It's not "resistance", but jumping rope is a fantastic, portable,
cheap (rope: 0.80/ft) exercise that can be done anywhere (don't need
to know the terrain around your camp site, nor endanger yourself in
traffic) and gives great results (a good abs workout, you wouldn't
think so!).

Why do you think boxers do this? It's not just for little girls. Try
doing 50 jumps without stopping!

Dave
--
Dave Carpenter

Whatever you wish for me,
May you have twice as much.