**Note: The techniques described below are designed for competitive athletes with a high degree of fitness, they are NOT appropriate for deconditioned persons.**
In my opinion far too many athletes in sports that do not require great linear endurance spend FAR too much time training linear endurance qualities.
For example, traditionally boxers perform sessions of "road work" in which they jog long distances at a moderate speed, often combining this jogging with shadow boxing or throwing combinations of punches. This work often lasts for up to an hour at a low intensity level. Why do this when the nature of the competitive sport is 3 minutes rounds at high intensity? This long duration / low intensity work can be worthwhile in the off season as a means of general physical preparation but it has no place when training becomes more specific in the pre-competition period. A far more appropriate training methodology is to work on lactate threshold in 3 minute time periods, attempting to far exceed the competitive demands of the sport so that when the time comes to step in to the ring the focus can be on technical perfection instead of just "getting through it". Frankly I find it distressing to see so many boxers "tire" after 3 or 4 rounds, even at international level there is no excuse.
Have a look at your own sport and the intensity level / durations involved. For example soccer typically involves near maximal bursts lasting up to 1 minute followed by longer periods of less intense work. This gives you an idea of how best to structure your training outside of the weights room. Below I have listed a series of whole body exercises that you can use to increase your lactate tolerance and work output. If these are to be effective you MUST work at the highest possible speed at all times. Set your work and rest levels to match or just exceed those of your sport, for example boxers would work for 3 minutes then rest for 1 minute, repeating up to 12 times.
This work level is extremely uncomfortable, many trainees will feel nauseas during lactate threshold training, some are actually physically sick. I make no apologies for this! By raising work capacity far beyond that actually required by your sport you will be able to operate at a speed far beyond that of your fellow athletes. When others tire and lose effectiveness late in the game you have the chance to still be at your best. This level of lactate tolerance and work capacity is often what separates winners form also rans, so get your puking and discomfort out of the way in training and then go on to excel in the competitive environment.
Bounding off alternate legs
Bounding off both feet (kangaroos).
Sprints, fast pace tyre dragging.
Pike jumps (jump high, bring the knees to the chest, straighten legs, land, repeat).
Medicine ball throws (various directions and stances).
Standing shuffle splits (split feet forward / back, bring feet back together, repeat).
Shape Drills (imagine a letter drawn on the ground, e.g. an "H" shape. Move the feet to "draw" the shape on the ground as fast as possible).
Skipping rope work, various types.
Light dumbbell or weightless swings or snatches.
There are many other possibilities for exercises but this list should provide you with enough variety and ideas to get started with lactate threshold work. Now get out there and start making it happen!