Baseline characteristics of participants
A total of 12,061 individuals were included in this study, including 3,188 (26.43%) with MetS and 8,873 (73.57%) with non-MetS. Overall, there was a significant difference in the demographic characteristics of both MetS and non-MetS groups (p < 0.05). Out of the 3,188 MetS, 22.65% were male and 77.35% were female. Among non-MetS, 59.54% were male and 40.46% were female. The highest percentage of age groups in MetS is 45–64 years, reached 42.88%, and 20–44 years in non-MetS reached 47.26%. Compared to the non-MetS group, the MetS population had a far higher percentage of females and obese people, and a significantly lower percentage of young adults (20–44 years). Never smokers had the highest percentage in both MetS and non-MetS, 53.75% and 55.03%, respectively. Non-drinkers had the highest percentage in both MetS and non-MetS, 75.14% and 66.61%, respectively, and comparisons of the remaining relevant variables are shown in Table 1.
Table 1
Comparison of the baseline characteristics of participants with metabolic syndrome (MetS) and non-metabolic syndrome (non-MetS).
Variables | Total (n = 12061) | Non-MetS (n = 8873) | MetS (n = 3188) | p |
PA all, M (Q₁, Q₃) | 20.00 (0.00, 69.00) | 24.00 (4.00, 80.00) | 9.00 (0.00, 40.00) | < .001 |
Gender, n(%) | | | | < .001 |
Men | 6005 (49.79) | 5283 (59.54) | 722 (22.65) | |
Women | 6056 (50.21) | 3590 (40.46) | 2466 (77.35) | |
Age group, n(%) | | | | < .001 |
20–44 | 4943 (40.98) | 4193 (47.26) | 750 (23.53) | |
45–64 | 4252 (35.25) | 2885 (32.51) | 1367 (42.88) | |
≥ 65 | 2866 (23.76) | 1795 (20.23) | 1071 (33.59) | |
Race, n(%) | | | | < .001 |
Mexican American | 1787 (14.82) | 1276 (14.38) | 511 (16.03) | |
Non-Hispanic Black | 2359 (19.56) | 1771 (19.96) | 588 (18.44) | |
Non-Hispanic White | 5329 (44.18) | 3874 (43.66) | 1455 (45.64) | |
Other Hispanic | 1228 (10.18) | 874 (9.85) | 354 (11.10) | |
Other Race - Including Multi-Racial | 1358 (11.26) | 1078 (12.15) | 280 (8.78) | |
Education level, n(%) | | | | < .001 |
<High school | 2786 (23.10) | 1876 (21.14) | 910 (28.54) | |
High school graduate | 2758 (22.87) | 1956 (22.04) | 802 (25.16) | |
Some college | 3580 (29.68) | 2623 (29.56) | 957 (30.02) | |
College graduate or above | 2937 (24.35) | 2418 (27.25) | 519 (16.28) | |
Marital status, n(%) | | | | < .001 |
Married | 6259 (51.89) | 4635 (52.24) | 1624 (50.94) | |
Never married | 2144 (17.78) | 1804 (20.33) | 340 (10.66) | |
Living with partner | 999 (8.28) | 793 (8.94) | 206 (6.46) | |
Divorced | 1364 (11.31) | 897 (10.11) | 467 (14.65) | |
Separated | 405 (3.36) | 285 (3.21) | 120 (3.76) | |
Widowed | 890 (7.38) | 459 (5.17) | 431 (13.52) | |
PIR group, n(%) | | | | < .001 |
< 1.35 | 3959 (32.82) | 2746 (30.95) | 1213 (38.05) | |
1.35-3.00 | 3703 (30.70) | 2674 (30.14) | 1029 (32.28) | |
≥ 3.00 | 4399 (36.47) | 3453 (38.92) | 946 (29.67) | |
BMI group, n(%) | | | | < .001 |
Under 25 | 3507 (29.08) | 3228 (36.38) | 279 (8.75) | |
25–30.0 | 4028 (33.40) | 3076 (34.67) | 952 (29.86) | |
30.0 and over | 4526 (37.53) | 2569 (28.95) | 1957 (61.39) | |
Smoking, n(%) | | | | 0.016 |
Never smoker | 6591 (54.69) | 4878 (55.03) | 1713 (53.75) | |
Ex-smoker | 3031 (25.15) | 2171 (24.49) | 860 (26.98) | |
Current smoker | 2430 (20.16) | 1816 (20.49) | 614 (19.27) | |
Drinking, n(%) | | | | < .001 |
Non-drinker | 8300 (68.87) | 5906 (66.61) | 2394 (75.14) | |
Drinker | 3752 (31.13) | 2960 (33.39) | 792 (24.86) | |
Covered by health insurance, n(%) | | | | < .001 |
No | 2554 (21.18) | 1991 (22.44) | 563 (17.66) | |
Yes | 9507 (78.82) | 6882 (77.56) | 2625 (82.34) | |
Out of 12,061 participants, 2,162 (17.92%) were CircS and 9,899 (82.08%) were non-CircS. Overall, the demographic characteristics of the CircS and non-CircS groups were significantly different except for health insurance (P < 0.05). In CircS 17.07% were male and 82.93% were female. Non-CircS was 56.9% male and 43.06% female. The highest percentage of age group in CircS was 45–64 years reaching 44.82%, and 20–44 years in non-CircS reaching 44.65%. Compared to the non-CircS group, the CircS population had a far higher proportion of female, obese people, and a lower proportion of young adults (20–44 years). Never smokers had the highest percentage in both CircS and non-CircS, 51.64% and 55.35%, respectively. Non-drinkers had the highest percentage in both CircS and non-CircS, 75.93% and 67.33%, respectively, and comparisons of the remaining relevant variables are shown in Table 2.
Table 2
Comparison of the baseline characteristics of participants with circadian syndrome (CircS) and non-circadian syndrome (non-CircS).
Variables | Total (n = 12061) | Non-CircS (n = 9899) | CircS (n = 2162) | p |
PA all, M (Q₁, Q₃) | 20.00 (0.00, 69.00) | 24.00 (2.67, 76.00) | 8.00 (0.00, 37.25) | < .001 |
Gender, n(%) | | | | < .001 |
Men | 6005 (49.79) | 5636 (56.94) | 369 (17.07) | |
Women | 6056 (50.21) | 4263 (43.06) | 1793 (82.93) | |
Age group, n(%) | | | | < .001 |
20–44 | 4943 (40.98) | 4420 (44.65) | 523 (24.19) | |
45–64 | 4252 (35.25) | 3283 (33.16) | 969 (44.82) | |
≥ 65 | 2866 (23.76) | 2196 (22.18) | 670 (30.99) | |
Race, n(%) | | | | < .001 |
Mexican American | 1787 (14.82) | 1438 (14.53) | 349 (16.14) | |
Non-Hispanic Black | 2359 (19.56) | 1914 (19.34) | 445 (20.58) | |
Non-Hispanic White | 5329 (44.18) | 4385 (44.30) | 944 (43.66) | |
Other Hispanic | 1228 (10.18) | 978 (9.88) | 250 (11.56) | |
Other Race - Including Multi-Racial | 1358 (11.26) | 1184 (11.96) | 174 (8.05) | |
Education level, n(%) | | | | < .001 |
<High school | 2786 (23.10) | 2098 (21.19) | 688 (31.82) | |
High school graduate | 2758 (22.87) | 2204 (22.26) | 554 (25.62) | |
Some college | 3580 (29.68) | 2950 (29.80) | 630 (29.14) | |
College graduate or above | 2937 (24.35) | 2647 (26.74) | 290 (13.41) | |
Marital status, n(%) | | | | < .001 |
Married | 6259 (51.89) | 5263 (53.17) | 996 (46.07) | |
Never married | 2144 (17.78) | 1876 (18.95) | 268 (12.40) | |
Living with partner | 999 (8.28) | 869 (8.78) | 130 (6.01) | |
Divorced | 1364 (11.31) | 1023 (10.33) | 341 (15.77) | |
Separated | 405 (3.36) | 304 (3.07) | 101 (4.67) | |
Widowed | 890 (7.38) | 564 (5.70) | 326 (15.08) | |
PIR group, n(%) | | | | < .001 |
< 1.35 | 3959 (32.82) | 3013 (30.44) | 946 (43.76) | |
1.35-3.00 | 3703 (30.70) | 3030 (30.61) | 673 (31.13) | |
≥ 3.00 | 4399 (36.47) | 3856 (38.95) | 543 (25.12) | |
BMI group, n(%) | | | | < .001 |
Under 25 | 3507 (29.08) | 3328 (33.62) | 179 (8.28) | |
25–30.0 | 4028 (33.40) | 3419 (34.54) | 609 (28.17) | |
30.0 and over | 4526 (37.53) | 3152 (31.84) | 1374 (63.55) | |
Smoking, n(%) | | | | < .001 |
Never smoker | 6591 (54.69) | 5475 (55.35) | 1116 (51.64) | |
Ex-smoker | 3031 (25.15) | 2494 (25.21) | 537 (24.85) | |
Current smoker | 2430 (20.16) | 1922 (19.43) | 508 (23.51) | |
Drinking, n(%) | | | | < .001 |
Non-drinker | 8300 (68.87) | 6660 (67.33) | 1640 (75.93) | |
Drinker | 3752 (31.13) | 3232 (32.67) | 520 (24.07) | |
Covered by health insurance, n(%) | | | | 0.008 |
No | 2554 (21.18) | 2142 (21.64) | 412 (19.06) | |
Yes | 9507 (78.82) | 7757 (78.36) | 1750 (80.94) | |
Among 12,061 participants, 1,953 (16.19%) were MetS and CircS comorbidity, and the number of CircS not comorbid with MetS was 10,108 (83.81%). In comorbidity, males were 13.26% and females were 86.74%. Out of 10,108 participants of CircS not comorbid with MetS, males were 56.85% and females were 43.15%. The percentage of comorbidity reached a maximum of 44.55% in the age group 45–64 years and 44.38% in the age group 20–44 years in CircS not comorbid with MetS. BMI ≥ 30 in comorbidity accounted for 66.15% (Table 3).
Table 3
Comparison of the baseline characteristics of participants with MetS and CircS comorbidity.
Variables | Total (n = 12061) | No (n = 10108) | Yes (n = 1953) | Statistic | p | |
PA all, M (Q₁, Q₃) | 20.00 (0.00, 69.00) | 23.50 (2.67, 76.00) | 8.00 (0.00, 34.00) | Z=-16.41 | < .001 | |
Gender, n(%) | | | | χ²=1243.70 | < .001 | |
Men | 6005 (49.79) | 5746 (56.85) | 259 (13.26) | | | |
Women | 6056 (50.21) | 4362 (43.15) | 1694 (86.74) | | | |
Age group, n(%) | | | | χ²=300.29 | < .001 | |
20–44 | 4943 (40.98) | 4486 (44.38) | 457 (23.40) | | | |
45–64 | 4252 (35.25) | 3382 (33.46) | 870 (44.55) | | | |
≥ 65 | 2866 (23.76) | 2240 (22.16) | 626 (32.05) | | | |
Race, n(%) | | | | χ²=33.74 | < .001 | |
Mexican American | 1787 (14.82) | 1466 (14.50) | 321 (16.44) | | | |
Non-Hispanic Black | 2359 (19.56) | 1983 (19.62) | 376 (19.25) | | | |
Non-Hispanic White | 5329 (44.18) | 4460 (44.12) | 869 (44.50) | | | |
Other Hispanic | 1228 (10.18) | 996 (9.85) | 232 (11.88) | | | |
Other Race - Including Multi-Racial | 1358 (11.26) | 1203 (11.90) | 155 (7.94) | | | |
Education level, n(%) | | | | χ²=204.36 | < .001 | |
<High school | 2786 (23.10) | 2165 (21.42) | 621 (31.80) | | | |
High school graduate | 2758 (22.87) | 2260 (22.36) | 498 (25.50) | | | |
Some college | 3580 (29.68) | 3002 (29.70) | 578 (29.60) | | | |
College graduate or above | 2937 (24.35) | 2681 (26.52) | 256 (13.11) | | | |
Marital status, n(%) | | | | χ²=344.98 | < .001 | |
Married | 6259 (51.89) | 5351 (52.94) | 908 (46.49) | | | |
Never married | 2144 (17.78) | 1917 (18.97) | 227 (11.62) | | | |
Living with partner | 999 (8.28) | 881 (8.72) | 118 (6.04) | | | |
Divorced | 1364 (11.31) | 1054 (10.43) | 310 (15.87) | | | |
Separated | 405 (3.36) | 322 (3.19) | 83 (4.25) | | | |
Widowed | 890 (7.38) | 583 (5.77) | 307 (15.72) | | | |
PIR group, n(%) | | | | χ²=157.50 | < .001 | |
< 1.35 | 3959 (32.82) | 3111 (30.78) | 848 (43.42) | | | |
1.35-3.00 | 3703 (30.70) | 3095 (30.62) | 608 (31.13) | | | |
≥ 3.00 | 4399 (36.47) | 3902 (38.60) | 497 (25.45) | | | |
BMI group, n(%) | | | | χ²=931.85 | < .001 | |
Under 25 | 3507 (29.08) | 3372 (33.36) | 135 (6.91) | | | |
25–30.0 | 4028 (33.40) | 3502 (34.65) | 526 (26.93) | | | |
30.0 and over | 4526 (37.53) | 3234 (31.99) | 1292 (66.15) | | | |
Smoking, n(%) | | | | χ²=8.53 | 0.014 | |
Never smoker | 6591 (54.69) | 5571 (55.16) | 1020 (52.25) | | | |
Ex-smoker | 3031 (25.15) | 2537 (25.12) | 494 (25.31) | | | |
Current smoker | 2430 (20.16) | 1992 (19.72) | 438 (22.44) | | | |
Drinking, n(%) | | | | χ²=56.21 | < .001 | |
Non-drinker | 8300 (68.87) | 6816 (67.48) | 1484 (76.06) | | | |
Drinker | 3752 (31.13) | 3285 (32.52) | 467 (23.94) | | | |
Covered by health insurance, n(%) | | | | χ²=9.73 | 0.002 | |
No | 2554 (21.18) | 2192 (21.69) | 362 (18.54) | | | |
Yes | 9507 (78.82) | 7916 (78.31) | 1591 (81.46) | | | |
Z: Mann-Whitney test, χ²: Chi-square test |
M: Median, Q₁: 1st Quartile, Q₃: 3rd Quartile |
The relationship between physical activity and three diseases
The groupings were made in tertiles according to the amount of physical activity, with the first tertile as the reference group. The second and third tertiles in model 1 exhibited significant protection against MetS compared to the reference group (0.59 (0.54 ~ 0.65, p < 0.001; 0.40 (0.36 ~ 0.44), p < 0.001). This protection was further verified after adjusting for age, sex, race, and BMI (0.82 (0.73 ~ 0.92), p < 0.001; 0.85 (0.75 ~ 0.96, p < 0.009). After further adjusting for all covariates, only the protection of third tertile subgroup was ascertained (0.87 (0.77 ~ 0.99), p < 0.034).
Similarly, the significant protection against CircS in Model 1 was observed in the second and third tertile subgroups compared to the reference, with a reduced risk of CircS (OR (95% CI),0.57 (0.51 ~ 0.64), p < 0.001; 0.40 (0.36 ~ 0.45), p < 0.001). After adjusting for age, sex, race and BMI, the second and third tertile subgroups remained protective compared with the reference group, (OR (95% CI), 0.77 (0.68 ~ 0.87), p < 0.001; 0.81 (0.71 ~ 0.94), p < 0.004). The protective effect was only observed in the third tertile subgroup after adjusting for all covariates, (OR (95% CI), 0.85 (0.74 ~ 0.98), p < 0.027).
The second and third tertile subgroups in model 1 shown a significant protection against MetS and CircS comorbidity (OR (95% CI),0.58 (0.51 ~ 0.64), p < 0.001; 0.39 (0.34 ~ 0.44), p < 0.001). After adjusting for age, sex, race and BMI, the protection still existed (OR (95% CI), 0.80 (0.70 ~ 0.91, p < 0.001; 0.84 (0.72 ~ 0.97), p = 0.018). The protection in the third tertile subgroup was noticed (OR (95% CI), 0.87 (0.75 ~ 1.01), p = 0.026) (Table 4).
Table 4
Logistic regression analysis of the association between physical activity and indicated diseases.
Variables | Model1 | | Model2 | | Model3 |
OR (95%CI) | P | OR (95%CI) | P | OR (95%CI) | P |
MetS | | | | | | | | |
Tertile 1 | 1.00 (Reference) | | | 1.00 (Reference) | | | 1.00 (Reference) | |
Tertile 2 | 0.59 (0.54 ~ 0.65) | < .001 | | 0.82 (0.73 ~ 0.92) | < .001 | | 0.90 (0.80 ~ 1.01) | 0.085 |
Tertile 3 | 0.40 (0.36 ~ 0.44) | < .001 | | 0.85 (0.75 ~ 0.96) | 0.009 | | 0.87 (0.77 ~ 0.99) | 0.034 |
CircS | | | | | | | | |
Tertile 1 | 1.00 (Reference) | | | 1.00 (Reference) | | | 1.00 (Reference) | |
Tertile 2 | 0.57 (0.51 ~ 0.64) | < .001 | | 0.77 (0.68 ~ 0.87) | < .001 | | 0.89 (0.78 ~ 1.01) | 0.064 |
Tertile 3 | 0.40 (0.36 ~ 0.45) | < .001 | | 0.81 (0.71 ~ 0.94) | 0.004 | | 0.85 (0.74 ~ 0.98) | 0.027 |
With CircS and MetS | | | | | | | | |
Tertile 1 | 1.00 (Reference) | | | 1.00 (Reference) | | | 1.00 (Reference) | |
Tertile 2 | 0.58 (0.51 ~ 0.64) | < .001 | | 0.80 (0.70 ~ 0.91) | < .001 | | 0.91 (0.80 ~ 1.04) | 0.168 |
Tertile 3 | 0.39 (0.34 ~ 0.44) | < .001 | | 0.84 (0.72 ~ 0.97) | 0.018 | | 0.87 (0.75 ~ 0.98) | 0.026 |
OR: Odds Ratio,CI: Confidence Interval |
Model1: Crude |
Model2: Adjust: Gender, Age, Race, BMI |
Model3: Adjust: Gender, Age, Race, Education_level, Marital_status, PIR_group, BMI, Smoking, Drinking, Covered_by_health_insurance |
Dose-response relationship between physical activity and three diseases
RCS was employed to analyze the dose-response relationship between physical activity and the three diseases. After adjusting for all confounders, we noticed that the risk of MetS declined with the increasing physical activity (p for overall < 0.001, p for nonlinear < 0.001), whereas the risk of CircS and its comorbidity with MetS, showed a U-shaped trend (p for overall < 0.001, p for nonlinear < 0.001), decreasing followed by increasing (p for overall < 0.001, p for nonlinear < 0.001). Interestingly, the recommended physical activity range for CircS was 0-590 MET/week, whereas the recommended physical activity range for MetS and CircS comorbidity was 0-595 MET/week (Fig. 2).
Subgroup analysis of the association between physical activity and three diseases
We further analyzed the relationship between physical activity and the risk of three diseases by subgroup analysis. The results suggested that physical activity may reduce the risk of MetS in middle-aged adults, other races, college and above, married, PIR > 1.35, and alcohol drinkers (Table 5).
Table 5. Subgroup analysis of the association between physical activity and MetS
There was an interaction between physical activity and age on the risk of CircS (p = 0.035), as indicated by the no protection in the young population (p > 0.05), but significant protection in the middle-aged or the elderly (p < 0.01). In addition, physical activity was more protective against CircS in men (0.78 (0.62,0.98), p = 0.035) than in women (0.84 (0.74,0.96), p = 0.012). Other Hispanics, college or higher, married, PIR < 1.35, BMI < 25 or ≥ 30, non-smokers or ex-smokers, and non-drinkers, all had a significantly lower risk of CircS with increased physical activity (p < 0.05) (Table 6).
Table 6. Subgroup analysis of the association between physical activity and CircS.
Finally, women, 45–64 years old, > 65 years old, college or higher, married, BMI < 25, never smoked or ex-smoked, and non-drinkers may benefit from the physical activity on CircS and MetS comorbidity (Table 7).
Table 7. Subgroup analysis of the association between physical activity and CircS and MetS comorbidity.