One of the questions that always comes up in the monthly Kettlebell Fundamentals workshops is "How many reps should I do?" The answer to that question is "It depends." Sr RKC Doug Nepodal likes to say "5 or less or 20 or more" - but what does that really mean? It means if you are doing a grind, the general rule is do 5 reps or less and if you are doing a ballistic, the general rule is 20 reps or more.
In kettlebell training, grinds are the slower exercises - you know, the ones you "grind through." Presses, deadlifts, and even get-ups all fall into the grind category. These are exercises you would do for lower reps at an appropriate weight. I tell my students if they get 5 or more grinds in a 30 second interval then they can more than likely move up in weight. I would rather see one repetition where someone had to connect and use their body as unit instead of 10 where he was repping out lighter weights using just one muscle group. And you can even get your one up with a heavy weight then drop down to a lighter bell, but if you can do ONE with good form then do it at least once a week.
I like to say that presses are one of my favorite ab exercises because to get a heavy press above my head, I have to squeeze my abs very tightly. As Pavel says, "Muscles are social creatures. They work harder when they work together." The more muscles you use, the more weight you can move. Simple as that.
Once you understand the concept of full body connection and using your whole body as a unit, you can go back and play with lighter weights using the same connectivity and do a program such as Dan John's Easy Strength, but you must first grasp the concept of not isolating muscle groups and using your whole body to lift.
The grip in the grinds is a closed hand grip squeezing the handle. When you close your grip and squeeze the handle tightly, you maintain greater tension and can move more weight because again, you are using more muscles.
Ballistics are the quick lifts - the ones where you have to maintain a balance of tension and relaxation. The swing and snatch are the two most common kettlebell ballistics. In these exercises, you want to do as many as you can until just before your form goes. Because ballistics are explosive and dance back and forth across the line between tension and relaxation you can do more reps. There is that split second at the top of the swing where you can "rest" before the next hike and snap and that moment of "relaxation" is important to keep you going. Swings that are all tension all the time are very ugly and make your neck ache afterward. At the top of the swing and snatch, stand up tall, don't chicken neck and make sure your face is relaxed. As MRKC Jeff O'Connor says, "Ugly faces don't make you stronger!"
There is a place for heavy ballistics and a place for light ballistics. Make sure to make time for both. For example, a whole bunch of light snatches such as in Kenneth Jay's Viking Warrior Conditioning protocol will shred you and make you lean, but unless you are going heavy at least once a week you probably will sacrifice some strength in that lift.
The grip in the ballistics is looser than in the grinds - you can even have an open grip at the top of the snatch! When you crush grip the handle in the quick lifts, the handle rubs your hands as it turns and causes callouses. The arms are more of a guide in the ballistics than a driving force so you don't have to squeeze the bell tightly.
**Note: for more information on the balance of tension in the kettlebell swing, check out an article I wrote for Dragon Door called How Hard is Hardstlye in the Kettlebell Swing.
So, how many reps should you do? 5 or less heavy reps for the grinds and a whole bunch of ballistics as long as form is not compromised. Once you understand how the body works as a unit, play around with different bell sizes on different days - just know that you have the potential to lift a great amount of weight when you are connected and not isolating muscle groups.