Workout 15-15-15: This workout does not need much more explanation. So easy and effective was it that it required such illustrious endorsements as Jennifer Aniston out flaunting it. This workout has been designed to cut through the thicket of gym culture hiding one’s self behind the walls of modern society. A triad-like combination of three different types of cardio that, within a period of 45 minutes, complete a whole. For all those interested, here are nine points to sum up the 15-15-15.
General Layout

The name kind of indicates it: 15 for cycle (spinning), 15 for elliptical, and 15 for running or treadmill. All these three are a neat conclusion of 45 minutes cardio and still with your heart pumping without boring the ass off on one machine.
Boredom Killer

Cardio’s biggest enemy is, arguably, boredom setting itself into the mentality of a human being; so, for those willing to stare off into space for an hour while keeping his heart pumping. Fifteen-minute ‘sprints’ just busted that for you: Just when you’re starting to get bored or feel tired with one movement, it’s time to switch into the next-the whole time keeping your mind going and just flying through a workout.
Balanced Muscle Recruitment

All those machines isolate their muscle group: bicycle works those quads and glutes, elliptical is low-impact for upper and lower body, and the treadmill simply hammers away at posterior chain and core. This way, alternating work really keeps you from stressing a single muscle group too much.
Good Calorie Burn

Because you stayed at this aerobic range for the entire 45 minutes, you burned quite a few calories. And the quick change from one machine to another really keeps the metabolism running. A lovely little mix for cardiovascular fitness or weight control without being in the gym for more than an hour.
Low Impact Transition

Beginning low impact with either bike or elliptical creates a readiness in the joints for transition into either a higher level of intensity of exercise running. The progressive impact works much better on either the knees or the ankle joints than hammering just for 45 minutes straight on the treadmill does. Hence, suitable for any level of exercise.
Personalization Is a Snap

The 15-15-15 is more of a guideline than a hard-and-fast rule. Let’s imagine your gym happens to lack a proper elliptical machine; you could just replace 15 minutes on the elliptical with 15 minutes on the rowing machine or jumping rope. There are also various intensity levels: keep it moderate, steady-paced or interval train within each 15-minute block-faster with slower-and so on.
Stroke Volume Strengthens

This trains endurance; when a person takes part in a training session of 45 minutes in some other modality of training and this happens to a person’s heart; it pumps better blood to lungs, processes better oxygen so that at the base of fitness, the person is now quite fit for long-distance hiking or racing or busy-day living.
No Need for Fancy Equipment

The fact that this workout holds good for all the universally available machines makes it popular in almost every gym. No secret lifting; no complicated app to follow-pedal, slide, run; workout out of your way should be already half-done.
Clears Head & Stress Relief

Long-duration cardio exercise has also generated endorphin molecules giving rise to the “runner’s high.” For many, when long, arduous cardio kicks in, it’s that sweet spot where all thoughts clear out of mind-all stress and burden in mind-and one is chirpy till the end of the day.