Rev Bras Fisiol Exerc 2021;19(1):16-23
doi: 10.33233/rbfe.v19i1.3905
ORIGINAL
ARTICLE
Analysis
of glycemic safety of a moderate-intensity resistance exercise session in
patients with diabetes type 1
Leandro Paim da Cruz
Carvalho¹, Samira Socorro Nunes de Souza², Djenane
Cristovam Souza², Flávio de Souza Araujo3, Ferdinando Oliveira
Carvalho4, José Fernando Vila Nova de Moraes4, Jorge Luiz
de Brito Gomes4
1Especialista,
Universidade Federal do Vale do São Francisco, 2Discente,
Universidade Federal do Vale do São Francisco, 3Mestre, Universidade
Federal do Vale do São Francisco, 4D.Sc,
Universidade Federal Do Vale do São Francisco
Received
2020 Jan 10; accepted 2020 Feb 10
Corresponding
author: Leandro Paim da Cruz
Carvalho
Leandro Paim da Cruz
Carvalho: leandroopaim@hotmail.com
Samira Socorro Nunes de
Souza: samira.nunes@hotmail.com
Djenane Cristovam Souza:
janacristovam@yahoo.com.br
Flávio de Souza Araujo: araujo.Fsouza@gmail.com
Ferdinando Oliveira
Carvalho: ferdinando.carvalho@univasf.edu.br
José Fernando Vila Nova
de Moraes: josefernando.moraes@univasf.edu.br
Jorge Luiz de Brito
Gomes: jorge.brito@univasf.edu.br
Abstract
Introduction: Type 1 diabetes is an autoimmune disease that results in the destruction
of pancreatic beta cells, implying the use of insulin therapy to maintain
adequate blood glucose levels. When stimulated by physical exercise, glycemic
homeostasis becomes impaired, providing complications in the daily lives of
this population, constituting a barrier to physical exercise practice. Objective:
To evaluate the glycemic safety of a Resistance exercise session of moderate
intensity in people with type 1 diabetes. Methods: 12 people with type 1
diabetes (7 male), performed a resistance exercise session of moderate
intensity at 60% of 1 RM consisting of 7 exercises. Capillary blood glucose was
assessed at the pre-session (GP), immediately after (G IA) and 20 minutes after
(G 20). ANOVA for repeated measures was performed (p < 0.05). Results:
In the absolute values of glycemia, no significant differences were found (P =
0.061). However, when checking the delta blood glucose variation, a difference
was found between G IA and G20 vs GP (P < 0.05). Clinically important
reductions above 20 mg/dl (PI: ~ 37 mg/dl; 20P: ~ 45 mg/dl) without providing
hypoglycemia. Conclusion: A moderate-intensity resistance exercise
session proved to be safe from a glycemic point of view in people with type 1
diabetes.
Keywords: diabetes mellitus type 1; resistance training; exercise.
Resumo
Análise da segurança
glicêmica de uma sessão de exercício resistido de intensidade moderada em
pessoas com diabetes tipo 1
Introdução: A diabetes tipo 1 é
uma doença autoimune que resulta na destruição das células beta pancreáticas,
implicando no uso de insulinoterapia para manter níveis adequados de glicemia.
Diante do estímulo do exercício físico, a homeostase glicêmica torna-se
prejudicada, podendo incidir em complicações como hipoglicemia. Tais
repercussões proporcionam empecilhos no dia a dia dessa população, constituindo
uma barreira para prática de exercícios físicos. Objetivo: Avaliar a
segurança glicêmica de uma sessão de exercício resistido de intensidade
moderada em pessoas com diabetes tipo 1. Métodos: 12 pessoas com diabetes
tipo 1 (7 homens) realizaram uma sessão de exercício resistido de intensidade
moderada a 60% de 1 RM composta por 7 exercícios. A glicemia capilar foi
avaliada no momento pré-sessão (GP), imediatamente
após (G IP) e 20 minutos após (G 20). ANOVA para medidas repetidas foi
realizada (p < 0.05). Resultados: Nos valores absolutos de glicemia
não foram encontradas diferenças significativas (P = 0,061). Contudo, ao
verificar o delta variação da glicemia foi encontrada diferença entre G IP e
G20 vs. GP (P < 0,05). Reduções clinicamente importantes acima de 20 mg/dl
(IP: ~37 mg/dl; 20P: ~45 mg/dl) sem proporcionar hipoglicemias. Conclusão:
Uma sessão de exercício resistido de intensidade moderada se mostrou segura do
ponto de vista glicêmico em pessoas com diabetes tipo 1.
Palavras-chave: diabetes mellitus
tipo 1; treinamento de resistência; exercício.
Type 1 diabetes is a pathology caused by the progressive destruction of
pancreatic beta cells. As consequence, the person with diabetes starts to
depend on insulin therapy to control hyperglycemia [1]. Complications of the
disease can present in acute form, such as hypoglycemia and diabetic
ketoacidosis [2,3] or in a chronic form, such as cardiomyopathy associated with
diabetes, nephropathy, retinopathy and peripheral neuropathy [4,5].
In healthy individuals, glycemic homeostasis in maintained by
fast-acting hormones (Insulin, glucagon, adrenaline and noradrenaline) and slow
and/or permissive hormones (Cortisol, GH and thyroid hormones T3 and T4) [6].
By stimulating physical exercise, there is a reduction in insulin action and a
concomitant increase in the action of glucagon, promoting degradation of
hepatic glycogen and release of glucose into the bloodstream for later uptake
by active muscles [7]. Due to the type 1 diabetic person’s dependence on the
application of exogenous insulin, this control becomes impaired, increasing the
risk of hypoglycemia (blood glucose < 70 mg/dl) during or after physical
exercise [8,9].
The literature has pointed out the beneficial effects of physical
training in people with type 1 diabetes. In addition to the physiological
benefits, such as increased sensitivity to insulin action and glucose uptake
through signaling induced by muscle contraction [10-12], psychological and
social benefits also stand out, providing a lifestyle favorable to healthy
habits [13]. However, despite the benefits promoted by regular physical
exercise, many of these people avoid getting involved in the practice of
physical training fearing possible episodes of hypoglycemia induced by
exercise; this fear is one of the biggest barriers to the practice of physical
activity in this population [14]. That occurs because during a hypoglycemic
crisis, the individual is affected by symptoms of malaise, such as sweating,
mental confusion, lethargy, and if left untreated, the condition can progress
to coma and even death [15].
Due to the benefits of physical exercise, its prescription becomes a
potent aid for glycemic control in type 1 diabetic people, and resistance
exercise, as it is a widespread and easily accessible training modality,
presents itself as an interesting alternative complementary therapy [16]. Thus,
the present study aimed to verify the glycemic safety of a moderate intensity
resistance exercise session in type 1 diabetic people.
An experimental study with 12 type 1 diabetic people (7 male), age 29,8
± 7,4 years, height 1,69 ± 0,09 m, body mass 70,9 ± 16,8 kg, body mass index
25,2 ± 4,4 kg/m² was performed. All participants were regular in the extension project
“Physical exercise as sugar diary” offered by the collegiate of physical
education of the Federal University of San Francisco Valley (CEFIS-UNIVASF) – Petrolina/PE. The free and informed consent form was
registered at The Research Ethics Committee of UNIVASF under the protocol
number: 3.349.261 and this study approved.
The following inclusion criteria were adopted: Female and male type 1
people over 18 years and who do not have medical restrictions for physical
exercise or any type of secondary diseases that may be aggravated due to
research participation (secondary diseases that have been already diagnosed by
the physician responsible for each diabetic; eg,
peripheral and/or central vasculopathies, retinopathy and amputations).
Participants were excluded from the study if they did not finish the session
and or suffered any type of osteomyoarticular injury
that prevented the practice of physical exercises or at the request of the
physician responsible for everyone outside the scope of the research.
Study
design
Two days before the resistance exercise session, the individuals
underwent an assessment of anthropometric measurements (body mass, height and
perimeters), body composition (skinfolds) and abdominal resistance test. Then,
a 1RM estimation test was performed to measure the training load in each of the
six exercises that would later be performed in the session (bench press,
horizontal leg press, biceps curl on the low pulley, extension chair, machine
development, adductor chair and the abdominal rectus solo - performed from the
abdominal resistance test). Based on Brzycki's
formula [17], 60% of 1RM of each exercise was determined for the training
session.
Subsequently, on the day of the training session, when participants
arrived at the weight training laboratory at the Federal University of San
Francisco Valley – Petrolina/PE, the individuals were
taken to a comfortable chair where they sat at rest for 10 minutes before the
measurement of capillary blood glucose and blood pressure and, subsequently,
they were released for the weight training session. The individuals underwent
the training session with an approximate duration of 30 minutes, and, at the
end, immediately seated in the chair and a new measurement of blood glucose and
blood pressure was performed. After another 20 minutes of sitting at rest, a
last measurement of blood glucose and blood pressure was performed, and the
individuals were released.
Body
composition and anthropometrics variables
To verify the individuals' body mass and height, a digital weight
balance with stadiometer, Lider brand, model LD-1050,
was used. The individuals were positioned on the weight balance, with their
backs to the wall, feet together and bare. The anthropometric tape of the Sanny brand, model TR-4010 was used to evaluate body
perimeters and the clinical adipometer of the Sanny brand was used for skinfold measurements.
Blood
glucose, arterial blood pressure and heart rate
The heart rate was monitored during the session using a Polar cardiac
monitor, model FT1. Subsequently, blood pressure was measured using a digital
arm blood pressure meter of the OMRON brand, model HEM-7113 following the
recommendations of the 7th guideline for arterial hypertension of the Brazilian
Society of Cardiology [18]. Capillary blood glucose was measured by a qualified
nurse at the pre-session moment (after 10 minutes of rest), immediately after
and 20 minutes after the session using a Glucometer and lancets (Active Accu Check Roche), following the recommendations of the
Society Brazilian Diabetes [8].
Training
session
The weight training session was conducted and supervised by a qualified
Physical Education professional. Composed of 3 sets of 10-12 repetitions at 60%
of 1RM of the seven exercises previously described, with an interval of 50-60
seconds between each set, and a cadence of 3s (1.5 for eccentric contraction
and 1.5 for concentric contraction). Ultra-fast insulin before the last
pre-session meal was reduced according to guidelines [8].
Statistical
analysis
The data were analyzed using the Graph Pad (3.0) software. The
Shapiro-Wilk normality test and the ANOVA test for repeated measures were
performed (p < 0.05). The minimum detectable difference was performed to
identify important changes in blood glucose, according to a previous study
[19].
Analyzing the absolute blood glucose values, no statistically
significant differences were found between the pre-session moments, immediately
after and 20 minutes after the session (P = 0.061). However, when checking the
delta glycemia variation between the three moments, a statistically significant
difference was found between the moment immediately after and the moment 20
minutes post-session, in relation to rest (P < 0.05). The description of the
study participants is shown in table I.
Table
I - Sample data description
BMI = Body mass index; HR = Heart rate; BPM = Beats per minute;
SBP = Systolic blood pressure; DBP = Diastolic blood pressure;
SSF = Somatory of skin folds;
DT = Diagnosis time
The following are the glycemic changes in the moments pre, immediately
after and 20 min after a resistance exercise session of moderate intensity
(Figure 1). Frame A shows glycemic safety without providing hypoglycemia. Frame
B, in turn, reveals the significant differences in the variation delta in relation
to rest (p < 0.05). In addition, the minimum detectable difference was
verified after the session and after 20 minutes of the session, presenting
clinical importance at these moments.
*Significant
difference in relation to rest and MDD > 19.2 mg/dl with a clinically
important reduction in relation to rest
Figure
1 - Absolute and relative variation (Δ)
of capillary glycemia at rest (pre), immediately after (G IA) and 20 minutes
after (G 20) a weight training session of moderate intensity in type 1 diabetic
individuals
The aim of the present study was to assess the glycemic safety of a
moderate-intensity resistance exercise session in people with type 1 diabetes.
The main findings show that the variation in glycemic reduction (Δ) between
the moments of the session was significant for the moment immediately after (G
IP) and 20 minutes after the session (G 20), which correspond to a decrease of
17.8% and 21.7% respectively. Still, a clinically important reduction was found
for the participants after a resistance exercise session with moderate
intensity, without providing hypoglycemia
It is known that physical exercise improves insulin signaling and
increases the uptake of glucose by the muscle in ways independent of insulin
action. The muscular contraction itself, from the imbalance in the AMP/ATP
balance and calcium signaling, promotes the stimulus for the activation and
translocation of the GLUT-4 vesicles to the plasma membrane, allowing glucose
to enter the intracellular medium [20]. The consumption of glucose, free fatty
acids and other substrates increases during physical exercise, which may
enhance the action of insulin, and the proportion of use of these substrates
will depend on the intensity and duration of physical exercise. Thus, it is
necessary that the dose of fast-acting insulin be adjusted before exercise,
considering the characteristic and duration of the training session [21].
Intensity is an important factor and can modulate the glycemic response
of individuals with diabetes differently. In the study by Cruz et al.
[22], the authors demonstrated that light intensity in resistance exercise (40%
of 1 RM) decreased glycemic levels in type 2 diabetic women for a period of 24
hours when compared to a high intensity session (80% of 1RM) and a control
session. In the study by Yardley et al. [23] with type 1 diabetic
people, which evaluated the glycemic response for 24 hours between aerobic
exercise (60% VO2max) and resistance exercise (seven exercises with
three sets of eight maximum repetitions), it was shown that resistance exercise
caused a lower glycemic reduction during the session, however, over the 24
hours, it was associated with more prolonged reductions. Such behavior is like
that found by Shetty et al. [7] who, when comparing different
intensities of aerobic exercise (35, 50, 65 and 80% VO2 peak),
demonstrated that the increase in intensity above 50% of VO2 peak leads to
higher glycemic levels.
The results of the present study demonstrated a drop in
blood glucose throughout the session of moderate resistance exercise. However,
in absolute values, there was a large intra-subject variation in glycemic
behavior. This was already expected, since factors such as time of diagnosis,
food and water intake influence glycemic control [21,24]. In addition, in this
population, the genetic factor involved in the pathogenesis of the disease is
very heterogeneous, with more than 60 gene polymorphisms providing an increased
risk for the onset of the disease. Some authors even claim that each type 1
diabetic patient has their own type of diabetes [25]. Even despite such
factors, there were no hypoglycemia.
In addition to the aforementioned factors, physically active type 1
diabetic people have a better metabolic profile than their sedentary peers
[26], and the pathology should not be considered as an impediment to the
practice of physical exercise. On the contrary, exercise should be encouraged
in this population, requiring only precautions for greater safety [9]. As
verified in the present study, only one session of resistance physical
exercises can help to control the acute glycemic variation with clinical
importance for practitioners.
Finally, the present study had some limitations, such as the lack of
dietary control in the 24 hours prior to the session, the short post-session
evaluation period (only 20 minutes) and the absence of a control group.
However, the results have a high practical application, since the performance
of a session of moderate resistance exercise with alternating exercises by
segments can help regulate glucose without causing hypoglycemia and thus reduce
the possible fear of the diabetic person of suffering hypoglycemia during and
after physical exercise.
In conclusion, a session of resistance exercise of moderate intensity
proved to be safe from the glycemic point of view in people with type 1
diabetes. In addition, it promoted a reduction in blood glucose values in
relation to baseline values that varied between 17.8% and 21.7% with clinically
important changes, which may be beneficial in the long term for this
population.
The authors of this work would like to thank PROEX UNIVASF, the FACEPE
development agency, the Bioanalises laboratory, the
city hall of Petrolina/PE and Ariel Custódio de Oliveira II for their collaboration.