For individuals starting resistance training with the goal of increasing muscle mass, the question of whether a single weekly workout is sufficient is common. While any resistance stimulus is generally better than none for overall health, the biological and mechanical requirements for building muscle, a process known as hypertrophy, are highly demanding. Achieving optimal muscle growth requires a strategic balance between exercise frequency, the magnitude of the work performed, and consistent support from outside factors like nutrition and recovery.
The Biological Timeline of Muscle Protein Synthesis
Muscle growth is fundamentally driven by Muscle Protein Synthesis (MPS), which is the physiological process of creating new muscle proteins to repair and build tissue. A single session of resistance exercise acts as a trigger, sharply increasing the rate of MPS in the worked muscles. Research indicates that following a strenuous workout, MPS typically peaks around 24 hours post-exercise, returning to near baseline levels within 48 hours. A once-per-week schedule leaves five days where the primary growth signal is absent. To maximize muscle building over time, the goal is to repeatedly stimulate this MPS response before the previous stimulus completely fades, keeping the rate of synthesis elevated for more days out of the week.
The Role of Volume and Intensity in a Single Weekly Session
Since the MPS window is short-lived, a single weekly workout must compensate for the lack of frequency by maximizing the total work performed. This is achieved through manipulating training volume (total sets and repetitions) and intensity (the load lifted). Optimal weekly volume for hypertrophy often involves 10 or more hard sets per muscle group, requiring a single session to condense an immense amount of work. Attempting this high volume and intensity in one long session creates a significant practical challenge and raises the risk of overtraining or injury. For most individuals, spreading the total weekly volume over two or three sessions allows for higher quality work and a more sustainable application of the necessary stimulus.
The Detrimental Effects of Extended Recovery Periods
The primary limitation of a once-a-week schedule is the extended recovery period, which spans six days. After the MPS rate returns to baseline within 48 hours, the body is no longer in an accelerated building state. For muscle hypertrophy, the body must maintain a positive net protein balance, meaning protein synthesis must consistently exceed protein breakdown. While once-a-week training can be effective for maintaining existing muscle mass, the six-day gap allows too much time for the anabolic signal to dissipate when actively building new muscle. Training a muscle group at least twice a week is recommended to ensure the tissue constantly receives a growth signal before the effects of the previous one disappear.
Non-Training Factors Critical for Muscle Maintenance
When training frequency is low, factors outside the gym become more important in ensuring any potential gains are supported. Nutrition, specifically adequate protein intake, provides the necessary building blocks for the MPS process. Individuals aiming for muscle growth should target a daily protein intake between 1.2 and 2.0 grams per kilogram of body weight, consistently met throughout the week. Sleep and hormonal regulation also play a major part in recovery and growth. Insufficient sleep, typically less than seven to nine hours, can elevate cortisol and reduce testosterone, creating a hormonal environment that favors muscle breakdown over muscle synthesis.