05. tbl. 98. árg. 2012
Body Composition, Aerobic Fitness, Physical Activity and Metabolic Profile among 18 Year Old Icelandic High-School Students
Holdafar, úthald, hreyfing og efnaskiptasnið meðal 18 ára íslenskra framhaldsskólanema
Objective: The purpose of the study was to examine metabolic risk factors among 18 year old high-school students and compare students attending vocational and traditional schools.
Material and methods:Participants (147 boys and 130 girls) were randomly selected. Physical activity (PA) was measured with pedometers and aerobic fitness (fitness) with maximal oxygen uptake test on a treadmill. Height, weight, waist circumference (WC), and body mass index (BMI) were measured and percentage body fat (%Fat) assessed with dual energy X-ray absorptiometry. Resting blood pressure (BP) and serum lipids and glucose were measured.
Results: According to BMI, 23% of the students were overweight/obese, 20% had elevated WC, and 51% increased %Fat. In addition, 11% of the students had high-density lipoprotein below recommended levels, and 8% had low-density lipoprotein and 9% triglycerides above advised values. Finally, 10% had borderline or high systolic BP. In contrast, 84% of the students had fair or higher levels of fitness, although only 34% reached recommended levels of daily PA. According to %Fat, a higher proportion of boys (33%) than girls (22%) were classified as obese (p=0.042) but a higher proportion of boys (57%) were very fit (57 vs. 24%, p<0.001). Vocational students had lower levels of fitness (Cohen´s d (Cd)=0.7) and PA (Cd=0.7), and higher %Fat (Cd=0.5), WC (Cd=0.6), and BP (Cd=0.3, p<0.05).
Conclusion:Although fitness among 18 year old Icelandic high-school students seems generally good, their PA is low and %Fat elevated. Serum lipids and systolic BP are also increased in about 10% of the teenagers. Vocational students measure worse on most metabolic risk factors than traditional students.
Arngrimsson SA, Richardsson EB, Jonsson K, Olafsdottir AS
Center for Sport and Health Sciences, University of Iceland, Laugarvatn, Iceland
Tables
Table I: Metabolic risk factors among participants.
| Girls | Boys | |||||
| Variables | School 1 | School 2 | School 3 | School 1 | School 2 | School 3 |
|
Height (cm) |
168.6±6.5 (n=53) |
167.7±4.8 (n=51) |
166.9±5.0 (n=25) |
182.9±7.1 (n=50) |
183.7±6.0 (n=50) |
178.7±4.9*† (n=46) |
|
Weight (kg) |
63.7±7.4 (n=53) |
61.0±7.1 (n=50) |
60.6±8.6 (n=20) |
76.1±11.2 (n=49) |
76.8±10.8 (n=50) |
76.5±15.0* (n=42) |
|
BMI (kg/m2) |
22.5±3.1 (n=53) |
21.9±2.8 (n=51) |
23.7±4.7 (n=24) |
22.8±3.1 (n=49) |
22.9±2.9 (n=50) |
23.5±3.8 (n=40) |
|
Waist circ. (cm) |
76.9±7.1 (n=53) |
73.5±7.2 (n=51) |
77.6±11.7 (n=25) |
81.6±8.0 (n=49) |
80.3±6.3 (n=50) |
82.7±10.8*† (n=42) |
|
Body fat (%) |
31.5±5.2 (n=50) |
28.9±4.9 (n=49) |
35.2±7.6 (n=19) |
19.1±5.9 (n=47) |
18.5±5.9 (n=50) |
23.8±9.3*† (n=35) |
| Blood Press. | ||||||
| Systolic | 116.6±10.2 | 118.9±8.8 | 118.8±9.9 | 122.3±9.4 | 124.9±8.9 | 128.4±13.0*† |
|
Diastolic (mmHg) |
70.3±7.1 (n=53) |
70.2±5.7 (n=51) |
72.3±6.3 (n=24) |
68.8±6.8 (n=50) |
70.0±6.3 (n=50 |
75.2±7.0† (n= 46) |
| VO2max (ml/kg/min) |
39.9±5.1 (n=47) |
42.1±5.4 (n=47) |
35.8±5.0 (n=18) |
52.3±6.3 (n=47) |
54.3±6.0 (n=50) |
46.5±8.2*† (n=34) |
| PA (Ksteps/day) |
9.28±2.50 (n=45) |
8.86±2.76 (n=46) |
7.54±3.73 (n=15) |
9.72±2.93 (n=44) |
8.84±2.60 (n=44) |
6.88±2.39† (n=17) |
| Cholesterol | 4.8±0.8 | 4.4±0.7 | 4.5±0.7 | 4.1±0.6 | 4.0±0.5 | 4.4±0.9* |
| HDL | 1.6±0.3 | 1.6±0.3 | 1.5±0.4 | 1.3±0.2 | 1.3±0.2 | 1.2±0.2* |
| LDL | 2.7±0.7 | 2.3±0.7 | 2.5±0.7 | 2.4±0.6 | 2.2±0.5 | 2.5±0.8† |
| Triglycerides | 1.1±0.5 | 1.1±0.4 | 1.0±0.4 | 1.0±0.3 | 0.9±0.4 | 1.2±0.4 |
|
Glucose (mmol/L) |
4.5±0.3 (n=50) |
4.4±0.3 (n=50) |
4.5±0.3 (n=20) |
4.6±0.3 (n=48) |
4.6±0.3 (n=49) |
4.7±0.4* (n=34) |
BMI = body mass index, Waist circ. = waist circumference, Blood press. = blood pressure, VO2max = maximal oxygen uptake, PA = physical activity, HDL = high-density lipoprotein, LDL = low-density lipoprotein. * = significant gender difference (p<0.05). † = significant school difference (p<0.05).
Table II: Participant body composition classification according to body mass index and percentage body fat.
| Classification | Girls | Boys | ||
| Body mass index | kg/m2 | % (n) | kg/m2 | % (n) |
| Underweight | <18.5 | 8.5 (11) | <18.5 | 2.1 (3) |
| Normal weight | -24.9 | 72.1 (93) | -24.9 | 71,0 (103) |
| Overweight | -29.9 | 14.7 (19) | -29.9 | 17.9 (26) |
| Obesity | >30.0 | 4.7 (6) | >30.0 | 9.0 (13) |
| Body fat percentage13 | % | % | ||
| Not recommended | <20.0 | 2.5 (3) | <8.0 | 0,0 (0) |
| Low | -24.0 | 8.5 (10) | -10.5 | 4.5 (6) |
| Mid | -31.5 | 46.6 (55) | -17.5 | 37.3 (50) |
| Upper | -35.0 | 20.3 (24) | -22.0 | 25.4 (34) |
| Obesity | >35.0 | 22.0 (26) | >22.0 | 32.8 (44) |
The cut-offs for the classification categories between the highest and the lowest categories span from the cut-off for the category in the next row above to the cut-off for the category in question (for example, those who are classified as overweight have body mass index from 25.0 kg/m2 to 29.9 kg/m2).
Table III: Participant blood pressure classification.
| Classification | Systolic | Diastolic | Girls | Boys | ||
| Blood pressure | mmHg | mmHg | % (n) | % (n) | % (n) | % (n) |
| Ideal | <120.0 | <80.0 | 58.6 (75) | 90.6 (116) | 33.6 (49) | 83.6 (122) |
| Normal | -134.9 | -84.9 | 37.5 (48) | 6.3 (8) | 50.7 (74) | 13.0 (19) |
| Borderline-high | -140.0 | -90.0 | 1.6 (2) | 2.3 (3) | 10.3 (15) | 2.7 (4) |
| Hypertension | >140.0 | >90.0 | 2.3 (3) | 0.8 (1) | 5.5 (8) | 0.7 (1) |
The cut-offs for the classification categories between the highest and the lowest categories span from the cut-off for the category in the next row above to the cut-off for the category in question (for example, those who are classified with normal systolic blood pressure have systolic blood pressure from 120 mmHg to134.9 mmHg). The column to the left for girls and boys indicates prevalence for systolic blood pressure and the column to the right indicates prevalence for diastolic blood pressure.
Table IV: Participant aerobic fitness and physical activity classification.
| Classification | Girls | Boys | ||
| Aerobic fitness15 | ml/kg/min | % (n) | ml/kg/min | % (n) |
| Very poor | <31.59 | 4.5 (5) | <38.00 | 5.3 (7) |
| Poor | -35.49 | 17.9 (20) | -42.19 | 4.6 (6) |
| Fair | -39.49 | 24.1 (27) | -45.69 | 9.2 (12) |
| Good | -43.99 | 29.5 (33) | -51.09 | 24.4 (32) |
| Excellent | >44.00 | 24.1 (27) | >51.10 | 56.5 (74) |
| Physical activity16 | steps/day | steps/day | ||
| Sedentary | <5000 | 8.5 (9) | <5000 | 7.5 (8) |
| Low active | -7499 | 25.5 (27) | -7499 | 24.5 (26) |
| Somewhat active | -9999 | 30.2 (32) | -9999 | 34.9 (37) |
| Active | -12499 | 28.3 (30) | -12499 | 21.7 (23) |
| Very active | >12500 | 7.5 (8) | >12500 | 11.3 (12) |
The cut-offs for the classification categories between the highest and the lowest categories span from the cut-off for the category in the next row above to the cut-off for the category in question (for example, girls who are classified with good aerobic fitness have maximal oxygen uptake from 39.50 ml/kg/min to 43.99 ml/kg/min).
Figure captions
Figure I: The proportion of participants above recommended levels for blood lipids and blood glucose. The values in the bars indicate number of participants above recommended levels. LDL = low-density lipoproteins, HDL = high-density lipoproteins. Total cholesterol >6.00 mmol/L17, LDL >3.35 mmol/L17, HDL <1.30 mmol/L (girls) <1.05 mmol/L (boys)17, triglycerides >1.70 mmol/L17, blood glucose >5.60 mmol/L18.
Figure II: Comparison of body composition classification between body mass index and percentage body fat for girls (A) and boys (B).