Feasibility of standing in older adult diabetics
There were no screen failures and no study drop-outs. All participants that were initially screened and included in the study completed all three sessions without any missing data. Sitting (baseline) sessions lasted on average 180.5±0.8 minutes, while static and dynamic were on average 240.5±0.9 and 240.4±0.7 minutes long, respectively.
Primary outcome measure: Oxygen Consumption
A significant effect of condition was found for VO2 consumption (F2,22=40.862, p<0.001, partial η²=0.788). In comparison to sitting, VO2 significantly increased by 28.0% (p<0.001) and 34.5% (p<0.001) during static and dynamic standing, respectively. Furthermore, there was a non-significant trend between both standing conditions, where dynamic standing was found to be 5.3% (p=0.052) higher VO2 intake (see table 3).
Secondary outcome measures: Net standing duration, rate of musculoskeletal discomfort development, leg swelling and cognition
Table 2 provides the summary descriptive statistics of user behavior and experience of table use.
Table 2: Results of descriptive measures of user behavior and experience of table use (average ± standard deviation).
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Sitting
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Static standing
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Dynamic standing
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Number of breaks (N)
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0.7±0.8
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2.3±2.2*
|
2.0±2.2*
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Duration of breaks (min)
|
1.9±2.4
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17.3±29.3*
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15.3±28.5*#
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Overall movement (counts/min)
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26.3±12.5
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43.7±29.4$
|
60.4±31.8*#
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Rate of total musculoskeletal discomfort development (mm/min)
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0.02±0.04
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0.39±0.53*
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0.23±0.37*#
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Average swelling for both legs (cm)
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0.11±0.17
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0.64±0.61*
|
0.44±0.48$
|
Note: Main effects are reported in the result section, however, post hoc tests are represented as follows: different from Sitting: *p < 0.05 ($ trend <0.10); different from Static standing: #p < 0.05 († trend <0.10).
Number and duration of breaks taken during sitting and standing conditions
As expected, patients took more breaks during both standing conditions as compared to sitting (χ2(2)=13.923, p=0.001). Post hoc testing revealed a significant increase in the number of break periods from sitting (median = 1 break) to static standing (Z=-2.536, p=0.011) as well as from sitting to dynamic standing (Z=-2.410, p=0.016), while static (median = 3 breaks) and dynamic (median = 2 breaks) standing did not differ (Z=-1.633, p=0.102) in the number of breaks taken. Breaks during sitting represented mainly restroom use while breaks during the standing conditions represented both restroom breaks as well as short duration of sitting. The total duration (in minutes) spent on breaks significantly differed between the three conditions (χ2(2)=13.027, p=0.001). Post hoc test revealed a significant increase of duration of breaks from sitting (median = 3 minutes) to static (median = 8 minutes) standing (Z=-2.807, p=0.005) as well as from sitting to dynamic (median = 6 minutes) standing condition (Z=-2.320, p=0.020). Duration of break periods was longer during static as compared to dynamic standing sessions (Z=-2.252, p=0.024).
Total movements
Overall movements, measured as total activity counts, progressively increased from sitting to static and dynamic standing (F2,22=40.862, p=0.001, partial η²=0.461). In comparison to sitting, total amount of activity counts also significantly increased by 182.2% (p=0.003) during dynamic standing. When comparing sitting to static standing, there was a near-significant increase of 113.7% of total movement (p=0.056). Dynamic standing activity counts increased by 65% compared to the static standing session (p=0.024).
Musculoskeletal discomfort rates
Figure 1 depicts average discomfort ratings over time for each of the sessions (sitting, static and dynamic standing), as well as their linear approximations of discomfort development rate.
The rate of total musculoskeletal discomfort development (mm/min) significantly differed between the three conditions (χ2(2)=10.889, p=0.004), with significant increases from sitting to static standing (Z=-2.201, p=0.028) and from sitting to dynamic standing (Z=-2.366, p=0.018). Finally, the dynamic standing condition (Z=-2.028, p=0.043) showed a lower rate of total musculoskeletal discomfort development when compared to the static standing condition.
Leg swelling
Overall leg swelling was low (less than 1 cm for all conditions), however, it significantly differed between the three conditions (χ2(2)=7.588, p=0.023). Compared to sitting, leg swelling was significantly higher for static standing (Z=-2.539, p=0.011) and non-significantly higher for dynamic standing (Z=-1.758, p=0.074). There was no difference in leg swelling between static and dynamic standing (Z=-1.122, p=0.262).
Cognitive performance
Table 3 lists cognitive outcome measures during each session.
Table 3: Primary and secondary outcome measures of sitting as well as static and dynamic standing sessions (average ± standard deviation)
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Sitting
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Static standing
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Dynamic standing
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P condition (partial η2)
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Δ Static - Sitting
|
Δ Dynamic - Sitting
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Primary outcome:
|
|
|
|
|
|
|
Oxygen uptake VO2 (ml/min/kg)
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3.3±0.6
|
4.2±0.6*
|
4.4±0.6*†
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<0.001 (0.788)
|
0.87±0.47
|
1.08±0.49¥
|
Secondary outcome:
|
|
|
|
|
|
|
TMT1: Visual Scanning (sec)
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26.8±9.9
|
23.3±3.8
|
24.6±7.4
|
0.228
|
-3.47±8.18
|
-2.19±7.45
|
TMT2: Number Sequencing (sec)
|
43.6±10.9
|
32.9±11.7*
|
37.0±17.9
|
0.022 (0.293)
|
-10.71±11.58
|
-6.53±14.42
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TMT3: Letter Sequencing (sec)
|
42.6±13.2
|
34.9±9.2
|
36.1±15.5
|
0.055
|
-7.72±11.39
|
-6.55±11.25
|
TMT4: Number-Letter Switching (sec)
|
93.0±43.5
|
80.7±53.0
|
90.6±53.3
|
0.221
|
-12.28±17.54
|
-2.41±27.58
|
TMT5: Motor Speed (sec)
|
36.9±11.0
|
33.9±14.0
|
31.8±12.7*
|
0.022 (0.292)
|
-2.93±6.37
|
-5.09±6.38
|
Stroop1: Word naming/reading (sec)
|
54.8±7.3
|
51.6±7.9*
|
52.3±8.8$
|
0.032 (0.269)
|
-3.17±4.02
|
-2.42±4.08
|
Stroop2: Color naming (sec)
|
72.3±16.9
|
67.4±17.1*
|
68.0±15.8*
|
0.018 (0.306)
|
-4.83±6.51
|
-4.25±4.90
|
Stroop3: Verbal response inhibition (sec)
|
123.2±28.6
|
109.8±23.8*
|
114.2±33.6$
|
0.013 (0.328)
|
-13.42±9.55
|
-9.00±16.83
|
Stroop4: Inhibition/switching (sec)
|
142.6±30.8
|
123.1±25.6*
|
125.1±35.5*
|
0.001 (0.457)
|
-19.50±12.60
|
-17.50±20.98
|
Note: TMT Trail Making Test; Main effects are reported in the results section, however, post hoc tests are represented as follows: different from Sitting: *p < 0.05 ($ trend <0.10); different from Static standing: #p < 0.05 († trend <0.10)
There were no negative effects for cognitive measures of set shifting (TMT) or response inhibition (Stroop test) during the standing sessions compared to sitting. Exploratory analyses showed limited but significant beneficial effects of session condition for all Stroop sub-sets as well as TMT sub-tests TMT2 and TMT5 (Table 3).