Silva announced his farewell on Monday in an emotional video message on Chelsea's website
Researchers, using government survey data from 1991 and 2007, found the amount of physical activity among US teens has not in fact changed significantly over the past two decades while the population, including children, has got heavier.
Researcher Youfa Wang, of Johns Hopkins University in Baltimore, said it came as a surprise to find that a lack of exercise was not to blame for the rise in obesity with nearly one-third of US children and teens now overweight or obese.
‘Although only one third of US adolescents met the recommended levels of physical activity, there is no clear evidence they had become less active over the past decade while the prevalence of obesity continued to rise,’ said Wang.
He said there was no evidence that teens’ exercise levels had changed appreciably at any time during the study period — even though those years saw an increase in teen obesity.
For the study published in the journal Obesity Reviews, Wang and colleagues used data from an annual government survey that tracks the health and lifestyle of US high school students.
Overall they found only 35 percent of teenagers surveyed in 2007 met the current recommendations for physical activity — performing activities that gets the heart rate up at least one hour per day, five or more days out of the week. But there was no evidence that teenagers’ exercise habits shifted significantly during the study period.
In 1993, for example, 66 percent of teens got enough short bursts of vigorous exercise — 20 minutes of running, biking or other heart-pumping activity at least three days per week. That figure was 64 percent in 2005. When it came to moderate exercise which should, according to guidelines, be performed at least 30 minutes per day, on five or more days per week, only 27 percent met that goal in 1999.
That figure was unchanged in 2005. On the other hand, there were some encouraging trends, according to Wang’s team. One was the recent increase in time spent in school physical education classes.
In 2007, 30 percent of high schoolers were taking a daily physical education class compared to 25 percent in 1995.
The researchers also found a decline in teenagers’ TV time. In 1999, 43 percent of students spent three or more hours watching TV on school days but this figure dipped to 35 percent in 2007. Wang said these findings suggest that waning exercise levels are ‘not likely the major explanation of the recent increase in obesity among US adolescents.’
He said other factors, like unhealthy diets, may be the driving force.
However, the researchers added that this does not mean it is fine for teenagers to be sedentary. Children and teens still need to develop regular exercise habits for the sake of their overall health, according to the researchers.
‘Our study suggests that more vigorous efforts are needed to help young Americans engage in adequate regular physical activity and reduce sedentary behaviors, which will help promote good health,’ they said.
Silva announced his farewell on Monday in an emotional video message on Chelsea's website
Protest organizers deny accusations of anti-Semitism, arguing that their actions are aimed at the Israeli government
Images published on the weekend showed Bollywood superstar actor Shah Rukh Khan sweating profusely while watching his team train
Al Ghadeer has offered the highest ROI of 7.65 per cent for affordable houses
Customer deposits and Islamic customer deposits increased by 2.5% to reach Dh39.5 billion
Bayern Munich will face Real Madrid in the first leg of the Champions League semifinal on Tuesday
Company’s mobile customer base grew 5.7% year-over-year to 8.7 million subscribers
UK foreign secretary says the proposal includes 40-day pause in fighting and release of thousands of Palestinian prisoners and Israeli hostages