So let's assume that you're someone who is already enrolled in classes in some traditional martial art. Let's suppose you have some extra time and energy and want to get in better shape for your art (or for your life).
The first thing to recognize is that you're not an elite athlete (unless you are, in which case stop reading this and get a real coach). Elite athletes need elite coaching. Advice like the type I can give you is very general, very rough, and will, if followed, make you a very, very strong karateka... but not elite. Elite athletes need highly personalized and specialized programs, and they pay large sums of money for that kind of training. My blog is free. I'll get you into the top 5% of your age group. Getting into the top .1% requires an entirely different approach, and I'm not really the guy to get you there.
Still reading? Good.
Your best bet, assuming your instructor is decent, is to do more training in your art. If you're already taking one class a week, take another. If you're taking two, start taking three. The best way to improve in your art is to train in your art.
Of course, this will only work for some people. Maybe your classes are far away and you have time for more training but not more commuting. Maybe you can't afford (financially) more classes. Maybe your instructor doesn't offer more than a certain number of sessions per week to you. Maybe the classes are too demanding for you physically, and doing more would be too difficult for you.
In any of those cases, the next best bet is to remember that the best workout is the one you'll do. Any physical activity, for most of us, will be better than none. So if I tell you to do more push-ups, and you absolutely hate push-ups but like to take long bike rides, then by all means take long bike rides.
So if you're only willing or psychologically able to do some particular type of exercise, then do that. If you have some super aggressive conditioning plan that you can't follow, you're not going to make any progress. Trust me on this - I have vast personal experience designing super demanding exercise programs that I couldn't follow, and every time I did that I wound up taking a 6 month (or longer) break from training entirely and wound up in worse shape than I would have been if I'd just spent that time gardening.
If you have the energy, time, and psychological motivation to do a variety of things, and want to know the most efficient choices to make to get better at your art, follow these basic steps:
1. Get enough endurance (otherwise known as gpp, more or less, or wind).
Are you huffing and puffing and weak in the knees during class or during sparring? Is fatigue your biggest problem? If you're weak from lack of energy, you won't be able to really master the skills of karate. If you're surviving class pretty well, and when you spar your speed limits you more than your wind, then skip this section!
Long Slow Distance (LSD): The basic building block of endurance is two, forty five minute to one hour sessions (roughly) of having an elevated heart rate per week. By elevated I mean above 120, not necessarily so high that you're panting and feel ready to puke. If you're taking two one hour karate classes per week you're already hitting that target. If you're only taking one hour long karate class per week, take another forty five minutes to do something that keeps your heart rate up but doesn't kill you.
Like jogging? Jog (slowly). Or kayak. Or bike. Know a little karate? Spend an hour practicing your kata, or your kihon... but if you do that, pace yourself. Don't work so hard that you're gasping for air or shaking in the limbs. Practicing karate while highly fatigued will make your technique worse, not better. Wear a heart rate monitor and aim to keep your heart rate between 120 and 150 beats per minute. Or just pace yourself so you can carry on a conversation at any point during your training session. Maybe do a kata, then take many deep breaths, or stretch, or walk around, then do another one.
If you're getting 2, one hour sessions per week of this type of training, it's enough. More lower intensity training isn't going to get you much better results - if you love it, of course, that's great, go ahead and do it, but it's not the most efficient way to get 'in shape.' For example, I love kayaking, if I lived in a better place for it I'd kayak 4 hours a week - but that's not because it would make me better at karate, it's because I love kayaking. If you love jogging, jog more, but above 2 hours per week it's not the most efficient way to improve your karate.
HIIT is pretty popular (it's the foundation of Crossfit), and pretty simple. Do something that's really hard, but doesn't overload one particular part of your body, but rather that taxes your whole body and lungs. So, for example, pushups probably aren't good, because the limiting factor for most of us is our arms getting tired, not our overall cardiovascular system. You need to find something that can have you breathing really hard, sucking wind, and maybe feeling a bit nauseous, all in less than 20 seconds.
Great choices are the Airdyne (or similar exercise bike), a VersaClimber, power snatches (with a fairly light weight or a dumbell), and burpees. Exercises that utilize a lot of different muscle groups are best, so the fatigue isn't centralized. You don't want to fail because one muscle group is fried, you want to fail (or come close to it) because your entire cardiovascular system is taxed.
Pick a time - say, 15 or 20 s. Do the work for that time, then rest for the same amount of time, then repeat. Electronic timers (that beep on some countdown) are very, very handy for this.
Do 8 sets or so (so if your work set is 15s, 8 sets is 4 minutes of overall work). Then take an extra minute of rest, and do an other 8. The 'work' should be hard enough to really, really suck. You can build up to doing more sets, but don't go past 20 minutes or so of total exercise time, and don't do it more than twice a week. I don't mean 20 minutes of work, I mean 20 minutes total of work and rest. If you can knock out 20 minutes easily, do something harder - add weight, go faster, whatever, but raise the intensity, not the duration.
If you're doing HIIT twice a week, on top of twice a week LSD (which, remember, probably includes whatever martial arts training you're doing), that's enough endurance work. More than that isn't going to do much for you beyond wearing you out.
2. Get Strong.
I've written elsewhere about this, but it bears repeating. You can't be too strong. As we age, the thing that can negatively impact quality of life most is a lack of strength. Can't run a mile? Buy a car. Can't touch your toes? Bend your legs to tie your shoes. Not strong enough to get up out of a deep squat? Congratulations, you now need a wheelchair and your life has now completely transformed, and not for the better.
There are lots of variations of good strength routines. A basic one looks like this:
There are 5 basic 'movements' (one doesn't involve moving): upper body push (pushup, overhead press, that sort of thing), upper body pull (row, pullup), hip hinge (deadlift, kettlebell swing), squat (squat, air squat, split squat, barbell squat, even leg press), and core stabilization (plank, crunches, planks on a bosu ball, ab wheel rollouts).
If you don't have time for a dedicated block of strength training, pick exercises in each of these movements and fit them in wherever you can. Do pushups when you wake up. Do a few air squats during your lunch break. Hang a chin-up bar by your bathroom and do a couple of reps every time you go into it.
If you do have time for dedicated strength workouts (say, at least 20 minutes at a time, but not more than 40), here's a simple starter program.
Pick one exercise for each of those 5 basic movements that you can do in your facility (gym, your house, wherever you are working out) with the equipment you have (even if that's just your body and the earth's gravity, you can manage, although a few cheap items will make life much easier, like a chin-up bar). Make sure each exercise is hard enough that you can do at least 8 reps but no more than 15 or so (let's be fair, if you can do 6 or 20, it's not a tragedy, just adjust your set numbers accordingly).
Do 4-6 sets of each exercise. I like to do these in circuits - one push set, one pull set, one hip hinge set, etc. so I do 5 different exercises, then rest a couple of minutes, then do them again, repeating the whole cycle 5 times (give or take). You can do 4 sets of push, then 4 sets of pull, and so forth if you prefer. If you do these quickly you can get a HIIT effect - but you can't get something for nothing. If your strength training is taxing your cardio to the point that it counts as HIIT, then it isn't going to be AS good as strength training. So with limited time and energy, that might be a good compromise, but you'll get better results separating the two.
Repeat this workout twice a week. If you're a beginner, stick with the same exercises. Once you've gotten good at them, you can swap out the exercises every workout. Do pushup for your press one workout, then overhead kettlebell presses the next time instead.
Do fewer reps each set than you can. So if you can do a press 12 times, but can't get 13, then your work sets should be around 10 reps, not 12.
Try to do do some exercises with just one limb - presses with one arm, one legged squats, stuff like that. Otherwise you risk letting your dominant side get much stronger than your weaker side, and you lose the ability to stabilize asymmetrical loads.
If you want to add muscle, make sure your reps are in the higher range (10-15) or do more sets. Volume leads to hypertrophy.
Do every rep as fast as you can without hurting yourself. Some exercises are 'grinding' exercises - they are slow and take a ton of effort, while some are more explosive. If you can, rotate between those two. For example, I might do one arm pushups (which is a grinding, slow exercise for me, and which I can only do for a few reps), then the next workout do regular pushups - but do more of them, and do them really fast, perhaps with a clap or something in there. Ditto for squats - I'll do one legged squats, which I have to grind out, and alternate the next workout with squat kicks (squat down on two legs, throw a front kick as you explode up to a standing position).
Do this workout twice a week.
If you're training in karate two hours a week, adding in specific HIIT workouts a couple times a week, and strength training twice a week, that's already lot of training.
If you still have the energy (physical and psychological) and the time and the desire to do more, you can try a few different things. You can spend more time working on your basic skills - there is really no end to that. When you do your skill training, make sure MOST of your skill training is done while you are NOT fatigued. When you're tired you get sloppy, and training sloppy technique is counterproductive.
Beyond that, you can do some periodization. spend 6 weeks of really heavy strength training - maybe pick a particular movement (say, squat) and hammer it with extra sets and reps for 4-6 weeks, while still doing the rest of your work, then hammer something else. Do some sprinting.
4. Temporary measures.
I wrote in a few places above that one shouldn't do more than a certain amount of these things. There are times, though, when you might want to push the upper limits of that training. For example, before a promotion (belt test) I might do extra HIIT sessions for a few weeks to get my endurance really high so I can survive the test.
That's fine, but you have to make sure to do those things for relatively brief periods of time (3-4 weeks), and carefully monitor yourself for overtraining. If you start to feel tired all the time, or your HRV plummets (assuming you're measuring your HRV, which is a topic for another blog post), or you're getting sick a lot, back off. The older you are and the more stress your under and the worse your diet and the worse your sleep the harder it will be for you to tolerate high volumes of training.