Normative Data for Gait Speed and Height Norm Speed in ≥ 60-Year-Old Men and Women

Introduction

Gait speed is a significant determinant of health.¹ In older adults, evidence suggests that gait speed can predict several adverse outcomes, including mortality,² functional dependence,³ well-being,⁴ cognitive decline⁵ and frailty.⁶ Thus, health-related benefits of gait speed are of great importance for preserving a successful aging and being independent.

In order to compare pathological with normal gait speed, it is crucial to establish reference-based data to be interpretable. To date, several studies from United Kingdom,^7,8 Canada,^9,10 Sweden,¹¹ United States,^1,12,13 Japan^14–16 and Australia¹⁷ have examined and provided age-related changes and normative values for gait speed. In general, the aforementioned studies have observed that gait speed significantly declines with age in both sexes. However, no study has reported such data regarding Croatian older adults. It is estimated that the percentage of older people will exceed the number of young by 2050.¹⁸ In Croatia, 25.0% of the population is aged ≥ 65-year-old.¹⁹ Thus, specific normative data and graphical curves for gait speed should help health-related professionals in screening functional dependence and monitoring the effectiveness of rehabilitative interventions.¹⁷

Therefore, the main purpose of the study was to establish sex- and age-normative data for gait speed and height-normalized gait speed in older adults.

Materials and Methods

Study Participants

In this cross-sectional study, we recruited community-dwelling older men and women aged ≥60 years who were part of the Society for Sport Recreation for older people in the city of Zagreb. First, we briefly described the main aims, hypotheses and practical implications of the study. The Society has approximately 4.000 registered users. By using the confidence level of 95% and confidence interval of 4, our estimated sample size was 522. We increased the sample size, due to possible missing data. To be included in the study, participants needed to be: (1) ≥60 years of age, (2) without gait impairments or using an aid to walk, (3) without chronic diseases which may affect gait patterns and (4) without cognitive problems. Our final sample included 565 older men and women. Basic descriptive statistics of the study participants are presented in Table 1. Before the study began, each participant had signed a written informed consent to participate in the study and agreed that the data could be used for scientific purposes. Data collection was anonymous and in accordance with the Declaration of Helsinki (1964). Procedures in the study were approved by the Ethical Committee of the Faculty of Kinesiology.

Table 1 Basic Descriptive Statistics of the Study Participants (N = 565)

Gait Speed

To measure gait speed, we used a pressure platform (ZEBRIS company, FDM; GmbH, Munich, Germany; number of sensors: 11,264; sampling rate: 100 Hz; sensor area: 149 cm × 54.2 cm). The procedure of previously published papers related to this topic was followed.²⁰ In brief, the walkway was 10.5 m in length (1.5 m platform and 4.5 m custom-designed dense material before and after the platform). The protocol consisted of a set of instructions to participants to walk at a preferred speed and to look straightforward across the platform being barefoot and without targeting the platform. When the participants finished walking across a 10.5 m walkway, they needed to turn around for 180° and continue to walk over the platform until they reached the end of the walkway. The aforementioned protocol was repeated once again with a total of four trials across the platform. If we detected obvious gait deviations, we discarded the trials and repeated the protocol. Height and weight were objectively measured by using anthropometric kit and digital scale.

Data Analysis

Basic descriptive statistics are presented as mean (x) and standard deviation (SD). Differences between sex (men vs women)- and age-specific (60–65 years, 66–70 years, 71–75 years and ≥76 years) variables were calculated by univariate analysis of variance (ANOVA). We used Cole’s Lambda, Mu and Sigma (LMS) method, in which the optimal power to obtain normality is summarized by a smooth (L) curve and trends in the mean (M) and coefficient of variation (S) are similarly smoothed.²¹ Next, all three curves (L, M and S) are summarized based on the power of age-specific Box–Cox power transformations for normalizing the data. Smoothed curves were presented for the 20th, 40th, 60th and 80th percentiles and further categorized as “very slow” (<20th), “slow” (20th–40th), “average” (40th–60th), “fast” (60th–80th) and “very fast” (>80th) gait speed.¹⁶ Height-normalized gait speed was calculated by dividing gait speed with body height. Multiple regression analysis with the coefficient of correlation (r) and determination (r²) was used to calculate the associations between sex, age and body mass index with gait speed. The p-value in Table 1 represents the general level of statistical computation. All analyses were performed in Statistical Packages for Social Sciences version 23.0 (SPSS Inc., Chicago, Illinois, USA).

Results

Basic descriptive statistics are presented in Table 1. Men were taller, heavier and had higher waist circumference values, compared with women. Body mass index did not significantly differ between men and women. When comparing the youngest (60–65-year-old) and the oldest (≥ 76-year-old) group, gait speed declined by 21.4% in men and 27.9% in women. In both men and women, the steepest decline between ages 60–65 years and ≥76 years was observed.

Table 2 shows sex- and age- specific normative data for gait and height-normalized gait speed. In men aged 60–65 years, 66–70 years, 71–75 years and ≥76 years, the median values were 1.38 m/s, 1.30 m/s, 1.22 m/s and 1.08 m/s for gait speed and 0.80 m/s, 0.74 m/s, 0.70 m/s and 0.63 m/s for height-normalized gait speed. In women aged 60–65 years, 66–70 years, 71–75 years and ≥76 years, the median values were 1.41 m/s, 1.27 m/s, 1.08 m/s and 0.92 m/s for gait speed and 0.87 m/s, 0.78 m/s, 0.69 m/s and 0.56 m/s for height – normalized gait speed. Smoothed 20th, 40th, 60th and 80th percentile curves are presented in Figure 1.

Table 2 Normative Data for Gait Speed and Height-Normalized Gait Speed in the Study Participants (N = 565)

Figure 1 Reference curves for gait speed (A and C) and height-normalized gait speed (B and D) in men (upper row) and women (lower row).

In both men and women, gait speed was significantly correlated with age (r = - 0.49 and −0.47, p < 0.001), waist circumference (r = - 0.28 and −0.21, p < 0.001) and body mass index (r = - 0.24 and −0.20, p < 0.002). Multiple regression analysis in Table 3 showed that being women, older age and higher levels of body mass index were significantly associated with slower gait speed (multiple r = 0.54, r² = 29.1%, p < 0.001).

Table 3 Predictors of Gait Speed in the Study Participants (N = 565)

Discussion

The main purpose of the study was to establish sex- and age-normative data for gait speed and height-normalized gait speed in older men and women. Our main findings are: (1) gait speed significantly declines with age in both men and women, (2) median values for gait speed range between 1.08 m/s and 1.38 m/s in men and between 0.92 m/s and 1.41 m/s in women across the age groups and (3) being women, older age and higher body mass index values predict “slower” gait speed.

The gait speed and height-normalized gait speed obtained in our study are consistent with previous studies conducted among older individuals,^1,12,13 being around 1.30 m/s. Of note, it should be highlighted that the data obtained in this study were collected by using a pressure platform, which is a more reliable and valid method, compared to other alternative methods.^13,16 Another study conducted among Japanese older adults using a pressure platform for assessing reference data of gait parameters showed, that median gait speed was 1.26 (0.24) m/s,¹⁶ which is equal to our findings. Most recently, cut-off values of 0.88 m/s and 0.85 m/s have been proposed in predicting foot pain and the risk of falls in community-dwelling older women,²⁰ pointing out that the proposed sex- and age-reference data for gait speed may serve as a potential screening tool in targeting those individuals with slower gait speed for special interventions that improve and enhance gait biomechanics.

Regarding gender differences, previous studies have shown that men walk faster, compared to women,^1,14,17 which is often attributed to the larger step and stride length produced by men. When gait speed was normalized to height, our findings also showed significant differences between sexes, indicating that sex and height are in function of gait speed in this sample.

The present study also observed a significant decline in gait speed across the age groups; younger participants were faster, compared to older ones. Our findings are in line with previous ones conducted among older individuals.^10,13,16,17 Specifically, Himann et al¹⁰ reported that gait speed decreased between 12% and 16% per decade after the age of 70. In the study by Hollman et al¹³ gait speed did not significantly change between the ages 70–80 yet decreased rapidly past the age of 80.

Gait speed represents a powerful marker of health¹ and walking faster is often strongly associated with a lower likelihood of developing some diseases, including all-cause mortality,² and may additionally prevent from future functional dependence,³ lower level of well-being,⁴ faster cognitive decline⁵ and frailty.⁶ According to previous longitudinal evidence, gait speed can predict the level of survival in older individuals.² The mechanism between gait speed and lifelong independence lies in requiring energy, movement control and constant support during walking, which often reflects on multiple organ systems functioning, like musculoskeletal system or high-energy cost.² Also, a previous systematic review has shown that “slower” gait speed serves as a significant predictor of several adverse outcomes, including mobility disability, cognitive decline, mortality, the risk of falls and early institutionalization.²² Specifically, most of the aforementioned negative health outcomes are characteristic of older individuals walking <0.80 m/s at the usual pace, pointing out that such a threshold is “easy-to-remember” and should be used in clinical trials as exclusion/inclusion criteria or as an outcome.²² In that way, measuring gait speed should be used in health-related settings for obtaining an extra predictor of overall health in older individuals.

This study is not without limitations. First, by using a cross-sectional design, the causality of the association between sex, age and gait speed cannot be determined. Second, selection bias could be possible, since participants volunteered in the study and came to measurements by themselves.¹⁶ Third, we did not collect additional gait performance information, like spatial or temporal parameters strongly associated with gait speed.¹⁶ By providing such information, we could have made the relations between walking speed at the usual pace and the risk of falls. Finally, participants walked barefoot across the pressure platform. In barefoot walking, step length is larger, stance duration is shorter, and cadence is higher than in walking while wearing standard shoes.^16,23

Conclusions

This is the first examining gait speed and height-normalized gait speed in a sample of Croatian community-dwelling older individuals by using a pressure platform. Although gait speed reference values have been widely established, newly proposed values for Croatian older adults should serve for gait assessment in both clinical and community-dwelling settings.