The relationship between whole-body muscle mass and the isokinetic knee extensor strength of the non-operated side following anterior cruciate ligament reconstruction

Abstract

BACKGROUND:

Recovery of the isokinetic knee extensor strength on the operated side following anterior cruciate ligament (ACL) reconstruction is commonly calculated as a ratio with the value from the non-operated side serving as the denominator. However, the validity of the values of the non-operated side remains unclear.

OBJECTIVE:

This study aimed to determine the relationship between whole-body muscle mass and non-operated knee extensor strength after ACL reconstruction.

METHODS:

In 27 patients who underwent ACL reconstruction, muscle mass was measured using bioelectrical impedance analysis, and bilateral concentric knee extensor strength was measured using an isokinetic dynamometer at angular velocities of 60^∘/s and 180^∘/s. Correlation and single regression analyses were performed to examine the relationship between whole-body muscle mass and knee extensor strength.

RESULTS:

There was a strong to very strong positive association between whole-body muscle mass and non-operated knee extensor strength (60^∘/s: $r=$ 0.85, 180^∘/s: $r=$ 0.90, $P<$ 0.01). Univariate regression analysis showed that whole-body muscle mass was a strong predictor of non-operated knee extensor strength (R²= 0.71-0.81).

CONCLUSIONS:

Assessing both whole-body muscle mass and knee extensor strength may be used to determine whether muscle strength on the non-operated side is appropriate for the individual’s body composition.