Alternative Pop-Up for Surfers with Low Back Pain

Abstract

Surfing is enjoyed by many people around the world. A common problem in surfers is back pain during the “take-off,” specifically the “pop-up.” This article describes each part of the “take-off, and introduces an alternative to the “prone pop up” - called the “knee pop-up.” This alternative is a suggested technique to alleviate the stress in the lumbar spine during surfing.

PROBLEM

Surfing is enjoyed by millions of participants on coastlines throughout the world. Unfortunately, many surfers are also plagued by back pain that hinders or terminates their participation in the sport. Acute and chronic injuries of the low-back are among the most common reported in surfers.1–3 In fact, back spasms are reported to be the most frequent cause of impairment among surfers3 with competitive, aging, or big wave surfers the most likely to be injured.2

The “take-off” has been identified as the component of surfing where low back injuries are frequently reported to occur.2 The take-off includes paddling to “catch” a wave, the “pop-up,” and the “drop-in.”

Pop-up is a term used to describe the movement of quickly going from a paddling position to standing on the surfboard after catching a wave. The type of pop-up most commonly used is initiated from a prone position while the surfer is paddling down the face of a wave. The surfer pushes off of the board with his/her distal thighs to project upward and forward to a crouch standing position. This position is referred to as the “prone pop-up.” The prone pop-up is the style of pop-up that most surfers associate with back pain while surfing. The kinematic events and subphases that comprise the prone pop-up are illustrated and labeled in Figure 1.

Figure 1:

Sequential photos of the prone pop-up with annotations indicating key events. Abbreviations: Upw. Acc. = Upward Acceleration; Fwd. Wt. = Forward Weight

SOLUTION

An alternative to the prone pop-up is the knee pop-up where the starting position is kneeling. The knee pop-up proceeds as the surfer pushes off of the board with his/her feet to hop up to a standing position. The kinematic events and subphases that comprise the knee pop-up are illustrated and labeled in Figure 2.

Figure 2:

Sequential photos of the knee pop-up with annotations indicating key events. Abbreviations: Upw. Acc. = Upward Acceleration; Bkw. Wt. Shift = Backward Weight Shift

Some surfers with back pain report that they prefer the knee pop-up because it causes less pain or is less likely to exacerbate their low back symptoms. It is important to note that to use the knee pop-up a surfer must be surfing on a “long board,” rather than “short board” because the short board has a tendency to sink while paddling from a kneeling position.

USE IN PHYSICAL THERAPY

Clinicians with patients who are surfers with intermittent low back pain can recommend the knee pop-up to prevent re-injury or exacerbation of symptoms. When patients with existing symptoms insist on surfing in spite of their back pain, the knee pop-up is an alternative to consider that might make surfing more tolerable.

As an adjunct to a recommendation to convert to a knee pop-up, the clinician might also consider testing surfers for adequate flexibility for the pop-up task and implementation of a program of flexibility exercises where indicated. An example of a test with flexibility requirements similar to a pop-up is illustrated in Figure 3. To have adequate flexibility for a pop-up, the surfers should be able to hop forward from a push-up position to a landing position where their toes come even with a line connecting the heels of their hands, without lifting the hands from the floor. Often, active hip flexion range of motion is the limiting factor for individuals who have difficulty completing this functional test.

Figure 3:

Test to predict adequate flexibility for successful pop-up. The subject should be able to hop forward so that both feet land even with the heels of their hands while keeping the hands flat on the floor.

A second adjunct to the knee pop-up should be consideration of a lift under the hands to increase clearance under the body, thereby, making the pop-up task easier. An example of lifts fabricated by the authors is illustrated in Figure 4. These lifts are made of molded silicone with a suction-cup bottom to mount them to the upper surface of the board. The effect of these 2-inch lifts is evident by the flexibility test conducted with the lifts in Figure 5. The lifts provide increased chest clearance, allowing the subject to more easily finish the pop-up with his/her feet under their center of gravity.

Figure 4:

Surfer demonstrating a pop-up with lifts.

Figure 5:

Flexibility test demonstrating the effect of lifts (compare to Figure 3).

Finally, as an alternative to any pop-up, clinicians might also consider recommending use of a long-shaft paddle. This allows the surfer to paddle and catch a wave from a standing position, therefore, eliminating the need to pop-up altogether. This style of surfing is called “stand up paddling” (SUP). An example of a long-shaft paddle is shown in Figure 6.

Figure 6:

Surfer demonstrating stand up paddling technique.

DISCUSSION

To better understand the biomechanics of the prone popup we measured some of the kinematic characteristics of an experienced surfer performing the prone popup under laboratory conditions was performed. Selected kinematics during and between prone and knee pop-ups performed by a male surfer on a “dry land” surfboard were quantified and compared. A magnetic field-based motion measurement system with sensors placed at T12 and S2 provided data on sagittal plane lumbar spine movement. Data were sampled at a rate of 100Hz and are illustrated in Figure 7. Key characteristics of the prone and knee pop-ups are listed in Table 1.

Figure 7:

Comparison of forward and backward bending kinematics of the lumbar spine during knee and prone pop-ups

Table 1.

	Prone Pop-up	Knee Pop-up
Maximum Lumbar Spine Extension Angle	4° hyperextension	0°
Maximum Lumbar Spine Flexion Angle	37°	36°
Peak Flexion Velocity	351°/s	131°/s
Peak Flexion Acceleration	7128°/s2	3110°/s2
Flight Time	0.2s	0.2s

These data document the relatively high acceleration rate required for the prone pop-up task in comparison to the knee pop-up. The high acceleration of a prone pop-up is a likely factor that explains the risk for low back pain and injury associated with it. This belief is based upon the physical relationship between acceleration and the corresponding forces and torques required. The high accelerations in a prone pop-up can be expected to require very high forces and the correspondingly high stresses. The relatively lower accelerations of the knee popup are likewise probably associated with much lower stresses.