Hollow back – Increased lumbar lordosis

To begin with, A hollow back describes the presence of a more than normal curved lumbar spine. A hollow back posture in the lumbar spine corresponds to an increased lumbar lordosis or hyperlordosis. In the article, I explain what “more than normal curved” means and show you what exactly is meant by a hollow back. For us to be able to answer this well, it makes sense to first look at what characterizes a posture that is typically considered healthy. I therefore recommend that you read the article regarding Postural assessment first. The article describes a “normal” or “healthy” posture. To understand this article, it is also a good idea to read the article Spine anatomy – Structure of the spine beforehand. But now let’s look at what is meant by hyperlordosis of the lumbar spine. 😉

What is unique about the spine?

The alignment of the spine seems to be of essential importance to be able to contribute to the long-term optimal functioning of the neuromuscular system, especially in the trunk area, but also beyond.1 The spine is not only responsible for protecting the spinal cord but also for protecting it also influences locomotion to a large extent.2 The spine with the shoulder girdle, ribs, and pelvis forms the “core”.3,4 The core includes both the active and the passive components of the musculoskeletal system.4

As a central axis, the spine should have specific characteristics to meet the special needs of everyday and sporting stress. The curvatures in the different areas of the spine play a decisive role. On the one hand, the curvatures contribute to the fact that pressure acting axially on the spine can be absorbed. On the other hand, an appropriately aligned spine can support the connected neuromuscular system to work efficiently. If lordosis and/or kyphosis are more or less than “normal”, the overall stability of the spine can be impaired.2 If you want to refresh your knowledge of the spine, I recommend the article “Spine anatomy – Structure of the spine”.

Hollow back – What is an increased lumbar lordosis?

With its “normal” lordosis, the lumbar spine is important, especially since it is also in direct contact with the pelvis. The typical curvature in the lumbar spine helps resist compressive forces caused by gravity. In addition, a “normal” level of lumbar lordosis appears to protect the posterior ligaments of the spine from excessive stress. Furthermore, vertically acting forces are absorbed by the curvature.5

hollow back is an increased lumbar lordosis
Fig. 1: Left “normal” posture; Right “sway back posture”

A hollow back is generally referred to when the curve in the lower back is more significant than usual (see figure 1). The abdomen is often arched forward. A hollow back can also affect the statics of the entire spine.

As mentioned above, a hollow back is called “hyperlordosis” (Greek “hyper,” ≙ “over”, “more than”).2,6 It is often not just the lumbar vertebrae responsible for an increased lumbar lordosis.7–10 To assess the lumbar spine (or generally also the overall statics of the spine), however, more than just one section of the spine, in this case the lumbar spine, should be used. This is because the individual sections of the spine are connected to each other and the pelvis. The position of the pelvis to the spine is of essential importance. If you look at the body from the side, you look at the sagittal plane. The spine’s balance within this sagittal plane can be disturbed due to structural and postural malpositions.7 The spine statics is assessed with X-rays from the side (very precise). Nevertheless, posture assessment can also be done using live visual findings or photos/videos. In the linked article, I will show you how to assess your posture without an X-ray. The angles shown in the following text always describe the angles observed when people are standing. When sitting, the characteristics of the curvature of the spine are, of course, different.

The following factors, for example, can play a role when lumbar lordosis is increased:

  • Lordosis angle
  • Pelvic incidence

Hollow back – Lumbar lordosis angle

The “normal” lordosis angle is not a fixed value. Instead, it is an area that, on the one hand, is present in asymptomatic people. So, for people who have no back problems or pain. On the other hand, it is an angle range believed not to stress structures in the spine unduly and helps keep the neuromuscular system working efficiently.2,6 A lumbar lordosis angle can be measured in different ways. The angle can affect different spine sections to determine the lumbar lordosis angle; the angle between lumbar vertebrae 1 and sacral vertebrae 1 (L1 – S1, see Figure 2) is often used. You measure from the top plate L1 (top of the vertebra) to the base S1 (top of the vertebra).11 Alternatively, you could measure the angle between lumbar vertebrae 1 and lumbar vertebrae 5 (L1 – L5, see Figure 3). You measure from the cover plate L1 (upper area of ​​the vertebra) to the base plate L5 (lower area of ​​the vertebra). The extent of the lumbar lordosis depends on various factors, such as the measurement method and age.11,12 In addition to the measurement variants just mentioned, there are others that I will not go into further in the article.

hollow back is an increased lumbar lordosis
Fig. 2: Two methods for determining the lordosis angle. Left: angle between L1-S1; Right: angle between L1-L5

Below are reference ranges of lumbar lordosis for healthy people of different ages. If the lumbar lordosis angle is above this range, one could speak of an increased lumbar lordosis.11


  • L1-L5: 34.5°-44.8°
  • L1-S1: 41.7°-54.1°


  • L1-L5: 39.8°-45.6°
  • L1-S1: 51.9°-59.1°


  • L1-L5: 38.1°-45.6°
  • L1-S1: 54.2°-61.7°


  • L1-S1: 56.6°-65.9°

Hollow back – Pelvic incidence

As already described above, however, the lordosis angle alone should not be used to assess the statics of the spine. It also makes sense to look at the extent of the thoracic kyphosis. However, I will go into more detail about the kyphosis of the thoracic spine in a forthcoming article. Now let’s look at the “Pelvic incidence”.

The pelvic incidence is an individually varying morphological constant of the pelvis and describes the position of the sacrum in the pelvis geometrically and thus provides information about the pelvic position itself.7 Essentially, it is about the relative position of the base of the sacrum to the center of the hip joint axis.8,12,13 The hip joint axis is also called the “bicoxofemoral axis” and corresponds to the line connecting the centers of both femoral heads.14 The pelvic incidence is given as an angle (see Fig. 3). Two lines are required to determine the pelvic incidence angle. A line runs vertically through the center of the base of the sacrum. The other line runs from the center of the hip joint axis through the center of the base of the sacrum and intersects the first line. The pelvic incidence also changes depending on how the sacrum and pelvis are aligned. Consequently, the pelvic incidence influences the lumbar lordosis and the spinal column statics.7,8,12,13 The formula applies:7,8,12,13

  • PI = SS + PT
    • PI, Pelvic Incidence; SS, sacral slope; PT, Pelvic Tilt

There are two new parameters in the formula. One is the Sacral Slope, and the other is the Pelvic Tilt. The Sacral Slope could be described as sacral tilt and Pelvic Tilt as pelvic rotation. Both values ​​are also given in ° degrees and are basin-related positional parameters (see Fig. 3). The Pelvic Tilt Angle is formed as follows: We need 2 lines. A vertical line through the center of the hip joint and a line from the center of the hip joint to the center of the base of the sacrum. To determine the Sacral Slope, we also need 2 lines. A straight line sits directly on the base of the sacrum. The other line runs horizontally from the most anterior point of the sacrum to the floor.7 Figure 3 shows pelvic incidence, pelvic tilt, and sacral slope.

hollow back is an increased lumbar lordosis
Fig. 3: PI, Pelvic incidence; PT, Pelvic tilt; SS, Sacral slope

For guidance, Boulay et al. (2006) examined 149 adults with no spine-related medical history and came up with the following mean values:15

Pelvic incidence

  • Women: 56° ± 10
  • Men: 53° ± 10,6

Sacral Slope

  • Women: 43,2° ± 8,4
  • Men: 41° ± 8,5

Pelvic Tilt

  • Women: 13,6° ± 6
  • Men: 13° ± 6

It is likely that the greater the pelvic incidence, the greater the lumbar lordosis. The positional parameters Sacral Slope and Pelvic Tilt, but also parameters related to the spine, such as lumbar lordosis and kyphosis in the thoracic spine area, can probably be influenced by posture, muscle tone, and statics of the lower extremities.7 Core training can be useful to reduce pain in the lower back or reduce the likelihood of experiencing pain.16 If you have a hollow back posture, it would probably be a good idea to train your core appropriately…unless there is a medical indication otherwise.

There’s more information on my YouTube channel (in German) and Instagram profile (English)! And especially on YouTube, you will find cool exercises for your core. 🙂


  1. American College of Sports Medicine. Clinical Exercise Physiology. (Lippincott Williams & Wilkins, 2019).
  2. Norasteh, A., Hajihosseini, E., Emami, S. & Mahmoudi, H. Assessing Thoracic and Lumbar Spinal Curvature Norm: A Systematic Review. Physical Treatments: Specific Physical Therapy Journal 183–192 (2019) doi:10.32598/ptj.9.4.183.
  3. Willardson, J. M. Developing the core. (Human Kinetics, 2014).
  4. National Academy of Sports Medicine. NASM essentials of personal fitness training. (Jones and Bartlett Publishers, Inc, 2017).
  5. Dimitrijević, V., Šćepanović, T., Milankov, V., Milankov, M. & Drid, P. Effects of Corrective Exercises on Lumbar Lordotic Angle Correction: A Systematic Review and Meta-Analysis. International Journal of Environmental Research and Public Health vol. 19 Preprint at https://doi.org/10.3390/ijerph19084906 (2022).
  6. Furlanetto, T. S., Sedrez, J. A., Candotti, C. T. & Loss, J. F. Reference values for Cobb angles when evaluating the spine in the sagittal plane: A systematic review with meta-analysis. Motricidade vol. 14 115–128 Preprint at https://doi.org/10.6063/motricidade.10890 (2018).
  7. Ferraris, L., Koller, H., Meier, O. & Hempfing, A. Die Bedeutung der sagittalen Balance in der Wirbelsäulenchirurgie. Dtsch. Ärzte-Verlag 1, 502–508 (2012).
  8. le Huec, J. C., Aunoble, S., Philippe, L. & Nicolas, P. Pelvic parameters: origin and significance. European Spine Journal 20, 564–571 (2011).
  9. Laouissat, F., Sebaaly, A., Gehrchen, M. & Roussouly, P. Classification of normal sagittal spine alignment: refounding the Roussouly classification. European Spine Journal 27, 2002–2011 (2018).
  10. Clark, M. A. & Lucett, S. C. NASM’s Essentials of Corrective Exercise Training. (Lippincott Williams & Wilkins, 2011).
  11. Furlanetto, T. S., Sedrez, J. A., Candotti, C. T. & Loss, J. F. Reference values for Cobb angles when evaluating the spine in the sagittal plane: A systematic review with meta-analysis. Motricidade vol. 14 115–128 Preprint at https://doi.org/10.6063/motricidade.10890 (2018).
  12. Geiger, E. v., Müller, O., Niemeyer, T. & Kluba, T. Adjustment of pelvispinal parameters preserves the constant gravity line position. Int Orthop 31, 253–258 (2007).
  13. Abelin-Genevois, K. Sagittal balance of the spine. Orthopaedics and Traumatology: Surgery and Research vol. 107 Preprint at https://doi.org/10.1016/j.otsr.2020.102769 (2021).
  14. von Haaren, F. F. W. & Friedrich-Wilhelm, F. Bestimmung der spinopelvinen Parameter bei Patienten mit Fragilitätsfrakturen des Beckenrings. (2019).
  15. Boulay, C. et al. Sagittal alignment of spine and pelvis regulated by pelvic incidence: Standard values and prediction of lordosis. European Spine Journal 15, 415–422 (2006).
  16. Chang, W.-D., Lin, H.-Y. & Lai, P.-T. Core strength training for patients with chronic low back pain. J Phys Ther Sci 27, 619–622 (2015).



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