AUTHOR=Earp Jacob E. , Angelino Domenic , Hatfield Disa L. , Colantuono Vincent , Jackson Euan R. , Morgan Kristin D. , Adami Alessandra , Melanson Kathleen J. , Blazevich Anthony J. 

TITLE=Differing hypertrophy patterns from open and closed kinetic chain training affect quadriceps femoris center of mass and moment of inertia

JOURNAL=Frontiers in Physiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2023.1074705

DOI=10.3389/fphys.2023.1074705

ISSN=1664-042X

ABSTRACT=<p><bold>Purpose:</bold> To determine whether kinetic chain pattern during knee extensor strength training influences quadriceps femoris center of mass and moment of inertia about the hip in a predictable manner as such changes can affect running economy.</p><p><bold>Methods:</bold> Twelve participants completed 8 weeks of both unilateral open (OKC) and closed (CKC) kinetic chain resistance training on opposing legs. Changes in quadriceps femoris muscle volume (VOL<sub>QF</sub>), center of mass location (CoM<sub>QF</sub>), and moment of inertia (<italic>I</italic><sub>QF</sub>) about the hip were determined from magnetic resonance images scans. Regional hemodynamics of the vastus lateralis taken at 30% and 70% of muscle length during OKC and CKC bouts early in the training program were measured using near-infrared spectroscopy (NIRS) and used <italic>post hoc</italic> to predict changes in CoM<sub>QF</sub>.</p><p><bold>Results:</bold> While increases in VOL<sub>QF</sub> were similar between OKC (Δ79.5 ± 87.9 cm<sup>3</sup>) and CKC (Δ60.2 ± 110.5 cm<sup>3</sup>, <italic>p</italic> = 0.29), the patterns of hypertrophy differed; a distal shift in CoM<sub>QF</sub> (Δ2.4 ± 0.4 cm, <italic>p</italic> &lt; 0.001) and increase in <italic>I</italic><sub>QF</sub> (Δ0.017 ± 0.014 kg m<sup>2</sup>, <italic>p</italic> &lt; 0.001) occurred in OKC but not in CKC (CoM<sub>QF</sub>: Δ-2.2 ± 2.0 cm, <italic>I</italic><sub>QF</sub>: Δ-0.022 ± 0.020 kg m<sup>2</sup>, <italic>p</italic> &gt; 0.05). Regional hemodynamics assessed by NIRS during a single training session displayed similar exercise and regional differences and predicted 39.6% of observed changes in CoM<sub>QF</sub>.</p><p><bold>Conclusions:</bold> Exercise selection influences muscle shape sufficiently to affect CoM<sub>QF</sub> and <italic>I</italic><sub>QF</sub>, and these changes may be predicted in part from NIRS measurements during a single workout. Given <italic>I</italic><sub>QF</sub> is inversely related to running economy and since CKC exercise provides a more proximal pattern of hypertrophy than OKC, it may be more preferential for running. The results from the present study also highlight the potential of NIRS as a tool for predicting patterns of hypertrophy between different exercises and exercise conditions.</p>