These activities are cheap basics for avoiding a completely sedentary life. A sedentary life is roughly defined as over 4 hrs/day sitting with under 5 hours/week of some form of measurable exertion (consistently elevated heart rate above the walking level. Not Yoga, and weights and most sports don't really count as cardio time.). Getting out of the "sedentary" category to the "Lowest-level Active" is a very low bar for healthy people.
"Cardio" is obviously mainly about general vigor - heart conditioning plus muscle maintenance (rather than muscle-strengthening) and general endurance. Ordinary walking, as opposed to Strolling, hardly meets the minimal standard for "exercise" because it is non-exertional except for the elderly or the overweight. (Housework, strolling, gardening are too low-intensity to call exercise at all.) For most people, "walking" means a speed under 3.4 mph. "Brisk walking" or "Fast Walking" is any speed between around 3.5 mph and the point at which you have to break into a jog or a run (somewhere over 4 mph for most people).
More maybe-interesting info below the fold -
If you want to see thousands of people Fast Walking at once, walk around Manhattan at 5-6 AM. They aren't exercising - they are going to work at the Manhattan pace. I have suburban friends who walk 2-3 miles to and from work every day, but suburbia is all about cars so if you walk to work people might wonder whether you got nailed with a DUI.
Ordinary walking 5 hours/week will not burn fat, build any muscle, or build cardio endurance. What it can do is to maintain mobility and functionality. Fast Walking gets your breathing rate and heart rate up a little so it does more to maintain physical endurance.
We'll put Jogging and Slow Running in the "low-moderate" level. (Technically, "moderate" intensity cardio exercise means a heart rate at 50-70% of your max.) Jogging and running are more effective at building cardio and muscle endurance, but neither are effective at fat-burning or strength-building if you do them for an hour daily.
Fast Running and Climbing (eg Stairmaster, fast hill- walking) are higher-intensity cardio conditioning, but the gold standard for cardio conditioning is Sprinting (whether running, climbing, swimming, biking, etc). Sprinting consists of 30-second to 2-minute bursts of maximum effort. Sprinting is anaerobic, meaning that breathing cannot supply enough oxygen to continue the exertion for very long. It makes your heart work as hard as it can and stimulates added blood supply to muscles.
The most efficient cardio conditioning and training mixes sprints with lower-intensity effort. Again, these are all Cardio exercises which means they are about endurance and functionality, not strength. Are they good for muscle "toning"? Sure. That basically means that doing the exercise routinely will build a better blood supply to the muscles used so they can function more efficiently. Still, you will not lose any weight by doing that.
Where does recreational Hiking fit in? Hiking is for fun, to see stuff and to get to places. We try to stay in shape so we can do things like that for hours. Generally-speaking, it is walking but with multi-hour duration and with enough varied terrain that it's zero-moderate cardio except for the hard steeps. If you put a 40-lb pack on your back and hike up Mt. Madison, that can be a high-intensity and even strength-building exertion. For those purposes, though, the drawback is that it's unlikely that you would do that several times per week so any gain from that challenge will be rapidly lost because cardio fitness does not ratchet up unless it is routine.
Why do I like the treadmill for cardio? It is low impact, speed-adjustable, and incline adjustable. Keep that incline and speed as high as you can for decent intensity. Except for sprinting, road-running is, over time, terrible for joints no matter how enjoyable it is to get outdoors and cruise around. Avoid doing a lot of it if you want to stay functional when you turn 45.
Why do I like stair machines for a once-weekly part of my cardio? For the intensity and because it is low-impact, same as walking. For fun, you can vary the speed up and down as you go. When I began with that thing, I could barely do 4 minutes at the 4 setting. Now I can do half an hour, at which point I get bored and do something else to complete the hour on my "endurance day" - like jump rope, etc. That is a dramatic fitness improvement. If I had a mountain in my backyard, I'd use that instead but I usually do my exercising before work when it is still dark. I frequently see women doing their stairmaster cardio with weight vests. I figure they are either getting ready for hiking or skiing season, or just trying to tighten up their butts for sex-appeal. They do tend to have...never mind.
What's the easiest way to measure how well you are challenging and conditioning your heart and making your muscles do their job? It is how hard you are breathing. If you can speak a sentence, it's zero to low intensity. If a full sentence is tough without interruptions to breathe, it's moderate. If all you can utter are single-word expletives and brief complaints against God, it's high intensity or moving into anaerobic. Anaerobic bursts are the best way to ask your heart to toughen up. Generally, high intensity builds cardiac strength and endurance while low-moderate intensity maintains.
Reminder: Balanced Physical Fitness is a three-legged stool: Cardio, Calisthenics, and Strength -plus of course achieving decent body composition. We are just talking about some of the most common and (inexpensive - free) pure Cardio possibilities in this post.
