# The Reverse Lunge: A Descriptive Electromyographic Study
## 1 Introduction  
The lunge is a well-established therapeutic intervention that is commonly used by strength training and rehabilitation professionals to address the lower extremities (LEs) and core. One advantage of the lunge is its ability to isolate the quadriceps femoris better than other LE musculature in comparison to other compound movements, like the monopedal squat [1]. Lunges are versatile, allowing for modification of direction, upper extremity (UE) engagement, surface environment, addition/position of load, and perturbation(s). Given these possible modifications, the lunge can be utilized by many individuals and patient populations ranging from youth to geriatrics and sedentary to athletic. The varied utility of the lunge lies in the clinician's goal for the patient. Utilizing the aforementioned modifications, the goal of the lunge may include increasing quadriceps strength, core or LE stability, or improving balance [2]. This exercise is popular in rehabilitation for its versatility and functionality. Its applications include, but are not limited to, quadriceps strengthening postoperative (post-op) total knee arthroplasty (TKA) and anterior cruciate ligament (ACL) reconstruction, delaying mobility disability in the Parkinson's population, improving overall deconditioning, and generally in training of athletes [3]. Multiplanar lunges have been studied less extensively than other compound movements, like the back squat, hip thrust, and deadlift [4]. However, within the multiplanar lunge directions, the majority of research has focused on the forward lunge. In addition to the forward lunge, the lateral lunge has been more readily studied than a third variation: the reverse lunge. The forward and lateral lunge variations have been examinedin electromyographic studies investigating quadriceps/hamstrings co-activation and LE muscular activation of the glutel musculature, hamstrings, and quadriceps [1; 5]. There have only been a few studies that have examined the reverse lunge alongside forward and lateral lunges and other compound movements, such as split squats and barbell lunges, using electromyography (EMG) [5; 6; 7; 8; 9; 10]. EMG utilizes electrical signals produced from a muscle's motor units during muscle contraction to describe muscular activity [11]. Surface EMG was chosen for this study as it is non-invasive, eliminates the threat of needlestick infections or diseases, and allows for data collection regarding both the amplitude and timing of muscle activations during human movement [11]. In the reverse lunge variation, the moving limb moves in the opposite direction as it does during the forward lunge. The individual starts by standing erect with feet hip-width apart. The movement is initiated by having the individual step back, extending their hip to bring the moving (lead) limb posterior to the trunk. At this point both knees flex to approximately 90 degrees, allowing the center of mass to move inferiorly. The non-moving (stationary) limb eccentrically controls this movement. The stationary limb then concentrically brings the individual back to the starting position, while bringing the moving limb foot back to hip-width stance in an erect standing posture. Since studies of the reverse lunge are scarce in the literature, gaps in terminology exist regarding the descriptions associated with the reverse lunge. Concerning the exercise itself, a variety of names have been utilized. Although this study has chosen to use the name \"reverse lunge\", synonyms in the literature include \"transverse lunge\" and \"backward lunge\" [6]. Regarding the labeling of the LEs during the reverse lunge, there is no consensus on nomenclature. The term \"dominant limb\" has been utilized differently in studies [1; 12], which has created confusion as to what exactly characterizes a dominant LE during lumging and has resulted in a lack of standardization regarding the patients' characterization of their \"dominant\" LE [5; 6].