I didn't see anything in those articles about utilization of protein during aerobic exercise. The primary sources of energy are carbohydrates and fat.

Yes, you are right. While Carmichael says, that article doesn't back that up with data.

But this one does:
https://www.hammernutrition.com/knowl...wledge-sectionIt is true that many cyclists lose muscle mass during long, intense rides. The above link explains the mechanism. You are also right that carbohydrates and fat are the primary energy sources, however that does not mean that protein is not burned. We all go calorie-negative during anything above an easy ride. During those rides, protein is burned. That said, my experience is that it is not necessary to lose muscle mass if one doesn't want to.

The other thing that's going on is that many cyclists have discovered that the lighter they are, the faster they climb, and not just lighter because of low body fat, but lighter in terms of less muscle mass. As some of us here are fond of pointing out, cycling does not require a lot of muscle mass. Lance had to lose 7 kilos of protein to be competitive during his come-back TdF.

I'm always a little sceptical of references to Hammer nutrition as they have an interest in selling products. In any case, the amount of protein oxidized during exercise is generally an estimate as it is more difficult to measure compared to carb and fat oxidation. I have looked but haven't found any research showing a performance benefit to ingesting protein while exercising. Here is an interesting quote from Branched-chain amino acids as fuels and anabolic signals in human muscle.

Did you look at any of the references Hammer provided? I don't think they have any skin in the game of predicting protein utilization during exercise. They could mix up product with all sorts of characteristics and still sell it with a good marketing campaign. Doesn't have to contain much, if any protein, witness the many products on the market which contain little or no protein.

We could trade quotes back and forth all day. You cherry-picked that quote about leucine, but the abstract seems to disagree with that quote, the first sentence reading:
I have a riding buddy who holds three records in a local LD (297 mile) endurance race. He reports that his power falls off unless his on-bike food contains more than 15% protein. The Hammer fuels contain protein. Endurox contains protein. Ensure contains protein. Spiz contains protein. These or compositionally similar fuels are chosen by nearly all LD racers. I don't think it's their imagination. Most trainers recommend about 20% of calories be protein for LD riders.

I'm a vegetarian. I normally supplement with whey protein, because I've found that if I don't, my legs become very painful on the bike and my power falls off. On our recent tandem tour in the Czech Republic we took no supplements and drank only water in our bottles. By the 4th day I felt I was losing power, and started eating chicken once/day. That really helped.

I don't think protein is unnecessary for endurance athletes. I also do not think that cycling protein requirements result from the same source as for bodybuilders: muscle damage or microtears which need to be repaired. Cycling does not impose the sort of muscle overloads which bodybuilders seek. Rather protein is necessary to replace amino acid oxidation during exercise.

https://www.bodyrecomposition.com/mus...ass-gains.html

Conclusion is that aerobic activities don't make you loose muscle. What does make you loose muscle is having a calorie deficit, especially if you don't eat enough protein.

How many people are doing 300 mile races?? Not very many. My comments about not needing protein are during the normal training that 99.9% of people do and don't involve many rides over 5 hrs. Once you're into very long races like your friend you obviously have to eat some protein while exercising as you're either on the bike or sleeping. That isn't Hammer's target market.

I did look at some of the references from the Hammer paper but they were so old (i.e. 1989) they weren't available on-line.

I wasn't disagreeing that you need to get roughly 15% of your daily calories from protein. I just haven't seen anything that requires it while riding (other than super long races I never do!).

For the gentle reader, the important takeaways from this discussion are that cycling need not "kill muscle", unless perhaps one is greatly over-muscled, that no study has ever shown decreased performance from using a carbohydrate sports drink or a carbohydrate/protein sports drink, and that the major cause of muscle loss in cycling is inadequate nutrition (too few calories) while cycling.

The history of studies examining whether or not adding protein to carbohydrate sports drinks, in about a 4:1 ratio, began with a study by Ivy et. al. which found a huge benefit. Unfortunately this study was "flawed" because the subjects with the CHO+P drink got more calories than those with CHO only. However, some sports drinks, notably Accelerade, were developed using this study as a marketing tool. A later study, examining time trial performance, and using equal calories, found no benefit to adding protein while on the bike. More recently, a series of equal-calorie studies examining time-to-exhaustion have been performed which seem to validate the idea that adding protein to a carbohydrate sports drink increases time to exhaustion:

https://www.sportsperformancecentres....onsumption.pdf
https://www.nutritionexpress.com/arti...articleid=1547
https://www.ultramarathonman.com/news..._Endurance.pdf
https://www.drmirkin.com/fitness/2967.html
The above studies do not show that you'll go faster on a short ride or race if you consume protein, but they also don't show you'll go slower. They do show you'll go longer.

Does this work in the bedroom also?

Well, you bring up an interesting point . . .

Getting your protein on time is a big part of preserving muscle, it also smooths out blood sugar levels. But I think the most important point is that road cycling does not require much skeletal muscle. Even when out of the saddle, your legs are supporting far less weight than if you went for a leisurely walk. Without some kind of weight bearing exercise, any excess muscle (and bone) mass that is not required can be lost. There are also some hormonal issues at work with pure endurance work, but again mostly in the absence of regular weight bearing exercise.

Here's a bunch of basic info jumbled up quickly.

Certain muscles grow better with high/low repetitions. Cycling power is in the legs, so arms are basically wasted weight for cyclists. If one only cycles, their body will adapt as they are used very little, and legs will grow to support the cycling motions. Also, endurance sports lends itself to leaner athletes due to high energy requirements. Muscle growth basically has to do with low vs high repetitions, and nutrition.

Cycling "kills" muscle because a competitive cyclist (not your average person out for a recreational ride once or twice a week) is going anaerobic. Simply put, when you are producing the amount of energy we are discussing your body will pull from the easiest source of nutrition, fatty acids and glucose, once that is depleted it will start to pull nutrition form your muscles. Let's say you strength train 2 times per week for 30 minutes each time. You are building muscle which is the act of tearing down the tiny muscle fibers and then they heal and are bigger, now capable of a stronger load in strength. Well, if you go out a cycle for 1-2 hours 5 times per week and your body will eat your muscle once it has tapped out your fatty acids and glucose storages which it will quickly do with that much cardio. Again, we are not talking about the average person that is riding 10-15mph, but someone who is going all out for 1-2 hours at speeds of 16 at the slowest to 30 mph and watts of 150+ (lower watts for women).

You may be building muscle but it is nearly impossible to build it at the rate you would need to do of strength training to keep it on and the amount of protein you would have to consume based on the energy you are using to ride. Most riders also view it from a perspective of wanting to be lighter, the lighter you are the less weight you are carrying. While muscle helps you attain certain goals, too much bulky muscle will hinder you on endurance sports such as marathons, triathlons or endurance cyclists. You want to be lean and effective or what is called economy of exercise. A bulky body builder may be able to hit a sprint hard for 30 seconds to a minute but then he is finished and will struggle in hill climbs because he has so much extra weight in muscle and if you put a body builder on a bike long enough with the rides that are done weekly during training, he will start to lose his muscle within months as well.

So you cannot really say that you would have to intentionally starve yourself but in a sense your body is being "starved" during the anaerobic phases and so muscle is used as an energy source, it is rebuilt and then it is used again and the process continues until there is some type of a change.

Your understanding of the nutrition requirements for cyclists, competitive or not, is incorrect. Competitive riders don't exhaust their glycogen stores during a race even if the race is 6 hrs. There isn't a lot of anaerobic work during a normal road race.

Jesus. Your body shouldn't be breaking down muscle during your workouts unless your in crap shape and have terrible nutrition.

GB Cycling and Bradley Wiggins might disagree;-) He was apparently on a modified fasting diet (fruit only days once a week) in order to loose the 7kgs that it took for him to become a competitive climber instead of a track and tt specialist.

By the way, welcome to the board.

Endurance activity like cycling does consume proteins from the body, which is why cyclists' dietary protein requirements are high. If you get enough protein in your diet, you shouldn't lose muscle mass.

The recommended protein intake for endurance athletes is 1.2-1.4 g protein/kg body weight per day -- almost as much as strength athletes.

Thanks. I think both these posts agree with my statement - the nutrition component is key. A key point is that your protein requirements go UP as your bodyfat % and caloric deficit go down.

OTOH, if you want to get lighter, you can burn muscle cycling. Lance had to lose 7 kilos of protein for his come-back TdF. He did it by going out for 6 hour rides with only water in his bottles. Worked good.

Sorry, but, I don't agree at all with your contention that you need to be in crap shape or poorly nurished to be converting protein. A highly trained athlete on a high fatigue program can and will loose muscle mass, while being both incredibly fit and on a carefully balanced nutritional plan. It's the nature of endurance sport. If you're going to attempt to define "terrible nutrition" as any diet that doesn't provide sufficient calories to prevent such a situation, I'm going to counter that many of the sports greats have used just such an approach to win it's greatest accomplishments. Thereby suggesting that either it isn't 'terrible nutritinon' or that 'terrible nutrition' may be an integral part of achieving cycling success:-)


It is my understanding that protein requirements were most greatly determined by Lean Body Mass (muscle mass) and total stress or fatigue to that body mass. A low body fat % would impact ones reliance on carbohydrate in the diet as one would be more reliant on the carbohydrate in the absence of fat stores to metabolise.

As total caloric deficit does down, so does your total nutritional requirement. To state that you would require more protein is just wrong.


I think you might benefit from doing some reading on the subject before getting on too high a horse.

It's a combination / tradeoff between macronutrient ratios and total caloric content, yes. Of course, if you go cycle centuries with 10k ft gain everyday for a week, and don't provide enough calories or protein to even be somewhat close to your expenditure, you are going to burn muscle. And yes that's stupid and bad nutrition, unless it's your intent to do that. And you can sustain a larger deficit if a higher % is from protein (I'd suggest sacrificing fat)

I've read plenty of literature on the issue, thank you very much. I'd suggest you read more in depth.

Yes, as your bodyfat% goes down, your resting metabolic rate (RMR) goes down, as well as your nervous energy expenditure, so you tend to burn less, so the total calories needed goes down.

Unfortunately, you are missing the piece that as your bodyfat drops, leptin starts to crash, grhelin increases, and other wacky hormonal changes occur. In the end, it becomes harder and harder to burn fat.

So if you have a caloric deficit at low bodyfat levels, guess what happens? Your body will increasingly burn muscle since it doesn't want to burn fat. That's why higher protein requirements are needed at lower bodyfat levels. And there's plenty of research supporting that.

So, in summary, the best way to try to burn as much muscle as possible is to:

1) Have a low bodyfat
2) Burn tons of calories everday
3) Don't eat much food
4) Don't eat much protein

Luckily, if you don't do all those things (or at least with some sensible moderation), you'll be fine.

I've heard whole milk with whey added is the best for post lifting, and thats a lot cheaper than protein shakes. ymmv, but works for me.

Yes, but you also need to get enough total calories as well. Burning more than you take in and as fat stores get low enough the body starts to metabolize muscle and even organs, regardless of the composition of what you eat.

Holy Zombie Thread, Mr. Romero.

Well, there was a lot of wrong in this thread that needed to be resurrected and properly quashed. Maybe the muscle-eating fearmongering is dead now...

yea so true......i did myself while doing greenhouse farming and was not taking anything for lunch.i lost about 20 pounds in six weeks.