# Bilateral Deficits during Maximal Grip Force Production in Late Postmenopausal Women
## 4 Discussion
\begin{table}
\begin{tabular}{c c c} \hline \hline  & **Bilateral Index** & **Central Pulse Pressure** \\ \hline Nondominant Hand MF & \(r=0.388;\)\(p=0.091\) & \(r=-0.483;\)\(p=0.031\)\({}^{*}\) \\ Dominant Hand MF & \(r=0.524;\)\(p=0.018\)\({}^{*}\) & \(r=-0.500;\)\(p=0.025\)\({}^{*}\) \\ Bilateral Hand MF & \(r=0.705;\)\(p=0.001\)\({}^{*}\) & \(r=-0.510;\)\(p=0.022\)\({}^{*}\) \\ Bilateral Index & - & \(r=-0.280;\)\(p=0.232\) \\ \hline \hline \end{tabular} Note: MF, maximal hand-grip force; asterisk (\({}^{*}\)) indicates \(p<0.05\).  
\end{table} 
Table 2: Correlation findings in late postmenopausal women. women may facilitate functional impairments in the dominant hand related to increased bilateral deficits. In addition, we found that higher cPP in late postmenopausal women was significantly related to less maximal hand-grip force produced by dominant and nondominant hand and both hands. Given the significant relationship between hand-grip force and muscle mass [63], our correlation findings support a proposition that sarcopenia older women showed higher levels of brachial pulse pressure than nonsarcopenia participants [64]. A potential mechanism underlying the relation of muscle mass to altered pulse pressure involves systemic inflammation markers. Increased circulating inflammation markers (e.g., c-reactive protein, interleukin-6, and tumor necrosis factor-alpha) were associated with reduced muscle strength and mass [65], and more inflammation markers may elevate pulse pressure by inducing endothelial dysfunction, increased arterial stiffness, and decreased nitric oxide bioavailability [66, 67]. Higher pulse pressure is often associated with an increase of overall cardiovascular events and mortality of cardiovascular diseases [39, 68]. Especially in postmenopausal women, managing risk factors of cardiovascular diseases is important because estrogen deficiency caused by menopause rapidly increases the risk of cardiovascular mortality [69]. Potentially, maximal hand-grip force production in either unilateral or bilateral conditions may additionally indicate risk of cardiovascular events in late postmenopausal women. Although we found bilateral deficit patterns in late postmenopausal women, some limitations that should be cautiously interpreted remain in this study. First, we did not control the ovarian cycle and measure sex hormones in young premenopausal women. Given that estradiol concentrations are presumably related to levels of interhemispheric inhibition [50, 51], different ovarian cycles in young premenopausal women might affect the bilateral index during maximal bilateral hand-grip contraction. Thus, future studies need to measure the bilateral index in young premenopausal women throughout the ovarian cycle to assess potential effect of estradiol levels on bilateral deficit patterns. Second, the current bilateral deficit patterns in late postmenopausal women may be influenced by interactive effects of aging and estrogen deficiency. To determine the potential effects of sex hormones on bilateral deficit patterns, future studies need to specify the relationship between altered levels of sex hormones and bilateral deficits in late postmenopausal women, and further test changes in bilateral deficits after hormone therapy interventions. Third, the lower levels of physical activity levels in late postmenopausal women may influence bilateral deficit patterns in their upper extremities, because older women with high levels of physical activity revealed greater muscle strength that potentially decreased bilateral deficit patterns [70]. Although we did not measure and specify different physical activity levels for late postmenopausal women, the potential relationship between physical activity and bilateral deficits in the upper extremities should be investigated in future studies. Lastly, in this study, we did not report the potential effects of greater bilateral deficits and less grip strength in the dominant hand on the execution of activities of daily living in late postmenopausal women.