While competitive diving is certainly not new, the complexities of diving injuries are still little understood. Nathaniel S. Jones, M.D., CAQ-SM, a family medicine and sports medicine physician with the University of Loyola School of Medicine in Maywood, Illinois, hopes to change that with his article, “Competitive Diving Principles and Injuries,” published in the September/October 2017 issue of the Current Sports Medicine Reports.
Jones told OTW, “Most of the aquatic sports literature has to do with swimming, and although it has been improving, diving literature is still limited despite its continued popularity especially in the Olympics.”
According to Jones, while the 2016 consensus statement on the proper methodology of data and injury collection during aquatics championships in FINA (International Federation of Swimming) published in the British Journal of Sports Medicine in May, 2016, has made tracking injury information easier, there is still much work needed to be done on understanding the mechanics of diving injuries.
What We Do Know
What we do know so far comes mostly from a handful of recent studies, according to Jones. One study, “Epidemiology of National Collegiate Athletic Association women’s swimming and diving injuries from 2009/2010 to 2013/2014” published in the British Journal of Sports Medicine in 2015 looked at National Collegiate Athletic Association (NCAA) swimming and diving injuries from 2009 to 2014, where the researchers found an injury rate of 1.94 injuries per 1000 athlete exposures (AE) for males and 2.49 injuries per 1000 AE for females. They also found that more injuries happened during practice than competition.
In another study published in the American Journal of Sports Medicine in September 2009, researchers collected data on divers in the 2008 Olympics and found that 2.1% of them were injured during the games. A higher injury rate was found in another study on the 2012 Olympics—“Sports injuries and illnesses during the London Summer Olympic Games 2012” –where 8.1% of the divers were injured, suggesting either an increase in injury rates or an improvement in data collection. Another study he mentions—“Injury and illness in aquatic sport: how high is the risk? A comparison of results from three FINA World Championships compared injury during the (FINA) World Championships of 2015, 2013, and 2009 and found that older athletes were at the highest risk of injury.
The Physics of Diving
Jones suggests that it is the uniqueness of the sport that makes understanding competitive diving injuries such a challenge. He told OTW, “Diving injuries are more attuned or comparable to gymnastic injuries. Although a lot of time is spent practicing dives there is also a lot time spent with dry land training which involves tumbling, which is very similar to gymnastics. In addition, there are very few other sports, if any, in which the athlete is exposed to the speed and forces that divers experience especially when talking about the 10m platform dives.”
According to Jones, “A 10m platform diver can reach up to velocity of 16.4 m·s-1 (36 mph) before entering the water with quick deceleration to 33 km·h-1 (20 mph) on impact with water, with a force of about 400 kg·N-1. Thus, the impact at the water surface on the diver can reach 2.0 g to 2.4 g. A 1-m springboard dive reaches an average peak velocity of 8.4 m·s-1 (30.1 km·h-1 or 19 mph). Upon water impact velocity is decreased by greater than 50% within a fraction of a second.”
He wrote that “these incredible velocities and impact forces are thought to be large contributors to competitive diving injuries” and that “with such forces, injuries can occur not only in the setting of a dive gone wrong, but also more commonly secondary to an accumulation of exposures to repetitive forces.”
“These principles of the physics of diving,” he said, “are vital to understanding the nature and cause of many of competitive diving injuries.”
The Diving Mechanics and Resulting Musculoskeletal Injuries
Competitive divers train about 40 hours a week. Springboard divers average usually 100 to 150 dives a day while platform divers average about 50 to 100 dives per day. Between the impact forces on the body and the constant repetition of movement, injury can happen in any of the phases of the dive.
The first phase of the dive of course is the take-off from the diving platform which includes the approach, hurdle (where the diver jumps on to the end of the board) and the press (the depression of board and the upward acceleration of the diver’s body). If the timing of downward motion of the board with the downward motion of the diver onto the board is not perfect, the diver is at high risk of lower-extremity injuries, especially of the knee.
Most common lower extremity injuries, according to Jones, are patellar tendinopathy, quadriceps tendinopathy and patellofemoral compression syndrome. The combination of overtraining on the board and on dry land can also lead to Achilles and posterior tibialis tendinopathy. If an athlete performs an arm stand dive off the platform, then they are also at risk for upper-extremity injuries.
The second phase is the flight or midair maneuver which begins as soon as the diver leaves the board and ends when he or she hits the water. The common injuries during this phase are spine and long head of biceps injuries to torsional overload if a diver does a twist in the area. Concussions and fractures can also occur during this phase if the diver hits the board midair, but this is less common.
The third phase is the entry phase when the diver makes impact with the water. This is the phase where most injuries, both traumatic and overuse, tend to occur due usually to the combination of decelerating forces (more than 50% decrease in force in less than second) and poor dive technique.
Shoulder injuries often happen during the third phase. Jones wrote, “Many times, the shoulder is the endpoint of the deceleration forces from water entry impact. The shoulder absorbs much of the water entry axial loading, taking the brunt of the kinetic chain load.”
He added, “It is imperative to stabilize the glenohumeral joint by elevating the shoulder girdle with increased scapular abduction so the glenoid fossa is behind the humeral head therefore providing better absorption of the axial load impact. When the glenohumeral joint is in 180 degrees of abduction and flexion and maximal internal rotation with no inferior support from the glenoid fossa, the shoulder is in a mechanically at risk position. Decreased scapular abduction impairs energy dissipation and increases the demands on the soft tissue, such as the rotator cuff, biceps tendon and labrum leading to injury, ligament laxity, and many times to shoulder instability.”
Athletes with weak or unstable shoulders tend to overcompensate with increased forces on the spine, but that just puts them at increased risk for spine injuries as well. Lumbar spine injuries, according to Jones, are the most common reason that competitive divers retire. He cites recent studies that show the incidence of low back pain in divers to be between 38.4% and 89% and that divers after the age of 13 years have a 45% chance of experiencing back pain within a year.
Pay Attention to Pediatric Divers
Jones emphasized that special attention needs to be paid to young divers because a growing spine is at greater risk for trauma, especially during the growth spurt that occurs during adolescents.
He told OTW, “The average age of a typical Olympic caliber diver is between 14 and 30. So especially at the beginning of their careers their bodies are still developing and at higher risk for injury due to the increased forces. Also their strength is still developing and so they become fatigued more easily making them susceptible to over use injury.”
He added that “young divers are still learning technique and form and especially as it relates to the back even a slight increase in extension in their form increases back pain occurrence.“
Jones also called for future research to focus on the large forces that are created and then abruptly dissipated with water entry, and the repetitive exposure to these forces. He said the research should focus not only on how to minimize these forces, but also on how to reduce exposure to them.
I am confused by Dr. Nathaniel Jones’ use of the expression “force of about 400 kg·N-1” in the paragraph Physics of Diving, meaning 400kg/Newton (since I can’t reproduce the -1 in the article as an exponent on my keyboard). It was my understanding that (per Wiki definition), “The newton is the unit of force in the International System of Units. It is defined as 1 kg⋅m/s², the force which gives a mass of 1 kilogram an acceleration of 1 metre per second per second.”
Thus, dividing kilograms by 1 Newton, as stated in article, does not appear to be a unit of force. Am I mistaken?
Thank you for any clarification. JP