Why on the second day after training the muscles hurt more than on the first

This common occurrence is known as delayed or delayed muscle pain. It occurs after a really hard workout, when the load exceeds the usual by more than 10%, and in the exercises the emphasis is on the eccentric phase (the part of the movement when the muscles are stretched under load, for example: lowering the bar in the bench press or the barbell to the floor in the deadlift) …

Such training provokes extensive microdamage of muscle fibers and the development of the inflammatory process.

What happens in the body after exercise

On the first day, in response to micro-damage to muscle fibers, the body releases cytokines, hormone-like proteins that regulate the body's immune response and inflammatory response.

Leukocytes are directed to the torn muscle fibers, which cleanse the damaged tissue and accelerate regeneration. Also, at the site of inflammation, a large amount of prostaglandins are released - active substances that dilate blood vessels, create a feeling of warmth in the damaged area and increase the sensitivity of pain receptors.

However, inflammation is gradual and does not peak until 24–48 hours after exercise. At this time, the regeneration process is in full swing, and the pain sensations intensify.

Lactic acid has nothing to do with it

It used to be thought that lactic acid was to blame for post-workout pain. However, it was later proved that this opinion was wrong.

Lactic acid affects muscles during training: it is she who makes you feel a burning sensation at the end of a difficult set. However, as soon as you stop making efforts, the blood begins to flush lactic acid from the muscles.

Scientists have shown that blood lactic acid levels peak 3–8 minutes after maximum effort and drop to pre-workout levels within 60 minutes. And because lactic acid is released from the muscles so quickly, it has no effect on pain 1-2 days after exercise.

How to relieve pain after exercise

A 2003 study showed Delayed onset muscle soreness: treatment strategies and performance factors that the following are most effective for relieving delayed muscle soreness:

Taking non-steroidal anti-inflammatory drugs.
Massage (effectiveness depends on technique).
Moderate physical activity.

The latter is recognized as the most effective remedy. Do a good warm-up and repeat the workout at 50% of your working weight. If you are not going to the gym, you can simply ride a bike or take a walk: physical activity will warm up the muscles and reduce pain.

The same study showed that ultrasound, homeopathy, and stretching had no effect on post-workout muscle soreness.

If you want to relieve muscle stiffness, try myofascial relaxation on massage rollers instead of stretching. Such self-massage will help warm up the muscles and, at least temporarily, reduce pain.