1. How many steps per day are enough? For older adults
David Rowe
Physical Activity for Health Research Group
University of Strathclyde
(Symposium with Catrine Tudor-Locke, Greet Cardon, Ilse De Bourdeaudhuij)

2. Standard-setting Normative data Intervention effects
Range of typical steps for the population
Intervention effects
Reasonable expectations for change
Controlled studies (cadence-time conversions)
What step rate ≈ 3 METs?
Computed step count equivalents
Baseline steps + 30 min MVPA equivalent (from #3)
Daily step-MVPA minutes equivalance (“test equating”)
Regression, ROC curves
Steps/day differentiating health and unhealthy populations (“known groups” evidence)
Maximal separation, group significant differences

4. = = = =
(?)

5. Question 1 – daily steps and minutes of MVPA
Methods:
Two separate waves of data collection, in year old (n = 129) And in yr old (n = 94) men and women
Actigraph 7164 worn for 7 days, 1-min epochs
Minutes of MVPA determined using Freedson equation (> 1951 cts/min)
Data analysed as average daily steps/mins MVPA, and as individual days
Results were similar

6. Regression method Middle-aged:
Mins MVPA = *steps – [r = .61]
===========================================
Older:
Mins MVPA = *steps – [r = .70]
Combined:
Mins MVPA = *steps – [r = .67]
0 mins MVPA ≈ 4,000 steps
(+ 10 mins MVPA ≈ 2,400 steps)

7. Error in predicting MVPA from steps

8. Conclusion – steps/day and MVPA
Between 40 years and 90 years, daily steps are moderately-highly correlated with minutes of MVPA
Age does not add to or moderate the steps-MVPA relationship
In cross-sectional data, people who take more moderate-intensity PA also engage in more mins of PA below moderate intensity
The relationship between steps and minutes of MVPA appears to become stronger as we age
This requires confirmation in larger epidemiological data sets (e.g., NHANES)

9. Question 2 – cadence/walking intensity
Methods:
Two samples, of younger (n = 38; yr) and older (n = 30; yr) women
Controlled laboratory study of treadmill and overground walking
Data presented here are from treadmill trials
Speed, cadence, METs, heart rate
Three trials (slow, medium, fast) ranging from 1.5 to 4.2 mph

10. Speed-intensity (MET) relationship
Younger:
METs = *mph – [r = .68]
3 METs = 2.4 mph
===========================================
Older:
METs = *mph [r = .56]
3 METs = 1.9 mph

11. Cadence-intensity (MET) relationship
Younger:
METs = *steps/min – [r = .56]
3 METs = 102 steps/min
===========================================
Older:
METs = *steps/min – [r = .56]
3 METs = 95 steps/min

12. Speed-Cadence relationship

13. Speed-intensity (%MXHR) relationship

14. Speed and EE – prior research
Adapted from Martin, Rothstein, & Larish (1992) Effects of age and physical activity status on the speed-aerobic demand relationship of walking J. Appl. Physiol., 73(1),

15. Conclusion – cadence and intensity
Investigating the cadence/intensity relationship is complex
Speed/cadence varies with age (cadence higher in older age)
Treadmill vs. overground issue
Intensity (METs) higher for a given speed in OAs
But at a given cadence, speed is lower
Net effect appears to be a slightly higher intensity (METs) for a given cadence [maybe ...]
We should focus on “what cadence/intensity brings health benefits?”

16. But how should we interpret “moderate intensity?”
3 METs = higher relative intensity in older adults

17. Thank you!