Does it take more energy to go downstairs than upstairs?

Cecil's Columns/Staff Reports
1

I just found this website today, and there’s some very interesting information here. One thing I do have to comment on, although I’m sure someone has already mentioned it: there are two types of actions your muscles can make–concentric and eccentric. A concentric movement is one where you use your muscle to move a weight e.g. pushing the bar away from your chest in the benchpress or pulling a weight toward your chest in a barbell row. An eccentric movement is one in which you use your muscles to resist a motion e.g. lowering the bar to your chest in a benchpress. Eccentric movements cause the build-up of lactic acid in your muscles, which is what causes soreness. Since walking down stairs is a primarily eccentric movement, it would cause more soreness than walking up stairs, which is where someone would get the idea that wlaking down staris requires more energy.

Link to the Mailbag Item inserted by CKDextHavn, Board Moderator: http://www.straightdope.com/mailbag/mdown.html

[Note: This message has been edited by CKDextHavn]

2

Actually, eccentric motions cause soreness for another reason. If you can, imagine your muscle fibers have a series of “hooks”. These hooks (upon muscle contraction) grab, pull, and move to the next “hole”. This is actually a chemical action, but I’m not going to get into it here. During a concentric contraction, these hooks are climbing in the direction they were meant too.(since muscles can only contract one way) During relaxation phase, these hooks are withdrawn. If you do an eccentric contraction instead of relaxing, these hooks are grabbing and trying to pull up, however, they are moving the wrong way. This tearing motion is what causes the soreness. Lactic acid will build up during any type of muscle movement.
I can get the chemical process for you, but I thought I would explain it like it was taught to me.

3

Roksez: The hook and hole analogy is utter nonsense. Our muscles are arranged in pairs so that what one muscle cannot accomplish by contraction, another one can. "There is no “reverse gear,” so to speak. Anaerobic activity (operating oxygen-starved) and the build up of waste products in the muscle cells is what causes the “burn” (and the later soreness) that signifies the tissue damage that body-builders so crave. You gotta destroy some to get bigger, better ones.

The walking downstairs vs. upstairs is a matter of which muscle group you’re using.
Our climbing muscles have been fighting gravity for eons, and are correspondingly bigger and use more oxygen than their coasting-downhill counterparts. Oxygen consumption is a very accurate gauge of how much work a muscle is doing, and anyone who has hiked uphill one day and down the next can tell you, uphill requires more oxygen and downhill cause supreme agony in muscles unused to such nonsense.

4

Ok simple test to show what I’m talking about. Grab anything in your hand, and do a bicep curl. Now slowly lower it back down, letting it fall naturally, but with some resistance. Your tricep muscle is not contracting, your bicep muscle is. It is resisting the downward motion. It is contracting, but it is moving “backward”. This is taught as fact in my human kinesiology book, which I will dig out and get some exact quotes from. Perhaps you have a source for your information??

5

The eccentric motion does cause more soreness, not from oxygen depletion, but because of the method I described earlier. Unless the body of knowledge on this subject has changed in the last 2 years, I can assure you I am correct. If you doubt me, I will contact my professors to see if I have missed something, but my major is fitness/exercise physiology. I would hope I am not paying to be taught “nonsense”. Also, the “hook” thing is an analogy, as I said. It is actually a chemical reaction, which produces a ratcheting effect in the muscle fibers. These only connect in one direction, thus when you do an eccentric contraction (not a relaxion) you tear more of these fibers.

6

Yes, I understand what you mean by “eccentric” and “concentric,” although I have never heard these words used to describe muscle movements, and they really don’t make much sense when used as such. I guess the idea is that an “eccentric” muscle movement is one that goes against the “normal, accepted pattern?” (I cannot fathom how “concentric” figures into this. The whole thing sounds like a bunch of body-builder hooey). Anyway, it makes no difference, the muscle is contracting in the same manner - muscle cells move our body parts by making themselves shorter and fatter, regardless of which direction they are moving or whether they are actively or passively effecting movement. I cannot imagine where this idea of a “ratchet” arrangement came from, or maybe I don’t understand why you are using a mechanical analogy for what you say is a chemical process. I don’t understand how a chemical process can be responsible for the mechanical damage (“tearing”?) you describe. Or are you saying the muscle fibers somehow “let go” of each other and “reattach” in a different position? This I never heard.

Until you can provide me with some physiological basis for your claim - a reverse Krebs cycle, say - I’ll stick to Human Anatomy & Physiology 101 and stand by my original statement.

7

Ok, found the book,(actually my anatomy, this is not as detailed, but I digress). Here goes the technical explanation, and this will take awhile.
First, the structure and organization of a muscle.
1 Muscles are made up of cells known as muscle fibers, which are long cylandrical shapes up to 1 foot long.(Picture a fibreoptic phone line).
2 Each cell is further made up of myofibrils. Myofybrils are composed of units called sarcomeres, which lie end to end. (Again, fibreoptic phone line)
3 Myofibrils are composed of sarcomeres, stacked end to end. Sarcomeres are the contractile units of a muscle.
4 Sarcomeres are composed of two types of myofilaments called (this is real technical here) the thick one and the thin one. The thin one is composed of actin molecules, the thick one of myosin molecules. These filaments overlap, and when the actin molecules are slid past the myosin, contraction results.
Ok, now for the actual contraction.
On each myosin filament, the are myosin heads(which look somewhat like hooks). On each actin filament, there are binding sites, each covered with troponin(negatively charged)
When an impulse is sent to contract a muscle, positive calcium ions are released, which attach to the troponin, and pull it away from the binding sites on the actin.
Once the sites are exposed, the following occurs.
1 The active myosin heads are attracted to the exposed binding sites, and cross bridging occurs.
2 As the head attaches, it bends, pulling the actin filament toward the center of the sarcomere. At this point, adenosine triphosphate(ATP) binds to the head, and returns it to its original position. The actin filament has now been slid slightly towards the center of the sarcomere.
3 The head is now ready for another “step” and it binds to the next site on the filament. Keep in mind there are many, many heads, and some are always in contact with the actin filament. If this were not the case, the filament would simply slide back to its original position.
Now picture all these heads, attaching, bending, releasing, grabbing again, attachin, etc. This is a muscle contraction. Usually, one “pull” generates a shortening of about 1% of the muscles length. Some muscles can perform 30-35% shortening, so many of these cycles are repeated.
side notes:
1 Since dying cells cannot exclude calcium ions, they promote the cross bridging of dead muscle tissue. These contractions are more commonly known as rigor mortis.
2 When ATP is relatively depleted, the heads cannot detach and move on. The muscle is in a continual state of stationary contraction. Writer’s cramp is an example of this.
3 There are three types of contractions:
a)isotonic (regular contraction, the vertical lift in a bench press)
b)isometric (contraction, no movement. Push on a wall, your muscle contracts, but does not move)
c)eccentric (contraction with reverse movement. When you bring the bar back down on a bicep curl, you are not pulling it with your triceps, you are contracting your biceps in a way that you slowly let it down. A true eccentric workout is one in which you cannot physically lift the weight. Someone else helps you lift it, you let it fall as slowly as possible.

All this brings us to why eccentric contractions cause more soreness. You are correct in stating that muscles only contract one direction. The heads cannot contract , release, and move backwards. When you do an eccentric motion, the heads are attaching and trying to ratcht to the next site. However, the muscle is lengthening. You are actually tearing the heads away from the binding sites. This causes the extra soreness associated with doing an eccentric workout.
We are taught to use simple explanations so that we can pass them on to people we are doing rehab or workout programs for. Everyone knows how sore you get after the first few times you work out, and there can be several reasons for the soreness. If your job is to make sure this person continues to follow their program, you have to explain the reasons in everyday language.
Thus, the “hook, pull, and ratchet” analogy. I’ll try to recall more of the chemical reaction, it involves positive and negative ions, and the signal from the neural net that says “contract”
And yes, it is possible to get sore walking down a hill, as well as up. But who wants to climb a hill and wait two days, see how sore you are, recover, and walk down, and see how sore you are, and compare. If you are out of shape, you’re probably going to get sore.

8

forgot this as well–
Your krebs cycle comment is on the right track, it is the cycle which provides the energy for the above movement. The krebs cycle produces ATP, which is necessary for the above to happen. It is actually the first step in all of this.

9

I stand by my original explanation. I’ve attached an abstract from medline that says
(a) Lactic acid is a factor contributing to muscle soreness, and (b)DOMS is biased toward eccentric muscle actions. Sorry it took me so long to respond, especially since I started the thread, but I had some quals. occupying my time.
1.
Miles, MP; Clarkson, PM. Exercise-induced muscle pain, soreness, and cramps.
Journal of Sports Medicine and Physical Fitness, 1994 Sep, 34(3):203-16. (UI: 95131528)
Language: English; Pub type: JOURNAL ARTICLE; REVIEW; REVIEW, TUTORIAL
Abstract: The three types of pain related to exercise are 1) pain experienced during or immediately following exercise, 2) delayed onset muscle soreness,
and 3) pain induced by muscle cramps. Each is characterized by a different time course and different etiology. Pain perceived during exercise is considered to
result from a combination of factors including acids, ions, proteins, and hormones. Although it is commonly believed that lactic acid is responsible for this
pain, evidence suggests that it is not the only factor. However, no single factor has ever been identified. Delayed onset muscle soreness develops 24-48
hours after strenuous exercise biased toward eccentric (muscle lengthening) muscle actions or strenuous endurance events like a marathon. Soreness is
accompanied by a prolonged strength loss, a reduced range of motion, and elevated levels of creatine kinase in the blood. These are taken as indirect
indicators of muscle damage, and biopsy analysis has documented damage to the contractile elements. The exact cause of the soreness response is not
known but thought to involve an inflammatory reaction to the damage. Muscle cramps are sudden, intense, electrically active contractions elicited by motor
neuron hyperexcitability. Although it is commonly assumed that cramps during exercise are the result of fluid electrolyte imbalance induced by sweating, two
studies have not supported this. Moreover, participants in occupations that require chronic use of a muscle but do not elicit profuse sweating, such as
musicians, often experience cramps. Fluid electrolyte imbalance may cause cramps if there is profuse prolonged sweating such as that found in working in a
hot environment. Thus, despite the common occurrence of pain associated with exercise, the exact cause of these pains remains a mystery.

10

I totally agree with you; the pursuit of a cure for DOMS is of great concern in my profession-to be. You can either decide to go easy when you first work out, and gradually build your intensity, or just blow it all out at once and be sore for a few days. After taking a break from working out, I usually will work out twice at low weight, medium rep, then start working out hard. If I still get DOMS, I just so low weight/high reps for a few days til it’s gone. Potassium and drinking water seem to help some people offset the effects.

11

Not for nothing, kids,but I drink Diet Tonic Water. The Quinine therein not only keeps me from getting wicked leg cramps, but keeps down the Malaria.

More biking, less worrying !!

Typer

12

I dunno how the science/medicine works, but it definitely takes me more energy to go up than go down. FWIW, though, you are more likely to hurt yourself going down.

13

Ok, Rok - that explanation makes sense. What threw me was the mechanical analogy for chemical process. The “tearing” you cite is chemical, not mechanical. (I still don’t know how this equates to “tissue damage”).

I’ll stand by every single statement in my original post with the exception of the first sentence.

14

Sorry, folks, but all this scientific info is quite unnecessary. I know from daily personal experience (not to mention common sense) that it takes more energy to go up stairs than down. Jeeeeeezzzz…gimme a break!

15

I think the original question should have been: Does walking downstairs result in more soreness than walking upstairs. It obvioulsy does not take more energy. I can answer the following question: will a workout consisting of nothing but eccentric contractions result in more soreness that a concentric workout. Assuming equal levels of intensity, yes.

16

Geez, you guys obviously aren’t physicists. And for that matter you weren’t paying much attention in high school. Not counting any special forces from the human body (like one muscle having more friction than another) it takes exactly the same amount of energy to go upstairs as to go down.

When you push a ball down the stairs the energy goes into motion and the ball smashes into something. People (well at least me) don’t randomly collide with walls after going down the stairs. You start going down the stairs at a nice pace and the length of the staircase doesn’t affect the speed you leave it at. Therefore you have absorbed the energy (mgh whether going up or down).

In a ball all the potential energy goes into speed, and lacking any survival instinct, it doesn’t absorb it.

17

I think that is the most ridiculous application of physics I have ever seen. How does the ball go upstairs??? If your application is correct, then slowing a 100 pound weight as it falls takes as much energy as raising it. Does anyone believe this? I think you are saying if it takes X amt. of energy to go from pt.A to pt.B, then it takes the same amount to go from B to A. Which is fine if you don’t account for gravity. When you climb stairs, you are doing concentric muscle contractions of (mainly) the gastocnemius muscle. When you descend, you are doing eccentric contractions of the gastrocnemius muscle. Concentric contractions use more energy than eccentric contractions to control the same amount of weight. However, due to their nature, eccentric contractions cause more soreness. For this reason, you lift higher weights doing an eccentric workout, and will be sorer, but you can do more reps, and actually need to, to use the same amount of energy . (an eccentric workout would be one in which if you were doing bench press, someone else lifts the weight up, and then you slowly lower it back down.)

18

I think that is the most ridiculous aplication of physics I have ever seen. If your application is correct, then slowing a 100 pound weight as it falls takes as much energy as raising it. Does anyone believe this?

Boy one would have the knowledge of science had advanced since the middle ages.
First of all I specifically said that I wasn’t including any special forces from the human body. So we’re assuming that the human body is frictionless here. Besides the original question was what takes more energy not which makes you more sore.

As for your question: Obviously it does! If it didn’t where would all the energy go? You raise a brick 1 meter and then lower it back down and it releases less energy, so where does the energy go? By your logic the universe would be doomed to a quick dissappearance from all this “leaking” energy.

Look, simple physics. Potential energy is mgh. You raise a 1 kg mass 1 meter and you use 9.81 joules. You lower same mass 1 meter and you get back 9.81 joules. What’s the controversy? Are you going to tell me that there are different laws for going up and down?

19

Konrad: <<Are you going to tell me that there are different laws for going up and down? >>

Different laws? No. Different effects of gravity? Yes.

I have a ball at rest on a stair in the middle of a stairway. I give it a horizontal push of two inches towards the edge of the stair. The ball bounces down the stairs, pulled by gravity.

Are you telling me that it can fall up?

Or that that same amount of force (the horizontal push) could propel the ball to the top of the stairs?

If you’re being serious, Konrad, then you’re talking about the total energy of the whole system (or in a gravity-free vaccuum). The rest of us are talking about the additional force needed needed to propel up vs down.

20

You’re not talking about the right energy here. The energy you put into a ball to get it to go down the stairs doesn’t even come into consideration because it can be infinately small as long as the ball is right on the edge. The energy that we’re talking about is the energy the ball gains as it falls down the stairs. The ball speeds up as it falls down, right? And the longer the flight of stairs the faster the ball is going at the end. But humans are not like a ball, they do not speed up as they go down stairs because they slow themselves down by absorbing the energy of each step down.

Now the proof that the energy is the same:

You should know that if a ball that fell down the stairs then (neglecting friction) went on a ramp that launched it straight up it would reach the same height that is was released at. Therefore the kinetic (speed) energy that the ball gained from going down the stairs is exactly equal to the potential energy lost.

A person will absorb the speed they gain after going down each step so that they don’t speed up after each step and break their necks. The energy they must absorbed is equal to the energy it takes to slow them down after each step. This is equal to the potential energy they lost at each step. And the potential energy is by defintion the energy it takes to go up the steps.

I realize this is not a very clear explanation but the main point is that (if you want to use the ball analogy) it takes more energy for a ball to go down the stairs then just the initial push. You have to slow it down at the end of those steps so that it is going as fast as it was when it started falling. That way it simulates the way a human goes down.