Can Gym Class Alone Improve Bone Density in Females?
As a certified strength and conditioning coach, I constantly preach the importance of daily physical activity for kids. New studies are always highlighting the benefits, especially for young girls and their long-term health. But is 60 minutes of gym class per week really enough to improve bone density in females? The short answer is no.
And that single word has huge implications for lifelong health.
Disclaimer: This article is for informational purposes only and is not meant to treat or diagnose any condition. It is recommended that you speak with your doctor before starting any exercise program, changing your daily nutrition, or adding any supplements to your regimen.
Key Takeaways
- A seven-year study found that 60 minutes of weekly gym class is not enough to significantly improve bone density in girls.
- The study showed that increasing gym time to 200 minutes per week led to measurable improvements in bone thickness, strength, and density for girls.
- Weight-bearing exercises like gymnastics, basketball, soccer, and tennis are particularly effective for building strong bones during adolescence.
- Proper nutrition, especially adequate intake of calcium and vitamin D, is critical for maximizing bone health alongside exercise.
How Can You Improve Bone Density in Females?
To really understand what it takes to improve bone density, we need to look at the science. A significant seven-year study published in the journal Calcified Tissue International provides some clear answers. Researchers took a close look at students from four different schools in Sweden to see how much gym class it took to make a real difference.
One group of 170 students (including 72 girls) was given 200 minutes of physical education each week. Another group of 91 students (with 44 girls) received the standard 60 minutes per week. All the schools were in the same geographic area with similar socioeconomic backgrounds to ensure a fair comparison.
The results were fascinating and pointed to a clear gender-based difference. The girls who received 200 minutes of gym class showed significant improvements in their bone density. The boys, however, did not see a similar boost.
Researchers believe this happened because the boys in the study were already more active outside of school, getting about three hours of weight-bearing activity each week on their own time. The girls were generally less active, so the structured exercise at school made a much bigger impact.
The Specific Bone-Building Benefits
The numbers don’t lie. For the girls in the 200-minute group, the study found a 2.5% greater cortical thickness, which is the dense outer layer of the bone. They also showed a 6.9% greater polar stress-strain index, a key measure of bone strength, along with a higher overall bone mineral density.
This tells us that to improve bone density effectively, young women need consistent, high-impact activities. These are exercises where you move against gravity while on your feet. According to the International Osteoporosis Foundation, physically active young girls gain about 40% more bone mass than the least active girls.
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Some of the most effective weight-bearing exercises mentioned in the study include:
- Basketball
- Tennis
- Soccer
- Gymnastics
As Dr. Jesper Fritz, one of the study’s authors, noted, optimizing bone mass in youth has a lasting positive impact on preventing fractures in adulthood. This is why I always tell my clients that what you do in your teens sets the foundation for the rest of your life.
Beyond the Gym: The Role of Nutrition
While 200 minutes of weekly exercise is a great target, it’s only half of the equation to improve bone density. As a sports nutritionist, I can’t stress this enough: you can’t out-train a poor diet. Strong bones require the right building blocks.
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The two most critical nutrients are calcium and vitamin D. Calcium is the mineral that makes bones hard, and vitamin D is necessary for your body to absorb that calcium effectively. Many young women, unfortunately, don’t get enough of either.
Here’s a quick guide to daily calcium and vitamin D needs for teenage girls:
| Nutrient | Recommended Daily Intake (Ages 9-18) | Good Food Sources |
| Calcium | 1,300 mg | Dairy products (milk, yogurt, cheese), fortified cereals, leafy greens (kale, broccoli), tofu |
| Vitamin D | 600 IU (15 mcg) | Fatty fish (salmon, mackerel), fortified milk, egg yolks, sunlight exposure |
Protein is also essential for creating the collagen framework of your bones. According to the Gatorade Sports Science Institute, adequate protein intake supports anabolic pathways that are crucial for bone health, especially for female athletes.
Source:
Jesper Fritz, Rachel L. Duckham, Timo Rantalainen, Björn E. Rosengren, Magnus K. Karlsson, Robin M. Daly. Influence of a School-based Physical Activity Intervention on Cortical Bone Mass Distribution: A 7-year Intervention Study. Calcified Tissue International, 2016; DOI: 10.1007/s00223-016-0174-y
FAQs to Improve Bone Density
What are the best exercises to improve bone density in females?
High-impact, weight-bearing exercises are the most effective. These are activities where you support your own body weight. Examples recommended by the Royal Osteoporosis Society and other health experts include jogging, dancing, hiking, tennis, and stair climbing. Muscle-strengthening exercises like lifting weights or using resistance bands are also crucial at least two days a week.
How much exercise is needed to see a difference?
The Swedish study showed clear benefits with 200 minutes of physical education per week. The American Heart Association recommends that kids ages 6-17 get at least 60 minutes of moderate- to vigorous-intensity activity daily, which should include bone-strengthening activities on at least three of those days.
Can you improve bone density after your teen years?
You reach peak bone mass around age 30, so the teen years are the most critical for building a strong foundation. A Purdue University study noted that high school is a time when girls can increase bone density at an unrivaled rate. However, you can still maintain bone density and slow bone loss later in life with consistent weight-bearing exercise and proper nutrition.
Does diet really matter more than exercise for bone health?
They are equally important and work together. Exercise stimulates the bone to become stronger, but your body needs the raw materials, primarily calcium and vitamin D, to actually build new bone tissue. A healthy diet and regular exercise are the cornerstones of a plan to improve bone density.
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