How many hours do you spend lying on the beach? Experts advise against exceeding this limit (and it's not because of melanoma).

There are few sensations as pleasurable as lying on the sand at the beach on the first day of vacation . And when we say beach, we mean the lawn by the apartment pool, or even a sun lounger or hammock. A true pleasure that's probably overrated and amplified by the fact that we've put aside our professional obligations, early mornings, or rushing from one place to another for a few days.

However, enjoying a (as they say) well-deserved break by letting yourself go on the sand has a fine print that we often overlook. It's about the possible side effects that can occur after spending several hours lying on the beach .

The possibility of muscle soreness appearing after a few hours, or even of these pains sabotaging the rest of your vacation, is reason enough to take appropriate measures to minimize the risk of this happening.

And "lying on the sand for a long time could lead to the development of stiffness or muscle contracture in the back ," warn experts from the Kovacs Back Unit at HLA Moncloa University Hospital.

Basically, this happens because sand is an uneven and relatively hard surface that doesn't adapt well to the curvatures of the spine (thoracic kyphosis and cervical and lumbar lordosis). However, " a healthy back should allow you to lie on the sand for a while without pain or other harmful consequences."

Maximum, 48 hours

Since we can't change the terrain conditions (unevenness and rigidity), we'll focus on the factors we can modify, including the amount of time we spend lying down.

In general, lying on any surface for more than 48 hours at a time is harmful, because physical inactivity reduces blood flow and worsens muscle tone and coordination.

However, in this matter, experts emphasize that the time that one can remain lying on the sand without feeling stiffness or pain when maintaining that position or getting up, depends on individual factors , such as the degree of curvature of the spine , its degree of wear (which is influenced by age) and the state of the muscles, as well as the posture in which one is.

Light and frequent changes

Most people can last longer on the sand if they lie on their backs, resting their neck on a pillow, and with their knees bent.

Furthermore, "if they slightly modify their posture from time to time, for example, by slightly rotating their hips and changing the position of their legs, they will alternate the area that receives the most pressure and will likely be able to hold their posture for longer periods of time without pain," note the experts at the Kovacs Back Unit.

Lying on any surface for more than 48 hours at a time is harmful.

Now, the most important thing to avoid back pain is prevention , which involves adopting healthy habits such as exercising regularly. The better developed and coordinated the muscles are, the better the spine will support any posture or activity.

On your back, stomach, or side, which is better?

To some extent, the best posture varies for each person, as it depends on the shape of their spine, which varies from case to case. However, in general, on a rigid surface like sand, lying in the fetal position can easily cause uncomfortable pressure on the outer part of the hip and the trochanter (the upper end of the femur). This pressure is less pronounced if, instead of lying perfectly sideways, you are lying "three-quarters" with your lower leg straight and the other bent with your knee resting on the sand. In both cases, experts recommend using a pillow or your arm to try to align your neck with the axis of your spine.

On the other hand, to be able to breathe while lying face down, you need to hyperextend or twist your neck, which over time can cause a certain degree of neck and back tension. Therefore, lying face up is often the preferred position on this type of surface.

Additionally, bending your knees can correct the curvature of your lower back, increasing the support surface and improving pressure distribution. To complete this ideal posture, use a pillow or rolled-up towel to align your neck with the axis of your spine.

Pillow, yes or no?

Although experts welcome the use of a pillow or a rolled-up towel as a cushion , they also remind us that the shape and curvature of the spine is not exactly the same for every person.

In any case, the idea is to keep the neck in the same axis as the spine. Without a pillow or equivalent , it tends to be hyperextended, and with a pillow that's too thick, it tends to be hyperflexed.