The longitudinal association between objectively measured physical activity and mental health among Norwegian adolescents

Table 1 Descriptive characteristics of the study sample by sex, all time points (mean ± SD unless otherwise specified)

Characteristic	Time 1 (2016) n = 599	Time 2 (2017) n = 581	Time 3 (2018) n = 552
Age
Boys	13.4 (0.3)	14.4 (0.3)	15.4 (0.3)
Girls	13.3 (0.3)	14.3 (0.3)	15.3 (0.3)
Height (cm)
Boys	163.9 (8.6)	171.3 (8.2)	176.9 (7.5)
Girls	161.7 (6.9)	165.0 (6.6)	166.3 (6.4)
Weight (kg)
Boys	53.0 (11.8)	60.7 (13.5)	66.8 (13.6)
Girls	52.8 (9.9)	56.6 (9.8)	59.2 (9.8)
BMI (kg/m²)
Boys	19.6 (3.3)	20.5 (3.7)	21.3 (3.7)**
Girls	20.0 (3.1)	20.8 (3.0)	21.4 (3.0)**
MHP
Boys	9.7 (5.4)	10.1 (5.3)	10.4 (5.2)
Girls	10.0 (5.1)	11.3 (5.8)	12.0 (5.3)**
MWB
Boys	57.1 (9.1)	57.3 (9.4)	55.9 (9.6)
Girls	55.0 (8.9)	52.2 (10.5)	50.6 (11.0)**
Total PA (cpm/d)
Boys	474.4 (178.7)	476.8 (177.5)	460.9 (204.7)
Girls	402.2 (118.6)	399.9 (127.5)	383.5 (138.3)*
SED (min/d)
Boys	548.4 (74.4)	541.7 (78.7)	542.1 (99.6)*
Girls	565.7 (55.4)	561.3 (64.6)	564.1 (69.6)
LPA (min/d)
Boys	172.2 (34.1)	167.6 (34.3)	140.8 (37.3)**
Girls	161.4 (32.3)	153.9 (32.2)	137.6 (30.4)**
MVPA (min/d)
Boys	63.9 (22.9)	62.4 (24.3)	58.1 (26.7)*
Girls	54.0 (18.5)	53.6 (19.4)	50.1 (21.4)*
Meeting act.rec (%)
Boys	53.3	53.6	43.8
Girls	36.3	37.1	29.5

Note. BMI Body mass index, MHP Mental health problems, MWB Mental wellbeing, Total PA (cpm/d) = average daily counts per minute, SED = average daily sedentary behaviour, LPA = average daily light physical activity, MVPA = average daily moderate to vigorous physical activity, Meeting act.rec = meeting national recommendations for PA, min/d = minutes per day
* Significant change of variable between T1 to T3, p ≤ .05. Tests are performed on subsamples with valid measurements on outcome variable in T1 and T3 (n = 177–269)
** Significant change of variable between T1 to T3, p ≤ .001. Tests are performed on subsamples with valid measurements on outcome variable in T1 and T3 (n = 177–269)

ISSN: 1479-5868