Acute changes in glucose induced by continuous or intermittent exercise in children and adolescents with type 1 diabetes

ABSTRACT Objective: To estimate the rate of change during exercise and during recovery in moderate-continuous exercise (MCE) and high-intensity intermittent exercise (HIIE) in children and adolescents with type 1 diabetes (T1D). Subjects and methods: Participants performed 2 sessions of exercise: thirty minutes of continuous activity on a cycle ergometer (60% of VO2max) and thirty minutes (60% VO2max) interspersed with five bouts of maximum intensity lasting ten seconds every five minutes. Capillary blood glucose was measured before and after each test. The glucose rate of change in exercise (RoCE) was calculated (final blood glucose - onset blood glucose/exercise time), and the glucose rate of change in recovery (RoCR) (blood glucose 30 minutes after exercise - end of exercise blood glucose/recovery time). Results: The study included thirty-one participants (aged 13 ± 1.88 years). A lower blood glucose reduction was observed in the HIIE group, as well as better recovery values before, after, and thirty minutes after the test, respectively (333.14 ± 69.53, 226.19 ± 68.05 and 201.77 ± 66.84 versus 211.36 ± 91.03, 155.98 ± 82,68 and 165.76 ± 72.94). Covariance analyses showed a significant difference in glycemic variation between continuous and intermittent protocols immediately after exercise (−2.90 versus −2.08) and during the recovery period (−0.677 versus −0.389). Conclusions: HIIE led to a lower glucose reduction rate per minute during exercise and better recovery in the first 30 minutes after exercise compared to MCE in children and adolescents with T1D.

Effects of different exercise on liver lipid accumulation and FGF21 secretion in obese rats / 中国应用生理学杂志

Objective: To investigate the effects of continuous exercise training (CT) and high-intensity interval exercise training (HIIT) on liver lipid metabolism and the correlation of the level of fibroblast growth factor 21(FGF21) in serum and liver tissues. Methods: Male SD rats were randomly divided into normal diet group (N) and obesity model group (H) after 1 week of adaptive feeding. Rats in the obesity model group were fed with 45% high-fat diet for about 8 weeks, and 20% weight increase compared with normal rats was considered as obesity. The rats were divided into normal diet control group (LC), normal diet HIIT group (LHI), normal diet CT group (LCT), High fat diet-induced obese control group (OC), obese HIIT group (OHI), and obese CT group (OCT) (n=10). Exercised rats were given weight-bearing swimming training intervention for 8 weeks. Blood samples were collected at least 24h after the last exercise intervention to detect the serum levels of inflammatory factors and FGF21. Liver tissue samples were collected to detect the lipid content, lipid metabolic enzyme content and FGF21 expression level. Results: Compared with LC group, the body weight, serum inflammatory factors levels and hepatic triglyceride content were increased significantly (P＜0.05). Hepatic triglyceride content was downregulated in LHI group and FGF21 expression level was enhanced in LCT group (P＜0.05). Compared with OC group, the body weight and hepatic triglyceride content were decreased significantly (P＜0.05), mitochondrial CPT-1β and β-HAD enzyme contents in liver were increased significantly (P＜0.05) in OHI group, the contents of LPL and FAT/CD36 enzyme in liver and the levels of FGF21 in serum and liver of OCT group were increased significantly (P＜0.05). Conclusion: Both exercise modes can reduce the body weight in normal and obese rats, and lipid deposition in the liver of obese rats. HIIT has a more significant effect on alleviating liver lipid deposition in obese rats by upregulating mitochondrial lipid oxidation level in normal and obese rats. CT improves the levels of FGF21 in serum and liver tissues of normal and obese rats, enhances enzyme contents that involved in fatty acids uptake to the liver, which has limited effect on alleviating lipid deposition in liver of obese rats.

Effect of Exercise Type on Vascular Stabilization Factor in Ischemic Stroke Patients.

Stroke is one of the leading causes of mortality and disability in the world. The angiogenesis strategy is a new therapeutic approach to exercise in these patients. The purpose of this study was to investigate the effect of continuous exercise on serum levels of vascular stabilizing factor and its consequences. MethodsIn this randomized clinical trial study, 30 patients with stroke who volunteered to participate in the study, aged 45 - 65 years, were selected by convenience sampling and non-random sampling method. Subjects were randomly selected. The patients were randomly divided into intervention group (4 weeks of continuous exercise in 40 - 60 minutes pedal with 60 - 65% VO2 peak intensity for 5 days per week and physiotherapy) and control group (physiotherapy only). Blood angiogenesis and motor function levels were measured at baseline and twenty-eight days after the last exercise session. Data was analyzed by using Stata software version 13 at the significance level of 0.05. ResultsIn this trial, thirty patients completed the study period, and were included in the analysis. The mean ages of patients in the control and intervention groups were 55.66 (S.D.: 6.69) and 61.46 (S.D.: 6.47) years, respectively. Serum levels of angiopoietin-1 increased after exercise at alpha level (P = 0.011). The reduction of the Modified Rankin Scale was obtained as a secondary consequence (P = 0.001). ConclusionsContinuous exercise training over four weeks can improve the prognosis of patients by altering the levels of angiogenesis-stabilizing factor in decreasing the symptoms of stroke.

Influence of repetition exercise requiring less work than continuous exercise on the vascular endothelial function / 体力科学

High-intensity interval exercise leads to greater improvements in the vascular endothelial function than continuous exercise at moderate intensity. However, few studies have been performed on the effects of repetition exercise consisting of high-intensity exercise followed by complete rest on the arterial function. Therefore, the purpose of this study was to investigate the effects of repetition exercise on the vascular endothelial function determined by flow-mediated vasodilation (FMD). Eleven healthy male subjects completed two exercise sessions on a cycle ergometer in a counterbalanced order. The exercise sessions were 20 min cycling at 50% maximal work rate (Wmax) (continuous exercise, CE) and 20 × 20-sec intervals at 100%Wmax interspersed with 40-sec intervals at complete rest (repetition exercise, RE). Before and after each protocol, the brachial systolic and diastolic blood pressure were measured in the supine position. Relative FMD was assessed at rest and 30 and 60 min after each exercise regimen, and then the normalized FMD (nFMD) was calculated from the peak shear rate. The FMD significantly increased 30 min after RE (8.2 ± 1.5% to 11.5 ± 3.1%, p<0.01) and non-significantly increased 30 min after CE (7.5 ± 1.6% to 8.1 ± 2.1%, n.s.) before returning to baseline at 60 min after both exercise regimens. The FMD value at 30 min after RE was significantly greater than that at 30 min after CE (p<0.01). The nFMD (a.u.) significantly increased 30 min after RE (1.38 ± 0.64 to 2.00 ± 0.94, p<0.05) and non-significantly increased 30 min after CE (1.20 ± 0.54 to 1.49 ± 0.57, n.s.) before returning to baseline at 60 min after both exercise regimens. These results suggest that repetition exercise may lead to an acute improvement in the vascular endothelial function.

INFLUENCE OF COOLING ON CONTINUANCE CONTINUOUS CONTRACTION TIME PRIOR TO MODERATE ISOMETRIC EXERCISE / 体力科学

Purpose : To investigate the cooling effect on muscles prior to continuous isometric muscle contraction. Furthermore, tissue compliance, pressure pain threshold, deep tissue temperature, and tissue circulation volume were measured to investigate the cooling effect on a physical reaction. Method : The biceps brachii muscle was contracted isometrically and continuously at the 90(-) degree in flexion position with 40% of maximum contraction. The task was ceased when subjects could not keep over 70 degrees of elbow flexion. An injection type cooling stimulator was used on the biceps brachii muscle as a cooling modality. Results : The continuous contraction time in the cooled group increased significantly compared with the control group. In addition, tissue compliance and pressure pain threshold showed significant differences between the two groups. Conclusion : This study suggested that the isometric continuous contraction time in cooled muscles can be extended to 40% of MVC. The inhibition of muscle metabolism, an increase in the pressure pain threshold, and tissue compliance may affect muscle endurance.

Biomarcadores de estresse em ratos exercitados por natação em intensidades igual e superior à máxima fase estável de lactato / Biomarkers of stress in rats exercised in swimming at intensities equal and superior to the maximal estable lactate phase

INTRODUÇÃO: O estresse alcançado durante exercício agudo/crônico é relevante, pois altos índices de estresse podem prejudicar o bem-estar dos animais. As concentrações dos hormônios adrenocorticotrófico (ACTH) e corticosterona, bem como as concentrações de ácido ascórbico e colesterol das glândulas adrenais são importantes biomarcadores de estresse. OBJETIVO: Analisar a sensibilidade de diferentes biomarcadores de estresse em ratos durante exercício agudo de natação em diferentes intensidades. MÉTODO: Ratos (18) adaptados à natação foram submetidos a três testes de 25 minutos suportando cargas 5,0; 5,5 e 6,0 por cento do peso corporal (PC), para obtenção da máxima fase estável de lactato (MFEL). Em seguida, os animais foram divididos em dois grupos: M (n = 9), sacrificado após 25 minutos de exercício na intensidade de MFEL e S (n = 9), sacrificado após exercício exaustivo, em intensidade 25 por cento superior a MFEL. Para comparações, um grupo controle C (n = 10) foi sacrificado em repouso. RESULTADOS: As concentrações séricas de ACTH e corticosterona foram superiores após exercício em ambas as intensidades comparadas com o grupo controle (P < 0,05). As concentrações de ACTH e corticosterona do grupo S foram, ainda, maiores do que as do grupo M (P < 0,05). As concentrações de colesterol e ácido ascórbico na adrenal dos grupos exercitados (M e S) foram inferiores às do grupo controle (P < 0,05). Não houve diferença das concentrações de ácido ascórbico e colesterol da adrenal quando comparadas as duas intensidades de exercício (M e S) (P < 0,05). CONCLUSÃO: Todos os biomarcadores do eixo HHA apontaram alterações no nível de estresse de ratos submetidos a exercício agudo de natação; as concentrações séricas de ACTH e corticosterona mostraram-se mais sensíveis a pequenas alterações na intensidade do exercício.

INTRODUCTION: The level of stress during acute/chronic exercise is important, since higher levels of stress may impair animal welfare. The adrenocorticotrophic (ACTH) and corticosterone hormone concentrations, as well as cholesterol and ascorbic acid concentrations in adrenal gland, are considered an important stress biomarker. PURPOSE: To analyze the sensitivity of the different biomarkers during acute swimming exercise in different intensities performed by rats. METHODS: Male Wistar adult rats (n = 18) previously adapted to swimming were submitted to three 25 min. swimming tests with loads of 5.0; 5.5 and 6.0 percent of their body weight (BW), for maximum lactate steady state (MLSS) determination. After MLSS attainment, the animals were divided into two groups: M (n = 9) sacrificed shortly after a 25 min. session of exercise at the MLSS intensity or S (n = 9) sacrificed after exhaustive exercise at intensity 25 percent above MLSS. For comparison purposes, a control group C (n = 10) was sacrificed in rest. RESULTS: Serum ACTH and corticosterone concentrations were higher after exercise for the two groups (M and S) when compared with control group C (P < 0.05). The group S presented higher concentrations for both hormones in relation to the group M (P < 0.05). The concentrations of the cholesterol and ascorbic acid in adrenal were lower after exercise for the two groups (M and S) when compared with control group C (P < 0.05). No significant differences in adrenal ascorbic acid and cholesterol levels were observed when the two exercise intensities (M and S) were compared (P < 0.05). CONCLUSION: All biomarkers of HPA activity pointed alterations in the stress level of the rats submitted to acute swimming exercise. ACTH and corticosterone serum concentrations showed to be more sensitive to small alterations in the effort intensity.

THE COMPARISON OF POST EXERCISE OXYGEN CONSUMPTION BETWEEN TWO DIFFERENCE SUPRAMAXIMAL EXERCISES / 体力科学

Exercise intensity has been identified as a major determinant of the excess post-exercise oxygen consumption (EPOC). However, no studies have compared the prolonged EPOC after supramaximal intermittent exercise and supramaximal continuous exercise. Six young healthy male [age=26±3 (mean±SD) yr ; stature=175.4±5.7 cm ; body weight=66.8±6.7 kg ; maximal oxygen uptake (VO₂max)=44.1±8.5 ml/kg/min] xercised on separate days on a cycle ergometer at two equated total energy expenditures (intermittent exercise : 7×30-second intervals at 150%VO₂max with intervening 15-seconds rest periods ; continuous exercise : 5 min at 105%VO₂max) and then sat quietly in an armchair for 3h. A control trial without any exercise was also performed in a counterbalanced research design. The VO₂, carbon dioxide output (VCO₂), pulmonary ventilation (VE), respiratory exchange ratio (RER), heart rate (HR) and blood lactate concentration (LA) were measured before exercise, during exercise and during the 3-h recovery period. The mean VO₂ after intermittent trial at 150%VO₂max were higher than these of the control trial and the continuous trials at 105%VO₂max for 3-h recovery periods (p<0.05). The 3-h EPOC value for intermittent exercise trial (10.5±2.4L) was significantly greater than that of continuous exercise trial (4.8±2.7L) (p<0.05). The mean RER values for intermittent exercise trial were significantly lower than those of the control trial during 60-180 min post-exercise (p<0.05). We examined the effect of supramaximal exercise intensity on the magnitude of 3-h EPOC after 12-fasting. In the present study, 3-h EPOC was significantly greater for supramaximal intermittent exercise compared with the supramaximal continuous exercise when the amounts of work output performed are same. Therefore, our results indicate that exercise intensity may be a primary factor of 3-h EPOC even in a supramaximal exercise and that one of mechanisms for the 3-h EPOC would be related to the promoted lipid metabolism.