Associations of Sleep Quality with Gait Speed and Falls in Older Adults: The Mediating Effect of Muscle Strength and the Gender Difference

Abstract

<b><i>Introduction:</i></b> Although previous studies have reported the significant associations of sleep quality with gait speed and falls, the mechanisms underlying these associations are unclear. We aimed to examine the gender-specific associations of sleep quality with gait speed and falls among older adults and to explore the possible mediating effect of muscle strength on these relationships. <b><i>Methods:</i></b> Data were taken from wave 6 (2012–2013) of the English Longitudinal Study of Aging (ELSA), including 7,664 participants aged 60 years and older. Sleep quality and falls were assessed by self-report. Gait speed was measured by the “timed walking test” and then adjusted by height. As an indicator of overall muscle strength, grip strength was measured by using the Smedley dynamometer. Baron and Kenny’s causal steps and the Karlson/Holm/Breen method were used to examine the mediating effect. <b><i>Results:</i></b> Higher sleep quality was associated with the higher level of gait speed (β = 0.008, <i>p</i> = 0.031 in men; β = 0.008, <i>p</i> = 0.017 in women) and with lower prevalence of falls (OR = 0.878, 95% CI: 0.773, 0.998 in men; OR = 0.874, 95% CI: 0.792, 0.965 in women). Grip strength mediated these associations in men but not in women, and the mediating effects of grip strength can explain 23.74 and 11.01% of the total effect of sleep quality on gait speed and falls, respectively. <b><i>Conclusion:</i></b> Our findings help explain the mechanism underlying the associations of sleep quality with gait speed and falls. Effort to maintain the mobility of the older men should focus on improving both sleep quality and muscle strength.

The Association Between Gait Speed and Sleep Problems Among Chinese Adults Aged 50 and Greater

“…With regard to the role of sex differences in the relationship between sleep problems and gait speed, our finding suggested that a significant association of slower gait speed with poor sleep quality and longer sleep duration were only observed among male participants, which was in agreement with previous studies ( Goldman et al, 2007 ; Zhang et al, 2021 ). Goldman et al (2007) suggested that compared to adults with normal sleep duration (7–8 h), longer sleep duration in both male and female adults was associated with slower normal walking speed.…”

“… Goldman et al (2007) suggested that compared to adults with normal sleep duration (7–8 h), longer sleep duration in both male and female adults was associated with slower normal walking speed. Another study showed that the link between sleep problems and slower walking speed is apparent in England females and males ( Zhang et al, 2021 ). As there are few studies on exploring the relationship between gait speed and sleep, the reasons for these different results may be the influence of different populations and sample sizes in different regions and sample sizes of populations.…”

“…One explanation may be that slow walking speed is attributed to reduced muscle strength and function. Sleep-related problems can result in imbalance of endocrine secretion associated with skeletal muscle health (e.g., insulin-like growth factor, irisin, and inflammatory response), which possibly disrupts the protein synthesis and increases the protein degradation, thereby limiting the increase in muscle strength ( Tan et al, 2020 ; Zhang et al, 2021 ). A decline in leg muscle strength can cause poor imbalance and an effective protective response, possibly influencing the walking speed ( Zhang et al, 2021 ).…”

“…Sleep-related problems can result in imbalance of endocrine secretion associated with skeletal muscle health (e.g., insulin-like growth factor, irisin, and inflammatory response), which possibly disrupts the protein synthesis and increases the protein degradation, thereby limiting the increase in muscle strength ( Tan et al, 2020 ; Zhang et al, 2021 ). A decline in leg muscle strength can cause poor imbalance and an effective protective response, possibly influencing the walking speed ( Zhang et al, 2021 ). Further, the limitation of physical function (e.g., slow walking speed) may affect the sleep quality in adults ( Goldman et al, 2007 ; Zhang et al, 2021 ).…”

“…A decline in leg muscle strength can cause poor imbalance and an effective protective response, possibly influencing the walking speed ( Zhang et al, 2021 ). Further, the limitation of physical function (e.g., slow walking speed) may affect the sleep quality in adults ( Goldman et al, 2007 ; Zhang et al, 2021 ). Other explanations may be that the association between gait speed and sleep was influenced by the deterioration in executive function, which contributes to regulation of the gait control ( Watson et al, 2010 ).…”