Higher volume weight training (ie 3 sets versus 1 set of each exercise) with short rest periods of approximately 1 minutes can stimulate a greater acute growth hormone realease (Kraemer 1991, 1993; Mulligan 1996). Growth hormone is lipolytic in adults. It is hypothesized that maximal effort is necessary for optimizing exercise induced secretion of growth hormone. Growth hormone release is related to the magnitude of exertion (Pyka 1992) and is attenuated with greater lactic acidosis (Gordon 1994).
Intense weight training utilizing multiple large muscles with longer rest between sets may also accentuate body lipid deficit by increasing post training epinephrine. Intramuscular triacylgycerol it thought to be an important energy substrate following repeated 30 second maximal exercise with 4 minute recovery intervals (McCartney 1996, Tremblay 1994). Rest periods lasting approximately 4 minutes between maximal exercise exercise of very short duration is required for almost complete creatine phosphate recovery required for repeated maximal bouts (McCartney 1986).
All of these little quotes are to disprove the theory of spot reduction and support how fat is lost evenly over the entire body, or how specific exercises use fat as fuel instead of another energy source.
The first part of this talks about GH. there are many factors that influence GH production and exercise is one of them. More exercise = more stimulated release of GH. GH is produced during deep sleep (stages 3 & 4) but is stimulated by exercise. Growth hormone also enhances the utilization of fat. Exercise + Deep sleep = more growth hormone production.
Epinephrine stimulates weight (fat) loss. This equals how ephedra works.
The last part of this talks about cellular energy production and use. Exercise is anaerobic or aerobic. Energy production is effected by time and intensity of exercise.
Here is a chart that explains what the energy pathways are:
ATP - Adenosine Triphosphate: a complex chemical compound formed with the energy released from food and stored in all cells, particularly muscles. Only from the energy released by the breakdown of this compound can the cells perform work. The breakdown of ATP produces energy and ADP.
PC - Phosphate-creatine: a chemical compound stored in muscle, which when broken down aids in the manufacture of ATP. The combination of ADP and PC produces ATP.
LA - Lactic acid: a fatiguing metabolite of the lactic acid system resulting from the incomplete breakdown of glucose. However Noakes in South Africa has discovered that although excessive lactate production is part of the extreme fatigue process, it is the protons produced at the same time that restrict further performance
O2 means aerobic running in which ATP is manufactured from food mainly sugar and fat. This system produces ATP copiously and is the prime energy source during endurance activitiesThese energy pathways are time duration restricted. In other words, once a certain time elapses that specific pathway is no longer used.
and some more:
Adenosine Triphosphate (ATP) stores in the muscle last for approximately 2 seconds and the resynthesis of ATP from Creatine/Phosphate (CP) will continue until CP stores are depleted, approximately 4 to 5 seconds. This gives us around 5 to 7 seconds of ATP production.
Once the CP stores are depleted the body resorts to stored glucose for ATP. The breakdown of glucose or glycogen in anaerobic conditions results in the production of lactate and hydrogen ions.
The aerobic energy system utilises proteins, fats and carbohydrate (glycogen) for resynthesising ATP.
A HIT exercise should last for about 20-30 seconds. During the 20-30 seconds your muscles doing the work will use all the ATP, all the Phospate Creatine, AND muscle glycogen. HIT also minimizes lactic acid production, which is promoted during multiple sets. Going to failure will also help to stimulate the production of GH.
Ulitmately, there is ALOT of stuff to put together in the right combination to maximize muscular growth and developement or fat lass.