3.1 Baseline characteristics
The baseline characteristics of 571 participants are summarized in Table 1. Out of the 15 diabetic patients, 14 (2.5%) reported taking medications for diabetes. Only 86 (16%) of the participants reported using hormone replacement therapy. In addition, 66 (12%) used over-the-counter products for menopausal symptoms. Smoking was uncommon; 58 (11%) reported being occasional or daily smokers, and 477 (89%) were never smokers or had stopped smoking.
TABLE 1. Baseline characteristics, mean and (standard deviation)
Age (years)
|
53.1 (4.0)
|
Height (cm)
|
166.1 (6.6)
|
Weight (kg)
|
71.9 (13.2)
|
BMI (kg/m2)
|
26.0 (4.6)
|
Total cholesterol
|
5.30 (0.88)
|
HDL-c
|
1.78 (0.41)
|
LDL-c
|
3.00 (0.77)
|
Triglycerides
|
1.14 (0.57)
|
SB †
|
59.7 (8.9)
|
Standing †
|
17.6 (5.9)
|
Light PA †
|
13.8 (3.9)
|
MVPA †
|
8.9 (2.9)
|
Breaks (number/day)
|
34.8 (9.6)
|
Steps (number/day)
|
7483 (2682)
|
Current smoker
|
40 (7.5)
|
Hypertension
|
102 (19.3)
|
Antihypertensive medication
|
104 (19.3)
|
Statin treatment
|
29 (5.4)
|
Use of anticoagulants
|
12 (12.2)
|
Diabetes
|
15 (2.8)
|
Insulin treatment
|
4 (0.7)
|
Oral diabetes medications
|
10 (1.9)
|
Hypothyroidism with medication
|
67 (12.3)
|
Use of HRT
|
86 (16.0)
|
n = 533-571
BMI: body mass index; HDL-c: high-density lipoprotein cholesterol; LDL-c: low-density lipoprotein cholesterol; SB: sedentary behaviour; PA: physical activity; MVPA: mean to vigorous physical activity; HRT: hormone replacement therapy
† Proportion of the total measurement time
In the baseline physical activity measurements, the mean amount of SB was 60% (SD 8.9%) of the total measurement time. From the total measured time, the participants spent 18% (SD 5.9%) standing, 14% (SD 3.9%) performing light PA, and 8.9% (SD 2.9%) performing MVPA in addition to the 60% of SB. On average, the participants took 7483 steps daily (SD 2682), and they had 35 (SD 9.6) breaks during sedentary behaviour (Table 1).
3.2 Linear regression analysis of physical activity types and lipids
According to the linear regression analysis, light physical activity was associated with the concentration of HDL-c (coefficient 0.019, p < 0.001) (Table 2). After the models were adjusted for BMI, hypothyroidism medication use and hormone replacement therapy (HRT), this association remained still significant (coefficient 0.011, p = 0.005). The light PA was inversely related to the concentration of triglycerides in the unadjusted model (coefficient -0.011, p = 0.012), but this association disappeared after the adjustments were made (coefficient -0.004, p = 0.40) (Table 2). MVPA was associated with HDL-c both in the unadjusted model (coefficient 0.033, p < 0.001) and adjusted models (coefficient 0.018, p = 0.001) (Table 2). In addition, MVPA was inversely associated with the triglyceride concentration (coefficient -0.017, p = 0.004), but this association disappeared after the model was adjusted for BMI, hypothyroidism medication use and HRT (coefficient -0.004, p = 0.49) (Table 2). The number of breaks in SB was also associated with the concentration of HDL-c both in the unadjusted (coefficient 0.010, p < 0.001) and adjusted models (coefficient 0.005, p = 0.007). Breaks were associated with the triglyceride concentration in the unadjusted model (coefficient -0.009, p < 0.001) and in the adjusted model (coefficient -0.004, p = 0.028) (Table 2). The number of daily steps was associated with the concentration of HDL-c both in the unadjusted (coefficient 0.037, p < 0.001) and in the adjusted models (coefficient 0.019, p = 0.002). Additionally, the number of daily steps was inversely associated with the triglyceride concentration in the unadjusted model (coefficient -0.024, p < 0.001), but this association disappeared after the model was adjusted for the BMI, hypothyroidism medication use and HRT (coefficient -0.008, p = 0.23) (Table 2).
The relationship between standing and LDL-c was significant in the unadjusted model (coefficient -0.014, p = 0.016) but not in the adjusted model (-0.011, p = 0.072) (Table 2). MVPA and light PA were associated with TC both in the unadjusted model (coefficient 0.033, p = 0.009 and coefficient 0.019, p = 0.045, respectively) and adjusted models (coefficient 0.035, p = 0.008 and coefficient 0.019, p = 0.050, respectively).
TABLE 2. Regression coefficients with their 95% confidence intervals (CIs) from the linear regression models predicting lipids
|
Unadjusted
|
Adjusted†
|
|
|
n
|
Coeff. (95% CI)
|
p
|
n
|
Coeff. (95% CI)
|
p
|
|
Laying down and sitting
|
s-cholesterol
|
506
|
-0.004 (-0.012 to 0.004)
|
0.34
|
501
|
-0.004 (-0.013 to 0.005)
|
0.34
|
HDL-c
|
568
|
-0.013 (-0.017 to -0.010)
|
<0.001
|
530
|
-0.006 (-0.010 to -0.003)
|
0.001
|
LDL-c
|
509
|
0.003 (-0.004 to 0.010)
|
0.43
|
504
|
-0.000 (-0.008 to 0.008)
|
0.99
|
Triglycerides
|
568
|
0.010 (0.006 to 0.013)
|
<0.001
|
530
|
0.003 (-0.000 to 0.007)
|
0.087
|
Standing upright
|
s-cholesterol
|
506
|
-0.007 (-0.020 to 0.005)
|
0.25
|
501
|
-0.009 (-0.022 to 0.005)
|
0.19
|
HDL-c
|
568
|
0.014 (0.009 to 0.020)
|
<0.001
|
530
|
0.004 (-0.002 to 0.009)
|
0.20
|
LDL-c
|
509
|
-0.014 (-0.025 to -0.003)
|
0.016
|
504
|
-0.011 (-0.023 to 0.001)
|
0.072
|
Triglycerides
|
568
|
-0.013 (-0.019 to -0.008)
|
<0.001
|
530
|
-0.005 (-0.011 to 0.001)
|
0.13
|
Light physical activity
|
s-cholesterol
|
506
|
0.019 (0.000 to 0.038)
|
0.045
|
501
|
0.019 (0.000 to 0.038)
|
0.050
|
HDL-c
|
568
|
0.019 (0.011 to 0.027)
|
<0.001
|
530
|
0.011 (0.003 to 0.019)
|
0.005
|
LDL-c
|
509
|
0.010 (-0.007 to 0.027)
|
0.24
|
504
|
0.013 (-0.004 to 0.030)
|
0.14
|
Triglycerides
|
568
|
-0.011 (-0.020 to -0.002)
|
0.012
|
530
|
-0.004 (-0.012 to 0.005)
|
0.40
|
MVPA
|
s-cholesterol
|
506
|
0.033 (0.008 to 0.058)
|
0.009
|
509
|
0.035 (0.009 to 0.061)
|
0.008
|
HDL-c
|
568
|
0.033 (0.022 to 0.044)
|
<0.001
|
530
|
0.018 (0.007 to 0.029)
|
0.001
|
LDL-c
|
509
|
0.011 (-0.012 to 0.034)
|
0.35
|
504
|
0.018 (-0.005 to 0.042)
|
0.12
|
Triglycerides
|
568
|
-0.017 (-0.029 to -0.005)
|
0.004
|
530
|
-0.004 (-0.016 to 0.007)
|
0.49
|
Number of breaks per day
|
s-cholesterol
|
506
|
0.007 (-0.000 to 0.015)
|
0.064
|
501
|
0.008 (-0.001 to 0.016)
|
0.055
|
HDL-c
|
568
|
0.010 (0.007 to 0.013)
|
<0.001
|
530
|
0.005 (0.001 to 0.008)
|
0.007
|
LDL-c
|
509
|
0.003 (-0.004 to 0.010)
|
0.44
|
504
|
0.006 (-0.002 to 0.013)
|
0.12
|
Triglycerides
|
568
|
-0.009 (-0.012 to -0.005)
|
<0.001
|
530
|
-0.004 (-0.008 to -0.000)
|
0.028
|
Number of steps (thousands) per day
|
s-cholesterol
|
506
|
0.018 (-0.009 to 0.046)
|
0.19
|
501
|
0.021 (-0.008 to 0.049)
|
0.16
|
HDL-c
|
568
|
0.037 (0.025 to 0.049)
|
<0.001
|
530
|
0.019 (0.007 to 0.031)
|
0.002
|
LDL-c
|
509
|
-0.003 (-0.027 to 0.022)
|
0.84
|
504
|
0.007 (-0.019 to 0.033)
|
0.58
|
Triglycerides
|
568
|
-0.024 (-0.037 to -0.012)
|
<0.001
|
530
|
-0.008 (-0.020 to 0.005)
|
0.23
|
HDL-c: high density lipoprotein cholesterol; LDL-c: low density lipoprotein cholesterol; Triglycerides: log-transformed triglyceride concentration; MVPA: moderate-to-vigorous physical activity
† Adjusted for BMI, hypothyroidism medication use, and hormone replacement therapy
In all analyses concerning s-cholesterol and LDL-c the participants using statin therapy were excluded
3.3 Association of lipids and sedentary behaviour
The mean HDL-c level was the highest (1.92 (SD 0.43) mmol/l) in the participants who had the least amount of SB (SB less than 54% of waking hours) (Table 3).
The triglyceride concentration was on average 0.25 mmol/l (p < 0.001) lower in the group with SB ≥ 66% than in the group of women with SB less than 54% (Figure 2). The differences between the groups disappeared after the adjustments were made to the model (Figure 2). Compared to the SB <54% group, the SB 54-65.9% group and SB ≥ 66% group had lower HDL-c concentrations by 0.12 mmol/l (p = 0.001) and 0.32 mmol/l (p < 0.001), respectively (Figure 2). The differences between the groups remained significant after the model was adjusted: the concentration of HDL-c was 0.08 mmol/l lower in the SB 54-65.9% group (p = 0.035) and 0.14 mmol/l lower in the SB ≥ 66% group (p = 0.003) than in the SB < 54% group (Figure 2).
TABLE 3. Serum lipid mean and standard deviations for the subgroups of participants grouped by the amounts of sedentary behaviour and moderate-to-vigorous physical activity performed
|
SB
|
|
|
MVPA
|
|
|
|
< 54%
|
54-65.9%
|
≥ 66%
|
< 6.8%
|
6.8-10.79%
|
≥ 10.8%
|
s-cholesterol
|
5.40 (0.93)
|
5.30 (0.88)
|
5.19 (0.80)
|
5.17 (0.88)
|
5.28 (0.83)
|
5.46 (0.95)
|
HDL-c
|
1.92 (0.43)
|
1.80 (0.39)
|
1.60 (0.36)
|
1.64 (0.39)
|
1.79 (0.40)
|
1.90 (0.39)
|
LDL-c
|
3.00 (0.78)
|
3.00 (0.80)
|
3.00 (0.68)
|
2.97 (0.78)
|
2.99 (0.72)
|
3.06 (0.84)
|
Triglycerides
|
1.02 (0.51)
|
1.11 (0.58)
|
1.32 (0.59)
|
1.26 (0.59)
|
1.12 (0.57)
|
1.07 (0.55)
|
SB: sedentary behaviour; MVPA: moderate-to-vigorous physical activity; HDL-c: high-density lipoprotein cholesterol; LDL-c: low-density lipoprotein cholesterol
3.4 Association of lipids and breaks during sedentary behaviour
When the number of daily breaks during SB were distributed to quartiles the mean concentration of HDL-c was the highest (1.89 mmol/l, SD 0.38), and the mean concentration of triglycerides was lowest (1.04 mmol/, SD 0.48) in the quartile with the most daily breaks (≥ 41) compared to the quartile with the lowest number of breaks (< 28).
In the unadjusted models, the HDL-c level was 0.16 mmol/l higher (p < 0.001) in the intermediate group (28-40.9 breaks) and 0.25 mmol/l higher (p < 0.001) in the group with the most breaks (≥ 41) than in the group with the fewest breaks during SB (< 28). After the model was adjusted for BMI, hypothyroidism medication use and HRT, the HDL-c level was 0.11 mmol/l higher (p = 0.017) in the group with ≥ 41 daily breaks during SB than in the group with < 28 breaks (Table 4).
The concentration of triglycerides was significantly lower both in the group with 28-40.9 breaks (-0.15 mmol/l, p = 0.001) and in the group with ≥ 41 breaks (-0.22 mmol/l, p < 0.001) than in the group with the fewest breaks (<28). The differences remained significant even after the adjustments were made; the concentration of triglycerides was -0.09 mmol/l lower (p = 0.031) in the group with 28-40.9 breaks and -0.10 mmol/l lower (p = 0.032) in the group with ≥ 41 breaks when compared to the group with the fewest breaks (< 28) (Table 4).
TABLE 4. Regression coefficients with their 95% confidence intervals (CIs) from the linear regression models predicting lipids by the number of breaks in a day (fewer than 28 breaks in a day used as the reference group).
|
Unadjusted
|
Adjusted†
|
|
Breaks 28-40.9 / day
|
Breaks 41+ / day
|
Breaks 28-40.9 / day
|
Breaks 41+ / day
|
|
Coeff. (95% CI)
|
p
|
Coeff. (95% CI)
|
p
|
Coeff. (95% CI)
|
p
|
Coeff. (95% CI)
|
p
|
s-cholesterol
|
0.10 (-0.08 to 0.28)
|
0.27
|
0.19 (-0.02 to 0.39)
|
0.070
|
0.10 (-0.08 to 0.29)
|
0.28
|
0.21 (-0.10 to 0.42)
|
0.062
|
HDL-c
|
0.16 (0.08 to 0.24)
|
<0.001
|
0.25 (0.16 to 0.34)
|
<0.001
|
0.06 (-0.02 to 0.14)
|
0.13
|
0.11 (0.02 to 0.20)
|
0.017
|
LDL-c
|
0.06 (-0.10 to 0.23)
|
0.44
|
0.09 (-0.10 to 0.27)
|
0.35
|
0.10 (-0.06 to 0.27)
|
0.23
|
0.16 (-0.03 to 0.36)
|
0.093
|
Triglycerides
|
-0.15 (-0.24 to -0.07)
|
0.001
|
-0.22 (-0.31 to -0.13)
|
<0.001
|
-0.09 (-0.17 to -0.01)
|
0.031
|
-0.10 (-0.20 to -0.01)
|
0.032
|
HDL: high-density lipoprotein; LDL: low-density lipoprotein; Triglycerides: log-transformed triglyceride concentration
† Adjusted for BMI, hypothyroidism medication use, and hormone replacement therapy
In analyses concerning s-cholesterol and LDL-c the participants using statin therapy were excluded
3.5 Association of lipids and daily steps
The mean number of steps per day for the whole study population was 7483 (SD 2682). In the group with the fewest steps (<5600 steps/day), the mean concentration of HDL-c was 1.63 (SD 0.36) mmol/l. In the intermediate group (5600-9099 steps/day), the mean HDL-c was 1.80 (SD 0.41) mmol/l. The group with the most daily steps (≥ 9100) had the highest mean HDL-c level, which was 1.90 (SD 0.41) mmol/l.
In the unadjusted models, the HDL-c level was 0.16 mmol/l higher (p < 0.001) in the 5600-9099 steps/day group and 0.26 mmol/l higher (p < 0.001) in the ≥ 9100 steps/day group than in the group with the fewest steps (< 5600). After the model was adjusted for BMI, hypothyroidism medication use, and HRT, the HDL-c level was 0.13 mmol/l higher (p = 0.006) in the ≥ 9100 steps/day group than in the < 5600 steps/day group (Table 5).
The concentration of triglycerides was significantly lower in the groups with 5600-9099 (-0.16 mmol/l, p < 0.001) and at least 9100 (-0.19 mmol/l, p < 0.001) daily steps than in the group with fewer than 5600 daily steps. These significant findings disappeared after the adjustments were made (Table 5).
TABLE 5. Regression coefficients with their 95% confidence intervals (CIs) from the linear regression models predicting lipids by the number of steps in day (fewer than 5600 steps in a day used as the reference group)
|
Unadjusted
|
Adjusted†
|
|
5600-9099 steps / day
|
≥ 9100 steps / day
|
5600-9099 steps / day
|
≥ 9100 steps / day
|
|
Coeff. (95% CI)
|
p
|
Coeff. (95% CI)
|
p
|
Coeff. (95% CI)
|
p
|
Coeff. (95% CI)
|
p
|
s-cholesterol
|
0.06 (-0.12 to 0.25)
|
0.49
|
0.16 (-0.05 to 0.37)
|
0.13
|
0.09 (-0.10 to 0.28)
|
0.37
|
0.18 (-0.04 to 0.40)
|
0.10
|
HDL-c
|
0.16 (0.08 to 0.24)
|
<0.001
|
0.26 (0.17 to 0.35)
|
<0.001
|
0.04 (-0.03 to 0.12)
|
0.26
|
0.13 (0.04 to 0.22)
|
0.006
|
LDL-c
|
0.01 (-0.15 to 0.18)
|
0.87
|
0.02 (-0.17 to 0.20)
|
0.85
|
0.08 (-0.08 to 0.25)
|
0.33
|
0.10 (-0.10 to 0.29)
|
0.32
|
Triglycerides
|
-0.16 (-0.24 to -0.07)
|
<0.001
|
-0.19 (-0.29 to -0.10)
|
<0.001
|
-0.07 (-0.15 to 0.10)
|
0.085
|
-0.08 (-0.17 to 0.02)
|
0.10
|
HDL-c: high-density lipoprotein; LDL-c: low-density lipoprotein; Triglycerides: log-transformed triglyceride concentration
† Adjusted for BMI, hypothyroidism medication use, and hormone replacement therapy
In analyses concerning s-cholesterol and LDL-c the participants using statin therapy were excluded
3.6 Association of lipids and MVPA
As expected, the mean HDL-c level was the highest in the quartile with the highest amount of MVPA (at least 10.8% of waking hours). In this group, the mean HDL-c level was 1.90 (SD 0.39) mmol/l (Table 3). In the unadjusted linear regression models, the HDL-c level was 0.14 mmol/l (p = 0.001) higher in the MVPA 6.8-10.79% group and 0.25 mmol/l (p < 0.001) higher in the MVPA ≥ 10.8% group than in the MVPA less than 6.8% group. After the adjustments were made, the concentration of HDL-c was 0.14 mmol/l (p = 0.002) higher in the MVPA ≥ 10.8% group than in the MVPA < 6.8% group. In the unadjusted models, the concentration of triglycerides was 0.12 mmol/l (p = 0.005) lower in the MVPA 6.8-10.79% group and 0.15 mmol/l (p = 0.002) lower in the MVPA ≥ 10.8% group than in the MVPA < 6.8% group (Table 6). All these significant differences disappeared after the adjustments were made (Table 6).
TABLE 6. Regression coefficients with their 95% confidence intervals (CIs) from the linear regression models predicting lipids by the amount of moderate-to-vigorous physical activity (MVPA; < 6.8% used as the reference group).
Unadjusted
|
Adjusted†
|
MVPA 6.8-10.79%
|
MVPA ≥ 10.8%
|
MVPA 6.8-10.79%
|
MVPA ≥ 10.8%
|
Coeff. (95% CI)
|
p
|
Coeff. (95% CI)
|
p
|
Coeff. (95% CI)
|
p
|
Coeff. (95% CI)
|
p
|
s-cholesterol
|
0.07 (-0.11 to 0.25)
|
0.42
|
0.25 (0.04 to 0.45)
|
0.019
|
0.10 (-0.09 to 0.28)
|
0.31
|
0.27 (0.05 to 0.48)
|
0.014
|
HDL-c
|
0.14 (0.06 to 0.22)
|
0.001
|
0.25 (0.16 to 0.34)
|
<0.001
|
0.05 (-0.03 to 0.12)
|
0.24
|
0.14 (0.05 to 0.23)
|
0.002
|
LDL-c
|
0.03 (-0.14 to 0.19)
|
0.74
|
0.06 (-0.12 to 0.25)
|
0.50
|
0.09 (-0.08 to 0.26)
|
0.30
|
0.13 (-0.06 to 0.32)
|
0.17
|
Triglycerides
|
-0.12 (-0.20 to -0.04)
|
0.005
|
-0.15 (-0.24 to -0.05)
|
0.002
|
-0.04 (-0.12 to 0.04)
|
0.35
|
-0.04 (-0.13 to 0.06)
|
0.43
|
HDL-c: high-density lipoprotein cholesterol; LDL-c: low-density lipoprotein cholesterol; Triglycerides: log-transformed triglyceride concentration
† Adjusted for BMI, hypothyroidism medication use, and hormone replacement therapy
In analyses concerning s-cholesterol and LDL-c the participants using statin therapy were excluded