My first race

So, my daughter is a cross country runner in grade 11.  She also runs a 46 minute ten kilometer race ( 6 miles).  We don't like for her to run alone in the woods even though life is pretty safe where we live, so she has motivated me to start running.  

Three weeks ago I started to run.  I got to a point where I just had to stop and walk for a bit.  I asked her how long had I run.  She answered 12 minutes!  Well that was the longest I had ever run in my life.  Before that I could always make the train or the bus in the 100m sprints but 12 minutes, wow!

Two weeks ago, I felt so good after 5 km that I went on for another 2 km.  I was up to 40 minutes of running for 7 km.

Today, I ran a 10 km city run in 53 minutes and 28 seconds.  Okay it is not Olympic time but I am quite proud as I placed 7th in my age group. 

Now of course there is a biological lesson here.  In Option B Training & the pulmonary system, students need to explain why, during exercise, the tidal volume and ventilation rate increase. As I was running, there was a significant demand of energy by my muscles which requires oxygen for aerobic respiration.  This process of respiration releases carbon dioxide into the blood which lowers the pH of the blood.  The chemoreceptors in the carotid arteries leading to the brain detect the change of pH and send a nerve impule to the ventilation centre in the brain.  The ventilation centre now stimulates the external intercostal muscles and the diaphragm to contract more frequently and to a greater extent. This increases the rate of ventilation which removes carbon dioxide from the lungs and hence the blood while at the same time brings more oxygen into the lungs. Too bad I did not have a datalogger with me to measure the rate!  This lesson does not end here.

In Option B Training & the cardiovascular system the heart rate and exercise are to be explained.  Again, the level of carbon dioxide or change of pH stimulates the chemoreceptors which in turn stimulate the signals from the hypothalamus to the heart causing an increase in the rate of contractions as well as the force of each contraction.  The stroke volume will increase for several reasons.  First the return of blood to the heart is increased as the muscles squeeze the veins forcing more blood towards the heart. Secondly, the heart relaxes to a greater extend so that more blood flows in and is then forced out with a greater contraction.  A larger stroke volume ensures that more blood flows in the arteries to the lungs which will oxygenate the blood that returns to the heart. The muscles will then receive more oxygen to continue their contractions.

Finally the production of ATP for such a long run needs to be continued.  Creatine phosphate provides an intial source of energy for only a few seconds.  As I was running a a good pace, I was able to breathe regularly and deeply. This breathing pattern allowed my muscles to continue with aerobic respiration for the duration of the race.  When I was sprinting for buses and trains, I went into anaerobic respiration which does not permit the continuous ATP production needed for longer runs.  This was why I could not run for more than a few hundred metres.

Now I am set to try to break the 50 minute mark in my next 10 km race!