Leg strength is aided or supported by core exercises……abs and lower back so you need to add these in.
Leg strength
Squats with a barbell or dumbbells by the side
Lunges, walking or stationary
Leg Press…machine
Calf Extensions…..
ab exercises….crunches, birddog, plank, google ab exercises
hip flexibity exercises
Box jumps as above
Jumping from a standstill to a point
squat and the jump up
burpess
all of these with body weight
then add
hill climb intervals
fartlek
intervals 20 secs flat out and then 20 secs rest
as with all weights form over weight, do the exercise correctly so no injuries