Effects of neuromuscular electrostimulation of quadriceps on the functionality of fragileand pre-frail hospitalized older adults: randomized clinical trial

ABSTRACT

This work aimed to evaluate the effects of neuromuscular electrostimulation (NMES) on the functionality of frail and pre-frail hospitalized older adults. It is a randomized clinical trial that dealt with 17 hospitalized people. Anthropometric, socioeconomic and clinical data were evaluated, followed by the scale proposed by Fried to identify the frailty syndrome. In addition, we evaluated thigh perimetry and lower limb strength according to the Medical Research Council (MRC) as well as conducted the sit-to-stand test (STST). Patients were allocated to the control group (CG; n=9), aged 67.7±6.9 years and intervention group (IG; n=8), aged 71.2±5.6 years. Both groups received conventional physiotherapy care. The NMES protocol was applied only in the intervention group. The groups were similar in terms of sociodemographic, anthropometric profile, clinical characteristics and continuous use of medications. There were significant effects of NMES when compared to CG for right thigh perimetry (p=0.03); number of repetitions in STST (p=0.004) and quadriceps muscle strength (p=0.01) evaluated by the MRC scale. The quadriceps muscle training with the aid of NMES was effective in frail and pre-frail hospitalized people, promoting increased strength and functional performance.

KEYWORDS
Age; Electric Stimulation; Muscle Strength; Frailty

RESUMO

Este artigo teve como objetivo avaliar os efeitos da eletroestimulação neuromuscular (EENM) sobre a funcionalidade de idosos frágeis e pré-frágeis hospitalizados. Trata-se de um ensaio clínico randomizado com 17 idosos hospitalizados. Foram avaliados dados antropométricos, socioeconômicos e clínicos, seguido da escala proposta por Fried para identificação da síndrome da fragilidade. Além disso, foram avaliados a perimetria da coxa e a força de membros inferiores pelo Medical Research Council (MRC) e teste de sentar e levantar (TSL). Os pacientes foram randomizados em grupo-controle (GC; n=9), com idade de 67,7±6,9 anos e grupo intervenção (GI; n=8), com idade de 71,2±5,6 anos. Ambos os grupos receberam atendimento de fisioterapia convencional. O protocolo de EENM foi aplicado somente no grupo intervenção. Os grupos foram semelhantes quanto ao perfil sociodemográfico, antropométrico, quanto às características clínicas e quanto ao uso contínuo de medicamentos. Houve efeitos significativos da EENM quando comparados ao GC para perimetria da coxa direita (p=0,03); para o número de repetições no TSL (p=0,004) e para a força muscular do quadríceps (p=0,01), avaliados pela escala MRC. O treinamento muscular de quadríceps com a EENM foi efetivo nos idosos frágeis e pré-frágeis hospitalizados, promovendo aumento da força e do desempenho funcional.

Descritores:
|Idoso; Estimulação Elétrica; Força Muscular; Fragilidade

RESUMEN

Este artículo tuvo como objetivo evaluar los efectos de la electroestimulación neuromuscular (EENM) sobre la funcionalidad de ancianos frágiles y prefrágiles hospitalizados. Es un ensayo clínico aleatorizado en el cual participaron 17 ancianos hospitalizados. Se evaluaron los datos antropométricos, socioeconómicos y clínicos, seguidos de la escala propuesta por Fried para identificar el síndrome de fragilidad. Además, se evaluaron la perimetría del muslo y la fuerza de las extremidades inferiores utilizando el Medical Research Council (MRC) y el test de sentarse y levantarse (TSL). Los pacientes se asignaron aleatoriamente a un grupo de control (GC; n=9), con promedio de 67,7±6,9 años, y al grupo de intervención (GI; n=8), con 71,2±5,6 años. Ambos grupos recibieron fisioterapia convencional. El protocolo de EENM se aplicó solo al grupo de intervención. Los resultados de los grupos fueron similares en relación a las características sociodemográficas, antropométricas, clínicas y de uso continuo de medicamentos. Hubo efectos significativos de la EENM en comparación al GC para la perimetría del muslo derecho (p=0,03); para el número de repeticiones en el TSL (p=0,004) y para la fuerza muscular del cuádriceps (p=0,01), evaluados por la escala MRC. El entrenamiento muscular del cuádriceps con la EENM fue eficaz en los ancianos frágiles y prefrágiles hospitalizados, pues promovió un aumento de la fuerza y el rendimiento funcional.

Palabras clave:
|Anciano; Estimulación Eléctrica; Fuerza Muscular; Fragilidad

INTRODUCTION

Aging is a natural biological process, which involves a decline in systemic physiological functions, resulting in varying degrees of decreased functionality¹. Population aging is now a worldwide occurrence, and in Brazil the older population exceeded 14.5 million in 2000; it is estimated that in 2030 they will be 18.6% of Brazilians, and in 2060, 33.7%^{2), (3}. In Brazil, there have been significant changes in age structures in recent decades, with a decrease in fertility levels and in mortality, increasing life expectancy and population longevity^{3), (4}.

According to Arantes et al. ⁽⁵ frailty is a clinical syndrome of multifactorial nature, characterized by a state of physiological vulnerability due to decreased energy reserves and the ability to maintain or recover homeostasis after an event. Frailty indicates conditions of high risk of falls, hospitalization, disability, institutionalization and death⁶. Thus, the study of this syndrome in hospitalized older adults has clinical relevance. Therefore, the investigation of its presence allows health professionals to make an appropriate intervention, avoiding its harmful consequences to health.

In hospitalized older people, the diagnosis of frailty was associated with an increase in the number of hospitalized days and high mortality rates⁷. Identification of the stage that precedes the most serious manifestations, known as pre-frailty, has preventive potential. After the phenomenon onset, the therapeutic approach aims to prevent, postpone or mitigate the harmful effects of frailty on functional capacity and quality of life ^{(7), (8}.

Interest and research on muscle mass loss associated with loss of muscle function-strength or physical performance-in older adults has gradually increased since the publication of the European working group on sarcopenia in this population in 2010⁹. Secondary sarcopenia due to illness or nutritional status may be related to the frailty syndrome¹⁰. Hospitalization for treatment of a disease can lead to a rapid decline in muscle mass and function, triggered by increased inflammation and combined with decreased muscle activity, which can cause some older people to become sarcopenic¹⁰. The term “acute sarcopenia” was used to refer to the acute loss of muscle mass and function associated with hospitalization¹⁰.

Among the most varied forms of muscle training, neuromuscular electrostimulation (NMES) consists of the application of an electric current, of low or medium frequency, over the muscle, aiming at muscle re-education and atrophy prevention¹¹. The NMES application is related to maintaining and increasing muscle strength and endurance, in addition to increased exercise tolerance, improved balance and functionality^{11), (12}. In short, the loss of muscle strength in hospitalized older adults is widely described in the literature^{9), (10} and NMES is a safe and viable therapeutic strategy to be used in the hospital¹³.

Within this context, the objective of this study was to evaluate the effects of NMES on the functionality of frail and pre-frail hospitalized older adults.

METHODOLOGY

This is a randomized clinical trial with older patients admitted to a highly complex hospital, registered under the Brazilian Registry of Clinical Trials (Rebec No. 9xg5qs). All participants signed the Informed Consent Form, and the study was approved by the Research Ethics Committee of the institution under opinion No. 2,642,892.

Casuistry

Older adults were allocated into two groups by means of randomization using the online GraphPad software: control group (CG) and intervention group (IG). The study included older people aged 60 years or over, with a length of stay equal to or greater than two days and equal to or less than 10 days, classified as frail or pre-frail according to the criteria of Fried et al. ⁽¹⁴. Exclusion criteria were: hemodynamically unstable patients; patients with bone fractures that made intervention impossible; patients with neuromuscular diseases; patients unable to obey simple commands; patients using sedation and/or neuromuscular blockers and patients contraindicated to receive NMES.

Procedures

A questionnaire adapted by the authors was applied based on the subjective assessment of the frailty of Fried et al. ⁽¹⁴, which has been used in studies to identify hospital frailty¹⁵,with socioeconomic identification data, evaluation of frailty syndrome, perimeter of the thigh muscles, Medical Research Council (MRC) and sit-to-stand test (STST).

The assessment of quadriceps muscle strength was obtained using the MRC scale, quantifying the degree of muscle strength throughout the range of motion in values ranging from 0 (absence of muscle contraction) to 5 (performs the movement against maximum resistance) ⁽¹⁶. A physical therapist received training and applied the manual muscle strength test, which was standardized in the two groups studied¹⁶. The STST evaluated the strength and resistance of lower limbs. The number of times the patient got up from the chair in 30 seconds was counted without assistance and without hand support¹⁷. In addition, with the patient in the supine position, measurements of the thigh circumference were performed at the midpoint between the inguinal line and the upper edge of the patella¹⁸. These assessments were carried out before and after the NMES protocol.

Both control and intervention groups received assistance from the hospital’s physical therapy service, which consisted of walking, passive stretching exercise, strengthening of lower and upper limbs and kinesiotherapy, according to each patient’s needs¹⁹. The consultations were performed once a day, lasting approximately 20 minutes, making an average of eight physical therapy sessions in both groups.

In the IG, NMES was performed with an Ibramed^® electric stimulator, model Neurodyn II, 4 channels, São Paulo/Brazil. After cleaning the skin, two Arktus^® silicone electrodes, size 5×9 cm, were placed on the quadriceps, the anode being 4 cm above the upper edge of the patella. The cathode positioning was guided by the determination of the motor point on the upper lateral surface of the quadriceps muscle. The motor area of greatest muscle contraction was used to position the cathode^{20), (21}. During electrostimulation, patients were supine, with their knees at 30º of flexion, being encouraged to perform isometric contractions concomitantly with the electrical stimulus¹². All sessions lasted 30 minutes, with a frequency of 50 Hertz (Hz), pulse duration of 300 microseconds, rise time of 1 second, stimulus time (ON) of 5 seconds, descent time of 1 second and time of 10 seconds of relaxation (OFF) ^{(12), (20}. Intensity was adjusted according to the patient’s tolerance, with approximately 100 contractions per session.

Statistical analysis

Microsoft Excel was used to tabulate the data, and the Statistical Package for the Social Sciences (SPSS - version 19) was used for statistical analysis. The Winpepi program (version 11.43) was used To calculate the sample size. The sample size was calculated in eight patients in each group, considering statistical power of 80% and significance level of 5% to detect an average difference between the groups of 2 ± 1.3 repetitions in the sit-to-stand test²¹. The Kolmogorov-Smirnov test was used to analyze the data distribution. In the comparisons between the groups and the pre and post-intervention times, analysis of variance (ANOVA) with repeated measures was used, followed by the Holm-Sidak post-hoc test. Comparisons between groups for body weight, age and BMI were performed using the Student’s t test for independent samples. Categorical variables were analyzed using the chi-square test. Values of p<0.05 were considered statistically significant.

RESULTS

Twenty-four hospitalized older adults from May to September 2018 were evaluated, as Figure 1 shows.

Figure 1
Flowchart of patients and composition of groups

Table 1 shows that the groups are similar in terms of demographic, anthropometric, clinical characteristics and continuous use of medications.

Table 1
Anthropometric and sociodemographic data of the sample

		IG	CG	p
Age (years) (±SD)		71.2±5.6	67.7±6.9	0.27
BMI (kg /m2) (±SD)		27.3±5.1	25.2±4.7	0.39
Height (m) (±SD)		163.8±9.5	161.4±7.1	0.55
Sex				0.77
	Female	3 (37.5%)	4 (44.4%)
	Male	5 (62.5%)	5 (55.6%)
Frailty Assessment				0.85
	Frail	5 (62.5%)	6 (66.6%)
	Pre-frail	3 (37.5%)	3 (33.4%)
Reason for hospitalization				0.27
	Gastrointestinal tract	2 (25%)	1 (11.1%)
	Respiratory	2 (25%)	3 (33.3%)
	Oncological	-	3 (33.3%)
	Cardiological	1 (12.5%)	1 (11.1%)
	Neurological	1 (12.5%)	-
	Renal	2 (25%)	-
Orthopedic		-	1 (11.1%)
Medications in continuous use*				0.31
	Absence	-	1 (11.1%)
	1-2	1 (12.5%)	2 (22.2%)
	3-5	3 (37.5%)	5 (55.6%)
	>5	4 (50.0%)	1 (11.1%)

• IG: intervention group; CG: control group; BMI: muscle mass index; *: amount of medication in continuous use at the time of hospitalization.

Anova revealed significant effects of NMES when compared to the CG for perimetry of the right thigh (p=0.03); for the number of repetitions in the STST (p=0.004); and for quadriceps muscle strength (p=0.01), assessed by the MRC scale, as shown in Table 2.

Table 2
Effects of functional electrical stimulation on muscle strength in hospitalized older adults

		IG			CG		Difference between groups	p
	Pre	Post	∆	Pre	Post	∆
HGS (kg/f)	26.2±7.7	21.6±10.1	5.4±2.9	24.2±6	22.4±7	1.7±3.2	0.8±0.5	0.32
Perimetry D (cm)	46.0±7.67	48.5±6.4	2.5±1.4	44.6±6.7	43.8±7.2	0.7±2.6	4.7±3.3*	0.03*
Perimetry E (cm)	47.2±5	48.3±6.4	1.1±2.8	44.2±6.4	43.7±7	0.5±2.6	4.6±3.2	0.06
STST (number of repetitions)	8.3±2.26	9.6±2.9	1.2±1.4	6.4±1.8	6.0±1.5	0.4±1.3	3.6± 2.5*	0.004*
MRC	4.1±0.64	4.7±7.0	0.6±0	3.5±0.5	3.5±0.5	-	1.2±0.8*	0.01*
Walking speed (m/s)	0.61±0.23	0.75±0.37	0.14±0.29	0.48±0.11	0.46±0.09	0.02±0.07	0.29± 0.2	0.18

• Data presented as mean and standard deviation. IG: intervention group; CG: control group; HGS: hand grip strength; MRC: Medical Research Council; STST: sit and stand test; ∆: intra-group difference; *: difference between groups (p<0.05).

DISCUSSION

The main findings of this study showed increased strength of the lower limbs after NMES protocol in frail and pre-frail hospitalized older adults. The use of NMES proved to be an effective resource in the context of hospital physical therapy applied to Geriatrics. Similarly, other results obtained in other clinical situations, such as chronic obstructive pulmonary disease and heart failure^{13), (22}, reported that a short-term NMES protocol also promoted improvement in muscle strength and exercise tolerance in hospitalized patients.

As far as it is known, this is the first randomized clinical trial that aimed to investigate the effects of NMES in frail and pre-frail hospitalized older adults. Strength gain through NMES can be attributed to increased muscle and neural activation, which, when associated with voluntary contractions, can optimize muscle recruitment arising from NMES¹¹. The association of NMES with kinesiotherapy showed an improvement in the strength of lower limbs and an increase in the ability to walk in hospitalized older women²³. Although an increase in muscle strength is observed after NMES, the length of hospital stay did not differ between the intervention group and the control group, despite the improvement in functional performance in the STST.

Our results showed an increase in the perimetry of the right thigh in the NMES group, when compared to the control. Benavent-Caballer et al. ⁽¹² reported an increase in the cross-sectional area of the rectus femoris muscle after NMES protocol associated with isometric contraction in the elderly. However, other studies do not corroborate our findings^{21), (24}. Studies using more accurate methods, such as magnetic resonance, computed tomography or ultrasonography, may confirm the changes in muscle volume induced by NMES¹².

NMES has the potential to be used especially in individuals who cannot perform intense exercises that guarantee adequate strengthening, such as frail older people and hospitalized patients^{25), (26}. Voluntary isometric contraction should also be requested whenever possible so that there is greater muscle activation. Both resistance training and NMES are effective options for the prevention and treatment of sarcopenia in institutionalized and hospitalized older adults, and are preferably indicated²⁷.

Our results showed an increase in muscle strength and endurance, results evaluated by performance in the STST and corroborating other studies of NMES in hospitalized older adults who used NMES in patients with chronic obstructive pulmonary disease, in the cardiac postoperative period, with osteoarthritis and with severe heart failure^{(130, (21), (27), (28}. The increase in the number of repetitions in the STST of the intervention group suggests an improvement in muscle endurance in a functional movement widely used in daily life. Another result that confirms the strength gain in the NMES group was the improvement in the MRC scores, a scale widely used and currently recommended as a method for diagnosing muscle weakness acquired in intensive care units¹⁶.

A systematic review with meta-analysis showed significant effects of NMES on muscle strength, assessed by the MRC scale in critically ill patients²⁴. Frail older people have a higher risk of hospitalization when compared to other non-frail people, and sarcopenia is closely linked to frailty and hospitalization^{15), (29}. It was observed that frailty is associated with muscle decline, especially in individuals with long periods of hospital stay³⁰. The presence of low mass and muscle function during acute illness is associated with increased health costs, length of stay, rehabilitation costs and the need for institutional care or post-discharge social assistance. In this context, the prevention of acute sarcopenia brings broader economic benefits, as well as benefits to patients¹⁰. Therefore, strategies to reduce adverse events resulting from disuse and hospitalization, such as NMES, can attenuate the loss of muscle mass and improve functionality in hospitalized older adults.

It should be noted that this study has some limitations. We recognize the heterogeneity of subjects at the time of hospitalization and the wide variety of pathologies as a reason for hospitalization. Furthermore, there was no follow-up after the patient was discharged to verify the long-term treatment effectiveness.

CONCLUSION

This study provides evidence from NMES on improving muscle strength of lower limbs in frail and pre-frail hospitalized older adults. These results suggest that NMES can be a useful therapeutic strategy for hospitalized older people.

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  Khandelwal D, Goel A, Kumar U, Gulati V, Narang R, Dey AB. Frailty is associated with longer hospital stay and increased mortality in hospitalized older patients. J Nutr Health Aging. 2012;16(8):732-5. doi: 10.1007/s12603-012-0369-5
  » https://doi.org/10.1007/s12603-012-0369-5

• 5
  Study developed at Hospital São Vicente de Paulo (HSVP) - Passo Fundo (RS), Brazil.
• 6
  Funding source: nothing to declare
• 8
  Approved by the Research Ethics Committee: Protocol No. 2,642,892

Publication Dates

• Publication in this collection
  31 July 2020
• Date of issue
  Apr-Jun 2020

History

• Received
  12 Dec 2018
• Accepted
  14 Apr 2019