Middle school students in prime physical shape outperform their overweight and obese peers both on tests and grades, according to new research from Michigan State University.
The study, published Thursday in the Journal of Sports Medicine and Physical Fitness, claims to be the first study that links students' physical fitness to both objective (tests) and subjective (grades) forms of classroom evaluation. It examines how students' academic performance was affected by five aspects of physical fitness: body composition, cardiorespiratory endurance, flexibility, muscle strength, and muscular endurance.
"We looked at the full range of what's called health-related fitness," said lead researcher Dawn Coe in a statement. "Kids aren't really fit if they're doing well in just one of those categories."
Coe, who now serves as an assistant professor at the University of Tennessee, in Knoxville, conducted the study while she was a doctoral student in Michigan State's kinesiology department. She and her colleagues examined data from 312 middle school students (from 6th through 8th grade) at a Michigan school, all of whom had their physical fitness assessed through a series of five FITNESSGRAM tests.
The tests use criterion-based standards to assess whether students fall into the so-called Healthy Fitness Zone (HFZ), instead of benchmarking student fitness based on percentiles. In other words, students are expected to be able to perform X number of push-ups (based on age) to fall into the HFZ for upper-body strength and endurance, or X number of curl-ups to be in the HFZ for middle- and lower-body strength and endurance, respectively. (The new Presidential Youth Fitness Program, which will replace the Presidential Physical Fitness Test starting in the 2013-14 school year, will also use FITNESSGRAM tests to measure students' physical fitness.)
Students in the study were grouped based on how many times they fell into the HFZ during the five FITNESSGRAM tests. After assessing the grades and test scores of each student, the researchers discovered that students who fell into the HFZ in all five tests scored higher on subject-matter tests and got better grades than those students who only met the HFZ in two, three, or four of the five FITNESSGRAM tests.
Cardiorespiratory fitness (tested by a 20-meter shuttle run) and muscular strength and endurance (tested by pull-ups and curl-ups) were the health-related fitness components most strongly associated with academic achievement, according to the study. However, the researchers found no significant correlation between a student's body-fat percentage or flexibility and academic achievement.
The researchers are quick to stress that it's too soon to draw a causal link between fitness and improved academic performance. Instead, they urge further research into what's responsible for the relationship between academic achievement and physical fitness.
This study may be more robust in terms of types of fitness being assessed, but it's not the first to suggest some connection between students' physical fitness and academic performance. A study published in January found "strong evidence" of a link between physical activity and academic success, while a study published in June suggested a connection between childhood obesity and math performance.
However, much like this new Michigan State study, early findings from research funded by the Economic and Social Research Council (which were released back in July) urged caution before claiming a causal relationship between a child's weight and his or her academic performance. It, too, found heavier children to do "slightly worse in school," but when using "children's genetic markers to account for potentially other factors, [they] found no evidence that obesity causally affects exam results."
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