The Claim
In untrained young adults, performing barbell squats with a 4-second eccentric phase for 7 weeks increases the contraction time (Tc) of the vastus lateralis and rectus femoris muscles, as measured by tensiomyography, suggesting a potential adaptation toward slower muscle fiber characteristics.
What the research says
Supports is higher
Support is ahead, but a single strong opposing study can change this.
These are independent scores, not a percentage. Higher-grade studies count more, so a single strong opposing study can outweigh several weaker ones.
If you're a young adult who hasn't trained much before and you do squats slowly on the way down for 7 weeks, your thigh muscles might start contracting more slowly, which could mean they're changing to work more like slow-twitch muscles.
See the scientific wording
In untrained young adults, performing barbell squats with a 4-second eccentric phase for 7 weeks increases the contraction time (Tc) of the vastus lateralis and rectus femoris muscles, as measured by tensiomyography, suggesting a potential adaptation toward slower muscle fiber characteristics.
When muscles are stretched slowly under heavy load, the slow-twitch fibers grow larger because they are better suited to handle long-lasting tension. These larger slow-twitch fibers take more time to contract and relax, which makes the whole muscle contract more slowly.
What the research says
1 studyIf you're new to lifting and do squats slowly on the way down for 7 weeks, your thigh muscles take longer to contract — which means they might be changing to work more like slow, endurance-type muscles.
Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting studies
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.