Cited by 418Physical Activity and HealthObesity, Physical Activity, DietChildren's Physical and Motor Development

Timing of the decline in physical activity in childhood and adolescence: gateshead millennium cohort study

Open access
Farooq, Mohammed Abdulaziz, Parkinson, Kathryn N, Adamson, Ashley J, Pearce, Mark S, Reilly, Jessica K, Hughes, Adrienne R, Janssen, Xanne, Basterfield, Laura +1 more·2018·British Journal of Sports Medicine

Abstract

Background and aim: There is a widely held and influential view that physical activity begins to decline at adolescence. This study aimed to identify the timing of changes in physical activity during childhood and adolescence. Methods: Longitudinal cohort study (Gateshead Millennium Study) with 8 years of follow-up, from North-East England. Cohort members comprise a socioeconomically representative sample studied at ages 7, 9, 12 and 15 years; 545 individuals provided physical activity data at two or more time points. Habitual total volume of physical activity and moderate-to-vigorous intensity physical activity (MVPA) were quantified objectively using the Actigraph accelerometer over 5–7 days at the four time points. Linear mixed models identified the timing of changes in physical activity across the 8-year period, and trajectory analysis was used to identify subgroups with distinct patterns of age-related changes. Results: Four trajectories of change in total volume of physical activity were identified representing 100% of all participants: all trajectories declined from age 7 years. There was no evidence that physical activity decline began at adolescence, or that adolescent declines in physical activity were substantially greater than the declines during childhood, or greater in girls than boys. One group (19% of boys) had relatively high MVPA which remained stable between ages 7 and15 years. Conclusions: Future policy and research efforts to promote physical activity should begin well before adolescence, and should include both boys and girls.

AI snapshot

Written from the paper’s full text.

TL;DR

In the Gateshead Millennium Study, objectively measured physical activity was already declining by age 7 years in both boys and girls, with no evidence that the decline began or accelerated specifically at adolescence. The findings challenge the orthodox focus on adolescent girls as the main high-risk group for low physical activity.

Key findings

  • Total physical activity declined from age 7 years in all identified trajectories: boys had three distinct trajectories and girls had one, together representing 100% of participants; no trajectory showed high childhood levels followed by a sharp adolescent decline.
  • Mean total physical activity fell from 780 cpm at age 7 to 482 cpm at age 15 in boys, and from 746 cpm to 400 cpm in girls; MVPA fell from 75.5 to 51.4 min/day in boys and from 63.4 to 41.0 min/day in girls.
  • MVPA trajectories were more complex: in boys, 3% had low and relatively stable/slowly declining MVPA, 17% had initially high but rapidly declining MVPA, 61% declined gradually, and 19% had relatively high and stable or increasing MVPA; in girls, 19% had low and relatively stable/modest declines, 62% declined gradually, and 19% had high initial MVPA with steeper declines.
  • There was no evidence that physical activity decline began at adolescence, was substantially greater during adolescence than childhood, or was greater in girls than boys.

Methods

  • Longitudinal cohort study (Gateshead Millennium Study) in North-East England, with follow-up at ages 7, 9, 12 and 15 years; 545 individuals provided physical activity data at two or more time points, and 217 at all four time points.
  • Habitual total physical activity and MVPA were measured objectively with Actigraph GT1M accelerometers over 5–7 days at each time point; MVPA used a cut-point of 574 counts per 15 s, with a +9% correction applied to raw data, and age-15 data adjusted for season.
  • Linear mixed models in SPSS described age-related changes; group-based trajectory modelling in STATA (Traj module) identified distinct trajectories, modelled separately for boys and girls using BIC and posterior probabilities.

Limitations

  • The paper states that generalisability may be limited to populations with substantially different physical, social and/or policy environments; it also states that why changes occur was beyond scope, direct biological measures such as pubertal maturation were unavailable, the 3% boys subgroup needs confirmation in other populations, and measurement timing was largely determined by funding availability.
  • Evident from the text: sample size declined across time points (431 at age 7 to 278 at age 15), and accelerometry excluded water-based activities, so some activity may be unmeasured.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1136/bjsports-2016-096933

Cites

31 of 31 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 24 cited sources checked · 0 supported · 0 flagged

  • Findingown data

    There was no evidence that adolescent declines in physical activity were greater in girls than boys.

    “There was no evidence that physical activity decline began at adolescence, or that adolescent declines in physical activity were substantially greater than the declines during childhood, or greater in girls than boys.”
    Quote in the paperSubstantial claim
  • Findingown data

    None of the trajectories of MVPA in either boys or girls were characterised by high and stable childhood values followed by sharp adolescent declines.

    “None of the trajectories of MVPA in either boys or girls were characterised by high and stable childhood values followed by sharp adolescent declines.”
    Quote in the paperSubstantial claim
  • Findingown data

    In boys, four distinct MVPA trajectories were identified.

    “In boys, four distinct subgroups were identified: low and relatively stable/slowly declining MVPA from age 7 years across the 8 years (3% of the sample); initially high at age 7 years, but rapidly declining from age 7 years (17% of the sample); gradually declining from age 7 years (61% of the sample); relatively high and stable or increasing from age 7 years (19% of the sample).”
    Quote in the paperSubstantial claim
  • Findingown data

    Four trajectories of change in total volume of physical activity were identified, representing 100% of all participants.

    “Four trajectories of change in total volume of physical activity were identified representing 100% of all participants: all trajectories declined from age 7 years.”
    Quote in the paperSubstantial claim
  • Findingown data

    One group (19% of boys) had relatively high MVPA which remained stable between ages 7 and 15 years.

    “One group (19% of boys) had relatively high MVPA which remained stable between ages 7 and15 years.”
    • Also stated in: § Main study findings and implications · hedged
      “in around 19% of boys MVPA was relatively high and fairly stable across the 8-year period.”
    Quote in the paperNot a substantial claim
  • May combine two claims. 10
  • Classified as probably not a substantial claim. 11
  • May combine two claims.

    Interpretationown data

    The study's findings are inconsistent with the orthodox view that physical activity begins to decline at adolescence, declines much more rapidly at adolescence, and/or declines much more rapidly in adolescent girls than boys.

    “The present study found that 100% of boys and girls fitted into longitudinal trajectories which were inconsistent with the orthodox view that physical activity begins to decline at adolescence, declines much more rapidly at adolescence and/or declines much more rapidly in adolescent girls than boys.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing).

    Interpretationnone given

    The findings may not be generalisable to populations with substantially different physical, social and/or policy environments.

    “One weakness may be generalisability to populations with substantially different physical, social and/or policy environments.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    The study used high quality objective measures of physical activity.

    “The main strengths of the present study were the longitudinal design, the high quality objective measures of physical activity, the socioeconomically representative sample and the contemporary nature of the cohort.”
    Quote in the paperNot a substantial claim
  • Classified as probably not a substantial claim.

    Study design and conductreasoning

    The study had a longitudinal design.

    “The main strengths of the present study were the longitudinal design, the high quality objective measures of physical activity, the socioeconomically representative sample and the contemporary nature of the cohort.”
    Quote in the paperSubstantial claim
  • Classified as probably not a substantial claim.

    Interpretationown data

    The study questions the concept of the adolescent girl as a priority for research and policy effort in physical activity.

    “The study questions the concept of the adolescent girl as a priority for research and policy effort in physical activity.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Study design and conductcitation

    The Actigraph accelerometer has high validity, high reliability and low reactivity in children.

    “The Actigraph is a small, unobtrusive and lightweight monitor with high validity (relative to reference measures of physical activity, direct observation and energy expenditure), high reliability and low reactivity in children,16”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [16] source

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Premisecitation

    The International Children's Accelerometry Database, though cross-sectional, suggests that objectively measured physical activity may be in decline in both sexes from around the age of school entry.

    “The International Children’s Accelerometry Database, though cross-sectional, suggests that objectively measured physical activity may be in decline in both sexes from around the age of school entry.13”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [13] Cooper, 2015, Objectively measured physical activity and sedentary time in youth: the International children’s accelerometry database (ICAD), Int J Behav Nutr Phys Act source

      Not checked in the free run.

  • May combine two claims.

    Premisereasoning

    Most studies in Dumith et al completed data collection before 2000 and probably lack generalisability to contemporary populations.

    “since most studies completed data collection before 2000, they probably lack generalisability to contemporary populations given recent and dramatic societal changes: declines in active commuting,10 in the technology being used by children10 (eg, the ubiquitous nature of new screen-based media),11 and in overweight and obesity (which appear to reduce physical activity).12”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [10] source

      Not checked in the free run.

    • cites [11] Christakis, 2014, Interactive media use at younger than the age of 2 years: time to rethink the American Academy of Pediatrics guideline?, JAMA Pediatr source

      Not checked in the free run.

    • cites [12] source

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Premisecitation

    In children born in Iowa in the early 1990s, physical activity declined, in both sexes, from age 5 years in most study participants.

    “in children born in Iowa in the early 1990s physical activity declined, in both sexes, from age 5 years in most study participants.14”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [14] Kwon, 2015, Developmental trajectories of physical activity, sports, and television viewing during childhood to young adulthood: Iowa bone development study, JAMA Pediatr source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Recent English longitudinal studies using objective measures are consistent with the present study in suggesting that physical activity does not decline especially markedly at adolescence, and does not decline more markedly in girls than boys during adolescence.

    “In summary, recent English longitudinal studies which used objective measures of physical activity are consistent with the present study in suggesting that physical activity does not decline especially markedly at adolescence, and does not decline more markedly in girls than boys during adolescence.”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [31] Harding, 2015, Longitudinal changes in sedentary time and physical activity during adolescence, Int J Behav Nutr Phys Act source

      Not checked in the free run.

    • cites [32] source

      Not checked in the free run.

    • cites [6] source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductown data

    Girls with more than two missing/invalid data points had slightly higher BMI z-scores at baseline than those with complete data, but similar physical activity.

    “Girls with more than two missing/invalid data points had slightly higher BMI z-scores at baseline than those with complete data, but similar physical activity.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    In the Avon Longitudinal Study of Parents and Children cohort, the incidence of obesity across childhood and adolescence peaked around age 7 years, and among non-obese individuals the rate of excessive weight gain also peaked at the same time.

    “In the Avon Longitudinal Study of Parents and Children cohort in England for example the incidence (appearance of new cases) of obesity across childhood and adolescence peaked around age 7 years,34 and among non-obese individuals the rate of excessive weight gain also peaked at the same time.35”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [34] source

      Not checked in the free run.

    • cites [35] source

      Not checked in the free run.

  • May combine two claims.

    Study design and conductown data

    Participants who provided data at least twice had similar physical activity and similar BMI-z scores at baseline compared with those who had missing or invalid accelerometer data.

    “Participants who provided data at least twice had similar physical activity and similar BMI-z scores at baseline compared with those who had missing or invalid accelerometer data.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    The cohort was contemporary.

    “The main strengths of the present study were the longitudinal design, the high quality objective measures of physical activity, the socioeconomically representative sample and the contemporary nature of the cohort.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Premisecitation

    Dumith et al's systematic review of changes in physical activity during adolescence included 26 eligible longitudinal studies, of which only 2/26 included objective measures of intensity, most (16/26) were from the USA, and representativeness was usually unclear.

    “Dumith et al 9 published the most recent systematic review of changes in physical activity during adolescence, with 26 eligible longitudinal studies. Of these eligible studies only 2/26 included objective measures of the intensity of physical activity (accelerometry), most (16/26) were from the USA, and the representativeness of the samples in the eligible studies was usually unclear.9”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [9] source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Tanaka et al found that accelerometer-measured daily sedentary time increased from around the age of school entry, and as sedentary time increased with age physical activity was displaced.

    “The recent systematic review by Tanaka et al also found that accelerometer-measured daily sedentary time increased from around the age of school entry, and as sedentary time increased with age physical activity was displaced.36”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [36] Tanaka, 2014, Longitudinal changes in objectively measured sedentary behaviour and their relationship with adiposity in children and adolescents: systematic review and evidence appraisal, Obes Rev source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S1 (asserted). May combine two claims.

    Premisecitation

    There is a widely held and influential view that physical activity begins to decline at adolescence, with the decline being much more marked in girls than boys.

    “There is a widely held and influential view that physical activity begins to decline at adolescence.”
    • Also stated in: § Introduction · boosted
      “For many years the prevailing view among researchers, policy makers, and health and education practitioners, based largely on subjective measurement of physical activity, has been that levels of physical activity are adequate during childhood, but decline dramatically during adolescence, with the adolescent decline being much more marked in girls than boys.3–6”
    Quote in the paperNot a substantial claim0 of 4 sources checked
    • cites [3] Physical Activity Review Group. Five year review of ’Let’s make Scotland more active: a strategy for physical activity': Update statement from the review group. Edinburgh: NHS Health Scotland, 2010.

      Not checked in the free run.

    • cites [4] Sportscotland. Increasing demand for sport and physical activity for adolescent girls in Scotland: Exploring issues and suggesting solutions. Edinburgh: sportscotland, 2006.

      Not checked in the free run.

    • cites [5] Activity P , Alliance H . Physical activity and adolescent girls – Knowledge Exchange Network. 2009. http://www.paha.org.uk/Feature/physical-activity-and-adolescent-girls-knowledge-exchange-network (accessed Jul 2016).

      Not checked in the free run.

    • cites [6] source

      Not checked in the free run.

17 of 17
  • The paper relies on this without support.

    The Gateshead Millennium Study cohort is representative of the UK population.

    “the sample was socioeconomically representative of the north-east of England.15”
    “The present study suggests that total volume of physical activity is already declining by age 7 years in the UK.”
1 of 1

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Boys' age-15 BMI z-score is marked as higher than at age 12

    Minor

    The table gives boys' mean BMI z-scores as 0.7 at age 12 and 0.5 at age 15. The § marker on the age-15 value says it is significantly higher than the age-12 value, although it is lower.

  • Girls' age-12 activity is marked as higher than itself

    Minor

    The § marker is attached to girls' total physical activity at age 12, but the table note defines § as significantly higher than at age 12. That comparison is with the same measurement.

2 of 2

Cites

Flagged first, then by citations

Research works printed but not linked: 1

  1. Physical Activity Review Group. Five year review of ’Let’s make Scotland more active: a strategy for physical activity': Update statement from the review group. Edinburgh: NHS Health Scotland, 2010.

Cited by

Sorted by citations

Authors
Farooq, M. A., Parkinson, K. N., Adamson, A. J., Pearce, M. S., Reilly, J. K., Hughes, A. R., Janssen, X., Basterfield, L., & Reilly, J. J.
Affiliations
  • University of Strathclyde (GB)
  • Newcastle University (GB)
Corresponding author
Reilly, John J
Venue
British Journal of Sports Medicine
Publisher
BMJ
Published
2017-03-13
Volume
52
Issue
15
Pages
1002-1006
ISSN
  • 0306-3674 (ISSN-L)
  • 1473-0480
OpenAlex
W2592553955
Cited by
418
References
31
Citations by year
2026: 23 · 2025: 33 · 2024: 41 · 2023: 43 · 2022: 67 · 2021: 66 · 2020: 63 · 2019: 44 · 2018: 27 · 2017: 11
FWCI
29.10
Type
journal article
Language
en
Open access
Licence
cc-by-nc
Locations
  • British Journal of Sports Medicine (publishedVersion, cc-by-nc)
  • Europe PMC (PubMed Central) (publishedVersion, other-oa)
  • PubMed Central (publishedVersion, cc-by-nc)
  • PubMed (publishedVersion)
  • Strathprints: The University of Strathclyde institutional repository (University of Strathclyde) (submittedVersion)
  • HighWire Press Open Archive (submittedVersion)
  • Newcastle University ePrints (Newcastle Univesity) (cc-by-nc)
Funders
  • UK Medical Research Council
  • Chief Scientist Office
Topics
  • Health Sciences › Medicine › Physiology › Physical Activity and Health
  • Health Sciences › Medicine › Public Health, Environmental and Occupational Health › Obesity, Physical Activity, Diet
  • Social Sciences › Psychology › Developmental and Educational Psychology › Children's Physical and Motor Development
Keywords
physical activity decline, children's physical activity, adolescent physical activity, moderate-to-vigorous physical activity, physical activity trajectories, sex differences in physical activity, accelerometer-measured activity
MeSH terms
Adolescent, Child, England, Female, Humans, Longitudinal Studies, Male, Time Factors, Exercise, Actigraphy, Sedentary Behavior

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-08.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-08.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

Are you an author, or do you see a problem with this page? Request a review