Effects of a Quadricep-Dominant vs. Functional Training Program on Activities of Daily Living, Functional Performance, and Motor Unit Recruitment in Older Adults.

The study investigated the effects of a quadriceps-dominant (QD) versus functional (FX) training program on the Functional Movement Screen (FMS), activities of daily living (ADLs), and motor unit (MU) recruitment of the vastus lateralis (VL) and biceps femoris (BF). Twenty-six older adults (68.9 ± 5.1yrs) were randomly assigned to a 6-week QD or FX training program. Participants completed ADLs, FMS, and three closed-kinetic chain exercises (CKCs): front lunge (FL), side lunge (SL), and bilateral squat (BLSQ), pre and post-intervention. Electromyography was recorded from the VL and BF during maximal voluntary isometric contractions (MVICs) and CKCs. Raw EMG recordings during CKCs were normalized to MVICs, and analyzed for root mean square (RMS). The QD program resulted in improved FMS performance during a deep-squat (p = 0.003), in-line lunge (p = 0.013), and hurdle step (p = 0.034), as well as improved ADL sit-to-stand (STS) and STAIRS (P < 0.05). Furthermore, the QD program resulted in greater RMS of the VL during CKCs (p < 0.05). Lastly, a positive correlation was observed between ADLs and RMS of the VL (p < 0.05, r > 0.6), whereas negative correlations were observed between FMS movements and RMS of the BF (p < 0.05, r < -0.6). The results suggest that a QD program may lead to greater improvements in functional movements, ADLs, and VL MU recruitment compared to a FX program. Additionally, MU recruitment of the VL is essential for functional ability, whereas high MU recruitment of the BF may coincide with reduced functional ability. The results of this study suggest that QD training may improve functional abilities in older adults.