It would be great if the hard work you put in at the gym today would result in visible changes tomorrow. While changes at the cellular level are set in motion immediately after your workout, you won't see significant changes in muscle size for several weeks. However, exercise-induced inflammation may temporarily make you look a little larger.
Overload and Muscle Response
Muscle growth is initiated by overload, a fundamental principle of exercise that states that when muscles are subjected to challenging work beyond what they are accustomed to, adaptations will occur to make them stronger. One hard workout will stimulate the overload response, but if you don't consistently challenge the muscles over a duration of time, changes will be minimal and short-lived. Without perpetual stimulus, your muscles will quickly revert back to their pre-exercise state.
Adaptations from overload begin to take place immediately following a bout of exercise when traumatized muscle fibers go on the defensive, invoking an immune response. Like any soft tissue injury, exercise-induced muscle trauma leads to inflammation, which serves to contain and repair the damage, and to clear away debris from damaged muscle cells. According to exercise scientist Len Kravitz, PhD, the inflammatory response is due to inflammatory cytokines, healing proteins that rush to the site of injury to initiate the repair process. At the same time, hormone-like substances called prostaglandins are released to control inflammation. Post-exercise inflammation can persist for three days or longer, usually accompanied by muscle soreness.
Muscle is the most adaptable tissue in the human body, and is highly responsive to resistance exercise. Muscle growth is due to an increase in cross-sectional area of individual muscle fibers. The chain of events set in motion after a bout of resistance exercise is a complex process involving numerous hormones, cellular organelles and growth factors. When the rate of muscle synthesis exceeds the rate of muscle fiber breakdown, growth occurs. Genetics has a profound influence on how much growth can naturally occur in your muscles.The amount and type of muscle fibers you inherited is a key factor. Men have a greater capacity than women for muscle growth due to higher testosterone levels.
Long-Term Muscle Growth
Growing muscle is a long and drawn-out process. Consistently subjecting the muscles to trauma and then resting to allow them to heal will eventually yield increases in muscle strength and size. Frequency of exercise, weight load and recovery are all important components of a successful muscle-building program. A 2011 study published in the "Journal of Sports Medicine and Physical Fitness" found that lifting weights at a volume of 80 percent of six-rep max for three sets, with two minutes rest between sets, resulted in a high testosterone stimulus for muscle growth. Six-rep max is the most weight you can lift six times, but not seven, with good form. For example, if you can do six biceps curls using 30-pound dumbbells, then begin lifting with 80 percent of 30. Since dumbbells come in 5-pound increments, perform three sets to fatigue with 25-pound dumbbells.