30 SECONDS TO THE FOUNTAIN OF YOUTH

The time course of the human growth hormone response to a 6 second and a 30 seconds cycle ergo meter sprint.

High Intensity Exercise Exponentially Boosts Growth Hormone

Stokes KA, Nevill ME, Hall GM, Lakomy HK.

Source

Department of Physical Education, Sports Science and Recreation Management, Loughborough University, UK.

The study also showed that the 30 second sprint raised HGH levels by up to 530% over the resting baseline.  Baseline is what your normal sedentary average resting hgH secretion is.

An exercise intensity above lactate threshold and for a minimum of 10 minutes facilitates a push secretion of hGH. Exercise exertion above the lactate threshold(With a higher exercise intensity the lactate level in the blood reaches the 'anaerobic threshold, the onset of blood lactate accumulation) intensifying the pulsatile release of hGH during the delta wave sleep cycle, increasing 24-hour hGH secretion.”

Abstract

Exercise is a potent stimulus for the release of human growth hormone (hGH)

The highest measured mean serum hGH concentrations after the 30 s sprint were more than 450% greater than after the 6 s sprint.

Repeated bouts of aerobic exercise within a 24-hour period result in increased 24-hour integrated GH concentrations. Because the GH response to acute resistance exercise is dependent on the work-rest interval and the load and frequency of the resistance exercise used, the ability to equate intensity across different resistance exercise protocols is desirable.

While exercise interventions may not restore GH secretion to levels observed in young, healthy individuals, exercise is a robust stimulus of GH secretion. The combination of exercise and administration of oral GH secretagogues may result in greater GH secretion than exercise alone in individuals who are older or have obesity. 

Dr. Colgan wrote an article in the 1990's that a full throttle 30 second sprint, would increase growth hormone 10 fold.