According to certified personal trainer Paige Waehner for About.com, an effective strength-training program is based on a planned, consistent approach that utilizes various weight-bearing maneuvers intended to break down muscle tissue and subsequently repair it with restorative sleep and a diet containing plenty of lean proteins. Strength increases as exercises are continuously modified to challenge muscle groups past their current training limits.
Waehner explains that muscles contain their own type of memory. Depending on the regularity and intensity of a workout regimen, muscles generally require a change every four to six weeks to avoid plateauing. They are designed to adapt to increasing demands only as much as is required of them. Once muscles learn to perform a repetitive movement at a set weight limit and position, they begin to expend less energy to complete the same action. This causes the muscles to retain their size without any growth. Strength only improves as higher demands are placed on the body to force muscle groups to sustain their enlargement through the creation of new tissue. If muscles are not used, they begin to deteriorate.
Waehner recommends meeting with a personal trainer to discuss strength-training goals and work on a tailored exercise schedule designed to meet those goals. It is also important to remain safe and methodical to avoid over-exertion or injury to the muscles by pushing them too far.