The Claim
In untrained young adults, performing squats with a 4-second eccentric tempo for 7 weeks increases the contraction time (Tc) of the vastus lateralis and rectus femoris muscles, which suggests an adaptation toward a greater proportion of slow-twitch muscle fibers in these muscles.
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 young people who don’t normally lift weights do squats slowly on the way down for 7 weeks, their thigh muscles might start working more like endurance muscles—slower but more tired-resistant.
See the scientific wording
In untrained young adults, a 4-second eccentric tempo during squats for 7 weeks increases the contraction time (Tc) of the vastus lateralis and rectus femoris muscles, suggesting an adaptation toward a greater proportion of slow-twitch muscle fibers in these muscles.
When muscles are stretched slowly under load, the slow-twitch fibers get worked harder for longer, causing them to grow bigger. These bigger fibers take longer to contract and relax because they process calcium more slowly and move their muscle proteins at a slower pace, which makes the whole muscle contract more slowly.
What the research says
1 studyWhen people who don’t lift weights do squats slowly on the way down for 7 weeks, their thigh muscles start contracting more slowly—like endurance muscles do. This study proved that exact thing happened.
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.