Exercises In Everyday Places: Shopper's Walk (Core)

We see these baskets in the front of the grocery store all the time, but the shopping carts always seem to win.  If the grocery list involves restocking milk, juice, eggs and fruit, grab a basket and work your way to a stronger core and better posture.

My current personal record for this exercise is two gallons of milk, two cartons of orange juice, one pack of 30 eggs, one bag of cereal, banana's and bagels.  With a little bit of Tetris skills, those baskets can hold a lot of groceries!

SHOPPER'S WALK HOW-TO:

Anyone familiar with the Farmer's Walk exercise will feel at home with the Shopper's Walk- aside from the fact that it's done in a grocery store with shopping baskets and not in a gym with weights.  If you don't know what a Farmer's Walk is, don't worry, this exercise won't make you look weird.  All you have to do is walk with good posture while carrying a basket on one side.  Simple enough right?  The difficult part involves trying to resist leaning with the shoulders, torso or crossing the feet in trying to counter the weight of the heavy basket.  Here's a more in depth how-to:

1. Keep the basket level. Grab the handle in the center or further from the center so that it won't tilt and jam into the side of the leg.  As the basket gets heavy, your deltoids will be tiring in an attempt to keep the basket away from the body.
2. Load the basket with groceries.  Milk and orange juice were the heaviest items in my basket.  Here are their weights in pounds and kilograms.
• Milk (1 gallon): 8.5 lbs or 3.9 kg
• Orange Juice (1.75 liters): 4.0 lbs or 1.8 kg
3. Walk with good posture: 
• Feet hip or shoulder width apart and pointing forward (parallel to each other).



Visually check your feet.  They might feel
like they're parallel when they're actually not.

• Pull shoulders back in line with the spine.  Subtle difference visually, but makes a world of difference to those with upper back pain.  People with tight or strong pecs relative to the rhomboids have a rounded shoulder posture.



Neutral (Good Posture) vs. Rounded Shoulder (bad posture)

• Maintain level shoulders- don't let the weight on one side throw off the shoulders

• Head above shoulders (forward or tilted down).



Neutral vs. Forward Head (bad posture)

4. Engage the core while walking.  The best way to engage the core is to brace as if someone's going to punch your abdomen from all sides.  Try not to only brace the six pack muscle.
5. Don't rely on locked the elbows.  As the weight of the basket increases, you'll be tempted to lock the elbows.  Keep them barely unlocked to relieve pressure.  Yes, your biceps will hate you for not locking them, but your elbow will thank you!
6. Alternate sides.

WHAT IT WORKS:
In addition to the muscles involved with walking, the major muscle of focus should be on the core.  To challenge the core, be sure to do step four!  Here's a quick list of muscles which will be worked by the Shopper's Walk:

• Transverse abdominis
• Quadratus lumborum & Obliques - helps lift pelvis, allowing the leg to swing.
• Trapezius & deltoids - Assists with keeping shoulder lifted and basket away from the body.

Kinesiological Approach To Bike Fit: Cleat Position

CLEAT POSITION:  There are four types of adjustments which can be made to a cleat.

1. Fore/ Aft:  

• FORE:  Positioning the cleat forward allows the ankle to move more freely, allowing for a smoother pedal stroke.  The trade-off is that this requires more ankle stability, calf strength and puts the rider at risk of developing quad dominance.
• AFT:  This position limits ankle motion.  This provides added stability to the ankle, allowing the calves to rest, but makes the rider prone to bouncy pedal strokes.  When switching from a forward cleat position to a rearward position, a lower saddle position is needed to compensate for decreased plantarflexion.
2. Lateral/ Medial:  The goal is to spread weight evenly across the foot side-to-side.
• LATERAL:  Shifts weight towards the outside of the foot (small toe side).
• MEDIAL:  Shifts more weight onto the medial side of the foot (big toe side).  Limits the maximum amount of external rotation available before the heel strikes the crank arm.
3. Rotation:
• EXTERNAL:  Since the drive side foot sits further away from center, this side typically needs more external rotation to increase glute activation.
• INTERNAL:  Aside from causing the knee to strike the top tube, greater internal rotation tends to increase adductor and quadricep activation.
4. Tilt/ Lift:  Lifts are used to correct leg length discrepancies.  Tilt shims are typically used for riders with ankle or foot instability.

BIKE FIT NEVER ENDS

Now that you know how cleat position can impact your performance, don't set it and forget it!  If you worked hard to gain ankle mobility and strength, don't forget to put your newly acquired abilities to use by adjusting your cleat position to harness your new powers!

TEST YOUR ANKLE MOBILITY
The amount of freedom you have in your cleat position is determined largely by your ankle mobility.  I listed each motion and the normal range of motion for each movement.

• Dorsiflexion (25 degrees):  Point the foot up.  Eversion naturally occurs with dorsiflexion.
• Plantarflexion (45 degrees): Point the foot down.  Inversion naturally occurs with plantarflexion.
• Pronation (Eversion 20 degrees):  Foot tilts so that the small toe lifts off the ground.
• Supination (Inversion 45 degrees): Foot tilts so that big toe lifts off the ground.

KNEE MOBILITY

• Flexion (120 degrees):  If you have tight quads, the ankles must be more flexible to compensate for this restriction.  If they're not, the pelvis will tilt side to side to compensate.
• Extension (0 degrees):  Reaching negative numbers simply means that your knees hyperextend.
• Internal Rotation:  Tight hamstrings, specifically the semimembranosus and semitendinosus will cause the foot the internally rotate.
• External Rotation:  Tight hamstrings, specifically the biceps femoris will cause the foot to externally rotate.  

Additionally, there are two types of undesireable knee movements that can occur in your pedal stroke.

• Valgus stress:  Forces that move the knee towards the midline.  Tight adductors.
• Varus stress:  Forces that move the knee away from the midline.  Tight hip external rotators.

vaLgus = L shape,
VARus = Knees move "var" away
Cheesy.. but it helped me remember what these terms mean!

WORK ON MOBILITY
Remember that POWER = Force * Distance.  Working on mobility and flexibility increases the distance variable, which basically means MORE power for minimal work.  There's no better reason to spend more training time on stretching!

ROTATION:
While many cleat manufacturers designed cleats to restrict rotation, research has found that giving the foot the freedom to rotate prevents overuse injuries such as IT band syndrome, patellofemoral syndrome, hamstring strains and calf strains.  Cleats should be set so that the foot has an equal amount of internal and external rotation from the forward position.

Here is a list of overuse injuries related to cleat rotation, saddle height/fore/aft and muscular imbalances:

• Patellofemoral Syndrome:  
• Excessive internal and external rotation.
• Saddles set too low and/or far forward.
• Muscular imbalances: Tight quadriceps & hip flexors and weak inner quadriceps & hamstrings.
• IT band syndrome:
• Excessive internal rotation.
• A seat height that allows more than 150 degrees of knee extension.
• Saddles set to far back may also cause IT band syndrome.
• Muscular imbalances:  Weak gluteus medius and hip abductors.
• Hamstring & Calf Strain:
• Excessive internal rotation
• Saddle set too high and back
• Muscular imbalances:  Tight quadriceps and weak hamstrings. 

TILT & LIFT:
Before even considering a shim, it is important to determine whether or not the rider actually has everted ("pronated") or inverted ("underpronated") feet.  The first place to look is the arch.  Although not as accurate as a mat loaded with pressure sensors, moistening the bottom of a foot and stepping on paper can paint a rough picture of the arch.  After determining the rider's arch, don't assume that the ankle will be pronated just because the rider has flat feet.  Check the ankle for eversion, inversion or neutral alignment (this would have already been done with the posture assessment).

Remember that the platform of the cycling shoe is rigid and any tilting will affect the entire foot.  This means that shims will affect the position of the ankle the most, but do nothing for the arch.  So even if the ankle is aligned properly, the rider may still experience foot pain because it was never addressed.  If an arch support is needed, the proper orthotic must be used.  Another option is to tape the foot for support.  Many times, correcting the arch will also correct the ankle, so double check to see if the shim is still needed. I recommend starting at the foot (orthotics/ tape) and then moving to the ankle (shims).

Another word of caution about using shims to tilt the cleat and "correct" a pronated or supinated ankle.  As mentioned in "Kinesiology 101: Ankle", eversion accompanies dorsiflexion and inversion accompanies plantarflexion.  If a shim is used to evert the ankle, the knee may move out of alignment when the ankle is dorsiflexed.  In a similar situation, if a shim is placed to invert the ankle, it may invert too much during plantarflexion.  Too much inversion or eversion will compromise the position of the knee and put it at risk for injury.

Before deciding on the steepness of the shim, assess the rider's ankling throughout the pedal stroke.  See how much dorsiflexion and plantar flexion the rider uses on and off the saddle.  After setting the shim, reassess the rider's cycling technique to make sure the knee is aligned.

With regards to leg length discrepancies, shims are very effective.  This can make a dramatic difference in the ride because the shorter leg will never need to "reach" from the hip whenever the leg approaches full extension.  If a shim is not available, lowering the saddle is another effective solution.  Although I haven't tried it, I think it would be possible to make a flat shim from extra garage supplies lying around in the garage.

REFERENCES:

1. Cosca, David, and Franco Navazio. "Common Problems in Endurance Athletes." Family Doctor. N.p., n.d. Web. 5 Dec. 2011. <familydoctor.org>.
2. Floyd, R. T.. Manual of structural kinesiology. 17th ed. Boston: McGraw-Hill Higher Education, 2009.
3. Holmes J.C., Pruitt A.L., Whalen N.J. Lower Extremity overuse in bicycling. Clinical Sports Medicine 1994;13:
4. Schwellnus, MP, and EW Derman. "Common injuries in cycling: Prevention, diagnosis and management." Department of Human Biology 47.7 (2005): 14-19. Print.
5. Timothy, Noakes, Schwellnus Martin, and Zyl Elize van. "A Review of the Etiology, Biomechanics, Diagnosis, and Management of Patellofemoral Pain in Cyclists." International Sport Medicine Journal 2.1 (2001): 1-36. Print.

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).

Training Program Design Breakdown

For any experienced fitness professional, the following principles should be a good review to make sure the training program is designed correctly.  If the following training principles sound new, applying these principles will definitely make a positive change to any program.

1. SAID Principle:  SAID stands for "specific adaptations to imposed demands" which means that what you do is what you get.  All training programs should be specific to the goal of the individual.  Does the individual need to work on strength, power, cardiorespiratory endurance, flexibility, mobility, agility or muscular endurance?  For example, a sprinter would not necessarily benefit from a program that focuses mainly on long distance running to improve muscular endurance.  A sprinter would need a program that focuses on strengh, power, flexibility and mobility.  After determining what component to work on, the metabolic demands of the activity must be known.  Does the activity require a lot of ATP-PC activity or more on the lactic acid and aerobic metabolic systems?  Finally, the movements used in strength training must also resemble the movements of the sport or activity.  For cyclists, they would benefit more from a plyometric squat (concentric phase only) than a plyometric split squat because the split squat fails to resemble the movement of the legs and feet on the pedals.  The closer the training program imitates the specific activity or sport, the chances are better that the program will produce positive results.
2. Overload:  The overload principle refers to the amount stress placed on the body.  For a positive training effect, the overload needs to be greater than what the body is used to.  For example, performing a work interval at a recovery intensity is a good way to progress no where.  There are four ways to provide overload.  Frequency, duration, intensity and volume can all be changed to make the exercise program more or less challenging.
• Frequency is the number of sessions trained per week.  By including 24 hours of rest in between session days, the max a beginner can train in a week is four days- a good reason to never miss a workout!  Once a strong athletic base has been built, seven days a week is possible with more opportunities to skip workouts if needed.
• Duration is the length of time spent on the workout(s).  There is usually an inverse relationship between duration an intensity.  As duration goes up, intensity usually goes down, vice versa.
• Intensity is the amount of effort required by the session.  This can be measured with a heart rate monitor, RPE or as a percentage of the maximal amount of weight an individual can lift for one repetition (1RM).  In aerobic exercise, intensity is often determined through percentages of maximum heart rate or target heart rates.
• Training volume is the total time spent exercising throughout the week and may be calculated by multiplying frequency by duration (3).  For example, training 7 days per week for 30 minutes every workout has a training volume of 210 minutes per week.  On the other hand, training 4 days a week for two hours every workout yields a training volume of 480 minutes.  It is important to be aware how much volume was designed into the program.  Overtraining and overuse injuries may occur by failing to pay attention to the rise in training volume.
3. Recovery:  To balance the principle of overload, the principle of recovery is absolutely necessary for allowing the body to recover and adapt to the demands it experienced after the training session or work interval.  Without a recovery period, the body will accumulate more damage than repair- a recipe for injury.  By allowing the body to repair damaged muscles/ fascia and replenish energy stores, this will ensure that the next training session can be performed at the same intensity or higher- better yet, there will also be a reduced risk of injury.  No pain, big gains!
4. Progression:  The amount of overload and recovery may change throughout a training cycle.  Progression is a way to determine if the program has too much or too little of overload or recovery.  The steploading method used commonly in periodized programs produces optimal progression (1,2).  In steploading, training load is progressively increased until every third of fourth session where the training load is decreased to allow for recovery and adaptations (1,2).
5. Variability/ Reversibility:  As the individual progresses throughout the training cycle, progression may begin to occur more slowly until a plateau is reached.  Once a plateau is evident, confirm whether or not the cause of the plateau is due to overtraining.  The principle of variability emphasizes the importance of varying the type of overload used in training.  In other words, try to avoid doing one type of exercise.  For example, competitive cyclists need strength, power, flexibility and endurance to become faster.  If the cyclist's program only focuses on bike-only exercises, a plateau will definitely occur as well as an increased risk of overuse injuries.  Although bike work is important, strength training and flexibility is key to preventing injury and correcting muscular imbalances caused by cycling.
6. Maintenance:  Once the desired level of fitness is achieved, maintenance becomes the main goal to ensure that the adaptations gained through training is not lost.  In order to maintain a level of fitness, intensity must be maintained.  Duration and frequency may decrease without losing the positive adaptations; although the amount of the decrease depends largely on the individual (3).  For most endurance athletes, a rapid loss of cardiorespiratory endurance can be prevented with a minimum of three sessions per week at 75% VO2 max (4).
7. Individualization:  Because of differences in gender, age, diseases, genetics, body type, stress, diet and amount of sleep, not everyone will adapt the same way to a training program.  With that being said, never use the same exact "one size fits all" program for everyone!  Some people may overtrain, plateau or even detrain to a same program.
8. Warm Up & Cool Down:  Like the SAID principle, the warm up and cool down must be specific to main exercise of the session.  For example, before a hard cycling interval on an upright bike, the cyclists should warm up preferable on an upright bicycle rather than a recumbent bicycle.

References:

1. Bompa, T.O.: Periodization: Theory and Methodology of Training. Champaign, IL: Human Kinetics (1999).
2. Freeman, W.H.: Peak When It Counts: Periodization for American Track & Field (3re edition). Mountain View, CA: Tafnews Press (1996).
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. Mickelborough, Timothy. "Training for Sport." Exercise Physiology. Health Physical Education and Recreation. Indiana University Bloomington, Bloomington. 10 Aug. 2010. Lecture.

What is the Core?

In an adult skeleton, there are about 206 bones (1).  Of the 206 bones, only five of them serve as an important skeletal structure that the core muscles press and pull against.  Unlike the thoracic spine, the five disks of the lumbar spine does not have ribs that provide it with additional strength, stability for posture, shock absorption and rigidity against impact.  To overcome this obstacle, the body has to rely on a network of muscles and fascia to take on the demands that both bone and muscle experience, this is the core.  Because the muscles of the core can move the spine through all planes of motion, the lumbar spine is more vulnerable to damage.  Any muscular imbalance will cause the spine to favor a dangerous posture and likely damage the lower back.


THE IMPORTANCE OF MUSCLE BALANCE:
The relationship between the muscles of the lumbar spine and the disks can be best interpreted as a guy wire system.  Imagine that the lumbar spine is a five story tower with muscles or "wires" that attach to both sides.  In normal conditions (see figure 1.1), the muscles of the lumbar spine keep the disks aligned correctly- both sides have equal tension.  In unhealthy conditions (see figure 1.2), the disks are pulled out of alignment due to unbalanced muscular strength. As shown on figure 1.2, the wires to the right overpowered the wires to the left and caused the tower to lean out of alignment.  In muscular terms, the wires to the right are now in a tightened position and the wires to the left are in a stretched position.  If no actions are taken to correct this imbalance, low back pain will usually occur.

Figure 1.2 Unbalanced

Figure 1.1 Balanced

Muscular imbalances may be caused by the following:

1. Poor posture for extended periods of time
• Example:  Driving, office jobs, watching tv, sitting at a table and waiting at an airport
2. Poor posture while lifting light or heavy objects
• Example:  Prepping and cooking food, reaching for objects above shoulder height, moving boxes and lifting suitcases/ luggage
3. Repetitive activities/ sports dominantly in one plane of motion.
• Example:  Running, cycling, swimming and rowing.
4. Poor posture during sports
5. Poorly designed weight lifting programs. 
• Example:  Only performing exercises to visibly improve rectus abdominis appearance ("six pack").

ANATOMY & FUNCTION OF THE CORE:
There is more to the core than the "six pack" muscle, the rectus abdominis.  In addition to the diaphragm and the muscles of the pelvic floor, there are about 16 muscles- a lot more than this if I were to include every intricate muscle.  If you feel comfortable with the anatomy of the core, skip onto the next section about core exercise design.


Starting with the deepest groups of muscles, there are eight muscles that directly affect the movement of the lumbar spine.  The first group of muscles is the erector spinae group.  This group is responsible for spinal extension and posture.  The second group of muscles is less well known probably because the name is not as easy to remember, the transversospinalis group.  These muscles are small and literally attach from vertebrae to vertebrae.  Their purpose is to provide stabilization of individual vertebrae and prevent excessive rotation, lateral flexion and spinal flexion.  The quadratus lumborum is in a group of its own because it is able to perform two entirely different movements of the spine, spinal extension and lateral flexion.  Through bilateral (at the same time) contractions, this muscle performs spinal extension.  If used unilaterally (one side only), the quadratus lumborum laterally flexes the spinal column and also lifts the hip upward. (4)


Due to its function, the middle layer is usually the most important core muscle group to focus on.  As a group, the muscles/ fascia form a box.  This layer is important because it contains the transverse abdominis, the muscle responsible for providing the compressive forces that takes off stress from the lumbar spine and provides a stable foundation for the upper and lower body to press and pull against.  If the transverse abdominis is weak, more stress is placed on the lumbar spine and the muscles of the extremity will have to work extra hard.  Why is this a problem?  In addition to the risk of low back pain, the increased demands on the extremities means that more stress will be placed on the joints above and below the core.


The outermost layer of the core is responsible for gross movement of the trunk and also provides additional compression.  This group consists of the rectus abdominis, internal oblique, external oblique, latissimus dorsi and the iliopsoas (hip flexor).

Deep layer:

• Erector Spinae - Spinal extension

• Iliocostalis, longissimus and spinalis

• Transversospinalis - Spinal extension, lateral flexion of the spine, rotation of the spine

• Interspinalis, Intertransversarii, multifidus, rotatores and the semispinalis group (thoracic) 

• Quadratus lumborum - Bilateral activation = spinal extension , Unilateral activation = lateral flexion of the spine

Middle layer (the box):

• Diaphragm - "The lid"

• Pelvic floor - "The bottom"

• The sides of the box

• Transverse abdominis - Flexes vertebral column/ compresses abdominal wall

• Quadratus lumborum - Spinal extension/ lateral flexion of the spine

• Multifidus - Spinal extension, rotates spinal column

Outermost layer:

• Rectus abdominis (connected by linea alba) - Spinal flexion, compresses abdominal wall and helps with expiration

• External oblique

• Bilateral - Spinal flexion & compresses abdominal wall

• Unilateral - Lateral flexion of the spine

• Internal oblique

• Bilateral - Spinal flexion & compresses abdominal wall

• Unilateral - Lateral flexion of the spine

• Iliopsoas

• Bilateral - Spinal flexion

• Unilateral - Lateral flexion of the spine

• Latissimus dorsi (Thoracolummbar Fascia)

FOUNDATION OF CORE EXERCISE DESIGN:

By knowing that the core is a group of muscles that works as one unit to stabilize the abdominal area, it is easier to understand why crunches and sit-ups are not effective core exercises.  These exercises target mainly one muscle rather than all of the core muscles at once.  Choose exercises that will make the core work hard to keep the spine positioned correctly.  Because core exercises directly affects the spine, risk of injury is greater; so be sure to consult a fitness professional to ensure that the exercises are performed with correct form.


Core Exercise Tip #1:  Learn how to activate the core and breathe at the same time.
If you noticed above, the majority of the core muscles are responsible for compressing the abdominal wall to provide a stable foundation.  This means that any exercise can become a core exercise as long as core activation is learned.  There are two methods that many use to activate the core, abdominal hollowing and bracing.  McGill stated that in terms of stabilizing the spine, bracing was more effective than abdominal hollowing or "centering", a common method used for yoga/ pilates (3).  Another study also found that bracing was a more effective method to stabilize the spine (2).  In order to brace effectively, I always pretend as if I was about to be punched from the front, sides and back of my abdominal wall at the same time.  While activating the core, remember to always breathe or else blood pressure will rise very fast!


Core Exercise Tip #2:  Choose exercises that require core activation to stabilize the spine throughout all planes of motion.
Because the core is responsible for maintaining good posture by preventing movements such as spinal flexion, extension, rotation and lateral flexion at the spine, it is important to challenge the core this way.  Exercises such as the half kneeling anti rotation is an excellent way to challenge the core through rotational forces.  To challenge the core in the sagittal plane, a popular exercise is the plank and variations on it.  To prevent lateral flexion at the spine, the farmer's walk is an excellent choice.


Core Exercise Tip #3:  Don't forget the lats!

Although it seems like it doesn't belong, the latissimus dorsi contributes to the stability of the core.  Because the lats are located at the core, they will provide additional stability for the deeper muscles to press against.

Resources:

1. Bryant, Cedric X., and Daniel J. Green. ACE advanced health & fitness specialist manual: the ultimate resource for advanced fitness professionals. San Diego: American Council On Exercise, 2008. Print.
2. Gambetta, V. (2007). Athletic Development: The Art and Science of Functional Sports Conditioning. Champaign, Ill.: Human Kinetics
3. McGill, S.M. et al. (2003). Coordination of muscle activity to assure stability of the lumbar spine. Journal of Electromyography and Kinesiology, 13, 353-359.
4. McKinley, Michael P., and Valerie Dean Loughlin. Human anatomy. Boston: Mcgraw-Hill Higher Education, 2006. Print.

Low Bone Mass in ROAD Cyclists and Ways to Fix it

It may come to a surprise that many professional road cyclists are at risk for osteoporosis.  Even with their amazing endurance and the ability to maintain very high power, being in a non weight-bearing position for extended periods of time is not conducive towards maintaining healthy bone mass density (BMD) (2).  In a study by Bryant et al, 30 professional road cyclist (~29 years old) were compared to 30 young healthy males of similar age.  When comparing BMD values from multiple sites, they found that professional road cyclists had a similar head BMD, but saw lower values in the following locations:

• Arms
• Legs
• Spine
• Pelvis
• Lumbar Spine
• Femoral neck (most affected site -18%)

Road cyclists who neglect strength training are at risk for osteoporosis and may already be osteopenic:
Another study produced similar results.  Smathers et al. measured total body, lumbar spine and proximal femur BMD in male competitive road cyclist and compared their values to age-/ body mass-matched controls.  Despite having at least 9.4 years of racing experience and 7-22 hours per week of training, the cyclist's t-scores indicated that 9% of the cycling group and 3% of the control group were classified as osteoporotic (5).  In terms of osteopenia, 25% and 10% of the cycling and control group, respectively, were osteopenic (5).

Greater Problem with Master Road Cyclists
Differences in BMD was even more prominent when master cyclists were compared to age matched controls.  In a study performed by Nichols et al, master cyclists with a minimum of 10 years of training who performed little weight-bearing exercise were measured at the spine and total hip.  Both sites were significantly lower compared to the age matched controls.  This study showed that although the master cyclist were highly trained and physically fit, they were still at risk for developing osteoporosis with advancing age (4).

Mountain Cyclists vs. Road Cyclists
I want to emphasize that decreased bone mass density was found only in road cyclist who performed little to no weight bearing exercises.  Mountain cyclist may not have to worry about low bone mass density.  In a study specific to mountain cyclists, BMD values at the proximal femur, lumbar spine and the total body were higher than the controls (7).  The sharp forces experienced through mountain biking may provide the stimulus necessary to cause bone to adapt.

Runners vs Cyclists

Running was associated with increased bone density, especially in the leg (6).  Again, cycling was associated with a mild decrease in BMD of the total body and lumbar disks L1-L4 (6).  The results show that high impact activities such as running, plyometrics and power exercises may generate loads several times the body weight- enough strain to stimulate adaptation of the bone (2,6).

Ways to Improve BMD
Many road cyclists have a "ride more" attitude, and will avoid strength training, fearful that the fatigue will cause them to lose riding time.  In reality, a cycling program that includes heavy weight lifting actually improves endurance in elite athletes (8).  As I described in a separate post about lifting weights to improve endurance, heavy weight lifting recruits both slow and fast twitch muscle fibers.  This is why strength training alone can produce significant improvements in VO2max and muscular endurance.

Implement these points to your cycling program for a healthy BMD:

• Include heavy weight lifting (at least 8 RM) or any load that is greater than what's encountered on a daily basis (2).
• Perform strength exercises in a standing posture such as squats, lunges, long jumps, box jumps, etc.
• Use free weights or a weighted vest at 7-15% body weight (2).
• Emphasize exercises that improve muscular strength and power (2)
• Participate in high-impact, group exercise classes (aerobic, boot camp, zumba, etc.)
• Plyometrics.  Studies have shown that simple jumping exercises may increase bone mass, especially at the hip (9,10,11,12).

If spine BMD or bone status are unknown, see these exceptions to the suggestions above:

• Avoid heavy loads (>10% body weight) (2).
• Avoid high impact plyometrics (>2.5 times body weight)
• Avoid loads greater than 8RM

References:

1. Applied anatomy and biomechanics in sport. New York: Blackwell Scientific Publications, 1994. Print.
2. Bryant, Cedric X., and Daniel J. Green. ACE advanced health & fitness specialist manual: the ultimate resource for advanced fitness professionals. San Diego: American Council On Exercise, 2008. Print.
3. Campion, F., A.M. Nevill, M.K. Karisson, J. Lounana, M. Shabani, P. Fardellone, and J. Medelli. "Bone Status in Professional Cyclists."International Journal of Sports Medicine Sep. 2010: 511-515. Print.
4. Nichols, Jeanne, Jacob Palmer, and Susan Levy. "Low bone mineral density in highly trained male master cyclists."International Osteoporosis Foundation and National Osteoporosis Foundation July 2003: 644-649. Print.
5. Smathers, Aaron, Michael Bemben, and Debra Bemben. "Bone Density Comparisons in Male Competitive Road Cyclists and Untrained Controls."Medicine & Science in Sport & Exercise Feb. 2009: 290-296. Print.
6. Stewart, Arthur, and James Hannan. "Total and regional bone density in male runners, cyclists, and controls."Medicine & Science in Sports & Exercise Aug. 2000: 1373-1377. Print.
7. Warner, S.E., J.M. Shaw, and G.P. Dalsky. "Bone mineral density of competitive male mountain and road cyclists."Bone Jan. 2002: 281-286. Print.
8. Hickson R., Dvorak B., Gorostiaga E., Kurowski T. & Foster C. (1988) Potential for strength and endurance training to amplify endurance performance. Journal of Applied Physiology 65, 2285-2290.
9. Bassey, E.J. & Ramsdale, S.J. (1994). Increase in femoral bone density in yound women following high impact exercise. Osteoporos International, 4, 2, 72-75.
10. Bassey, E.J. et al. (1998). Pre- and postmenopausal women have different bone mineral density responses in the same high-impact exercise. Journal of Bone Mineral Research 13, 12, 1805-1813.
11. Heikkinen, R. et al. (2007). Acceleration slope of exercise-induced impacts is a determineant of changes in bone density. Journal of Biomechics. 40, 13, 2967-2974.
12. Winters, K.M. & Snow, C.M. (2000). Body composition predicts bone mineral density and balance in premenopausal women. Journal of Women's Health and Gender-Based Medicine, 9, 8, 865-872.

Weight Training Methods for Muscular Endurance

While lifting for 12-15 reps at approximately 60% 1RM is great for developing localized strength and endurance within specific muscle groups, there are other methods just as effective at improving muscular endurance.  If you lift regularly with minimal to no professional supervision, I recommend avoiding method #1, heavy weight training.  Same recommendation follows for variable load training unless you decrease the load. 

1. Heavy weight training
• 80-90% 1RM, 4-8 repetitions.
• 100% 1RM produces the greatest improvements in both endurance and strength, but greatly increases risk of injury.
2. High repetition training
• 30-50% 1RM, 30-50 repetitions, 3-4 sets
• May be used to develop power.  Reps and sets may stay the same, but use a load of 30% 1RM for optimal power development.  Full rest between sets is required.
• A variation of this set to a time limit (interval training)
3. Variable load training
• Combines both methods.  Progressively lower loads are lifted consecutively with little to no rest.  Repetitions depends on the load.
• First load focuses on strength- 66% 1RM or higher
• Last load focuses on lactic acid production- 30-50% 1RM

1. HEAVY WEIGHT TRAINING:  Contrary to popular belief, lifting heavy weights for a few repetitions will not just improve muscular strength, it will also improve endurance.  Lifting heavy weights will improve endurance because all motor units must be recruited to complete the lift, that means both fast and slow twitch muscle fibers will be activated (2,7).  For this reason, it is widely accepted that there is a strong relationship between muscular strength and endurance (1,2).

I was skeptical about this method at first, but it made sense after I realized that the physiological changes that occur with heavy weight lifting are similar to that of endurance training.  The structural changes that occur with heavy weight training include increased number/ size of myofibrils, number of actin/ myosin and the size/ strength of tendons, ligaments and connective tissue (2,4).  In addition to these anatomical changes, anaerobic metabolism also improves through increased levels of creatine phosphate, glycogen and creatine phosphokinase (4).  All of these changes allow the muscle to operate with less effort to do the same amount of work.

To make it easier to understand how effort is reduced, I calculated two realistic changes in 1RM that could occur with heavy weight lifting.  Let's say that a cyclist needs to produce 50 pounds of pedal force to maintain a hard pace.  If the cyclist had a 1RM of 200 pounds, then it would take 25% of maximal effort to maintain that hard pace.  After spending time with heavy weight lifting, the cyclist improved the 1RM to 230 pounds.  Next time the cyclist tries to maintain that hard pace, it will feel easier because instead of using 25% of maximum, only 21.7 % is needed to maintain that pace.

• Initial maximal strength:  1RM = 200 lbs / 1 repetition
• Cycling requirement:  50 lbs / pedal stroke = 25.0% of maximum
• Improved maximal strength:  1RM = 230 lbs / 1 repetition
• Cycling requirement:  50 lbs / pedal stroke = 21.7% of maximum

Being able to operate at a lower percentage of maximum is a clear advantage that endurance athletes can take advantage of.  To reap the benefits of this method, a weight greater than 66% of 1RM must be used (3).  For the greatest possible improvement in strength, use 100% 1RM (2).  If you choose to lift 100 percent, please be smart and get a spotter!

2.  HIGH REPETITION TRAINING:  High repetition training or HRT involves three to four sets of lifting relatively light weights (30-50% 1RM) anywhere from 30 to 50 times.  This is a popular method for increasing muscular endurance because the training effects are more obvious and easier to understand.  High repetition training improves muscular endurance through four mechanisms different from the method above:

1. HRT produces more lactate than the levels found in competition
2. Improves the individual's tolerance to the fatiguing effects of lactate
3. Promotes local circulation to the working muscle group(s)
4. Enhances metabolism and other by products

Of the three mechanisms, one and two are the major reasons why it's important to implement this type of training to a program.  Greater tolerance to lactate is advantageous to anyone who needs to work at high intensities for a long time.  This will translate to better performance in competition and training.  I also wanted to mention that the load recommended for this type of training is very similar to the optimal load for maximal power training (approximately 30-45% 1RM) (2).  For the greatest improvement in power, studies have found that 30% of maximum will optimally improve power (5,6).  To specifically improve power-endurance, the repetitions may also be performed explosively.

Another variation of this method involves completing the greatest number of repetitions within a set time.  For example, a 5k runner will likely run 400 meters in 50 seconds repeatedly.  This variation might sound familiar because it is essentially "interval training."

3.  VARIABLE LOAD TRAINING:  This method combines the best of both worlds that heavy weight training and high repetition training can offer.  Because methods one and two produce similar improvements in muscular endurance, this type of training is an excellent way to reap both of the benefits (2).  To perform this type of training, a number of progressively lighter loads should be performed consecutively with little to no rest.  The first load(s) must be higher than 66% 1RM to improve maximal strength gains (3).  The final load(s) should be 30-50% 1RM to increase lactic acid production and improve tolerance to the effects of lactic acid.  Successfully lifting all of the loads marks the end of the first set.  See the sample program below.

• 10 repetitions/ 80% 1RM
• 12 repetitions/ 60% 1RM
• 15 repetitions/ 40% 1RM
• 10 repetitions/ 30% 1RM explosive

References:

1. Anderson T. & Kearney J. (1982) Effects of three resistance training programmes on muscular strength and absolute and relative endurance.  Research Quarterly for Exercise and Sport 53, 1-7.
2. Applied anatomy and biomechanics in sport. New York: Blackwell Scientific Publications, 1994. Print.
3. McDonagh M. & Davies C. (1984) Adaptive response of mammalian skeletal muscle to exercise with high loads. European Journal of Applied Physiology 52, 139-155.
4. 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.
5. Kaneko M., Fuchimoto T., Toji H. & Suei K. (1983) Training effect of differing loads on the force-velocity relationship and mechanical power output in human muscle. Scandinavia Journal of Sport Science 5, 50-55
6. Moritani T., Muro M., Ishida K. & Taguchi S. (1987) Electrophysiological analyses of the effects of muscle power training. Research Journal of Physical Education in Japan 1, 23-32.
7. Schmidtbleicher D. & Haralambie G. (1981) Changees in contractile properties of muscle after strength training in man. European Journal of Applied Physiology 46, 221-229.