The physical activity levels of female adolescent New Zealanders

Abstract

Recently the health benefits of reducing sedentary lifestyles and the promotion of physical activity have become increasingly apparent The US Surgeon General's report on physical activity summarised the benefits of regular physical activity in disease prevention and the enhancement life. Despite the increasing body of knowledge that regular physical activity enhances health and reduces the risk of the development of some chronic diseases, research indicates that many adults remain sedentary. Research findings also indicate that adolescents and children are more active than adults, yet many do not engage in recommended levels of activity.

The present study aimed to determine the percentage of adolescent females who met the recommended international physical activity guidelines for adolescents. The guidelines recommend that all adolescents should be physically active almost daily as part of play, games work, sport, transportation, recreation, physical education or planned exercise, in family, school and community contexts. The guidelines also state that adolescents should engage in at least three sessions per week of physical activity that lasts twenty minutes or more which require moderate to vigorous levels of exertion.

Twelve females aged 15 years had their physical activity levels assessed by two methods. Physical activity was assessed by heart rate at one-minute intervals over 6 days, for 12 hours per day. Additionally self-administered questionnaires we’re used to determine subject's activity during the 4 weeks prior to the period of heart rate recording

For Guideline 1 attainment, criteria were defined in two ways; i) accumulated HR at 60-80% of maximal recorded heart rate (MRHR) for at least 30 minutes per day on at least 5 of the 6 days observed; ii) HR over 139 BPM for at least 30 minutes per day on at least 5 of the 6 days observed. For Guideline 2 attainment, criteria was defined as i) 60-80% of MRHR for at least 20 consecutive minutes per day on at least 3 of the 6 monitored days, or ii) a 'high' rating of activity by self-administered questionnaire.

Fifty-eight percent of subjects met Guideline 1 using criteria one indicating 42% of subjects were less active than recommended. Only 8% of subjects met Guideline 1 using criteria two. This was lower than the findings reported by Armstrong using a similar sample group in the United Kingdom. Eighty-three percent of subjects using the heart rate criteria outlined met Guideline 2 and only 50% of the subjects met Guideline 2 using a self-administered questionnaire.

Nearly half the sample group failed to meet the recommendation for physical activity to facilitate health, although a large majority of subjects met the requirements (by heart rate criteria) for vigorous physical activity designed to improve cardio-respiratory fitness. Although benefits will be accrued from this type of activity, there are more benefits to be gained in terms of blood glucose and blood lipid profiles by being active on more days of the week.

This study shows the difficulty in establishing accurate physical activity trends stemming from a lack of standardised methodology and threshold criteria to determine physical activity levels.

physical activity; female adolescents; methodology; physical activity trends; international physical activity guidelines; benefits