cardio training: part 2

Let me make one point before I continue.  If distant running is one's sport, one's passion, than by all means, continue the journey.  Longer, steady-state cardio will bring health benefits too.  However, in the quest for low body fat, while preserving muscle mass, interval training is your ticket.

Shorter Interval Cardio

• fat and glucose provide the initial sources of fuel though glucose is a much larger contributor
• interval training never allows the body to adapt
• a body that cannot adapt is inefficient at fuel utilization, so it uses more of it, which is what we want, right
• higher caloric output in a short period
• the heart and lungs are forced to keep up with the continual fluctuations, thus improving cardiovascular function
• interval training creates a massive post-exercise metabolic disturbance, which equates to a significant energy expenditure during recovery (= fat on its way out)

Slower Steady-State Cardio

• fat and glucose provide the initial sources of fuel 
• fat eventually become the primary source of fuel due to its aerobic nature (presence of oxygen)
• the body eventually adapts to steady-state cardio and becomes more efficient at fuel utilization, i.e., slows down the burning of fat as a fuel source
• lower caloric output
• heart and lung cardiovascular function remains mild in exertion
• the body returns to normal resting metabolism much sooner after completion

All you need to do is contrast a track athlete with an endurance athlete to know which protocol produces the better physique. 

Make it a great day!