Knee flexor and extensor torque ratio in elderly men and women with and without obesity: a cross-sectional study.

BACKGROUND

With aging and obesity lower limb torque deteriorates. Importantly, the ratio between knee flexor (KF) and extensor (KE) torque is an indicator of joint stability.

AIMS

We compared KF torque and KF/KE ratio in older subjects of both sexes with obesity (OB) or without (NOB) obesity.

METHODS

The maximal torque during KE and KF isokinetic contractions were evaluated at: 60, 90, 150, 180 and 210 deg/s in 89 elderly (68 ± 5 years) subjects with NOB (BMI < 30 kg/m) and OB (BMI ≥ 30 kg/m). Values were normalised for body weight (BW) and leg lean mass (i.e., muscle quality).

RESULTS

At all speeds men had higher absolute KF values (P < 0.001). When values were normalised for BW, sex differences remain in favour of men (P < 0.001) with lower values in both groups with OB than NOB (P < 0.001). Muscle quality and KF/KE ratio were lower in OB than NOB (P < 0.001).

CONCLUSIONS

The KF torque and KF/KE ratio decline with aging and with OB. In all groups, the KF/KE ratio was below the joint stability threshold. Thus, exercise physiologists should include exercises designed to train both KE and KF in older subjects with OB.