Training & Nutrition - Cardio and Strength playing Leapfrog?

I noticed today on my interval sessions (ski, but you folks can think bike) that I pushed a MHR of 185. In fact, I decided after the second pass that I was gonna go just do 6x3min VO2max intervals today. Don't ask me why. Originally I had planned LT intervals but it just felt right today.

Anyway, I hit 181, 183, 185, 180, 183, five times. Kicker is this. Two weeks ago I did the same VO2max intervals on the same hill but at the top my muscles were burning. Today, nothing. In between I've been really upping my strength sessions, six altogether in two weeks.

So it seems like I have the strength to push my HR way up there. It seems like my cardio now has to catch up. My question is this: Is this the way it works? Strength gains to where your cardio is easily stressed, then cardio adapts. When cardio adapts, you find you don't have enough strength to push your cardio to the limits, then you start the cycle allover again?

Sorry for the rambling post. Training books don't address this. It's just observation about myself. Am I on the right track?

Good training session. VO2 intervals rocks. :-)

I won´t dissapoint you but you have to remember that things don´t change that fast. Strength training might help your performance in those short intervals and so can interval training itself. Maybe the reason was that you reduced your endurance training for a while(?).

There are good days and there are bad days, and today was obviously one the good days. I don´t think you can address your performance today to any strength gains.

See if this makes sense, in an overly simplifed fashion:

To gain muscle strength, you grow new tissue--new muscle fiber, new blood vessels (capillaries), bigger vessels (veins and arteries), even the bones and ligaments get bigger. To handle this new tissue, the lungs need to absorb more O2, and the heart needs to push more blood through the new tissue. So, for a while, the heart and lungs are more stressed, until they adapt to the new demands of the new tissue. That means the cardio-respiratory system does need time to "catch up" to the strength gains.

It also takes longer for the cardio system to build up and improve as well. So your muscle-strength and efficiency will improve quicker. That's why you usually don't need to do very much sprint & interval workouts on the bike, only about 10-15% of the total training time.

Furthermore, prolonged strength training will increase the amount of contractile proteins in the muscle cell. The proteins have to displace something and you get an effect called mitochondrial dilution.

From the MAPP
http://home.hia.no/~stephens/

Mitochondrial Dilution
When a bodybuilder trains, the goal is to make each muscle fiber as big as possible. Muscle fibers have contractile protein, mitochondrial protein, and other components. Increasing the relative proportion of one component (like more contractile protein) means that you have relatively less of everything else in the same fiber (like mitochondria). From an endurance standpoint this is not a good adaptation. We even give it a name in sports physiology circles, mitochondrial dilution. The bodybuilder's muscles may actually become more easily fatigued as they get bigger, because their mitochondrial density is not increasing at the same rate. The bodybuilder accepts that because the name of the game is size, not endurance.
It is possible for the endurance athlete to gain some muscle size and maintain mitochondrial density, but it requires that the volume of endurance training be maintained. If you are a runner and you decide to get stronger in the weight room by really doing a lot of strength training 3 days a week for an hour, you will probably drop some of your running volume to fit it in. After 6 months you have gained 5-10 pounds of muscle, you look really good, and you are running 2 minutes slower for 10k! Why? Well besides having to carry around 5-10 more pounds of muscle that you can't use when you are running, you have probably lost endurance capacity in those bigger stronger quads. So, you have a lower lactate threshold due to the detraining of your leg muscles, plus you are less efficient due to the increased bodyweight (and decreased training volume). Oh well, at least you LOOK Fast.

You ever watch World's Strongest Man competitions? I always wondered how the fat guys do so well. Sometimes you'll get the odd bodybuilder who looks strong but can hardly lift more than me and you!

Heh, heh... That's like comparing a real bike-racer vs. an OCP... :) The fastest guys around here always have old well-used beat-up, but immaculately tuned bikes. They wear worn-out faded 7-11 jerseys. The OCP guys? Yah, they look nice in their brand-new bikes & kits, but can they actually ride fast??? What about the risks of getting bugs splattered on your pristine bike & shades? ;)

It also takes longer for the cardio system to build up and improve as well. So your muscle-strength and efficiency will improve quicker. That's why you usually don't need to do very much sprint & interval workouts on the bike, only about 10-15% of the total training time.
Good point. When somebody who has never weight-trained first starts, there are noticeable results after a couple sessions. When first starting cardio training, you don't notice changes for a couple weeks or more.