Keywords:
Multiple Sclerosis - Aquatic Environment - Resistance Training
Palavras-chave:
Esclerose Múltipla - Ambiente Aquático - Treinamento de Força
INTRODUCTION
Multiple sclerosis (MS) is a chronic autoimmune disease of the central nervous system,
leading to inflammation, degeneration and, ultimately, persistent disability in affected
patients[1]. The chronic and recurrent demyelination in MS evolves with axonal and neuronal
loss and dysfunction of electrical nerve impulse transmission[2]. MS prevalence varies worldwide, with a typical latitudinal grading in which the
disease is more common away from the equatorial line[3]. MS prevalence in Brazil follows this gradient pattern with 1.36 cases/100,000 inhabitants
in the Northeast to 27.2/100,000 inhabitants in the South of the country[4]. The disease typically affects women between 20 and 40 years of age, and presents
with a wide range of neurological symptoms. These symptoms may recover, recur, or
become disabilities. Among these signs and symptoms are motor and sensory deficits,
tremors, decreased coordination, visual impairment, and sphincter dysfunction[5]. Mood and sleep disorders, cognitive dysfunction, and fatigue are also significant
in the lives of people with MS[6].
Measuring disability in MS is challenging. Given the wide variety of signs, symptoms,
and comorbidities that affect patients, it is virtually impossible to measure the
impact of disabilities. No scale covers all possible dysfunctions and their impact,
and neurologists have agreed to maintain the Expanded Disability Scale Score (EDSS)[7] as the standard measure in studies. The EDSS is graded in half points from zero
(normal) to 10 (MS-related death), it is highly dependent on motor function and gait,
and increased EDSS scores can associated with higher levels of fatigue[8].
Physical activity programs have shown to positively influence the lives of patients
with MS[9],[10], especially by reducing fatigue levels. Although a variety of programs have been
proposed, strength training programs show the greatest benefit for people with MS.
Patients can improve strength, reduce fatigue, decrease disease progression, and have
a higher quality of life[11],[12],[13]. Aquatic training has been highly recommended for individuals with MS[14],[15], and aerobic aquatic training programs have shown benefits for these patients since
the 1980s[16].
Recent studies have demonstrated that aerobic aquatic training programs improves walking
ability and ability to get up from a sitting position[17]. In a systematic review, a significant increase in quality of life levels was observed
in MS patients after aerobic aquatic training[18]. These findings demonstrate that prescribing exercise programs is a non-pharmacological
way to improve physical performance and quality of life. Despite the findings in the
literature on the benefits of aquatic aerobic training, a determining variable for
maintaining of functional capacities is strength, and there is currently a gap regarding
the benefits of aquatic strength training and the form of individualized prescription
of these model-training programs for patients in different conditions.
The aim of the present study was to investigate the effects of associating an aquatic
and strength training program specially designed for individuals with MS.
METHODS
Subjects
The Ethics and Research Committee of the Federal University of São Paulo approved
the current project. A convenience sample of 26 patients with MS diagnosed and treated
in the coastal region of the state of São Paulo, Brazil, was enrolled. At the time
of the project, no patient exercised regularly and a team of neurologists followed
all volunteers. The patients enrolled voluntarily and the group consisted of 22 women
and seven men. Participants were medically examined prior to participation. Maximum
disability at the time of enrollment was defined as EDSS<6.0 (able to walk even if
the aid of a cane was required). All volunteers signed a free informed consent form
before entering the trial.
Materials, participants and procedure
Body weight and height were used to calculate the body mass index (BMI). Percent body
fat was calculated through a standard protocol[19].
Physical tests
The tests were performed in two distinct time points: before and after a 12-week intervention
program of aquatic strength training. The tests consisted of:
-
Aerobic performance: assessed by the six-minute walk test performed in a 30-meter
hall with a demarcation every three meters and two cones at the ends[20],[21],[22].
-
Strength of upper limbs: assessed by the handgrip test. Subjects were evaluated seated
in a chair with the spine erect, knees bent at 90 degrees and shoulders in an anatomical
position. The elbow remained flexed at 90 degrees, with the forearm in a neutral grip
position, with the possibility to bend it up to 30 degrees. The subject was then instructed
to grasp the dynamometer as hard as possible for five seconds. The test is repeated
three times with a 1-minute interval between each repetition. The highest value obtained
for the dominant and non-dominant hand was recorded[23],[24].
-
Activities of daily living: these were assessed by getting up from the floor; sitting
and getting up from a chair and walking a short distance; walking up and down 15 steps;
and putting on socks[25].
-
Fatigue: assessed by the Impact of Fatigue and Severity of Fatigue questionnaires[26].
Aquatic strength training program
The protocol consisted of three times a week frequency for 12 weeks with 50 minutes
per session. Five minutes of warm-up with aerobic and coordination exercises, forty
minutes of strength training exercises. The routine was split into: Monday - exercises
for the front part of the body, Wednesday - exercises for the back part of the body.
In the last five minutes the subjects performed cool-down exercises. The program was
performed in a 25-m swimming pool, with a water depth of 1.5 m and average temperature
of 29°C, located in the Universidade Metropolitana de Santos. The load control for
the strength exercises was made by the number of repetitions in a 30-second time test;
the load used for the training sessions during the 12 weeks was between 50 and 80%
of the maximum. The load control followed a non-linear periodization, increasing the
load in three weeks and decreasing it in the fourth week ([Figure 1]). The interval between sets was 30 seconds, with cyclic exercises. The training
protocol consisted of eight exercises, four exercises for the upper body and four
exercises for the low body.
All training sessions were prescribed and accompanied by two physical education instructors.
Figure 1 Load control model for all the exercises applied in series of 30 seconds. Repetitions
were established based on the number of maximum repetitions performed in 30 seconds.
The model includes a weekly goal and intensity performed by patients.
Statistical analysis
After confirming that the data was normally distributed with the Shapiro-Wilk test,
the Student’s t-test was used to compare the pre- and post-intervention time points. Cohen’s test
was used for assessing the effect size. The level of significance was set at p≤0.05
with a 95% confidence interval (95%CI).
RESULTS
Anthropometric characteristics of all patients and their degree of disability are
shown in [Table 1]. Women had higher body fat levels, as well as higher number of relapses and disability.
Table 1
Physical characteristics of volunteers with multiple sclerosis (mean±SD).
|
Characteristic
|
Female
|
Male
|
General
|
|
EDSS
|
2.2±1.3
|
1.8±1.5
|
2.1±1.3
|
|
Number of relapses
|
3.8±5.4
|
1.5±1.9
|
3.4±4.9
|
|
Weight (kg)
|
72.5±17.7
|
74.8±13.5
|
72.9±16.7
|
|
Height (cm)
|
1.67±0.1
|
1.78±0.1
|
1.65±0.1
|
|
BMI
|
27.4±6.2
|
23.4±3.0
|
26.6±5.9
|
|
% body fat
|
31.4±6.3
|
17.4±5.2
|
28.5±8.3
|
|
Weight body fat (kg)
|
23.6±10.0
|
13.5±5.5
|
21.5±10.1
|
|
Lean muscle mass (kg)
|
48.3±8.8
|
61.1±8.1
|
51.0±10.0
|
SD: standard deviation; EDSS: Expanded Disability Scale Score; BMI: body mass index.
[Table 2] shows the results of physical tests before and after the training program.
Table 2
Results (mean±SD), absolute difference, relative difference and comparison between
the pre- and post-intervention time points for all tests.
|
|
Pre-int.
|
Post-int.
|
Abs
|
Rel
|
p-value
|
Cohen’s d
|
|
6-minute walk (meters)
|
478.3±117.3
|
557.4±119.3
|
79.1±68.7
|
19%
|
0.00
|
0.66
|
|
Dom. Hand Grip (lb)
|
67.1±24.9
|
70.3±22.5
|
3.2±6.5
|
8%
|
0.02
|
0.13
|
|
Non. D. Hand Grip (lb)
|
60.4±19.9
|
65.7±17.3
|
5.2±7.5
|
12%
|
0.00
|
0.28
|
|
Getting up (seconds)
|
6.9±4.4
|
4.4±2.5
|
2.4±2.8
|
-26%
|
0.00
|
0.70
|
|
Sit and get up (seconds)
|
52.8±19.6
|
37.2±15.3
|
15.5±9.4
|
-29%
|
0.00
|
0.89
|
|
Up15 steps (seconds)
|
10.3±4.7
|
8.4±4.1
|
1.8±2.0
|
-16%
|
0.00
|
0.42
|
|
Down 15 steps (seconds)
|
10.7±6.2
|
8.2±4.9
|
2.5±2.2
|
-22%
|
0.00
|
0.45
|
|
Putting socks (seconds)
|
13.9±9.4
|
10.8±8.1
|
3.1±4.8
|
-20%
|
0.00
|
0.35
|
|
Severity of fatigue (points)
|
39.2±18.3
|
32.1±16.8
|
7.5±13.0
|
-12%
|
0.01
|
0.40
|
|
Impact of fatigue (points)
|
47.7±19.6
|
38.4±21.8
|
9.3±16.2
|
-20%
|
0.01
|
0.44
|
SD: standard deviation; Pre-int.: pre-intervention; Post-int.: post-intervention;
Abs: absolute difference; Rel: relative difference; 6-minute walk: 6-minute walk test
in meters; Dom. Hand Grip: dominant hand grip test in Newton’s; Non. D. Hand Grip:
non-dominant hand grip test in Newton’s; Get up: getting up from the floor; sit and
get up: sitting and getting up from a chair and moving a short distance; Up15 steps:
walking up 15 steps; Down 15 steps: walking down 15 steps in seconds; Putting socks:
putting on socks in seconds; Impact of fatigue: impact and severity of fatigue in
scores.
DISCUSSION
In the present study, volunteers significantly improved their performance in all tests
and reduced the time required to perform all functional tests (getting up from the
floor, sitting and getting up from a chair and walking a short distance, walking up
15 steps, walking down 15 steps, and putting on socks). Fatigue levels decreased.
There was an improvement in handgrip strength, which relates to upper limb strength
and is extremely important for the patient to perform daily tasks such as carrying
objects. For the physical performance tests, the improvements varied from 16 to 29%.
These tests are related to the activities of daily living, such as getting up from
a chair and picking up an object in another room, which are closely associated with
patients’ physical independence, and therefore, with their quality of life levels.
The decrease in fatigue levels post-intervention is extremely important, since fatigue
is present in most patients with MS and is one of the main disabling factors of the
disease. Finally, patients increased the distance covered in the six-minute walk test.
This test is commonly used to measure the aerobic conditioning and gait mobility of
patients, and findings demonstrated that even though the patients performed aquatic
strength training, their aerobic fitness was also improved. Taken together, the results
confirm that aquatic strength training can be a non-pharmacological alternative for
patients with MS.
The results of the six-minute walk test are similar to those of other studies[20] showing the beneficial effects of an aquatic training program. The good response
of strength training programs are related to the activation of upper agonist muscles
and of lower antagonist muscles[27],[28]. As previously shown by other authors, our results indicate that higher strength
levels may ultimately be responsible for improved walking capacity and decreased fatigue
levels[11],[15],[29]. Strength training with weights showed similar improvements to the present study.
A study investigating direct and contralateral strength training in patients with
multiple sclerosis for 6 weeks found 16.5% improvement in walking speed[30], data very similar to the present study, which found a 17% improvement in walking
speed. A recent study showed improvement in the walking speed after 24 weeks of strength
training combined with cognitive exercises, corroborating the present findings in
the 6-minute walk test[31].
The high level of fatigue common in patients with MS may limit daily activities. Apart
from a small effect of amantadine in some cases, no drug intervention seems to improve
this situation[32]. On the other hand, aerobic training and strength training programs seem to positively
affect this disabling MS symptom[33],[34],[35]. Two recent systematic reviews demonstrated the benefits of this type of programs
in patients with MS[11],[15]. The aquatic strength training is safe and effective in MS, since high intensity
training can be performed with minimal risk of lesions[35], low post-exercise pain[36], and better control of body temperature[37]. High intensities on aquatic strength training promote an increase in fatigue tolerance
and a decrease in perceived effort in daily activities[34].
In conclusion, aquatic strength training is an effective non-pharmacological strategy
to increase physical functional capacities associated to quality of life of patients
with MS. The practical applications of this study is that physicians accompanying
patients with multiple sclerosis can include guided aquatic strength training in their
prescriptions.
