Anaerobic power estimation using LASSO regression models of lumbar isokinetic parameters at different angular...

Anaerobic power production is not limited to the lower extremity muscles but is also closely related to the stabilization and endurance capacity of the trunk muscles. In particular, the isokinetic properties of the lumbar region muscles may be associated with short-term high-intensity physical performance. The aim of this study was to evaluate the associations between lumbar region isokinetic strength parameters and body composition variables obtained at angular velocities of 60°/s and 240°/s with anaerobic power.

In the study, regularized regression analysis (LASSO) with leave-one-out cross-validation (LOOCV) was applied using isokinetic variables such as peak torque (PT), total work (TW), and average power (AP) measured at angular velocities of 60°/s and 240°/s, along with body composition parameters (body fat percentage, body mass index, fat-free mass). Anaerobic power was used as the dependent variable.

At 60°/s, isokinetic parameters alone demonstrated limited predictive ability (LOOCV R ² = 0.19), although several variables such as total work and peak torque were retained in the model. When body composition variables were included, explanatory performance improved substantially (LOOCV R ² = 0.81), with fat-free mass (FFM) and fat mass emerging as the most stable predictors. At 240°/s, isokinetic parameters alone showed no meaningful predictive ability (LOOCV R ² = -0.18), indicating poor generalizability. However, when body composition variables were added, model performance increased markedly (LOOCV R ² = 0.80), with FFM, fat mass, and fat percentage demonstrating consistent associations with anaerobic power.

Lumbar isokinetic strength parameters showed limited and unstable associations with anaerobic power when considered independently. However, the inclusion of body composition variables, particularly fat-free mass, substantially improved model performance. These findings suggest that anaerobic power is more strongly associated with body composition than with isolated lumbar isokinetic strength parameters, and that the contribution of trunk muscle function may be secondary and context-dependent.