Concurrent aerobic exercise interferes with the satellite cell response to acute resistance exercise
Lyle Babcock1, Matthew Escano, Andrew D'Lugos
1Department of Kinesiology, James Madison University, Harrisonburg, Virginia 22807, USA.
Summary
Concurrent exercise (CE) combining aerobic exercise (AE) with resistance exercise (RE) may blunt satellite cell (SC) response, hindering muscle growth. This study found RE alone boosted SCs, while CE diminished their response, particularly in slow-twitch muscle fibers.
Area of Science:
- Exercise Physiology
- Muscle Biology
- Sports Science
Background:
- Concurrent exercise (CE), combining aerobic exercise (AE) and resistance exercise (RE), may interfere with maximal muscle hypertrophy typically achieved with RE alone.
- Previous research suggests CE impacts myosin heavy chain (MHC) I fiber growth but not MHC IIa fibers, with the underlying mechanism remaining unclear.
- Satellite cell (SC) responsiveness is crucial for muscle adaptation, yet its specific response to acute CE has not been investigated.
Purpose of the Study:
- To investigate the fiber-type-specific satellite cell (SC) response following resistance exercise (RE), aerobic exercise (AE), and concurrent exercise (CE).
Main Methods:
- Eight college-aged males underwent two separate trials: one with unilateral leg extensions/presses (RE) and another with identical RE followed immediately by 90 minutes of cycling (AE/CE).
- Muscle biopsies were collected from the vastus lateralis pre- and 4-days post-exercise.
- Samples were analyzed for SC density, SC activation, and myosin heavy chain (MHC) fiber type using immunofluorescence staining.
Main Results:
- Satellite cell (SC) density increased significantly after RE (38 ± 10%) but showed a decrease after CE (-6 ± 8%).
- SC density within myosin heavy chain (MHC) I fibers increased following RE (46 ± 14%) but decreased after AE (-7 ± 17%) and CE (-8 ± 8%).
- The data suggest that performing AE immediately after RE attenuates the SC response, particularly in MHC I fibers.
Conclusions:
- The satellite cell (SC) response to resistance exercise (RE) is diminished when immediately followed by aerobic exercise (AE), impacting muscle fiber adaptation.
- This blunted SC response, especially in slow-twitch (MHC I) fibers, may impede the addition of myonuclei necessary for maximal muscle growth and force production.
- The physiological environment created by AE may interfere with the adaptive signaling pathways initiated by RE, highlighting potential interference effects in concurrent training.
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