A comfortable erect posture with the head level encourages the correct body alignment for jogging. You should survey the path in front of you for obstacles and irregular terrain, but your neck should not be bent forward. Do not look directly in front of your feet, because this detracts from jogging efficiency and leads to muscle strain in the neck and lower back if you maintain this posture for some time.
The hands, which are loosely closed, should be carried slightly lower than the elbows for energy conservation and comfort. This posture tends to relax the neck and shoulders. The low hand position works against generation of powerful pumping action from the arms, but this is not necessary for jogging. Sprinters require power from the arm swing; joggers swing the arms for rhythm and balance. The arms should swing backward and forward and should not cross in front of the body.
The jogging stride should be short and compact, with the foot landing beneath the knee. This aids in keeping the body erect and prevents overstriding. The jogger should land softly on the heel and rock up through the ball of the foot to the toes for the push-off. The body weight transfers from the heel along the outside edge of the foot to the toes. This distributes the impact over a greater surface area and for a longer time, resulting in smooth, energy-efficient locomotion. The landing should be essentially noiseless.
The main difference between walking and jogging is that the body is airborne during each stride while jogging. The airborne or “float” phase accounts for about 30 percent of the length of stride. The airborne phase represents one of the primary reasons the energy cost of jogging is higher than walking: More energy is required to propel the body into the air with each stride. Overstriding is to be avoided. When the ankle is forward of the knee upon landing, the foot acts as a brake to forward motion. This reduces the efficiency of jogging and also puts stress upon the knee joint, increasing the probability of injury. Mobility can be an issue when you have a knee injury.
Mechanical factors that make jogging such a good aerobic conditioner are the very ones that can produce injury. The fact that joggers are airborne with every step results in a high-impact landing. The ground reaction force when the foot strikes the surface, coupled with the subsequent push-off that propels the body upward, is approximately equal to three times the body weight. Because the average jogger steps between 1,500 and 1,700 strides per mile, the knees, hips, and feet absorb the shock of landing that many times. Multiply these values by the number of miles covered in a week, and you can understand the cumulative forces operating on the jogger.
But joggers make a number of bio-mechanical adjustments that help to dissipate the shock. For example, the flexed position of the knee and ankle when the heel strikes the ground allows the contracting muscles to stabilize the involved joints. In the contracted position the muscles act as shock absorbers that diffuse the impact of landing. By the time the shock reaches the hip joint, it has been effectively reduced to one-sixth of its original intensity. These adjustments allow joggers to run for many years without serious injuries or premature wear of the joints.
Despite this remarkable adaptability, most joggers sustain an injury or two at some time during their many years of jogging. Fortunately, most of these injuries are minor and respond well to rest or treatment.
