FATIGUE: GURPS, MAGIC, and SCIENCE

[hal]

Hello All,
Based upon another thread, a comment was made about mages may be able to avoid what amounts to a sedentary lifestyle penalty (unfit) simply by spell casting. That got me to thinking a little about how GURPS handles spell casting and made me wonder overall how things work in a default setting where "energy required" can be equated to the science of caloric expenditures...

Changes in muscles occur when the muscles are exercised. You can bulk up so as to build power, or you can train for endurance, in which your muscles have become used to working for long periods of time where production of byproducts of metabolism begin to occur.

"Muscle fatigue and burning during high intensity exercise result from an accumulation of intracellular metabolites such as inorganic phosphate and hydrogen ions that impair the contractile function of the muscle."

"How is ATP used in the Krebs cycle?
The Krebs cycle produces the CO2 that you breath out. This stage produces most of the energy ( 34 ATP molecules, compared to only 2 ATP for glycolysis and 2 ATP for Krebs cycle). The electron transport chain takes place in the mitochondria. This stage converts the NADH into ATP."

ATP is Adenosine Tri-Phosphate and ADP is Adenosine Di-Phosphate. Think of ATP is a high energy density battery and ADP as a lower state battery that has lost some of its energy and having an extra phosphate molecule that is no longer part of its structure...

Now, how would this relate to GURPS? A person who hikes for 3 hours at 4 mph on level ground, will utilize 3,000 calories. If fatigue loss from hiking for 3 hours unencumbered works out to be roughly 3 points, then each fatigue loss point is roughly equal to 1,000 calories of consumed energy. If a person expends more calories of energy than they consume in meals, they're going to lose weight. If they consume more calories than they utilize, they will eventually gain weight. Weight gain or loss can also occur when the body is not getting enough food and it stores what energy it can (fat) during times where ever calorie counts - that science is not something I'm all too aware of and someone else can probably spot the flaws in my explanation only too well (ie, take this with a grain of salt!).

That being said - what is exercise? How does one's muscles become either "bulked up" for explosive quick work, or become streamlined for long term endurance activity? Vagulely rememberd from my Biology classes of the late 1970's and early 1980's - muscles break down during use and repair during sleep. The form of repair is determined by the cause of the break down. Thus, weight training to bulk up is geared one way, while endurance style traiing is geared another.

So, what precisely is Magic doing to the body when it forces it to power a spell? Is it breaking down ATP to ADP, and that energy combines into roughly 1,000 calories per Fatigue point of a spell? Are the muscles contracting and expanding constantly and the ATP breaks down to ADP to provide the energy for the muscle contractions? Probably not.

Here is where I think that FIT and VERY FIT as advantages SHOULD work towards making energy expenditures for spell casting, cheaper. Because the body suffers from "Fatigue loss" and a man who spends 9 of his 10 fatigue walks at the same speed as if he had hiked for 9 hours straight - that the body is in fact, providing energy (Caloric energy) in the same fashion either way. If the Body was providing that energy from "Energy reserves: Magic only" and had no effect on the physical body, then that would seem to be a cause for saying that magical energy is not caloric energy. Why? Because a man who has 9 energy reserve and a fresh body, can cast a spell at 9 energy and still walk as if he had not expended any of his personal physical energy.

If a man casts a spell from a power stone and from his physical body, he is effectively using both forms of energy - caloric from his physical fatigue battery, and magical energy from his power stone.

It probably doesn't help that in the beginning, Fatigue was calculated off of Strength in GURPS 3e, and in GURPS 4e, is now calculated off of HT.

So, what are YOUR thoughts in this?

If a Mage routinely spends 8 fatigue per day, where each point of fatigue is worth roughly 1,000 calories - does said mage have to each sufficient amounts of hearty meals like a hard working man might have to? Using the AFTER THE END rules for long term fatigue, might a mage who uses more energy than he replenishes begin to suffer long term effects of not eating sufficient amounts of food for the work he does?

:)

[whswhs]

If you want to envision magic in cardiovascular terms, I'd look at two things.

First, a case can be made that magic is taking place in the brain, which is the symbol processing center of the human organism. The human brain is an energy hog, using 20% of basal metabolic energy. Maybe mages are having the brain firing really intensely, using much more than that. (Thought: You can spot a mage by their head getting hot, using Infravision or even laying on of hands. Perhaps exhaustion takes place when the brain gets overheated and unreliable.) There needn't be huge muscular effort; waving hands and chanting aren't athletically strenuous.

Second, I think that Fit and Very Fit can be defined primarily in terms of cardiac and respiratory function. Maybe what they do for mages is let the heart pump more blood into the brain, and keep the blood better oxygenated. That might be even more important than for athletic effort; the muscles can function anaerobically, but I don't think the brain is capable of that trick. Good blood flow may also help redistribute heat from the brain to the rest of the body.

[hal]

NICE! An interesting way to look at it.

But - this still leaves the issue of the body utilizing its natural ATP energies converted to ADP - and requiring a high caloric intake to make up for the energy that they're burning through.

If 3000 calories per day is required for an average sized adult individual who is working harder than most - then a mage who is casting magic off their body's energy rather than energy reserves (either natural within themselves, borrowed from their familiars or borrowed from power stones, or possibly stolen via spells) - then they need to replenish their batteries. This is where the Long term fatigue effects begin to occur. Why? If you expend too much energy and don't replenish it fast enough, how is that any different than starvation outright? Your body is just not getting enough food.

The real question then, is how to quantify it. ;)


Hmmmmm, my mind is pondering this for a bit to see if I can find a way to make it work. In theory, somewhere, there has to be data on soldiers who do a lot of marching and hard work over time, who end up losing weight as a consequence (just as there is data on how horses slowly starve during campaigns due to a lack of sufficient foodstuffs despite the extra demands for work placed on them). Somewhere we can equate 1 energy point with about 1,000 calories of energy being used, then figure out how much food is required to top off the body's reserves despite the heavy demands on it.

[WingedKagouti]

Fit and Very Fit were originally excluded from affecting fatigue spent on magic (and psionic abilities) in part to make the advantages "not mandatory" for optimized mages (and psis). And then mages were given Recover Energy to fuel their spells.

If you want to say that high levels of FP spendings on magic cause biological reactions similar to that of general physical exertion, you should let Recover Energy reverse that effect. As far as game mechanics go, you could treat it as starvation (B426) that can be handled either with food or through the use of Recover Energy.

[dcarson]

There were two books can't remember the author, published by Baen I think where you did burn your own energy to cast magic. Mages tended to look like sumo wrestlers. Hire one to do something major and you are paying for the time and food needed to get back to 300 pounds from skin and bones after casting the spell.

[hal]

Originally Posted by WingedKagouti

Fit and Very Fit were originally excluded from affecting fatigue spent on magic (and psionic abilities) in part to make the advantages "not mandatory" for optimized mages (and psis). And then mages were given Recover Energy to fuel their spells.

If you want to say that high levels of FP spendings on magic cause biological reactions similar to that of general physical exertion, you should let Recover Energy reverse that effect. As far as game mechanics go, you could treat it as starvation (B426) that can be handled either with food or through the use of Recover Energy.

Recover Energy being a spell, that's one thing. Flip side is - the natural part. ;)

How much energy can your body provide before it starts to have to deal with depletion? In GURPS, there is no such limit. Then again, no one ever really bothered to try to map real world energy use of the human body hiking for 3 miles at 4 mph against GURPS either. GURPS permits one to recover one's energetic levels after only a short rest. Now, what happens when you take someone who has never run a marathon, and force them to run a marathon? legend has it that it the original marathon runner promptly died at the end of delivering his message. In GURPS terms, he'd have to be at a point where he'd be at a death saving roll and then fail that death saving roll, something that doesn't happen until -HT values or worse. By the time you reach a point of 0 fatigue left, you have to roll each second to remain conscious - something that is statistically impossible in GURPS rules no?

In the end, it is an inquiry into how one WOULD use a "Switch" to the effect that constant spell casting depletes the body's natural energy reserves to the point that the spell caster is abnormally thin due to the intake of food is less than the outgo of energy. It might explain why Mages have to EAT a lot of food afterwards. Long Term Fatigue rules in AFTER THE END would be an interesting rule to try out - or not. ;)

It would also explain why mages - when given a choice, would prefer to receive energy from their apprentice, or use a powerstone or perhaps use paut or what have you.

[Plane]

Originally Posted by hal

Using the AFTER THE END rules for long term fatigue, might a mage who uses more energy than he replenishes begin to suffer long term effects of not eating sufficient amounts of food for the work he does?

I always figured Cole's "Action Points" in "Last Gasp" could be seen as ATP equivalents, whereas his approach to long-term fatigue (FP regenerates slower in the "Last Gasp" system) could be seen as Glycogen stories (circulating Glucose being somewhere in between) while long-term fat loss could probably be HP itself.

I always thought it might be interesting to assign some free "Energy Reserves" to represent other bodily systems, like the FP you lose via dehydration or starvation or lost sleep.

Basically to keep with the classic concept (these problems combine to cause problems) you would regenerate these pools via your basic overall FP.

Regeneration of those ERs could then be done by viewing the ability to eat/drink as forms of Leech (ER only) which target blueberry muffin HP and water elemental HP which you have imbibed, probably by a long-term Corrosive Attack as an Internal Advantage (stomach acid then intestinal absorbtion)

[whswhs]

Originally Posted by Plane

I always figured Cole's "Action Points" in "Last Gasp" could be seen as ATP equivalents, whereas his approach to long-term fatigue (FP regenerates slower in the "Last Gasp" system) could be seen as Glycogen stories (circulating Glucose being somewhere in between) while long-term fat loss could probably be HP itself.

If I had to pick one single process to represent lost hit points, it would be hypovolemic shock (and catastrophically falling blood pressure).

[Opellulo]

Just IMHO but tt seems a bit shallow to try to scientifically define what are the effect of magic on body without having first defined what magic is and how it works...

Yes it's pure speculation about fictional things but to me you are trying to paint a canvass without having first defined what colors are your going to use.

[Varyon]

If you want to equate 1 FP to 1000 kcal, then you'll need to do that across the board. A person who burns up 3 FP hiking needs to eat three meals (GURPS meals work out to between 1000 and 1200 kcal each, based on content and weight, although I think it lets you get away with around 800 kcal for one food item, maybe jerky) in addition to normal consumption needs for the day, as does a person who burns 3 FP on extra effort... or someone who fights for more than 10 seconds while at Medium Encumbrance (1 FP for fighting, +2 FP for being at Medium Encumbrance).

I suspect that's not really achievable for most campaigns, particularly those with a lot of combat.

Of course, I'm also curious where you're getting that 1000 kcal per hour of hiking value from. Using this online calculator, I'm getting an average (160 lb) person hiking for 180 minutes over level ground for 3 hours burning 1593 kcal, right around half your value. Giving them a 140 lb pack gets them to 2988 kcal... but at that point they're at 7xBL and thus Extra Heavy Encumbrance, which would mean they burn through 15 FP. Heck, being at Light Encumbrance, or between a 20 and 39 lb pack, burns less than 2000 kcal (x1.33 to energy expended), despite GURPS having this result in losing twice as much FP.