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Related Experiment Video

Updated: Jun 25, 2026

Muscle Imbalances: Testing and Training Functional Eccentric Hamstring Strength in Athletic Populations

Muscle Imbalances: Testing and Training Functional Eccentric Hamstring Strength in Athletic Populations

Published on: May 1, 2018

Hamstrings activity during knee extensor strength testing: effects of burst superimposition.

Chandramouli Krishnan¹, Glenn N Williams

¹Department of Orthopaedics & Rehabilitation, University of Iowa Hospitals and Clinics, Iowa City, IA 52242, USA.

The Iowa Orthopaedic Journal

|February 19, 2009

Summary

Burst superimposition did not reduce hamstring activity during knee extensor testing. This method, used for assessing quadriceps strength, may slightly increase antagonist muscle engagement, potentially impacting strength measurements.

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Induction and Assessment of Exertional Skeletal Muscle Damage in Humans

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Published on: December 11, 2016

Area of Science:

Biomechanics
Sports Medicine
Musculoskeletal Research

Background:

Quadriceps muscle strength is a key indicator for recovery after knee injuries or surgery.
Antagonist muscle activity, particularly in the hamstrings, can influence knee strength measurements.
The burst superimposition method is a recognized standard for strength testing, but its effect on antagonist activity is unclear.

Purpose of the Study:

To investigate whether burst superimposition reduces hamstring muscle activity during knee extensor strength testing.
To determine the impact of burst superimposition on antagonist muscle engagement in healthy young adults.

Main Methods:

Isometric knee strength testing was conducted on 22 healthy young adults.
The burst superimposition method was employed during knee extensor strength tests.
Hamstring muscle activity was quantified immediately before and after burst superimposition.

Main Results:

Contrary to the hypothesis, a statistically significant increase in medial hamstring activity was observed with burst superimposition (7.23 vs. 9.62; P < 0.001).
Lateral hamstring activity also showed an increase, though it did not reach statistical significance (15.03 vs. 13.50; P = 0.087).
The observed increase in hamstring activity, despite statistical significance, is considered clinically negligible.

Conclusions:

Burst superimposition does not diminish, and may slightly increase, hamstring antagonist activity during knee extensor testing.
The findings suggest that the burst superimposition method's effect on antagonist co-contraction is minimal and likely not clinically relevant for strength assessment.