Is Ultrasound an Accurate Method for Predicting Fat-Free Mass in Resistance-Trained Men?

Area of Science:

• Sports Medicine
• Human Physiology
• Biomedical Engineering

Background:

• Accurate assessment of fat-free mass (FFM) is crucial for monitoring muscle adaptations in resistance training (RT).
• Traditional methods like DXA are expensive and inaccessible for routine use.
• Ultrasound (US) presents a portable, cost-effective alternative for measuring muscle mass and quality.

Purpose of the Study:

• To develop and validate an equation using ultrasound (US) to predict whole-body (WB) and thigh FFM in adult men undergoing RT.
• To provide a practical tool for assessing FFM, addressing the lack of established US-based models for this population.

Main Methods:

• Seventy-nine resistance-trained men underwent DXA for WB and thigh FFM quantification.
• B-mode US imaging assessed vastus lateralis (VL) and rectus femoris (RF) muscle thickness (MT).
• Stepwise regression analysis developed US-based prediction equations, validated using the PRESS approach.

Main Results:

• VL and RF muscle thickness correlated significantly with body mass, WB, and thigh FFM.
• The US-based model using VL muscle thickness demonstrated strong predictive power for WB-FFM (R²=0.882, SEE=2.99 kg) and thigh-FFM (R²=0.849, SEE=0.667 kg).
• The VL-based model outperformed RF-based models in predicting FFM.

Conclusions:

• A statistically robust and practical mathematical model based on US measurements (VL-MT) was developed for assessing FFM in resistance-trained men.
• This US-based model offers an ecologically valid method for monitoring musculoskeletal adaptations.
• The model can aid in detecting muscle asymmetries and tracking progress in training and rehabilitation.