BJMB

Brazilian Journal of Motor Behavior

Special issue:

“Manipulation of sensory information on postural control

performance of children, young and older adults”

Magalhães,

Scheidegger,

Rinaldi

2024

VOL.18

N.1

https://doi.org/10.20338/bjmb.v18i1.406

1 of 8

The complexity of the handgrip task modulates postural performance in older adults

GABRIELA V. MAGALHÃES

| NAYARA C. A. SCHEIDEGGER

| NATALIA M. RINALDI

Biomechanical Analysis of Movement Laboratory (Bio.Mov), Physical Education and Sports Center, Federal University of Espírito Santo, Vitória, ES, Brazil

Correspondence to: Gabriela Vigorito Magalhães

Centro de Educação Física e Desportos, Av. Fernando Ferrari, 514 – Goiabeiras, Vitória, ES, Brazil, 29075-910.

Phone: +55 27 4009-2638

email: gabivigorito@gmail.com

https://doi.org/10.20338/bjmb.v18i1.406

HIGHLIGHTS

• Aging influences the performance of the combined task

of posture and prehension.

• Older had worse postural control on the unstable

surface when compared to younger.

• Postural control is modulated to the difficulty of the

grasping tasks and the bases.

ABBREVIATIONS

COP Center of pressure

OA Older adults

YA Young adults

PUBLICATION DATA

Received 04 12 2023

Accepted 03 06 2024

Published 20 07 2024

BACKGROUND: The acts of reaching and grasping objects are involved in the performance

of daily activities. There is a gap in the understanding of how the complexity of the grasping

task associated with changes in the base of support influences postural control performance

in the older population.

AIM: To investigate the postural control performance of older people as they performed the

grasping movement, with different levels of task difficulty and complexities of the base of

support.

METHOD: 15 young and 15 older adults participated. The participants stood on a force

platform and performed: 1) Reaching a heavy object; 2) Reaching a light object in rigid and

unstable base conditions. The variables analyzed were: area, mean velocity, and mean

displacement amplitude of the center of pressure (COP).

RESULTS: Older had higher COP velocity in the anteroposterior and mediolateral directions,

as well as in the rigid and unstable bases. They also had a larger COP area in the rigid and

unstable base of support, and for all gripping tasks. In both groups, the mean amplitude of

COP displacement in the rigid base was higher while gripping a heavy object than while

gripping a light object or performing a non-gripping task.

CONCLUSION: Postural control in the older adults is mainly influenced by the difficulty of

grasping tasks. It is possible to identify the postural control performance of the older while

they grasp objects during daily activities and to assess how these activities disturb balance,

which makes it possible to draw up guidelines to improve postural performance.

KEYWORDS: Postural control | Dual task | Grasping | Older adults

INTRODUCTION

Postural instability is defined as the inability to integrate sensory information and determine body oscillations in the upright

position while maintaining balance

. With aging, the sensory systems (visual, somatosensory, and vestitubular) responsible for postural

control become unable to maintain the center of pressure (COP) over the base of support, which causes physical decline and,

consequently, impairs the performance of daily activities

. The worsening in the performance of activities is especially evident when older

people perform associated tasks, such as reaching and holding a water bottle

, because when a secondary task is performed

concurrently with a postural one, attentional resources are divided

and influenced by the complexity and type of the task.

As a result, when older people are subjected to a dual-task condition, they have worse postural control performance

. Greater

amplitude of oscillation

, anteroposterior and lateral median velocity

, and area of oscillation of the COP

were identified when older

adults were subjected to cognitive tasks involving counting and calculations. The worse postural performance becomes even more

evident when older people are subjected to sensory disturbances

such as an unstable support base. This behavior shows that additional

tasks impact postural control performance and lead to greater difficulty in allocating attention to it, which causes balance impairment and

affects the performance of daily activities

The acts of reaching and grasping objects are involved in the performance of daily activities and are essential in interactions

with the environment, such as reaching when drinking water from a bottle and grasping objects of different weights, sizes, and shapes. It

has been identified that, when performing the reaching movement, older people have a greater amplitude of COP displacement than

young adults

10,11

, which reflects an adaptation to the decline of movement control systems due to the aging process

Although postural control performance has been investigated under different base conditions

9,12,13

or associated with the

BJMB

Brazilian Journal of Motor Behavior

Magalhães,

Scheidegger,

Rinaldi

2024

VOL.18

N.1

https://doi.org/10.20338/bjmb.v18i1.406

2 of 8

Special issue:

“Manipulation of sensory information on postural control

performance of children, young and older adults”

movement of grasping the same object without manipulation of characteristics

3,10,11

, there is a gap in the literature on how the complexity

of tasks, adjusted in this study by changing the weight of objects, along with changes in the base of support (rigid or unstable), influences

postural control performance in the older population. Thus, the objective of this study was to investigate the postural control performance

of older people as they performed the grasping movement, with different levels of task difficulty and complexities of the base of support. It

is expected that 1) older adults will have worse postural control performance than young adults and 2) poorer performance will be seen

when individuals – especially the older people – are subjected to more complex tasks, such as grasping heavier objects, and while the

unstable base is used.

METHOD

Participants

This study was carried out at the Laboratory of Biomechanical Analysis of Movement (Bio.Mov) at the Center for Physical

Education and Sports of the Federal University of Espírito Santo (CEFD/UFES). The participants were 15 younger adults and 15 older

adults. All the participants were right-handed, able to stand without support and had normal or corrected vision, preserved cognitive

functions to understand the tasks, and no neurological alterations, self-reported musculoskeletal disorders or dizziness preventing them

from performing the experimental tasks. After agreeing to participate in the study, all individuals signed an informed consent form

approved by the Research Ethics Committee of UFES (CAAE: 62459922.2.0000.5542).

Initially, anthropometric measurements of weight and height, as well as upper limb length, were taken. To verify the inclusion

criteria, anamnesis was conducted. The Baecke Questionnaire for young adults

and the modified version for the older

were used to

assess participants’ physical activity levels. The cognitive function of older people was assessed using the Mini Mental State Examination

, and their static and dynamic balance was assessed with the MiniBESTest

Task and equipment

The participants were asked to stand barefoot on a force platform, keep an upright posture, and remain as stable as possible

for 30 seconds, keeping their arms at their sides, their head still, and their gaze fixed on a target one meter away. When requested,

participants performed the following movements: 1) reaching a heavy object; 2) reaching a light object, and 3) standing still. The reaching

movements were performed with the right upper limb, and participants stood both on a rigid support base, on the force platform, and on

an unstable base, on the foam. The foam was 0.47m length, 0.38m width and 0.055m thick. The mass of the foam used was 0.491 kg

and the volume was 0.009 m3. The density of the foam was 50 kg/m

. The light object was always positioned to the left of the participant,

and the heavy object was positioned to the right. The weight of the objects was not initially informed, which made the manual task

unpredictable and prevented any compensations anticipating the movement. The commands given were to "pick up the object to the

right/left". Thus, the difficulty level of the grasping task was manipulated by using objects that differed in weight, and the postural task was

manipulated by changing the type of support base. Three randomized trials were carried out for each baseline and object condition,

which resulted in a total of 18 trials per participant.

The objects (two black wooden cylinders weighing 0.5 and 1.5 kg, with a diameter of 15 cm and a height of 10 cm) were

positioned on a wooden stand in front of the participants, at a height adjusted in relation to the greater trochanter of their femur and a

distance corresponding to 50% of the length of their right upper limbs (Figure 1). For subsequent kinematic analysis of the grasping

movement, a reflective marker was positioned on top of each object. The participants wore a black glove in which reflective markers were

also placed, specifically on the wrist joint, on the distal phalanx of the first finger, and on the distal phalanx of the second finger of the

right hand.

For data collection, a force platform (Biomec 400, EMGSystem do Brasil, SP, LTDA) with a collection frequency of 100 Hz was

used.

Dependent variables

- Mean total velocity: time domain variable, expressed in centimeters per second, was calculated from the displacement of the

total oscillation of the center of pressure in the anteroposterior and mediolateral directions for the total time of each trial;

- Mean amplitude of center of pressure displacement: time domain variable, expressed in centimeters, was calculated between

the maximum and minimum distance from the center of pressure for the anteroposterior and mediolateral directions;

- Area: spatial variable, expressed in centimeters squared, estimates the dispersion of the CP data through the calculus of the

statokinesigram area. It was calculated using an ellipse that contains 95% of the center of pressure data, being the two axes of the ellipse

calculated through the measures of the center pressure signals dispersion.

BJMB

Brazilian Journal of Motor Behavior

Magalhães,

Scheidegger,

Rinaldi

2024

VOL.18

N.1

https://doi.org/10.20338/bjmb.v18i1.406

3 of 8

Special issue:

“Manipulation of sensory information on postural control

performance of children, young and older adults”

Figure 1. (A) Side view of the experimental setup, with the participant positioned on the force platform, in relation to the object and the screen, (B) Anterior view of the

markers on the wrist joint, the distal phalanx of the thumb and of the second finger of the right hand, and on top of the light and heavy objects. Legend: m (meters).

Statistical analysis

The Shapiro Wilk test and Levene's test were used to verify the normality and homogeneity of the data, respectively. If the data

differed from a normal distribution, z-score standardization was used for subsequent parametric analysis. One-way ANOVA was carried

out to compare age, anthropometric characteristics (height, body mass), and clinical characteristics (age, Baecke assessment scores)

between the two groups (young and older adults). To analyze postural control, 2 MANOVAs (groups [young and older adults] X object

[none, light and heavy] X surface [rigid and unstable]) with repeated measures were carried out for the following sets of dependent

variables: (1) mean velocity in the anteroposterior and mediolateral directions and (2) mean amplitude of displacement in the

anteroposterior and mediolateral directions. In addition, an ANOVA with the same factors (group x object x surface) was carried out for

area. When necessary, Bonferroni Post Hoc tests were conducted, and a significance level of p≤0.05 was adopted for all analyses.

RESULTS

Sample characterization

A total of 15 older people, nine women and six men, and 15 young adults, five women and ten men, participated in this study.

Table 1 shows the clinical characteristics of the older and young people in this study, the respective statistical tests, and the mean and

standard deviation values for the clinical tests (Baecke, MiniBestest, MiniMental).

Table 1. Mean and standard deviation of age, anthropometric characteristics, and clinical characteristics of the young and older adults

groups, with the respective statistical analyses (one-way ANOVA).

Clinical Variables

Older adults

(n=15)

Young adults

(n=15)

ANOVA

(one way)

Age (years)

65.6 (4.1)

26.4 (5.16)

1-28

= -526.06, p≤0.001*

Height (m)

1.62 (0.08)

1.74 (0.075)

1-28

= 15.93, p≤0.001*

Body Mass (kg)

65.11 (7.70)

70.36 (12.58)

1-28

= 1.90, p=0.179

Baecke Questionnaire (points)

14.25 (3.80)

9.42 (1.49)

1-28

= 20.94 p=0.179

Mini-Mental (points)

27.93 (0.85)

MiniBESTest (points)

30.0 (1.32)

Legend: n (number of participants); m (meters); kg (kilogram). *Difference between older adults and young adults (p≤0.05).

Control postural analysis

The group and interaction effects for the postural control variables will be described below.

COP velocity

MANOVA revealed a group effect (Wilks’ Lambda=0.447; F

2,24

= 14.832, p≤0.001) and a base*group interaction (Wilks’

Lambda=0.560, F

2,24

=9.436, p=0.001). ANOVA revealed a group effect for COP velocity in the anteroposterior (F

1,25

=25.132, p≤0.001)

and mediolateral (F

1,25

=28.517, p≤0.001) directions, and a base*group interaction effect for COP velocity in the anteroposterior

1,25

=16.292, p≤0.001) and mediolateral (F

1,25

=10.363, p=0.004) directions.