I love intervals. They are convenient — you can do them anywhere and on any piece of equipment or without equipment — AND they are effective. With intervals, you alternate between bouts of high- and low-intensity training. This places a high metabolic demand on the body, burns lots of calories in a short amount of time, produces a high EPOC (post-workout calorie burn), increases mitochondria growth (mitochondria help to burn fat), and helps to improve one's fitness level. I also find that keeping track of the time and shifting speeds makes my workout go by faster.
Plus, they are a fantastic workout regardless of your fitness level; you adapt the interval intensity to fit your current capacity. Often people are wary of interval training. The myth is you have to be fit already to do them, but intervals are not just for athletes; you can do intervals without running stairs or sprinting until you puke. Intervals simply mean that you alternate between bouts of higher- and lower-intensity activity. The intensity of your interval is dependent on your individual fitness level. For some, the "high" interval will be walking quickly. For others, it might be jogging.
Think of interval training as highway vs city driving. When you come off of the highway, city driving seems slow, even though before you get on the highway, city driving didn't feel slow. It is your "norm." Driving faster while on the highway, or working at a higher level on a cardio machine, teaches your body to understand that your normal is slow, and thus helps to increase your fitness.
As an added bonus, intervals keep working out interesting. Too often people tell me they stopped training out of boredom. Of course people quit training if they find it boring — disliking something is a huge disincentive! So, give intervals a try; they are anything but boring!
Examples of "fun" intervals!!! (With that many exclamation marks how can you not believe they will be fun?!)
Workout 1: Easy pick-ups.
Warm up for five minutes. Do ten minutes at your regular speed (and regular level if you are on a machine that has levels). Then, cycle through the following pattern for ten minutes: alternate between thirty seconds at regular speed, twenty seconds slightly faster, and ten seconds fast. Finish with five to fifteen minutes at your regular speed and level. Cool down for five minutes.
Workout 2: Pyramid intervals.
Version A. Warm up for five minutes. Do one minute hard, one minute easy, two minutes hard, two minutes moderate, three minutes hard, three minutes moderate, four minutes hard, four minutes moderate, five minutes hard, one minute easy, and five minutes hard. Cool down for five to ten minutes.
Version B. Warm up for five to ten minutes. Then cycle through the following sequence: thirty seconds hard, thirty seconds recovery, sixty seconds hard, sixty seconds recovery, ninety seconds hard, ninety seconds recovery. Repeat three to six times. Cool down for five to ten minutes.
Workout 3: Mini pick-ups.
Warm up for five minutes. Do five minutes at regular speed. Alternate fifteen seconds hard with forty-five seconds moderate for ten minutes. Recover for two minutes. Then, repeat the intervals by alternating fifteen seconds hard with forty-five seconds at regular speed. Cool down for five to eight minutes.
Workout 4: "Brick" workout.
A "brick" workout is where you do two different activities back to back with no rest. As a triathlete I do brick workouts that combine swimming and biking or biking and running. You can use any piece of equipment. For example, use the rower and then the treadmill.
Brick Part 1: Do twenty minutes on any piece of equipment. Warm up for ten minutes. Do ten minutes at the hardest intensity you can hold.
Brick Part 2: Immediately start your second activity — do five minutes of moderate work. Then, do ten minutes at the hardest intensity you can hold. Finish with a five minute cool down.