Tired back muscles can be sore and painful for a time due to the chemical processes which occur from being overworked. Muscles can also feel tired from minor tissue damage, especially during the healing phase.
Tired muscles should not be a chronic condition, but can certainly result from overuse or repetitive strain conditions. Typically, tired muscles in the back and neck will feel better within 24 to 48 hours, once rested. Longer symptomatic expressions may be indicative of something far more sinister than simple overexertion at work in the muscular anatomy.
Of course, if there is an obvious reason for recurrent tiredness, such as regular resistance training or physical labor, then there may be nothing to be concerned about at all.
The back muscles are designed for virtuously continuous work. Just keeping your torso upright, while sitting or standing, takes tremendous effort from all your postural muscles. However, doing intensive and heavy labor can wear out the muscles in the neck, back or buttocks.
Tired muscles will feel sore to the touch and will also likely hurt when moved. This is generally due to a combination of lactic acid buildup in the muscles themselves and the possibility of small rips and tears due to muscular injury. The latter reason for pain is commonly known as back muscle strain.
Some complementary therapists believe the fascia to be involved with many of these pain syndromes, which is quite possible, as is the inclusion of ligaments and/or tendons.
Typically, there is no treatment required for sore muscles due to overuse. Simply give the area a rest for a couple of days and you should be fine. If the symptoms are moderate to severe, consider OTC pain relievers or apply heat or ice as pain management techniques.
Tiny muscle tears should heal without complication, but larger scale injuries may require an extended rest period or even professional rehabilitation. If symptoms persist past 72 hours, consider contacting your physician for detailed information about how to proceed with care.
Personally, I always find a good swim does wonders, since it gently metabolizes the chemical waste products while not putting any pressure on small muscular injuries.
Lactic acid is the usual culprit for muscular soreness, since it is a metabolic waste product which remains trapped in muscles when they are used excessively.
Bed rest is not good for overuse conditions, but instead, gentle movement and normal activity are recommended, since this motion will help facilitate metabolism of the irritating chemicals.
Remember that continual overuse may lead to injury or even repetitive stress back pain conditions which may become chronic. While these instances are rare, they do occur in some unfortunate patients, so treat your body well and do not overdo it too much or too often.