Some say that an hour’s exercise is good for the heart. A new study by the University of Oxford researchers now say that teenagers should exercise vigorously for at least 20 minutes per day to reap increased Cardio Respiratory Fitness (CRF).
The benefits of CRF plateaued after about20 minutes of vigorous exercise, with most adolescents reaching median CRF following about 14 minutes of exercise, , reported Oxford’s Alexander Jones, British Heart Foundation Intermediate Clinical Research Fellow in Paediatric Cardiovascular Medicine, and colleagues.
Though the WHO recommends vigorous exercise for about one hour per day for young adults, this goal is not met by 81% of adolescents, the researchers said. A shorter target of 20 minutes per day may be more attainable for teens as well as adults. They also argued that one possible reason why many teens do not meet the WHO goal is that the duration is quite long, requiring a daily time commitment that some may find difficult to maintain.
A target of 20 minutes might be easier to schedule daily and a focus on vigorous physical activity would simplify messages about the intensity of activity that is likely to improve CRF, they noted.
However, they warned that more research to examine the effect of a 20-minute exercise regime on other aspects of cardiometabolic health
METHOD
For this study. Jones and his team assessed physical activity and CRF in 339 children aged 13 to 14 (170 boys and 169 girls) from the Oxfordshire Sedentariness, Obesity, and Cardiometabolic Risk in Adolescents. They used wrist-worn accelerometers and 20-meter shuttle runs to calculate the effects of exercise on CRF. Moving average models were used to determine the relationships between physical activity variables and CRF. On average, girls exercised less often and had lower CRF versus boys.
