How to keep your knees healthy. Why young female and male triathletes should be trained differently.

this article was originally written for publication to young adults.

Young female athletes tend to injure the anterior cruciate ligament of the knees (ACL) more frequently than young male athletes. The role of the ACL is to prevent the lower leg from moving too far forward at the knee joint when you’re jumping, running, playing volleyball or soccer. Knee instability can lead to the overstretching of the muscle and tendons making them weak, injury to the minisci (the cushioning inside the knee), and even break down of the knee surface. Coaches and athletic trainers are now beginning to recognize that young female athletes need to be trained differently from young male athletes in order to prevent and avoid knee/ACL injuries. Until now, boys and girls were trained the same without considering the significant differences between them. Along with the obvious sex differences, there are important physical and physiologic differences that must be taken into account when developing training routines and schedules.

Young female knees are different from young males:
The higher rate of ACL injury in young women has been attributed to a combination of factors:
• A young women’s hip and knees are different in structure than young males (we tend to get wider);
• The muscles in the front of the thigh (known as the quadriceps) tend to be stronger than the muscles in the back of the thigh (the hamstrings);
• Young male athletes typically develop more muscle than young women;
• Young female athletes tend to use the strength of their ligaments (the attachments of bone-to-bone) for knee stability;
• Young male athletes tend to use their muscle strength more for knee stability;
• During adolescence, hormones (such as estrogen) are secreted that can contribute to knee laxity or increased flexibility.

The Need for Specific Strength/Weight Training for Female Triathletes
According to the American College of Sports Medicine (ACSM), the earlier young athletes are taught weight training specific to them, the better chance there is of avoiding unnecessary injuries. Strength/weight training impacts many body systems, including muscular, skeletal, neural, endocrine (hormonal), metabolic, immune, and respiratory. Resistance (weight) training increases muscular strength, joint integrity, muscle mass, bone density and bone mass, and flexibility. Resistance training also decreases muscle imbalances, decreases the rate at which muscles fatigue or tire out, and decreases abnormal muscular loads or work on the knee or hip joint. A safe, strength/weight training program specific to the physical and physiologic needs of the young female triathlete is necessary to provide her with a strong musculoskeletal base on which to build muscular strength and endurance, athletic skills, as well as prevent and reduce the risk of noncontact ACL, overuse and overload injuries. Coaches and trainers should focus on exercises that emphasize core stability and strengthening of abdominal and back muscles to help maintain proper hip alignment. Exercises should also focus on strengthening of the adductors (inner hamstring muscles) and gluteals (buttocks) as well as strengthening of the quadriceps, hamstrings, and ankle. Balance training is also key in knee stability and strength.