During your first session at The Perfect Workout, you may have asked your trainer the following question: “How much muscle (or strength) should I expect to gain during my first few weeks?”
Based on your trainer’s experience, he or she may have offered an educated guess. However, the truth is we have no idea how much strength or muscle you, as an individual, will gain during your first few weeks. No one does. There is just too much variability between separate people. Sure, we can offer averages based on previous results, but results vary and outliers do exist.
This point is illustrated well by a 2005 study that involved 9 schools across the US and one in Dublin, Ireland . This large study showed that you’re almost guaranteed to gain strength and muscle from a proper strength training program, but as far as how much you’ll improve is very hard to predict. The study’s researchers followed 585 men and women, 18 to 40 years old, for 12 weeks of upper arm training. The collaboration of 10 schools enabled a large sample size of participants, and this is important because large sample sizes provide better representations of the universal response.
The training featured four exercises, two for the biceps and two for the triceps. Each exercise was performed for three sets to the fatigue point of “muscle success” and the weight loads were increased throughout the training. Before and after the 12 weeks, one-repetition maximum tests and MRIs were conducted to measure arm strength and muscle size.
The researchers predicted a wide range of muscle and strength changes…and they were correct. Women and men ranged from 0 to 250% and 0 to 150% stronger, respectively. Average strength gains were 64% and 40%. Muscle size changes ranged from –3% to 56% and –2% to 59% in women and men. Average muscle size changes were 18% and 20%.
As mentioned, there were outliers. Outliers, in research terms, are considered two standard deviations away from the mean and usually make up less than 5% of any sample. In terms of strength, since no participants lost strength, outliers basically didn’t exist on the low end. On the high end, 2% of women and 3% of men were outliers. In terms of increasing muscle tissue, thirty-six people gained less than 5% and 10 people gained more than 40%.
The previously mentioned ranges included everyone in the study. Ignoring the outliers and near-outliers, participants mostly gained from 5% to 30% more muscle and also gained between 5% and 95% in strength.
The researchers listed gender, age, current physical activity level, previous training, and hormone status as as some of the factors affecting how much people will gain from strength training. The researchers did not allow people who had been weight training during the previous year to participate in the study. Hormone levels, such as testosterone, were not tested. The correlation between age and muscle size was extremely weak, so age did not predict muscle growth in this study. And physical activity outside of the study’s training was not recommended.
That leaves us with gender. While gender could explain the disparities in average strength and muscle mass gained in women versus men, it obviously doesn’t explain differences within each gender. For example, one woman gained no strength whereas another became 250% stronger. Apparently even more additional factors than the researchers listed (such as the amount of muscle fibers a person is born with, muscle fiber type ratio, length of the muscle bellies and tendons, etc.) allow some people’s bodies to better respond to strength training (and some people’s bodies have less responsiveness).
There are two observations I’ll make regarding this study. First, the trainees were given strict orders to make no dietary changes. If allowed to consume more protein in their diets (especially immediately following workouts for better post workout recovery) it’s likely that the improvements would’ve been higher across the board. Second, there are ranges for strength and muscle mass that include the vast majority, but predicting the right numbers for a specific individual’s muscle and strength gains is unlikely. A more constructive approach is to observe the gains made in the initial sessions and then perpetually work to improve those values.
By Matt Hedman, President of The Perfect Workout
- Hubal, M. J. (2005). Variability in muscle size and strength gain after unilateral resistance training. Medicine, Science, Sports & Exercise, 37(6), 964-72.