exercise for huskies

Question
We are fostering a one-year-old female husky until we can find a permanent home. We have had her neutered and have managed to house train her. We are walking her several times a day on the leash - usually 2 walks of an hour each. Her energy outside seems endless. She pulls constantly on the leash and is always trying to follow a scent (we live in the country). We cannot let her run free because she takes off and doesn't come when called. What is the minimum reasonable amount of exercise that a husky should get per day? And how much weight can one young husky pull. Could she pull one adult of 150 lbs on a light weight sled? And finally, how do huskies manage the heat in the summer? Do they continue to require as much exercise?

Answer
Since it is a working breed they require quite a bit of work, but per dog it can be diffrent. I have one girl that one run down the road on the trikcycle is just perfect and she is set for the day and then some that can't get enough. I have a large fenced in lawn though and let them play with each other until they are tired.
  When it gets hot out you might want to take her swimming or something that will keep her cool while she exercises. Because she will still need the exercise but some can tolerate heat and some cannot. I have one boy in particular that refuses to go outside during the day when it is hot out, as soon as the sun in down he wants outside to run around. I usually have 2 or 3 kiddie pools in my lawn for them so they can cool off their feet and dig around in the water. As long as water is supplied they are good. If a fence isn't possible putting out a zip line type tie out will help.
http://www.amazon.com/dp/B0006G5AEE/ref=asc_df_B0006G5AEE1409894?smid=A1SV1BYDTU...

It goes between 2 trees or poles and it gives them the freedom to run a bit without tangling themselves up in it to much.

Or Invisible fencing is good, but you need to train them and be outside to watch them because a Siberian will still go through it if they feel the need to (chase a cat or small animal).

Siberians are on leash dogs. Not coming when called is normal. It is something that this breed is known for is not listening.
Here is something on The behavior info on a Siberian. This is to better understand what you are working with.
http://www.siberianrescue.com/seneca.htm

Any more Q's please ask!
-Michelle B