Search

BIO DESIGN

pISSN 2288-6982
eISSN 2288-7105

Article

Article

Original Article

Phys. Ther. Korea 2021; 28(4): 273-279

Published online November 20, 2021

https://doi.org/10.12674/ptk.2021.28.4.273

© Korean Research Society of Physical Therapy

Effect of Backward Versus Forward Lunge Exercises on Trunk Muscle Activities in Healthy Participants

Jae-Keun Song1 , PT, MSc, Won-Gyu Yoo2 , PT, PhD

1Department of Physical Therapy, The Graduate School, 2Department of Physical Therapy, College of Biomedical Science and Engineering, Inje University, Gimhae, Korea

Correspondence to: Won-Gyu Yoo
E-mail: won7y@inje.ac.kr
https://orcid.org/0000-0001-6200-9674

Received: November 9, 2021; Revised: November 12, 2021; Accepted: November 12, 2021

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Background: Lunge exercises are lower extremity rehabilitation and strengthening exercises for patients and athletes. Most studies have shown the effectiveness of the forward and backward lunge exercises for treating patellofemoral pain and anterior cruciate ligament injuries (by increasing lower extremity muscle activity) and improving kinematics.
Objects: However, it is not known how the two different lunge movements affect trunk muscle activities in healthy individuals. The purpose of this study was to investigate the electromyographic activity of the rectus abdominis and erector spinae muscles during forward and backward lunge exercises in healthy participants.
Methods: Twelve healthy participants were recruited. Electromyographic activity of the rectus abdominis and erector spinae was recorded using surface electrodes during forward and backward lunges, and subsequently normalized to the respective reference voluntary isometric contractions of each muscle.
Results: Activity of the erector spinae was significantly higher than that of the rectus abdominis during all stages of the backward lunge (p < 0.05). The activity of the erector spinae was significantly greater during the backward than forward lunge at all stages (p < 0.05).
Conclusion: Backward lunging is better able to enhance trunk motor control and activate the erector spinae muscles.

Keywords: Electromyography, Exercise, Rectus abdominis, Visual feedback

The lunge exercise is a motion in which one foot steps forward and the knee is bent to about 90°. Lunge exercises can be performed in a variety of ways by stepping in different directions. Lunge exercises include the forward, backward, side, and walking lunges [1]. These exercises are well-known among the general public and athletes, and can easily be performed in the gym or at home to effectively train muscles, such as the quadriceps and gluteus maximus [2-6]. Among lunge exercises, the forward lunge is often used for training and rehabilitation of athletes without any special equipment. The stepping forward movement and flexing of the stance leg are very intense exercise components that contribute to muscle strengthening by providing eccentric force stimulation, particularly to the hamstring muscle group behind the thigh [7-9]. In addition, the lunge exercise is recommended for initial rehabilitation and prevention of patellofemoral pain (PFP) syndrome and anterior cruciate ligament (ACL) injury [10-12]. The lunge exercise selectively strengthens the lower extremities, restores normal joint range of motion, and reduces displacement of the tibia. The weight load of closed chain motion exerts a compressive load on the joint surface, reducing anterior-posterior displacement of the tibia against the femur [12]. The forward lunge is effective for treating PFP. The lunging leg movement stimulates and strengthens the quadriceps and glutes, thereby increasing joint stability [13,14]. Moreover, the backward lunge, in which the foot steps backward and the knee is bent, is also effective for PFP. Park et al. [1] reported that the backward lunge reduces the shear force on the knee compared to the forward lunge, and decreases compression under the patella. Goulette et al. [15] reported that the backward lunge is a therapeutic exercise that should be considered for PFP, because the compression force on the patella-femoral joint is lower compared to the forward lunge. Additionally, lunge exercises not only affect the lower extremities but also stimulate the trunk and core muscles [1,12]. Coordination of the trunk and core muscles is required to maintain balance, because the lunge exercise requires single-limb balance of the stepping foot, which modulates the ascending and descending movements of the body [16,17]. The rectus abdominis and erector spinae, which comprise the trunk muscles, contribute to core stability and postural control of the trunk during sports activities. These two muscles facilitate normal gait by creating and regulating movements between the trunk and pelvis [18,19]. Training the trunk muscles improves the alignment of the lower extremities, thus improving landing of the foot and reducing the risk of an ACL injury by reducing the valgus force of the knee [12,20-23]. One study reported that activities of the trunk and core muscles contribute directly or indirectly to knee joint alignment, stability, and mobility, in addition to hamstring and quadriceps rehabilitation exercises for the ACL, including the lunge [12]. As reported in previous studies, the activities of the trunk muscles are very important when performing the lunge. However, most studies have reported the effect of lunging on the lower extremities; no study compared trunk muscle activation between the forward and backward lunge. Thus, it is not known how the two different lunge movements affect trunk muscle activities in healthy individuals. Therefore, the purpose of this study was to compare the activities of the rectus abdominis and erector spinae muscles during the forward and backward lunge in healthy participants. We hypothesized that the backward lunge would result in higher activity of the trunk muscles than the forward lunge due to lack of visul feedback.

1. Participants

The study subjects were 12 participants working at Mackenzie Ilsin Christian Hospital in Busan (Table 1). The experimental method and procedure were explained to all subjects who participated in this study after they signed the consent form. The criteria for selecting subjects were no damage to the nervous system or musculoskeletal system related to the trunk and lower extremities. Individuals with lower extremity pain were excluded, along with those who underwent lower extremity surgery within 12 months or had sustained trauma to their knees or ankles within the last 6 months.

Table 1 . Characteristics of subjects (N = 12).

SexAgeHeight (cm)Weight (kg)
Male (n = 6)28.0 ± 1.7178.2 ± 3.877.2 ± 6.4
Female (n = 6)26.2 ± 3.7162.2 ± 2.752.4 ± 2.5

Values are presented as mean ± standard deviation..



2. Instruments

1) Relive 4D-MT 2 channel wireless surface electromyograph

In this study, electromyography (EMG) was used to measure the activities of the rectus abdominis and erector spinae muscles during forward and backward lunging. EMG signals are produced by physiological changes occurring in the muscle tissue membrane. Measurements from each muscle were collected and processed using the 2EM instrument (4D-MT; Relive, Gimhae, Korea) (Figure 1). The sampling rate of the EMG signal was set to 1,000 Hz, and the frequency bandwidth was 0–500 Hz. By using the 2EM instrument, EMG value of the muscles was analyzed after determining the root mean square (RMS).

Figure 1. (A) 2EM (Electromyography [EMG] sensors). (B) Relive 4D-MT (EMG analysis program).
2) Tempo Lite metronome

This study used the Tempo Lite metronome (Frozen Ape Pte. Ltd., Singapore, Singapore) application to accurately measure and standardize the time when the subject performs the forward and backward lunges, to measure activities of the rectus abdominis and erector spinae muscles. The metronome application flashes to signal the beats per minute (bpm) and generates a constant rhythmic sound, allowing the subject to perform actions in time to the beat. When each subject performed the forward and backward lunges, the metronome setting was 60 bpm to generate a sound every second.

3. Procedure

The subjects warmed up for 5 minutes by performing simple lower extremity stretching exercises. Participants kicked a ball to identify the dominant leg. Then, forward and backward lunges were performed randomly by stepping the dominant foot forward or the non-dominant foot backward, with the feet shoulder-width apart (Figure 2). During the lunge, as a reference standard, the step length was marked with tape on the floor at a point corresponding to 75% of the length of the dominant leg. A 6-cm foam pad was placed on the floor so that the knee of the contralateral leg lightly touched it while descending; this was done to obtain the depth standard [10]. Ascending and descending motions were both measured for 2 seconds. During the exercise, the subjects were instructed to keep the trunk vertical and maintain the feet shoulder-width apart. Each exercise was performed three times, with a 1-minute rest period between each exercise.

Figure 2. (A) Forward lunge start position (backward lunge end position). (B) Lunge position. (C) Backward lunge start position (forward lunge end position). Forward lunge exercise order: A to C, backward lunge exercise order: C to A.
1) Electromyographic data collection

An EMG pad was attached to the rectus abdominis and erector spinae muscles to measure activity during forward and backward lunging [24-26]. The electrode attachment points were selected by referring to a previous study, and through direct palpation by the examiner (Figure 3). The attachment point for the erector spinae was 3 cm lateral to the spinous process of the third lumbar vertebra. The electrode for the rectus abdominis was attached 3 cm from the navel and above the anterior superior iliac spine. Since it is a unilateral exercise that targets the bending knee, all electrodes were attached to the same side of the trunk. Hairy areas were shaved to minimize resistance, and the skin at the attachment site was rubbed three or four times with thin sandpaper to remove the dead skin layer. Then, the skin was cleaned with alcohol, and the surface electrode was attached. The ground electrode was attached to the anterior superior iliac spine. The reference voluntary isometric contractions (RVIC) test required to normalize each muscle was measured before obtaining the EMG values of two different lunges. The posture for measuring RVIC test was based on previous studies. For the rectus abdominis, the subject’s arms were crossed at the chest, with the trunk bent while in the supine position until the inferior angle of the scapula increased. For the erector spinae, the subjects were asked to extend the trunk while in the prone position using the upper limbs (held next to the trunk) until the chest was lifted. All tests were performed without resistance, and the RVIC activity was repeatedly measured (three times for 5 seconds each). Then, the subject performed backward and forward lunges, and average RMS values for the rectus abdominis and erector spinae muscles were obtained. The RMS value was divided by the RVIC and multiplied by 100 (%RVIC) to calculate the activity of the rectus abdominis and erector spinae muscles during the backward and forward lunges.

Figure 3. Placement of electromyography electrodes. (A) Rectus abdominis. (B) Erector spinae.

4. Statistical Analysis

SPSS for Windows software (ver. 25.0; IBM Co., Armonk, NY, USA) was used to compare activation of the rectus abdominis and erector spinae between the forward and backward lunges. One-way repeated-measures analysis of variance was used to compare the muscle activities between the forward and backward lunges. When a significant difference was obtained, the post-hoc Bonferroni correction was applied. A p-value < 0.05 was considered significant.

The muscle activities of the rectus abdominis and erector spinae were measured during the forward and backward lunge exercises. The activities of the rectus abdominis and erector spinae during the ascending motion of the forward lunge were 54.75 ± 12.30 %RVIC and 52.09 ± 10.45 %RVIC, respectively, while during the descending motion they were 43.48 ± 11.94 %RVIC and 37.31 ± 9.03 %RVIC, respectively. The activities of the rectus abdominis and erector spinae during the ascending motion of the backward lunge were 50.33 ± 17.76 %RVIC and 72.94 ± 11.45 %RVIC, respectively, while during the descending motion they were 36.37 ± 11.28 %RVIC and 54.76 ± 15.70 %RVIC, respectively (Table 2). No significant difference was observed between the rectus abdominis and erector spinae muscle activities during the forward lunge, but a significant difference was detected during the ascending and descending motions of the backward lunge (Table 2). No significant difference in the activity of the rectus abdominis muscle was observed between the forward and backward lunges within the same part of the lunge, but the activity of the erector spinae muscle was significantly higher during the ascending and descending motions of the backward lunge (Figure 4).

Table 2 . Muscle activities during lunge exercises (%RVIC) (N = 12).

MuscleLunge exercises

FLAFLDBLABLD
Rectus abdominis54.75 ± 12.3043.48 ± 11.9450.33 ± 17.7636.37 ± 11.28
Erector spinae52.09 ± 10.4537.31 ± 9.0372.94 ± 11.45*54.76 ± 15.70*

Values are presented as mean ± standard deviation. RVIC, reference voluntary isometric contraction; FLA, forward lunge ascending; FLD, forward lunge descending; BLA, backward lunge ascending; BLD, backward lunge descending. *p < 0.05..


Figure 4. Muscle activity of the rectus abdominis (RA) and erector spinae (ES) to forward and backward lunge. BLA, backward lunge ascending; BLD, backward lunge descending; FLA, forward lunge ascending; FLD, forward lunge descending; RVIC, reference voluntary isometric contraction. *p < 0.05.

The rectus abdominis and erector spinae muscles of the trunk contribute to core stability and postural control of the trunk, and aid normal gait. In addition, training the trunk muscles through lower extremity rehabilitation exercises indirectly improves the alignment of the lower extremities and reduces the valgus force of the knee, thereby lowering the risk of ACL injury [12,20-23]. Therefore, it is important to understand the activity of the trunk muscles during the lunge exercise. The difference between the forward and backward lunges is that unlike the forward lunge, the backward lunge is performed blind. As vision plays an important role in maintaining balance during exercise, the backward lunge is expected to be more challenging than the forward lunge. Therefore, the purpose of this study was to compare activation of the rectus abdominis and erector spinae muscles during the forward and backward lunge exercises using EMG. No significant differences were observed in the activity of the rectus abdominis muscle, but the erector spinae muscle was significantly higher during the ascending and descending motions of the backward versus forward lunge. In addition, when comparing the two muscles for the same motion, erector spinae activity was significantly higher than rectus abdominis activity during ascending and descending motions of the backward lunge. Postural control mechanisms include feedforward control, which predicts and activates the muscles needed to perform the desired exercise through the central nervous system, and feedback control to rapidly regulate movement in situations where prediction is difficult [27]. In daily life, the human body is constantly subjected to mechanical forces in various directions, and is occasionally affected by mechanical forces even during a sudden postural perturbation or change [27,28]. In the case of the lunge exercise performed in this study, the movement was controlled by proactive activation of the trunk muscles through feedforward control before, and activation of the trunk muscles to cope with the sudden perturbation experienced during the exercise (feedback control). Previous studies have reported that visual information greatly contributes to feedforward and feedback control of the trunk muscles [28-32]. Therefore, it is reasonable to assume that the insufficient vision during the backward lunge could lead to a lack of feedforward control, which makes the body vulnerable to sudden perturbations and could trigger postural collapse. In turn, this could leads to greater activation of the erector spinae muscle as a result of feedback regulation. For the backward lunge, the toes touch the ground first, while for the forward lunge the heel touches down first, so the base of support is relatively narrow when landing. Along with the lack of visual information on the direction of movement, this likely lowers dynamic stability, thus requiring stronger neuromuscular regulation and proprioception and resulting in greater activation of the erector spinae muscles [31,32]. Another reason for the significantly higher muscle activity of the erector spinae during the backward lunge is that the trunk is maintained vertically as much as possible, and the toe-heel landing pattern leads to a larger extension moment than the forward lunge. In addition, the muscle activity of the erector spinae was highest during the ascending part of the backward lunge. Stronger concentric contraction is required during the ascending than descending part to overcome gravity.

Several limitations of this study should be discussed. First, the subjects were all healthy participants. Therefore, a comparative study on the effect of posterior lunge exercise on activation of the trunk muscles in subjects with musculoskeletal or nervous system damage in the lower extremities is needed. Second, as this study measured only the activities of the rectus abdominis and erector spinae during lunging, the activities of the deeper trunk muscles, such as the transverse abdominis or multifidus, remain unknown. Third, as the number of subjects was small (N = 12), it is difficult to generalize the results. Fourth, since only the muscle activity of the one side of the trunk during lunging was measured, studies also measuring muscle activity on the opposite side of the trunk during lunging are needed. Finally, no kinematic data were obtained. In future studies, it will be necessary to address these limitations to more accurately determine the effect of lunge exercises on trunk muscle activation, and verify the clinical significance of these exercises.

The effects of forward and backward lunge exercises on trunk muscle activities were analyzed. The activity of the erector spinae was significantly higher than that of the rectus abdominis during the backward lunge, and erector spinae activity was significantly higher during the ascending and descending motions of the backward compared to forward lunge. These results are attributed to the lack of visual feedback, and toe-heel landing pattern of the backward lunge exercise, which requires strong neuromuscular control and proprioception to increase the extension moment; this is likely to lower dynamic stability. The backward lunge can be considered a rehabilitation exercise for activating the erector spinae muscles that requires greater motor control than the forward lunge exercise. Future studies should obtain kinematic data along with measurements of the activity of other trunk muscles.

No potential conflict of interest relevant to this article was reported.

Conceptualization: JKS. Data curation: JKS. Formal analysis: JKS. Investigation: WGY. Methodology: JKS. Project administration: WGY. Resources: JKS. Supervision: WGY. Validation: WGY. Visualization: WGY. Writing - original draft: JKS. Writing - review & editing: WGY.

  1. Park S, Chung C, Park J, Yang J, Panday SB, Lee J, et al. Comparative analysis of lunge techniques: forward, reverse, walking lunge. Paper presented at: 34th International Conference of Biomechanics in Sport; 2016 Jul 18-22; Tsukuba, Japan. p. 921-4.
  2. Bouillon LE, Hofener M, O'Donnel A, Milligan A, Obrock C. Comparison of muscle activity using unstable devices during a forward lunge. J Sport Rehabil 2019;29(4):394-9.
    Pubmed CrossRef
  3. Bourne MN, Williams MD, Opar DA, Al Najjar A, Kerr GK, Shield AJ. Impact of exercise selection on hamstring muscle activation. Br J Sports Med 2017;51(13):1021-8.
    Pubmed CrossRef
  4. Krause DA, Elliott JJ, Fraboni DF, McWilliams TJ, Rebhan RL, Hollman JH. Electromyography of the hip and thigh muscles during two variations of the lunge exercise: a cross-sectional study. Int J Sports Phys Ther 2018;13(2):137-42.
    Pubmed KoreaMed
  5. Muyor JM, Martín-Fuentes I, Rodríguez-Ridao D, Antequera-Vique JA. 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. PLoS One 2020;15(4):e0230841.
    Pubmed KoreaMed CrossRef
  6. Saeterbakken AH, Chaudhari A, van den Tillaar R, Andersen V. The effects of performing integrated compared to isolated core exercises. PLoS One 2019;14(2):e0212216.
    Pubmed KoreaMed CrossRef
  7. Harvie D, O'Leary T, Kumar S. A systematic review of randomized controlled trials on exercise parameters in the treatment of patellofemoral pain: what works? J Multidiscip Healthc 2011;4:383-92.
    Pubmed KoreaMed CrossRef
  8. Jönhagen S, Halvorsen K, Benoit DL. Muscle activation and length changes during two lunge exercises: implications for rehabilitation. Scand J Med Sci Sports 2009;19(4):561-8.
    Pubmed CrossRef
  9. Pincivero DM, Aldworth C, Dickerson T, Petry C, Shultz T. Quadriceps-hamstring EMG activity during functional, closed kinetic chain exercise to fatigue. Eur J Appl Physiol 2000;81(6):504-9.
    Pubmed CrossRef
  10. Alkjaer T, Simonsen EB, Peter Magnusson SP, Aagaard H, Dyhre-Poulsen P. Differences in the movement pattern of a forward lunge in two types of anterior cruciate ligament deficient patients: copers and non-copers. Clin Biomech (Bristol, Avon) 2002;17(8):586-93.
    Pubmed CrossRef
  11. Khaiyat OA, Norris J. Electromyographic activity of selected trunk, core, and thigh muscles in commonly used exercises for ACL rehabilitation. J Phys Ther Sci 2018;30(4):642-8.
    Pubmed KoreaMed CrossRef
  12. Mattacola CG, Jacobs CA, Rund MA, Johnson DL. Functional assessment using the step-up-and-over test and forward lunge following ACL reconstruction. Orthopedics 2004;27(6):602-8.
    Pubmed CrossRef
  13. Boling M, Padua D, Marshall S, Guskiewicz K, Pyne S, Beutler A. Gender differences in the incidence and prevalence of patellofemoral pain syndrome. Scand J Med Sci Sports 2010;20(5):725-30.
    Pubmed KoreaMed CrossRef
  14. Ekstrom RA, Donatelli RA, Carp KC. Electromyographic analysis of core trunk, hip, and thigh muscles during 9 rehabilitation exercises. J Orthop Sports Phys Ther 2007;37(12):754-62.
    Pubmed CrossRef
  15. Goulette D, Griffith P, Schiller M, Rutherford D, Kernozek TW. Patellofemoral joint loading during the forward and backward lunge. Phys Ther Sport 2021;47:178-84.
    Pubmed CrossRef
  16. Marshall PW, Murphy BA. Core stability exercises on and off a Swiss ball. Arch Phys Med Rehabil 2005;86(2):242-9.
    Pubmed CrossRef
  17. Yu SH, Park SD. The effects of core stability strength exercise on muscle activity and trunk impairment scale in stroke patients. J Exerc Rehabil 2013;9(3):362-7.
    Pubmed KoreaMed CrossRef
  18. White SG, McNair PJ. Abdominal and erector spinae muscle activity during gait: the use of cluster analysis to identify patterns of activity. Clin Biomech (Bristol, Avon) 2002;17(3):177-84.
    Pubmed CrossRef
  19. Wirth K, Hartmann H, Mickel C, Szilvas E, Keiner M, Sander A. Core stability in athletes: a critical analysis of current guidelines. Sports Med 2017;47(3):401-14.
    Pubmed CrossRef
  20. Baratta R, Solomonow M, Zhou BH, Letson D, Chuinard R, D'Ambrosia R. Muscular coactivation. The role of the antagonist musculature in maintaining knee stability. Am J Sports Med 1988;16(2):113-22.
    Pubmed CrossRef
  21. Hewett TE, Myer GD, Ford KR, Heidt RS Jr, Colosimo AJ, McLean SG, et al. Biomechanical measures of neuromuscular control and valgus loading of the knee predict anterior cruciate ligament injury risk in female athletes: a prospective study. Am J Sports Med 2005;33(4):492-501.
    Pubmed CrossRef
  22. Manske RC, Prohaska D, Lucas B. Recent advances following anterior cruciate ligament reconstruction: rehabilitation perspectives: critical reviews in rehabilitation medicine. Curr Rev Musculoskelet Med 2012;5(1):59-71.
    Pubmed KoreaMed CrossRef
  23. Myer GD, Ford KR, Brent JL, Hewett TE. The effects of plyometric vs. dynamic stabilization and balance training on power, balance, and landing force in female athletes. J Strength Cond Res 2006;20(2):345-53.
    Pubmed CrossRef
  24. Calatayud J, Casaña J, Martín F, Jakobsen MD, Colado JC, Gargallo P, et al. Trunk muscle activity during different variations of the supine plank exercise. Musculoskelet Sci Pract 2017;28:54-8.
    Pubmed CrossRef
  25. Roth R, Donath L, Faude O, Cresswell AG. Trunk muscle activity during different types of low weighted squat exercises in normal and forefoot standing conditions. J Sports Sci 2020;38(24):2774-81.
    Pubmed CrossRef
  26. Shadmehr R, Mussa-Ivaldi FA. Adaptive representation of dynamics during learning of a motor task. J Neurosci 1994;14(5 Pt 2):3208-24.
    Pubmed KoreaMed CrossRef
  27. Abboud J, Nougarou F, Lardon A, Dugas C, Descarreaux M. Influence of lumbar muscle fatigue on trunk adaptations during sudden external perturbations. Front Hum Neurosci 2016;10:576.
    Pubmed KoreaMed CrossRef
  28. de Santiago HA, Reis JG, Gomes MM, da Silva Herrero CF, Defino HL, de Abreu DC. The influence of vision and support base on balance during quiet standing in patients with adolescent idiopathic scoliosis before and after posterior spinal fusion. Spine J 2013;13(11):1470-6.
    Pubmed CrossRef
  29. Krishnan V, Aruin AS. Postural control in response to a perturbation: role of vision and additional support. Exp Brain Res 2011;212(3):385-97.
    Pubmed CrossRef
  30. Maaswinkel E, van Drunen P, Veeger DJ, van Dieën JH. Effects of vision and lumbar posture on trunk neuromuscular control. J Biomech 2015;48(2):298-303.
    Pubmed CrossRef
  31. Ansari B, Bhati P, Singla D, Nazish N, Hussain ME. Lumbar muscle activation pattern during forward and backward walking in participants with and without chronic low back pain: an electromyographic study. J Chiropr Med 2018;17(4):217-25.
    Pubmed KoreaMed CrossRef
  32. Hoogkamer W, Massaad F, Jansen K, Bruijn SM, Duysens J. Selective bilateral activation of leg muscles after cutaneous nerve stimulation during backward walking. J Neurophysiol 2012;108(7):1933-41.
    Pubmed KoreaMed CrossRef