Cerny K.1, Adams J.1,2
1California State University, Long Beach, Department of Physical Therapy, Long Beach, United States, 2California State University, Northridge, Department of Physical Therapy, Northridge, United States
Background: Lunge exercises are used by physical therapists to exercise their clients' extensor muscles. Although the leading leg of the forward lunge has been studied for joint demand and muscle recruitment, the trailing limb of the forward lunge has not. Those that have studied muscle activity during the lunges have used surface electrodes which are prone to cross talk from adjacent muscles.
Purpose: To determine the impulse and muscle activity of the leading leg during backward and lateral lunges as well as of the trailing limb during the forward lunge.
Methods: Twenty-nine young adults with no history of recent lower limb injury were studied with intramuscular electromyography (WEMG) of the Soleus (S), Medial Gastrocnemius (MG), Vastus Lateralis (VL) and Lower Gluteus Maximus (LGMax) muscles and for hip, knee and ankle joint impulse of the leading limb during the lateral (LL) and backward lunge (BL) and of the trailing limb during the forward lunge (FL_TL). WEMG data were acquired using a band-pass filter of 20-1000 Hz, sampled at 2000 Hz. RMS values were normalized as percent maximum voluntary isometric contraction (%MVIC). Joint impulse was calculated by link segment modeling using an 8-camera optoelectric system and forceplates. Three trials were performed per exercise. Data were analyzed by Friedmans and Wilcoxin signed-rank tests with medians reported. The study obtained IRB approval from California State University, Long Beach.
Results: RMS EMG:
All lunges produced significantly more VL activity than MG and LGMax. BL and LL also recruited significantly more VL than S activity and more S than MG activity. S activity in FL_TL was statistically equal to both VL and MG activity. LGMax was silent in BL and FL_TL. VL, S, and LGMax were all significantly more recruited during the LL (47.2, 20.2, 18.5% MVIC, respectively) than other lunges while MG did not differ significantly across exercises, averaging 10.1 % MVIC.
IMPULSE:
All lunges produced significantly higher extension impulses at the knee than at the ankle however knee extension impulse did not differ across exercises, averaging 1.94 Nm/Kg*s. Hip impulse was extension only in LL (2.01 Nm/Kg*s). Extension impulse at the ankle was highest during FL_TL (1.68 Nm/Kg*s) and lowest in BL (0.32 Nm/Kg*s).
Conclusion(s): Lunge exercises produced the greatest extension impulse at the knee and the highest recruitment of the VL muscles. S was more highly recruited than G. The LL produced extension impulses at all 3 joints and recruited the most activity of the VL, S, and LGMax. The FL_TL produced an extension impulse at the ankle and knee and recruited almost equal activity of S, G and VL.
Implications: Physical therapists may use lunge exercises to recruit their clients knee extensors but should consider the LL for LGMax recruitment and for higher recruitment of VL and S.
Funding acknowledgements: This study is unfunded
Topic: Musculoskeletal: lower limb
Ethics approval: Approved by the IRB at California State University, Long Beach.
All authors, affiliations and abstracts have been published as submitted.
