Run Daddy Run! A Lifestyle Intervention Focusing on Fathers and Their Children

Father-child co-physical activity, will be subjectively measured using a seven-day recall diary, in which fathers will be asked to report all physical activities and screen time activities they performed together with their child in the last 7 days. More specifically, fathers have to report the start hour of the activity/activities, duration of the activity/activities, and the activity/activities itself in this diary, for each day of the week. PA diaries are often economical and can provide information on the types of activity not recorded from more objective measurement methods, such as accelerometers [66]. According to Matthews et al. (2002), diary based self-reported instruments can provide, with good participation compliance, accurate and valid assessments of PA [67].

Objective PA data will be collected through accelerometry. Axivity's (model AX3, 3-axial) will be worn by the father and the child for at least 7 consecutive days, on the non-dominant hand, for 24 hours a day. Participants' light (LPA), moderate (MPA), vigorous (VPA) and total PA will be assessed during this time period, which have been shown to be reliable and valid [60]. As an additional measure of (self-report) PA, fathers will be asked to complete the International Physical Activity Questionnaire Short Form (IPAQ-SF), for both himself and his child, questioning LPA, MPA and VPA during the past seven days [61, 62].Research comparing the IPAQ-SF with objective measures (i.e. accelerometers) shows that the criterion validity of this questionnaire is fair to good, with an ICC 0.30 [62]. Overall, the IPAQ-SF has reasonable (test-retest) reliability (ICC=0.65) a good internal consistency (Cronbach's Alpha=0.83) [63].

Objective PA data will be collected through accelerometry. Axivity's (model AX3, 3-axial) will be worn by the father and the child for at least 7 consecutive days, on the non-dominant hand, for 24 hours a day. Participants' light (LPA), moderate (MPA), vigorous (VPA) and total PA will be assessed during this time period, which have been shown to be reliable and valid [60]. As an additional measure of (self-report) PA, fathers will be asked to complete the International Physical Activity Questionnaire Short Form (IPAQ-SF), for both himself and his child, questioning LPA, MPA and VPA during the past seven days [61, 62].Research comparing the IPAQ-SF with objective measures (i.e. accelerometers) shows that the criterion validity of this questionnaire is fair to good, with an ICC 0.30 [62]. Overall, the IPAQ-SF has reasonable (test-retest) reliability (ICC=0.65) a good internal consistency (Cronbach's Alpha=0.83) [63].

Co-ST will be measured using a seven-day recall diary, in which fathers will be asked to report all physical activities and screen time activities they performed together with their child in the last 7 days. More specifically, fathers have to report the start hour of the activity/activities, duration of the activity/activities, and the activity/activities itself in this diary, for each day of the week. PA diaries are often economical and can provide information on the types of activity not recorded from more objective measurement methods, such as accelerometers [66]. According to Matthews et al. (2002), diary based self-reported instruments can provide, with good participation compliance, accurate and valid assessments of PA [67].

For measuring SB of the father, objective data will also be collected through accelerometry described under "Physical activity" measurements. Participants' SB will be assessed during a 7 days period using Axivity's, which have been shown to be a reliable and valid measure for SB. Additionally, SB (including ST) will be assessed using the International Sedentary Assessment Tool (ISAT) questionnaire [64]. This questionnaire has a good internal consistency (reliability) (Cronbach Alpha=0.80) and good criterion validity (interclass correlation r=0.63) [65]. In the ISAT, SB is questioned on week- and weekend days, as well as specific ST-related behaviours are questioned (i.e. TV/DVD viewing, computer/laptop/PlayStation use and smartphone/tablet use). The mean daily SB and ST of the fathers and their children will be calculated using the following formula: (SG or ST weekdays × 5 + SG or ST weekend days × 2) / 7.

For measuring SB of the child, objective data will also be collected through accelerometry described under "Physical activity" measurements. Participants' SB will be assessed during a 7 days period using Axivity's, which have been shown to be a reliable and valid measure for SB. Additionally, SB (including ST) will be assessed using the International Sedentary Assessment Tool (ISAT) questionnaire [64]. This questionnaire has a good internal consistency (reliability) (Cronbach Alpha=0.80) and good criterion validity (interclass correlation r=0.63) [65]. In the ISAT, SB is questioned on week- and weekend days, as well as specific ST-related behaviours are questioned (i.e. TV/DVD viewing, computer/laptop/PlayStation use and smartphone/tablet use). The mean daily SB and ST of the fathers and their children will be calculated using the following formula: (SG or ST weekdays × 5 + SG or ST weekend days × 2) / 7.

Quality of the relationship between the father and the child will be measured with the Nurturant Fathering scale (NFS) [69]. This scale is a valid and reliable measure to characterize the relationship between the father and the child [70-72]. It consists of 9 items, each rated on a 5-point scale, and possible scores on this measure range from 9 to 45. Higher scores mean a better relationship.

The following determinants were questioned: (1) knowledge regarding the PA norm for both adults and (2) children, (3) knowledge and (4) self-efficacy towards motivating child for PA, (5) knowledge regarding limiting ST and (6) interrupting SB, (7) attitude towards limiting ST, (8) attitude towards and (9) importance of co-PA, (10) self-efficacy towards increasing co-PA, (11) degree of experienced barriers towards co-PA, (12) social support towards co-PA and (13) habits towards co-PA. For determinants on knowledge, participants were asked to estimate the norm (in minutes). The deviation from the norm was then calculated, with the value 0 representing a correct estimate of the norm and the higher the score deviating from 0, the greater the deviation from the correct answer. The other determinants were questioned and rated on a numerical response scale (values between 0 and 100, with 0 as the lowest score and 100 as the highest score).

The family context regarding PA will be questioned using the Family Health Climate Scale (FHC-PA) [68]. The family health climate can be seen as a determinant of person's health behaviour, and is defined as shared perceptions and cognitions concerning a healthy lifestyle within a family, and represents a family level variable that is intra- and inter-individually correlated to family environmental and individual factors. The FHC-PA is a validated questionnaire containing three subscales: value, cohesion and information on PA in the family. In total, this questionnaire contains 14 items, where participants can score these items on a 4-point Likert scale ranging from 1 "definitely false" to 4 "definitely true". The total score is the sum of all individual items scores, ranging from 14 to 56. Higher scores mean a better family health climate.

Parental skills and practices towards PA will be questioned in 16 questions, derived from four valid and reliable questionnaires each measuring specific parenting practices and skills [73-77].