Exercise and glycemic control in individuals with type 2 diabetes

Title from PDF of title page (University of Missouri--Columbia, viewed on June 7, 2012).The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file.Thesis advisor: Dr. ThyfaultVita.Includes bibliographical references.M.S. University of Missouri--Columbia 2011."December 2011"Type 2 diabetes (T2D) and the associated impaired glycemic control greatly increases the risk of cardiovascular disease mortality. PURPOSE: It is unknown if or for how long a single bout of exercise will reduce post-prandial glucose levels in individuals with T2D. METHODS: We recruited 9 individuals with T2D who were not using exogenous insulin and were sedentary. The subjects consumed a eucaloric diet containing identical food components at each meal during two separate 3 day trials while wearing CGMS monitors to continually monitor blood glucose levels. During one 3 day trial the subjects performed one 60 minute, supervised exercise bout (60% of heart rate reserve) prior to breakfast on the morning of the first day. During the second 3 day trial, the subjects maintained their sedentary lifestyle (sedentary). RESULTS: A comparison of the 2 trials revealed that one bout of exercise did significantly reduce the glucose AUC for the 2nd meal post exercise. There was also a decrease in 24 hour average blood glucose level for the first day after the exercise bout (p=0.003). CONCLUSION: These results suggest that one moderate-intensity bout of aerobic exercise is effective in significantly improving glycemic control in subjects with T2D, however the improvement only seemed to last for a single day

Physical inactivity rapidly alters glycemic control in young, lean, previously active volunteers [abstract]

Postprandial hyperglycemia is a better predictor of cardiovascular disease and all cause mortality than fasting blood glucose or hemoglobin A1c. Physical inactivity is associated with insulin resistance and cardiovascular disease. To determine whether transitioning from a high to low level of physical activity affects glycemic control, we equipped young (30 [plus or minus] 1 y), lean (24 [plus or minus] 1 kg-m-2), healthy, physically active (>10,000 steps-d-1) volunteers (N=10) with continuous blood glucose monitors for 3 days during separate ACTIVE (habitual physical activity) and INACTIVE ([less than or equal to]5,000 steps-d-1) phases (diet replicated across phases)

Neither recurrent hypoglycemia nor chronic aerobic training alter the content of MCTs in the ventromedial hypothalamus

Many individuals with diabetes use medications or exercise to control blood glucose concentrations, which can lead to episodes of hypoglycemia. Although chronic hyperglycemia leads to many diabetic complications, hypoglycemia is an acute threat to the health of individuals, and can lead to myocardial ischemia and arrhythmias, as well as increasing inflammation, oxidative stress, and thrombotic and fibrinolytic processes. Either antecedent exercise or antecedent hypoglycemia lead to a blunted counter-regulatory response to a subsequent hypoglycemia episode. Acute exercise has been shown to increase monocarboxylate transport proteins (MCTs) in the ventromedial hypothalamus (VMH) of the brain, which is involved in regulating the counter-regulatory response to restore euglycemia. The MCTs shuttle lactate in and out of cells, however when is lactate infused into the VMH has been shown to interfere with the counter-regulatory response. Additionally, antecedent recurrent hypoglycemia has been shown to increase lactate transport in the brain. Therefore, the current studies investigated what effect exercise training or recurrent antecedent hypoglycemia had on MCT proteins in the VMH. Adult male Sprague-Dawley rats were used for both studies, randomized to receive either 6-7 weeks of aerobic training, sedentary behavior, 3 days of insulin induced hypoglycemia, or 3 days of saline injection. The increases in cytochrome c oxidase activity among the aerobically trained group showed that training adaptations occurred, however, there were no significant differences in MCT proteins within the VMH between the trained versus sedentary rats. While each of the 3 days of hypoglycemia or saline injection showed differences in 30 minute post-injection glucose concentrations, no significant differences in MCTs were observed in the VMH between the 2 groups on day 4

The Relationship Between Physical Activity and Perceived Health Status in Older Women: Findings from the Woman’s College Alumni Study

Using data collected from the Woman’s College (WC) Alumni Study, the purpose of this study was to determine whether perceived health status is related to physical activity in older women. A multiple linear regression analysis was conducted to examine the relationship between amounts of physical activity and self-reported health status. The results of the current study reveal that the level of physical activity is significantly correlated with perceived health status. The findings of this study have implications for the assessment of older individuals’ health and may lead to interventions that are tailored to increase physical activity among older women

Myoelectric activity during electromagnetic resistance alone and in combination with variable resistance or eccentric overload.

The purpose of this study was to compare the effects of electromagnetic resistance alone, as well as in combination with variable resistance or accentuated eccentric methods, with traditional dynamic constant external resistance exercise on myoelectric activity during elbow flexion. The study employed a within-participant randomized, cross-over design whereby 16 young, resistance-trained male and female volunteers performed elbow flexion exercise under each of the following conditions: using a dumbbell (DB); using a commercial electromagnetic resistance device (ELECTRO); variable resistance (VR) using a setting on the device that attempts to match the level of resistance to the human strength curve, and; eccentric overload (EO) using a setting on the device that increases the load by 50% on the eccentric portion of each repetition. Surface electromyography (sEMG) was obtained for the biceps brachii, brachioradialis and anterior deltoid on each of the conditions. Participants performed the conditions at their predetermined 10 repetition maximum. The order of performance for the conditions was counterbalanced, with trials separated by a 10-minute recovery period. The sEMG was synced to a motion capture system to assess sEMG amplitude at elbow joint angles of 30°, 50°, 70°, 90°, 110°, with amplitude normalized to maximal voluntary isometric contraction. The anterior deltoid showed the largest differences in amplitude between conditions, where median estimates indicated greater concentric sEMG amplitude (~7 to 10%) with EO, ELECTRO and VR compared with DB. Concentric biceps brachii sEMG amplitude was similar between conditions. In contrast, results indicated a greater eccentric amplitude with DB compared to ELECTRO and VR, but unlikely to exceed a 5% difference. Data indicated a greater concentric and eccentric brachioradialis sEMG amplitude with DB compared to all other conditions, but differences were unlikely to exceed 5%. The electromagnetic device tended to produce greater amplitudes in the anterior deltoid, while DB tended to produce greater amplitudes in the brachioradialis; amplitude for the biceps brachii was relatively similar between conditions. Overall, any observed differences were relatively modest, equating to magnitudes of ~5% and not likely greater than 10%. These differences would seem to be of minimal practical significance

Gaining more from doing less? The effects of a one-week deload period during supervised resistance training on muscular adaptations.

Based on emerging evidence that brief periods of cessation from resistance training (RT) may re-sensitize muscle to anabolic stimuli, we aimed to investigate how a 1-week deload interval at the midpoint of a 9-week RT program affected muscular adaptations in resistance-trained individuals. Thirty-nine young men (n=29) and women (n=10) were randomly assigned to one of two experimental, parallel groups: An experimental group that abstained from RT for 1 week at the midpoint of a 9-week, high-volume RT program (DELOAD) or a traditional training group that performed the same RT program continuously over the study period (TRAD). The lower body routines were directly supervised by the research staff while upper body training was carried out in an unsupervised fashion. Muscle growth outcomes included assessments of muscle thickness along proximal, mid and distal regions of the middle and lateral quadriceps femoris as well as the mid-region of the triceps surae. Adaptations in lower body isometric and dynamic strength, local muscular endurance of the quadriceps, and lower body muscle power were also assessed. Results indicated no appreciable differences in increases of lower body muscle size, local endurance, and power between groups. Alternatively, TRAD showed greater improvements in both isometric and dynamic lower body strength compared to DELOAD. Additionally, TRAD showed some slight psychological benefits as assessed by the readiness to train questionnaire over DELOAD. In conclusion, our findings suggest that a 1-week deload period at the midpoint of a 9-week RT program appears to negatively influence measures of lower body muscle strength but has no effect on lower body hypertrophy, power or local muscular endurance

Neither recurrent hypoglycemia nor chronic aerobic training alter the content of MCTs in the ventromedial hypothalamus

Many individuals with diabetes use medications or exercise to control blood glucose concentrations, which can lead to episodes of hypoglycemia. Although chronic hyperglycemia leads to many diabetic complications, hypoglycemia is an acute threat to the health of individuals, and can lead to myocardial ischemia and arrhythmias, as well as increasing inflammation, oxidative stress, and thrombotic and fibrinolytic processes. Either antecedent exercise or antecedent hypoglycemia lead to a blunted counter-regulatory response to a subsequent hypoglycemia episode. Acute exercise has been shown to increase monocarboxylate transport proteins (MCTs) in the ventromedial hypothalamus (VMH) of the brain, which is involved in regulating the counter-regulatory response to restore euglycemia. The MCTs shuttle lactate in and out of cells, however when is lactate infused into the VMH has been shown to interfere with the counter-regulatory response. Additionally, antecedent recurrent hypoglycemia has been shown to increase lactate transport in the brain. Therefore, the current studies investigated what effect exercise training or recurrent antecedent hypoglycemia had on MCT proteins in the VMH. Adult male Sprague-Dawley rats were used for both studies, randomized to receive either 6-7 weeks of aerobic training, sedentary behavior, 3 days of insulin induced hypoglycemia, or 3 days of saline injection. The increases in cytochrome c oxidase activity among the aerobically trained group showed that training adaptations occurred, however, there were no significant differences in MCT proteins within the VMH between the trained versus sedentary rats. While each of the 3 days of hypoglycemia or saline injection showed differences in 30 minute post-injection glucose concentrations, no significant differences in MCTs were observed in the VMH between the 2 groups on day 4

Obesity Indices Are Predictive Of Elevated C-Reactive Protein In Long-Haul Truck Drivers

BACKGROUND: Obesity rates in long-haul truck drivers have been shown to be significantly higher than the general population. We hypothesized that commercial drivers with the highest levels of general obesity and abdominal adiposity would have higher concentrations of high sensitivity C-reactive protein (CRP), a marker of inflammation

High-Intensity Exercise and Carbohydrate Supplementation do not Alter Plasma Visfatin

The purpose of the study was to examine the effect of high-intensity exercise and carbohydrate supplementation (CHO) on plasma visfatin. On 2 separate days, 10 sprint-trained males (age = 26.4 ± 5.3 yr; Ht = 1.77 ± 0.03 m; Wt = 78.78 ± 9.10 kg; BF% = 13.96 ± 7.28%) completed 4, 3-min bouts of cycling at 50% mean anaerobic power, with 6 min of rest between bouts. On CHO day, subjects ingested 50g of CHO 30 min before exercise. On control day, subjects ingested a sugar-free drink (CON) 30 min before exercise. Blood was drawn before supplementation, 15 min before exercise, before and after each exercise bout, and 15 and 30 min post exercise. Visfatin, glucose, and insulin were determined. Truncal fat was assessed by dual energy x-ray. Visfatin was not significantly different between treatments (CHO vs CON) at any time point (p = 0.163), and was not significantly altered by exercise (p = 0.692). Insulin [25.65 vs 8.35 mU/l, CHO vs CON, respectively] and glucose [138.57 vs 98.10 mg/dl, CHO vs CON, respectively] were significantly elevated after CHO ingestion and remained elevated throughout the first half of exercise. Baseline visfatin was significantly correlated with truncal fat (r2 = 0.7782, p < 0.05). Visfatin was correlated to truncal fat in sprint-trained males, but was not altered by exercise or CHO supplementation