An increase in time spent in physical education class helps kids develop stronger muscles and that increasing weekly physical activity does not increase the risk of bone fractures, says a new Swedish study.  There is only one problem: P.E. time in the U.S. is going the other way.
In the study, published in the journal Medicine & Science in Sports & Exercise, a large group of students in one Swedish school received increased physical education for 60 minutes per day or 200 minutes per week for 2 years, while a control group continued to exercise the standard 40 minutes per day.
Researchers then compared the two groups using several measurements, including body weight and height, concentric isokinetic knee extension to test muscle strength, vertical jump height, lifestyle and physical activity habits.
"Regular weight-bearing exercise has been shown to consistently improve bone mass, structure and strength during childhood and adolescence," said the author, Bjarne Löfgren, M.D., of Lund University in Sweden.
"It can also help reduce the risk of musculoskeletal diseases later on in adult years."
"The results of this study showed that the increase in school-based physical activity time produced greater muscle mass and/or strength," he said. "This could have important implications on public health guidelines and recommendations for school-based physical activity."
Dr. Löfgren's study complements a growing body of evidence linking students' physical activity levels to increased academic achievement. 
Decline in P.E. leading to soaring child obesity rates
The problem is that a declining number of children and adolescents in the United States get anything close to 60 minutes a day of physical education, much less the 40 minutes a day that is standard in Sweden. The adverse health consequences of the decline are enormous.
As a 2009 story published on ESPN Outside the LInes notes, "Put simply, at a time when every penny is being pinched by every school in every district in every county in every state, physical education is taking a beating. The experts and educators say there is no doubt that the erosion of P.E. has been a major contributor to the skyrocketing obesity rates."
As the story goes on to point out, the childhood obesity statistics are numbing:
- 20 percent of U.S. children will be defined as obese next year, according to the Department of Health and Human Services. That's about four times what the rate was in the 1970s. Using the body mass index (BMI), which is a measure of one's weight in relation to height, obesity is defined as being at or above the 95th percentile based on standards established in the 1970s for kids who are the same age and sex.
- Between 1971 and 2006, the number of 6-to-11-year-olds considered overweight more than quadrupled -- from 4 percent to 17 percent, according to the Centers for Disease Control and Prevention.
- There's a 70-80 percent chance that an obese child will become an obese adult.
- $14 billion is spent annually on child obesity-related health care costs, American Heart Association president Dr. Tim Gardner said during a recent press conference. Overall, annual obesity-related costs total $117 billion.
Equally startling, says ESPN, are the numbers reflecting the state of P.E. programs in public schools across the country:
- Only 3.8 percent of elementary schools, 7.9 percent of middle schools and 2.1 percent of high schools provide daily P.E., according to a CDC survey. A study published in the 2007 issue of Health Economics stated that daily P.E. for high school students declined from 41.6 percent in 1991 to 28.4 percent in 2003. (The survey did not have statistics for middle and elementary schools.)
- 22 percent of schools don't require kids to take any P.E.
- Nearly half -- 46 percent -- of high school students were not attending any P.E. classes when surveyed by the CDC.
For more on the US Physical Activity Guidelines, click here.
Source: The American College of Sports Medicine.
1. Löfgren B, Daly R, Nilsson J-A, Denker M, Karlsson Magnus K. An Increase in School-Based Physical Education Increases Muscle Strength in Children. Med Sci Sports Exer 2013;45(5):997-1003. DOI: 10.1249/MSS.0b013e31827c0889
2. CDC. Physical Inactivity and Unhealthy Dietary Behaviors and Academic achievement; CDC. The association between school based physical activity, including physical education, and academic performance. Atlanta, GA: U.S. DHHS; 2010