An inverted J-shaped association of serum uric acid with muscle strength among Japanese adult men: a cross-sectional study

BACKGROUND: Uric 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. METHODS: This 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. RESULTS: After 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. CONCLUSION: This 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

Skin advanced glycation end product accumulation and muscle strength among adult men

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

Leg extension power is a pre-disaster modifiable risk factor for post-traumatic stress disorder among survivors of the Great East Japan Earthquake: a retrospective cohort study.

BACKGROUND: Post-traumatic stress disorder (PTSD) is a common psychological problem following natural disasters. Although pre-disaster risk factors are important for early detection and proactive support, the examination of such has been limited to sociodemographic factors, which were largely unaffected by the disasters. We examined the association between pre-disaster physical functioning and lifestyle and PTSD symptoms five months after the earthquake in the Great East Japan Earthquake survivors who were participating in a pre-existing cohort study. METHODS: We designed a retrospective cohort study of a cooperative association in Sendai from August 2010 to August 2011. In 2010, lifestyle, physical condition, and sociodemographic factors were examined by self-reported questionnaires completed by 522 employees of this organization. We also measured the leg extension power of all the participants. PTSD symptoms were evaluated by the Japanese version of the Impact of Event Scale-Revised (IES-R-J) following the earthquake of 2011. RESULTS: In multivariate linear regression analysis, leg extension power (β = -0.128, P = 0.025), daily drinking (β  = 0.203, P = 0.006), and depressive symptoms (β  = 0.139, P = 0.008) were associated with total score of the IES-R-J among men. Moreover, for the IES-R-J subscale, leg extension power was also negatively associated with Intrusion (β = -0.114, P = 0.045) and Hyperarousal (β = -0.163, P = 0.004) after adjusting for all other significant variables. For women, hypertension (β  = 0.226, P = 0.032) and depressive symptoms (β  = 0.205, P = 0.046) were associated with the total score of the IES-R-J. CONCLUSIONS: Leg extension power is a potentially modifiable pre-disaster risk factor among men for attenuating the severity of PTSD symptoms associated with great disasters such as the Great East Japan Earthquake among men

Relationship of leg extension power with each subscale scores of IES-R-J among men and women^a.

a<p>Adjusted for physical activiy (<1 METs·hours/week, 1–22 METs·hours/week, or≥23 METs·hours/week), smoking status (never, former, or current), drinking status (never, 1–6 day(s)/week, or 7 days/week), sleep duration (6–8 hours/day or not), tooth brushing (≥3 times/day or <3 times/day), eating breakfast (<4 times/week or ≥4 times/week), diabetes (no or yes), hypertension (no or yes), dyslipidemia (no or yes), depressive symptoms (SDS≥45), age (log-transformed), education (≥ college or < college), occupation (deskwork or non-desk work), marital status (unmarried or married), family loss (no or yes), property damage (other, partially damaged, or completely damaged), and work volume (unchanged, increased, or decreased).</p>b<p>All continuous variables have been log-transformed.</p

Location of the epicenter of the Great East Japan Earthquake and Oroshi-machi.

<p>(a) The epicenter of the East Japan Earthquake (cross) was under the Pacific Ocean about 150 km east of the Miyagi Prefecture. (b) The Sendai Oroshisho Center is located in Oroshi-machi in Eastern Sendai, where the tsunami approached within 2–3 km distance.</p

Participants characteristics and pre-disaster factors associated with the total score of IES-R-J in men (n = 399)^a.

a<p>IES-R-J, the Japanese version of the Impact of Event Scale-Revised; PA, physical activity; METs, metabolic equivalent of tasks; SDS, Self-rating Depression Scale.</p>b<p>Data are summarized by median (interquartile range) for continuous variables and by percentage for category variables.</p>c<p>All continuous variables have been log-transformed.</p>d<p>Data was measured in 2011 only.</p

Flow chart of the sample selection process.

<p>Flow chart of the sample selection process.</p