Segugio Unified Theory of Cardio for Athletes
A Word on Intensity
It is well established that substrate utilization, though always mixed, is determined primarily by intensity of expenditure. As intensity decreases, B-oxidation (%) increases. As intensity increases, glycolysis (as well as protein breakdown, ketone production, and activation of the phosphagen system) increases. Intensity is negatively correlated with efficiency, that is, fewer units of energy are produced from an equal amount of substrate for equal work. This necessarily “wasteful” practice is one of the reasons that anaerobic (compared to aerobic) exercise results in significantly higher total caloric expenditure. This has also become the basis of many different cardio protocols, as “total expenditure vs. total consumption” has become a popular (but misinformed) line of reasoning in the fitness world.
There are many other factors to consider in selecting the proper exercise intensity for your goals. Anaerobic exercise results in greater post-exercise oxygen consumption, which denotes a [usually insignificant] boost in metabolic activity for several hours afterwards. Despite the inefficient taxing of non-oxidative systems, anaerobic work generally results in more total B-oxidation (though less as a proportion) than an equal quantity of aerobic work. Anaerobic work has drawbacks in that it places greater stress on the CNS, endocrine system, and soft tissues. The immediate and systemic effects of cardiovascular training require thorough analysis, as these adaptations define training. There are, of course, many significant adaptations I do not explicitly mention, along with those that are not yet entirely understood. The following effects are what I believe most relevant to training.
Improved circulation and removal of metabolic wastes
Small Increase in AMPK activation
Increased total expenditure
Increased post-exercise oxygen consumption
Large Increase in AMPK activation
Increased GLUT-4 translocation
Increased mitochondrial density across all muscle fiber types
Increased angiogenesis (increased capillary density and nutrient delivery)
Increased AMPK concentrations in skeletal muscle
Increased GLUT-4 concentrations in skeletal muscle
Increased oxidative enzyme concentrations
Decreased resting energy expenditure
Pro-oxidative shift in muscle fiber composition (IIX->IIB->IIA->I)
Increased glycogen storage capacity
Improved lactate threshold (work required to induce contractile failure)
Improved motor unit recruitment
Improved mineral retention (calcium, sodium, potassium)
Increased glycolytic enzyme concentrations
Decreased resting energy expenditure
Pro-glycolytic shift in muscle fiber composition (I->IIA->IIB->IIX)
Notice that the body adapts through both oppositional and complementary pathways. What we perceive as Specialization is really just selective activation/avoidance of different signaling cascades. The most specialized athletes (ultramarathon runners, Olympic lifters) would suffer a performance decrement if they did not deliberately avoid certain stimuli. It is not to the benefit of the former to hold onto heavy and inefficient glycolytic muscle fibers, just as it is not to the benefit of the latter to hold onto inactive oxidative muscle fibers. Most other athletes, however, fall on the spectrum between the two extremes, and would benefit from varying amounts of both types of training.
Effects of Specialization
The last two items (colored red) in each Systemic Effects category are the products of prolonged and intense specialization. Their deliberate separation is intended to highlight two important issues.
1. Resting energy expenditure (or basal metabolic rate, if you prefer) is decreased at either extreme. Type I fibers are energy efficient by definition, and type IIX fibers have a great deal of surface area with relatively few mitochondria. The IIA/B (slow/fast glycolytic) fibers are least energy efficient, and most versatile. Something to consider if you like food.
2. Shift in muscle fiber composition is very very very very very slow. Most humans have roughly the same "default" fiber type scheme based on our physiology. Calves and stability muscles tend to be Type I dominant, Hamstrings and Triceps (for sprinting and pushing) tend to be Type II dominant. Though there is much fear in the strength community concerning light weights and cardiovascular training, it is entirely unfounded. Appreciable aerobic shifts in fiber composition are seen mainly in the quadriceps of distance runners, and the shoulders of marksmen. Anyone not applying a low intensity stimulus for several hours on a daily basis is extremely unlikely to downgrade their IIA fibers.
Regardless of one’s psychological objectives, the physiology of the body is interested only in energy efficiency and homeostasis. When an external stimulus is applied, there is an immediate reaction. Repeated application causes adaptation (though not always beneficial). On a hot day, your immediate reaction is to sweat and increase respiration. After a few weeks of brutally hot weather, you might feel spry and euphoric on a slightly less hot day, because your degree of adaptation (Conditioning) is greater than the applied stress. When the stressor no longer exists, your body will de-condition itself, as homeostasis is its sole objective in the absence of orders. The body is fairly proficient at short-term adaptation, as external stimuli may be a sign of danger. For instance, survival-minded people are able to manipulate sodium balance through controlled water intake in just a few days.
Short-term adaptations are generally patchwork solutions which can be easily undone as the environment changes. When someone undertakes weight training for several weeks, they may notice an increase in muscle size and density, due to increased glycogen storage and [corresponding] water retention. Though they would almost certainly like to believe their weight gain to reflect newly acquired tissue, it would be horrendously inefficient for the body to adapt so quickly. To build and then break down 10-15 pounds of tissue on a whim would lead to rhabdomyolisis every time we decided to climb a stair.
Evidence of short-term adaptation can often be tracked with reactionary hormone/enzyme level fluctuations in plasma. Sugar consumption tends to increase insulin output, as protein consumption tends to increase glucagon. Fasting stimulates PDK and inhibits PDP, just as feeding stimulates PDP and inhibits PDK. A resistance training session will increase muscle insulin sensitivity and GLUT-4 transcription for approximately 48 hours. Localized IGF-1 expression may last only a few minutes, and mineral balance adjustments may last a few days. The common traits among these adaptations are transience (the response is limited by the stimulus and/or the body’s systems) and reversibility (the response is connected to a biofeedback system).
Long-Term [Systemic] Adaptations involve a restructuring of tissues to more efficiently accommodate frequently applied acute stimulus. Because structural adaptations are metabolically expensive, the body must be subjected to stress sufficient to “convince” it that future energy efficiency is worth the upgrade cost.
Month 1: Workout A (200 cal base expenditure) x 30 days = 6,000 cal expenditure
Month 2: Workout A (200 cal base expenditure) / 1.15 (efficiency factor) x 30 days + 1,000 cal adaptive cost = 6,217 cal expenditure
Month 3: Workout A (200 cal base expenditure)/ 1.3 (efficiency factor) x 30 days + 1,000 cal adaptive cost = 5,615 cal expenditure
In this situation it is clearly visible that despite the 2,000 calorie “investment”, total expenditure is less than what it would have been with no adaptation (17,832 vs. 18,000).
Though systemic adaptations result in fewer calories burned for identical work on a perpetually progressive scale, the threshold on PER (Perceived Rate of Exertion) rises at a comparable rate. A sedentary person may inefficiently burn 200 calories by running a mile, and an elite marathoner may efficiently burn 80 calories for the same mile, but it is much easier for the latter to run three, than for the former to run one.
Synergy and Priming
An observant reader will already have gathered that several anaerobic short and aerobic long term adaptations are related, and could be applied in tandem to produce greater (versatile conditioning) results than strict adherence to one style of training.
Priming is defined as ancillary preparation for increased performance in a defined task. Football teams tend to travel to Denver a few days in advance, so that they can better adjust to the oxygen content of the air. Fighters may use a rolling pin to destroy nerves in their shins. A sprinter may perform a certain sequence of calisthenics and stretches prior to every race.
Priming is interesting in that it covers a broad spectrum from ritualistic anxiety reduction (carrying a lucky trinket), to unintentional versatility (an athlete who excels at one sport may be surprisingly adept at another, despite never having played), to synergistic adaptation.
Contrary to the current trends and fads in the fitness community, and irrelevant short-term studies on specialized populations (I’m sorry that certain exercises didn’t increase bone density markers in elderly women undergoing chemotherapy, but that’s not my target demographic), long-term aerobic conditioning leads to tangible physical performance improvements in almost every context.
Anaerobic Work in an Aerobically Conditioned State
It is in the interest of nearly every athlete, particularly strength athletes, to pursue aerobic fitness, for the reasons outlined below.
1. Enhanced Recovery (immediate). Increased circulation expedites the removal of metabolic wastes, and expedites nutrient transport to damaged tissues.
2. Enhanced Recovery (long term). Angiogenesis leads to increased capillary density and enhanced nutrient transport, even when resting.
3. Easier Fat Loss. Thinking about activating some AMPK with a bout of anaerobic work? There's a lot more to activate if you're conditioned.
4. Preferential Glycogen Loading. It's generally in your interest that your muscles express more GLUT-4 than your adipocytes.
5. Heart Health. I have nothing but admiration and respect for gigantic people who lift outrageous amounts of weight, and I would never suggest refraining from the decadent side of powerlifting for non-athletic concerns (those are none of my business). It's important to to keep the heart well prepared to efficiently move blood around a 400 pound body, especially during prolonged exertion. A lift missed due to vertigo is still a missed lift.
Cardio plans require a great deal of trial and error, because there is really no way to accurately gauge mitochondrial density and efficiency. Some are genetically predisposed towards aerobic efficiency, some are genetically predisposed towards high glycogen storage. Genes, environment, food, and exercise all play extensive roles in how well we adapt.
Most people don't have the means to conduct enzyme tests during cardio, so our starting point should reflect typically observed responses. Further calibration is done on an individualized basis, though a [real] trainer is very highly recommended. There is no amount of expertise that can replace another set of trained eyes.
Fasted AM Cardio
The popular misconception is that fasted AM cardio is made effective by the presence of ketones or the absence of glycogen. Though both of those conditions would lead to greater fat utilization, they are not specific to a fasted state. One could produce ketones at any time of day. Similarly, one can be depleted of glycogen at any time of day.
The efficacy of fasted AM cardio comes from the pro-oxidative enzymes released during fasting, namely the expression of [PDK] Pyruvate Dehydrogenase Kinase and [LPL] Lipoprotein Lipase. These enzymes, left undisturbed, also (partially) inhibit the production of other substrate-specific enzymes. Because substrate utilization is mostly dependent on intensity, sleep is the most proportionately oxidative activity one can undertake. These two factors create an environment where near 90% of expenditure is fatty acid oxidation.
Split Session Cardio
Every bout of cardio separated by enough rest will incur an activation cost, as well as an increase in post-exercise oxygen consumption. Activation of the sympathetic nervous system results in increased AMPK and glucagon expression. The latter is particularly important during strict dieting, where insulin spikes cause cravings of unfathomable severity. Split Session Cardio is also of benefit to athletes who are required to train at high intensity, allowing partial restoration of glycogen and phosphagen.
This is also made more effective by glycogen depletion and presence of ketones, but, just as with AM Cardio, that's not really its defining mechanism of action. Weight training increases AMPK, IGF-1, and Growth Hormone production. A low insulin environment allows the GH free reign to mobilize fat stores. The IGF-1 expression is local to the trained muscles, and has nothing to do with plasma IGF-1, which is decreased by aerobic exercise. It's also important to note that, assuming adequate nutrition, there is very little risk of protein degradation. Muscles begin repairing themselves immediately; they don't disintegrate in 30 minutes, due to the absence of your post-workout shake, as supplement companies would have you believe. The acute response to muscle damage is local. No matter what you decide to do after you lift, your muscles will be repairing themselves with available resources. Nutrient sensitivity is enhanced for 48 hours. You can activate MTOR 16 times before your next training session. Do your cardio.
Consideration: Fasted Sustained vs. Split Session
The increased rate of B-oxidation from fasted (10-14hr) morning cardio makes it ideal for the cutting athlete. Because substrate systems shift perpetually towards B-oxidation as duration increases, it would make sense to do one prolonged AM cardio session for maximal fat loss. Those with athletic considerations, however, should be wary of protein breakdown, which also increases over time, due to the steady depletion of glycogen stores. Split sessions offer the advantage of a second activation cost; the thermic effect of the body’s shift into a prepared aerobic state. Split sessions also allow partial restoration of glycogen stores, which would result in less protein breakdown (via greater glycolysis), given identical expenditure. A cardio plan designed for maximum efficiency should take these variables into consideration.
AM Cardio: (450 cal base expenditure) (F) (AC) (+)Modified: (D)
PM Cardio: (450 cal base expenditure) (AC) (+)Modified: (D)
Split Session: (225 cal base expendtiture) (F) (AC) + (225 cal base expenditure) (AC)
(F) – Fasted State, increases total fatty acid oxidation
(AC) – Activation Cost, increases total energy expenditure (substrate varies with availability)
(D) – Duration, increases % of total energy expended via B-oxidation
Though B-oxidation will proceed practically undisturbed for the duration of your fast, there are retaliatory mechanism which activate at around the 12 hour mark, and increase dramatically by the 18 hour mark. The most significant of these are the buildup of enzymes for de novo lipogenesis, and increased insulin receptivity of adipocytes.
Training beyond one's capacity can result in negative CNS effects. Fatigue, irritability, and extreme hunger may result from a very long training session. Dividing the workload between two sessions would have resulted in roughly the same benefits, and posed less risk of unintended effects.
Sport-specific training has a separate set of protocols. The biochemistry is the same, but attenuation procedures and training goals are different. If someone is building endurance for 30-40 mile hikes, they would very clearly benefit from prolonged training sessions, and probably don't need to be concerned with fasting or intra-workout calorie restriction. This guide is primarily for strength and physique athletes.
The Segugio Cardio Template
This is a basic progression scheme that I've found effective for increasing aerobic workload without peripheral effects. An untrained person would start at 30 minutes daily, adding 10 minutes every week, to be done in a single session, up to 80 minutes. The next week's 90 minutes would be split 45/45. The following three weeks would add 10 minutes to the first session only (75/45). Every week that follows adds 10 minutes to every morning session, and 5 minutes to every evening session: 85/50, 95/55, 105/60, 115/65, 125/70, 135/75. It is limited at 3.5 hours, because anyone requiring longer duration is likely training for specific endurance adaptations.
The intensity for all session is low to medium. Because high intensity work taxes the CNS, it should be planned separately, and given the same consideration as any other form of anaerobic work.
To be aerobically conditioned is to be metabolically primed for success. One would, in fact, be at a severe disadvantage by not being adequately conditioned, as they are limiting their training efficacy and capacity for recovery. There has been a dramatic shift in exercise theory over the past decade, and it is reflected (and perpetuated) by out of shape "athletes" suddenly finding the training programs and diets of years past to be ineffective.
Many trainers, bereft of actual knowledge or experience, are die-hard proponents of the newest or trendiest training style. Visible progress has been replaced by unwarranted self-importance. You may notice that "trainers" in your gym are identifiable only by their uniforms. You may notice obese or naive clients who "train" for years under the guidance of these idiots, and remain obese and naive, but pick up an attitude along the way. Why is this?
1. Physical adaptations require frequent stimulus over very long periods of time.
2. People want immediate results.
3. There is no way to get immediate results. Options:
4a. Tell people the inconvenient truth, suggest setting long-term goals.
4b. Promise immediate results, set arbitrary progress markers, pretend that they are all being met. This is actually what Mussolini's General Staff did for most of the 1930s. Worked out well for them, I've heard.
Because it's not enough to want immediate results, people also want convenient workouts. They never have "time". The fitness industry has always made money from convenience scams, but this sort of nonsense has worked its way into mainstream fitness culture. Most trainers in the 90s would have laughed at "8 minute abs" or "the thighmaster", but today, there is hardly anyone who doesn't swear by bosu balls, crossfit, or functional training. The goals of "lose weight", "gain muscle", "get stronger", "get faster" are in demand, just as they were in times past, but arbitrary progress markers give insecure people self-esteem, which is really why they were interested in fitness in the first place.
It's not unproductive, it's counterproductive. Contemporary program design is centered around bypassing the first five years of training, with the primary goal of a session being that people brag to their equally ignorant friends. To this end, you will see people who have never lifted a barbell attempting broom handle snatches, pushing a weighted sled, or doing curls on a bosu ball. Cardio protocol (in the rare event that it exists) is always HIIT. Always. Though it's the least effective form of exercise for an untrained person, it has two very important marketing advantages:
1. It doesn't take very long.
2. Shortness of breath and profuse sweating are misinterpreted as accomplishments
The disgusting state of affairs in the fitness world is fueled by society's self-deluded and hubristic nature. The same statement could have probably been made at any time in history, but this is the first time that the nucleus of the fitness world is comprised of baseless drivel. In the era of unlimited information, we've become too self-absorbed to learn.