front squats work very well for the quads.. thts the only alt.tht i can think of.. and yes ive grown out of certain maneuvers and had to find alt... but i like tht because its makes u a better trainer in troubleshooting problem and sticking points tht you eventually have to overcome..

fyi.. front squating takes a very strict form and a strong lumbar or u can really hurt ur back.. im sure thtu already know this...

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