Split Squats (Lunges): Effect of Step Length and Angles

Split squats are a versatile lower body exercise that is a staple in many strength and conditioning programs. Biomechanical variables such as your stance, knee position, and torso position affect split squats and the muscles they target. Today, we will explore the effects of these variables and how to optimize the exercise to target muscles such as the: glutes and hamstrings, quadriceps, and calf muscles.

What Are Split Squats (Lunges)

The split squat is a static movement that involves the split-stance position. The split-stance position involves the legs shoulder width apart with one heel-raised foot stepped back along with the upper body maintaining an upright position. Once in the split-stance position, you lower yourself to the ground as low as possible without having the back leg touch the ground. You complete the split squat when you return to the original split-stance position. During the split squat, your feet remain statically planted on the floor.

People may also refer to split squats as lunges. However, lunges are actually a different movement where you dynamically step forward, backward, or sideways to complete the movement. Compared to a split squat, maintaining consistency with technique for a lunge is more challenging. Confusingly, the split squat is sometimes referred to as the “static lunge”.

Muscles Involved

Research indicates that split squats primarily engage the muscles attaching at the hip regardless of positioning, making them an effective exercise for targeting the glutes and hamstrings (Song et al., 2023). It is also a valuable exercise for quadriceps training – especially when squatting is challenging or when managing knee injuries (Schutz et al., 2014). 

Before dissecting the effects of changing different variables during a split squat, let’s get familiar with the primary movers of the exercise:

• Hip Extensors: The glutes and hamstrings are heavily engaged during split squats, contributing to hip extension and stabilization.
• Knee Extensors: Also known as the quadriceps, these muscles play a significant role in the movement. They contract to straighten the knees during the ascent and eccentrically contract to control the descent. 
• Ankle Plantar-Flexors: The calf muscles act to push the ankle back into a neutral position from the lowest portion of the exercise, as well as provide stability during the movement.

Maintaining an upright position will also involve the hip and knee extensors as well as ankle plantar-flexors for the following variations of split squat:

• Rear foot elevated squat
• Forward lunge
• Backward lunge
• Walking lunge

Biomechanical Variables of the Split Squat

Understanding the biomechanical principles behind split squats is essential for tailoring the exercise to target specific muscle groups, or for minimizing the amount of stress placed on the knee when nurturing an injury. Before exploring different ways to tailor this exercise, it’s important to understand a biomechanical term – Net Joint Moment (NJM). This measurement provides an estimation of the minimal muscular torque required for movement at a joint. We want to maximize the NJM for the muscles we want to specifically target.

Now, let’s delve into the effects of different variables such as step length, knee position, and trunk position on muscle engagement and loading.

Longer Step vs. Shorter Step

A longer step results in a smaller NJM at the front knee, but a larger NJM at the hip, preferentially loading the glutes and hamstrings (Shutz et al., 2014).

Conversely, a shorter step length creates a greater NJM at the front knee, preferentially loading the quadriceps (Shutz et al., 2014).

Knee Angle Positioning

The angle of the tibia (the angle of your shin bone relative to the ground) greatly influences knee positioning during split squats. A smaller tibia angle leads to the knee going over the toes and closer to the ground, while a greater tibia angle causes the shin to remain closer to vertical. 

Shutz et al. (2014) findings suggest that a smaller tibia angle results in a greater NJM and loading at both the front knee and hip, emphasizing the quadriceps, and glutes and hamstrings. No evidence is found by Shutz et al. (2014) that the knee shouldn’t move beyond the toes.

In contrast, a greater tibia angle reduces the NJM at the front knee and hip, but causes a greater NJM at the rear knee (Shutz et al., 2014). A greater tibia angle is beneficial to reduce knee loading at the front due to injuries while still allowing some training of the quadriceps, and glutes and hamstrings.

Effect of Trunk Angle

Maintaining an upright or slightly leaned-back torso increases the moment and loading on the front knee, resembling the upright torso in a squatting motion (Song et al., 2023). The upright position is useful for targeting the quadriceps.

However, leaning the torso forward increases the moment and loading on the front hip and ankle, resembling more of a hinge movement, like a Romanian deadlift (Song et al., 2023). Leaning forward helps minimize knee loading and emphasizes loading the hip.

Application of Research Findings

Based on the research findings, here are some strategies that can be applied:

• To target the quadriceps: the front knee should go over the toes, creating a tibia angle of about 60 degrees. Additionally, take a shorter, comfortable step, and maintain an upright torso position to further load the knee extensors (Shutz et al., 2014; Song et al., 2023)..
• To minimize knee loading (e.g., due to injuries): a longer step, greater tibia angle, and leaning forward are recommended to shift the loading to the rear leg as well as the hips (Shutz et al., 2014; Song et al., 2023).
• To emphasize loading the hip: take a longer step, lean your torso forward, and opt for a shorter tibia angle (Shutz et al., 2014, Song et al., 2023).

Conclusion

Understanding how different step lengths and angles during split squats affect muscle engagement is essential for optimizing training outcomes. By adjusting your step length, shin angle, and trunk position, individuals can effectively target specific muscle groups, making split squats a valuable addition to strength training or rehabilitation routines.

If you are wondering how you can tailor the split squat exercise to meet your needs, feel free to reach out to us today.

References

Schütz P, List R, Zemp R, Schellenberg F, Taylor WR, Lorenzetti S. Joint angles of the ankle, knee, and hip and loading conditions during split squats. J Appl Biomech. 2014 Jun;30(3):373-80.

Song Q, Ma M, Liu H, Wei X, Chen X. Effects of step lengths on biomechanical characteristics of lower extremity during split squat movement. Front Bioeng Biotechnol. 2023 Nov 10;11:1277493.