Tuesday, June 25, 2013

Exercise is Associated with Better Eating Habits in Children

A recent study at Blaise Pascal University and Clermont University in France explored the relationship between poor eating behaviors and exercise in 278 children (147 girls) between the ages of 6 and 10. The researchers measured height, weight, body mass index, an adiposity index from skinfold measurements, and two measures of fitness: a 20-meter shuttle run and a squat jump test for height.  They identified the following eating behaviors as “high risk” when they occurred frequently: skipping breakfast; snacking; TV viewing during meals; and sweetened beverage consumption. Dietary habits were obtained from a validated questionnaire completed by parents in the present of the child.  106 children presented with one risk factor, 46 children had 2 eating risk factors, and 20 had at least 3 factors. Children who ate breakfast every day were fitter than those who ate breakfast sometimes or never.  Children who snacked everyday had significantly lower vertical jumps than those who rarely or never ate breakfast.  These results were independent of obesity.

The bottom line of this research is that unhealthy eating habits in elementary school children appear to be associated with poorer fitness. The authors believe that progressive lifestyle interventions which change a child's eating habits step by step may lead to progressive improvements in physical fitness.

Read more about the study here.

Sunday, June 16, 2013

Running on the Moon

One of the key questions that remains unanswered as we prepare to send humans to other planetary surfaces is the degree to which living and exercising in these reduced gravity environments will provide an osteoprotective stimulus to prevent bone loss that is currently seen on International Space Station missions. 

With support from the National Space Biomedical Research Institute and the NASA Flight Opportunities Program, our research team from the Department of Orthopaedics and Sports Medicine at the University of Washington conducted a parabolic flight experiment to validate the activity monitoring system that was worn by subjects exercising in microgravity.  Nine subjects were tested as they performed a series of locomotor activities with the sensors positioned on the mid-lower back and around the ankle. Subjects were secured to the surface of the treadmill via a subject load device to provide loads similar to those experienced on Earth. Over two flight campaigns, activities were performed in three conditions:  zero, lunar, and Martian gravity.  An image of a subject running in zero-G with a simulated lunar load is shown below. 

With the acquired parabolic flight data, the team is developing classification software to autonomously recognize activities performed in reduced gravity.  Validation of this system would improve the ability to monitor exercise designed to preserve the bone health of astronauts aboard the ISS and on future exploration missions.  Similar methods could be applied to address the prevention of osteoporosis on Earth.

ACL Injury and the Menstrual Cycle

It has long been known that women have a highly elevated risk for rupture of the anterior cruciate ligament (ACL) in the knee compared to men engaged in the same activity. One of the many theories to explain this risk is that the increase in circulating estrogen and degrease in progesterone during the pre-ovulatory stage of the menstrual cycle reduces the strength of the ligament. A group of researchers from the Nollet Musculo-skeletal System Institute in Paris studied 172 pre-menopausal women (mean age 34 years) with regular cycles who tore their ACL while skiing. The accidents mainly occurred on blue (moderately difficult) slopes at medium speed and the ski bindings did not release in most patients.  The authors found that ACL injury was 2.4 times more likely to occur in a pre-ovulatory phase of the cycle compared to the post-ovulatory phase. This pattern was not affected by the use of oral contraceptives. 

Bottom Line:    The findings suggest that women engaged in risky recreational exercise during the pre-ovulatory stage of their menstrual cycles could decrease their risk of injury by taking special precautions.  In skiing this might involve skiing on less demanding runs and adjusting release bindings to a lower threshold.  Read more about the study published in the June 2013 issue of the journal Orthopaedics and Traumatology, Surgery and Research here