Edmonton Obesity Staging System for Pediatrics, quality of life and fitness in adolescents with obesity.

BACKGROUND: Body mass index (BMI) is often used to diagnose obesity in childhood and adolescence but has limitations as an index of obesity-related morbidity. The Edmonton Obesity Staging System for Pediatrics (EOSS-P) is a clinical staging system that uses weight-related comorbidities to determine health risk in paediatric populations. The purpose of this study was to investigate the associations of EOSS-P and BMI percentile with quality of life (QOL), cardiorespiratory fitness (CRF) and muscular strength in adolescents with obesity. METHODS: Participants were enrolled at baseline in the Healthy Eating, Aerobic and Resistance Training in Youth trial (BMI = 34.6 ± 4.5 kg m-2, age = 15.6 ± 1.4 years, N = 299). QOL, CRF (peak oxygen uptake, VO2peak) and muscular strength were assessed by the Pediatric QOL Inventory (PedsQL), indirect calorimetry during a maximal treadmill test and eight-repetition maximum bench and leg press tests, respectively. Participants were staged from 0 to 3 (absent to severe health risk) according to EOSS-P. Associations were assessed using age-adjusted and sex-adjusted general linear models. RESULTS: Quality of life decreased with increasing EOSS-P stages (p < 0.001). QOL was 75.7 ± 11.4 in stage 0/1, 69.1 ± 13.1 in stage 2 and 55.4 ± 13.0 in stage 3. BMI percentile was associated with VO2peak (ß = -0.044 mlO2 kg-1 min-1 per unit increase in BMI percentile, p < 0.001), bench press (ß = 0.832 kg per unit increase in BMI percentile, p = 0.029) and leg press (ß = 3.992 kg, p = 0.003). There were no significant differences in treadmill time or VO2peak between EOSS-P stages (p > 0.05). CONCLUSION: As EOSS-P stages increase, QOL decreases. BMI percentile was negatively associated with CRF and positively associated with muscular strength.

Understanding low adherence to an exercise program for adolescents with obesity: the HEARTY trial.

INTRODUCTION: Despite efforts to improve adherence to physical activity interventions in youth with obesity, low adherence and attrition remain areas of great concern. OBJECTIVE: The study was designed to determine which physiological and/or psychological factors predicted low adherence in adolescents with obesity enrolled in a 6-month exercise intervention study aimed to improve body composition. METHODS: Three hundred four adolescents with obesity aged 14-18 years who volunteered for the HEARTY (Healthy Eating Aerobic and Resistance Training in Youth) randomized controlled trial completed physiological (body mass index, waist circumference, per cent body fat, resting metabolic rate and aerobic fitness) and psychological (body image, mood, self-esteem and self-efficacy) measures. RESULTS: One hundred forty-one out of 228 (62%) randomized to exercise groups had low adherence (completed <70% of the prescribed four exercise sessions per week) to the intervention protocol. Logistic regression revealed that there were no baseline demographic or physiological variables that predicted low adherence in the participants. Appearance concern (a subscale of body image) (odds ratio [OR] 1.46, 95% confidence interval [CI]: 1.01, 2.1, P = 0.04), depressive mood (OR 1.12, 95% CI: 1.01, 1.23, P = 0.03) and confused mood (OR 1.16, 95% CI: 1.05, 1.27, P = 0.003) (two subscales of mood) were significant predictors of low adherence. CONCLUSIONS: Adolescents with obesity who had higher appearance concerns and depressive and confused moods were less likely to adhere to exercise. Body image and mood should be screened to identify adolescents who may be at high risk of poor adherence and who may need concurrent or treatment support to address these psychological issues to derive maximal health benefits from an exercise programme.

Effects of aerobic and resistance training on abdominal fat, apolipoproteins and high-sensitivity C-reactive protein in adolescents with obesity: the HEARTY randomized clinical trial.

OBJECTIVES: To investigate the effects of aerobic training, resistance training, or both on abdominal subcutaneous fat (subcutaneous adipose tissue (SAT)) (deep and superficial), visceral fat (visceral adipose tissue (VAT)), apolipoproteins A-1 and B (ApoA-1, ApoB), ApoB/ApoA-1 ratio and high-sensitivity C-reactive protein (HSCRP) in post-pubertal adolescents with obesity. PARTICIPANTS: After a 4-week supervised moderate-intensity exercise run-in period, 304 postpubertal adolescents with overweight (body mass index (BMI) ⩾85th percentile for age and sex+diabetes risk factor) or obesity (⩾95th BMI percentile) aged 14-18 years were randomized to four groups for 22 weeks (5 months): aerobic training, resistance training, combined training or a non-exercising control. METHODS: This study used a randomized controlled design. All groups received dietary counseling designed to promote healthy eating with a maximum daily energy deficit of 250 kcal. Abdominal fat (SAT and VAT) at the level of the fourth and fifth lumbar vertebrae (L4-L5) was measured by magnetic resonance imaging and ApoA-1, ApoB and HSCRP were measured after a 12-h fast at baseline and after 6 months. RESULTS: Changes in SAT at L4-L5 were -16.2 cm(2) in aerobic (P=0.04 vs control), -22.7 cm(2) in resistance (P=0.009 vs control) and -18.7 cm(2) in combined (P=0.02 vs control). Combined training reduced ApoB levels from 0.81±0.02 to 0.78±0.02 g l(-1) (P=0.04 vs control) and ApoB/ApoA-1 ratio from 0.67±0.02 to 0.64±0.02 (P=0.02 vs control and P=0.04 vs aerobic). There were no significant differences in VAT, ApoA-1 or HSCRP levels between groups. CONCLUSIONS: Aerobic and resistance training and their combination decreased abdominal SAT in adolescents with obesity. Combined training caused greater improvements in ApoB/ApoA-1 ratio compared with aerobic training alone.

Effectiveness of cold water immersion for treating exertional heat stress when immediate response is not possible.

Immediate treatment with cold water immersion (CWI) is the gold standard for exertional heatstroke. In the field, however, treatment is often delayed due to delayed paramedic response and/or inaccurate diagnosis. We examined the effect of treatment (reduction of rectal temperature to 37.5 °C) delays of 5, 20, and 40 min on core cooling rates in eight exertionally heat-stressed (40.0 °C rectal temperature) individuals. We found that rectal temperature was elevated above baseline (P < 0.05) at the end of all delay periods (5 min: 40.08 ± 0.32; 20 min: 39.92 ± 0.40; 40 min: 39.57 ± 0.29 °C). Mean arterial pressure was reduced (P < 0.05) below baseline (92 ± 1.8 mm Hg) after all delay periods (5 min: 75 ± 2.6; 20 min: 74 ± 1.7; 40 min: 70 ± 2.1 mm Hg; P > 0.05). Rectal core cooling rates were similar among conditions (5 min: 0.20 ± 0.01; 20 min: 0.17 ± 0.02; 40 min: 0.17 ± 0.01 °C/min; P > 0.05). The rectal temperature afterdrop following CWI was similar across conditions (5 min: 35.95; 20 min: 35.61; 40 min: 35.87 °C; P > 0.05). We conclude that the effectiveness of 2 °C CWI as a treatment for exertional heat stress remains high even when applied with a delay of 40 min. Therefore, our results support that CWI is the most appropriate treatment for exertional heatstroke as it is capable of quickly reversing hyperthermia even when treatment is commenced with a significant delay.

Does type 1 diabetes alter post-exercise thermoregulatory and cardiovascular function in young adults?

Recent data demonstrated that individuals with type 1 diabetes mellitus (T1DM) exhibit impaired sweating and increased rectal temperature (i.e., heat storage) during exercise compared with healthy controls. Our purpose in this study was to investigate the consequences of T1DM on post-exercise thermal homeostasis. Sixteen participants (eight controls matched with eight T1DM) performed 90 min of cycling followed by 60 min of seated recovery. Esophageal and rectal temperatures, sweating (forearm, chest, and upper back), skin blood flow [forearm and upper back, presented as cutaneous vascular conductance (CVC)], and blood pressure [mean arterial pressure (MAP)] were measured at baseline and throughout recovery. Esophageal temperature was similar during baseline and recovery between groups (P = 0.88). However, rectal temperature was elevated in our T1DM group throughout recovery (P = 0.05). Sweating and CVC were similar between groups at all sites from 10-min post-exercise until the end of recovery (P ≥ 0.16). While absolute MAP was similar between groups (P = 0.43), the overall decrease in MAP post-exercise was greater in controls from 20 min (T1DM: - 8 ± 5 vs control: - 13 ± 6 mmHg, P = 0.03) until the end of recovery. We conclude that despite increased heat storage during exercise, individuals with T1DM exhibit a suppression in heat loss similar to their healthy counterparts during recovery.

A review of randomized controlled trials of aerobic exercise training on fitness and cardiometabolic risk factors in obese adolescents.

Aerobic training is the most prescribed exercise modality for the management of pediatric obesity. There is strong evidence that it decreases waist circumference, percent body fat and visceral fat, increases cardiorespiratory fitness, and decreases blood pressure in obese adolescents. However, the independent effects of aerobic exercise training on other cardiometabolic risk factors (ie, insulin resistance markers, plasma lipid levels, and inflammatory markers) are limited and yield inconsistent findings. Our article reviews randomized controlled trials evaluating the effects of aerobic exercise training on body composition, fitness, lipid levels, and insulin resistance in obese adolescents (aged 13-18 years) and outlines future research directions for this population.

Mean arterial pressure following prolonged exercise in the heat: influence of training status and fluid replacement.

Prolonged exercise in the heat without fluid replacement represents a significant challenge to the regulation of mean arterial pressure (MAP). It is unknown, however, if MAP is equally challenged during the post-exercise period, and whether regular endurance exercise training can provide any benefit to its regulation. We examined MAP (Finometer) in eight trained (T) and eight untrained (UT) individuals prior to, and following, 120 min of cycling at 42 °C with (HYD) and without (DEHY) fluid replacement. Exercise during DEHY induced significant hyperthermia (T: 39.20 ± 0.52 °C vs UT: 38.70 ± 0.36 °C, P = 0.941) and body weight losses (T: 3.4 ± 1.2% vs UT: 2.7 ± 0.9%, P = 0.332), which did not differ between groups. Although MAP was equally reduced 5 min into the post-exercise period of DEHY (T: -20 ± 11 mmHg vs UT: -22 ± 13 mmHg, P = 0.800), its subsequent recovery was significantly different between groups (P = 0.037). While MAP returned to pre-exercise values in UT (-1 ± 3 mmHg), it remained reduced in T (-9 ± 3 mmHg, P = 0.028). No differences in MAP post-exercise were observed between groups during HYD. These data suggest that trained men exhibit a greater level of post-exercise hypotension following prolonged exercise in the heat without fluid replacement. Furthermore, fluid replacement reverses the sustained post-exercise hypotension observed in trained individuals.

Healthy Eating, Aerobic and Resistance Training in Youth (HEARTY): study rationale, design and methods.

PURPOSE: The objective of the Healthy Eating Aerobic and Resistance Training in Youth (HEARTY) trial (ClinicalTrials.Gov # NCT00195858) was to examine the effects of resistance training, with and without aerobic training, on percent body fat in sedentary, post-pubertal overweight or obese adolescents aged 14-18 years. This paper describes the HEARTY study rationale, design and methods. METHODS: After a 4-week supervised low-intensity exercise run-in period, 304 overweight or obese adolescents with a body mass index≥85th percentile for age and sex were randomized to 4 groups for 22 weeks (5 months): diet+aerobic exercise, diet+resistance exercise, diet+combined aerobic and resistance exercise, or a diet only waiting-list control. All participants received dietary counseling designed to promote healthy eating with a maximum daily energy deficit of -250 kcal. OUTCOMES: The primary outcome is percent body fat measured by Magnetic Resonance Imaging. Secondary outcomes include changes in anthropometry, regional body composition, resting energy expenditure, cardiorespiratory fitness, musculoskeletal fitness, cardiometabolic risk markers, and psychological health. SUMMARY: To our knowledge, HEARTY is the largest clinical trial examining effects of aerobic training, resistance training, and combined aerobic and resistance training on changes in adiposity and cardiometabolic risk markers in overweight and obese adolescents. The findings will have important clinical implications regarding the role that resistance training should play in the management of adolescent obesity and its co-morbidities.

Overweight and obese teenagers: why is adolescence a critical period?

This paper discusses the critical period of adolescence and its potential role in the development and persistence of obesity. The adolescent years are characteristic of changes in body composition (location and quantity of body fat), physical fitness and decreased insulin sensitivity during puberty. This period of growth and maturation is also marked with behavioural changes in diet, physical activity, sedentary behaviour and psychological health. Physical activity and sport participation decline during adolescence especially in teenage girls, while sedentary behaviour, risk for depression and body esteem issues increase during the teenage years. These physiological and behavioural changes during adolescence warrant the attention of health practitioners to prevent the onset and continuation of obesity throughout the lifespan.

Comparison of strength development with resistance training and combined exercise training in type 2 diabetes.

Resistance training has been shown to increase strength in type 2 diabetes; however, it is unclear if combining resistance and aerobic training (A + R) impedes strength development compared with resistance training only (R). The purpose of this study was to compare changes in strength with A + R vs R in individuals with type 2 diabetes. We evaluated monthly workload increments in participants from the Diabetes Aerobic and Resistance Exercise clinical trial. Muscular strength was assessed through training volumes and as the eight repetition maximum (8-RM) at 0, 3, and 6 months. Both groups increased their upper and lower body volumes monthly for 6 months. The relative increase in upper body workload in R was significantly greater than A + R at 4 months (161 ± 11% vs 127 ± 11%, P = 0.009) and at 6 months of training (177 ± 11% vs 132 ± 11%, P = 0.008). Both groups had improvements in 8-RM workloads at 3 and 6 months. The resistance training group had a significantly greater improvement in 8-RM on the leg press at 6 months compared with A + R (80 ± 11% vs 58 ± 8%, P = 0.045). Both R and A + R improved strength with a 6-month training program; however, increases in strength may be greater with resistance training alone compared with performing both aerobic and resistance training.

Associations between physical fitness and HbA1(c) in type 2 diabetes mellitus.

AIM/HYPOTHESIS: In people with type 2 diabetes, exercise improves glucose control (as reflected in HbA1(c)) and physical fitness, but it is not clear to what extent these exercise-induced improvements are correlated with one another. We hypothesised that reductions in HbA1(c) would be related: (1) to increases in aerobic fitness and strength respectively in patients performing aerobic training or resistance training; and (2) to changes in strength and aerobic fitness in patients performing aerobic and resistance training. METHODS: We randomly allocated 251 type 2 diabetes patients to aerobic, resistance, or aerobic plus resistance training, or to a sedentary control group. Peak oxygen consumption VO2(peak), workload, treadmill time and ventilatory threshold measurements from maximal treadmill exercise testing were measured at baseline and 6 months. Muscular strength was measured as the maximum weight that could be lifted eight times on the leg press, bench press and seated row exercises. RESULTS: With aerobic training, significant associations were found between changes in both VO2(peak) (p = 0.040) and workload (p = 0.022), and changes in HbA1(c.) With combined training, improvements in VO2(peak) (p = 0.008), workload (p = 0.034) and ventilatory threshold (p = 0.003) were significantly associated with changes in HbA1(c.) Increases in strength on the seated row (p = 0.006) and in mid-thigh muscle cross-sectional area (p = 0.030) were significantly associated with changes in HbA1(c) after resistance exercise, whereas the association between increases in muscle cross-sectional area and HbA1(c) in participants doing aerobic plus resistance exercise (p = 0.059) was of borderline significance. CONCLUSIONS/INTERPRETATION: There appears to be a link between changes in fitness and HbA1(c). The improvements in cardiorespiratory fitness with aerobic training may be a better predictor of changes in HbA1(c) than improvements in strength.

Effects of aerobic exercise, resistance exercise or both, on patient-reported health status and well-being in type 2 diabetes mellitus: a randomised trial.

AIMS/HYPOTHESIS: The Diabetes Aerobic and Resistance Exercise (DARE) study showed that aerobic and resistance exercise training each improved glycaemic control and that a combination of both was superior to either type alone in patients with type 2 diabetes mellitus. Here we report effects on patient-reported health status and well-being in the DARE Trial. METHODS: We randomised 218 inactive participants with type 2 diabetes mellitus in parallel to 22 weeks of aerobic exercise (n = 51), resistance exercise (n = 58), combined aerobic and resistance exercise (n = 57) or no exercise (control; n = 52). Intervention allocation was managed by a central office. Outcomes included health status as assessed by the physical and mental component scores of the Medical Outcomes Trust Short-Form 36-item version (SF-36) and well-being as measured by the Well-Being Questionnaire 12-item version (WBQ-12); these were measured at the Ottawa Hospital. RESULTS: Using a p value of 0.0125 for statistical significance due to multiple comparisons, mixed model analyses indicated that resistance exercise led to clinically but not statistically significant improvements in the SF-36 physical component score compared with aerobic exercise (Delta = 2.7 points; p = 0.048) and control (i.e. no exercise; Delta = 3.3 points; p = 0.015). For mental component scores, there were clinically important improvements favouring no (control) compared with resistance (Delta = 7.6 points; p < 0.001) and combined (Delta = 7.2 points; p < 0.001) exercise. No effects on WBQ-12 scores were noted. Overall, 59/218 (27%) of participants included in this analysis sustained an adverse event during the course of the study, including 16 participants in the combined exercise group, 19 participants in the resistance exercise group, 16 participants in the aerobic exercise group, and eight participants in the control group. All participants were included in the intent-to-treat analyses. The trial is now closed to follow-up. CONCLUSIONS/INTERPRETATION: Resistance exercise was better than aerobic or no exercise for improving physical health status in these patients. No exercise was superior to resistance or combined exercise for improving mental health status. Well-being was unchanged by intervention. TRIAL REGISTRATION: ClinicalTrials.gov NCT00195884 FUNDING: This study was funded by the Canadian Institutes of Health Research (grant MCT-44155) and the Canadian Diabetes Association (The Lillian Hollefriend Grant).

Safe cooling limits from exercise-induced hyperthermia.

We evaluated the cooling rate of hyperthermic subjects, as measured by three estimates of deep core temperatures (esophageal, rectal and aural canal temperatures), during immersion in a range of water temperatures. The objective of the study was to compare the three indices of core temperature and define safe cooling limits when using rectal temperature to avoid the development of hypothermia. On 4 separate days, seven subjects (four males, three females) exercised for 45.4+/-4.1 min at 65% V(O2)max at an ambient temperature of 39 degrees C, RH: 36.5%, until rectal temperature (T (re)) increased to 40.0 degrees C (39.5 degrees C for two subjects). Following exercise, the subjects were immersed in a circulated water bath controlled at 2, 8, 14 and 20 degrees C until T (re) returned to 37.5 degrees C. When T (re) reached normothermia during the cooling period (37.5+/-0.05 degrees C), both esophageal (T (es)) (35.6+/-1.3 degrees C) and aural canal (T (ac)) (35.9+/-0.9 degrees C) temperatures were approaching or reaching hypothermia, particularly during immersion in 2 degrees C water (T (es)=34.5+/-1.2 degrees C). On the basis of the heat loss data, the heat gained during the exercise was fully eliminated after 5.4+/-1.5, 7.9+/-2.9, 10.4+/-3.8 and 13.1+/-2.8 min of immersion in 2, 8, 14 and 20 degrees C water, respectively, with the coldest water showing a significantly faster cooling rate. During the immersion in 2 degrees C water, a decrease of only 1.5 degrees C in T (re) resulted in the elimination of 100% of the heat gained during exercise without causing hypothermia. This study would therefore support cooling the core temperature of hyperthermic subjects to a rectal temperature between 37.8 degrees C (during immersion in water >10 degrees C) and 38.6 degrees C (during immersion in water <10 degrees C) to eliminate the heat gained during exercise without causing hypothermia.

Meta-analysis of the effect of structured exercise training on cardiorespiratory fitness in Type 2 diabetes mellitus.

AIMS/HYPOTHESIS: Low cardiorespiratory fitness is a powerful and independent predictor of mortality in people with diabetes. Several studies have examined the effects of exercise on cardiorespiratory fitness in Type 2 diabetic individuals. However, these studies had relatively small sample sizes and highly variable results. Therefore the aim of this study was to systematically review and quantify the effects of exercise on cardiorespiratory fitness in Type 2 diabetic individuals. METHODS: MEDLINE, EMBASE, and four other databases were searched up to March 2002 for randomized, controlled trials evaluating effects of structured aerobic exercise interventions of 8 weeks or more on cardiorespiratory fitness in adults with Type 2 diabetes. Cardiorespiratory fitness was defined as maximal oxygen uptake (VO(2max)) during a maximal exercise test. RESULTS: Seven studies, presenting data for nine randomized trials comparing exercise and control groups (overall n=266), met the inclusion criteria. Mean exercise characteristics were as follows: 3.4 sessions per week, 49 min per session for 20 weeks. Exercise intensity ranged from 50% to 75% of VO(2max). There was an 11.8% increase in VO(2max) in the exercise group and a 1.0% decrease in the control group (post intervention standardized mean difference =0.53, p<0.003). Studies with higher exercise intensities tended to produce larger improvements in VO(2max). Exercise intensity predicted post-intervention weighted mean difference in HbA(1c) (r=-0.91, p=0.002) to a larger extent than did exercise volume (r=-0.46, p=0.26). CONCLUSIONS/INTERPRETATION: Regular exercise has a statistically and clinically significant effect on VO(2max) in Type 2 diabetic individuals. Higher intensity exercise could have additional benefits on cardiorespiratory fitness and HbA(1c).

Effect of water temperature on cooling efficiency during hyperthermia in humans.

We evaluated the cooling rate of hyperthermic subjects, as measured by rectal temperature (T(re)), during immersion in a range of water temperatures. On 4 separate days, seven subjects (4 men, 3 women) exercised at 65% maximal oxygen consumption at an ambient temperature of 39 degrees C until T(re) increased to 40 degrees C (45.4 +/- 4.1 min). After exercise, the subjects were immersed in a circulated water bath controlled at 2, 8, 14, or 20 degrees C until T(re) returned to 37.5 degrees C. No difference in cooling rate was observed between the immersions at 8, 14, and 20 degrees C despite the differences in the skin surface-to-water temperature gradient, possibly because of the presence of shivering at 8 and 14 degrees C. Compared with the other conditions, however, the rate of cooling (0.35 +/- 0.14 degrees C/min) was significantly greater during the 2 degrees C water immersion, in which shivering was seldom observed. This rate was almost twice as much as the other conditions (P < 0.05). Our results suggest that 2 degrees C water is the most effective immersion treatment for exercise-induced hyperthermia.

Muscle temperature transients before, during, and after exercise measured using an intramuscular multisensor probe.

Seven subjects (1 woman) performed an incremental isotonic test on a Kin-Com isokinetic apparatus to determine their maximal oxygen consumption during bilateral knee extensions (Vo(2 sp)). A multisensor thermal probe was inserted into the left vastus medialis (middiaphysis) under ultrasound guidance. The deepest sensor (tip) was located approximately 10 mm from the femur and deep femoral artery (T(mu 10)), with additional sensors located 15 (T(mu 25)) and 30 mm (T(mu 40)) from the tip. Esophageal temperature (T(es)) was measured as an index of core temperature. Subjects rested in an upright seated position for 60 min in an ambient condition of 22 degrees C. They then performed 15 min of isolated bilateral knee extensions (60% of Vo(2 sp)) on a Kin-Com, followed by 60 min of recovery. Resting T(es) was 36.80 degrees C, whereas T(mu 10), T(mu 25), and T(mu 40) were 36.14, 35.86, and 35.01 degrees C, respectively. Exercise resulted in a T(es) increase of 0.55 degrees C above preexercise resting, whereas muscle temperature of the exercising leg increased by 2.00, 2.37, and 3.20 degrees C for T(mu 10), T(mu 25), and T(mu 40), respectively. Postexercise T(es) showed a rapid decrease followed by a prolonged sustained elevation approximately 0.3 degrees C above resting. Muscle temperature decreased gradually over the course of recovery, with values remaining significantly elevated by 0.92, 1.05, and 1.77 degrees C for T(mu 10), T(mu 25), and T(mu 40), respectively, at end of recovery (P < 0.05). These results suggest that the transfer of residual heat from previously active musculature may contribute to the sustained elevation in postexercise T(es).

Effects of exercise on glycemic control and body mass in type 2 diabetes mellitus: a meta-analysis of controlled clinical trials.

CONTEXT: Exercise is widely perceived to be beneficial for glycemic control and weight loss in patients with type 2 diabetes. However, clinical trials on the effects of exercise in patients with type 2 diabetes have had small sample sizes and conflicting results. OBJECTIVE: To systematically review and quantify the effect of exercise on glycosylated hemoglobin (HbA(1c)) and body mass in patients with type 2 diabetes. DATA SOURCES: Database searches of MEDLINE, EMBASE, Sport Discuss, Health Star, Dissertation Abstracts, and the Cochrane Controlled Trials Register for the period up to and including December 2000. Additional data sources included bibliographies of textbooks and articles identified by the database searches. STUDY SELECTION: We selected studies that evaluated the effects of exercise interventions (duration >/=8 weeks) in adults with type 2 diabetes. Fourteen (11 randomized and 3 nonrandomized) controlled trials were included. Studies that included drug cointerventions were excluded. DATA EXTRACTION: Two reviewers independently extracted baseline and postintervention means and SDs for the intervention and control groups. The characteristics of the exercise interventions and the methodological quality of the trials were also extracted. DATA SYNTHESIS: Twelve aerobic training studies (mean [SD], 3.4 [0.9] times/week for 18 [15] weeks) and 2 resistance training studies (mean [SD], 10 [0.7] exercises, 2.5 [0.7] sets, 13 [0.7] repetitions, 2.5 [0.4] times/week for 15 [10] weeks) were included in the analyses. The weighted mean postintervention HbA(1c) was lower in the exercise groups compared with the control groups (7.65% vs 8.31%; weighted mean difference, -0.66%; P<.001). The difference in postintervention body mass between exercise groups and control groups was not significant (83.02 kg vs 82.48 kg; weighted mean difference, 0.54; P =.76). CONCLUSION: Exercise training reduces HbA(1c) by an amount that should decrease the risk of diabetic complications, but no significantly greater change in body mass was found when exercise groups were compared with control groups.

Acute head-down tilt decreases the postexercise resting threshold for forearm cutaneous vasodilation.

The purpose of this study was to evaluate the role of baroreceptor control on the postexercise threshold for forearm cutaneous vasodilation. On four separate days, six subjects (1 woman) were randomly exposed to 65 degrees head-up tilt and to 15 degrees head-down tilt during a No-Exercise and Exercise treatment protocol. Under each condition, a whole body water-perfused suit was used to regulate mean skin temperature (T(sk)) in the following sequence: 1) cooling until the threshold for vasoconstriction was evident; 2) heating ( approximately 7.0 degrees C/h) until vasodilation occurred; and 3) cooling until esophageal temperature (T(es)) and (T(sk)) returned to baseline values. The Exercise treatment consisted of 15 min of cycling exercise at 70% maximal O(2) uptake, followed by 15 min of recovery in the head-up tilt position. The No-Exercise treatment consisted of 30 min resting in the head-up tilt position. After the treatment protocols, subjects were returned to their pretreatment condition, then cooled and warmed again consecutively. The calculated T(es) threshold for cutaneous vasodilation increased 0.24 degrees C postexercise during head-up tilt (P < 0.05), whereas no difference was measured during head-down tilt. In contrast, sequential measurements without exercise demonstrate a time-dependent decrease for head-up tilt (0.17 degrees C) and no difference for head-down tilt. Pretreatment thresholds were significantly lower during head-down tilt compared with head-up tilt. We have shown that manipulating postexercise venous pooling by means of head-down tilt, in an effort to reverse its impact on baroreceptor unloading, resulted in a relative lowering of the resting postexercise elevation in the T(es) for forearm cutaneous vasodilation.

Moderate exercise increases the post exercise resting warm thermoregulatory response thresholds.

BACKGROUND: The purpose of this study was to evaluate the effect of exercise on the subsequent post-exercise core temperature thresholds for vasodilation and sweating. METHODS: On two separate days, with 6 subjects (3 males and 3 females), a whole-body water-perfused suit decreased mean skin temperature until the threshold for vasoconstriction was demonstrated. Mean skin temperature was then slowly increased (approximately 5.0 degrees C x h(-1)) until thresholds for vasodilation and sweating were clearly established. Subjects were cooled by decreasing water temperature until both esophageal and mean skin temperatures returned to near baseline values. Subjects then either performed 15 min of cycle ergometry (60% V(O2max)) followed by 30 min of recovery (Exercise), or remained seated with no exercise for 45 min (Control). Subjects were then cooled again until the onset of cutaneous vasoconstriction followed by a second warming period. The core temperature thresholds for vasodilation and sweating increased significantly by 0.49 degrees C and 0.19 degrees C post-exercise, respectively (p < 0.05). In order to compare thresholds between conditions in which both esophageal and mean skin temperatures were changing, we mathematically compensated for changes in skin temperatures using the established linear cutaneous contribution of skin to the control of vasodilation and sweating (10%). RESULTS: The calculated core temperature threshold (at a designated skin temperature of 36.0 degrees C) for vasodilation increased significantly from 36.56 +/- 0.12 degrees C to 37.11 +/- 0.21 degrees C post-exercise (p < 0.01). Likewise, the sweating threshold increased from 36.79 +/- 0.18 degrees C to 37.05 +/- 0.23 degrees C postexercise (p < 0.01). In contrast, sequential measurements, without exercise, demonstrate a time-dependent decrease (0.18 degrees C) in the sweating threshold, with no difference in the vasodilation threshold. CONCLUSION: These data indicate that exercise has a prolonged effect by increasing the post-exercise thresholds for both warm thermoregulatory responses.