Training volume + weight loss = getting sick more often?

Since my training year officially started the week of January 1, I've been trying more or less to improve my eating habits (i.e., eat less food in general, and less junk food in particular) and lose a bit of weight. Not lots, just the icing off the cake so to speak. According to popular research, each pound lost is a minute gained in a marathon, and of course climbing well on the bike is all about being lightweight.

After reading that Dutch pro triathlete and 2008 Kona runner-up Yvonne van Vlerken lost 4kg last year off her "athletic frame" (what a nice way to say short and stocky), improving her speed and performance, I figured losing the same would go a long way to achieving my Kona dream too. As of January 1, my own 5'2" athletic frame weighed over 57kg. The goal is to get down to 52kg for race day, August 2.

Right now, in mid-March, I'm at about 55.5kg. This is the lightest I've ever been in March and it shows -- my jeans are a bit loose now in the waist (though tight in the upper legs thanks to all those 14% hills I've been riding!) -- and I feel pretty toned. Since I don't have a body fat monitor, I have to use a combination of the scale, how I look in the mirror, and how my clothes fit, but I would say that even though I've been putting on muscle from all this running, cycling, upper body weights and core work, my body fat is still down. Apparently I'm now considered a hot roadie even, although I think there's a bias there....

In late January, we had a little holiday on Lanzarote to kick start the season with some high volume bike training, and as usual when we got back I promptly came down with a cold. No worries, within a few days of rest and reduced intensity training I was over it and back to the regular grind. Since then I've steadily ramped up my training volume to an average of 12 hours a week. I've been eating well, recovering well, sleeping mostly well (though never enough, it seems), and feeling fast, sleek and great. Strong as an ox, right?

Last week I had some shorter workouts with higher intensity, then the plan for the weekend was higher volume at lower intensity. Friday afternoon I ran 28 hilly km in 2:20, Saturday I rode 60km on flat terrain in zone 1/2, and yesterday was a 90km group ride with 750m of climbing spread over 3 major hills that I attacked reasonably hard, with the rest of the ride pretty easy. Came home, threw on my recovery tights, ate a good meal, and lazed in front of the TV for most of the evening. I even managed to make it to bed before 11pm as I was feeling a bit tired from 8 hours of training over the past 48 hours. But by 2am I was up and sneezing, coughing, completely congested... with what seems to be another cold.

My resting HR this morning was normal, so obviously I'm not too sick. Today's a scheduled easy day with just a short form run anyway, along with some core and upper body work at the gym that I may push til tomorrow. So I'm not too worried, but I am a bit frustrated and wondering what's up with my getting sick so often. This is my third cold in 5 months, and for someone who has more than once gone an entire year without a cold, that's pretty bad! Is it the weather in my adopted country? My increased training volume? My slimmed down physique? The fact that I'm now living full-time with a (wonderful and loving) night owl and poor sleeper? All of the above?

SportTracks has a great little plug-in called Training Load, which is basically a poor man's Training Peaks for those of us who don't have a power meter (yet!) It takes the time spent in various HR zones and intensities for training activities and calculates a TSS score for each, then graphs CTL, ATL and TSS over time. This is what mine looked like this morning:



blue = CTL aka fitness level
red = ATL aka fatigue level
pink = body weight
brown columns = the TSS or Training Stress Score for a given day's activities with general scales of low, medium, high and epic.

The "epic" event and accompanying spike on the farthest left is the marathon I ran on November 9, 2008. The following month I took it pretty easy as evidenced by the drop in both ATL and CTL, then got going again with serious training in the new year. The big jump in the middle-right, and corresponding drop in body weight is the Lanzarote trip. Since then my fitness has been steadily climbing, my fatigue is being managed through easy days and days off, and my weight has been dropping.

It's nice to see my hard work translated into pretty graphs showing improved fitness (being the data geek that I am), but I'm starting to wonder if 52kg is going to be too light to be both fit enough and strong enough for Ironman UK. Do I really have 3.5 more kg to lose, or is the risk of illness too great? If I keep going the way I am, I'll lose that weight just from maintaining my current diet and ramping up the volume in early summer when I start doing 5-6 hour rides. At that point, I guess I'll find out whether I get to eat -- must eat, even -- all the dessert I want again, just to stay well!