Figure 1
Participant flow diagram showing recruitment, exclusions, and the final analytical sample of adolescent men in the MOPO study conducted during military call-ups in Oulu, Finland (2009–2013).
Table 1
Characteristics of study participants (n = 3.389) by body mass index (BMI) categories. Values are presented as means (SD) unless otherwise indicated.
| VARIABLE | BMI | ||||
|---|---|---|---|---|---|
| <18.5 N = 268 | 18.5 < 24.9 N = 2309 | 25 ≤ 29.9 N = 598 | ≥30 N = 214 | p VALUE | |
| Height, cm | 178.0 (6.5) | 177.9 (6.2) | 178.0 (6.6) | 177.4 (7.3) | 0.658 |
| Weight, kg | 55.7 (4.7)* | 68.7 (7.4) | 84.7 (7.7)* | 106.5 (14.0)* | <0.001 |
| BMI, kg/m2 | 17.5 (0.8)* | 21.6 (1.7) | 26.7 (1.3)* | 33.9 (3.6)* | <0.001 |
| Body fat, % | 9.3 (2.9)* | 13.6 (4.9) | 22.6 (6.1)* | 34.9 (6.5)* | <0.001 |
| Waist circumference, cm | 70.1 (3.4)* | 78.3 (5.0) | 90.0 (6.1)* | 106.7 (9.9)* | <0.001 |
| HR, beats/min | 75.9 (12.7)* | 72.9 (12.3) | 73.2 (11.9) | 76.7 (13.2)* | <0.001 |
| Daily smoking, n (%) | 56 (20.9) | 430 (18.2) | 102 (17.1) | 41 (19.2) | 0.626 |
| Daily snuffing, n (%) | 18 (6.7) | 306 (13.0) | 88 (14.7) | 18 (8.4) | <0.001 |
| Weekly alcohol consumption, n (%) | 32 (11.9) | 312 (13.2) | 99 (16.6)* | 29 (13.6) | 0.047 |
| Diabetes, n (%) | 3 (1.1) | 10 (0.4) | 4 (0.7) | 0 (0.0) | 0.283 |
| Mental disorders, n (%) | 23 (8.6) | 181 (7.7) | 45 (7.5) | 26 (12.1) | 0.130 |
| Thyroid disorders, n (%) | 2 (0.7) | 6 (0.3) | 0 (0.0) | 0 (0.0) | 0.173 |
| Asthma, n (%) | 19 (7.1) | 147 (6.2) | 52 (9.7) | 25 (11.7)* | 0.008 |
| Musculoskeletal diseases, n (%) | 35 (13.1) | 283 (12.0) | 76 (12.7) | 38 (17.8) | 0.111 |
[i] *Statistically significant difference (p < 0.05) compared to those with normal weight.
BMI = body mass index.
SD = standard deviation.
HR = heart rate.
Figure 2
Mean (SD) heart rate variability (ln rMSSD) values by physical activity level across body mass index categories in adolescent men (n = 3.389).
Statistically significant differences (p < 0.05) between PA (physical activity) groups: * vs. low PA, vs mod PA, # vs all other PA groups.
Low PA = no regular physical activity, occasional walking, < 0.5 h/week).
Moderate PA = regular recreational PA or moderate occupational PA, 0.5–2 h/week.
High PA = regular heavy physical exercise, 2–4 h/week or heavy physical exercise at least 5 times a week, >4 h/week.
Table 2
Mean (SD) values of heart rate variability indices by physical activity level across body mass index categories in adolescent men (n = 3.389).
| HRV VARIABLES | PA | ||
|---|---|---|---|
| LOW N = 815 | MODERATE N = 1229 | HIGH N = 1345 | |
| BMI < 18.5, n = 268 | n = 109 | n = 101 | n = 58 |
| RRi (ms) | 791 (124) | 824 (133) | 853 (176)* |
| rMSSD (ln, ms) | 3.68 (0.62) | 3.85 (0.65)* | 3.81 (0.71)* |
| rMSSD (ms) | 47.5 (28.0) | 56.4 (33.3) | 56.2 (35.4) |
| SDNN (ms) | 49.6 (24.7) | 56.5 (26.1) | 55.4 (29.2) |
| pNN50 (%) | 24.3 (20.4) | 29.9 (22.0) | 29.1 (23.1) |
| LFpower (ln) | 6.56 (1.07) | 6.85 (1.09) | 6.79 (1.18) |
| HFpower (ln) | 6.70 (1.26) | 6.87 (1.32) | 6.73 (1.37) |
| LF/HF | 1.00 (0.16) | 1.02 (0.17) | 1.03 (0.18) |
| BMI 18.5–24.9, n = 2309 | n = 479 | n = 819 | n = 1011 |
| RRi (ms) | 807 (126) | 839 (139)* | 882 (145)* |
| rMSSD (ln, ms) | 3.66 (0.64) | 3.79 (0.63)* | 3.88 (0.58)* |
| rMSSD (ms) | 46.0 (25.9) | 52.7 (30.3)* | 56.5 (30.4)* |
| SDNN (ms) | 47.8 (22.6.) | 52.7 (24.5)* | 56.0 (24.7)* |
| pNN50 (%) | 24.1 (20.1) | 28.2 (21.5)* | 31.0 (21.2)* |
| LFpower (ln) | 6.58 (1.00) | 6.73 (1.01)* | 6.93 (1.02)* |
| HFpower (ln) | 6.57 (1.24) | 6.80 (1.21)* | 6.91 (1.14)* |
| LF/HF | 1.02 (0.17) | 1.01 (0.16) | 1.02 (0.15) |
| BMI 25–29.9, n = 598 | n = 152 | n = 214 | n = 232 |
| RRi (ms) | 805 (127) | 829 (124) | 891 (150)* |
| rMSSD (ln, ms) | 3.65 (0.62) | 3.71 (0.59) | 3.86 (0.58)* |
| rMSSD (ms) | 46.2 (27.5) | 48.0 (26.7) | 55.2 (30.3)* |
| SDNN (ms) | 46.6 (22.2) | 50.1 (22.6) | 53.6 (23.1)* |
| pNN50 (%) | 22.8 (19.1) | 24.5 (19.9) | 29.9 (21.5)* |
| LFpower (ln) | 6.54 (0.92) | 6.75 (0.91) | 6.87 (0.91) |
| HFpower (ln) | 6.48 (1.23) | 6.63 (1.19) | 6.77 (1.13) |
| LF/HF | 1.03 (0.15) | 1.04 (0.16) | 1.03 (0.14) |
| BMI ≥ 30, n = 214 | n = 75 | n = 95 | n = 44 |
| RRi (ms) | 774 (139) | 817 (114) | 856 (154)* |
| rMSSD (ln, ms) | 3.39 (0.74) | 3.69 (0.63)* | 3.78 (0.73)* |
| rMSSD (ms) | 36.8 (22.0) | 48.6 (33.3)* | 54.3 (32.2)* |
| SDNN (ms) | 39.0 (19.5) | 48.8 (25.8)* | 52.4 (26.7)* |
| pNN50 (%) | 17.3 (16.9) | 24.6 (22.5) | 29.1 (21.8)* |
| LFpower (ln) | 6.27 (0.99) | 6.67 (0.96) | 6.86 (1.09)* |
| HFpower (ln) | 6.02 (1.47) | 6.55 (1.23) | 6.68 (1.38)* |
| LF/HF | 1.09 (0.22) | 1.03 (0.14) | 1.05 (0.18) |
[i] *Statistically significant difference (p < 0.05) compared with low physical activity group.
Low = no regular PA, occasional walking, < 0.5 h/week).
Moderate = regular recreational PA or moderate occupational PA, 0.5–2 h/week.
High = regular heavy physical exercise, 2–4 h/week or heavy physical exercise at least 5 times a week, >4 h/week.
HRV = heart rate variability.
BMI = body mass index.
RRi = R-R interval.
ms = millisecond.
rMSSD = Root Mean Square of Successive Differences.
ln = logarithmus naturalis.
SDNN = Standard Deviation of NN intervals.
pNN50 (%) = Percentage of NN50.
LFpower (ln) = Low Frequency Power.
HFpower (ln) = High Frequency Power.
LF/HF = Low Frequency to High Frequency Ratio.
SD = standard deviation.
Determinants of HRV according to multivariable linear regression analyses.
Table 3
Factors associated with heart rate variability (ln rMSSD) in adolescent men with underweight, normal weight, overweight, and obesity (n = 3.389), based on multivariable linear regression analyses.
| VARIABLE | REGRESSION COEFFICIENT (95% CI) | SE | p VALUE |
|---|---|---|---|
| Underweight (BMI < 18.5) | |||
| ln rMSSD: model R2 = 0.038, standard error of the estimate = 0.64, p = 0.015 | |||
| Waist circumference | –0.151 | 0.013 | p = 0.026 |
| Constant | 5.919 | 0.911 | p < 0.001 |
| Normal weight (18.5 < BMI < 25) | |||
| ln rMSSD: model R2 = 0.042, standard error of the estimate = 0.60, p < 0.001 | |||
| Self-reported physical activity | 0.137 | 0.015 | p < 0.001 |
| Constant | 3.526 | 0.099 | p < 0.001 |
| Overweight (25 ≤ BMI < 30) | |||
| ln rMSSD: model R2 = 0.059, standard error of the estimate = 0.58, p = 0.001 | |||
| Self-reported physical activity | 0.104 | 0.029 | p = 0.030 |
| Waist circumference | –0.097 | 0.005 | p = 0.045 |
| Constant | 4.602 | 0.454 | p < 0.001 |
| Obesity (BMI ≥30) | |||
| ln rMSSD: model R2 = 0.074, standard error of the estimate = 0.68, p = 0.001 | |||
| Self-reported physical activity | 0.172 | 0.065 | p = 0.024 |
| Waist circumference | –0.168 | 0.005 | p = 0.028 |
| Constant | 4.600 | 0.624 | p < 0.001 |
[i] Models were adjusted for other significant variables in univariate analysis (stress, smoking and snuffing (15 min before), coffee (15 min before)).
Low PA = no regular physical activity, occasional walking, < 0.5 h/week).
Moderate PA = regular recreational PA or moderate occupational PA, 0.5–2 h/week.
High PA = regular heavy physical exercise, 2–4 h/week or heavy physical exercise at least 5 times a week, >4 h/week.
HRV = heart rate variability.
rMSSD = root mean square of successive differences.
BMI = body mass index.
SE = standard error of the estimate.