I appreciate your response, but I'm not sure I understand what you are saying. Per what I was listening to yesterday, the flash normally goes off for 1/50000 of a second. And so what the flash does is it strobes at multiple intervals throughout the shutter so the top of the sensor receives a consistent amount of light as the rest of the shot. So it strobes 20 times over 1/1000 of a second which is pretty cool.
As for being weaker... I'm not sure, but it seemed equally as blinding as the normal flash.
And I don't think HSS is for difficult lighting... I think 2nd curtain is more applicable for long exposure with flash at the end of the shot. Though I'm willing to listen if you can further elaborate.
The HSS is no the right answer to your problem! HSS is using the flash as a lamp, glowing 1/200s to keep the light on as long as the shutter is running. (Shutter sync speed). To prevent the flash to be demaged, the Hss flash is 4 times weaker than the normal one. HSS is only made to fill shadows while shooting portrait outside in the sun with wide open aperture and high shutter speed.
The normal flash is just 1/800s so the flash is delivering you the freeze and the higher power you need in a gym.
To keep the white balance under control, I would use a lee filter in front of the flash. These filters are realy cheap. You can buy a sample package from Lee with 100 different colors for 15$.
How to make it work:
1.Take your camera and make some shots in the gym with automatic WB.
2. Look with the info page on the WB.
3. Chose a filter for the flash with the same K and stick them in front of the flash.
4. Fix the WB manually to the same value.
5. Use Av mode and correct -2EV and flash correction to 0EV: the flash is than 75% and the room light is 25% of total that gives you a good freeze and non overflashed look. If you struggle with to short shutter speed, switch tomanual mode and 1/250s the E-TTL will put the right flash in.
Only one color of light - easy to adjust in the post
Enough flash power
If the flash is not using ful power, shorter repeat time
Same strategy also works for parties with a 3200k filter in front of a flash and normal lights. You can handhold and freeze with 300mm easily.
Would be nice to get a feedback if this works for you.