Junk Miles - Is it the runner's proverbial unicorn?
Junk miles, you may have heard all about it, but what exactly is it? Is this a foundational truth or some mythological creature made up? Usually it is associated with the runner who has some number of miles they need to run in the week. And then that runner tries to plan out the week for each of their runs. A certain day they may have a tempo planned. Another day they have hill repeats planned out. Then they have a long run planned at the end of the week. This only makes up a small portion of the miles they need to get in during the week. So the rest of the days are filled in with a bunch of easy runs. The idea is that if you are only running those extra miles just so that you make it to some magical number you had in your head, then those extra miles are junk. They don't contribute to some physiological development. You are just running them to say you ran them with no real purpose. Well that is the idea behind “junk miles”.
I'm a big fan of building big mileage. The key thing is to build up your mileage slowly. And building more mileage is a great training stress on your body. So while you are building mileage (especially if you never ran that many before), I would encourage you to run them at an easy pace. You are making big changes to your heart and your aerobic metabolism.
You are also making big changes in your running muscles, your bones, joints, and all of the connective tissue. They will become stronger as you gradually add more miles. Now how long do you keep adding more miles? How much is enough? When is it too much?
Well, the rate you increase miles each week depends on how fast your body adapts to the increased miles. Add too many miles too fast, and your body will be over trained which will lead to injury. So you have to increase miles in a way that allows your body to incur just enough training stress, and provide the time for recovery so that your body can adapt and make the changes I mention above so that you become a stronger runner.
So how long do I keep this process up? Well there are so many facets to running that all need to be put together to make a good decision. Lots of slow miles will lead you to become a stronger runner both aerobically and physically. But eventually you will need to address something very important. Running all of your miles at some mediocre medium. The point you become very stagnant in your running.
It helps first to understand periodization. That is, to break down a single year worth of training down into smaller phases known as macrocycles, and then you break those macrocycles down into smaller mesocycles. All of those metacycles and mesocycles lead up to some key goal race. As you reach a new metacycle or mesocycle, your training will need to be modified. Your focus changes each time you progress into a new metacycle and mesocycle.
See the following references:
http://www.runnersworld.com/race-training/the-three-phases-of-a-running-programcom
http://www.runningplanet.com/periodization-for-distance-runners.html
http://www.active.com/running/articles/how-to-use-periodization-to-achieve-your-running-goals
So in the early metacycle(s) base building and mileage building become important. But as you move into a new phase, you may decide to maintain mileage and focus on other things. You may exchange some of those easy miles you were doing during mileage building and replace them with some fartlek runs, or some tempo runs. Sprinkle in some anaerobic workouts. But increasing mileage stops while you work on other things. Eventually you will start back over after your key race and the base building phase begins again. During that time, you will go back to all easy runs while you increase your weekly mileage again.
Next comes the fad, run less run faster.
This is when people begin to rethink large mileage and become more focused on key workouts. Usually 3 quality workouts which usually includes the long run. You do anything else (so they say) and those extra miles become “junk miles” which takes away from the quality workouts. It's the key workouts that will make specific physiological gains. The extra miles (as the theory goes) really don't contribute to a physiological change and just makes you more tired so you can't perform as good on quality day. In other words, you need to recover from your key workouts, so that when you return to your key workout, you are stronger. The same people will tell you that the additional aerobic training can come from other cross-training workouts. So if you are not running, you are swimming, or riding a bike, so that you can give your running muscles a break. This is what we call "active recovery". It's this concept that I now like to concentrate on.
But for now, there are those on the side of larger training volume to get better:
http://running.competitor.com/2013/10/training/are-you-running-enough-miles_35813
http://running.competitor.com/2012/12/news/mo-farah-increasing-training-mileage_63458
http://www.telegraph.co.uk/sport/othersports/athletics/8627789/London-2012-Olympics-Mo-Farah-told-he-will-be-even-stronger-and-faster-by-next-years-Games.html
And then there are those that think running less volume more key workouts are better:
http://strategicathlete.com/better-run-faster-fewer-miles/
http://www.runnersworld.com/race-training/marathoning-the-hansons-way
And then there's the method I actually endorse and attempt to follow personally, which is keep the philosophy of your key workouts in the appropriate training phases, but maintain the mileage you built from previous phases.
Instead of cross-training for your active recovery, you do "recovery runs".
To understand this, you really have to know how to run a recovery run. This will make the difference between what people call junk miles to what I call recovery runs. So why is the recovery run better in my opinion than cross training or complete rest?
First off, I will advocate to use cross-training to supplement your training as a way to strengthen those supporting muscles that may be already weak. The idea is that you are strengthening them to prevent injury that is normally associated with the higher volume running. It's not a way to replace those miles. So performing core and leg resistance training would all be good. Maybe swimming would be good if you are nursing a leg injury. But I wouldn’t personally endorse them to actually replace a training run.
When I set a goal, I have in my mind that I will need to run a certain number of miles during the extent of my full training in order to prepare myself to complete that goal. The only way to improve those specific running muscles is to actually run more. Swimming will lead to improvements in my swimming muscles. My swimming muscles and the muscle memory developed during swimming won't help me much in running. Now, will swimming make my heart a little stronger? Yes it could, but so could easier paced running and I get the added benefit of targeting the specific muscles that are used in running.
But you may ask, don't I have to give my running muscles a break to give them a chance to recover? Otherwise, won't I over train them which will lead to injury? Not if you already slowly built your base, and you understand how recovery runs work.
Realize first, if you never ran a lot before, you are not going to run 5, 6, or 7 days a week. You build up to that over time. The idea is not to get heavy volume in overnight, as Rome was not built in a single day. In the beginning, those days off from running will be more beneficial to you. But as you progress and you need to increase your training in order to continue incurring a training stimulus, then you need to attack it from different ways. You can continue to increase your training stimulus by either increasing the volume, increasing the intensity of the effort, or decreasing the rest period. I advocate a strategy that makes use of all 3 methods.
Before you can understand what recovery runs are, you need to understand what "active recovery" means.
So during your workout, you incur a training stress. That training stress causes a minor breakdown or damage to your body. This damage stimulates your body to rebuild that part of your body during the recovery period in a way that the body part actually becomes stronger than before. We call this "adaption to training". That way, we can go back and repeat the training stress to incur more damage which will stimulate more adaption. During recovery, you give your body a chance to repair itself as you provide it rest and proper nutrition. There comes a time when you repeat the same training stress, but your body has adapted so much that further adaption no longer occurs after recovery. The recovery is not as effective because there isn't as strong of a stimulus for adaption. So you need to increase the training stress.
But are there things you can do during recovery that will aid in the adaption process? Other than just doing nothing. That is where active recovery comes in.
Realize that the damage we are talking about during training stress is minor. Major damage would be as a result of overtraining. But for a training stress, the damage is just minor enough that we will be able to repeat the training stress only after a short recovery. The minor damage may be felt as Delayed Onset Muscle Syndrome (DOMS).
After your big tempo run, your running muscles will incur small microscopic tears in the muscle. Your body will gather more water around the area to protect the damage muscles during recovery. This will lead to swelling and inflammation. But the swelling can also lead to slower blood reaching the damaged area. Because blood is restricted to the area, fluids, oxygen, and key nutrients cannot reach the cell in a timely manner. Blood leaving the damage area with waste products may also be restricted especially as they have to defeat gravity to make it back to the heart. Compression may help in this area.
But what if you could increase the intensity of your blood pressure oh just slightly so that more nutrients can travel through the blood to the damaged area and force waste products through the blood out of the damaged area? That is the concept behind active recovery. But there are also some other interesting science in how the body works.
Training stress not only causes minor muscle damage. It also depletes glycogen in your muscle (the stored carbohydrate used for energy). Your muscles need more sugar to manufacture more glycogen to replace what was lost. Be careful however that too much sugar will promote fat production. Sugar (as well as proteins and fats) reaches our muscle and will enter the muscle through different metabolic pathways. The pathway used will depend on the body's needs at the time as well as the amount of macronutrient being offered.
In order for a muscle cell to accept a single sugar molecule, a transporter inside the muscle cell has to be activated to receive that sugar and guide it into the muscle. The body will release certain enzymes in the body to guide the sugar molecule over one particular pathway as opposed to a different pathway. Insulin acts as a receptor to the sugar to guide it through the blood to the muscle so the transporter can receive the sugar as it crosses over the cell membrane. Insulin acts like the key to open the cell membrane door and the transporter acts like the key hole. When the brain senses that a high amount of sugar is present in the body (usually after eating a high carbohydrate meal), the brain will signal the pancreas to release more insulin into the blood stream. Higher levels of insulin will trigger the cells to receive more sugar so that sugar levels in the blood is reduced. Combined with other enzymes that will be released, the pathway could lead the sugar into the muscle cell for either energy or glycogen production, or it would go down the pathway into an adipose cell where fat will be manufactured. When sugar is forced into a cell as a result of increased levels of hormones, we call this uptake. We want to increase sugar uptake as well as protein uptake into the muscle cell during recovery.
The particular transportation mechanism which uses insulin as a trigger for glucose reception is known as the Insulin Stimulated Pathway. GLUT4 is a vesicular tube that guides the glucose sugar inside the muscle cell after it crosses the cell membrane. The GLUT4 vesicular tube will become activated once the insulin receptor is triggered and glucose comes in contact with the cell membrane. Once the glucose sugar is transported across the cell membrane into the skeletal muscle, the GLUT-4 can transport the glucose molecule into the Glycolysis Pathway (in order to convert it into ATP for immediate energy) or it can transport the glucose molecule into Glycogenesis (medium term storage that converts glucose into glycogen) or into Lipogenesis (long term storage that converts glucose into fat).
But there is a different type of transportation mechanism that allows sugar to enter into a cell. This other transportation mechanism that does not involve insulin, but rather exercise is known as Contraction Mediated Pathway. During exercise, a different GLUT4 vesicular tube can be activated without the need for the insulin receptor to be triggered. This allows sugar uptake to be increased into the muscle cell without the need to have increased levels of insulin. During intense exercise, an enzyme called adenylate kinase (ADK) inside the skeletal muscle cell will be released. The ADK will have a key role in a very complex process to trigger an AMP activated protein kinase called AMPK in order to recruit the other GLUT4 vesicular tube to the surface of the muscle cell to allow glucose in. Therefore, exercise can increase glucose uptake into skeleton muscles. And long term exercise training stimulates insulin sensitivity.
Understanding the 2 transport mechanisms that I just described and how you can use both in conjunction to stimulate an increased level of recovery is key to active recovery. The AMPK activated transport mechanism will in essence turn on the flood gate to allow lots of glucose into the muscle cell for immediate energy production during exercise. The downside to this process is that protein synthesis (the process we actually want to occur during recovery to allow adaption to happen) is stinted. Protein synthesis is energized by the Insulin Stimulated Pathway. The key thing to note is that insulin will shut down AMPK so that it no longer will stint protein synthesis. So the concept is to use a brief low intense session of running to allow the Contraction Mediated Pathway to open the flood gate for glucose to enter those particular muscle cells followed immediately by a small meal of quick absorbing carbohydrates that will trigger increased amounts of insulin into the bloodstream to shut down AMPK so that sugar can be used as part of protein synthesis process. In order for protein synthesis to occur, you will also need to consume quick absorbed amino acids (broken down protein) with that small meal of carbohydrates immediately following your recovery run. Basically what I just said is that exercise will allow for a small window of opportunity where a small meal of quick digesting carbohydrates and protein followed immediately after the workout will greatly increase the uptake of protein and sugar to rebuild muscle tissues. This small window of opportunity is the greatest within 30 minutes after the workout is completed and will continue up to 60 minutes after the workout.
Another benefit to a recovery run is training your muscles to become more efficient at running when tired. When we run (or perform any type of muscle contraction) the brain has to decide which muscle fibers within the muscle group to use to perform that particular exercise. There are 3 types of muscle fibers that could be used: the Type 1 slow twitch fibers, Type 2a fast oxidative fibers (also known as medium twitch fibers), and Type 2b fast glycolytic fibers (also known plainly as fast twitch muscle fibers). If you decide to just burn rubber and go into a sprint, it’s the Type 2b fast twitch muscle fibers that will be recruited. If you are going to set out for a long slow job, then your Type 1 slow twitch muscle fibers will get recruited. Muscle fibers can wear down and become tired as exercise continues. Your type 1 slow twitch muscle fibers have the longest endurance while the Type 2b fast twitch muscle fibers have the shortest endurance. During a very long run, muscle recruitment will undergo a recruitment ladder. If you start your run in a slow jog, your Type 1 muscle fibers will first be recruited. As you continue your run, over time, those fibers will get tired and your brain will now ask your Type 2a medium twitch fibers to take the place of the slow twitched ones. Eventually those fibers will get tired and your brain will now ask the Type 2b fast twitch muscle fibers to continue the effort. In a recovery run, you begin your slow jog in a state where your muscles are assumed to already be tired. This will quicken the process to progress through the recruitment ladder without having to run very far or very fast. This gives your entire system more time to practice recruitment of all 3 muscle types thereby simulating running very long distances without actually running those long distances.
The next benefit to active recovery is training your neuromuscular development. This is another benefit related to becoming more efficient at running while tired. When you run, your brain will send neurological signals from your brain, through the nervous system, and to the muscles fiber cells to command them to contract. At the same time, your body is sending diagnostic signals back to the brain through the same neurological system but in reverse. These diagnostic signals could signal the brain that blood sugar is running low, or that core body temperature is running too high, or that certain muscle fibers are getting too tired. As the body weakens from a long exhausted run or race, these signals can become compromised or the brain may not interpret them correctly. The brain and body can be trained to become better at signaling under very strenuous situations. The recovery run is one great way to help train the body and brain at becoming more efficient under very strenuous situations without having to run the actual distance you may run in a very long race. The key thing to observe during a recovery run is to always practice good form during your recovery run. If your body is too tired that your form is actually compromised, then it is no longer beneficial to perform a recovery run, and instead consider a full rest.
Recovery runs can also be therapeutic in that it gives you a time out mentally. You can relax, and enjoy the run without worrying about a workout pace. Running in of itself can be a great stress relief where the body will release those feel good hormones. This can even happen on an easy effort recovery run. Again keep good form, but just go out and enjoy yourself. Let your body dictate the pace and don’t worry about it being a big mileage day.
So in conclusion. Recovery runs are very beneficial for advanced runners. They help increase the heart rate to deliver blood and nutrients to sore inflamed muscle tissue where swelling may slow the delivery of blood to the tissue. They help reduced the tightness and soreness you may be normally feel during recovery as waste leaves the muscle due to the increased heart rate. The recovery run has been shown through research that glucose and protein uptake will temporarily be increased for 30-60 minutes immediately after the run to aid in recovery. And the recovery run will allow your body to train for longer distances by becoming a more efficient runner while tired.
The key things to remember during your recovery run are:
- Keep the distance relatively short and intensity relatively light.
- Let your body dictate the pace
- Always continue to practice good running form
- If you cannot maintain good form, rest completely instead
- Have a small meal of quick digesting carbohydrates, proteins, and water within 30 minutes after completing your recovery run
- Recovery runs are more useful to more advanced runners
- Beginner runners will benefit greatly from complete rest
- When adaption is no longer perceived with complete rest, consider active recovery instead
- Recovery runs give you more practice at running while tired without having to cover the entire race distance in a training run
- Recovery runs can help you feel more refreshed in between key workouts
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