The purpose of this study was to evaluate muscle activity of the prime movers and core stabilizers while lifting stable and unstable loads on stable and unstable surfaces during the seated overhead shoulder press exercise. Thirty resistance-trained subjects performed the shoulder press exercise for 3 sets of 3 repetitions under 2 load (barbell and dumbbell) and 2 surface (exercise bench and Swiss ball) conditions at a 10 repetition maximum relative intensity. Surface electromyography (EMG) measured muscle activity for 8 muscles (anterior deltoid, middle deltoid, trapezius, triceps brachii, rectus abdominis, external obliques, and upper and lower erector spinae). The average root mean square of the EMG signal was calculated for each condition. The results showed that as the instability of the exercise condition increased, the external load decreased. Triceps activation increased with external resistance, where the barbell/bench condition had the greatest EMG activation and the dumbbell/Swiss ball condition had the least. The upper erector spinae had greater muscle activation when performing the barbell presses on the Swiss ball vs. the bench. The findings provide little support for training with a lighter load using unstable loads or unstable surfaces.

A Comparison of Free Weight Squat to Smith Machine Squat Using Electromyography

Article

Oct 2009
J STRENGTH COND RES

The purpose of this experiment was to determine whether free weight or Smith machine squats were optimal for activating the prime movers of the legs and the stabilizers of the legs and the trunk. Six healthy participants performed 1 set of 8 repetitions (using a weight they could lift 8 times, i.e., 8RM, or 8 repetition maximum) for each of the free weight squat and Smith machine squat in a randomized order with a minimum of 3 days between sessions, while electromyographic (EMG) activity of the tibialis anterior, gastrocnemius, vastus medialis, vastus lateralis, biceps femoris, lumbar erector spinae, and rectus abdominus were simultaneously measured. Electromyographic activity was significantly higher by 34, 26, and 49 in the gastrocnemius, biceps femoris, and vastus medialis, respectively, during the free weight squat compared to the Smith machine squat (p < 0.05). There were no significant differences between free weight and Smith machine squat for any of the other muscles; however, the EMG averaged over all muscles during the free weight squat was 43% higher when compared to the Smith machine squat (p < 0.05). The free weight squat may be more beneficial than the Smith machine squat for individuals who are looking to strengthen plantar flexors, knee flexors, and knee extensors.

The Effect of Stance Width on the Electromyographical Activity of Eight Superficial Thigh Muscles During Back Squat With Different Bar Loads

Article

Feb 2009
J STRENGTH COND RES

Many strength trainers believe that varying the stance width during the back squat can target specific muscles of the thigh. The aim of the present work was to test this theory measuring the activation of 8 thigh muscles while performing back squats at 3 stance widths and with 3 different bar loads. Six experienced lifters performed 3 sets of 10 repetitions of squats, each one with a different stance width, using 3 resistances: no load, 30% of 1-repetition maximum (1RM), and 70% 1RM. Sets were separated by 6 minutes of rest. Electromyographic (EMG) surface electrodes were placed on the vastus medialis, vastus lateralis, rectus femoris, semitendinosus, biceps femoris, gluteus maximus, gluteus medium, and adductor maior. Analysis of variance and Scheffè post hoc tests indicated a significant difference in EMG activity only for the gluteus maximus; in particular, there was a higher electrical activity of this muscle when back squats were performed at the maximum stance widths at 0 and 70% 1RM. There were no significant differences concerning the EMG activity of the other analyzed muscles. These findings suggest that a large width is necessary for a greater activation of the gluteus maximus during back squats.

Appropriately placed surface EMG electrodes reflect deep muscle activity (Psoas, Quadratus Lumborum, Abdominal Wall) in the lumbar spine

Article

Dec 1996
J BIOMECH

This study tested the possibility of obtaining the activity of deeper muscles in the torso—specifically psoas, quadratus lumborum, external oblique, internal oblique and transverse abdominis, using surfce myoelectric electrodes. It was hypothesized that: (1) surface electrodes adequately represent the amplitude of deep muscles (specifically psoas, quadratus lumborum, external oblique, internal oblique, transverse abdominis); (2) a single surface electrode location would best represent the activation profiles of each deep muscle over a broad variety of tasks. We assumed that prediction of activation within 10% of maximum voluntary contraction (RMS difference between the surface and intramuscular channels), over the time history of the signal, was reasonable and acceptable to assist clinical interpretation of muscle activation amplitude, and ultimately for modeled estimates of muscle force. Surface electrodes were applied and intramuscular electrodes were inserted on the left side of the body in five men and three women who then performed a wide variety of flexor tasks (bent knee and straight leg situps and leg raises, curl ups), extensor tasks (including lifting barbells up to 70 kg), lateral bending tasks (standing lateral bend and horizontal lying side support), twisting tasks (standing and sitting), and internal/external hip rotation. Using the criteria of RMS difference and the coefficient of determination (R²) to compare surface with intramuscular myoelectric signals, the results indicated that selected surface electrodes adequately represent the amplitude of deep muscles—always within 15% RMS difference, or less with the exception of psoas where differences up to 20% were observed but only in certain maximum voluntary contraction efforts.

The Effect of Back Squat Depth on the EMG Activity of 4 Superficial Hip and Thigh Muscles

Article

Aug 2002

The purpose of this study was to measure the relative contributions of 4 hip and thigh muscles while performing squats at 3 depths. Ten experienced lifters performed randomized trials of squats at partial, parallel, and full depths, using 100-125% of body weight as resistance. Electromyographic (EMG) surface electrodes were placed on the vastus medialis (VMO), the vastus lateralis, (VL), the biceps femoris (BF), and the gluteus maximus (GM). EMG data were quantified by integration and expressed as a percentage of the total electrical activity of the 4 muscles. Analysis of variance (ANOVA) and Tukey post hoc tests indicated a significant difference (p < 0.001*, p = 0.056**) in the relative contribution of the GM during the concentric phases among the partial- (16.9%*), parallel- (28.0%**), and full-depth (35.4%*) squats. There were no significant differences between the relative contributions of the BF, the VMO, and the VL at different squatting depths during this phase. The results suggest that the GM, rather than the BF, the VMO, or the VL, becomes more active in concentric contraction as squat depth increases.

Surface EMG electrodes do not accurately record lumbar multifidus muscle

Article

Feb 2003
CLIN BIOMECH

This study investigated whether electromyographic signals recorded from the skin surface overlying the multifidus muscles could be used to quantify their activity. Comparison of electromyography signals recorded from electrodes on the back surface and from wire electrodes within four different slips of multifidus muscles of three human subjects performing isometric tasks that loaded the trunk from three different directions. It has been suggested that suitably placed surface electrodes can be used to record activity in the deep multifidus muscles. We tested whether there was a stronger correlation and more consistent regression relationship between signals from electrodes overlying multifidus and longissimus muscles respectively than between signals from within multifidus and from the skin surface electrodes over multifidus. The findings provided consistent evidence that the surface electrodes placed over multifidus muscles were more sensitive to the adjacent longissimus muscles than to the underlying multifidus muscles. The R(2) for surface versus intra-muscular comparisons was 0.64, while the average R(2) for surface-multifidus versus surface-longissimus comparisons was 0.80. Also, the magnitude of the regression coefficients was less variable between different tasks for the longissimus versus surface multifidus comparisons. Accurate measurement of multifidus muscle activity requires intra-muscular electrodes. Electromyography is the accepted technique to document the level of muscular activation, but its specificity to particular muscles depends on correct electrode placement. For multifidus, intra-muscular electrodes are required.

Using surface electromyography

Article

Dec 2001

Glenn S Kasman

Influence of Different Relative Intensities on Power Output During the Hang Power Clean: Identification of the Optimal Load

Article

Sep 2005

The influence of different relative intensities on power output was investigated in the present study in order to identify the optimal load that maximizes power output during the hang power clean. Fifteen men (age: 22.1 +/- 2.0 years, height: 180.1 +/- 6.3 cm, and body mass: 89.4 +/- 14.7 kg) performed the hang power cleans on a forceplate at 30-90% of one repetition maximum (1RM). Peak power was maximized at 70% 1RM, which was, however, not significantly different from peak power at 50, 60, 80, and 90% 1RM. Average power also was maximized at 70% 1RM, which was not significantly different from average power at 40, 50, 60, 80, and 90% 1RM. It was concluded that (a) the relative intensity had a significant influence on power output, and (b) power output can be maximized at a submaximal load during the hang power clean.

Electromyographic and Kinetic Comparison of the Back Squat and Overhead Squat

Abstract

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