A hockey player can do bench presses, and squats, or run stairs till the cows come home without necessarily becoming a faster skater. The reason may lie in the fact that the player does not fully utilize those muscle groups most important to the skating motion. A muscle group which has a major function in one activity may play a minor roll or none at all in another. For example, the abductor (the outer thigh) is very important for skating, because it does the leg extension, However, during running, it becomes one of the stabilizing muscles. Hockey skating is not a front to back motion, but on involving the application of oblique forces.

The abductor, along with the adductor (the inner thigh) are largely ignored in most dry-land training. These muscle groups in conjunction with the gluteus maximus, upon which each of us sit, if properly balanced with all others provide a powerful skating stroke. In other words, if one of the muscle groups is much weaker than another, it will tend to tire sooner, resulting in an inefficient stride due to the stronger muscle group dominating the motion. When the inner and outer thigh muscles are relatively weaker, their early fatigue changes the oblique stroke to a motion more closely akin to running than skating.
There are methods available to develop these muscles. Probably the most familiar is the slide-board which directly isolates the two muscle groups. Once a certain amount of strengthening of these groups has occurred, however, the athlete must advance to exercises more closely correlated to a balanced stride. The most simple of these would probably be an oblique bounding motion. As strengthening increases, motion-specific resistance training can be applied to both dry-land and on-ice training.

With some of my pro's and elite youths, on-ice I add a leg harness designed for notion-specific overloading of the pertinent muscle groups, with up to 10 athletes using a separate harness at the same time. Unlike other on-ice resistance methods, it will not distort your balance or your skating motion. It overloads all of your leg muscles, strengthening them in a motion-specific manner including quads, buttocks, hamstrings, calves, inner and outer thighs, as well as lower back.
Because it can be worn during all of the skating and hockey drills, it has a cumulative effect of improving muscular endurance and aerobic capacity, while at the same time increasing the cardiovascular output. Since it applies constant resistance throughout the drills, they make the wearer work harder, delivering greater benefits in the same amount of time, or similar benefits in less time.
Proper technique, however, although moving the skater over a greater total distance, because of the moving of the centre of gravity on oblique angles, results in transporting him down the ice at a higher relative speed, because greater net forces can be applied through a full range of motion. And is not speed our goal?

Put simply, you cannot ultimately obtain the "explosive" speed at full forward stride using the straight line skating technique, because maximum force cannot be applied when the ice is moving away from the force being applied. We have only to look at speed skaters and how they apply this angular force. Don't let someone simply discount this by saying "speed skating is different". Yes, the sport is different, but from speed skating we can learn how to apply a broader understanding of physics to produce such efficient force, which can be applied to hockey skating.