C2 vs. Assault Bike Calibration

It’s been a while since I updated this blog, but recently I did some testing at CrossFit Ignite on how to come up with equivalent WODs for those who want to or need to use the Assault Bike / Airdyne instead of the Concept2 rower. Here’s what I found, which corroborates the findings in this article. FYI: Set the Assault Bike to measure meters vs. miles for distance.

  1. Common level of effort can be reached by using the watts setting on either machine.  E.g. if level of effort is supposed to be 75% – you can feel what 75% is like on the C2 using the watts setting, and then go onto the AB and pedal at a similar watts level.  I tested at:
    • 200 watts – which is about 1000 cal/hr or 2:00/500m pace on the C2 – this is the range where most people will be working for most WODs.
    • 385 watts – which is about 2k pace for me on the C2.
    • Max – which is >750 watts on either machine.
  2. Rule of thumb for anything longer than 250m/10cal all-out sprints:
    • Multiply C2 distance by 2 for Ae.  E.g. 500m on C2 equals 1000m on AB in the same amount of time.
    • Multiply C2 calories by 0.5 for AB.  E.g. 50 cals on C2 equals 25 cals on AB in the same amount of time.
  3. For anything up to 250m/10cal intervals at all-out sprint intensity (>750 watts):
    • Distance rule of thumb is the same.
    • Calories become 1:1 – so 10 cal intervals on the C2 are also 10 cal intervals on the AB – but this is only true if you are revving the AB to absolute max. 
  4. I don’t know why the calories even out at high intensities. There is no way of knowing the differences in how each machine even calculates this. In general it’s possible to maintain a higher average wattage on a bike than on a rower because the cadence is much higher on the bike, although the absolute max attainable wattage is similar on both machines. My theory is that there is a limit to how fast a human can move arms and legs, and you reach this limit faster on the AB due to the higher cadence and shorter range of motion, so at a certain point you can pour more force into each stroke (calories) without being able to move the flywheel much faster (distance).

 

Advertisements

IRA Heavyweight Grand Final = lesson in rowing physics

The Intercollegiate Rowing Association (IRA) national championships took place this past weekend at Lake Natoma, near Sacramento, CA.  One of the big questions was whether the University of Washington, which had swept all events at the NCAA womens’ championships a couple of weeks ago, would also sweep all of the men’s events at IRAs.

Yale, the most dominant crew in the East, led at the start and by as much as a length through the middle of the race.  The question was whether they could withstand the Husky sprint.

They did, by .069 seconds.  This photo illustrates why.

The boats are basically even but Yale (background) is approaching the finish of their last stroke while Washington (foreground) is still mid-drive.  While both crews are going really fast (sub-5:30 for 2k), boats do not maintain a linear speed in rowing, but accelerate and decelerate during each stroke as power is applied and the combined body weight of the crew moves on sliding seats relative to the hull.  Yale is about to enter the fastest portion of the stroke where all the power has been applied, the blades come out of the water, and 8 200-lb. bodies slide to the stern, which due to Newton’s laws means the hull surges forward at its fastest speed.  Washington is still halfway through the drive, meaning that the force applied to the blades is being transferred through the footplates in the sternward direction, and the “rebound” from that force has not yet happened.

This means that within the next split second, Yale’s boat will surge forward before Washington’s, and that makes all the difference when the margin is literally the blink of an eye.  For CrossFitters who have never been in a boat, try rowing on a dynamic ergometer or a C2 on sliders to feel this effect.

Congrats to both crews on an amazing performance, to Cornell for winning the lightweight men’s championship, and to Stanford for winning the lightweight women’s championship, and to Washington for winning the overall points trophy.  Congrats to my alma mater Dartmouth for winning the Chapman trophy for the greatest improvement in points year over year.  Thanks to Row2k.com for great coverage as always!

Croker Arrow S40 Sculls – First Impressions

I mean to post this a while ago, but here goes.

At the end of last fall season fall I traded in my Croker S4 Superlights for new Arrow S40s.  It was time to replace the collars on my existing oars anyway, and I had talked to Greg Doyle about the anticipated S40 model, which combines a standard-modulus carbon shaft with the Arrow blade.  I had used the Arrow S39s (high-modulus) at Red Bull High Stakes, and they were so light that I felt like I was rowing with matchsticks on a windy day, so I wanted to try the heavier model with standard stiffness.

Bottom line:  Love ’em!

  1. Blade grip on the water is outstanding, and much, much better than the S4 Slick blade.  The lock on at the catch is so soft and quick that it reminds me of rowing with Dreher macon blades “back in the day,” to the point where I have to double-check to make sure I am not rowing it in.   With the Slicks, I would sometimes have the blade start to slip during the middle of the drive in rough conditions or when I was rowing poorly, but the Arrow blades are rock solid.  This has made it easier to catch with the speed of the boat, maintain a fully buried blade through the finish, take it out square.
  2. Blade weight is noticeably heavier, but I like this.  In the single, stability out of the water is improved at the cost of 150 grams of weight – which is a tradeoff I’m willing to make.  I have a much better sense of a solid platform with squared blades at max extension before the catch.  They also create less drama when I clip an object in the water with my blade on the recovery such as a buoy or log.
  3. Aerodynamics are much better.  I row on a long, narrow venue that can sustain pretty high winds before the water starts whitecapping, so I sometimes row in winds that would call for an ergo day on a lake with more fetch.  The S4s had a tendency to “lift off” on the recovery when hit by a sufficiently strong quartering head gust.  The Arrows are again rock solid – I have not yet had a wind-induced missed catch.

I realize that oar selection is a matter of personal preference.  For me, the Arrow S40s are a clear upgrade over the S4 Superlights.

The official descriptions are here:  http://www.crokerusa.com/sculling-oars

You can also use this nifty tool from Row2k.com to compare the Arrow and Slick blade shapes:  http://www.row2k.com/features/980/row2k-Blade-Comparator/

Coriolis Force Effect on Rowing and other Sports

This is a fascinating study on how the Coriolis effect may impact various sports…I’ve never thought about this before.

In rowing, the study states that it may take up to 7.5% of propulsive force to overcome up to 40m lateral displacement over a 2K race.  That is potentially a huge wildcard when you see elite finals being decided by a fraction of a second such as in Rio.

It would be interesting to see if there’s any potential correlation on championship times at high/low latitudes, or for example if rowers who train at relatively high latitudes (NZ? GB?) experience any advantages/disadvantages in steering or compensation when competing at low latitudes or in the opposite hemisphere, and vice versa.  It seems like the effect over 2k would be big enough to be able to measure some of these things.

Likely not relevant for CrossFit due to the short distances involved and the rounding of times to the nearest second, but maybe I can blame the Coriolis effect the next time the wallball wobbles and hits me in the face?

CrossFit Games 17.4 Rowing Advice

Some unsolicited advice on CrossFit Games Open Workout 17.4 from someone with one foot in the rowing community and one foot in the CrossFit community:

The workout (unscaled) is:

  • 55 deadlifts
  • 55 wallballs
  • 55 calorie row
  • 55 handstand pushups

I don’t have handstand pushups, so my strategy was to max out on the row for an Rx score.

A lot of people have asked about rowing strategy.  Here’s what I’ve been telling them:

  1.  The row is equivalent to about 850 meters, but because you will be doing it with smoked back, smoked lats, and smoked legs, you will not be able to treat it as a straight sprint.  It will take you about as long as a standard 1K row.
  2. In terms of pacing, try to remember the number of calories you did on the last 1 min round of Fight Gone Bad when you were tired – that is about the pace you will be able to maintain.  For me, that was in the low 20s, and I finished the 55 cal row this morning in just under 3:00, so that computes.
  3. For me, I set a light damper (drag factor 105, about 3.5 on the machine I was using) and kept a relatively high stroke rate (32-33 to start, down to ~30 during the middle, and back up at the end).  I believe it’s better to keep the wheel spinning for a piece this long, because with tired lats it’s easy to fall into the trap of squishy finishes, which will sap your ability to maintain power at a lower rate.  I think once you let the rate drop into the 26 range and are tired, you start going into a death spiral that’s hard to sprint out of.
  4. Unscientifically, I’d recommend Rx non-rower men shoot for something like 1000-1100 pace, and women 600-700 pace.  Again I was a little higher because I knew I was not doing HSPUs – you will have to pace yourself if you expect to do a bunch of HSPUs.
  5. Goal should probably be to finish the row by 10 minutes if you want to have time for HSPUs.

I see that a previous post on Calories to Pace conversion is getting some hits today – thanks.

Good Luck!

US Women’s 8 – Why Is No One Talking About Them?

This seems like a no-brainer, but they seem to be getting a lot less press than “will the Men’s 8+ qualify for Rio” etc. etc.

U.S. Women’s sweep rowing has built an unprecedented dominance in their sport – arguably the longest world/Olympic championship streak of any sport in history, men or women.

This is an astonishing achievement.  Where is the press?  Where is the awareness outside of the relatively small rowing community?

While the women’s national teams in other sports fight for equal pay and status, we have the most dominant US national team of any sport, men or women, and it’s hard to find any press coverage of them until this article came along:

http://www.usatoday.com/story/sports/olympics/2016/06/14/americas-unsung-dynasty-the-womens-8-of-rowing/85899786/

As a father of daughters, equal time, equal pay, and equal status are big deals to me.  Let’s give them the public awareness and support they deserve as they go to Rio to defend the biggest winning streak of all time.

National Learn to Row Day June 4–Try on-water rowing!

Saturday June 4 is national learn to row day – many rowing clubs are offering free open houses at which you can try on-water rowing in a safe and supervised environment.

You can look up a club near you that is hosting an event here: Click to see

In North Jersey, I’d recommend the following:

Bergen County Rowing Academy (Overpeck Park North End)

ACRA (Monksville Reservoir)

Maroon Blades (Ridgewood)

Passaic River Rowing Association (North Arlington)

Nereid Boat Club (Rutherford)

Rockland Rowing (Hudson Valley)

CrossFitters – this is your chance to try a new sport that you are used to simulating in the gym.  Weather forecast is awesome – try it out!

IMG_4047IMG_4657