Retro running is a lesser known term for a well-established athletic activity: running backward. Retro running has a number of significant applications throughout sport, both as a training aid and as a rehabilitative tool in the management of various leg injuries. In some sports science commentaries, the broader expression "retro locomotion" is used to describe both retro running and the gentler version, retro walking.
The value of retro running in training is rooted in the mechanics of the running motion. The development of an optimal running stride depends on the ability of the athlete to power the quadriceps (thigh) muscles forward to create extension in the knee joint. As the knee extends, the lower leg muscles respond through the contraction of the calf muscles, which in turn direct the Achilles tendon and the muscles of the foot to complete the stride. The counter movement, the flexion, or bending, of the knee, is a movement that originates with the hamstring muscles and tendon located at the back of the thigh behind the knee. To generate an efficient and powerful stride, the strength of the quadriceps relative to the hamstrings should be in approximate ratio of 3:2; when the quadriceps is too powerful, the knee will sustain forces it is not constructed to bear, a circumstance that may lead to overstress and ultimately damage to the anterior cruciate ligament (ACL), the connective tissue essential to knee stability. If the quadriceps is weak, the hamstrings tend to dominate the running muscle motion, often becoming overstretched through the repetitive movement of running. This circumstance will often result in hamstring pulls or tears. Distance runners are often susceptible to an overly strong quadriceps structure and resultant hamstring injury.
Other injury sites created by the structural imbalances that are accentuated by the natural running motion are lumbar (low back) region, hip, and groin. Shin splints, compartment muscle injuries of the lower leg, and Achilles tendon injuries are all most often connected to either structure or muscle imbalances created by running programs that provide insufficient stretching and flexibility exercises in relation to the distances covered in training.
The first benefit of retro running is that it tends to counteract the forces that produce musculoskeletal pain. The body is designed to move more efficiently forward than backward; the maximum speed of the retro runner is no more than 80% of maximum forward speed. When the retro running is performed on a treadmill or stationary exercise machine, the muscles of the legs are required to move in coordination with the abdomen and lower back without risk that the structural imbalances of the body will cause the forces of movement to be misapplied. When the athlete is recovering from an injury such as a stress fracture or knee damage, retro walking can be substituted to eliminate any additional degree of impact being directed into the injured area.
Retro running is a powerful sport specific training tool. Athletes such American football cornerbacks, basketball players, and tennis players must all be able to move powerfully and decisively through backward motion. Maximum speed in a retro position is essential to success in each of these sports. Training programs such as shuttle run drills, where the athlete is required to move backward and forward at a high speed within a short period of time, are effective in developing retro running skills specific to the sport.
When retro running is incorporated into a training program, the athlete can expect to obtain the musculoskeletal benefits: higher leg turn over (increased stride rate); increased stride length due to the better strength ratio between the hamstrings and the quadriceps muscles; an improved range of motion in the knee joint, which permits freer and more powerful movements in both running and jumping; creation of optimal balance between the function of the knee in the generation of the power necessary to create running motion, and the ankle/foot as the absorber of the forces generated through the running motion. Retro running requires more energy than does forward running motion; and both the ability of athlete to utilize oxygen, the VO2max as well as the heart rate of the athlete are increased through retro running training.
The incorporation of retro running into an interval running or intermittent exercise program places positive stresses on both the musculoskeletal and cardiovascular systems. Additionally, retro running stimulates the fast-twitch fibers present in the muscles of quadriceps, hamstrings, and calf. Sports science research confirms that the introduction of movements that represent a variation from regular training tend to reduce training injury rates.