By James Smith
Sports are defined by movement and bioenergetic supply mechanisms provide the energy for muscle contraction.
The two primary bioenergetic domains (Anaerobic and Aerobic) are differentiated based upon the biochemical substrates which they metabolize in order to synthesize adenosine triphosphate (ATP) which is essential to facilitate muscle contraction.
Simply put, the human organism has two primary ways of synthesizing ATP — with and without oxygen.
To be taken literally, the (an)aerobic system conducts is operations void of oxygen. This system is subdivided into the anaerobic-alactic (no lactic acid) and anaerobic-lactic (with lactic acid) (or glycolytic reflective of the process of anaerobic glycolysis — the breakdown of glucose via the anaerobic machinery).
The anaerobic-alactic system is recognized as the short term system, or the ATP-CP system in reference to breakdown of creatine phosphate (CP) whose energy release couples with other processes specific to the re-synthesis of adenosine triphosphate (ATP). This system, regarding continuous movement, is responsible for the shortest duration and highest intensity muscular outputs.
The anaerobic-lactic system, the medium term system, signifies the process of anaerobic glycolysis. Glycolysis refers to the breakdown of glucose (sugar) and the subsequent energy release is one of the mechanisms associated with ATP synthesis. Lactic acid is one byproduct in the process of anaerobic glycolysis — hence the anaerobic-lactic system. In the context of continuous movement, this system is responsible for medium duration and relatively high intensity muscular output.
Here we see the biochemical difference between the anaerobic-alactic and anaerobic-lactic systems. Much of the literature that permeates the sports industry fails to make this distinction and, as a result, many coaches have been misled into thinking the anaerobic system, and as a result many sports, is solely linked to it’s anaerobic-lactic subdivision. One eventuality of the misdirection is the misappropriated volumization of lactic loading in the preparation of team sport athletes.
The aerobic system is constituted by three stages- glycolysis (aerobic), krebs cycle, and oxidative phosphorylation. Each stage yields ATP synthesis, with the last stage (oxidative phosphorylation) yielding the highest ATP output of the three. The aerobic system, or long term system, in the context of continuous movement, is responsible for mechanizing the longest duration/lowest intensity muscular outputs. The purpose of this article is limited to the discussion of the anaerobic system, however.
Important to note is that at no time is any single energy system responsible for muscle contraction. All systems are present at all times, the difference lying in their proportionality and contribution to the task at hand.
In terms of continuous movement, and the of the role of anaerobic energy supply in sport, it is useful to reference track and field events in order to illustrate the physiology of muscle contraction in a practical sense.
If one takes off running as fast as possible around a 400 m track they will invariably and eventually exhaust all three bioenergetic systems (anaerobic-alactic, anaerobic-lactic, aerobic); provided they are fit enough to continue running and experienced enough to economize their movement.
It is accepted that purely alactic efforts, in which the movement is generated with maximum intensity, are limited to less than 8 seconds of continuous action. In T&F sprinting, the fastest male sprinters will reach the 80 m mark in this amount time.
Continuous efforts, that are predominantly lactic, are agreed to begin after approximately 20 seconds of exertion at the highest attainable intensity relative to that time frame. In the literature, this may then extend out as far 30 seconds or more before the aerobic system begins to assume more and more of the lion’s share of proportionality. From this we see the lactic contribution to the 200 m, 300 m and 400 m events in track and field.
You’ll notice the gaps in time frames between the alactic and lactic bioenergetic contributions. It is here where further distinctions must be made between the energy systems.
Zhelyaskov and Dasheva, of the NSA in Sofia Bulgaria, expounded upon this topic in great detail in their text “Training and Adaptation in Sport”. The authors reference the power, capacity, and efficiency of each system.
In short, the power of each system reflects its peak intensity, the capacity reflects the total work output, and the efficiency is to be taken literally.
In this way, we may then fill in the gaps related primarily towards the power and capacity of each energy system:
- Anaerobic-alactic power — < 8 seconds
- Anaerobic-alactic capacity — up to 20 seconds
- Anaerobic-lactic power — 20 to 30 seconds
- Anaerobic-lactic capacity — up to 90 seconds
- Aerobic power — 90 sec to 2 min
- Aerobic capacity — > 3 min
It is critical to note, however, that each athlete, their genetic attributes, and method of preparation will have significant impact on the power and capacity of their bioenergetic development. In addition, the nature of the work performed must be taken into account as the number of muscles involved in the work and the dynamics of movement will have profound effects on the movement intensity.
From this set of guidelines we may then classify some of the senior track events as follows:
- 60 m sprint, 60 m hurdles — anaerobic-alactic power
- 100 m sprint, 100 m hurdles, 110 m hurdles — anaerobic- alactic power/anaerobic-alactic capacity
- 200 m sprint — anaerobic-alactic capacity/anaerobic-lactic power
- 400 m sprint, 400m hurdles — anaerobic-lactic capacity/aerobic power
- 800 m — aerobic power/aerobic capacity
In regards to continuous movement, in this case sprinting, it is understood that intensity must be reduced in order to extend the duration/distance of the effort. It is here where we may note the distinction between effort and intensity and the fact that the two must not be confused with one another.
In the sprints in track and field, the intensity is synonymous with velocity. In this way, the order of intensity of the senior outdoor sprint and middle/long distance track events is categorized as follows from highest to lowest intensity:
- 100 m
- 200 m
- 400 m
- 800 m
- 1000 m
- 1500 m
- 2,000 m
- 3,000 m
- 5,000 m
- 10,000 m
Effort, on the other hand, is a subjective process and typically associated with physiological stress (often considered as being synonymous with blood lactate concentrations). In this way, many would invert the order listed above in order to rank the events according to their grueling nature- though 400 m specialists would likely argue that their event is the breadwinner for masochists due to the perfect storm of lactic and aerobic contribution.
In the literature, the primary measure of lactic contribution is calculated according to the millimoles of blood lactate per liter of blood (mmol/l). The higher the concentration the more challenging and uncomfortable the effort becomes. It is here where the 400 m athlete holds a strong stake in the T&F pain argument as the blood lactate concentrations associated with the 400 m event are the highest in the track world.
While the continuous nature of track and field sprint and middle/long distance events make for useful practical representations of bioenergetic contribution in sport, one would be remiss to end the discussion there. From a developmental standpoint, as well as to acknowledge the bioenergetic nature of various other sports, it is essential to outline the bioenergetic implications of interval training.
In the continuous track events it is recognized that the sprinters/runners are moving as fast as possible with respect to the given distance. In an interval based endeavor, such as a variety of workouts and all combat and team sports, the movements are constituted by series of work and rest and the movement intensity can vary dramatically during even a very short duration interval. In this way, it is possible to perform aerobic interval workloads via repetitions of work as short as a few seconds.
Consider extensive tempo in which a 10 sec 100 m man would perform thousands of total meters of reps of 100 m in 14 seconds. After each rep he performs some calisthenics, takes a short rest of 30-40 seconds then performs another run. The intensity of his runs are less than 75%, the recoveries between runs are short yet sufficient, and as a result, provided he’s fit, the work remains sub-maximal and aerobic.
Duration and intensity are the two primary factors often discussed when determining the bioenergetic character of motion. Similar, however, to how the anaerobic system must not be narrowly thought of as only the anaerobic-lactic system, we must broaden our frame of bioenergetic consideration to include topics such as the number and size of the muscles involved in the work, movement dynamics, frequency and density.
Consider the following examples relative to a sub-10 sec 100 m sprinter:
- a maximum intensity 6 second sprint is a purely alactic endeavor
- two maximum intensity 6 second sprints separated by 10 minutes of rest are purely alactic endeavors
- a maximum intensity set of 4 x 6 second sprints, each one separated by 10 minutes of rest, will remain a purely alactic endeavor
- a maximum intensity 6 second sprint followed by 10 seconds of rest will vastly reduce the intensity of the second repetition (regardless of the sprinter’s effort) and blood lactate concentrations will climb
- a maximum intensity 6 second sprint followed by a series of three more 6 second sprints (in which the sprinter must sprint as fast as possible), each one separated by 10 seconds, will result in phenomenally high blood lactate concentrations
From this example we see that the period of time separating the work bouts has tremendous implications on the bioenergetic character of the activity. The frequency is determined by the duration of rest between repetitions and the density is characterized by the total amount of work performed per unit of time.
On one end we have a series of four very high intensity 6 second sprints and the bioenergetic stress is purely alactic resultant of the sprinter taking 10minutes to recover between each one. In this way, the frequency is low and so is the density. On the other, we have a series of 4 x 6 sec sprints that are separated by only 10 seconds of rest. In this example, regardless of how much effort the sprinter exerts, his intensity will decrease sharply from one rep to the next; meanwhile, his blood lactate concentrates will dramatically escalate. In addition, the frequency as well as density are dramatically increased (4 x 6 sec with 10 sec rest between reps versus 4 x 6 sec with 10 min rest between reps).
The number and size of muscles involved in the sprint action are considerable and the largest muscles (gluteals and thighs) in the body are directly involved in the work. Further, the movement dynamics are such that a sub-10 second sprinter will incur nearly 5 times his bodyweight during each ground contact around the point in which he reaches maximum velocity. It is then logical to presume that at 6seconds of maximum intensity sprinting he would be very close to reaching maximum velocity and +4.5 x bodyweight at ground impact.
In the alactic version we have maximum intensity, minimal frequency and density, and in the lactic version we have moderate intensity (despite maximal effort), high frequency and high density.
What happens if we have the same sub-10 second 100 m sprinter replace his 6 second sprints with 6 seconds of wiggling his fingers? Even in the case of 4 x 6 sec with 10 sec rest between reps the rate of blood lactate accumulation would be fantastically slower- and possibly remain low enough to be alactic. The reason for this is because the size of muscles involved in the work, as well as the number, is dramatically lower and the dynamics of finger wiggling are far lower in intensity in comparison to sprinting.
When making bioenergetic determinations it is critical to account for the following factors:
- number and size of the muscles involved in the work
- the dynamics of movement
This set of examples makes clear the multitude of movement (sets x repetitions) x series and the rest intervals separating bouts of work which allow for the full spectrum of bioenergetic contribution.
Reference the following table (based upon the work and personal correspondence with Yuri Verkhoshansky, Vladimir Issurin, and Victor Seluyanov) in order to enhance the anaerobic alactic and anaerobic lactic preparation of athletes with respect to the diagnostic assessment of their sport. Taken from my book Applied Sprint Training.
|Type of Training||Training Intensity||Duration of Set||Rest Between Sets||Number of Sets|
|Anaerobic alactic Power||Maximum||< 6 sec||2-5min||5-6|
|Anaerobic alactic Capacity||Maximum||7-10sec||30s-1.5min||10-12|
|Anaerobic glycolytic Power||High||20-30sec||6-10min||3-4|
|Anaerobic glycolytic Capacity||High||40-90sec||5-6min||10-15|
Please share this article so others may benefit.