Glycative Stress Research
Online edition : ISSN 2188-3610
Print edition : ISSN 2188-3602
Received : June 17, 2020
Accepted : August 18, 2020
Published online : September 30, 2020
doi:10.24659/gsr.7. 3_258

Original article

Amelioration of postprandial hyperglycemia by exercise withultra-soft rubber bands: A non-crossover test.
Zheng Tian 1), Masayuki Yagi 1), Mari Ogura 1, 2), Takeshi Terasaka 3, 4), Shoji Kuwabara 4,6),
Toshiyo Jinden 4), Yoshikazu Yonei 1, 5)1) Anti-Aging Medical Research Center and Glycative Stress Research Center, Faculty of Life and Medical Sciences,
Doshisha University, Kyoto, Japan2) Kyoto Bunkyo Junior College, Kyoto, Japan3) Kyowa Rubber Co. Ltd., Osaka, Japan
4) EWP Co. Ltd., Shimane, Japan
5) Nippon Kokan Hospital, Kawasaki, Kanagawa, Japan6) Muikaichi Hospilal, Shimane, Japan

Abstract

Purpose: Postprandial hyperglycemia induces a chain reaction of aldehyde production, thus causing vascular endothelial
cell damage which greatly increases the risk of cerebral cardiovascular disease. In this study, we verified the postprandial
hyperglycemia improvement effect of a resistance exercise using a rubber band after eating.
Methods: 66 men and women with no regular exercise habits were recruited, followed by selecting in the order of highfasting blood glucose, 12 subjects (7 males, 5 females, 55.3 ± 5.2 years old) were analyzed. After ingesting cooked rice (200g), three types of resistance exercises using a super soft rubber band (large or small size) were performed, and blood glucose
and insulin levels were measured. The test was non-cross-over, and every week, control (no exercise), GB10 (large, 10 min, 35kcal), GS10 (small, 10 min, 35 kcal), GS6 (small, 16 min, 21 kcal) of each group was performed.
Results: Compared with the control, GS10 showed significantly lower blood glucose levels at 30 min, while GS6 at 30 and
90 min (p < 0.05). There were no differences between groups in glucose AUC, iAUC, Cmax, Tmax, HOMA-IR. The insulinlevels of GB10, GS10, and GS6 were significantly higher than those of the control at 60 min ( p < 0.05). The low order offasting blood glucose, Cmax and the high order of insulin AUC were GS6 group (4th), GS10 group (3rd), GB10 group (2nd),
control (1st), and indicating accumulative effect of the exercise. There were no adverse events.
Conclusion: Middle-aged people with insufficient physical activity performed resistance exercises with this band for 6 to 10
min after eating, leading to reduced postprandial hyperglycemia and an increase in glucose-responsive insulin secretion. In
addition, an accumulation effect was observed, suggesting that glycative stress may be improved by continuing this exercise.

KEY WORDS: postprandial hyperglycemia, insulin secretion, glucose tolerance, resistance training, glucose spikes,

		ultra-soft rubber bandContact Address: Professor Yoshikazu Yonei, MD, PhD
Anti-Aging Medical Research Center, Graduate School of Life andMedical Sciences, Doshisha University
1- 3 Tatara Miyakodani, Kyotanabe, Kyoto 610-0394, Japan
TEL / FAX: +81-774-65-6394 e-mail: yyonei@mail. doshisha.ac. jp
Co-authors; Tian Z, tomtomtom1990@hotmail.com;
Yagi M, myagi@mail.doshisha.ac.jp; Ogura M, m-ogura@po.kbu.ac.jp;
Terasaka T, t-terasaka@kyouwa-r.com; Kuwabara S, shoji.kuwabara@ewp.ai;
Jinden T, jinden@e-wellness-p.co. jp_ 258 _

Glycative Stress Research 2020; 7 ( 3) : 258-267(c) Society for Glycative Stress ResearchGlycative Stress Research

Introduction

The major causes of cerebral cardiovascular disease,which is the top cause of death in Japanese, are high glycative
stress, i.e., impaired glucose tolerance, dyslipidemia, andhigh blood pressure that causes mechanical damage to thevascular endothelium. These factors are accumulated in themetabolic syndrome triggered by visceral obesity and arealso a major risk factor for type 2 diabetes mellitus (T2DM).
Among the Japanese aged 40 to 70, 19.4 million are withmetabolic syndrome or its high-risk group 1, 2). Regarding thenumber of diabetic patients, in the Ministry of Health, Laborand Welfare “Overview of 2017 Patient Survey ”, it reported
that it increased by 123,000 from the previous survey in2014, reaching a record high of 3,289,000 3). The rapid
increase in the number of metabolic syndrome and T2DM
cases has become a major social problem.
As a measure against this problem, it is important toimprove lifestyle habits from the earliest stage as much as
possible, that is, to prevent progression from the stage ofmild glucose intolerance to the next stage. Postprandial
hyperglycemia is referred to as glucose spikes 4, 5) which
induce production of various aldehydes by a chain reaction(aldehyde spark) 6), thus causing vascular endothelial cell
damage, which is a risk factor of cerebral cardiovasculardisease. In this study, we have chosen short-term muscle load
exercise using a rubber band and verified the amelioration
effect on postprandial hyperglycemia.

Methods
Subjects

The subjects were healthy men and women aged from 45
to 65 years without exercise habits and 66 participants wereselected. Physical examination, tests of hematology, generalblood chemistry, urinalysis, electrocardiography, and doctor
interviews were performed as a prior examination (screening:
SCR) on the recruiters. Finally, 14 patients were selected
in descending order of fasting blood glucose (FBG) levelfrom those who met the selection criteria and did not violate
the exclusion criteria and were judged to be appropriate toparticipate in the study based on the investigator's judgment.
The selection criteria are shown below.
1) Men and women 40 to 60 years old at the time when theconsent for participation in the study was obtained.
2) Healthy persons without chronic physical illness
including skin diseases.
3) Persons with the ability to give consent after receiving
an adequate explanation of the purpose and content of
the study, and who volunteer to participate on their own
accord after proper understanding and provide a writtenconsent to participate in this study.
4) Persons who can come on the designated examination
date to undergo examination.
5) Persons determined to be suitable as a subject of thisstudy by the principal investigator.
The exclusion criteria are shown below.
1) Persons determined to be unsuitable as a subject of thisstudy by the principal investigator.
2) Persons with a history of, or currently suffering frommental illness, sleep disorders, hypertension, diabetes
mellitus, dyslipidemia, or a serious illness.
3) Persons who have been taking drugs for the treatmentof a disease for the past one month (excluding thosewith a history of taking temporary-relief medication forheadaches, menstrual pain, and colds)
4) Persons with a history of, or currently suffering from asevere disease of the liver, kidney, heart, lungs, digestiveorgans, or hematologic disease.
5) Persons with a history of, or currently suffering from asevere disease of the gastrointestinal tract.
6) Persons who have an abnormality on electrocardiography.
7) Persons with a body mass index (BMI) of less than 18.5kg/m2 or more than 30 kg/m2.
8) Persons who have donated 200 ml of blood in the past one
month, or over 400 ml within the past 3 months.
9) Persons with severe anemia.
10) Persons who have difficulty collecting blood as scheduled.
11) Persons with daily exercise habits.
12) Persons who have difficulty in exercising for 10 min.
13) Persons who consume more than 60 g/day of alcohol on
average.
14) Persons who may change their lifestyle during the test, i.e.,
long-term travel.
15) Currently and within the past 3 months, persons who havea habit of continuously taking functionally labeled foods/
health foods that are associated with glucose metabolism,
and those who plan to take them during the study period.
16) Women pregnant, lactating or possibly pregnant.
17) Persons who are currently participating in other humanclinical trials, and those who have participated in otherhuman clinical trials within the past 3 months.
18) Persons who have been determined by the principal
investigator as not suitable to be a subject of this study.

Figure 1 shows the change in the number of test subjects.
The 12 subjects (7 men, 5 women) analyzed were 55.3 ± 5.2
years (males: 55.0 ± 5.9, females; 55.6 ± 4.7 years).

Test design
As a non-intersecting type repeat test, this test performed
postprandial loading of the following three types of exercise
and compared the transion of glucose and insulin levels with
control.
· GB10 group: Exercise full set using a large band (10 min).
· GS10 group: Exercise full set using a small band (10 min).
· GS6 group: Exercise half set using a small band (6 min).
The test schedule is shown in Fig. 2. There was a one-weekwashout period between each visit.
The ultra-soft rubber band used is made by Kyowa
Rubber Co., Ltd. (Hirakata, Osaka, Japan), and the siliconmaterial is specially processed to be super-soft and intended
to easily move the muscle without applying a large load. The
large type had a thickness of 2 mm and the perimeter was
about 1,600 mm, and the small type had a thickness of 2 mm
and the perimeter was about 500 mm. The exercises were
performed by passing a band through the arms and legs, withthe trainer instructing the subject in the standing and sitting
positions.

_ 259 _

Effects of Sub-Aleurone-Remaining Rinse-Free Rice
19

Fig. 1Changes in the number of test subjects.

Fig. 1. Changes in the number of test subjects.
Fig.
 2. Test schedule.
 2. Test schedule.
Fig.

20
20



SCR, screening; WO, washu out; Exam, examination.

SCR, screening; WO, washu out; Exam, examination.

SCR, screening; WO, washu out; Exam, examination.

Fig. 2. Test schedule.

_ 260 _



Glycative Stress Research

Evaluation iteme

Table 1. Loaded rice.

Blood glucose and insulin were measured before, 30 min
after loading, 60 min after loading, 90 min after loading,and 120 min after loading (5 times). The main evaluation
items were changes in measured values, the amount of
increase or decrease relative to before loading meal intake(0 min), the area under the curve (AUC) calculated using thetrapezoidal method, incremental AUC (iAUC) under which
the negative area is added as a negative value, Cmax which
was the maximum blood concentration, and Tmax which
was the maximum blood concentration reaching time after
loading rice. HOMA-IR (homeostasis model assessmentof insulin resistance) using the calculated value of fasting
insulin level (μU/mL) x FBG level (mg/dL)/405 was used as
the secondary endpoint. The test period was from February
to March 2020.

Ingredient

Steamed rice (200 g)
294 kcalCalorie

4.2 g

Protein0g

Fat

67.8 gCarbohydrate

0g

SodiumTable 2. Seasoning ingredient.
Ingredients

Salted sesame (3 g)Calorie
ProteinPrior examination
Anthropometric measurements (height/weight/bodyfat percentage/BMI), blood pressure/pulse measurement,
electrocardiography, doctor interviews, general urine tests,
peripheral blood tests and biochemical tests using blood
samples were performed. The items to be implemented
included white blood cell count (WBC), red blood cell count(RBC), hemoglobin amount (Hb), hematocrit value (Ht),average red blood cell volume (MCV), average red blood
cell hemoglobin amount (MCH), average red blood cell
pigment concentration (MCHC), platelet count (Plt), total
protein (TP), albumin quantification, urea nitrogen (BUN),
creatinine (CRE), uric acid (UA), aspartate aminotransferase(AST), alanine aminotransferase (ALT), γ -glutamyltranspeptidase (γ -GTP), alkaline phosphatase (ALP),
lactate dehydrogenase (LDH), creatinine kinase (CPK), totalcholesterol (TC), triglyceride (TG), low-density lipoproteincholesterol (LDL- C), high-density lipoprotein cholesterol(HDL- C), non-HDL cholesterol * calculated value, total
bilirubin (T-Bil), FBG, HbA1c [NGSP], and immunereactive insulin (IRI). The test using the blood sample wasmeasured by Health Science Institute Co., Ltd. (Yokohama,
Kanagawa, Japan).

Rice load: How to adjust and ingest loaded meals
The test was conducted according to a uniform protocol by
the Japan Glycemic Index (GI) Study Group 8). Commerciallyavailable packaged steamed rice “ Sato no Gohan, Niigata
Koshihikari 200 g” (Sato Food Industry, Niigata, Japan) wasused. The packed rice was cooked in a microwave oven 15 min
before the load inspection and stored in a warm storage. Asa seasoning, 3 g of seasoned salt (Gomashio [salted sesami];
Marumiya Food Industry, Tokyo, Japan) was added to therice and 150 mL of water was provided to the subjects. The
composition of the loaded diet is shown in Table 1, 2. The
subjects were instructed to chew the rice about 30 times per
bite. The intake time was 10 min.

Fat
Carbohydrate
Salt equivalent

15 kcal0.42 g1.2 g

0. 5 g0.71 gExercise procedure

GB10 group1) Abdominal exercises: Rolled up in 3 seconds and returnedin 3 seconds (2 min).
2) Waist twist: twisted in 3 seconds and returned in 3 seconds.
Left and right ( 2 min).
3) Rowing: Pulled for 3 seconds and returned in 3 seconds (2min).
4) Punching: Pressed in 3 seconds and returned in 3 seconds(2 min).
5) Leg press: Pressed in 3 seconds and returned in 3 seconds
left and right (2 min).
GS10 group1) Shoulder reflection: Raised in 3 seconds and lowered in 3
seconds (2 min).
2) Side vent: The body was bent sideways in 3 seconds andreturned in 3 seconds (2 min).
3) Abduction: opened in 3 seconds and returned in 3 seconds.
Left and right (2 min).
4) Knee extension: raised, held for 3 seconds and lowered.
Left and right (2 min).
5) Marching: Raised, held for 3 seconds and lowered. Leftand right (2 min).
GS6 group1) Side vent: The body was bent sideways in 3 seconds andreturned in 3 seconds (2 min).
2) Hip Abduction: Opened in 3 seconds and returned in 3
seconds. Left and right (2 min).
3) Marching: Raised and held for 3 seconds. Left and right (2min).

_ 2 61 _Effects of Sub-Aleurone-Remaining Rinse-Free Rice

Statistical Analysis
The statistical analysis was performed with a paired
t-test using statistical analysis software SAS (SAS 9.4; SAS
Institute Japan, Minato-ku, Tokyo) and SPSS (Statistics 25;
IBM Japan, Chuo-ku, Tokyo). Calculated data are presented
as mean ± standard error mean in the figures and mean ±standard deviation in the text and Tables. The measured values
were analyzed by two-tailed paired t- test/Dunnett multiple
comparison tests 9, 10). Regarding the safety evaluation, timecourse comparison and group comparison were performed by
the paired t-test. A risk rate of less than 5% was considereda significant difference.

Ethical standards
This study was conducted in compliance with the
Declaration of Helsinki (revised at the 2013 WMA Fortaleza
General Assembly) and the ethical guidelines for humanbased medical research (notification by Ministry of

Education, Culture, Sports, Science and Technology [MEXT]
and Ministry of Health, Labour and Welfare [MHLW]). This
research obtained the approval of the Ethical Committee of
the Society for Glycative Stress Research (GSE 2018-001),
which has discussed the ethics and validity of the study.
The clinical trial for this study was pre-registered (UMIN#000039165).

Results

Changes in blood glucose
The blood glucose level of GS10 was significantly lower
than that of the control 30 min after eating (p < 0.05, Fig.
3). GS6 showed significantly lower values than those of thecontrol at 30 min (p < 0.01) and at 90 min (p < 0.05). There
were no significant differences in glucose AUC, iAUC,
Cmax, and Tmax (Table 3).

230

Control
GB10
GS10
GS6

210

Blood Glucose (mg/dL)

190
170
150
130
110
90
70
50

0

30

60

90

120

Time (min)Fig. 3. Results are expressed as mean ± SD, n = 12, * p < 0.05, ** p < 0.01 vs control by twotailed paired t-test/Dunnett multiple comparison tests.SD, standard deviation.

Table 3. AUC, iAUC, Cmax and Tmax of glucose.

Control
GB10
GS10
GS6

AUC
(mg・min/dL)

iAUC(mg・min/dL)

Cmax(mg/dL)

Tmax
(min)

1,7161 ± 4,098

4,801 ± 3,267

170.4 ± 41.0

50.0 ± 26.6

4,888 ± 2,942

173.4 ± 42.5

55.0 ± 21.5

1,6705 ± 3,834

1,6958 ± 4,003
1,595 ± 4,082†

4,495 ± 2,851

3,983 ± 3,26 0

170.4 ± 4 0.0
163. 3 ± 42.7

52.5 ± 18.6
52.5 ± 18.6

Results are expressed as mean ± SD, n = 12, † p = 0.0598 vs control by two-tailed paired t-test/Dunnett multiple
comparison tests. AUC, area under the curve; iAUC, incremental area under the curve; Cmax, maximam value of glucose
concentration; Tmax, time to maximum value of glucose concentration; SD, standard deviation.

_ 2 62 _Glycative Stress Research

Changes in insulin

with obesity were much fewer 11, 12). Since insulin secretion
decreases with age 13). T2DM is more likely to develop simply
by mild increase in insulin resistance due to overeating andlack of exercise 14, 15).
The reason for this is that the Japanese have a significantly
lower insulin secretory capacity in the early stage after glucose
loading, as compared with other ethnic groups. Furthermore,when the ATP-binding cassette transporter 1 (ABC1) ofpancreatic β-cells is impaired, it becomes difficult to preventthe accumulation of excess cholesterol in the β-cell membrane,
resulting in impaired insulin secretion 16). It has been reported
that some gene polymorphisms tend to cause insulin secretion
disorders constitutionally.
Based on the glucose tolerance data in the Ningen Dock/
Medical Checkups (data from the Nippon Kokan Hospital)and previous reports 11-16), the “process from normal to glucose
intolerance resulting in T2DM ” is outlined. Most subjects
shift from normal weight to mild obesity/visceral obesity,
during which the FBG level gradually approaches the upper
limit of the standard range (Ningen Dock Society standard
value of 99 mg/dL). Concurrently, fasting insulin gradually
increased in those who initially had less than 5 μU/mL,

Insulin levels of the GB10 (p < 0.05), GS10 (p < 0.01),
and GS6 (p < 0.005) were significantly higher than those of
the control group 60 min after eating (Fig. 4 ). Insulin AUC,
iAUC, and Cmax were significantly higher in GS10 and GS6
than in the control group (p < 0.05, Table 4 ). There were no
significant differences in HOMA-IR between groups.

SafetyFisher exact test was used for statistical analysis of thenumber of cases of side effects and adverse events. No side
effects attributable to the test product were confirmed in all
subjects.

Discussion

Glucose tolerance
Among Japanese with impaired glucose tolerance,
those with low insulin secretion are common, while those

80

Control
GB10
GS10
GS6

70

Insulin (μU/mL)

60
50
40
30
20
10
0
0

30

60

90

120

Time (min)Fig. 4. Results are expressed as mean ± SD, n = 12, * p < 0.05, ** p < 0.01 vs control by twotailed paired t-test/Dunnett multiple comparison tests.SD, standard deviation.

Table 4. AUC, iAUC, Cmax and Tmax of insulin and HOMA-IR.
AUC(μU・min/mL)
Control
GB10
GS10
GS6

3,395 ± 1,052

iAUC(μU・min/mL)

Cmax(μU/mL)

Tmax
(min)

HOMA-IR

2,530 ± 1,061

4 0.5 ± 13.1

70.0 ± 34.6

1.84 ± 2.01

3,328 ± 1,023 **50.3 ± 18.0 **65.0 ± 25.0

1.31 ± 0.82

3,638 ± 1,169

2,993 ± 1,015 *4,318 ± 1,856 *

3,626 ± 1,592*

3,954 ± 1,217 *

47.1 ± 17.0 †55.2 ± 19.8*

70.0 ± 14.8

60.0 ± 25.6

1.37 ± 0.75

1.46 ± 0.98

Results are expressed as mean ± SD, n = 12, † p = 0.069, * p < 0.05, ** p < 0.01 vs control by two-tailed paired t-test/Dunnett multiple
comparison tests. AUC, area under the curve; iAUC, incremental area under the curve; Cmax, maximam value of insulin concentration; Tmax,
time to maximum value of insulin concentration; HOMA-IR, homeostasis model assessment of insulin resistance; SD, standard deviation.

_ 2 63 _Effects of Sub-Aleurone-Remaining Rinse-Free Riceand HOMA-IR increased. This condition is dominant ininsulin resistance. Therefore, postprandial hyperglycemia
also gradually rises, and blood glucose spikes are frequently
induced. Unless lifestyle factors are improved, this condition
continues for several years, and the amount of insulin
secretion gradually decreases. This is an intermediate statewith impaired insulin secretion. As the bad lifestyle habits
continue, insulin secretion decreases, FBG rises significantly
above the standard range, and postprandial hyperglycemia
exceeds 200 mg/dL. This is a state in which impaired insulin
secretion is predominant and is a pre-stage for the onset of
diabetes.
In this study, 12 middle-aged men and women without
exercise habits (55.3 ± 5.2 years old) were analyzed, andthree types of mild muscle exercise were performed as acontrol when postprandial blood glucose was observed
without exercise. A non-crossover type repeated test was
conducted for postprandial blood glucose transition, and acomparative analysis was performed. The glucose toleranceof the subjects showed slightly higher scores in FBG (103.0± 13.0 mg/dL) and fasting insulin (7.21 ± 8.12 μU/mL), andslightly higher in HOMA-IR (1.84 ± 2.01). Although fasting
insulin levels do not show a decrease in insulin secretion,
postprandial insulin secretion is low due to a lower insulin
AUC. This finding suggests that postprandial insulin
secretion may be potentially affected early on before fasting
insulin levels decline.

Improved glucose tolerance
In this study, a non-crossing type repeated test was
conducted on the postprandial blood glucose transition whenthree types of mild muscle exercise were performed just after
the meal, and the data were compared with a control without
exercise. The same participants took the test weekly in thefollowing order.
Order GroupTime
Calorie consumption*
· 1 stControl
0 min
0 kcal· 2nd GB10
10 min35 kcal· 3rd GS10
10 min35 kcal· 4th GS6
6 min
21 kcal* Estimated calorie consumptions are calculated for astandard weight of 60 kg.
As a result, both exercises showed a decrease in blood
glucose AUC and an increase in insulin AUC, alleviation of
postprandial blood glucose elevation and improvement of
insulin secretory ability. However, the results of comparing
the three types of muscle exercises were different than
expected. The effect of improving glucose tolerance washighest in GS6 (4th), which consumes the least calories.
The order of FBG, glucose Cmax and insulin AUC were
GS6 (4th), GS10 (3rd), GB10 (2nd), and control (1st). In these
items, glucose tolerance was most improved in the GS6 (4thgroup) which had an accumulation of exercise. The exercise
time and the thickness of the rubber band did not affect theeffect of improvement of glucose tolerance. It is consideredthat even if the exercise amount is small, a cumulative effectwill appear by continuing performance once a week.
What is interesting is that the secretory effect of thispostprandial insulin is different from dietary intervention.

In the case of dietary intervention, the effect of suppressing
blood sugar elevation by delaying glucose absorption is theprimary effect 17-19). It may, in part, be related to the effectof stimulating GIP (glucose-dependent insulinotropic
polypeptide) secretion from the small intestine, but in thecase of dietary intervention, insulin secretion remains lower
than the control group. Conversely in the case of this exercise
intervention, postprandial blood hyperglycemia is alleviatedas a result of the increase in insulin secreted in response to
the glucose elevation stimulation.
The present subjects are those with impaired insulin
secretion compared with healthy young people, i.e., middleaged, having little or no exercise habit, overweight, or close
to the metabolic syndrome boundary area. Since subjects
had these characteristics, physical exercise might have
improved their insulin secretion and alleviated postprandial
hyperglycemia. The effect was further enhanced by theaccumulation of exercise therapy once a week.

Benefits of exercise
It has been mainly considered that physical activity
increases glucose consumption and glucose uptake to skeletal
muscle may ameliorate hyperglycemia.
Regarding the relationship between exercise and insulin
secretion, it has been reported that female students without
exercise habits tend to increase insulin secretion due to exercise.
Ingesting protein and lipids promotes GIP secretion 20), however,it seems that young people do not always increase insulin
secretion 21-23).
There are few surveys targeting middle-aged and elderly
people. Dietary treatment (1,500 ± 100 kcal, P : F : C = 7 : 27
: 56) and exercise therapy (aerobic exercise + muscle training
with moderate intensity) have been conducted with 9 middleaged patients with T2DM for 2- 4 weeks, resulting that oGTT
(oral glucose tolerance test) decreased AUC, while there wasno significant change in HOMA-IR 24). Changes in insulin
secretion after glucose load have not been investigated in thisstudy. The results that post-prandial insulin secretion wasincreased by muscular exercise in middle-aged people withlatent insulin secretion as in this study are valuable.

Acute and chronic effects of exercise
An increase in glucose consumption due to exercise
leads to suppression of postprandial hyperglycemia. Thisis an acute effect obtained by one-time exercise. Although
it depends on the amount of exercise, a subject whose
insulin secretion is normal often does not change or shows adecrease in insulin secretion due to exercise.
Regarding chronic effects, regular exercise causes
weight loss and visceral fat reduction in obese persons andimproves blood adipocytokine balance 25). Continuation of
exercise habits also induces a decrease in leptin concentration(especially in those with increased leptin resistance), decrease
in resistin (especially in T2DM patients and those with highinflammatory cytokines), and an increase in adiponectin(especially in those with decreased visceral fat mass by
exercise). These changes improve insulin resistance. However,
adipose tissue loss cannot be expected with exercise similar
to this study, and it is unlikely that this mechanism of action_ 264 _Glycative Stress Researchis involved.
Exercise-induced increase in GLUT4 (glucose transporter
type 4) improves glucose metabolism in skeletal muscle. As
the mechanism, it is reported that the elevation of GLUT4
expression 26-29), the promotion of GLUT4 translocation 30, 31)
and the increase of mitochondrial number are important. The
improvement of insulin resistance can be explained by
GLUT4 increase, however, it cannot explain the increase of
insulin secretion by exercise.
As another factor, favorable effects of exercise via
lipid metabolism are also expected. Its insufficiency
causes accumulation of triglycerides and FACoA (fattyacyl-coenzyme A) in skeletal muscle, inhibition of IRS1 (insulin receptor substrate 1) tyrosine phosphorylation,and decreased PI3K (phosphoinositide 3-kinase) activity,
resulting in impaired GLUT4 translocation 32). In contrast,
if adiponectin secretion from visceral fat is increased byexercise and TNF-α (tumor necrosis factor- α)/resistin isdecreased, AMP kinase can be activated to increase fatburning (β-oxidation of fatty acid), that may improve insulin
resistance and glucose tolerance 33).
When glucose tolerance decreases and glucose
metabolism function declines, postprandial hyperglycemia
is more likely to occur, leading to the condition with highglycative stress and high amounts of advanced glycation end
products (AGEs). As a result, insulin secretion is reduced 34-36).
Experimentally, when AGEs are topically applied to pancreatic
β cells, insulin mRNA decreases and the protein levels of
intracellular proinsulin and insulin decrease 37). Furthermore,in the process; preproinsulin → preinsulin → insulin inside
pancreatic β-cells, carbonylation of lysine (Lys) and arginine(Arg) residues and succinylation of cysteine residue (-S)
occur, which disturbs insulin production. 38). Approximately
9 % of blood insulin in T2DM patients undergoes AGE
modification (glycated insulin production) and loses insulinfunction, resulting in increased insulin resistance 39). It is
expected that exercise improves insulin secretion by reducing
glycative stress.

Research limitation
In this study, the changes in postprandial blood
glucose immediately after the three kinds of exercise loads
are compared with a control in a non-crossing type test.
Compared with the crossover test, it cannot eliminate thefactors of the cumulative effect and the elements of orderfrom the analysis. Therefore, it was not able to compare theeffects on glucose tolerance and insulin secretion among thethree groups. On the other hand, the advantage is that the
cumulative effect of the exercise could be observed.

Conclusions
This study showed that middle-aged people who tend tolack exercise but do muscle exercise using a super-soft rubberband for about 6 to 10 min after eating are able to reduce
postprandial hyperglycemia, and its mechanism is based onincreased insulin secretion. The results suggest that once aweek, the persons with a lack of physical activity may continue
their physical activity to restore the decreased insulin secretion.
Insufficient exercise promotes skeletal muscle mass reduction
with aging, and causes glycative stress through decreased
glucose consumption and increased insulin resistance, therefore
causing a vicious cycle in which insulin secretion frompancreatic β cells is further reduced 7). It is quite possible that
this cycle can be inhibited by continuing “muscle load training”
as presented in this study.

Conflict of Interest Statement
The present study was partly supported by Kyowa Rubber
Co.Ltd.

Safety: adverse effects by exercise
When exercise intensity and load are excessive, glucagonand catecholamine secretion are increased, which acts on
insulin antagonism. In more intense exercise, blood ketone
body production, ROS (reactive oxygen species) production,and thiobarbituric acid reactive substances (TBARS) increase
remarkably, and degenerative changes with organ damage
and aging deteriorate 40-43). In addition, the secretion of
insulin antagonist hormones (counterregulatory hormone),i.e., catecholamine, glucagon, growth hormone, and cortisol
occurs during exercise. This reaction induces adaptationby continuing exercise, and the increase rate of insulin
antagonistic hormone becomes moderated 44). Therefore, fordiabetic exercise therapy, moderate or lower intensity anda duration of 10 to 30 min are desirable 43). There were no
adverse events during this study. It is considered that theexercise therapy performed is effective for avoiding adverse
events.

_ 2 65 _Effects of Sub-Aleurone-Remaining Rinse-Free Rice

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