Aging is associated with decreased skeletal muscle function. Increased levels of advanced glycation end products (AGEs) in skeletal muscle tissue are observed with advancing age and in diabetes. Although serum AGE level is negatively associated with grip strength in elderly people, it is unknown whether this association is present in adult males. To determine the relationship between AGE accumulation in tissue and muscle strength and power among Japanese adult men. Skin autofluorescence (AF) (a noninvasive method for measuring tissue AGEs), grip strength (n = 232), and leg extension power (n = 138) were measured in Japanese adult men [median (interquartile range) age, 46.0 (37.0, 56.0) years]. After adjustment for potential confounders, the adjusted means [95% confidence interval (CI)] for grip strength across the tertiles of skin AF were 44.5 (43.2, 45.9) kg for the lowest tertile, 42.0 (40.6, 43.3) kg for the middle tertile, and 41.7 (40.3, 43.1) kg for the highest tertile (P for trend < 0.01). Moreover, the adjusted geometric means (95% CI) of leg extension power across the tertiles of skin AF were 17.8 (16.6, 19.1) W/kg for the lowest tertile, 17.5 (16.4, 18.7) W/kg for the middle tertile, and 16.0 (14.9, 17.1) W/kg for the highest tertile (P for trend = 0.04). Among Japanese adult men, participants with higher skin AF had lower muscle strength and power, indicating a relationship between AGE accumulation and muscle strength and power. A long-term prospective study is required to clarify the causality.

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Inflammation has been strongly related to metabolic syndrome (MetS). Periodontal disease is the most common chronic infection in adults. We investigated a cross-sectional (n = 925) and 3-year longitudinal (n = 685) relationship between the daily frequency of toothbrushing and MetS. In the cross-sectional analysis, the prevalence of MetS was 15.7%. After adjustment for potential confounding factors (including all lifestyle factors), the odds ratios (95% confidence interval [CI]) of having MetS in those who brushed 2 times/day and ≥ 3 times/day were 0.71 (0.48-1.05) and 0.47 (0.24-0.92), respectively, as compared with ratios in those with a toothbrushing frequency of ≤ 1 time/day. Increasing toothbrushing frequency tended to relate inversely to hypertriglyceridemia and high-sensitivity C-reactive protein. In the longitudinal analysis, 99 participants were newly diagnosed with MetS. The adjusted odds ratios (95% CI) of the MetS in participants who brushed 2 times/day and ≥ 3 times/day as compared with participants who brushed ≤ 1 time/day were 0.80 (0.49-1.31) and 0.43 (0.19-0.97), respectively. The frequency of toothbrushing was related inversely only to hypertriglyceridemia, consistent with the cross-sectional analysis. This study found that more frequent toothbrushing is related to a lower prevalence and incidence of MetS. These results suggest that more frequent toothbrushing may contribute to the prevention of MetS due to the inflammation/triglyceride pathway.

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BackgroundUric acid (UA) may protect muscle function from oxidative damage due to reactive oxygen species through its powerful antioxidant capacity. However, several studies have demonstrated that hyperuricemia is closely related to systemic inflammation and has oxidant properties effects, both of which may increase the risk of muscle strength loss. The purpose of this study was to examine the association of serum UA concentration with grip strength and leg extension power in adult men.MethodsThis study is a cross-sectional survey in which 630 Japanese male employees aged 30 years and older participated. Five hundred and eighty-six subjects participated in the measurement of grip strength, and 355 subjects participated in the measurement of leg extension power. Blood samples were obtained for serum UA analysis.ResultsAfter adjustment for potential confounders, grip strength differed significantly between participants with and those without hyperuricemia (geometric mean and 95% confidence interval [CI]: 40.3 [39.2–41.3] kg vs. 41.9 [41.3–42.5] kg; P = 0.01). In addition, serum UA levels (quartiles) showed an inverted J-shaped curve with grip strength (mean and 95% CI: Q1, 41.6 [40.6–42.6] kg; Q2, 42.2 [41.2–43.2] kg; Q3, 41.8 [40.8–42.8] kg; Q4, 40.4 [39.3–41.4] kg; P for quadratic trend = 0.05). The results in the leg extension power group were similar to those observed in the grip strength group.ConclusionThis population-based cross-sectional study shows for the first time that hyperuricemia is associated with poor muscle strength. Moreover, the results indicate an inverted J-shaped association between serum UA quartiles and muscle strength.