Running: Temporary Height Reduction, Spinal Health, and Benefits

Why does running make you shorter?

Running does not permanently make you shorter. While intense activity, including running, can lead to a temporary, minor reduction in height due to spinal disc compression, this effect is entirely reversible and part of normal daily physiological fluctuations.

The Core Misconception vs. Reality

The idea that running makes you shorter is a common misconception, often stemming from a misunderstanding of spinal mechanics and the temporary nature of physiological changes. In reality, running is a weight-bearing exercise that, when performed correctly, generally contributes to stronger bones and a healthier spine, rather than causing permanent height loss. The perceived "shortening" is a transient phenomenon.

Understanding Spinal Compression During Running

Your spine is a sophisticated structure designed to support your body, allow movement, and protect your spinal cord. It consists of vertebrae separated by intervertebral discs. These discs are crucial to understanding temporary height changes:

• Intervertebral Discs: These jelly-filled shock absorbers are primarily composed of water (around 80%) and act as cushions between your vertebrae. They allow for spinal flexibility and distribute forces.
• Gravity and Impact: Throughout the day, and especially during weight-bearing activities like running, gravity and the impact forces of each step compress these discs. Each time your foot strikes the ground, a force travels up your kinetic chain to your spine.
• Fluid Loss: This compression causes the discs to gradually lose some of their fluid content, much like squeezing a sponge. This temporary loss of fluid results in a slight reduction in disc height, which in turn leads to a very minor, temporary decrease in overall spinal length and thus, your height.
• Magnitude of Compression: The actual amount of height lost is typically very small, often just a few millimeters, and varies based on individual factors, running intensity, and duration.

The Role of Connective Tissues

While intervertebral discs are the primary contributors to temporary height changes, other connective tissues also experience transient compression:

• Articular Cartilage: The smooth cartilage covering the ends of bones within joints (like knees, hips, and ankles) also compresses slightly under load. While this contributes minimally to overall height changes, it's another example of how the body's shock-absorbing tissues temporarily deform under stress.
• Ligaments and Tendons: These structures primarily provide stability and transmit forces, but they do not contribute to height reduction in the same way as fluid-filled discs.

Is This Compression Permanent or Harmful?

It is crucial to understand that this spinal compression is a normal, healthy, and entirely reversible process:

• Rehydration and Recovery: When you rest, particularly during sleep, the pressure on your discs is relieved. They then reabsorb fluid, rehydrating and expanding back to their original height. This is why most people are slightly taller in the morning than they are in the evening.
• Benefits of Running: Far from being harmful, the controlled loading experienced by the spine during running can actually be beneficial. It stimulates bone remodeling, which can lead to increased bone density over time, strengthening the vertebrae. Additionally, running strengthens the core muscles that support the spine, further promoting spinal health.
• Spinal Health: When performed with good form and appropriate progression, running generally promotes, rather than harms, spinal health. It encourages blood flow and nutrient exchange within the discs, which is vital for their long-term health.

Factors Influencing Perceived Height Changes

Several factors can influence how a person perceives height changes, some of which are often mistakenly attributed to running:

• Time of Day: As mentioned, everyone experiences natural daily height fluctuations dueishing to spinal compression and rehydration. This is a normal physiological rhythm, irrespective of running.
• Posture: Running, especially when combined with core strengthening exercises, can significantly improve posture. By strengthening the muscles that support an upright spine, running can actually make individuals appear taller by correcting slouching or poor alignment.
• Age-Related Height Loss: Over many decades, natural aging processes can lead to a gradual loss of height due to disc degeneration, vertebral compression fractures (in cases of osteoporosis), and changes in spinal curvature. This is a long-term, irreversible process distinct from the temporary effects of running.

Mitigating Temporary Compression and Supporting Spinal Health

While temporary compression is normal, optimizing your running practice can further support spinal health:

• Proper Running Form: Maintain an upright posture, avoiding excessive slouching or arching. Keep your head up, shoulders relaxed, and gaze forward. A slight forward lean from the ankles is ideal, not from the waist.
• Core Strength: A strong core (abdominal and back muscles) acts as a natural corset, providing essential support and stability for your spine. Incorporate exercises like planks, bird-dogs, and glute bridges into your routine.
• Hydration: Staying well-hydrated ensures your intervertebral discs have ample fluid to maintain their structure and shock-absorbing capabilities.
• Recovery and Sleep: Allow your body adequate time to recover after runs. Quality sleep is when your discs have the best opportunity to fully rehydrate and restore their height.
• Cross-Training and Stretching: Incorporate activities that promote spinal mobility and flexibility, such as yoga or Pilates. Regular stretching can help maintain good posture and alleviate muscle imbalances.

Conclusion: Running's Overall Impact on Your Body

The notion that running makes you permanently shorter is a myth. While a minor, temporary reduction in height due to spinal disc compression is a normal physiological response to weight-bearing activity, this effect is fully reversible with rest and hydration. Running, when approached intelligently and with proper form, is a profoundly beneficial exercise that supports bone density, strengthens core musculature, and contributes to overall musculoskeletal health, including a healthy and resilient spine. Focus on the myriad positive impacts running has on your body, rather than a transient few millimeters.