The PARS stress fracture (spondylolysis) usually occurs in the lower back (lumbar spine) and results from repetitive hyperextension (bending backwards) and rotation activities. This fracture is often considered an “overuse injury.”
Athletes who participate in sports or activities that involve twisting movements and backward bending are more likely to experience a PARS stress fracture. The Pars stress fracture is estimated to occur in 30% of young athletes. Sports where hyperextension of the back routinely occurs include gymnastics, diving, football (offensive linemen), pole vaulting, weight lifting, wrestling, dancing, high jumping and volleyball.
Athletic Energy Deficit (AED) is also likely to play a role in athletes who experience a PARS stress fracture. AED is an energy imbalance that results when high levels of physical activity, training or sports (energy output) are not balanced with an adequate and appropriate diet (energy input). AED often develops when there is pressure to change eating habits, particularly in some sports where a low body weight may be encouraged.
The years around puberty are a time of rapid bone growth. Girls and boys build 60% to 80% of their bone mass by age 18. During this time, pre-teens and teenagers who do not eat enough to meet their energy needs face an “energy deficit” that can impair proper bone growth and mineralization. Once bone growth is complete, PARS fractures are rarely seen.
With insufficient energy intake there may be slower bone formation and mineralization of the bone. Theoretically, insufficient energy leading to slower bone formation combined with repetitive hyperextensions of the back put enormous pressure on developing bones, making them more susceptible to fractures. Left unchecked, AED and poor bone growth may result in more stress fractures and early osteoporosis, a disease where bones become fragile and are more likely to break.