Forward by INBF Champ & TEAM 3DMJ Coach Eric Helms

I met Dr. Rita Bermudez and her two sons a few years back when they became my clients at a personal training studio here in Sacramento,California where I used to work. Since that time, I have been her coach, consultant and mentor for fitness and nutrition. I am honored that she has seen value in my approaches and methodologies and I am honored not only to still be working with her, but also to call her and her sons my close friends. 

Our relationship is a two way street.  Dr Bermudez is a specialist in rehabilitation and sports medicine and I trust her completely as my consultant and mentor in that regard. She is also my wife and I’s personal physician and she has played a huge part in my career as a power lifter and bodybuilder. She was instrumental in the recovery of my torn hamstring during my 2009 contest season. With her help I overcame that tear and went on to win two divisions, both times competing in overalls against none other than WNBF Pro Jeff Alberts. In the end, I nearly obtained my pro card taking a close second to WNBF Pro and WNBF World’s Middleweight Finalist Scott Kluth at the 2009 INBF West Coast Classic. This was my final and best showing of 2009 and I was pleased knowing that Rita was in the audience lending me her support. I am happy to say that my hamstring is now completely recovered and in fact I am hitting squat and sumo dead lift personal records on a regular basis!

Dr. Bermudez has an excellent grasp of exercise physiology and spends hours poring over research related to health, fitness, human performance, body fat reduction and gaining lean muscle. She has aspirations of competing as a natural bodybuilder herself and has built quite the physique training alongside myself and her two sons over the last few years. 

Here at 3DMJ we are honored to have her as a contributing guest author. Her review of High Intensity Interval Training that follows is of the highest quality with many applications to the natural lifter. I look forward to her future contributions and I would recommend her as a physician to any serious athlete who lives in the Sacramento area. Her private practice, “Capital Rehab”, is located in downtown Sacramento at 630 Alhambra Boulevard.

High Intensity Interval Training

Rita B Bermudez, MD, MSEE

Board Certified in Sports Medicine, Physical Medicine and Rehabilitation

It has been well demonstrated that endurance training has a negative impact on power-strength training.[1] With prolonged endurance training, the body will shift towards breaking down muscle in order to use the protein for energy.  This is of particular concern to the natural bodybuilder, who needs to ensure that the effort to build muscle is not impeded by aerobic training in the effort to reduce body fat and stimulate muscle hypertrophy.  

Generally, with aerobic exercise, the predominant fuels are glycogen and fatty acids.  However, muscle proteins are used for aerobic exercise as glycogen stores reach depletion. Typically, one can engage in moderate exercise for about 45 minutes before depleting glycogen stores (assuming they were full in the first place).  In fact, as much as 15 % of the energy required for activity can come from break down of muscle tissue when glycogen stores are depleted.  

One could try to evade muscle degradation by eating during a work out or by limiting the exercise session to about 45 minutes.  However, that would still not avoid an even more detrimental effect of muscle fiber conversion.  Specifically, Type IIb fibers, which primarily use glycogen for fuel, may be replaced by type IIa oxidative fibers as a result of prolonged endurance training.  Yet, power athletes want to preserve these glycolytic type IIb fibers because they are the ones that are primarily recruited for activities that require a lot of strength in a short time – like jumping or doing a power lift. This change in fiber type with endurance training was demonstrated by a study on sprinters who were exposed to endurance training. Those who did the endurance training actually decreased their vertical jump distance as compared to those sprinters who didn’t do endurance training. 

Of course, one could just avoid doing prolonged aerobic exercise altogether, but then strength/power athletes would still need a way to improve cardiovascular conditioning and, bodybuilders in particular, would like a way to achieve low levels of body fat. In addition, power lifters need a way to improve anaerobic metabolism, since it is through this pathway that most of the energy is provided for rapid high-power output. It has been estimated that a world-class weightlifter can produce a power output that is 10 to 20 times Vo2max[[1]2].  (Compare this with a sprint runner at 3 to 5 times VO2 max). 

Enter, high intensity interval training. (HIIT) 

HIIT, as you are aware, involves intermittent short bursts of high intensity activities mixed with a lower intensity aerobic activity. The idea is to perform the exercise as hard as one can for a short duration and then slow the activity down to get some relative rest and recovery, but not completely drop the heart rate to baseline. 

WNBF Pro & TEAM 3DMJ Coach - Brad Loomis, perfoming a session of HIIT. 

HIIT has been demonstrated to cause adaptations that will improve anaerobic capacity (the ability to perform full effort activities such as maximum lift) even for highly trained individuals.[3] The mechanism via which HIIT seems to improve anaerobic tolerance is related to an increase in enzymes that burn glycogen, and an increase in ATP, improving the muscle’s ability to buffer byproducts of metabolism and an improvement in phosphocreatine recovery by up to 14%.[4]  HIIT also increases the ability to mobilize free fatty acids during a high intensity effort. 

It turns out that strength/power training produces similar adaptations as HIIT. In strength/power training the body adapts by increasing stores of ATP, and increasing the activity of creatine kinase, myokinase and enzymes used to burn glycogen.[5]  Indeed, weight training has been shown to have a cross over enhancement effect on anaerobic activities such as sprint cycling.  Likewise, bouts of short sprinting type exercise have a positive effect on strength training. In addition, HIIT improves cardiovascular condition. This makes HIIT a great tool for gaining endurance without interfering with strength or power development. Also, since the exercise duration is short, it is not likely to lead to muscle breakdown as a fuel source.  Furthermore, by boosting the bodies’ ability to oxidize free fatty acids, it increases the utilization of fat as a fuel both during exercise and during the rest of the day, which helps to improve lean muscle mass.  

The optimal HIIT level to achieve maximal improvement is still rather controversial.  A brief perusal of the literature will yield a wide variety of ideas about this.  Most of the studies have been done on runners. However, it is apparent that the better trained the athlete; the closer they need to run to their maximal effort in order to get the training benefit. Hence, training intensities of 50% of maximum output result in training improvements in untrained people.  While training intensities of 90% or more are required in the elite athlete.[6]   Another study looked at cyclists doing a variety of HIIT regimens and found significant benefits with work to rest ratios of 1:2 or with a rest period at 65 % of maximum heart rate.[7]  A study looking at cyclists noted optimal improvement with near maximal intensity effort done at 60% of the time to exhaustion with a 1:2 work to recovery ratio.  The recovery intensity was at 65% of maximum heart rate. 

Unfortunately, there really are not sufficient studies out there to reach a definitive conclusion on what works best for power/strength athletes. Thus, we must revert to using what we know in theory to come up with a rational approach. First, it must be recognized that there are three energy pathways at play in any exercise effort. There is phosphocreatine, anaerobic glycolysis and oxidation.  The first two are anaerobic (or occurring without the need for oxygen) and supply most of the energy for a full out effort such as a sprint or power lifting. However, really all three processes are in play at any one time, just in varying proportions. At the beginning of an all out exercise effort such as sprinting, the energy for the first 30-seconds or so will depend greatly on phosphocreatine. However, as time increases, anaerobic glycolysis becomes the more dominant energy system from about 30 seconds to 3 minutes. For times over 3 minutes, most of the fuel comes via oxidation.  In reality, the point where 50% of the energy comes from anaerobic processes and 50% from aerobic processes is at about 75 seconds.  You can get an idea of this from the following table.  

Estimates of anaerobic and aerobic energy contribution during selected periods of maximal exercise[8] 

Duration of exhaustive exercise (sec)

    %Anaerobic                                           %Aerobic

0-10                           94                                                        6

0-15                            88                                                        12

0-20                            82                                                        18

0-30                            73                                                        27

0-45                            63                                                        37

0-60                            55                                                        45

0-75                            49                                                        51

0-90                            44                                                        56

0-120                          37                                                        63

0-180                          27                                                        73

0-240                          21                                                        79

a Approximately °” 10% at the 95% prediction level  

So, for instance, if it is the phosphocreatine (PC) pathway that we want to improve, these ideas would help come up with a possible training schedule. To train the phospho creatine (PC) system, one might consider a full out effort (95 to 100%) that almost depletes the PC system, say for about 15 to 20 seconds.  Again, from the few studies that have been done, amping the intensity of the effort up to near maximal, but limiting the duration of the activity to 60% of the time to required to reach complete exhaustion. Subsequently, one should rest enough to allow the muscle to buffer lactic acid and to replenish creatine kinase stores (about 2 to 3 minutes).  At this level, the heart rate should not yet have reached baseline and should be in a low intensity aerobic range (maybe 65% of the maximum heart rate). However, if one recovers more quickly that this, then the rest period should be made a bit shorter. If one wants to train the anaerobic glycolysis system, performing a full effort activity for about 45 to 75 seconds at about 85 to 90% of full effort and having a relative rest period of about 2.5 to 3 minutes would seem reasonable.  Finally, to train the aerobic system, one would train at 30% to 40% of maximum output over 4 or more minutes with a relatively short rest period or a work to rest ratio of 1:1 or less. 

For a power lifter, it would seem that the system most likely to be helpful would be training the phospho creatine system.  Therefore, a program of 15 to 20 seconds of full out effort coupled with a rest period of 2 to 3 minutes would probably be appropriate.  

In summary, HIIT can be a very useful training technique, but the optimal program for bodybuilding/power athletes has not been fully determined.  Currently, it would make sense to rely on a program of nearly full intensity effort for about 15 to 20 seconds coupled with rest periods of from 2 to 3 minutes or with the heart rate dropping to about 65% of maximum, depending on the training level of the person.  Please keep in mind that this level of activity is subject to clearance from one’s physician and that untrained individuals can make progress at far lower intensities of effort. 

CG Perry, GJ Heigenhauser, A Bonen, LL Spriet  High-intensity aerobic interval training increases fat and carbohydrate metabolic capacities in human  skeletal muscle. Appl Physiol Nutr Metab (2008) 33: 1112-23. 

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