Characteristics of physical function and body composition among community-dwelling older females with and without locomotive syndrome

Abstract

[Purpose] This study aimed to clarify the presence or absence of locomotive syndrome as determined by two-step and stand-up tests, which measure physical ability as well as the characteristics of physical function and body composition among community-dwelling older females. [Participants and Methods] The study included 36 community-dwelling older females (aged 75.3 ± 6.0 years), who were classified into two groups: those with and without locomotive syndrome following the locomotive syndrome criteria. Their physical function and body composition were evaluated and compared. [Results] No significant differences in body composition were observed between participants with and without locomotive syndrome, as defined by the locomotive syndrome criteria. However, significant differences were noted in grip strength on the left side and open-eyed one-legged standing, 5-m comfortable walking speed and the timed up-and-go test on both the right and left sides. [Conclusion] The results indicate that physical function is a valuable criterion for evaluating the older populations. However, components of body composition that reflect physical condition and function require validation.

INTRODUCTION

The Japanese population is aging rapidly. The average life expectancy in 2023 was 81.09 and 87.14 years for males and females, respectively, and is expected to continue to increase in the future¹⁾. As Japan becomes the world’s first aging society, understanding the physical function and body composition of older Japanese adults is becoming increasingly important. In Japan, the long-term care insurance system^2,3,4) often categorizes the physical capabilities of older people into two groups: those who require support and those who require nursing care. This classification is based on the general belief that individuals in supportive care conditions exhibit better physical function. However, under the long-term care insurance system, in determining the care level, the results of the certification survey are considered as “nursing care effort”; however, the care level does not necessarily reflect physical function⁵⁾. In addition, the level of nursing care serves as an indicator for older people, i.e., even the minimal assistance level, graded as 1, indicates the need for assistance. Thus, from the preventive care perspective, identifying frail older individuals is important before their certification for the nursing care level.

The Japanese Orthopaedic Association introduced the concept of locomotive syndrome (locomo) in 2007⁶⁾. This condition indicates impairment or decline in musculoskeletal function, which can be caused by aging or lifestyle habits, such as limited range of motion of the joints, and muscle weakness, such as sarcopenia. Individuals diagnosed with locomo are considered at high risk of needing long-term care in the future.

It has also been reported that the prevalence of locomo in the general population is higher in females than in men. The locomo assessment consists of three components: a stand-up test designed to evaluate lower limb muscle strength, a two-step test that evaluates walking ability using the maximum stride length, and the Locomo25 test that assesses subjective physical function and difficulties in daily living. The stand-up and two-step tests comprehensively evaluate walking ability, including muscle strength and balance, and are used to determine the physical function of older people. Identifying the indicators that differentiate individuals who fall into the locomo category from those who do not will facilitate the early detection of conditions that may lead to the need for nursing care, thereby offering insights from a preventive perspective. However, to our knowledge, no studies have investigated the differences in physical function and body composition among community-dwelling older people who undergo locomo assessments. We believe that the early identification of locomo status, which represents the stage before disease onset, could aid in preventing the necessity for nursing care.

Thus, this study aimed to clarify the differences in physical function and body composition among community-dwelling older people who have undergone locomo evaluations through the two-step and stand-up tests.

PARTICIPANTS AND METHODS

The participants included 36 community-dwelling older females aged ≥65 years (mean ± standard deviation of age, 75.3 ± 6.1 years) who were capable of walking to the measurement site located at the Odawara Campus of the International University of Health and Welfare, Odawara, Japan. This study received ethical approval from the International University of Health and Welfare Research Ethics Review Committee (Approval No. 22-lg-107). Participants were thoroughly informed both in writing and verbally about the purpose and content of the study and provided an explanation that the results of the study would be used solely for the intended purposes. Written consent was obtained from each participant. The baseline characteristics of the participants, including age, sex, and height, were collected. This study focuses on the physical functions of participants. Therefore, subjective questionnaire tests such as Locomo25 were excluded from the assessment of participants’ locomotion status, and stand-up and two-step tests were adopted. The presence or absence of locomotive syndrome was determined based on the following criteria: a two-step value of less than 1.3 in the two-step test, which corresponds to Locomo Level 1, or the inability to stand up on one leg from a 40 cm platform in the stand-up test, while being able to stand up with both legs from a 20 cm platform. In addition, left and right-hand grip strength as a measure of muscle strength, left and right open-eyed one-legged standing as a measure of balance, 5-m comfort walk as a measure of walking speed, time up and go test (TUG), and body composition were evaluated.

Body composition was assessed using the bioelectrical impedance analysis (BIA) method with the In Body 270 (InBody, Inc., Seoul, South Korea). Measurements included body weight, body mass index (BMI), body fat percentage, body fat mass, total muscle mass, right arm muscle mass, left arm muscle mass, trunk muscle mass, right leg muscle mass, left leg muscle mass, protein mass, and mineral content. Additionally, skeletal muscle index (SMI), which is used as an indicator of sarcopenia, and fat-free mass index (FFMI), which includes skeletal muscle mass, were calculated from fat-free mass. The fat mass index (FMI), an index of fat mass, was also derived. The measurements were conducted in a standing position.

The stand-up and two-step tests were performed according to the Locomo brochure 2020⁷⁾. For the stand-up test, 10-, 20-, 30-, and 40-cm platforms were prepared, and the participants were instructed to stand up on both legs or on one leg without recoil from a position, with both hands crossed in front of the chest. On a 40-cm platform, participants were initially assessed to determine if they could stand on both legs, and if they succeeded, the next assessment involved standing on one leg. Success was defined as the ability to stand on both legs. Upon successful execution, the platform height was lowered in the order of 30, 20, and 10 cm, and the measurement result was recorded as the height of the lowest platform at which the participants could successfully stand on both legs.

For the two-step test, a standing long jump mat (KH-164 Kaneya Sangyo Co., Ltd., Osaka, Japan) with a memory description every 1 cm was used. The measured length was the distance from the toes of both legs at the start position to the toes at the end position when taking two steps forward at the maximum stride length. The maximum two-step length was then divided by the height, and the two-step value was calculated. Measurements were taken twice, and the maximum value was used as the representative value for the evaluation.

Participants were divided into two groups, a locomotive group and a non-locomotive group, based on the assessment of locomotive syndrome. Two-sample t-test was performed to compare the results between the two groups. Statistical analyses were conducted using SPSS Statistics for Windows, version 27 (IBM Corp., Armonk, NY, USA), with a significance level set at 5%.

RESULTS

Table 1 presents a comparison of the locomo group and non-locomo group results of the locomo evaluation among community-dwelling older adults. The Locomo group consisted of 12 participants, while the Non-Locomo group consisted of 24 participants. No significant differences in age, height, weight, right-hand grip strength, and body composition were observed. The left-hand grip strength and left and right one-legged open-eye standing durations were significantly higher in the non-locomo group than in the locomo group. The 5-meter comfortable walking time and TUG results showed faster performance in the locomo group (p<0.05).

Table 1. Comparison of community-dwelling elderly people with and without a locomotive syndrome assessment.

	Locomo group	Non-locomo group	p-value
	(n=12)	(n=24)
Age (years)	75.9 ± 7.1	74.9 ± 5.5	0.737
Height (cm)	155.5 ± 8.7	154.2 ± 7.4	1.000
Weight (kg)	52.5 ± 11.4	49.2 ± 8.3	0.373
BMI (kg/m2)	21.7 ± 4.4	20.7 ± 2.7	0.411
Body fat percentage (%)	26.6 ± 10.9	24.4 ± 7.2	0.763
Body fat mass (kg)	14.8 ± 8.5	12.2 ± 4.4	0.650
Fat-free mass (kg)	37.2 ± 6.8	37.1 ± 6.2	0.450
Right upper limb muscle mass (kg)	1.7 ± 0.5	1.6 ± 0.5	0.524
Left upper limb muscle mass (kg)	1.7 ± 0.5	1.6 ± 0.5	0.174
Trunk muscle mass (kg)	15.9 ± 3.1	15.3 ± 3.0	0.440
Right lower limb muscle mass (kg)	5.8 ± 1.5	5.7 ± 1.3	0.788
Left lower limb muscle mass (kg)	5.7 ± 1.4	5.6 ± 1.3	0.675
Protein amount (kg)	7.3 ± 1.3	7.2 ± 1.3	0.614
Mineral amount (kg)	2.5 ± 0.4	2.5 ± 0.4	0.440
SMI (kg/m2)	5.8 ± 0.6	5.7 ± 0.5	0.763
FFMI (kg/m2)	13.4 ± 2.8	13.0 ± 1.8	0.788
FMI (kg/m2)	6.2 ± 3.7	5.2 ± 2.0	0.638
Right grip strength (kg)	25.0 ± 6.5	26.6 ± 8.5	0.356
Left grip strength (kg)	21.7 ± 4.5	25.0 ± 7.0	0.014	*
Right single leg standing time (sec)	30.7 ± 32.0	81.7 ± 37.7	0.003	*
Left single leg standing time (sec)	23.7 ± 24.1	71.2 ± 45.0	0.009	*
5 m comfortable walking speed (sec)	4.0 ± 0.8	3.0 ± 0.7	0.001	*
TUG (sec)	6.8 ± 2.6	5.5 ± 0.8	0.001	*

*p<0.05.

BMI: body mass index; SMI: skeletal muscle mass index; FFMI: fat free mass index; FIM: fat mass index; TUG: timed up & go test.

DISCUSSION

This study was conducted to characterize the body composition and motor function of community-dwelling older females as determined by locomo assessments involving the stand-up and two-step tests, which measure physical performance. No difference in body composition was observed between the locomo groups and non-locomo groups. Conversely, significant differences were observed in the physical functions related to the left-hand grip strength, left and right open-eyed one-legged standing duration, 5-m comfortable walking speed, and TUG. The locomo evaluation reflects the overall walking ability, including muscle strength and flexibility, and significant differences were found between the applicable and nonapplicable groups. As an effect of aging, the lower limbs show a marked decline with age from around the age of 20, and the rate of decline by location was greater in the lower limbs than in the upper limbs and trunk⁸⁾. In addition, a strong relationship was noted between lower limb muscle strength and balance in adults aged ≥65 years, and a decrease in muscle strength was reported to result in a decrease in balance⁹⁾. Given that the study participants were ≥65 years old, the age-related decline in lower limb muscle strength became more pronounced; therefore, significant differences were found in the physical function parameters of the left and right unilateral standing times, 5-m comfortable walking speed, and TUG. Regarding grip strength, approximately 90% of the Japanese are right-handed¹⁰⁾. The dominant hand is determined around the age of eight and tends to be used more often in daily life¹¹⁾. In this study, many participants were right-hand dominant, and we hypothesized that their muscle strength would be less likely to deteriorate because they use their right hand more often in daily life than their nondominant left hand. Thus, a significant difference was observed in the grip strength of the left hand.

In this study, no significant differences in body composition were observed between the locomo group and the non-locomo group. One possible explanation is the reported cutoff value for grip strength indicating suspected locomotive syndrome, which is 22 kg¹²⁾. The average right-hand grip strength in both the locomo and non-locomo groups exceeded 22 kg, suggesting that many participants in this study had relatively well-maintained physical function. Although many participants maintained their muscle strength, the decline in mobility is reported to begin gradually in the 50s¹³⁾; thus, we believed that the participants may have exhibited physical function decline. This finding indicates that despite minor differences in body composition during the prevention phase when assistance was deemed necessary, these variations were observed as differences in performance.

The results of this study imply that physical function serves as a useful criterion for assessing the state of older people before they need assistance. Conversely, body composition measurement is useful because it is a safe and straightforward method for assessing physical status¹⁴⁾. Thus, validating aspects of body composition that can reflect physical status in the same way as physical function is important, and further assessment of body composition is essential.

Conflict of interest

The authors have no conflicts of interest to declare.