Prospective relationships between body weight and physical activity: an observational analysis from the NAVIGATOR study.
OBJECTIVE
While bidirectional relationships exist between body weight and physical activity, direction of causality remains uncertain and previous studies have been limited by self-reported activity or weight and small sample size. We investigated the prospective relationships between weight and physical activity.


METHODS
Observational analysis of data from the Nateglinide And Valsartan in Impaired Glucose Tolerance Outcomes Research (NAVIGATOR) study, a double-blinded randomised clinical trial of nateglinide and valsartan, respectively.


METHODS
Multinational study of 9306 participants.


METHODS
Participants with biochemically confirmed impaired glucose tolerance had annual measurements of both weight and step count using research grade pedometers, worn for 7 days consecutively. Along with randomisation to valsartan or placebo plus nateglinide or placebo, participants took part in a lifestyle modification programme.


METHODS
Longitudinal regression using weight as response value and physical activity as predictor value was conducted, adjusted for baseline covariates. Analysis was then repeated with physical activity as response value and weight as predictor value. Only participants with a response value preceded by at least three annual response values were included.


RESULTS
Adequate data were available for 2811 (30%) of NAVIGATOR participants. Previous weight (χ(2)=16.8; p<0.0001), but not change in weight (χ(2)=0.1; p=0.71) was inversely associated with subsequent step count, indicating lower subsequent levels of physical activity in heavier individuals. Change in step count (χ(2)=5.9; p=0.02) but not previous step count (χ(2)=0.9; p=0.34) was inversely associated with subsequent weight. However, in the context of trajectories already established for weight (χ(2) for previous weight measurements 747.3; p<0.0001) and physical activity (χ(2) for previous step count 432.6; p<0.0001), these effects were of limited clinical importance.


CONCLUSIONS
While a prospective bidirectional relationship was observed between weight and physical activity, the magnitude of any effect was very small in the context of natural trajectories already established for these variables.


BACKGROUND
NCT00097786.
BHF Glasgow Cardiovascular Research Centre, University of Glasgow, Glasgow, UK.
David
D
Preiss
Duke Clinical Research Institute (DCRI), Duke University Medical Center, Durham, North Carolina, USA.
Laine E
LE
Thomas
Duke Clinical Research Institute (DCRI), Duke University Medical Center, Durham, North Carolina, USA.
Daniel M
DM
Wojdyla
Department of Medicine, Baylor College of Medicine, Houston, Texas, USA.
Steven M
SM
Haffner
BHF Glasgow Cardiovascular Research Centre, University of Glasgow, Glasgow, UK.
Jason M R
JM
Gill
Diabetes Research Centre, University of Leicester, Leicester, UK.
Thomas
T
Yates
Diabetes Research Centre, University of Leicester, Leicester, UK.
Melanie J
MJ
Davies
Diabetes Trials Unit, University of Oxford, Oxford, UK.
Rury R
RR
Holman
BHF Glasgow Cardiovascular Research Centre, University of Glasgow, Glasgow, UK.
John J
JJ
McMurray
Duke Translational Medicine Institute, Duke University Medical Center, Durham, North Carolina, USA.
Robert M
RM
Califf
Division of Cardiovascular Medicine, Duke University Medical Center, Durham, North Carolina, USA.
William E
WE
Kraus
D006801:Humans; D001835:Body Weight; D003510:Cyclohexanes / Q000627:therapeutic use; D004311:Double-Blind Method; D018149:Glucose Intolerance / Q000188:drug therapy / Q000503:physiopathology; D007004:Hypoglycemic Agents / Q000627:therapeutic use; D008019:Life Style; D009043:Motor Activity; D000077715:Nateglinide; D010649:Phenylalanine / Q000031:analogs & derivatives / Q000627:therapeutic use; D011446:Prospective Studies; D000068756:Valsartan / Q000627:therapeutic use; D016032:Randomized Controlled Trials as Topic; D015337:Multicenter Studies as Topic
D003510:Cyclohexanes; D007004:Hypoglycemic Agents; D000077715:Nateglinide; D010649:Phenylalanine; D000068756:Valsartan
EPIDEMIOLOGY; Nutrition < TROPICAL MEDICINE