As fitness has surged in popularity, more and more women are adding weight training to their routines. This is a game changer since weights can improve lean muscle mass, aid with weight loss, lower inflammation, improve brain function, and build bone, lowering osteoporosis risk.
Despite the increase in weight training as a go-to exercise mode, many women are still selling themselves short, either by lifting weights that are too light, or making other mistakes with their programming. Unfortunately, there is a powerful cultural message that women should only train with light weights, often doing bizarre exercises that lead to poor returns when compared to more traditional exercises. Not only do the most popular women’s fitness magazines never show women lifting heavy, these fitness models aren’t even training with weights that are heavy enough to produce changes in body composition or strength.
Now you might argue that no one gets their advice from mainstream fitness magazines. However, studies of how women actually train show that the message of how to design workouts properly is not getting through. For example, surveys show that women tend to self-select weights that are too light to produce any body composition or strength benefits. One study found that even women with training experience pick weights that are 30 percent lower than the lightest weight needed to produce an increase in muscle.
Therefore, this article will provide evidence showing that women will benefit from putting a few more plates on the bar to get the most out of their efforts.
How Program Design Theory Works
Traditionally, scientists believed that heavy loads trained for fewer reps (weights above 80 percent of maximal for 1-6 reps) will build strength, while having a lesser impact on muscle growth. Moderate loads for moderate reps (weights between 60 and 80 percent of maximal for 8-15 reps) were believed to stimulate the greatest increases in muscle growth. Finally, lighter loads trained for higher reps (weights below 60 percent of maximal for 20-plus reps) were used for muscle endurance and were not thought to impact muscle growth.
More recently, studies done almost exclusively on men have shown that light load, high rep training can build muscle just as effectively as heavier training as long as the light load condition is performed to failure. Researchers explain this effect by citing the Size Principle of motor unit recruitment. This theory was based on our understanding that muscles are made up of muscle fibers, which are recruited in an orderly fashion from lower threshold weaker fibers all the way up to the highest threshold strongest fibers.
When lifting heavier loads, the vast majority of muscle fibers are recruited from the beginning of the set whereas with lighter loads, only the lower threshold fibers are recruited. However, with low load training to failure, it’s possible to train those higher threshold muscle fibers.
For example, in a set of 30 reps to failure, as lower threshold fibers become fatigued, higher threshold fibers are recruited, and they too end up getting fatigued and are unable to continue to produce force as failure approaches. By the time you reach the final reps of a high-rep, low-load set, just as many fibers should be trained as with a heavy, low rep set.
A 2017 meta-analysis supports this idea that heavy and light loads can be equally effective in promoting muscle growth provided training is carried out with a high level of effort. However, the vast majority of the studies used in this analysis were performed on male subjects. By taking a look at the studies that included women, a completely different picture plays out.
Out of 8 studies that included women, 5 showed that heavy training resulted in greater strength than light load training. In the only study that tested the effect of loads on muscle growth, the women lifting with heavier weights (6-10 RM) gained significantly more muscle than those training with lighter loads (20-30 RM).
This study was interesting because in addition to determining how loads affected muscle growth it looked at the impact of lifting speed. Researchers recruited 34 healthy untrained women with an average age of 21 and put them into one of four experimental groups:
1) Control group
2) Traditional Strength: A high load group (80-85 percent of the 1RM for 6-10 reps)
3) Endurance: A low load group (40-60 percent of the 1 RM for 20-30 reps), and
4) Slow Speed: A high load/slow group (80-85 percent of the 1 RM for 6-10 reps, using a lifting tempo of 10 seconds concentric and 4 seconds eccentric). The tempo for the other two groups was 1-2 seconds for both phases of the lift.
Workouts were 2 days a week for the first week and 3 after that for a total of 6 weeks. Exercises were leg press, squat, knee extension.
Results showed that the Traditional Strength (80-85 percent) group increased muscle by 0.7 kg, decreased fat mass by 0.3 kg, and had a 3 percent decrease in body fat. This group also was the only one to increase the size of both slow and fast-twitch muscle fibers, with a significant increase in the slow-twitch Type I, the fatigue resistant Type IIA fibers, and the powerful Type IIX fibers.
In the Endurance (40-60 percent, normal speed) group, there was a 0.1 kg increase in muscle mass, 0.2 kg increase in fat mass, and 0.4 percent increase in body fat percentage. This group had no significant increase in the size of any muscle fibers.
In the Slow Speed group (80-85 percent, 10 second concentric, 4 second eccentric), there was no change in any body composition markers. This group increased cross-sectional fiber area in the two fast-twitch fibers tested, Type IIA and IIX but had no increase in the Type I fibers.
Of particular interest was how the different training parameters impacted the Type IIA fibers that are both very powerful and fatigue resistant because they have the greatest functional benefit for athletes and people in the general population. Among the two heavy loading groups, both the slow and normal speed groups increased the Type IIA fibers, with the Traditional Strength group increasing fiber size by 38.8 percent whereas the Slow Speed group increased by 10.6 percent.
The research group writes that this study confirms the generally accepted view that training load has the most significant impact on strength and hypertrophy (the formal term for muscle building). In contrast to studies performed on men that have shown similar hypertrophy responses to low and high load training, this study showed that unlike the high load Traditional Strength protocol, the low load Endurance protocol produced no increase in muscle cross sectional area or changes in body composition.
The take away is twofold:
1) Women should not rely on research done on men to tell them how to train, and
2) Women need to lift heavy loads if they want to get the most out of their efforts.
Number one might seem obvious, but the reality is that there is an extreme gender bias in exercise physiology research that is only beginning to get rectified with more scientists doing studies on women. Historically, sex differences were ignored, and women were viewed as “small men,” getting the same training and nutrition advice, despite the fact that recent research shows considerable differences in metabolism, muscle function, and recovery. For example, women rely more on fat to fuel exercise, while men use more glucose—a difference with implications for both workout and recovery nutrition.
Even now that more and more research is being done on female subjects, sex differences are often attributed to the fact that women have higher estrogen levels despite a lack of conclusive research demonstrating this. The bottom line is that if you’re a woman who is committed to getting results, or a coach with female athletes who are serious about their training, it’s worth it to seek out research and advice based on female physiology and metabolism. Be skeptical of advice based on research performed on men, especially when it comes to metabolism and muscle function.
Regarding #2, the typical excuses for training only with light weights are no longer acceptable. It’s time for women to get on board with heavy load training, incorporating it into a properly designed, periodized program.
“Periodization” refers to when you design your workouts in phases that allow you to focus on one goal for a few weeks and then switch to another goal once your body adapts. Each phase typically lasts 3 to 6 weeks. Novices should use longer phases closer to 6 weeks, whereas advanced trainees should switch their program up every 3 weeks. A basic way to periodize workouts is to alternate between the following:
“Accumulation” phases in which you focus on increasing muscle with more volume, moderate weights, and higher reps, and
“Intensification” phases in which you focus more on building strength with less volume, heavier weights, and lower reps.
Here’s how it works:
For the first phase in which you train accumulation, use 4 to 5 sets per exercise and 8 to 12 reps to focus on increasing muscle mass. When we say 8 to 12 reps, this means that you should be reaching failure within that rep zone. If you like percentages, 8 reps would equal a load that is 80 percent of the maximal amount you can lift one time (known as your 1RM) whereas 12 reps equals 70 percent of your 1RM.
For the second phase in which you train intensification, increase your weights and lower your reps so that you can do 3 to 8 reps with most of your reps in the 5-7 range before reaching failure. You could even include some maximal load training in which you do 1 or 2 reps per set, however, this technique is best used by advanced trainees. Intensification will target the higher threshold motor units in the muscle to ensure that you are training all of your beautiful muscle. By the end of this training cycle, you should be able to increase your weights once you go back to accumulation.
Most of your exercises should be multi-joint movements that recruit a lot of muscle mass at once. Squats, presses, rows, pull-downs (or pull-ups), step-ups, lunges, and deadlifts are examples of exercises to design your workout around. Include a few isolation exercises to round things out and ensure you hit all muscle groups and avoid imbalances in the body.
Final Words: There’s no drawback to incorporating heavy lifting into your training: You will get better body composition and strength results, while igniting your motivational fire to continually challenge yourself to put more weight on the bar.