A Proposal for Alternate Definition of 'Threshold' for TIers
i just got my Aquapulse and have been playing with HR as it relates to swimming. In other threads, forum visitors have asked about lactate thresholds in HR training as it relates to swimming. However, in my small experiments with swimming, I have found another threshold which is more valuable.
the threshold that i might normally set as a training marker in running or cycling can be based on and definitely related to HR. i moved quickly from HR threshold to effort levels of Perceived Exertion. I could use these more readily in running and cycling, especially in interval training.
however, when i started TI, i began noticing that i rarely hit any kind of max HR where i could only sustain that level of effort for a short time or distance. i found it more valuable to use another metric for threshold setting and that was the threshold at which my form broke down. i find that i reach this threshold far before my HR reaches any kind of unsustainable effort level.
so as a proposal for an alternate threshold to be used for TI swimming, I wanted to say that perhaps using efficiency threshold as a training marker would be a good idea.
to set your training efficiency threshold, you would, through experimentation, use the TT to keep increasing the tempo until your form reaches its upper limit of sustainability, ie. only can keep it for 25y and it starts to noticeably break down after that distance. then you have a threshold tempo to work in and around with your focal points, slowly increasing distance and playing with the tempo to readjust your nervous system around.
from a data standpoint, i believe that you should be able to determine this by graphing your time and SPL over a set distance against tempo and the moment your time stops decreasing, and/or your SPL jumps, that is your tempo threshold.
unlike HR thresholds which tend to be very static and can move maybe a little bit through increases in fitness, efficiency thresholds can move a lot as your skills increase.
i have found now that i have plateaued in my efficiency threshold where my gains are now a lot harder and a lot smaller. at around 1.04 tempo is where i start to lose my form and my speed is hard to maintain over longer distances. it is a maddening but challenging place to be, where i find that increasing the tempo from there can actually make me slower or not change speed at all! but it was much easier moving my efficiency threshold from slower tempos and then as i approached 1.04, it got a lot harder.