Table 3.
Pooled energy expenditure data for the different types of activities undertaken during the study. Data are shown for each activity type. Sample size, mean (SD) of each of the measured device, mean (SD) of the difference between the device measurement and the reference standard, the mean relative difference (SD; %), the mean absolute difference (SD; %), and the correlation between the measures.
| Energy expenditure (kcal) and measures | Fitbit | Garmin | |||
| Max test (treadmill): progressive exercise to volitional fatigue | N=10 | N=6 | |||
|
|
Device, mean (SD) | 192.1 (47.2) | 216.5 (55.3) | ||
|
|
Criterion, mean (SD) | 237.3 (72.5) | 260.5 (77.2) | ||
|
|
Mean difference (SD) | −45.2 (44.4) | −44.0 (90.1) | ||
|
|
% mean relative error (SD) | −17.0 (14.6) | −11.4 (33.7) | ||
|
|
% mean absolute error (SD) | 19.4 (11.0) | 28.8 (17.2) | ||
|
|
Pearson correlation | .81 | .11 | ||
| Max test (ergometer): progressive exercise to volitional fatigue | N=10 | N=9 | |||
|
|
Device, mean (SD) | 133.6 (77.6) | 207.0 (48.7) | ||
|
|
Criterion, mean (SD) | 225.3 (74.7) | 231.4 (76.5) | ||
|
|
Mean difference (SD) | −91.7 (87.2) | −24.4 (63.9) | ||
|
|
% mean relative error (SD) | −39.1 (30.6) | −4.5 (25.3) | ||
|
|
% mean absolute error (SD) | 43.5 (23.0) | 18.9 (16.2) | ||
|
|
Pearson correlation | .35 | .56 | ||
| Resistance exercise | N=20 | N=16 | |||
|
|
Device, mean (SD) | 130.2 (46.2) | 179.8 (56.8) | ||
|
|
Criterion, mean (SD) | 153.1 (45.5) | 155.2 (47.8) | ||
|
|
Mean difference (SD) | −22.9 (44.0) | 24.6 (56.6) | ||
|
|
% mean relative error (SD) | −12.9 (29.7) | 21.0 (35.7) | ||
|
|
% mean absolute error (SD) | 27.7 (15.9) | 35.7 (19.7) | ||
|
|
Pearson correlation | .54 | .43 | ||
| Daily chores and activities of daily living | N=20 | N=18 | |||
|
|
Device, mean (SD) | 103.5 (38.2) | 100.6 (23.4) | ||
|
|
Criterion, mean (SD) | 114.4 (25.7) | 114.8 (27.0) | ||
|
|
Mean difference (SD) | −10.9 (39.4) | −14.3 (28.2) | ||
|
|
% mean relative error (SD) | −8.8 (29.2) | −10.6 (19.3) | ||
|
|
% mean absolute error (SD) | 20.9 (21.8) | 17.0 (13.7) | ||
|
|
Pearson correlation | .29 | .38 | ||
| Treadmill: intermittent high-intensity exercise | N=10 | N=9 | |||
|
|
Device, mean (SD) | 211.1 (57.0) | 226.9 (58.1) | ||
|
|
Criterion, mean (SD) | 246.6 (71.9) | 249.7 (75.6) | ||
|
|
Mean difference (SD) | −35.5 (34.6) | −22.8 (61.7) | ||
|
|
% mean relative error (SD) | −13.1 (12.7) | −4.7 (29.3) | ||
|
|
% mean absolute error (SD) | 14.5 (10.9) | 25.0 (3.4) | ||
|
|
Pearson correlation | .88 | .60 | ||
| Ergometer: intermittent high-intensity exercise | N=10 | N=9 | |||
|
|
Device, mean (SD) | 128.2 (60.4) | 205.8 (76.4) | ||
|
|
Criterion, mean (SD) | 232.8 (44.2) | 234.9 (46.4) | ||
|
|
Mean difference (SD) | −104.6 (83.8) | −29.1 (80.2) | ||
|
|
% mean relative error (SD) | −41.9 (1.3) | −11.2 (30.8) | ||
|
|
% mean absolute error (SD) | 41.9 (31.3) | 26.7 (17.0) | ||
|
|
Pearson correlation | –.26 | .22 | ||