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Table 2 Baseline characteristics of participants in the cohort study

From: The relationship between physical activity, mental wellbeing and symptoms of mental health disorder in adolescents: a cohort study

Continuous variablesAllFemalesMales
nMean (SD)nMean (SD)nMean (SD)
Age in years67312.69 (0.34)34312.68 (0.34)33012.70 (0.34)
SDQ Total Difficulties Score (SDQ TDS)63712.41 (5.76)32812.33 (5.67)30912.50 (5.87)
Physical activity volume (mean counts per minute (cpm))673508.28 (169.42)343465.93 (153.25)330552.31 (174.35)
Physical activity intensity (mean daily MVPA minutes)67355.59 (21.47)34349.85 (19.24)33061.56 (22.07)
Categorical variablesnCategoryAllFemalesMales 
n (%)n (%)n (%) 
Gender673  343 (51.0)330 (49.0) 
Ethnicity673White629 (93.0)320 (93.3)309 (93.6) 
Other44 (7.0)23 (6.7)21 (6.4) 
Family Affluence Scale (SES)673Low and Med (0–5)353 (52.0)187 (54.5)166 (50.3) 
High (6–9)320 (48.0)156 (45.5)164 (49.7) 
Study school6731142 (21.0)79 (23.0)63 (19.1) 
2116 (17.0)64 (18.7)52 (15.8) 
3134 (20.0)62 (18.1)72 (21.8) 
481 (12.0)41 (12.0)40 (12.1) 
5142 (21.0)59 (17.2)83 (25.2) 
658 (9.0)38 (11.1)20 (6.1) 
Intervention arm of the AHEAD trial673Intervention339 (50.4)184 (54.3)155 (45.7) 
Control334 (49.6)159 (47.6)175 (52.4) 
Sleep665Good sleep348 (52.0)169 (50.0)179 (55.0) 
Poor sleep317 (48.0)172 (50.0)145 (45.0) 
Smoking667Yes115 (17.0)71 (20.9)44 (13.5) 
No552 (83.0)269 (79.1)283 (86.5) 
Drinking alcohol603Don’t drink29 (4.8)11 (3.5)18 (6.2) 
Occasional352 (58.4)198 (63.7)154 (52.7) 
Weekly176 (29.2)84 (27.0)92 (31.5) 
Frequent46 (7.6)18 (5.8)28 (9.6) 
Number of friends663None4 (0.6)0 (0.0)4 (1.2) 
1–267 (10.1)33 (9.7)34 (10.5) 
3–6250 (37.7)133 (39.1)117 (36.2) 
7 or more342 (51.6)174 (51.2)168 (52.0) 
Belonging to teams or clubs666Yes321 (48.2)135 (39.6)186 (57.2) 
No345 (51.8)206 (60.4)139 (42.8)