Minimising the risk of ACL injuries in female athletes
Women’s sport is rapidly becoming more professional, with participation levels increasing every year. In the last few years, the awarding of full-time status for Women’s Super-league, Rugby Union, and Cricket are positive signals that Women’s sport is heading in the right direction. There is now more media coverage than ever before, and greater awareness of opportunities to be involved in women’s sport.
It is well documented in the literature that female athletes are more susceptible to knee injuries - specifically ACL injuries - than men. Why is this? And what can be done to minimise this risk?
Training Considerations:
Knee injury incidence is high in female athletes, especially in sports such as Football and Basketball (Alentorn-Geli et al., 2009), with prevalence in females ranging from 2-10 times that of males when participating in the same sport (Renstrom et al., 2008). Although these knee injuries can sometimes be due to contact between players, usually ACL injuries occur without any contact at all. Movements such as landing, cutting, and pivoting are the most common mechanisms of ACL injury (Russell et al., 2006).
The most likely causes for increased ACL injury rates in female athletes are:
Rate of force development: Females take longer to develop the same relative force level as their male counterparts.
Strength levels in untrained boys accelerates after peak height velocity (peak growth). In contrast, strength levels usually plateau for untrained adolescent girls, having implications for both performance and injury risk (Lloyd et al., 2018).
Hamstring activation deficits result in quad dominant knee function.
More ankle dorsiflexion, combined with an increase in the tendency to have a knee valgus position and external rotation of the hip on landing.
The positive news about these fundamental causes is that the risk can be reduced through structured strength training. As coaches and physios, we can help the athletes we train to develop more force (and faster), activate the hamstrings more effectively, and improve knee positioning in critical movements. Something to be aware of, though, is that in addition to the above ‘most likely’ reasons, there have been numerous other explanations, including; the different ratio of hip-width to knee position, joint laxity issues and ACL thickness (Russell et al., 2006).
Body Positioning:
Female athletes often show increased quad dominance and decreased hamstring recruitment (Hewett et al., 1996). This results in less knee flexion when landing and a heavy reliance on the quads to maintain stability. Female athletes who show reduced activation of the knee flexors (hamstrings) relative to the extensors (quads) will often land with their knees in an extended position. The weaker hamstrings are less able to limit knee extension during sporting movements such as rapid deceleration; then, as the ACL acts to resist forward movement of the tibia relative to the femur, injury occurs.
Hormonal Considerations:
Men have levels of testosterone (a hormone responsible for influencing strength and size gains) that are, on average, ten times higher than the average female (Viru and Viru, 2005). Additionally, females have other hormonal considerations, primarily the menstrual cycle and the related hormones which can influence injury, performance and musculoskeletal development. The overall injury incidence is similar to male football, although the proportion of severe injuries has been shown to be higher in women’s football (Mufty et al., 2015; Roos et al., 2017). Recent research by Martin et al (2021) studied 113 England International Football Players, with the aim to assess how menstrual cycle phases influenced the incidence of injuries over a 4 year period. Their results showed that muscle and tendon injury rates were 88% greater in the late follicular phase compared to the follicular phase, with muscle and tendon injuries/ruptures occurring over twice as often during the late follicular phase - when estrogen concentrations are highest (Stricker et al., 2006), compared to other phases. In addition, the researchers discovered that 20% of injuries occurred when athletes were “overdue” menses. A practical recommendation based on this finding, and in line with other recommendations (Martin et al., 2018; Armour et al., 2020), was that athletes/practitioners should monitor menstrual cycle length using tracking systems/applications as an “overdue” cycle is easily identified and may present an increased injury risk for the athlete.
During a normal menstrual cycle, estrogen, progesterone and some other hormones (FSH, LH) fluctuate in a set pattern over the course of an average span of 28 days. However, currently, these fluctuations are not very well understood in relation to their effects on sports performance, for example, both aerobic and anaerobic performance has been shown to vary at times throughout the normal menstrual cycle, with some studies showing both detrimental and enhanced performances during various phases of the menstrual cycle (Oosthuyse and Bosch 2010). McNulty et al (2020) suggest that a personalised approach should be taken based on each individual’s response to exercise performance across the menstrual cycle. Monitoring performances during a training phase and/or block of training to determine adaptations to the training programme is essential if maximising the athlete’s performance (in relation to the phases of the menstrual cycle) is to be achieved. Triplett and Stone (2015) suggest that the most useful advice is simply to monitor the athlete for disturbances in the menstrual cycle, which can have negative implications for healthy body weight, bone density, overall responses to training and injury potential, which will ultimately impact athletic performance.
Non-negotiables in minimising ACL injury risk:
Teach correct landing techniques: landing with the shoulders over the knees so that the centre of gravity doesn’t transition too far forwards.
Work to achieve optimal knee positions and foot contact during cutting and turning movements.
Teach acceleration and deceleration skills through structured drills.
Prioritise lower limb strength, particularly hamstring and glute strength (concentric, eccentric and isometric) through full ranges.
Athletes/practitioners should monitor menstrual cycle length using tracking systems/applications as an “overdue” cycle is easily identified and may present an increased injury risk for the athlete.
These are quite simple interventions that can significantly impact the health and well-being of both advanced and recreational level athletes. If these simple strategies can reduce the risk of ACL injuries, it is well worth investing training time to learn and improve these skills. If you would like to have a complimentary session at joint dynamics to learn more about the skills mentioned, please contact me at james.butterfield@jointdynamics.com.hk.
---
References:
Alentorn-Geli, E., Myer, G. D., Silvers, H. J., Samitier, G., Romero, D., Lázaro-Haro, C., & Cugat, R. (2009). Prevention of non-contact anterior cruciate ligament injuries in soccer players. Part 1: Mechanisms of injury and underlying risk factors. Knee surgery, sports traumatology, arthroscopy, 17(7), 705-729.
Armour, M., Parry, K. A., Steel, K., & Smith, C. A. (2020). Australian female athlete perceptions of the challenges associated with training and competing when menstrual symptoms are present. International Journal of Sports Science & Coaching, 15(3), 316-323.
BIMandelbaum, B. (2008). Non-contact ACL injuries in female athletes: an International Olympic Committee current concepts statement. British journal of sports medicine, 42(6), 394-412.
Russell, K. A., Palmieri, R. M., Zinder, S. M., & Ingersoll, C. D. (2006). Sex differences in valgus knee angle during a single-leg drop jump. Journal of athletic training, 41(2), 166.
Stone, M. H., Stone, M., & Sands, W. A. (2007). Principles and practice of resistance training. Human Kinetics.
SHOP, P., Cureton, K., & COLLINS, M. (1987). Sex difference in muscular strength in equally-trained men and women. Ergonomics, 30(4), 675-687.
Garhammer, J. (1991). A comparison of maximal power outputs between elite male and female weightlifters in competition. Journal of Applied Biomechanics, 7(1), 3-11.
Hewett, T. E., Myer, G. D., Ford, K. R., Paterno, M. V., & Quatman, C. E. (2016). Mechanisms, prediction, and prevention of ACL injuries: cut risk with three sharpened and validated tools. Journal of Orthopaedic Research, 34(11), 1843-1855.
Joyce, David, and Daniel Lewindon. "The female athlete (N. Travis Triplett and Margaret Stone)." In Sports Injury Prevention and Rehabilitation, pp. 441-447. Routledge, 2015
Lemmer, J. T., Ivey, F. M., Ryan, A. S., Martel, G. F., Hurlbut, D. E., Metter, J. E., ... & Hurley, B. F. (2001). Effect of strength training on resting metabolic rate and physical activity: age and gender comparisons. Medicine & Science in Sports & Exercise, 33(4), 532-541.
Lloyd, R. S., Myer, G., Burden, R., Blagrove, R., Montalvo, A., & Read, P. J. (2018). Applying strength and conditioning practices to female athletes. In Routledge Handbook of Strength and Conditioning (pp. 19-34). Routledge.
Malina, R. M., Bouchard, C., & Bar-Or, O. (2004). Growth, maturation, and physical activity. Human kinetics.
Martin, D., Sale, C., Cooper, S. B., & Elliott-Sale, K. J. (2018). Period prevalence and perceived side effects of hormonal contraceptive use and the menstrual cycle in elite athletes. International journal of sports physiology and performance, 13(7), 926-932.
Martin, D., Timmins, K., Cowie, C., Alty, J., Mehta, R., Tang, A., & Varley, I. (2021). Injury incidence across the menstrual cycle in international footballers. Frontiers in sports and active living, 3, 17.
Mayhew, J. L., & Salm, P. C. (1990). Gender differences in anaerobic power tests. European journal of applied physiology and occupational physiology, 60(2), 133-138.
Miller, A., MacDougall, J, Tarnopolsky, M, and Sale, D (1992). Gender differences in strength and muscle fibre characteristics. European Journal of Applied Physiology 66:254-262.
Mufty, S., Bollars, P., Vanlommel, L., Van Crombrugge, K., Corten, K., & Bellemans, J. (2015). Injuries in male versus female soccer players: epidemiology of a nationwide study. Acta Orthop Belg, 81(2), 289-95.
Otis, C. L., Drinkwater, B., Johnson, M., Loucks, A., & Wilmore, J. (1997). ACSM position stand: The female athlete triad. Medicine & Science in Sports & Exercise, 29(5), i-ix.
Padua, D. A., Carcia, C. R., Arnold, B. L., & Granata, K. P. (2005). Gender differences in leg stiffness and stiffness recruitment strategy during two-legged hopping. Journal of motor behaviour, 37(2), 111-126.
Parker, D. F., Round, J. M., Sacco, P., & Jones, D. A. (1990). A cross-sectional survey of upper and lower limb strength in boys and girls during childhood and adolescence. Annals of human biology, 17(3), 199-211.
Plisk, S. S. (2000). Speed, agility, and speed-endurance development. Essentials of strength training and conditioning, 471-491.
Pitchers, G., Elliot-Sale, K. (2019) Considerations for coaches training female athletes. UKSCA, Issue 55, 2019.
Quatman-Yates, C. C., Myer, G. D., Ford, K. R., & Hewett, T. E. (2013). A longitudinal evaluation of maturational effects on lower extremity strength in female adolescent athletes. Pediatric physical therapy: the official publication of the Section on Pediatrics of the American Physical Therapy Association, 25(3), 271.
Renstrom, P., Ljungqvist, A., Arendt, E., Beynnon, B., Fukubayashi, T., Garrett, W., ... & Engebretsen, L. (2008). Non-contact ACL injuries in female athletes: an International Olympic Committee current concepts statement. British journal of sports medicine, 42(6), 394-412.
Roos, K. G., Wasserman, E. B., Dalton, S. L., Gray, A., Djoko, A., Dompier, T. P., & Kerr, Z. Y. (2017). Epidemiology of 3825 injuries sustained in six seasons of National Collegiate Athletic Association men's and women's soccer (2009/2010–2014/2015). British journal of sports medicine, 51(13), 1029-1034.
Stricker, R., Eberhart, R., Chevailler, M. C., Quinn, F. A., Bischof, P., & Stricker, R. (2006). Establishment of detailed reference values for luteinizing hormone, follicle stimulating hormone, estradiol, and progesterone during different phases of the menstrual cycle on the Abbott ARCHITECT® analyzer. Clinical Chemistry and Laboratory Medicine (CCLM), 44(7), 883-887.
Viru, A.,& Viru, M. (2005). Resistance exercise and testosterone. In W.J.Kraemer (Ed.), The endocrine system in sports and exercise (pp. 319–338). Oxford, UK: Blackwell Science.
Oosthuyse,T.,&Bosch,A.N.(2010).Theeffectofmenstrualcycleonexercisemetabolism:Implications for exercise performance in eumenorrhoeic women. Sports Med, 40(3), 207–27.
Triplett, T.M., Stone, M (2015). In Joyce, D., & Lewindon, D. (2015). Sports injury prevention and rehabilitation. integrating medicine and science for performance solutions, 2016.