The sport of hiking is really great for both getting you in cardiovascular shape and improving your strength and muscle tone.
When training for hiking you are really going to want to pay attention to your leg muscles.
You will need to train them with both an endurance and strength fashion since they are going to have to be strong in order to support your bodyweight up hills or mountains but they will also have to be able to generate ongoing contractions since hiking is a longer durance activity.
In order to do that you should devote half your weight training to strength and the other half to endurance weight lifting. This is done by lifting in the rep range of 1-8 reps for strength, usually performing 3-6 sets per workout. Since you are not lifting for as many repetitions you will be able to use a heavier weight thus increasing your strength. Also remember to take longer rest periods between sets so as to allow your muscles full recover so you can lift maximally during the next set.
For endurance training, you want to target the 12-20 rep range for 1-3 sets, using a lighter weight than in the former example. You will also want to reduce your rest periods between sets since this will help to train your body to deal with lactic acid better, which is the by product that is generated during strength training. You will likely feel quite fatigued by the end of these workouts because of this, but you can help that by performing a good cool down of walking on the treadmill for 10 minutes after the training. This will help to deliver more oxygen to your muscles and remove this lactic acid.
Also be sure to allow for days of rest between both sessions so you can let your body recover. By following a good program you can definitely see your performance in this activity improve.