Ice bath or hot tub? Which one is better for sore muscles or injuries? I asked fitness pro and personal trainer  Dave Smith to give me some top tips on when to use ice and when to use heat. Read on! Canadian Living: After an intense workout or after competing in a sports event, is it best to use ice or heat to soothe aching muscles and help the body recover? Dave Smith:  You've likely seen professional athletes wearing huge ice packs on their knees after a game, or sometimes even sitting in a full-body ice bath. If the professionals do it then shouldn't we all ice down after a workout? Don't go filling your bathtub with ice just yet. When it comes to  choosing cold or hot treatment post-workout it is important to think about what you are treating and what you hope to achieve. I use a saying, "Ice for injury, hot for knots" to give people a general sense as to what they should be doing. Ice for Injury Injuries usually trigger an inflammation response from the body. The injured area gets hot, it may swell, and there is often pain. If you are in this situation then ice is the way to go. Ice acts as a natural pain-killer and also helps reduce the inflammation and swelling, which can speed up recovery. That's why the formula rest, ice, compression, elevation (RICE) has been the prescription for injuries for so many years. What about those pro athletes? If they are using ice does that mean they all injured? Injuries can happening because of a specific trauma such as rolling an ankle. This is called an acute injury and is what most people think of when they think of injuries in general. However, other injuries happen over time, often as a result of overusing specific muscles and joints. These injuries are called chronic and can still be treated with ice to deal with pain, inflammation and swelling. Adding heat to an acute or chronic injury can actually promote increased inflammation, which is exactly the opposite of what you want to do. Hot for Knots After a workout or a long day on the ski slopes you might feel soreness in your muscles. Most of the time this doesn't indicate injury - It is likely just the symptom of fatigue and muscle tightness. Sore, knotted, tight muscles need to be relaxed and heat can do the trick. Adding a heat pack to a sore lower back or achy shoulders can certainly relax those muscles and help them recover more quickly. What about ice? Ice cause muscles to contract, so icing muscles that are already tight runs the risk of creating painful muscles spasms. Nobody wants to deal with that. Your body does a good job of indicating what it needs but when in doubt just remember, "ice for injury, hot for knots". Dave Smith is a certified personal trainer who was recently named Canadian Fitness Professional of the Year. He specializes in bodyweight exercises and interval training that can be done anywhere. Check out his work at  makeyourbodywork.com. Photography courtesy of thinkstockphoto.ca