Kris Freeman

This summer I have spent a lot of time and effort dialing in the right insulin dose for 30k and 50k events with good success. I also revamped my strategy for 15k length races but have not had the opportunity to test it much. It was necessary to change this strategy because my glucose levels were dropping perilously low directly following my races. These low blood sugar episodes annihilated my immune system last season.

Briefly, the new strategy is to frontload my insulin dose before the race instead of during it. I take a 30 minute extended bolus 30 minutes prior to the start of the competition. An “extended bolus” means that the dose of insulin my pump gives me is spread out over a half hour instead of given all at once. In the past I would give myself this dose directly before the start of the race.

The strategy was changed because the synthetic insulin I use does not reach its full effectiveness or “peak” until 45 minutes after injection.

This is a simple timing change but still requires testing and trial and error to do properly. The first time I employed the new method was at New Zealand Nationals in a 15k classic with the Canadian National Team. I took three units 40 minutes prior to the start of the race. I finished with a blood sugar of 240. (Normal blood-sugar range is 70-120, high blood sugar increases lactate production)
I made a note that my sugar was high with this dose and that I should increase it to four units for my next max effort. I also decided to move the dose timing up by 5 minutes.

My next race effort in the 15k range. was the Whiteface Hill climb roller-ski race. I took 4 units 35 minutes prior to the start. I had a good race but my blood sugar control was terrible and very disconcerting. I was at 350 and had a lactate of 12 to go along with it. Clearly I had way under-dosed again.

Whiteface was supposed to be my last 15k max effort before going to Finland but I decided I needed to test the new dosing strategy one more time. Mt Moosilaukee is only 25 minutes from my house and Ruff Patterson was nice enough to add me to the start list when his team did their annual timetrial on Sunday. This time I upped the dose to 6 units and took it 30 minutes prior to start.

It was cold out and misting. The rocks on the bottom half of the course were slick. About half way up I hit the snowline and the footing actually improved. The trail was a nice firm snowy bootpack. My heartrate was bouncing between 175 and my max 181 the entire way. I finished up in the clouds to find that I had run a new course record 35:16. The previous record was 35:23 set in 1998 by Marc Gilbertson. That wasn’t the best news of the day though. My bloodsugar was 105 at the top. I have found the sweetspot so to say and just in time.

 

Since the Olympics I have been formulating a plan to prepare my insulin dosing stategy for 30k and 50k races.  I decided that the best way to do this was to do four to five time-trials over the course of the off-season.  The first timetrial was two days ago in Bend Oregon.  I set my basal insulin at my current resting rate which is .5 units per hour.  For reference the basal rate I used at the Olympics was 2 units per hour, or four times the dose I just tested.  I planned to ski 30k with the first 20k at just above threshold with maximal effort over the last 10k.  The effort I put in was reflected by my lactates.  My heart-rates were very low due to suppression from heavy training.  My hypothesis was that my blood glucose would remain constant for the first 20k and then rise over the last 10k due to the anaerobic nature of a maximal effort.  To my surprise my glucose remained constant throughout the effort.  I fed an average of 10 ounces of Gatorade per 5ks.   Throughout the test I also compared the data that my new continuous glucose monitor  (cgm) gave me to the results I got from my blood testing Lifescan glucose monitor.   The numbers were close enough that I am now confident in the use of the cgm during races.  All of the data from the test can be found below.

I skied thee 7k loops followed by four 3k loops.  I stopped at the end of each loop for blood testing.

May 31, 2010 Bend, Oregon
44 F, Light rain
30km Pursuit TT
Kris Freeman

KM,       Time In,      Time out,    Split,      HR,    CGM,     BG,       Lactate,      Feed

Start                                                              106,     100
7km,        18.11            19.41,        18.11,    146,      88,        105,         5.6,          10 oz
14km,      37.11            39.12,        17.30,   155,      84,        119,          6.7,          11 oz
21km,      57.01           58.31,        17.39,    152,      96,        107,         5.8,          5 oz
24km,      1.06.30       1.08.06,     7.59,     155,      89,        108,         9.0,          7 oz
27km,      1.15.23        1.16.50,      7.17,     156,      96,        112,         8.9,          12 oz
30km,      1.24.26       1.25.56,      7.36,    157,       100       100,        9.1,          12 oz
33km,      1.33.17                            7.21,    160,      105        125,        10.3

Switched to skate at 14km

As a  diabetic, balancing my blood sugar during races is critical for a good performance.  This is a difficult task given the numerous factors that can affect glucose in the blood stream.  For this post I am only going to focus on one such factor. .. terrain.

Through extensive testing I have learned that when I am in an anaerobic state my glucose rises significantly.  When I am in an aerobic state my glucose drops.  The rate that it drops increases with the intenisty of the effort.  I am at peak sugar burning mode at threshold.  Once my heartrate climbs into level 4 and level 5 territory my glucose suddenly begins to rise.

In a normal ski race I am constantly bouncing between a threshold effort and maximal effort.  My heartrate peaks at the top of a hill and slows as I go down the other side.  Thus my glucose levels rise and fall throughout the race until I put in a final anaerobic surge over the last few kilometers of a race.   A normal glucose level for a non-diabetic ranges from 70-140 during a race.  At below 70 a racer would be experiencing a “bonk.”  So it is important that I do not use too much insulin during a race.  However it is just as important that I do not use too little insulin.  My lactate level starts to rise unnaturally when my sugar reaches a level of 240 or more.  The margin for error is small, but thanks to testing on the Center of Excellence treadmill and many races and timetrials I have developed an inuslin dosing strategy that generally gives me a glucose level of 160 at the finish of a 15k race.

There are two types of insulin dosing, basal and bolus.   Insulin is delivered in measurements called units.  A basal insulin is a constant drip that is delivered into my bloodstream 24 hours a day by a mechanical box called an insulin pump.  The pump I use is called an OmniPod.  The bolus insulin is also delivered by the pump and is given at meal times or at any time a significant amount of carb is consumed.  I progam the pump and override the program when need be.  It is not an automated devise.

My basal rate depends on many different factors that I am not going to go into in this article, but for reference lets assume  that I am using my most commom basal dose of .7 units per hour in the days leading up to a ski race.  My pre-race dosing strategybegins 1.5 hours before the start.  At this point I double my normal basal insulin dose to 1.5 units per hour.  Twenty minutes before the start I bring the basal rate up to 5 units per hour.  I keep the basal rate at 5 units per hour until the completion of the race.

Yesterday’s Race to the Castle on Whiteface and other hill-climb timetrials present a different challenge for me.  Because there is no significant terrain variation there is no place to recover.  I am in an anaerobic state for over 50% of the race.  Thus my bloodsugar constantly rises unless I take even more insulin than in a conventional race.  During yesterday’s race my non-racing basal rate was .5 units per hour.  During the race I increased my basal rate to 7 units per hour and I still finished the race witha a relatively high glucose level of 204.  I have not documented any ill affects from racing at this glucose level but there is definately room for improvement in my controlm durin hill climbs.

I had compartment release surgery on both legs yesterday. I am on a lot of pain medication. There was little doubt that the surgery was absolutely necessary once the operation started. My surgeon described the fascia covering my anterior compartment as scarred and as thick as an orange peel. The operation took longer than planned because I also had scar tissue binding down a nerve. Scraping the tissue away from the nerve was delicate work. Using three incisions per leg, all five of my compartments were released on each leg. The doctors were surprised by how much repair was needed but they were very happy with the results. I can’t wait to get out skating on healthy legs.