Happy Thanksgiving!

Hope you all have a great Thanksgiving Day.  Did you get a ride in today before the big dinner feast?  I did.  Now I won't feel as guilty downing all the food/drink.  Don't forget, the average Joe gains 5-10 lbs. from Thanksgiving to New Years day.  For me, it's a time of year I start watching what I eat because it's too easy to start drinking and eating too much.  Every where you go over the Holiday's there's food- mostly junk food.  So, riders beware!  Don't forget to get a long ride in this weekend.  It's supposed to be mild temps (50F ish).

PowerCal vs. Computrainer Power Output

Let me just say this before I begin, this post was not intended to compare the merits of a $100 power meter/HR monitor made by Power Tap to that of a $1500 power meter made by Racermater aka Computrainer.  There is no comparison.  What it's intended to do is show/highlight the PowerCal for what it is.  That is, it's an inexpensive tool to get you into the "power meter" world without taking a 2nd mortgage out on your home.  Just like you can go to a store and buy a $100 micrometer vs. $1000 micrometer, they both do the same job..measure things.  It's just that one does it with better accuracy/precision than the other.  Naturally, the higher the price the more accurate.  Same applies with power meters.

From the research that I've done, I read/heard the PowerCal power meter/HR monitor has better reliability (closer accuracy) with longer steady-state efforts rather than shorter intervals.  So, I set out to see if this was true, and lo and behold- it is/was.  Granted, this is not a scientific study and the sample size is not large enough to give it any statistical significance.  Nonetheless here it is.  See Chart below:

You can see that as the intensity increases (L1 thru L4) the change in watts (delta) between the Computrainer and PowerCal increased.  I can only assume that's because of the short 5 minute intervals.  So, I decided to do a longer interval at L4 (20 minutes instead of 5 minutes).  You can see that the delta decreased from 30 watts to 10 watts.  That is, the PowerCal was more accurate at longer steady-state intervals.  I tried to maintain the target watts of 225w at L4 but I could only muster 205w.  Just not on my A-game since I rode hard on Tuesday night and it's currently Thursday night.  Yeah, I know, it's 2 days..but I'm almost 60 and I seem to need 3 days rest before hard workouts rather than 2 of yesteryear.

I'm really happy with my PowerCal power meter/HR monitor for $100.  It does what it was intended to do and that is get you in the ballpark of the power meter game.  As I said before, it's not intended to compare with the more expensive power meters on the market, but it will get you in the game/ballpark..and that's what I wanted.  If I want better accuracy I'll use one of my more expensive power meters on a ride- that has better accuracy.

BTW, I own 2 computrainer power meters at $1500 ea. (one is Lab quality), an iBike Pro power meter at $400, 2 Power Tap power meter hubs at $700 ea.  And, now a PowerCal power meter/HR monitor.   That's over $4000 worth of power meters. So, it's not that I don't have any other power meters or I can only afford a $100 power meter.

Power ON!  Coach Rob

Blood Pressure & Pulse

One of the reasons why I ride is to stay healthy.  I don't have to tell you that eating healthy and exercising is the key to good health- that and good genetics.  Actually, it's better to have good genes than anything else.  I've known many people to die early on in life from nasty diseases such as cancer, heart disease, etc. despite being in great physical shape.  We have no control over the hand we were dealt re: genes, so it is what it is and you are what you are.  For the things we do have control of- why not eat healthy and exercise?

As far as your heart goes, it's wise to keep track of your blood pressure and your pulse.  I like looking at pulse as well as heart rate because it gives me a good indication of my current fitness. i.e. normally the lower the pulse the better shape (in younger people).  There is a condition called bradycardia and it usually affects older adults (>65).  Bradycardia is a deterioration of the electrical system of the heart.  Bradycardia lowers the pulse rate in older adults.  There are also many drugs out on the market place that lower pulse rate.  When I'm not in shape, my heart rate/pulse is normally around 65bpm.  When I'm in-shape it's generally in the mid to high 40s.  Currently my resting pulse is 47bpm.  This past May when I was out-of-shape my pulse was 65bpm.  So, in 5 months I was able to lower my pulse (resting heart rate) almost 20 beats per minute due to eating healthy and exercising.

What's a normal heart rate/pulse?  According to the Mayo Clinic anything from 60-100bpm is considered normal.  (Although to me, anything over 80 seems high).  Generally, a lower heart rate at rest implies more efficient heart function and better cardiovascular fitness. An elite athlete might have a normal resting heart rate closer to 40bpm or even in the high 30s.

So, what's a normal blood pressure?  According to the American Heart Association the recommended or normal blood pressure is 120/80, read one twenty over eighty.  The top number is the systolic blood pressure measured in millimeters of mercury (mm-Hg).  Systolic pressure is the pressure that the blood exerts on the artery walls when your heart pumps.  The bottom number is the diastolic pressure measured in mm Hg.  Diastolic pressure is the pressure that the blood exerts on the artery walls when your heart is resting or in-between beats/pumps.  Here's a chart from the AMA:

My current blood pressure and heart rate is: 107/71 mm-Hg with a pulse of 47bpm.  That's with taking no prescription medication.  I take my blood pressure and heart rate at least once per month.  I try to make a habit of checking it once per week.  A lot of the CVS/Rite Aid pharmacies have blood pressure machines/monitors that are calibrated regularly.  I used to use them but I bought one for home instead.  It's made by Omron and is one of the most reliable home blood pressure monitors on the market (according to my research).  It takes 3 readings/tests and gives you the average.  It also stores the information in the unit for future comparison.  I'm not sure of the price but I think it cost $100.  Yes, it's a little pricey but with the higher price you get higher accuracy/reliability.  I don't calibrate the unit but I do compare the readings with the local pharmacy blood pressure monitors to make sure it's comparable/in-line.

Is high blood pressure really a big deal?  I think so.  Here's a pictorial of what high blood pressure can do to your body:

Vision Loss- High blood pressure can strain or damage blood vessels in the eyes.

Heart Attack- High blood pressure damages arteries that can become blocked and prevent blood from flowing to tissues in the heart muscle.

Kidney Disease- High blood pressure can damage the arteries around the kidneys and interfere with their ability to effectively filter blood.

Sexual Dysfunction- This can be erectile dysfunction in men or lower libido in women. 

Heart Failure-The increased workload from high blood pressure can cause the heart to enlarge and fail to supply blood to the body. 

Stroke- High blood pressure can cause blood vessels in the brain to burst or clog more easily. 

Next time you're in the pharmacy (or doctors office) get your blood pressure taken and ask what your pulse is.  Or better yet, buy a blood pressure monitor for your home.  I think it's worth it.  Until then, eat healthy and keep riding your bike.

Power ON!  Coach Rob

Bike Light & Battery

A few posts ago I told you I bought a 5000 lumen 2x Cree XML bike light, battery and charger for $22.   https://www.amazon.com/gp/product/B00F372QSE/ref=od_aui_detailpages00?ie=UTF8&psc=1   Hard to believe huh?  Well, it was hard to believe because the 4400 mAh battery that came with the light could not power the light on the med setting for 1.5 hrs.  So, I was in search for a new battery that would last at least 1.5 hrs. on medium power which projects about 500 lumens, not 5000 as advertised.  Well, I found one for $15 and the best part is, IT WORKS!  Here it is:
https://www.amazon.com/gp/product/B00AAQOV5E/ref=od_aui_detailpages00?ie=UTF8&psc=1

The Mfg. claims it's a 6600 mAh capacity battery.  It could be.  I ran my light on medium setting last night for 1.5 hrs. and the bike light showed a minimum of 80% power left in the battery at the end of the ride.  That's pretty damn good if you ask me.  The only thing I didn't like about the new battery is that the coax end connector didn't have threads on it so that the lights coax connector could screw onto it providing a waterproof secure connection.  So, what I did was cut the connector off the 4400 mAh battery that had threads and swapped it out with the 6600 mAh.  It took me 20 minutes to solder and tape the connector on.  The best part is, it's now secure and waterproof.  There's an internal o-ring at the end of the bike light connector.

For $37 you've got a "waterproof" high power LED light, battery and charger that rivals an LED light that cost over $200 just 5 yrs. ago.  Plus, it's smaller and a lot lighter than bike lights of yesteryear.

Power ON!  Coach Rob

Why I ride!

There's a lot of reasons why I ride: to keep in shape, to get outdoors, because I like it, etc.  Another reason is because I like the competitive nature..whether it's organized racing or just out on a group ride for fun.  Last night it was the latter.  I was on a group night ride for fun.  The ride was advertised as a B/C ride but the group that showed up last night was mostly "B" riders.  A "B" rider on a recreational club ride would be synonymous with a USA Cycling Cat 5 group race (which are mostly beginner racers).

Whenever I ride with a group, I always size up the strong riders at the beginning of the ride.  I can normally pick them out- for the most part.  At the beginning of each ride I normally "sit-in" and warm up and conserve energy because I know I'm going to be pulling (out front) for at least 1/2 the ride.  Last nights ride was 1.5 hrs. long with approximately 1 hour of  steady riding.  The other 1/2 hr. is spent walking over bridges, stopping, slowing, etc.  Of that 1 hour steady riding, I'd say I'm riding in the L3/L4 (sweet spot) zone and L4 (threshold) zone.  When one of the strong riders pass me and go out front and try to separate themselves from the pack, I'm the first one on their wheel.  I don't like anyone getting away.  That's what happened last night on the PA side of the ride.  I was out front pulling at 16.5 mph and one of the strong riders passed me, so I jumped on his wheel.  We were now averaging 17.5 mph.   BTW, riding at 16.5 mph on a heavy mountain bike on the mud/gravel is probably equivalent to riding at 22 mph on a light road bike on asphalt. You can see from the graph below, I wasn't utilizing any more power and my heart rate didn't increase any more than when I was going 16.5 mph pulling out front vs. drafting at 17.5 mph.  Ahh, the beauty of the draft.

On the NJ side of the ride, the same thing happened.  Except the guy that passed me was sitting in the back for 3/4 of the ride. i.e. conserving energy.  That kind of pissed me off.  The guy doesn't share in any of the pulling, and then when everyone else is tired, he pulls away and separates himself from the pack.  I tried to reel the guy in by myself but every time I got close he pulled away.  I tried to recruit the guy behind me to help me pull and reel him in but the guy just didn't have enough gas left in the tank.  That's when two more riders a strong woman rider (Nora) and some other guy got in front of me and we chased him down.  You can see we were averaging 18+ mph at the end of the ride.  We came within 50 yds. of the guy when we finished.  It was fun chasing him down.  I know he knew we were gaining on him.  At the end of the ride, I  saw the guy in the parking lot (he was an older guy like me) and I told him, "we almost got you, good riding".  He smiled, he knew we almost caught him at the finish.  I was still kind of pissed that he sat in for 3/4 of the ride though and then when everyone was tired he decides to break-away.  Here's the graph of the final chase:

Anyway, if you want to know (one of the reasons) why I ride, that's why.  Good Fun!

Power ON!  Coach Rob

IF and TSS

There's a couple metrics worth looking at after a ride and they are Intensity Factor (IF) and Training Stress Score (TSS).  I'll define each:

IF (Intensity Factor)= NP/ FTP

where: NP= Normalized Power (watts)
           FTP= Functional Threshold Power (watts)

Normalized Power (NP) is an estimate of the power that you could have maintained for the same physiological "cost" if your power had been perfectly constant, such as on an ergometer, instead of variable power output.

Functional Threshold Power (FTP) is your "hour power".  That is, the maximum sustained average power for 1 hour.  This can be estimated by performing a 20 min TT and multiplying the max sustained average power for 20 min. by 95%.

Example:

I rode for 1.5 hrs. and my Normalized Power for the ride was 230w.  My FTP is 220w.  Therefore, IF= 230/220= 1.05   BTW, that's a pretty intense ride/workout.  Normally, tough workouts are around the 0.75-0.85 mark.  When I see an IF over 1.0 I'm suspect of the NP or FTP, or both.  I think in this example, the NP was too high since I know my FTP is definitely 220w.

TSS (Training Stress Score)= can be manually calculated or determined by an algorithm inside your bike computer or software that looks at the power zones you ride and time you ride in those zones.

Example:

My ride consisted of 30 minutes in L2 Zone, 1.5 hr. in L3 Zone and 1 hr. in L4 Zone.  

By definition, an TSS of 100 is equal to riding at your FTP for one hour.  

L2 (1.3 weight factor) x 30 min= 40 points
L3 (1.5 weight factor) x 90 min= 135 points
L4 (1.7 weight factor) x 60 min= 100 points

Training Stress Score (TSS)= 275 points  BTW, that's a pretty hard ride/workout for 3 hrs.  And, that's NOT the exact weighting factor that's used to compute TSS but you get the idea.

Power ON!  Coach Rob

Rolling resistance- revisited

I made a post a year or two ago on rolling resistance and how different mountain bike tires have different coefficients of friction based on tread pattern.  But, what I didn't mention is how tire pressure affects rolling resistance (generally the higher the pressure the lower the coefficient of friction between the tire and the road due to less tire contact with the road) not to mention the road surface. i.e. how rough it is.

After analyzing one of my post rides the other day, I was wondering why I was putting out more watts (power) on my mountain bike but my average speeds haven't been increasing.  That's because it's been very wet/cold recently and the ground has softened up on the tow path upon which I ride.  The tow path is comprised of dirt, gravel, leaves (lot of them lately), chunk rock, etc.  When it gets wet, the dirt turns to mud and the gravel mixes in with the mud and the leaves.  Thus, a softer surface to ride on.  I'm not sure what the difference is in watts between a soft tow path surface and a hard surface but I'll guess and say it's close to 10% or 20 watts at 200+ watt output.  Here's a table (below) with road surface coefficient of frictions and you can see that concrete has twice as less friction than asphalt does.  And, a rough paved road (I'm assuming something like chip seal) has 4x the friction that a smooth concrete road has.  So, you can imagine what the difference is between hard dirt and soft mud.

So, what does all this mean?  A higher coefficient of friction between the tire surface and the road surface means less speed for a given power output.  How much depends on a lot of things: road surface, bike tire rubber composition, bike tire width, bike tire tread pattern, bike tire sidewall stiffness, tire pressure, road surface temperature, etc.

Power ON!  Coach Rob

W prime (W')

Since I'm using Golden Cheetah software more often these days, I came across a metric called W prime, written W'.  I think it's a really neat/cool metric that wasn't and probably still isn't available in Training Peaks Software WKO+ 4.  It's new to me, that's for sure.  Before I tell you what W' is all about, you first must understand what CP (Critical Power) and what FTP (Functional Threshold Power) are.  Let's start with the latter.  FTP is your "hour power".  That is, it's your maximum sustained average power output in 1 hour in watts.  It's your average sustained power during a 40k TT.  Another way of determining your FTP is to do a 20 minute TT and find your maximum sustained average power.  Then, take 95% of that value and that's your FTP.  Critical Power (CP) is synonymous with FTP.  To find your CP do a 3 minute, 5 minute and 10 minute Time Trial with a Power Meter.  Or, do a 3 minute, 8 minute and 14 minute Time Trial which I heard is a little better for plotting.  Plot the power (3 pts.) versus duration (time).  Your CP, in watts, is where the line levels off.  You'll need a curve fitting software program to properly plot the graph and find your CP.  i.e. hyperbolic curve fit.  Want an easier way to compute your CP?  Download Golden Cheetah software and use their CP and W' Estimator.  See graph below:

Now, the amount of work that you can do above your CP, shown by the red hatched lines above, is your W'.  It's a fixed amount.  If you're a math geek, and you want to calculate the actual W' value, all you have to do is find the equation of the CP line and integrate (using calculus).  How quickly that fixed amount lasts is dependent on how hard you go above your CP and if you get any rest or breaks.  Go hard above your CP and you're not going to last long.  Go easy above your CP (say 250w in the graph above) and you'll last longer than if you went hard (say 300w in the graph above).  If you get a chance to recover during your ride, or take a break, it will replenish the W'.  How much it replenishes depends on many things such as the amount of time you recover, the power you recover to, etc.  Sooner or later though, whether you go hard or easy above your CP you're going to bonk/crash/run out of gas.  The value of W' where you start to crash and burn is around zero (0).  The units for W', or sometimes labeled W'bal, (balance) is in kiloJoules (kJ).   How long you can keep up the power at W' varies.  How negative a value you can have for W' varies too.

Here's a stress graph (from Golden Cheetah) showing W' for my latest ride today:

Not sure why Golden Cheetah gave me a W'bal of 20 kJ to start with.  I suppose it's based on my FTP of 220 that I entered into Golden Cheetah.  The segment of my ride highlighted in red is a 3 mile Time Trial on my Mountain Bike on the Tow Path.  You can see I started out a little hot, close to 300w, and backed it down to about 250w.  I should have done this TT fresh, if I wanted a personal best time, but I had just ridden 8 miles prior.  Nonetheless, you can see my W'bal plummet because 250w is definitely above my FTP or CP of 220w.  In fact, W'bal went negative at the end of my TT.  Was I exhausted at W'bal=0, hell yeah, but you could see I still had about 1.5 miles to go.  So, at 250w (30w above my FTP) it only took about 5-6 minutes before I was near 0 W'bal.  It doesn't take long.  Lessons learned, if you want to do a TT do it fresh and don't start out too hot (rookie mistake).  You can also see that my W'bal didn't start to recover until I walked over the bridge from Bulls Island, NJ to the PA side.  The PowerCal HR monitor/meter showed 100w when in reality I wasn't even on the bike.  I was walking my bike across the bridge because of the heavy pedestrian traffic.  Anyway, that's W'bal and I think it's a neat/cool metric for post-ride analysis.  Probably even better for post-race analysis.

Power ON!  Coach Rob