What Causes Low Back Pain?

What Causes Low Back Pain?

Low back pain is considered to be one of the most prevalent injuries in weightlifting, powerlifting, and CrossFit. Although common, there is no consensus on the most efficient way to treat this pain. This is because low back pain can be caused by many different factors. Unfortunately the vague term of “low back pain” is widely accepted and often handled the same despite different underlying causes of the pain.

My goal today is to help explain three different causes for low back pain in athletes. These include:

  • Muscular Strains
  • Spondylolysis
  • Disc Injuries

Finding the Source

Before we jump into the different diagnosis of low back pain injuries and how to tell them apart, we need to understand the source of WHY these problems occur in the first place.

Muscular Strain

Muscular strains are some of the most common types of injuries that occur during weight training (2). In fact Gregg Calhoon and Dr. Andrew Fry found that muscular strains accounted for 74.6% of the back injuries sustained by weightlifters over a 6-year period (1). The good thing is that these types of injuries are usually not very severe. In fact, 87.3% of the time, these weightlifters that complained of this type of injury only missed one day of training (1). 12.7% were found to only miss less than one week.

Exericse Push (4)

So what is a muscular strain? It’s actually a small tear of the muscle. When excessive strain is placed on a muscle as it is contracted or stretched during a barbell lift, it can lead to tiny tears in the fibers that make up the muscle. Within 24 hours of the injury, inflammation and pain set in. Swelling occurs as the body attempts to heal itself and the injured muscle becomes considerably weaker (10). After 48 hours, strength of the muscle usually returns to normal after swelling decreases.

Example of a small tear in the muscle fibers. From “Diagnostic Imaging in Muscle Injury” by Massimo Manara, Danilo Manari and Giulio Pasta


Historically, one of the most serious back injuries for weight lifters is spondylolysis. Spondylolysis is a stress fracture of the spine. It occurs at the pars interarticularis usually around the 5th lumbar vertebrae.

Spondy .jpg

Mechanically, this area absorbs a significant amount of force, especially if the low back is in an extended or arched position (called lumbar lordosis). Repetitive loading of this area with an extended spine over time is thought to be the main cause of developing this injury. If left unchecked, this stress fracture can lead to the much more serious problem, spondylolisthesis (anterior sliding of the spinal vertebra).

Spondylolysis .jpg

So how prevalent is this injury? Research has shown that only 4-7% of people ever sustain this injury. However, we’ve also found that these numbers may slightly increase in athletes. This has been especially true for those who participate in strength sports like weightlifting and powerlifting.

After following 26 Japanese weightlifters for several years, researchers found 24 of 26 to have recurrent back pain. Eight (31%) of these athletes were found to have spondylolysis (3). Another group of researchers studied 27 weightlifters and 20 powerlifters and found twenty one (44%) to have spondylolysis (4). No significant difference was found between the weightlifters and powerlifters in this study.

Spondy Pic.jpg
A CT image of a spondylolysis fracture

These studies would therefore suggest that barbell sports produce a higher incidence of this serious injury! However you must understand a few key points of these research articles before jumping to any conclusions.

First, research has shown that spondylolysis is strongly influenced by your genetics (5). That means some of us are unfortunately pre-disposed to having this injury.

Second, every one of the studies that observed this injury among weightlifters did so before 1972. Before this time, the clean and press was an official lift used in competition. The pressing portion of this lift was usually performed with considerable hyperextension of the lower back. Performing this repeated motion while pushing tremendous weight likely led to the high percentage of documented spondylolysis injuries (2). While there is still risk for sustaining this injury when participating in these sports, the probability is probably much lower than has been reported in past research.



Disc Injury

The last injury we will discuss is dis bulge (or herniation). While this injury is not extremely common for a youth athlete, research has shown adults are still at risk. Science has shown that 11% of back injuries with youth athletes compared to 48% of adults were attributed to disc abnormalities (8).

So how do injuries to the spinal discs occur? Repetitive spinal flexion and extension under load is most likely the cause of disc injuries. The annulus fibrosis (outer layer of the disc) may tear. Afterwards, the inner jelly (or nuculeus pulposis) leaks out and can press onto a nerve. Usually this leads to severe pain in the lower back or cause radiating pain down the leg (9).

Disc herniation .jpg

The problem with this diagnosis as the MAIN cause of back injury is that there is NOT a very clear relationship between disc issues and pain. For example, research has shown multiple times that completely healthy people can have disc issues (including herniation bulges) (6).

Recently Dr. Scott Boden and colleagues performed MRIs on 67 individuals who had never had low back pain (6). What they found would amaze many of you. They found disc degeneration or bulges in 35% of the study participants of ages 20-39. Of those less than 60 years old, 20% had a completely herniated disc without any symptoms!

Another group of researchers looked at individuals who never had low back pain. The researchers found that 19.5% of under-40 year old group had a disc herniation (7). In other words, 20 percent of young adults may have a disc herniation and are walking around with no symptoms whatsoever!

Final Thoughts

So what do these studies mean? While many of us today may likely have structural issues in our spine, they may not be the main cause of back pain. Most injuries to the low back while weightlifting, powerlifting or participating in CrossFit are found to be short-lived strains of the surrounding muscle and fascia.

That being said, more serious issues (such as the spondylolysis and disc herniation) can still develop slowly over time. These injuries, while less common, still need to be on the radar of coaches and medical professionals. If left unchecked, these issues can turn into big problems very quick!

To truly determine the cause of back pain, proper screening is crucial. In part 3 of this series, we will discuss a few easy screens to help differentiate between the types of injuries we discussed today. This will allow you to better understand if the pain your feeling is something you can easily manage on your own or if it’s something that needs to be checked out by a medical professional.

Until next week,

Dr. Aaron Horschig, PT, DPT, CSCS, USAW


Kevin Photo
Dr. Kevin Sonthana, PT, DPT, CSCS



  1. Calhoon G, & Fry AC. Injury rates and profiles of elite competitive weightlifters. Journal of Athletic Training. 1999l34(3):232-238
  2. Stone MH, Fry AC, Ritchie M, et al. Injury potential and safety aspects of weightlifting movements. Strength and Conditioning. 1994 June; 15(3):15-21
  3. Katani PT, Ichikawa N, Wakabayashi W, et al. Studies of spondylolysis found among weightlifters. Br J Sports Med. 1971 Nov; 6(1):4-8
  4. Dangles CJ & Spencer DL. Spondylolysis in competitive weightlifters. J Sports Med. 1987;15:634-635
  5. Yochum TR & Rowe LJ. The natural history of spondylolysis and spondylolysthesis: Essentials of Skeletal Radiology. T.R. Yochum and L.J. Rose, eds. Baltimore: Williams & Wilkins. 1987;243-272
  6. Boden SD, Davis DO, Dina TS, et al. Abnormal magnetic-resonance scans of the lumbar spine in asymptomatic subjects. A prospective investigation. The Journal of Bone and Joint Surgery. 1990 March; 72-A(3):403-408
  7. Wiesel SW. Tsurmas T, Feffer HL, et al. A study of computer-assisted tomography: I. The incidence of positive CAT scans in an asymptomatic group of patients. Spine. 1984 September; 9(6):549-51
  8. Micheli LJ & Wood R. Back pain in young athletes. Significant differences from adults in causes and patterns. Arch Pediatr Adolesc Med. 1995 Jan;149(1):15-8
  9. Mortazavi J, Zebardast J, & Mirzashahi B. Low back pain in athletes. Asian J Sports Med. 2015 June;6(2):e24718
  10. Nikolaou PK, Macdonald BL, Glisson RR, et al. Biomechanical and histological evaluation of muscle after controlled strain injury. The Americal Jouranal of Sports Medicine. 1987; 15(1): 9-14

Published by

Dr. Aaron Horschig

Doctor of Physical Therapy, CSCS, USAW coach and athlete.

8 thoughts on “What Causes Low Back Pain?

  1. Hey Aaron,

    I’m a 19 year old Olympic weightlifter and have recently been diagnosed with servere pars defect and spondylolisthesis. It’s caused terrible nerve pain down my right leg along with my glutes constantly being tight and my hip flexors feeling like they have tennis balls in them. Could you possibly do a post about how to overcome this injury or what stretches help to relieve the pain in these areas. I’m also unsure if I should be doing any overhead work or movements which involve me hyperextending my back given to me by my osteopath.

    According to my surgeon I’ve had this injury for longer than 4 years but its only become promin since I started weightlifting. Please can you give me some advice?


    1. Stef! Thanks for the message! This can be a very difficult injury to work with. During this series on low back pain we will be covering ways to rehabilitate however I strongly suggest finding a sports physical therapist who can really give you the hands on help you need to effectively treat this injury. The most important part of this injury is learning to brace your core properly (things we have discussed in previous posts), however every athlete will also have individual needs that must be considered and worked on in order to effectively treat the problem – a physical therapist can help with this.

      Liked by 1 person

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