Exercise... Bad For The Immune System?!

Ever wonder why you felt cold-like symptoms the morning after a hard workout?  While exercise has always been known to provide a long list of health benefits, it may be surprising to hear that exercise can actually hurt the immune system.  Depending on the intensity, duration and the time spent on recovery, the immune response to exercise can be either good or bad.  Researchers who investigated the relationship between the immune system and exercise found that two changes typically occur.  Both cell production and their function changes after a bout of exercise (1,2,3,4,6).  Negative changes in the immune system tends to occur with continuous endurance exercises and interval training.  This news probably sounds ridiculous since that describes just about every type of aerobic workout, but don't worry, I'll explain how to prevent this problem from occurring.

IMMUNE SYSTEM 101:
If I were to say that neutrophil production increased as a result of exercise, this wouldn't mean much to anyone without knowing what a neutrophil is and what it can do.  To get around this, I compiled a list of immune cells which may be directly affected by exercise and describe each of their functions (5).

• Leukocytes:  A fancy word for white blood cells.  The two major types of leukocytes are lymphocytes and phagocytes.
• Neutrophil:  These cells are the kamikaze fighters of the body.  Naturally, there is a greater number of neutrophils than any other immune cell in the body.  This is a good thing because when a neutrophil engulfs an antigen to kill it, the neutrophil also dies.  Neutrophils can also kill bacteria through oxidative bursts which are highly oxidized chemicals toxic to bacteria.
• Monocytes:  If a T cell happens to miss an antigen, a monocyte will find it and bring it back to the T cell.  Monocytes cannot destroy antigens- they can only find and deliver the antigens to the cells that can kill them.  Monocytes which leave the bloodstream turn into macrophages, a form which has the ability to destroy antigens through oxidative bursts or phagocytic activity.
• Natural Killer:  Rather than targeting an antigen, NK cells engulf cells which look unnatural on the surface such as tumor cells.
• B & T Cell:  The B lymphocyte and T lymphocyte cell is designed to identify specific antigens and once identified, they will multiply and destroy infected cells, respectively.

THE GOOD & BAD- HIGH INTENSITY AEROBIC EXERCISE:
In high intensity continuous aerobic exercise lasting less than 45 minutes, neutrophil production and function is at its greatest.  This increase has been shown to remain higher than normal two to four hours after exercise (5).  During this time, the neutrophil also becomes more active, destroying antigens and removing waste that was caused by the exercise bout (4,6).

In contrast to improved neutrophil production and activity, monocytes do not see the same benefits.  Although the number of monocytes produced is higher after high intensity exercise, they become less functional as a macrophage, the form which is able to directly destroy antigens.  The specific function which appeared to become suppressed was its ability to use oxidative bursts to destroy waste products (3,4,6).  After a high intensity exercise bout, monocyte levels remain higher than normal for about two hours (5).

The same problem occurs with NK, T and B cells.  Although cell production increases after high intensity continuous aerobic exercise, the activity of all these cells drops below resting levels about two hours after the exercise bout.  NK cells lose function for two to four hours.  T and B cells lose function for one to two hours (5).  Losing function in these cells for such a great time leaves the body more susceptible to infection and sickness (1,4).

Longer duration high intensity exercise tends to exaggerate the effects found with shorter duration exercises lasting less than 45 minutes (5).  The only exception involves reduced function of the neutrophil (3,4,6).

HOW CAN THIS INFORMATION BE APPLIED TO AN EXERCISE PROGRAM?
Notice that the type of exercise associated with decreased immune function involved high intensity aerobic exercise which got worse as duration also increased.  In contrast to high intensity aerobic exercise, moderate intensity aerobic exercise was shown not to cause the cells of the immune system to lose function or slow cell production.  In fact, moderate intensity exercise either caused an improvement or no change to the resting levels of immune cell activity.

The key point to take away is to try to avoid doing too much high intensity exercise.  There has to be enough time dedicated towards moderate intensity workouts to allow the body to make the necessary repairs so that it can continue to meet the demands of training.  This idea might sound familiar because it's one of the key principles of exercise program design- recovery!

So next time the urge comes on to go all-out all the time, remember that it will come back to bite in the form of an injury related to residual waste which never had a chance to exit the body.  Try to remember that patiently moving through an exercise program will get the results better than rushing workouts through "quick fix" routines that focuses mainly on high intensity and less on moderate intensity.


References:

1. Nieman, D.C., L.M. Johanssen, J.W. Lee & K. Arabatzis: Infectious episodes in runners before and after the Los Ange-les Marathon. Journal of Sports Medicine and Physical Fitness. 30:316–328 (1990)
2. Nieman, D.C., K.S. Buckley, D.A. Henson, et al.: Immune function in marathon runners versus sedentary controls. Med-icine and Science in Sport and Exercise. 27:5986–5992 (1995b)
3. Nieman, D.C.: Immune response to heavy exertion. Journal of Applied Physiology.82(5):1385–1394(1997a).
4. Woods, J.A., J.M. Davis, J.A. Smith, D.C. Nieman: Exercise and cellular innate immune function. Medicine and Science in Sport and Exercise.31(1):57–66(1999).
5. Plowman, Sharon A., and Denise L. Smith. Exercise physiology for health, fitness, and performance. 3rd ed. Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins, 2011. Print.
6. Woods, J.A., J.M. Davis: Exercise, monocyte/macrophage function, and cancer. Medicine and Science in Sports and Exer-cise. 26(2):147–157(1994).

Planet Bike Protege 9.0 Bike Computer Review

I was very happy with the $40 I spent on the Planet Bike Protege 9.0 bike computer from REI.com.  This was the first bike computer I have ever used and since day one, this computer has been very reliable even in extreme conditions from below zero wintry conditions to 100+ degree summer temperatures.  Just like any other computer, as long as the computer is installed correctly, this computer can be a five star product.  Mine has consistently measured all of the basic information that it was designed to monitor such as speed, average speed, maximum speed, ride time, distance, time of day, total distance (odometer) and temperature.

WIRED VS. WIRELESS
A computer can have a lot of nice features on paper, but if it doesn't perform well in actual riding conditions, that's money wasted.  Since I was only willing to spend around $40, I chose to get a wired computer to avoid the likely problem of a poor quality wireless connection which I have heard was a big problem with budget wireless computers.  Rain, snow or mud (happened on accident), this computer has never failed to work, so I'm happy!

If you don't want to include the data from the warm up or
cool down, you'll find out that there's no pause button.  Just
unclip the computer off the electrode to cut off the
connection.  Now it has a pause function!

THE GOOD:
With over two years of use about 4-5 days per week, the Planet Bike Protoge 9.0 has excellent "battery economy."  The Protoge 9.0 does a good job at saving energy by using their trademarked "MacroMonitor" display similar to the display on a calculator.  In terms of visibility, the display was especially visible in overcast and sunny conditions- see the picture to the right.

The feature I liked the most was the convenient design they integrated to make navigating the menus so easy that you would never need to take a hand off the handlebar (unless you're on the drops).  With both hands on the hoods, all I had to do was take a thumb out and press the computer forward (towards the tires) to switch screens.

Another feature that I tend to take advantage of a lot was the average speed indicator.  Whenever my current speed would fall above or below the average speed, an arrow will point up or down, respectively.  This helps when the display is set to a screen that doesn't show average speed.

THE BAD:
The lack of a back light makes the display almost impossible to read.  I say "almost" because with a small helmet or visor light, the lack of a back light really isn't a problem at all.  Aside from the extra cost of buying a visor light, there really isn't that much more to improve that wouldn't up the cost of this computer.

I have to admit that it does sort of suck not having visual feedback for cadence.  To get around not having cadence, I've been using a metronome app from my phone to estimate cadence, although it would help a lot more to have real-time feedback.

THE THERMOSTAT TEST:

All cycling computers must pass this test!  It would be a real disappointed if a cycling computer managed to fail a simple feature like this.  Since the Planet Bike Protoge 9.0 had a temperature feature, I tested it out.  As shown in the picture to the left, Planet Bike passed!  Click on the image to enlarge it- I had really bad lighting when I took the picture.

Sensor attached to rear side
of the fork.

INSTALLATION TIPS FOR THE CARBON FORK PEOPLE:

Keep the magnet as close as possible
to the sensor for better readouts

With a carbon fork, installing the Planet Bike Protoge 9.0 is still possible to do.  Rather than using a less flexible zip tie to hold the sensor against the fork, use electrical tape and tightly wrap the sensor.  Electrical tape was designed to withstand heat, water and cold, so there's nothing to worry with regards to durability.  Be sure to place the sensor near the back of the fork- this is extremely important.  Placing the sensor in the back will prevent the magnet from smashing into the sensor if you happen to make a mistake with installation.  Notice how close the magnet must be to the sensor.  This is pretty much standard protocol with any cycling computer.

Body Fat... Why Measure It?

There are two good reasons to measure body composition.  It provides an objective way to track progress towards better health or fitness, and it directly affects performance.

Fat cells aka adipocytes (above) store lipids in two ways.  White fat cells store lipids in one giant mass, and brown fat cells store lipids in groups of many little sizes. Humans carry more WFC's than  BFC's (5).

ASSESS TO PREVENT OBESITY:
There are short term and long term changes that a fat cell can undergo.  Think of the fat cell as a balloon that duplicates itself after reaching its maximum size.  When fat intake rises, the first physiological change that occurs is an increase in size (up to 10x larger) caused by the storage of lipids (3).  This is a short term change which can be restored through dietary and exercise interventions.  If nothing is done to reduce the amount of lipids stored in each fat cell, eventually the fat cell will undergo cell division as well as the maturation of precursor cells to fat cells (2,3).  Basically, you'll end up with more fat cells than you started with.  Generally, someone with a normal percentage of body fat has about 30 to 50 billion fat cells whereas an obese individual can have 75-80 billion fat cells (3).

After the original fat cell undergoes hypertrophy (enlargement), it remains the same size even when emptied.

If the new fat cells have time to mature, they will also (permanently) remain the same size despite a significant loss of body fat (4).  In other words, the balloons will deflate, but they'll remain on standby;  eagerly waiting to store more fat.  This is a major reason why obese people who successfully loses weight cannot maintain the weight loss.  This is why body composition tracking is extremely important.

BODY COMPOSITION TESTING BENEFITS EVERYONE:
Just as important as it is to prevent excess body fat, it's also important to prevent body fat from getting too low.  Young women and athletes who benefit from a low body weight are particularly at risk for eating disorders (1).  Pay attention to the fine line between attention and obsession with regards to body weight or composition.

Changing body composition affects the metabolic systems.  If less fat is available to use as energy, more carbohydrates will be fed into the LA system.  The goal for endurance sports is to primarily use fat, and save carbs for the harder parts of a race.

Because the relative proportion of bone, muscle and fat are directly affected by changing body composition, performance may decrease due to a shift from homeostasis or equilibrium.  Remember that both anaerobic and aerobic metabolic systems are used simultaneously, but at different percentages.  Because the mitochondria are located in fat and muscle, reducing fat mass will leave the mitochondria with less accessible fat to use as energy.  With a healthy diet, the body will naturally take on the optimal body fat percentage.

WHO BENEFITS THE MOST FROM REGULAR BONE DENSITY TESTING?  The older population benefits the most, especially those who are at a higher risk of falling.  Early detection helps determine if the current regimen of exercise, nutrition, and supplementation is adequate.  Surprisingly, road cyclists, including professional cyclists, also have a high risk of developing sarcopenia or below normal bone density.  See my post that covers this topic separately, Low Bone Mass in ROAD Cyclists and Ways to Fix it. 

THE SEVEN WAYS TO MEASURE BODY FAT:

There are six popular ways to measure body fat.  I ranked the assessments based on most accurate (#1) to least accurate (#6).

• Body Fat Assessment #1: Hydrostatic weighing
• Body Fat Assessment #2: Skinfold Meaurements
• Body Fat Assessment #3: Bioelectrical Impedance
• Body Fat Assessment #4: Body Circumference
• Body Fat Assessment #5: Waist to Hip / Waist Circumference
• Body Fat Assessment #6: Body Mass Index "BMI

REFERENCES:

1. Kaminsky, Leonard A..ACSM's health-related physical fitness assessment manual. 3rd ed. Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins Health, 2010. Print.
2. Malina, R. M., C. Bouchard, O. Bar-Or (2nd ed.): Growth,  Maturation and Physical Activity. Champaign, IL: Human Kinetics (2004).
3. Plowman, Sharon A., and Denise L. Smith. Exercise physiology for health, fitness, and performance. 3rd ed. Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins, 2011. Print.
4. Sjöström, L., & P. Björntorp: Body composition and adipose tissue cellularity in human obesity. Acta Medica Scandinavica. 195:201–211 (1974)
5. Malina, R. M., C. Bouchard & O. Bar-Or: Growth, Mat-uration and Physical Activity (2nd ed.) Champaign, IL: Human Kinetics, 163 (2004). Reprinted by permission.

Body Fat Assessment #3: Bioelectrical Impedence

WHAT IS IT?
Bioelectrical Impedance or BIA is an indirect method of determining body fat percentage by measuring the amount of resistance the body provides when a current of electricity is passed through the body.  A high or low resistance corresponds to a high or low body fat percentagE, respectively.

HOW IS IT DIFFERENT?
Compared to other methods, this is the least invasive and most comfortable way to assess body fat.  Unlike other methods where they are only effective if the individual wears short running shorts with no shirt, the only body parts that need to be exposed with BIA are the hands and the feet.  The BIA machine I used involved only two pairs of electrodes which needed to be placed on my right hand and foot; afterwards, all I needed to do was lie down supine (on my back) and relax while the machine did all of the work.  Very easy and less painful than the deep folds that need to be pinched for skinfold measurements.  While I'm on the subject of pain, it's also worth mentioning that BIA doesn't hurt and is in fact, the electrical current is so weak that it is unnoticeable- only the machine itself can detect the current.  The only thing I found painful was removing the electrodes and some of my hair at the same time.  This is still less painful than the pinching and pulling required for skinfold measurements.

LIMITATIONS & SOLUTIONS:
In terms of comfort, invasiveness, convenience and ease of execution, BIA is a great assessment to use.  Its only flaw involves a few conditions where its accuracy may become questionable.

• Limitation #1 - Hydration Affects BIA:  Because electrical currents may become affected by water and electrolyte levels, the individual's hydration and nutritional status must be kept within normal limits to get more accurate results.  Too much water would theoretically decrease resistance and the body fat percentage; although studies have also found the opposite to occur in two conditions: During exercise and after consuming a large quantity of sport drinks (3).  I'm not sure why anyone would do either during a BIA test though...
• SOLUTION:  To get around this problem, it is recommended that the BIA be done three to four hours after a meal or an exercise session (3).
• Limitation #2 - Ambient and Skin Temperatures Affects Resistance: When the temperature of the testing area is cool, resistance will be higher- the opposite is true for hot temperatures (2,4).  This same relationship also holds true for hot and cold skin temperatures (2,4).
• SOLUTION:  If you're going to take a BIA measurement, make sure the room has a neutral temperature of 27-29 degrees Celcius or 80-84 degrees Fahrenheit (3).  Also make sure that you are neither overheated or chilly.  Get to the assessment on time so that you won't have to literally run or speed walk to make it in on time- even a quick sprint will cause skin temperatures to rise quickly.  If it is cold outside, dress appropriately so that your skin temperatures adjust more quickly to the temperature of the room.
• Limitation #3 - BIA Equations Vary By Make/ Model of Machine: Don't get angry if the measurement taken at your first assessment does not agree with the measurements you received at new place.  Because there isn't a universal equation available for BIA, the manufacturer must "tailor-fit" their equation to match their machine.
• SOLUTION:  There really isn't a way to get around this but to try to find a new place that uses the same BIA equipment.
• Limitation #4 - Inaccurate on Individuals with Normal %BF:  Due to a combination of the above limitations, BIA cannot accurately measure individuals who are not at the extreme of leanness or obesity.
• SOLUTION:  According to a study, although BIA is accurate under standard conditions, BIA is probably no better than skinfolds (1).  So if accuracy is top priority, it might be wise to stick with skinfolds from the start to avoid headaches in the future.  This is the final limit of BIA where it is basically useless as a way to track progression.  The best method at this point is to use skinfold measurements to track where fat is being stored at specific sites in the body.

REFERENCES:

1. Baumgartner, R.N., W.C. Chaunlea, & A.F. Roche: Bioelectrical impedance for body composition. In K.B. Pandolf (ed.), Exercise and Sport Sciences Reviews. Baltimore, MD: Williams & Wilkins, 18: 193-224 (1990).
2. Caton, J.R., P.A. Mole, W.C. Adams, & D.S. Heustis: Body composition analysis by bioelectrical impedance: Effect of skin temperature. Medicine and Science in Sports and Exercise. 20(5):489-491 (1988).
3. Plowman, Sharon A., and Denise L. Smith. Exercise physiology for health, fitness, and performance. 3rd ed. Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins, 2011. Print.
4. Stump, C.S., L.B. Hourkooper, M.H. Hewein, S.B. Going, & T.G. Lohman: Bioelectrical impedance varability with dehydration and exercise. Medicine and Science in Sports and Exercise. 20(2):S82 (1988).