The Claim
In untrained young adults, performing barbell squats with a 4-second eccentric phase for 7 weeks produces the same increase in total quadriceps cross-sectional area as performing barbell squats with a 1-second eccentric phase for 7 weeks.
What the research says
Challenges is higher
Challenge is ahead, but a single strong supporting 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.
In untrained young adults, slowing down the lowering phase of barbell squats from 1 second to 4 seconds does not change the amount of muscle growth in the quadriceps after 7 weeks of training.
See the scientific wording
In untrained young adults, performing barbell squats with either a 4-second or 1-second eccentric phase for 7 weeks leads to similar increases in total quadriceps cross-sectional area, indicating that overall muscle growth is not significantly affected by eccentric tempo variation.
When you lower a heavy weight slowly, the muscle fibers under tension for longer grow bigger, especially the slow-twitch ones in the outer thigh muscle. This happens because the longer tension triggers more growth signals in those fibers. Even though the whole thigh gets bigger in both slow and fast lowering, the slow lowering makes one part grow more because of how the fibers respond to time under load.
What the research says
1 studySlowing down the downward motion of squats from 1 second to 4 seconds made one part of the thigh muscle (vastus lateralis) grow more than doing it fast, even though total thigh muscle growth looked similar. So, tempo does make a difference.
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.