What do heart warm ups do?

Can a smoker recover their cardiovascular fitness? What is walking good for? How can I effectively perform the hanging knees to elbows exercise for maximum core engagement and strength building? When were Sweatpants invented? What are the differences between felt and magnetic resistance in exercise equipment? Are addidas F60 shoes coming out? Is a treadmill a treadmill if it doesn't have handles? I live in Thailand and I wearing sneaker size40 and now I would like to buy jordan sneaker for man so what size is fit me? What is the significance of starting resistance in electrical circuits? What do you do when you sprain your knee? If i run for 30-45 minutes 3 times a week on top of doing kickboxing 3 times a week will i gain a ton of bulky muscle or will i lose weight I'm 5'7 16 years old and 130 pounds and i want to be 115? What does W stand for in woman's pant size? Do you need rest days from push ups if you are 14 and you want to improve fast? Steps walking mile? Is it true that if you do ab exercises the wrong way your abs will be rounded instead of flat? Why should you change your workout every 4-6 weeks? I need to find a good diet for a 13 year old she doesn't need or want to lose any weight and she wants to run half marathons and wants to be really healthy what foods does she need to eat? What are the most effective exercises to build and maintain 80 muscle mass in the body? What does the cardio respiration center do? What are the recommended daily intake percentages for macronutrients such as carbohydrates, proteins, and fats, with a breakdown of 50 carbohydrates, 30 proteins, and 20 fats?