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Sunday, September 9, 2018

Post flat tire metrics, a look at concurrent training?

One man's trash is another man's treasure......

A few days ago I was just getting ready for a "monitored" interval after doing a 1 hour warmup on the road.  To preface, I only ride hard a couple of days a week and on those days wear all 3 BSX sensors with light shields and my Hexoskin shirt.  There is a bit of effort involved getting it all together and having it all working.  After the 20 minute "gear-up" (like the astronauts), it takes about an hour to reach the location of testing.  On this particular day all was well until I hit the lap button beginning the interval and promptly got a flat tire.  Even worse, I have tubeless tires that can be finicky with re inflation after a change.  The bad luck continued with going through 2 air canisters and having a leak around the valve.  Before calling my wife for help, I tried using a hand pump that shouldn't have worked (does not provide that blast of air volume for tubeless inflation).  However my luck changed at that moment and after pumping like a maniac for several minutes, the tire bead seated.  I proceeded to finish pumping, got back on the bike, turned around, warmed back up 10 minutes and hit the hill again.  The power profile wasn't bad, but towards the end of the effort, I felt something was not quite right.  This post will be about my experience and a brief look at some literature as well.  

The use of both resistance and aerobic exercise in the same session is called concurrent training.  There are an infinite amount of permutations in regards to exercise order, intensity, and between session rest.  There is also a huge amount of literature looking at this but for my purposes, just a narrow scenario will be explored.

This is what the session looked like:
There is an almost 1 hour warm up, the flat tire change (part of that being vigorous hand pumping associated with heart rate elevation), a brief warm up then a 5 minute Fast start interval.
A closer look at the 5 min FS:
Several remarks:
  • The starting HR, costal O2, RF O2 sats were all within the usual range
  • The prompt HR elevation at 30s was similar to other FS intervals
  • The Costal O2 pattern (initial drop during the FS, stabilization at about 280 watts, further drop in green with higher power of 330 watts, re-stabilization after power cut) was very typical
  • The RF O2 pattern was also very similar to previous FS intervals (see previous FS posts)
  • But, I knew something was off.  I was severely winded and fatigued after.  My plan was to go for a longer interval but couldn't do it.  At the time, I couldn't figure out why since my Costal O2 was not excessively low, nor was the HR that high.

After looking at my Hexoskin data (post ride), it becomes more understandable:

Compared to previous FS intervals of similar power:
  • The baseline ventilation is about double.
  • The mid and latter portions are at near maximal.
  • The 1 min post effort ventilation (while coasting) is almost double.

What about later in the ride, is the ventilation elevation still an issue?

Here is the 1 minute maximal effort:
  • The baseline ventilation was lower at 42, near usual
  • Baseline HR at usual.
  • Max HR same as usual
  • Max ventilation same as usual.
  • Interval average power slightly lower (but close).

The probable cause:
3 minutes of fast hand pumping (after the regular battle of changing a tubeless tire).
If we go back to the graphic of the whole ride above, there is a segment of the tire change associated with heart rate elevation.  After 2 failed attempts at tire inflation, I got out the small hand pump and gave it a go.  Needless to say, my expectations were low, but surprisingly it did work.  I was a bit winded doing this, but did not really pay attention to it.
Closer inspection though does confirm a significant effort in regards to HR and ventilation.
  • The fast hand pumping elevated both ventilation as well as HR (140 max).  The HR is not an artifact of motion since it was measured with the Hexoskin (I looked at the raw data and it is correct).
Comparison with a "control":
On a ride last month, I also had a flat but did not hand pump.  The flat was about 30 minutes pre interval, with no change in ventilation rate patterns.

  • It seems that a session of upper body exercise in close proximity to a subsequent cycling interval, will cause elevation of minute ventilation.
  • The elevation of ventilation is in both baseline values as well as reaching maximal levels earlier than expected.
  • The HR pre interval does not appear to elevated.
  • The O2 desaturation pattern of the active muscle does not appear to change.
  • The O2 desaturation pattern of the costal muscle does not appear to change.
  • Latter on in the session, the ventilation parameters come back to baseline.

What does the literature tell us?
Kang and associates published a study looking at physiologic parameters after a combination resistance then cycling session:

The exercise protocol was as follows (4 of the 6 strength exercises were upper body):
Essentially, either a low or higher intensity resistance session was done, then a 5 min rest followed by 20 minutes of cycling at 50% of the VO2 max power.  Measurements were done throughout with averages below:
  • There was a HR elevation in both resistance groups compared to the control (no resistance session before cycling).
  • In both men and women, Ventilation was significantly higher after the resistance sessions while cycling.
  • The low vs high resistance sessions had similar elevation of ventilation.  The higher resistance did not elevate ventilation more than the low.
  • Although VO2 was not statistically different for men, it was elevated in women and appeared to be elevated (p>.05) in men as well. 
  • There may be many reasons for this "compensation" such as EPOC (excess post exercise O2 consumption).

Although this is not exactly a simulation of my ride experience, the underlying theme is the same.  A given amount of resistance work (mainly upper body) in close time proximity before cycling can increase ventilation rates as well as total VO2.

Some take away points:
  • The addition of non cycling exercise before an interval or during a race may have significant effects on performance.
  • The usual monitoring modalities including heart rate and even muscle O2 may not be able to indicate this situation.
  • The surrogate marker of cardiac output redistribution, namely costal O2 does not appear to be predictive as well.
  • Ventilation volume does appear to be the best measure of post resistance physiologic compensation.
  • If you do have a difficult tire change, consider a longer active recovery time with easy cycling to avoid the above.  Conversely, if recovery is not an option, be prepared for higher ventilation rates and potentially higher RPE.  The time of recovery undoubtedly will vary between individuals and their circumstances.
  • Real time knowledge of the ventilation volume would have been helpful.  I probably would have delayed the interval to latter into the ride and/or limited the power/time of the session.
  • Cycling after a resistance exercise session (as in a fitness center) will have ramifications as noted.

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