Forward Trunk Lean During Lunge Exercise Increases Posterior Chain Activity

Research Review: Forward trunk lean during lunge exercise increases posterior chain activity

By David Chessen DPT, PT, MBA, CSCS

Edited by Brent Brookbush DPT, PT, COMT, MS, PES, CES, CSCS, ACSM H/FS

Original Citation: Farrokhi, S., Pollard, C. D., Souza, R. B., Chen, Y. J., Reischl, S., & Powers, C. M. (2008). Trunk position influences the kinematics, kinetics, and muscle activity of the lead lower extremity during the forward lunge exercise. journal of orthopaedic & sports physical therapy, 38(7), 403-409. ABSTRACT

Why the Study Is Relevant: The forward lunge is an exercise commonly used in rehab, fitness, and performance settings to improve lower extremity strength; however, a relatively small amount of research exists on how trunk position influences muscle activity. In this 2008 study, researchers at the University of Southern California investigated whether a change in trunk position would alter muscle activity and kinematics of the lead lower extremity. The findings suggest that a forward trunk increases muscle activity of the hip extensors, specifically the gluteus maximus and biceps femoris .

Caption: Sagittal Plane Lunge

Study Summary

Caption: Static Lunge to Row (Posterior Oblique Subsystem) Integration Progressions

Review & Commentary

This study contributes to a growing body of research comparing the muscle activity and kinematics of various exercises, or variations of exercises. This study compared activity of lower extremity muscles during a lunge performed with different trunk positions. The findings indicate that lunges performed in a trunk-forward position increase posterior chain activity.

The trunk-forward variation significantly increased the hip extensor impulse and hip extensor electromyography (EMG), specifically the gluteus maximus and biceps femoris . As would be expected in this variation, there is a concurrent increase in the vertical ground reaction force in the lead limb. The plantar flexor impulse was also increased. These results were attributed to the anterior translation of the center of mass relative to the hip joint and base of support.

The study had many methodological strengths, including:

• This study used both EMG and kinematic analysis to compare motion at several joints during variations of a commonly recommended exercise. This provides the reader with information regarding how joint and bone position may be related to muscle activity, and how changes in form during this common exercise may effect outcomes.
• The lunge is a commonly recommended exercise, performed in rehab, fitness, and performance settings. The use of a common exercise in this study increases it's clinical relevance/practical application.
• The study described a well thought-out protocol for positioning the subjects for the variations of the forward lunge, and used validated methods for recording EMG and kinematic data.

Weakness that should be noted prior to clinical integration of the findings include:

• The subject sample consisted of a group of young healthy individuals. Consideration should be given before attempting to apply these findings in an injured, or at risk population.
• There was no mention of a standardized method to ensure proper form. Based on the description it appears as if some common compensation patterns may have been allowed which could have effected outcomes.
• Participants were permitted to vary their joint kinematics in each lunge variation. This may have compromised the findings on whether trunk position is responsible for the results of the study.

Why This Study Is Important

This study adds to a growing body of research comparing exercises and variations of exercises. Comparative, practical research is essential for optimizing exercise selection. The lunge is a commonly recommended exercise in rehab, fitness, and performance settings, and may have high transference to activities of daily living (ADL's) and sport.

The combination of kinematic and EMG analysis, allows the human movement professional to make decisions about trunk position based on the client's goals or impairments, with the intent of affecting range of motion, muscle activity or both. Further, while joint motion can be seen and assessed, it is not possible to see the relative amounts of muscle activity. Studies like this one aid in moving beyond conjecture and hypothesis relative to the affect altered motion has on muscle recruitment. This study confirms the hypothesis that increased forward lean increases gluteus maximus and biceps femoris activity.

How the Findings Apply to Practice

This study implies that cuing a forward lean during a lunge will increase gluteus maximus and biceps femoris activity, as well as require greater range of motion (ROM) for hip flexion and dorsiflexion. If these increases coincide with a patient/clients goals, a forward lean may be recommended.

Related Brookbush Institute Content

As supported by this study, the Brookbush Institute recommends performing a front, reverse and/or static lunge with a forward lean to increase hip extensor activity. However, it is also noted in the Brookbush Institute Leg Strength Progression that these exercises require optimal dorsiflexion. For individuals exhibiting lumbopelvic hip complex dysfunction (LPHCD) , sacroiliac joint dysfunction (SIJD) , and/or lower leg dysfunction (LLD) it may be recommended that mobility and activation techniques precede resistance training. Further, it may be necessary to regress the exercise until optimal mobility and better muscular recruitment has been achieved. Has described in the article Leg Strength Progression the lunge is one of the last exercises to be integrated in a progression that includes leg press, ball wall squats, squats, step-ups, lunges and single leg squat touch downs.

Although not mentioned in this study, the Brookbush Institute also recommends using a forward lean during all progression of a lunge including static, dynamic, reverse, forward, frontal, transverse and integrated progressions.

Below are a few sample progressions of the lunge exercise:

Sagittal Plane Lunge

Static Lunge Row POS Integration Progression

Dynamic Lunge with Chest Press AOS Progression

Bibliography:

1. Farrokhi, S., Pollard, C. D., Souza, R. B., Chen, Y.-J., Reischl, S., & Powers, C. M. (2008). Trunk position influences the kinematics, kinetics, and muscle activity of the lead lower extremity during the forward lunge exercise. The Journal of Orthopaedic and Sports Physical Therapy, 38(7), 403–409.
2. Ford, K. R., Nguyen, A.-D., Dischiavi, S. L., Hegedus, E. J., Zuk, E. F., & Taylor, J. B. (2015). An evidence-based review of hip-focused neuromuscular exercise interventions to address dynamic lower extremity valgus. Open Access Journal of Sports Medicine, 6, 291–303.
3. Bouillon, L. E., Wilhelm, J., Eisel, P., Wiesner, J., Rachow, M., & Hatteberg, L. (2012). Electromyographic assessment of muscle activity between genders during unilateral weight-bearing tasks using adjusted distances. International Journal of Sports Physical Therapy, 7(6), 595–605.
4. Hofmann, C. L., Holyoak, D. T., & Juris, P. M. (2017). Trunk and Shank Position Influences Patellofemoral Joint Stress in the Lead and Trail Limbs During the Forward Lunge Exercise. The Journal of Orthopaedic and Sports Physical Therapy, 47(1), 31–40.
5. Riemann, B. L., Lapinski, S., Smith, L., & Davies, G. (n.d.). Biomechanical analysis of the anterior lunge during 4 external-load conditions. Journal of Athletic Training, 47(4), 372–8.

© 2016 Brent Brookbush

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