BRINGING SCIENCE TO TREATMENT

Ice skating injuries: be knowledgeable about knees!

Tracy Ward explores ice-skating injuries, which are common in athletes with rigorous training schedules. Which injuries are most common, and how can they be prevented?

2019. Russia’s Alexandra Stepanova and Ivan Bukin in action. REUTERS/Issei Kato

Figure skating injury rates have increased in recent years. This is perhaps not surprising; a sport that demands athletic, technical, and artistic excellence will inevitably place new challenges upon elite skaters to defy existing boundaries. Data shows a similar proportion of acute and overuse injuries. The majority of overuse injuries are seen in the singles category (likely due to the extreme technical demands and grueling training hours required). Acute injuries, however, are more prevalent in pairs, ice dance, and synchronized skating disciplines, where collisions and reliance on partners contribute to more traumatic injuries.

In terms of injury location, lower-limb injuries are much more prevalent than upper limb injuries – across all disciplines of figure skating. In most sports, the lower limb muscles absorb the ground reaction forces to soften the impact transmitted up the kinetic chain. However, the stiff and rigid boots worn by ice skaters make it almost impossible to execute a soft ankle landing. As a consequence, the ankle joint is the most strained joint overall, and patellar tendonitis is the most common overuse injury in all categories(1).

The knee is at high risk of injury because it provides a gateway, transferring forces from the foot and ankle in the lower half of the limbs, to the hip, pelvis and lower back higher up. Any imbalances or injuries experienced above or below the knee will have an impact on the knee joint itself, so it is potentially subject to stress from both directions. Niggling overuse injuries often do not prevent a skater from training. Thus skaters continue to skate with minor injuries which often persist and worsen – eventually becoming a complex issue affecting more than one area, particularly if compensation strategies have formed.

The importance of technique

Regardless of the discipline, ice skaters use muscles around the knee joint to create power and momentum across the ice. The basic stroking (gliding forwards) technique relies on the skater bending down at the knees and then pushing with one foot to strike off and propel forward. Continued momentum is achieved by rising at the knees and then sinking again while the other leg pushes off the ice. This continued motion creates thousands of repetitive knee bends during a training session, replicated many days a week. It also occurs during off-ice training, where the skater will practice their jumps and elements on the ground.

Jumps are the primary element of figure skating. They are initiated with speed and positioning to build angular momentum, and then by pushing down on the ice through the knees – to generate the force to take off with sufficient vertical velocity. This push also creates rotational momentum for turning in the air. Landings are often from a great height (see figure 1) and very fast, giving very little time to absorb the jump forces, which can be between five and eight times a skater’s bodyweight. The significant landing forces, in conjunction with the lack of articulation in the boot, give the skater minimal time to distribute the landing forces – and thus it is directly transferred up through the lower limb to the knee and hip(2).

Figure 1: Ice-skating jumps

Japanese Olympic men’s figure skater jumps high, suggesting high loading forces through the ankles and knees during the subsequent landing(3).


Knee Injuries in ice skating

On-ice knee injuries are divided into those directly affecting the knee, and indirect injuries, where the knee pain occurs secondarily to other problems.

  1. Direct

The repetitive knee-flexion motion most likely causes conditions such as patellar tendonitis and general anterior knee pain syndromes. Acute conditions such as meniscus (cartilage) damage or ligament tears are less common unless there has been excessive force and trauma. Muscle strains occur due to poor landings after jumps, or from overstretching on footwork (with the hamstring muscles most likely affected).  Overstretching movements, which involve extreme flexibility through the lower limb, are often regarded as the most visually pleasing. Therefore, skaters may reach beyond their limits to please the judges in competition. The hamstrings, which also eccentrically control the skater throughout their routine, become vulnerable due to the constant acceleration and deceleration motions.

Since a skater usually jumps with the same foot, lands with the same foot, and performs their more complex movements with a favored foot, muscle imbalances and asymmetries frequently develop. In particular, a weakness in the quadriceps muscles can lead to patellar subluxations and dislocations when placed under excess weight.

  1. Indirect

The extreme flexibility demands of figure skating can cause instability around the hip joints (as the soft tissue becomes lax in accommodating this larger than normal range of movement within the hips). The lack of stability in the hip joint creates excess load transfer to the knees. Because of the varied skating and landing positions, loads may be distributed indirectly, resulting in an additional force applied to one side of the knee, instead of evenly spread through the joint.

A skater relies heavily upon a strong core to absorb rotational forces and transmit them correctly through the body. A weak core or hip musculature may cause an inefficient transfer of load to the knee joints.

Finally, excessive back bending into lumbar extension positions for various poses and skills requires strong gluteal and lower limb musculature to support the skater. A weakness found anywhere in the core, glutes, or leg muscles will force the knees to bend further or move anteriorly. The resulting pressure on the patella and surrounding tissues helps compensate for the lack of range of motion, improves balance, and prevents the skater from falling. Increased forces on the anterior knee also can cause pain and injury to the patellar tendon.

Injury prevention in skaters

Preventative strategies involve strengthening the muscles around the knee joint and the hip joint to gain additional power for pushing movements. Continued strength gains may help avoid injury, as well as allow performance enhancement, and there is some research to link increased muscle mass of the legs (particularly hip and knee musculature) to increased jump heights(4)– thus showing a direct correlation between strengthening the knees and performance.

Other research has also demonstrated that the addition of plyometric exercises to strengthen the leg muscles increases time in the air with jumps, giving overall better jump execution(5). Collectively these elements could extend the longevity of a skater’s career. Here are some suggested exercises for skaters wishing to build resilience and reduce the risk of injury (see figures 2-4). Begin with 10 repetitions on each leg and aim for 3-4 sets each side.

Fig 2: Single leg squat, for knee strengthening and power to push off for jumps.

The skater lowers down on one foot, hips back behind, keeping the knee in line with the big toe. Push through the heel to return to the standing position.


Fig 3: Banded exercise; for gluteal strengthening and power to push on stroking

Left = start position; Right = finish position

Start with feet parallel in a narrow squat position and a resistance band around the legs. Extend one leg out to a 45-degree angle (to replicate the stroking action in skating), while simultaneously bending the supporting leg. Continue to drive the stroking leg out to full extension then return to the start. Repeat with the opposite leg.


 Fig 4: Jump lunges for plyometrics training

Start with feet staggered one in front of the other, in a split-squat position. Bend both knees to lunge down, then jump up and change feet to land with the opposite foot in front. Repeat alternating legs each time.


Summary

Here are the main points that clinicians and coaches should bear in mind when considering ice-skating injuries:

*Ice skating techniques demand extensive work involving the knees to move across the ice, gain momentum, push off into jumps, and control landings.

*Knee injuries predominantly occur from overuse rather than acute trauma, with patellar tendonitis being the most common overuse injury.

*Knee injuries can often occur indirectly as a result of weaknesses elsewhere – mainly weakness in the core, lower back, and hips.

*Preventative strategies involve strengthening the lower-limb muscles with a regular strengthening program involving pushing, sliding, and plyometric based exercises to challenge the muscles appropriately for the sport. 

References

  1. Sports Health.2018 Nov-Dec; 10(6): 532-537.
  2. Orthop J Sports Med. 2015 Jul; 3(7): 2325967115596517. Published online 2015 Jul 28. doi: 10.1177/2325967115596517
  3. https://timedotcom.files.wordpress.com/2018/02/shoma-uno-olympic-japan-2018-skating.jpg
  4. J Strength Cond Res. 2010;24(3):831-839.
  5. Int J Exerc Sci. 2014;9(2):175-186.
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