Best lunging gadget for building muscle tone

[rachyblue]

I'm looking for recommendations on what people to consider to be the best lunging gadget to build some muscle tone on an untoned youngster. I'm looking for the best gadgets and/or exercises to build his core strength ahead of him doing some ridden work.

 

[PolarSkye]

Long rein him up and down hills. I do use gadgets sometimes, but I just believe that natural, correct exercise is the best way to build muscle. Oh, and you could try ride and lead.

P