Two earlier studies showed ranges of high:low intensity movement in the range of 1:3-1:4 or 1:6. So these authors studied sparring matches at the 2007 World Championships and 2008 Beijing Olympic Games. They found that “athletes in these competitions spend more time studying, approaching, and preparing a new attack on their opponents than on executing attacks.” The high:low ratio was ~1:7. The numbers of offensive and defensive attempts were ~15-20 kicks and punches per round (while in boxing they cite 80 punches/round as common).
So what’s that mean to the average karate player? The findings suggest “that matches may be slightly more cadenced by better athletes, who seem to attack only when there is a fair chance of scoring.” This is consistent with the karate precept “Strike when the opportunity presents itself.” In sparring matches the openings open and close quickly, so you’re better off being prepared to strike suddenly and with a flurry, than to waste a bunch of energy with endless flailing that only tires you out but makes you feel like you’re doing something.
As far as training goes, if you want to get in shape for sparring, then spar. Keep in mind the flurry nature of the activity. Endless roundhouse kicks or punches in a steady rhythm won’t help, you need to have breaks in the pattern. Your non-technical training (i.e. general cardio & conditioning) would be well spent in some kind of interval training.
For example short bursts with the Martial Ropes interspersed with a period of active rest (walking around). Or you can do short bursts of plyometric pushups, jump squats or the exercise of choice, then have a steady state “rest” on the Ropes. Experiment and have fun. Give me a shout and I’ll send you the complete list of authors for the above reference.