Can quantifying the relative intensity of a person's free-living physical activity predict how they respond to a physical activity intervention? Findings from the PACES RCT.
Study Goal
The researchers aimed to determine if quantifying both absolute and relative intensity of accelerometer-assessed physical activity (PA) could inform PA interventions, hypothesizing that individuals with low relative intensity PA would be more likely to increase PA in response to an intervention.
Results Summary
The study found that low relative intensity of PA at baseline was associated with increased absolute PA intensity post-intervention, while high relative intensity was associated with decreased absolute intensity. The intervention did not improve overall PA volume.
Population
239 participants (86% male, average age 66.4) who had experienced cardiac events.
Effective Dosage
Not specified
Duration
12 months
Interactions
None mentioned
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
Physical Activity after Cardiac EventS intervention | no change | physical activity | participants (N=239, 86% male; age 66.4 (9.7)) | no significant change | showed no improvement | #1 |
- | increase | PA volume | participants at baseline | r=0.50, p<0.001 | was positively correlated | #2 |
- | increase | absolute intensity | participants at baseline | r=0.50, p<0.001 | was positively correlated | #3 |
- | decrease | relative intensity | participants at baseline | r=-0.13, p=0.025 | was negatively correlated | #4 |
Physical Activity after Cardiac EventS intervention | neutral | absolute intensity of PA | participants with low relative intensity at baseline | p=0.017 | moderated the change | #5 |
Physical Activity after Cardiac EventS intervention | increase | absolute intensity gradient | participants with low relative intensity at baseline | +0.5 SD | was associated with increased | #6 |
Physical Activity after Cardiac EventS intervention | decrease | absolute intensity gradient | participants with high relative intensity at baseline | -0.5 SD | was associated with decreased | #7 |
Physical Activity after Cardiac EventS intervention | increase | absolute PA intensity gradient | those with low relative intensity of PA | - | were more likely to increase | #8 |
OBJECTIVES: To determine whether quantifying both the absolute and relative intensity of accelerometer-assessed physical activity (PA) can inform PA interventions. We hypothesised that individuals whose free-living PA is at a low relative intensity are more likely to increase PA in response to an intervention, as they have spare physical capacity. METHOD: We conducted a secondary data analysis of a 12-month randomised controlled trial, Physical Activity after Cardiac EventS, which was designed to increase PA but showed no improvement. Participants (N=239, 86% male; age 66.4 (9.7); control N=126, intervention N=113) wore accelerometers for 7 days and performed the incremental shuttle walk test (ISWT) at baseline and 12 months. PA intensity was expressed in absolute terms (intensity gradient) and relative to acceleration at maximal physical capacity (predicted from an individual's maximal ISWT walking speed). PA outcomes were volume and absolute intensity gradient. RESULTS: At baseline, ISWT performance was positively correlated with PA volume (r=0.50, p<0.001) and absolute intensity (r=0.50, p<0.001), but negatively correlated with relative intensity (r=-0.13, p=0.025). Relative intensity of PA at baseline moderated the change in absolute intensity (p=0.017), but not volume, of PA postintervention. Low relative intensity at baseline was associated with increased absolute intensity gradient (+0.5 SD), while high relative intensity at baseline was associated with decreased absolute intensity gradient (-0.5 SD). CONCLUSION: Those with low relative intensity of PA were more likely to increase their absolute PA intensity gradient in response to an intervention. Quantifying absolute and relative PA intensity of PA could improve enables personalisation of interventions.