Quadriceps Muscle Activity During Exercise

 

Naresh Bhaskar Raj¹*, Nor Azizah Hussin¹, Nordin Bin Simbak²,

Mohd Khairuddin Mohd Safee¹, Mahadeva Rao US²

¹Faculty of Health Sciences, Universiti Sultan Zainal Abidin (UniSZA), 21300 Kuala Terengganu,

Terengganu Darul Iman, Malaysia

²Faculty of Medicine, Universiti Sultan Zainal Abidin (UniSZA), 20400 Kuala Terengganu,

Terengganu Darul Iman, Malaysia

 

ABSTRACT:

Various forms of exercises are imparted for patients with lower extremity problems. These exercises are helpful in strengthening the muscles of the lower limb mainly those of quadriceps and hamstring. This study was intended to investigate the activity of vastusmedialis oblique and vastuslateralis during selected exercises of Static Quadriceps Exercise (SQE), Inner Range Quadriceps exercise (IRQ), Straight Leg Raise (SLR), Active Knee Extension exercise (AKE) and semisquat. About 50 healthy individuals (15 Males and 35 Females) in the age group of 18 -24 years (Male= 21.2 ± 1.21, Female= 20.3 ± 0.8) were recruited for the study based on the inclusion criteria. Surface electromyographic electrodes were affixed to Vastusmedialis Oblique (VMO) and vastuslateralis (VL) muscle. Each subject was advised to perform all the five exercises, and the muscle activity during each exercise was recorded using MyotracInfiniti, and the data were analysed with the aid of Biograph Infiniti software. Descriptive and inferential statistics were performed using SPSS version 22.0. The findings of the research indicated that inner range quadriceps exercise was significantly better in facilitating VMO and VL with no significant difference between the two during various exercise. It was also observed that the VMO/VL ratio was similar in all the exercise indicating equal activation of both muscles.

 

 

 

INTRODUCTION:

Exercises have played an important part in the rehabilitation of the knee injuries and pathologies. Therapists mainly use static quadriceps exercise, straight leg raise, inner range quadriceps, active knee extension and semi squat in the rehabilitation of the orthopaedic crises. However not much is known about the muscular contraction and its intensity during these exercises. It was observed that quadriceps femoris muscle activity was highest during quadriceps setting exercises. ^[1] In another research; it was observed that the quadriceps femoris muscle activity was greater in isometric contractions than that of straight leg raises.

The muscles that were recorded during this research were that of rectus femoris, vastuslateralis and vastus medialis.^[2] Similarly Skurja et al., (1980) compared the activity of vastusmedialis oblique and rectus femoris muscle during isometric contractions and straight leg raises. They reported that the electrical activity of vasti muscles was greater during isometric contractions whereas in straight leg raises the electrical activity of rectus femoris was observed to be the greatest.^[3] Likewise, Soderberg and Cook also observed an increased rectus femoris activity during straight leg raises in their research in which they compared the electromyographic data of four muscles during quadriceps setting exercises and straight leg raising exercises.^[4] The integrated electromyographic ratios of vastusmedialis oblique and vastuslateralis were investigated by Souza and Gross in healthy subjects and also in patients with patellofemoral pain during isometric, concentric and eccentric exercises.^[5] The researchers reported that there were no significant differences in the ratio between the normal subjects and the clients with patellofemoral pain. But still it was observed that there were differences in the EMG activities of the muscles with different exercises. The activities of Vastus medialisoblique and vastus lateralis during hip adduction and medial rotation exercises were investigated by Hanton and Schulthies.^[6] The researchers reported that the electrical activity of vastus medialis was greater in hip adduction exercises compared to that of vastus lateralis but the ratio between them was not significantly different.

 

Kusion et al., 2012 investigated the activation of vastus medialisoblique and vastus lateralis during four rehabilitative exercises in 34 subjects aged between 22-28 years. ^[7] The researchers reported that short arc knee extensions exercises were observed to activate the vastus medialis oblique and vastus lateralis more than the straight leg raises. Continued research should be done to investigate the activity of the muscles in commonly used strengthening exercises of thigh to achieve high standards of care for subjects with orthopedic crises of the lower limb. The purpose of the study was to investigate the activity of vastus medialis and vastus lateralis during commonly used exercises such as static quadriceps exercise (SQE), inner range quadriceps exercise, straight leg raise, active knee extension and half squat. By investigating the activity of the muscle during various exercises, we hope to find out the exercise that can preferentially activate the vastus medialis and vastus lateralis muscle which could well be used in the rehabilitation of patients.

 

METHODS:

The study was a repeated measures design. Surface EMG was used to analyse the activation of vastus medialis and vastus lateralis muscle during different exercises. Fifty healthy students were recruited for this study. The medical histories of all subjects were reviewed, and subjects without any history of neurological or orthopaedic dysfunction, surgery or pain in the lower extremities, were selected. Before the collection of data, the subjects read and signed an informed consent form approved by the University Human Research Ethics (UHRECH) for participation in this study. The subjectsrandomised for different exercises using research randomizer software. Measurement of height, weight, body mass index were taken. The participants were given instructions and demonstration about the exercises to be performed and also about the EMG equipment.

 

EQUIPMENT:

MyotracInfiniti^TMT  9800 was used to measure and record the electrical activity of the muscle. The data was analysed using Bio Graphinfiniti software. Bipolar adhesive surface electrodes (Ag-AgCl) were used over the muscle bellies of the VMO and VL. A goniometer was used to measure joint angles during the study done. A measurement tape was used in identifying the area for electrode placement.

 

PROCEDURE:

Orientation session:

An orientation session was used to familiarize the subjects with the exercises to be performed. The subjects need to complete five exercises. They were static quadriceps exercise (SQE), inner range quadriceps (IRQ), straight leg raise (SLR), active knee extension and semi squat. The position of subjects during SQE, IRQ and SLR was in lying. While in lying position, to perform SQE, the subject was instructed to press the back of the knee as hard as possible into the couch. ^[8] For IRQ exercise, a small rolled towel was placed underneath their knee till reach 40˚ knee flexion which will be confirmed by using the goniometer. Then, the subject was instructed to extend the knee. ^[9] For SLR exercise, the untested leg was positioned in 90˚ knee flexion which was confirmed by the goniometer while the foot flat on plinth. A straight edge will be held perpendicular across the untested knee which acts as a guide for ROM. Then, with the tested leg in straight position, the subject was instructed to lift up the tested leg till reach the straight edge. There was no load attached to the leg to simulate an initial phase of a rehabilitation program.^[7] To perform active knee extension exercise, the subject was in high sitting on a couch and the heel of the tested leg were placed on the cones which reach 30˚ knee flexion. Then, the subject was instructed to extend the knee, heel off the cones. ^[10] In performing semi squat exercise, a glass panel was placed 15 cm in front of the body. Initially the subject was asked to stand in upright position. To guide the movement, the subject then was instructed to keep the upper arm elevated to 90 at the shoulder joint, just in front of the body, and use it as a single rigid-body (without moving the elbow, wrist, and hand). While maintaining their back in straight posture, they descend till the knee flexion 45˚ which was confirmed and controlled by goniometer. During squatting, the subjects were asked to keep the distance between the fingers on a frontal plane. ^[11]

 

Experimental Session:

The electromyography activity of VMO and VL were recorded activities during five exercises (SQE, IRQ, SLR, active knee extension exercise and semi squatting). We chose to test the right lower limb on all subjects to maintain consistency and to avoid moving the equipment. Each exercises was performed for 5 repetitions with a rest of 5 seconds between the repetition and a 5 second hold for each muscle contraction, while 3 minutes rest between each exercise to minimise fatigue.^[12]

 

Statistical Analysis:

The normalisation of data was investigated using Shapiro –Wilks Test. This analysis was done by using parametric tests. The differences between the vastus muscles were assessed using ANOVA with normalized RMS values, followed by Tukey’s test, when indicated. The data were analyzed using the Statistical Package for Social Sciences (SPSS) software (version 22.0). In all of the analyses, a significance level of p≤0.05 was used.

 

RESULTS:

The characteristics of the subjects are given in Table 1. The means and standard deviation of the electromyographic activity of vastus medialisobliqus and vastus lateralis are shown in Table 2.

 

Table 1: Subject Characteristics (Mean ± SD)

Gender	Age (Y)	Height (Cm)	Mass (Kg)	Body Mass Index	Percent Body Fat
Male	21.2 ± 1.21	166.71 ± 6.23	61.09 ± 8.86	21.9 ± 2.03	16.21 ± 4.0
Female	20.3 ± 0.8	155.2 ± 5.45	50.79 ± 6.21	21.03 ± 2.07	23.55 ± 2.26

 

Table 2: Means and Standard Deviations of EMG Activity of the VMO and VL in Selected Exercises

Exercises	VMO		VL
	Mean	SD	Mean	SD
SQE	70.58	43.37	76.78	35.61
IRQ	75.80	41.00	80.08	33.08
SLR	54.39	31.06	59.65	28.37
AKE	61.30	28.51	67.39	23.86
Semi squat	24.49	13.04	24.10	12.72

 

Analysis of the results shows that the mean value representing the electromyographic activity of vastus medialisoblique was high with the inner range quadriceps exercise followed by that of static quadriceps exercise. It was also observed that the active knee extension exercises also recorded high electrical activity of VMO followed by Straight leg raise exercise and the half squat or semi squat recorded the least activity of VMO. The same trend was observed in the EMG activity of vastuslateralis muscle with inner range quadriceps exercise recording high activity of vastus lateralis followed by SQE, AKE, SLR  and semi squat.

 

 

Graph 1: Means of EMG activity of the VMO in Selected Exercises (mV)

 

Graph 2: Means of EMG activity of the VL in Selected Exercises (mV)

 

 

Graph 3: Means of EMG activity of the VMO and VL in Selected Exercises (mV)

 

Table 3: Pairwise comparisons depicting the activity of VMO during various exercises

VMO		Mean Difference	Std. Error	Sig.b
SQE	IRQ	-5.22	3.76	1.00
	SLR	16.18*	4.55	.00
	AKE	9.27	5.31	.87
	SEMI-SQUAT	46.08*	5.47	.00
IRQ	SLR	21.40*	4.08	.00
	AKE	14.50*	4.38	.01
	SEMI-SQUAT	51.30*	5.19	.00
SLR	AKE	-6.90	4.26	1.00
	SEMI-SQUAT	29.89*	3.66	.00
AKE	SEMI-SQUAT	36.80*	3.50	.00

^*Significant at p<0.05

Results from ANOVA indicate that SQE was significantly better than straight leg raises and semi squat in activating the VMO (p<0.05). Similarly inner range quadriceps exercise were significantly better that SLR, AKE and semisquat in activating the VMO (p<0.05). The activity of VMO was significantly greater in straight leg raise than semi squat exercise (p<0.05). Likewise AKE was significantly better in activating vastus medialisobliqus compared with that of semisquat. Overall analysis reveals that vastua medialis activity was significantly more with inner range quadriceps exercise compared to other forms of exercises (Table 3).

 

Pairwise comparisons of the activity of vastus lateralis activity across various exercises evidentially indicates that SQE is significantly better in activating vastus lateralis compared to that of straight leg raise and semisquat (p<0.05). Vastus lateralis activity was significantly better in inner range quadriceps compared to that of other exercises. SLR was significantly better in activating the vastus lateralis compared with that of semisquat. Likewise active knee extension exercises were better in activating the vastus lateralis muscle compared with that of semi squat. Vastus lateralis activity was observed to be greater with inner range quadriceps exercise (p<0.05).

Table 4: Pairwise comparisons depicting the activity of VL during various exercises

VL		Mean Difference (I-J)	Std. Error	Sig.b
SQE	IRQ	-3.29	3.09	1.00
	SLR	17.13*	4.51	.00
	AKE	9.39	4.32	.34
	SEMISQUAT	52.68*	4.84	.00
IRQ	SLR	20.43*	4.52	.00
	AKE	12.69*	3.70	.01
	SEMISQUAT	55.97*	4.52	.00
SLR	AKE	-7.74	3.75	.44
	SEMISQUAT	35.54*	3.91	.00
AKE	SEMISQUAT	43.28*	3.44	.00

^*Significant at p<0.05

 

Table 5: Pairwise comparisons depicting the activity of VMO and VL during various exercises

 

 

Graph 4: VMO: VL ratio of various exercises

 

Results comparing the activity of vastus medialisoblique and vastus lateralis across different exercises shows that there were no significant difference between vastus medialisobliqus and vastus lateralis during all the exercises (p>0.05). It could also be seen that the VMO: VL ratio is almost 1, indicating the both muscles contracted in a synchronised manner.

 

DISCUSSION:

The main aim of this study was to investigate the electromyographic activity of vastus medialisobliqus and vastus lateralis during five exercises commonly used for rehabilitation of knee disorders. It was observed that inner range quadriceps exercise was better in activating the vastus medialisobliqus and vastus lateralis muscle compared to other exercises that were used in the study. It was also observed that static quadriceps exercise followed by straight leg raise, active knee extension and semi squat were effective in demonstrating the activity of the VMO and VL. When the activity of VMO and VL were compared with the exercises it was observed that there were no significant differences between the exercises. The VMO/VL ratio was also in the range of 0.90-1.01which indicated that there was equal activation of VMO and VL. This evidentially proved that there was simultaneous activity of VMO and VL during all these exercises. The activation of VMO and VL can be explained in terms of the anatomy and biomechanics of the muscles. The VMO and VL assist in the knee extension and this could explain the reason for greater activation of the VMO and VL due to the knee extension component at the end range.^[13]In static quadriceps exercise it was more of an isometric contraction and hence there was not much activity of the VMO and VL compared to that of the inner range quadriceps exercise.^[14]With straight leg raise, the VMO and VL function mainly as stabiliser of the knee joint when the rectus femoris flexes the hip joint and this in turn explains the reason behind the level of activation of VMO and VL with SLR. Another possibility is due to the decrease in the moment arm of the quadriceps during SLR. ^[15] In active knee extension exercise, the subject was in high sitting position and the subject performed extension of the knee joint from the baseline position of 30° knee flexion and this could possibly explain the reason why the activity of VMO and VL was less compared with that od inner range quadriceps exercise. In semi squat there could be a possible activation of the hamstring and quadriceps muscle as a whole rather than increased activity of selected muscles among quadriceps and Hamstrings and this needs further investigation. The VMO/VL ratio of our study is similar to that of Kushion et al., (2012).^[7] This was in contrast to the findings of Tang et al., (2001) in which the researchers reported an increases activation of VMO and VL with semi squat in subjects with patellofemoral pain syndrome.^[16] With regard to VMO/VL ration during semi squat our finding is similar to that of Koh, Lee and Jung.^[17] The researchers reported a high VMO/VL which is in line with our finding of VMO/VL ratio. The five exercises used in the study are commonly used in the rehabilitation of orthopaedic disorders. ^[18] Most of the researchers have assessed the activity of VMO and VL on patients with patellofemoral pain syndrome whereas our study was performed on healthy individuals.

 

LIMITATIONS:

There were few limitations in our study such as, recruitment of healthy individuals, measurement of the activity of VMO and VL only, five exercises only were included and possibility of gender differences in research. All these limitation should be taken into consideration in further studies.

 

CONCLUSION:

The findings of the study conclude that inner range quadriceps exercise was significantly better in activating the vastus medialis oblique and vastus lateralis when compared with static quadriceps exercise, straight leg raise, active knee extension exercise and semi squat. There were no significant differences in VMO and VL amongst the exercise groups. The VMO/VL ratio was similar amongst the exercise indicating that there was equal activation VMO and VL and a highest VMO/VL ratio was observed in semi squat.

 

ACKNOWLEDGEMENT:

The present research is supported by the University research grant (DPU) (UNISZA/2015/DPU/48). The researchers of the current study are indebted to the authorities for awarding us with the grant necessary to carry out the study.

 

CONFLICT OF INTEREST:

Declared None.

 

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Accepted on 13.10.2017        © RJPT All right reserved

Research J. Pharm. and Tech 2017; 10(10):3312-3316.