Influence of the Amount of Instability on the Leg Muscle Activity During a Loaded Free Barbell Half-Squat

This study aimed to understand the acute responses on the muscular activity of primary movers during the execution of a half-squat under different unstable devices. Fourteen male and female high-standard track and field athletes were voluntarily recruited. A repeated measures design was used to establish the differences between muscle activity of the primary movers, the body centre of mass acceleration and the OMNI-Perceived Exertion Scale for Resistance Exercise (OMNI-Res) in a half-squat under four different stability conditions (floor, foam, BOSU-up and BOSU-down). A significant correlation was found between the highest performance limb muscle activity and body centre of mass acceleration for half-squat floor (r = 0.446, p = 0.003), foam (r = 0.322, p = 0.038), BOSU-up (r = 0.500, p = 0.001), and BOSU-down (r = 0.495, p = 0.001) exercises. For the exercise condition, the half-squat BOSU-up and BOSU-down significantly increased the muscle activity compared to half-squat floor (vastus medialis: p = 0.020, d = 0.56; vastus lateralis: p = 0.006, d = 0.75; biceps femoris: p = 0.000–0.006, d = 1.23–1.00) and half-squat foam (vastus medialis: p = 0.005–0.006, d = 0.60–1.00; vastus lateralis: p = 0.014, d = 0.67; biceps femoris: p = 0.002, d = 1.00) activities. This study contributes to improving the understanding of instability training, providing data about the acute muscular responses that an athlete experiences under varied stability conditions. The perturbation offered by the two BOSU conditions was revealed as the most demanding for the sample of athletes, followed by foam and floor executions.

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Single-Leg Squat Delicacies—The Position of the Nonstance Limb is an Important Consideration

Journal of Sport Rehabilitation ◽

10.1123/jsr.2018-0181 ◽

2019 ◽

Vol 28 (4) ◽

pp. 318-324

Author(s):

Benita Olivier ◽

Samantha-Lynn Quinn ◽

Natalie Benjamin ◽

Andrew Craig Green ◽

Jessica Chiu ◽

...

Keyword(s):

Muscle Activity ◽

Repeated Measures ◽

Inertial Sensors ◽

Center Of Mass ◽

Rectus Femoris ◽

Biceps Femoris ◽

Trunk Flexion ◽

Repeated Measures Design ◽

Mass Displacement ◽

Single Leg Squat

Context: The single-leg squat task is often used as a rehabilitative exercise or as a screening tool for the functional movement of the lower limb. Objective: To establish the effect of 3 different positions of the nonstance leg on 3-dimensional kinematics, muscle activity, and center of mass displacement during a single-leg squat. Design: Within-subjects, repeated-measures design. Setting: Movement analysis laboratory. Participants: A total of 10 participants, aged 28.2 (4.42) years performed 3 squats to 60° of knee flexion with the nonstance (1) hip at 90° flexion and knee at 90° flexion, (2) hip at 30° flexion with the knee fully extended, or (3) hip in neutral/0° and the knee flexed to 90°. Main Outcome Measures: Trunk, hip, knee and ankle joint angles, and center of mass displacement were recorded with inertial sensors while muscle activity was captured through wireless electromyography. Results: Most trunk flexion (21.38° [18.43°]) occurred with the nonstance hip at 90° and most flexion of the stance hip (23.10° [6.60°]) occurred with the nonstance hip at 0°. Biceps femoris activity in the 90° squat was 40% more than in the 0° squat, whereas rectus femoris activity in the 0° squat was 29% more than in the 90° squat. Conclusion: The position of the nonstance limb should be standardized when the single-leg squat is used for assessment and be adapted to the aim when used in rehabilitation.

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Lack of Effect of Ankle Position During the Nordic Curl on Muscle Activity of the Biceps Femoris and Medial Gastrocnemius

Journal of Sport Rehabilitation ◽

10.1123/jsr.2015-0130 ◽

2017 ◽

Vol 26 (3) ◽

pp. 202-207 ◽

Cited By ~ 1

Author(s):

Paul Comfort ◽

Amy Regan ◽

Lee Herrington ◽

Chris Thomas ◽

John McMahon ◽

...

Keyword(s):

Muscle Activity ◽

Repeated Measures ◽

Biceps Femoris ◽

Medial Gastrocnemius ◽

Maximum Voluntary Isometric Contraction ◽

Hamstring Strain ◽

Repeated Measures Design ◽

Paired Samples ◽

Significant Difference ◽

Male College

Context:Regular performance (~2×/wk) of Nordic curls has been shown to increase hamstring strength and reduce the risk of hamstring strain injury, although no consensus on ankle position has been provided.Objective:To compare the effects of performing Nordic curls, with the ankle in a dorsiflexed (DF) or plantar-flexed (PF) position, on muscle activity of the biceps femoris (BF) and medial gastrocnemius (MG).Participants:15 male college athletes (age 22.6 ± 2.1 y, height 1.78 ± 0.06 m, body mass 88.75 ± 8.95 kg).Design:A repeated-measures design was used, with participants performing 2 sets of 3 repetitions of both variations of Nordic curls, while muscle activity was assessed via surface electromyography (EMG) of the BF and MG. Comparisons of muscle activity were made by examining the normalized EMG data as the percentage of their maximum voluntary isometric contraction.Results:Paired-samples t test revealed no significant difference in normalized muscle activity of the BF (124.5% ± 6.2% vs 128.1 ± 5.0%, P > .05, Cohen d = 0.64, power = .996) or MG (82.1% ± 3.9% vs 83.5 ± 4.8%, P > .05, Cohen d = 0.32, power = .947) during the Nordic curls in a PF or DF position, respectively.Conclusion:Ankle position does not influence muscle activity during the Nordic curl; however, performance of Nordic curls with the ankle in a DF position may be preferential, as this replicates the ankle position during terminal leg swing during running, which tends to be the point at which hamstring strains have been reported.

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Differences of Thigh Muscle Activation During Various Squat Exercise on Stable and Unstable Surfaces

Exercise Science ◽

10.15857/ksep.2021.30.3.387 ◽

2021 ◽

Vol 30 (3) ◽

pp. 387-395

Author(s):

Soojin Kim ◽

Joo-Hyun Lee ◽

Jihye Heo ◽

Eunwook Chang

Keyword(s):

Muscle Activity ◽

Repeated Measures ◽

Muscle Activation ◽

Vastus Lateralis ◽

Rectus Femoris ◽

Biceps Femoris ◽

Quadriceps Muscle ◽

Thigh Muscle ◽

Unstable Surface ◽

Co Activation

PURPOSE: The purpose of this study was to compare thigh muscle activities and muscle co-activation when performing squats, wall squats, and Spanish squats on stable and unstable ground.METHODS: Twenty-two healthy male subjects (age: 22.50±2.70 years, height: 178.72±6.04 cm, mass: 76.50±6.80 kg, body mass index: 24.00±2.10 kg/m2, and Godin activity questionnaire: 56.30±24.10) voluntarily participated in the study. All of the participants performed three different squat exercises on the floor and the BOSU ball with an electromyograph attached to each participant’s quadriceps (rectus femoris, RF; vastus lateralis, VL; and vastus medialis, VM) and hamstrings (biceps femoris, BF; semitendinosus, ST; and semimembranosus, SM). Repeated measures of analysis of variance were utilized to compare muscle activity during the three squats exercises by floor type.RESULTS: RF (p<.001, η2=.689), VL (p<.001, η2=.622), and VM (p=.002, η2=.375) showed significant differences between exercises. Spanish squats yielded greater BF activity than did wall squats (p=.018, η2=.269). ST yielded greater muscle activity with the BOSU ball than on the floor (p=.018, η2=.269). Finally, there was a significant ground exercise interaction effect on the co-activation, showing greater muscle co-activation with Spanish squats on the BOSU ball compared to squats, squats on the BOSU ball, and wall squat on the BOSU ball.CONCLUSIONS: The findings of this study indicate that Spanish squats could be an effective exercise option for the facilitation of RF, VL, VM, and BF muscle activation. In particular, performing Spanish squats on an unstable surface could be useful for patients who need to improve their quadriceps muscle activation.

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Fatigue and the Electromechanical Efficiency of the Vastus Medialis and Vastus Lateralis Muscles

Journal of Athletic Training ◽

10.4085/1062-6050-43.2.152 ◽

2008 ◽

Vol 43 (2) ◽

pp. 152-156 ◽

Cited By ~ 18

Author(s):

Kyle T. Ebersole ◽

David M. Malek

Keyword(s):

Repeated Measures ◽

Vastus Lateralis ◽

Knee Injuries ◽

Surface Emg ◽

Vastus Lateralis Muscle ◽

Vastus Medialis ◽

Mechanical Responses ◽

Repeated Measures Design ◽

Emg Amplitude ◽

History Of

Abstract Context: The relationship between the amplitudes of the mechanomyographic (MMG) and electromyographic (EMG) signals has been used to examine the “electromechanical efficiency” (EME) of normal and diseased muscle. The EME may help us to better understand the neuromuscular relationship between the vastus medialis and vastus lateralis muscles. Objective: To examine the EME of the vastus medialis and vastus lateralis muscles during a fatiguing task. Design: Repeated-measures design. Setting: Research laboratory. Patients or Other Participants: Ten healthy males (age = 23.2 ± 1.2 years) with no history of knee injury. Intervention(s): Seventy-five consecutive, maximal concentric isokinetic leg extensions at a velocity of 180°/s. Main Outcomes Measure(s): Bipolar surface EMG electrodes were placed over the vastus medialis and vastus lateralis muscles, with an MMG contact sensor placed adjacent to the superior EMG electrode on each muscle. The MMG and EMG amplitude values (root mean squares) were calculated for each of the 75 repetitions and normalized to the highest value from the 75 repetitions. The EME was expressed as the ratio of the log-transformed normalized MMG amplitude to the normalized EMG amplitude. For each muscle, the linear relationship for the normalized-group mean EME was determined across the 75 repetitions. Results: Linear regression indicated decreases in torque (R2 = .96), vastus medialis EME (R2 = .73), and vastus lateralis EME (R2 = .73). The slopes for the vastus medialis and vastus lateralis EME were not different (P > .10). Conclusions: The similarities in the fatigue-induced decreases in EME for the vastus medialis and vastus lateralis muscles suggested that symmetry was present between the muscles in the electric and mechanical responses to repeated, maximal muscle actions. The EME measurements may provide a unique insight into the influence of fatigue on the contractile properties of skeletal muscle, including alterations that occur to the intrinsic electric and mechanical components. The EME may be useful in assessing and quantifying clinically relevant asymmetries in vastus medialis and vastus lateralis muscle function in those with knee injuries.

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The Piezo-resistive MC Sensor is a Fast and Accurate Sensor for the Measurement of Mechanical Muscle Activity

Sensors ◽

10.3390/s19092108 ◽

2019 ◽

Vol 19 (9) ◽

pp. 2108 ◽

Cited By ~ 2

Author(s):

Andrej Meglič ◽

Mojca Uršič ◽

Aleš Škorjanc ◽

Srđan Đorđević ◽

Gregor Belušič

Keyword(s):

Muscle Activity ◽

Skeletal Muscles ◽

Time Course ◽

Vastus Lateralis ◽

Initial Pressure ◽

Rectus Femoris ◽

Signal Amplitude ◽

Biceps Femoris ◽

Erector Spinae ◽

Vastus Medialis

A piezo-resistive muscle contraction (MC) sensor was used to assess the contractile properties of seven human skeletal muscles (vastus medialis, rectus femoris, vastus lateralis, gastrocnemius medialis, biceps femoris, erector spinae) during electrically stimulated isometric contraction. The sensor was affixed to the skin directly above the muscle centre. The length of the adjustable sensor tip (3, 4.5 and 6 mm) determined the depth of the tip in the tissue and thus the initial pressure on the skin, fatty and muscle tissue. The depth of the tip increased the signal amplitude and slightly sped up the time course of the signal by shortening the delay time. The MC sensor readings were compared to tensiomyographic (TMG) measurements. The signals obtained by MC only partially matched the TMG measurements, largely due to the faster response time of the MC sensor.

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Optimizing athlete assessment of maximal force and rate of development: A comparison of the isometric squat and mid-thigh pull

10.1101/2020.04.17.046359 ◽

2020 ◽

Author(s):

Joao Renato Silva ◽

Vasileios Sideris ◽

Bryna C.R. Chrismas ◽

Paul J. Read

Keyword(s):

Muscle Activity ◽

Vastus Lateralis ◽

Gluteus Maximus ◽

Biceps Femoris ◽

Peak Force ◽

Erector Spinae ◽

Vastus Medialis ◽

Rate Of Development ◽

Hamstring Muscles ◽

Force Time

ABSTRACTThis study compared force-time characteristics and muscle activity between the isometric squat (ISQ) and mid-thigh pull (IMTP) in both bilateral (ISQBI and IMTPBI) and unilateral (ISQUNI and IMTPUNI) stance. Peak force (PF), rate-of-force (RFD) (e.g. 0-300ms) and EMG of the multifidus, erector spinae (ES), gluteus maximus (GM), biceps femoris (BF), semitendinosus (ST), vastus medialis (VM), vastus lateralis (VL) and soleus were recorded in ten recreationally trained males. PF was significantly greater during the ISQBI vs. IMTPBI (p=0.016, ES=1.08) but not in the unilateral test mode although effects remained moderate (ES=0.62). A trend indicated heightened RFD300ms (p = 0.083; ES=0.81) during the IMTPBI vs. the ISQBI, but these effects were smaller in the unilateral test (ES = 0.51). Greater (p<0.0001) EMG for VL (ES=1.00-1.13) and VM were recorded during the ISQ compared to IMTP modes in both modes (ES = 0.97 – 1.18). Greater BF EMG (p = 0.030, ES = 0.31) was shown in IMTPBI vs. ISQBI and these effects were stronger in the unilateral modes (p = < 0.05; ES = 0.81 – 0.83). Significantly greater ST activation was shown in both IMTPUNI (p < 0.05; ES = 0.69-0.76) and IMTPBI (p < 0.001; ES = 1.08). These findings indicate that ISQ results in elevated PF, whereas, RFD is heightened during the IMTP and these differences are more pronounced in bilateral modes. Greater activation of the quadriceps and hamstring muscles are expected in ISQ and IMPT respectively.

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Lower-Extremity Muscle Activity During Aquatic and Land Treadmill Running at the Same Speeds

Journal of Sport Rehabilitation ◽

10.1123/jsr.2013-0003 ◽

2014 ◽

Vol 23 (2) ◽

pp. 107-122 ◽

Cited By ~ 5

Author(s):

W. Matthew Silvers ◽

Eadric Bressel ◽

D. Clark Dickin ◽

Garry Killgore ◽

Dennis G. Dolny

Keyword(s):

Lower Extremity ◽

Outcome Measures ◽

Muscle Activity ◽

Tibialis Anterior ◽

Rectus Femoris ◽

Biceps Femoris ◽

Swing Phase ◽

Treadmill Running ◽

Vastus Medialis ◽

Lower Extremity Muscle

Context:Muscle activation during aquatic treadmill (ATM) running has not been examined, despite similar investigations for other modes of aquatic locomotion and increased interest in ATM running.Objectives:The objectives of this study were to compare normalized (percentage of maximal voluntary contraction; %MVC), absolute duration (aDUR), and total (tACT) lower-extremity muscle activity during land treadmill (TM) and ATM running at the same speeds.Design:Exploratory, quasi-experimental, crossover design.Setting:Athletic training facility.Participants:12 healthy recreational runners (age = 25.8 ± 5 y, height = 178.4 ± 8.2 cm, mass = 71.5 ± 11.5 kg, running experience = 8.2 ± 5.3 y) volunteered for participation.Intervention:All participants performed TM and ATM running at 174.4, 201.2, and 228.0 m/min while surface electromyographic data were collected from the vastus medialis, rectus femoris, gastrocnemius, tibialis anterior, and biceps femoris.Main Outcome Measures:For each muscle, a 2 × 3 repeated-measures ANOVA was used to analyze the main effects and environment–speed interaction (P ≤ .05) of each dependent variable: %MVC, aDUR, and tACT.Results:Compared with TM, ATM elicited significantly reduced %MVC (−44.0%) but increased aDUR (+213.1%) and tACT (+41.9%) in the vastus medialis, increased %MVC (+48.7%) and aDUR (+128.1%) in the rectus femoris during swing phase, reduced %MVC (−26.9%) and tACT (−40.1%) in the gastrocnemius, increased aDUR (+33.1%) and tACT (+35.7%) in the tibialis anterior, and increased aDUR (+41.3%) and tACT (+29.2%) in the biceps femoris. At faster running speeds, there were significant increases in tibialis anterior %MVC (+8.6−15.2%) and tACT (+12.7−17.0%) and rectus femoris %MVC (12.1−26.6%; swing phase).Conclusion:No significant environment–speed interaction effects suggested that observed muscle-activity differences between ATM and TM were due to environmental variation, ie, buoyancy (presumed to decrease %MVC) and drag forces (presumed to increase aDUR and tACT) in the water.

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Reciprocal Coactivation Patterns of the Lateral and Medial Quadriceps and Hamstrings during Low- and Moderate-Speed Isokinetic Movement

Journal of Sport Rehabilitation ◽

10.1123/jsr.7.3.182 ◽

1998 ◽

Vol 7 (3) ◽

pp. 182-196 ◽

Cited By ~ 3

Author(s):

Ronald V. Croce ◽

John P. Miller ◽

Robert Confessore ◽

James C. Vailas

Keyword(s):

Knee Joint ◽

Female Athletes ◽

Vastus Lateralis ◽

Biceps Femoris ◽

Median Frequency ◽

Vastus Medialis ◽

Mean Square ◽

Joint Movement ◽

Surface Electrodes ◽

Emg Patterns

The purpose of this study was to examine coactivation patterns of the lateral and medial quadriceps and the lateral and medial hamstrings during low- and moderate-speed isokinetic movements. Twelve female athletes performed isokinetic knee assessments at 60 and 180°/s. Root mean square electromyographic (rmsEMG) activity and the median frequency of the EMG (mfEMG) were determined by placing bipolar surface electrodes on the vastus lateralis (VL), vastus medialis (VM), biceps femoris (BF), and medial hamstrings (MH). Results of rmsEMG indicated that the VM showed almost twice the coactivation of the VL (p< .05), and that the BF showed almost four times the coactivation of the MH (p <.05). Finally, differences were noted in the mfEMG (p< .05), with the VM displaying different recruitment patterns at 180°/s as an agonist compared to that as an antagonist. Results indicated that when acting as antagonists, the VM and BE display the greatest EMG patterns during isokinetic knee joint movement.

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Development of an On-Water Graded Exercise Test for Flat-Water Sprint Kayak Athletes

International Journal of Sports Physiology and Performance ◽

10.1123/ijspp.2018-0717 ◽

2019 ◽

Vol 14 (9) ◽

pp. 1244-1249 ◽

Cited By ~ 2

Author(s):

Chelsie E. Winchcombe ◽

Martyn J. Binnie ◽

Matthew M. Doyle ◽

Cruz Hogan ◽

Peter Peeling

Keyword(s):

Oxygen Consumption ◽

Exercise Test ◽

Repeated Measures ◽

Perceived Exertion ◽

Intraclass Correlation ◽

Rating Of Perceived Exertion ◽

Stroke Rate ◽

Repeated Measures Design ◽

Graded Exercise Test ◽

Graded Exercise

Purpose: To determine the reliability and validity of a power-prescribed on-water (OW) graded exercise test (GXT) for flat-water sprint kayak athletes. Methods: Nine well-trained sprint kayak athletes performed 3 GXTs in a repeated-measures design. The initial GXT was performed on a stationary kayak ergometer in the laboratory (LAB). The subsequent 2 GXTs were performed OW (OW1 and OW2) in an individual kayak. Power output (PWR), stroke rate, blood lactate, heart rate, oxygen consumption, and rating of perceived exertion were measured throughout each test. Results: Both PWR and oxygen consumption showed excellent test–retest reliability between OW1 and OW2 for all 7 stages (intraclass correlation coefficient > .90). The mean results from the 2 OW GXTs (OWAVE) were then compared with LAB, and no differences in oxygen consumption across stages were evident (P ≥ .159). PWR was higher for OWAVE than for LAB in all stages (P ≤ .021) except stage 7 (P = .070). Conversely, stroke rate was lower for OWAVE than for LAB in all stages (P < .010) except stage 2 (P = .120). Conclusions: The OW GXT appears to be a reliable test in well-trained sprint kayak athletes. Given the differences in PWR and stroke rate between the LAB and OW tests, an OW GXT may provide more specific outcomes for OW training.

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Carbohydrate-Induced Insulin Signaling Activates Focal Adhesion Kinase: A Nutrient and Mechanotransduction Crossroads

Nutrients ◽

10.3390/nu12103145 ◽

2020 ◽

Vol 12 (10) ◽

pp. 3145 ◽

Cited By ~ 1

Author(s):

Dylan T. Wilburn ◽

Steven B. Machek ◽

Thomas D. Cardaci ◽

Darryn S. Willoughby

Keyword(s):

Focal Adhesion Kinase ◽

Focal Adhesion ◽

Insulin Signaling ◽

Repeated Measures ◽

Vastus Lateralis ◽

Future Research ◽

Placebo Condition ◽

Carbohydrate Ingestion ◽

Post Exercise ◽

Repeated Measures Design

Research has suggested that nutrient, exercise, and metabolism-related proteins interact to regulate mammalian target of rapamycin complex one (mTOR) post-exercise and their interactions needs clarification. In a double-blind, cross-over, repeated measures design, ten participants completed four sets to failure at 70% of 1-repitition maximum (1-RM) with 45 s rest on angled leg press with or without pre-exercise maltodextrin (2 g/kg) after a 3 h fast. Vastus lateralis biopsies were collected at baseline before supplementation and 1 h post-exercise to analyze Focal Adhesion Kinase (FAK), ribosomal protein S6 kinase beta-1 (p70S6K), insulin receptor substrate 1 (IRS-1), phosphatidylinositol 3-kinase (PI3K), and 5′ AMP-activated protein kinase (AMPK) activation. FAK and IRS-1 activity were only elevated 1 h post-exercise with carbohydrate ingestion (p < 0.05). PI3K and p70S6K activation were both elevated after exercise in both conditions (p < 0.05). However, AMPK activity did not change from baseline in both conditions (p > 0.05). We conclude that FAK does not induce mTOR activation through PI3K crosstalk in response to exercise alone. In addition, FAK may not be regulated by AMPK catalytic activity, but this needs further research. Interestingly, carbohydrate-induced insulin signaling appears to activate FAK at the level of IRS-1 but did not enhance mTOR activity 1 h post-exercise greater than the placebo condition. Future research should investigate these interactions under different conditions and within different time frames to clearly understand the interactions between these signaling molecules.

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