When it comes to health - intensity is king.

Studies show that regular intense interval training (cycling, running, swimming) promotes a hormonal balance that favors the use of body fat, improvements in skin tone, growth of the brain, strengthening of bones, increased metabolic rate and so on. Intervals are best kept to a range of 30-90 seconds, repeated 8-10 times. Despite that fact that sessions are fairly short, it does take a toll on the body within the context of fatigue (depletes carbohydrate reserves in the muscles and liver). Because of this, no more than 2-3 sessions a week is recommended so as to avoid overtraining and burnout. From my seminar: 'can 60 be the new 40 - part 2'