In an effort to deduce what represents a "good" value for the sprint distance index (SDI) I have carried out some analysis.
According to: "Swim to Win: Train Like a Champion," By Ed Nessel;
The racing formula for a 100 backstroke is:
Let x = (best 50 time)
1st 50 = x + 1
2nd 50 = 1st 50 + 1.5
Similarly, the racing formula for a 200 backstroke is:
Let y = (best 100 time)
1st 100 = y + 3 ...to... y + 4
2nd 100 = 1st 100 + 3.6
It follows that if x is your best 50 time in seconds, your best 100 time should be about 2x+3.5.
It follows that if y is your best 100 time in seconds, your best 200 time should be about 2y+11.
The "ideal" SDI for 50/100 backstroke is then:
SDI(50/100) = (log(x/50))/(log((2*x+3.5)/100))
A graph of this function is shown in the attached file.
The first thing we learn is that the "ideal" SDI depends on how fast you swim. For me, my best 50 back is 31.01 seconds, so my ideal SDI(50/100) = 1.13. My actual SDI(50/100) = 1.14. I'll take that. If you are faster, your ideal SDI is lower. If you are slower, your ideal SDI is higher.
The "ideal" SDI for 100/200 backstroke is:
SDI(100/200) = (log(y/100))/(log((2*y+11)/200))
A graph of this function is shown in the attached file.
Again we see that the "ideal" SDI depends on how fast you swim. For me, my best 100 back is 65.89 seconds, so my ideal SDI(100/200) = 1.24. My actual SDI(50/100) = 1.22. Again, I'll take that.
One could discuss whether Nessel has the best possible racing formulas. Others have advocated slightly different splitting for the 100 and 200. Using the approach taken above, one could generate a SDI curve for another racing formula. The best splitting is also stroke dependent. Again, the above analysis could be applied to other racing formulae for other strokes.
In an effort to deduce what represents a "good" value for the sprint distance index (SDI) I have carried out some analysis.
According to: "Swim to Win: Train Like a Champion," By Ed Nessel;
The racing formula for a 100 backstroke is:
Let x = (best 50 time)
1st 50 = x + 1
2nd 50 = 1st 50 + 1.5
Similarly, the racing formula for a 200 backstroke is:
Let y = (best 100 time)
1st 100 = y + 3 ...to... y + 4
2nd 100 = 1st 100 + 3.6
It follows that if x is your best 50 time in seconds, your best 100 time should be about 2x+3.5.
It follows that if y is your best 100 time in seconds, your best 200 time should be about 2y+11.
The "ideal" SDI for 50/100 backstroke is then:
SDI(50/100) = (log(x/50))/(log((2*x+3.5)/100))
A graph of this function is shown in the attached file.
The first thing we learn is that the "ideal" SDI depends on how fast you swim. For me, my best 50 back is 31.01 seconds, so my ideal SDI(50/100) = 1.13. My actual SDI(50/100) = 1.14. I'll take that. If you are faster, your ideal SDI is lower. If you are slower, your ideal SDI is higher.
The "ideal" SDI for 100/200 backstroke is:
SDI(100/200) = (log(y/100))/(log((2*y+11)/200))
A graph of this function is shown in the attached file.
Again we see that the "ideal" SDI depends on how fast you swim. For me, my best 100 back is 65.89 seconds, so my ideal SDI(100/200) = 1.24. My actual SDI(50/100) = 1.22. Again, I'll take that.
One could discuss whether Nessel has the best possible racing formulas. Others have advocated slightly different splitting for the 100 and 200. Using the approach taken above, one could generate a SDI curve for another racing formula. The best splitting is also stroke dependent. Again, the above analysis could be applied to other racing formulae for other strokes.
