Why Do Females Incur More ACL Injuries – Act 31
For over 30 years, it’s been frustratingly known in the sports orthopedic community that female athletes have a greater risk of anterior cruciate ligament (ACL) tears of the knee. Early thoughts were that there were skeletal structural differences in males’ and females’ knees; then that it was hormonal; then neuromuscular, etc. We have covered many of these potential causes here and here as well as how to mitigate risk here and here. The research supports all of these to some degree but others are seeking the Holy Grail in what we can do to prevent these often career-ending and potentially arthritis-preceding injuries.
A recent Australian study compared strength and biomechanical differences among elite female soccer and Aussie Rules Football players prospectively to see which ones elevated athletes’ risks.
Strength measures included isometric hip adductors and abductors, and eccentric (muscle lengthening) hamstrings. Biomechanical variables included standing jump kinetics and single-leg hop kinematics, both of which the research suggests are indicative of biomechanical flaws that could predispose athletes to injury. The study period was 18 months.
Only 15 injuries occurred among the nearly 300 athletes. Prior ACL injury was the strongest predictor. Having a lower isometric adductor/abductor ratio doubled the risk. Interestingly, a stronger jumping take-off force had a positive odds ratio, perhaps because the quad strength was so dominant in the better jumpers.
The thinking was that, since athletes want to maximize power during jumping, they need to minimize “other modifiable factors such as decreasing joint loads or increasing the contribution of [other] muscles” than the quads.
Between-leg strength asymmetries of 10%-20% also did not factor into risk. So what’s the best way to avoid an ACL injury – don’t have a prior one!
MSSE Aug. 2022
Weight Loss and Sleep: A 2-fer Worth Striving For
While the exact causes for the steep rise in obesity rates in the US and around the world are unknown, population data is harrowing: ~33% of adults are obese, ~33% of adults are overweight, and ~20% of kids ages 2-19 are obese. Alone, extra weight might carry social, psychological, and quality of life consequences, but medically the costs and long-term consequences can be devastating. Whether due to the introduction into the American diet back in the 1950s and 1960s of trans fats, high-fructose corn syrup, or junk food in general; or the advent of home and work environments that ease the burden of having to move our bodies too much, the rise in overweight/obesity is a burden on those with the excess weight and on the society in general.
A recent study found that simply adding 2 hours of sleep/night actually provides an impulse to weight loss by creating a “negative energy balance” without a concomitant increase in energy expenditure.
That means that by adding ~1.2 h/night of sleep (not just lying in bed), participants ate about 270 calories less/day over the 2 week study. This calculates to a 162 cal/day deficit for each additional hour of sleep/night, amounting to ~0.87 kg (1#) loss over the 2-week study period which approximates a 12 kg (26.4#) loss over 3 years!
Being the first real-world, not-in-a-lab study of this sort, the findings are especially noteworthy. The implications are obvious: figure out a way to get to bed early and sleep longer, so your body can live on fewer calories…and live longer and healthier.
JAMA Int Med Apr. 2022