Cardiorespiratory Fitness Is Impaired in Type 1 and Type 2 Diabetes: A Systematic Review, Meta-Analysis, and Meta-Regression.

INTRODUCTION: Low cardiorespiratory fitness (CRF) increases the risk of cardiovascular disease by up to 8-fold, and is one of the strongest predictors of mortality. Some studies demonstrate impaired CRF in people living with type 1 and type 2 diabetes compared to those without diabetes, while others demonstrate no diabetes-associated impairment in CRF. PURPOSE: We aimed to determine whether diabetes can influence CRF, and if so, identify clinical associations underlying diabetes-associated exercise impairments. METHODS: 68 studies were included in the quantitative analysis. Standardized mean difference (SMD) was calculated and meta-analyses and meta-regressions were performed by using a random-effects model. RESULTS: Diabetes is associated with a large negative effect on CRF (SMD = -0.80; p < 0.001)- an effect that is partially mitigated, but still significant, in those with high physical activity levels (SMD = -0.50; p = 0.007). A sedentary lifestyle (SMD = -0.83; p = 0.007), and the presence of clinical complications related to diabetes (SMD = -1.66; p < 0.001) predict a greater magnitude of CRF reduction in people with diabetes compared to controls without diabetes. Both type 1 and type 2 diabetes are independently associated with impaired CRF compared to controls without diabetes; however, the effect is significantly greater in those type 2 diabetes (SMD = -0.97; p < 0.001). Meta-regression analysis demonstrates the effects of diabetes on CRF are primarily associated with HbA1c levels for type 1 diabetes (B = -0.07; p < 0.001) and body mass index for type 2 diabetes (B = -0.17; p = 0.005). CONCLUSIONS: These data demonstrate a negative influence of diabetes on the key risk factor of low CRF and provide critical insight into specific clinical markers of low CRF associated with diabetes.

Low Response to Aerobic Training in Metabolic Disease: Role of Skeletal Muscle.

Aerobic exercise is established to increase cardiorespiratory fitness (CRF), which is linked to reduced morbidity and mortality. However, people with metabolic diseases such as type 1 and type 2 diabetes may be more likely to display blunted improvements in CRF with training. Here, we present evidence supporting the hypothesis that altered skeletal muscle signaling and remodeling may contribute to low CRF with metabolic disease.

Mild obesity does not affect the forearm muscle microvascular responses to hyperglycemia.

INTRODUCTION: Mild obesity has been associated with postprandial brachial artery vascular dysfunction. However, direct assessment of these effects within the forearm skeletal muscle microcirculation remains unclear. Thus, this study aimed to investigate the effects of mild obesity on the arm micro- and macrovascular responses to glucose ingestion. METHODS: This cross-sectional study combined NIRS assessments of forearm skeletal muscle (FDS) reactivity (reperfusion slope) with %FMD of conduit artery function (brachial artery) before (Pre), as well as 60 and 120 min after glucose ingestion in 10 lean (BMI 23.9 ± 1.8) and 10 obese (BMI 32.9 ± 1.9) individuals. RESULTS: Both groups showed a significant increase in the reperfusion slope at 60 and 120 min after glucose ingestion compared with the pre-glucose ingestion measurements. Obese individuals showed a significant (p < .05) reduction in %FMD at 60 min after glucose ingestion, while no significant changes in postprandial %FMD were observed in lean participants. CONCLUSION: Even though obese individuals showed impaired postprandial brachial artery function, the current findings suggest that mild obesity does not affect the forearm skeletal muscle responses to glucose ingestion.

Acute Photobiomodulation Does Not Influence Specific High-Intensity and Intermittent Performance in Female Futsal Players.

The acute improvement of performance after photobiomodulation therapy (PBMT) has been reported in different types of exercise. However, the effect on high-intensity and intermittent exercises that are relevant for team sports is unknown. Thus, we evaluated the effect of prior acute application of PBMT on high-intensity and intermittent exercise performance, muscle oxygenation, and physiological/perceptual indicators in amateur female futsal players. Thirteen players (24.1 ± 3.7 years) performed a testing battery (countermovement jump (CMJ), Illinois agility and YoYo intermittent recovery test level 1 (YYIR1)) preceded by 15 min of PBMT (1 min 30 s each muscular point; five muscular points in each lower limbs) or 15 min of placebo (SHAM), in a counterbalanced randomized cross-over design (one-week in-between PBMT/SHAM). All test performance did not differ (p > 0.05) between PBMT and SHAM, as well as blood lactate, rating of perceived exertion, heart rate, and muscle oxygenation (via near infrared spectroscopy) responses. The acute application of PBMT prior to a physical testing battery does not influence high-intensity and intermittent exercises performance, neither physiological nor perceptual responses in amateur female futsal players.

The effects of the analysis strategy on the correlation between the NIRS reperfusion measures and the FMD response.

This study aimed to investigate the correlation between near-infrared spectroscopy (NIRS)-derived measures of microvascular responses using a range of different analysis and flow-mediated dilation (FMD). Additionally, we aimed to investigate whether assessing NIRS and FMD simultaneously or non-simultaneously would affect this association. Thirty-five healthy young individuals (26 ±â€¯13 years old) participated in the study. Twenty were submitted to a simultaneous NIRS/FMD test (NIRS probe placed below the cuff during FMD test) and fifteen to a non-simultaneous FMD and NIRS intervention (NIRS test performed 20 min after FMD). NIRS-derived oxygen saturation signal (StO2) during reperfusion was analyzed as follow: upslope of a 10 s (slope 10 s) and 30 s (slope 30 s) reperfusion window immediately following cuff deflation, time for the StO2 to reach the pre-occlusion (baseline) values after cuff release (time to baseline) and to reach the peak after cuff release (time to max), difference between the minimum and maximum StO2 value reached after cuff deflation (Magnitude) and; the total area under the reperfusion curve above the baseline value until the end of the 2 min post cuff release (AUC 2 min). There was a significant positive correlation between slope 10 s and FMD in the simultaneous (r = 0.60; p < 0.05) and non-simultaneous (r = 0.62; p < 0.05) assessments. There was no significant correlation between NIRS-derived slope 30 s, time to baseline, time to max, magnitude, and AUC 2 min and the FMD in both methods. The association between NIRS and FMD is analysis strategy dependent, regardless if assessed simultaneously or non-simultaneously.

The effects of aging and cardiovascular risk factors on microvascular function assessed by near-infrared spectroscopy.

This study aimed to evaluate whether NIRS-derived reperfusion rate would detect potential differences in the forearm microvascular responsiveness between young healthy adults, and older adults free from or with cardiovascular disease (CVD) risk factors. Fifteen healthy young (age: 24.8 ±â€¯4.0 years), seventeen older adults free of CVD risk factors (age: 67.0 ±â€¯6.8 years), and twenty-three older adults with CVD risk factors (age: 67.9 ±â€¯8.0 years) participated this study. Individuals underwent a blood draw and vascular occlusion test (30 s of baseline, 5 min of occlusion, and 2 min of reperfusion) and microvascular responsiveness was evaluated by using NIRS-derived tissue oxygen saturation indexes during reperfusion. A significant slower reperfusion rate and lower reperfusion magnitude was observed in older adults with CVD risk factors compared to healthy young and older adults. Although no statistical differences were found between healthy young and older individuals, there was a small (d = 0.4) effect size for reperfusion rate and moderate (d = 0.7) effects size for reperfusion magnitude when comparing these groups. In conclusion, this study demonstrated that even though the effects of aging per se on microvascular function should not be completely neglected, the CVD risk factors seem to be determinant on microvascular responsiveness impairment associated with aging.

The association between near-infrared spectroscopy assessment of microvascular reactivity and flow-mediated dilation is disrupted in individuals at high risk for cardiovascular disease.

OBJECTIVE: This study aimed to evaluate the correlation between the NIRS-derived reperfusion slope and %FMD in the arm of healthy and at high risk for CVD individuals. METHODS: Twelve healthy (24 ± 4 years) and twelve at high risk for cardiovascular disease (65 ± 11 years) individuals participated in the study. The individuals were submitted to a conduit artery FMD followed by a NIRS-VOT microvascular function test in the arm. Microvascular responsiveness was calculated as the forearm reperfusion slope, and macrovascular function was assessed as the percent of change in FMD (%FMD) of the brachial artery. RESULTS: There was a significant correlation between reperfusion slope and %FMD (R = 0.61, P < 0.05) in the healthy group; however, no significant correlation between FMD and reperfusion slope (R = -0.21, P > 0.05) was found in individuals at high risk for CVD. CONCLUSION: The correlation between NIRS-derived reperfusion slope and %FMD was disrupted in the arm of individuals at high risk for cardiovascular disease compared to healthy individuals. The findings of the present study reinforce the importance of examining vascular function at microvasculature and conduit artery level, especially in populations with risk factors for CVD.

Noninvasive and in vivo assessment of upper and lower limb skeletal muscle oxidative metabolism activity and microvascular responses to glucose ingestion in humans.

This study investigated changes in muscle oxidative metabolism and microvascular responsiveness induced by glucose ingestion in the upper and lower limbs using near-infrared spectroscopy (NIRS). Fourteen individuals (aged 27 ± 1.4 years) underwent 5 vascular occlusion tests (VOT) (pre-intervention (Pre), 30 min, 60 min, 90 min, and 120 min after glucose challenge). NIRS-derived oxygen saturation (StO2) was measured on the forearm and leg muscle at each VOT. Muscle oxidative metabolism was determined by the StO2 downslope during cuff inflation (deoxygenation slope); microvascular responsiveness was estimated by the StO2 upslope (reperfusion slope) following cuff deflation. There was a significant increase in arm (p < 0.05; 1-ß = 0.860) and leg (p < 0.05; 1-ß = 1.000) oxidative metabolism activity as represented by the faster deoxygenation slope at 60, 90, and 120 min (0.08 ± 0.03, 0.08 ± 0.03, 0.08 ± 0.02%·s-1, respectively) (leg) and at 90 min (0.16 ± 0.08%·s-1) (arm) observed after glucose ingestion when compared with their respective Pre values (leg = 0.06 ± 0.02; arm = 0.11 ± 0.04%·s-1). There was a significant increase in arm (p < 0.05; 1-ß = 0.880) and leg (p < 0.05; 1-ß = 0.983) reperfusion slope at 60 min (arm = 3.63 ± 2.1%·s-1; leg = 1.56 ± 0.6%·s-1), 90 min (arm = 3.91 ± 2.1%·s-1; leg = 1.60 ± 0.6%·s-1), and 120 min (arm = 3.91 ± 1.6%·s-1; leg = 1.54 ± 0.6%·s-1) when compared with their Pre values (arm = 2.79 ± 1.7%·s-1; leg = 1.26 ± 0.5%·s-1). Our findings showed that NIRS-VOT technique is capable of detecting postprandial changes in muscle oxidative metabolism activity and microvascular reactivity in the upper and lower limb. Novelty NIRS-VOT is a promising noninvasive clinical approach that may help in the early, limb-specific detection of impairments in glucose oxidation and microvascular function.

Differences in vascular function between trained and untrained limbs assessed by near-infrared spectroscopy.

PURPOSE: The aim of this study was to examine whether differences in vascular responsiveness associated with training status would be more prominent in the trained limb (leg) than in the untrained limb (arm) microvasculature. METHODS: Thirteen untrained (26 ± 5 year) and twelve trained (29 ± 4 year) healthy men were submitted to a vascular occlusion test (VOT) (2 min baseline, 5 min occlusion, and 8 min re-oxygenation). The oxygen saturation signal (StO2) was assessed using near-infrared spectroscopy (NIRS) throughout the VOT. Vascular responsiveness within the microvasculature was evaluated by the re-oxygenation Slope 2 (Slope 2 StO2) and the area under the curve (StO2AUC) of (StO2) signal during re-oxygenation in the leg and arm. RESULTS: There was a significant interaction between training status and limb for the slope 2 StO2 (P < 0.01). The leg of the trained group showed a steeper slope 2 StO2 (1.35 ± 0.12% s-1) when compared to the slope 2 StO2 of the leg in their untrained counterparts (0.86 ± 0.09% s-1) (P < 0.05). There was a medium effect size of 0.58 for slope 2 StO2 on the arm and a large effect size of 1.21 for slope 2 StO2 on the leg. In addition, there was a small effect size of 0.24 for StO2AUC on the arm and a medium effect size of 0.64 for StO2AUC on the leg. CONCLUSION: The present study suggests that the vascular adaptations induced by lower limb endurance exercise training are more prominent in the trained limb than in the untrained limb microvasculature.

The influence of CYP1A2 genotype in the blood pressure response to caffeine ingestion is affected by physical activity status and caffeine consumption level.

This study aimed to investigate whether the influence of CYP1A2 genotype in the blood pressure (BP) response to caffeine ingestion was affected by physical activity status and habitual caffeine consumption. Thirty-seven participants (19-50 years old) took place in the study and were categorized according to i) genotype: CYP1A2 (AA) "fast metabolizer", and CYP1A2 (AC) "slow metabolizer"; ii) physical activity level: sedentary (S) and physically active (A); and iii) caffeine consumption level: non-habitual caffeine consumer (NC) and habitual heavy caffeine consumer (C). All groups had BP assessed before (basal) and 1 hourh after (post) caffeine ingestion (6 mg·kg-1). It was observed that AC genotype individuals had increased basal-DBP and post-caffeine SBP when compared to AA individuals. Additionally, acute caffeine ingestion increased SBP only in the AC group. It was also found that physical activity only modulated the BP responses to acute caffeine ingestion in AC individuals. Furthermore, the results indicated that the habitual heavy caffeine consumers AC individuals had increased basal-DBP when compared to the AA ones. Our results suggest that the influence of CYP1A2 genotype in the basal and post-caffeine BP response to caffeine ingestion is modified by physical activity status and caffeine consumption level.

Near-infrared spectroscopy assessment of microvasculature detects difference in lower limb vascular responsiveness in obese compared to lean individuals.

BACKGROUND: Microvascular dysfunction is an early complication in obesity-related cardiovascular disease (CVD) that can lead to changes in hemodynamic function and endothelial cell expression throughout the vasculature that is vessel specific. This study aimed to evaluate whether the near-infrared spectroscopy (NIRS) combined with a vascular occlusion (VOT) assessment was capable of detecting differences in vascular responsiveness within the microvasculature of the lower limb between lean and obese individuals. METHODS AND RESULTS: Twenty lean (BMI = 21.6 ±â€¯1.3) and 17 obese individuals (BMI = 33.9 ±â€¯1.1) participated in the study. Individuals underwent a VOT (5 min of baseline, 5 min of occlusion, and 8 min following cuff release) and vascular responsiveness was evaluated by the Slope 2 (Slope 2 StO2) and the area under the curve (StO2AUC) of oxygen saturation (StO2) signal during reperfusion. The difference between the minimal and the maximal value of StO2 was calculated as the Amplitude of the StO2 response. The Slope 2 StO2 of the obese individuals was smaller (0.68 ±â€¯0.07%·s-1) than the Slope 2 StO2 of the lean individuals (1.08 ±â€¯0.13%·s-1;P < 0.05). The StO2AUC of the obese was smaller (978 ±â€¯169%·s-1) than the StO2AUC of the lean individuals (1708 ±â€¯168%·s-1; P < 0.001). The amplitude of StO2 was smaller in obese individuals than the lean ones (30.4 ±â€¯2.9 vs 21.6 ±â€¯1.3 StO2 (%), respectively; P < 0.05). There was a significant correlation between Slope 2 StO2 and StO2AUC for lean individuals (r = 0.745; P < 0.001). CONCLUSION: This study demonstrated differences in vascular responses within the microvasculature of the lower limb between lean and obese individuals.

Near-infrared spectroscopy can detect differences in vascular responsiveness to a hyperglycaemic challenge in individuals with obesity compared to normal-weight individuals.

OBJECTIVE: To examine whether the near-infrared spectroscopy combined with vascular occlusion test technique could detect differences in vascular responsiveness during hyperglycaemia between normal-weight individuals and individuals with obesity. METHODS: A total of 16 normal-weight individuals (body mass index, 21.3 ± 1.7 kg/m2) and 13 individuals with obesity (body mass index, 34.4 ± 2.0 kg/m2) were submitted to five vascular occlusion tests (Pre, 30, 60, 90 and 120 min after glucose challenge). Vascular responsiveness was determined by the Slope 2 (Slope 2 StO2) and the area under the curve (StO2AUC) of oxygen saturation derived from near-infrared spectroscopy-vascular occlusion test. RESULTS: The Slope 2 StO2 increased from 1.07 ± 0.16%/s (Pre) to 1.53 ± 0.21%/s at 90 min ( p < 0.05) in the control group, while in obese it increased from 0.71 ± 0.09%/s (Pre) to 0.92 ± 0.14%/s at 60 min ( p < 0.05), and to 0.97 ± 0.10%/s ( p < 0.01) at 120 min after glucose ingestion. The StO2AUC decreased from 1729 ± 214% . sec (Pre) to 1259 ± 232% . sec at 60 min ( p < 0.05) and to 1034 ± 172% . sec at 90 min ( p < 0.05) in the normal-weight group, whereas it decreased at 90 min (637 ± 98% . sec; p < 0.05) and at 120 min (590 ± 93% . sec; p < 0.01) compared to 30 min (1232 ± 197% . sec) after glucose ingestion in individuals with obesity. CONCLUSION: Near-infrared spectroscopy-vascular occlusion test technique was capable of detecting differences in vascular responsiveness during hyperglycaemia between normal-weight individuals and individuals with obesity.

Metabolic inflexibility in individuals with obesity assessed by near-infrared spectroscopy.

OBJECTIVE: To non-invasively evaluate differences in oxidative metabolism in individuals with obesity compared to normal weight using the near-infrared spectroscopy and vascular occlusion technique during hyperglycaemia. METHODS: In all, 16 normal-weight individuals (body mass index: 21.3 ± 1.7 kg/m2) and 13 individuals with obesity (body mass index: 34.4 ± 2.0 kg/m2) had five vascular occlusion tests (pre, 30, 60, 90 and 120 min after glucose ingestion). Oxygen utilization was estimated from the area under the curve of the deoxyhemoglobin [HHb] signal during occlusion. Muscle reperfusion was derived from the area above the curve after cuff release. RESULTS: The deoxyhemoglobin area under the curve during occlusion of the normal-weight individuals increased from 15,732 ± 2344 (% . s) at pre to 18,930 ± 3226 (% . s) ( p < 0.05) at 90 min after glucose ingestion. The deoxyhemoglobin area under the curve during occlusion decreased significantly from 14,695 ± 3341 (% . s) at pre to 11,273 ± 1825 (% . s) ( p < 0.05) and 11,360 ± 1750 (% . s) ( p < 0.05) at 30 and 60 min, respectively, after glucose ingestion. The area above the curve of deoxyhemoglobin during reperfusion decreased significantly from 6450 ± 765 (% . s) at pre to 4830 ± 963 (% . s) ( p < 0.05) at 60 min and to 4210 ± 595 (% . s) ( p < 0.01) at 90 min in normal-weight individuals after glucose ingestion, with no changes observed in individuals with obesity. CONCLUSION: This study confirmed in vivo and non-invasively the metabolic inflexibility of skeletal muscle in individuals with obesity during hyperglycaemia.

Changes in vascular responsiveness during a hyperglycemia challenge measured by near-infrared spectroscopy vascular occlusion test.

BACKGROUND: Postprandial hyperglycemia is associated with impaired vascular responsiveness. Recent studies have established the use of a near-infrared spectroscopy (NIRS)-derived approach, combined with a vascular occlusion test (VOT), to examine vascular responsiveness within the microvasculature in normoglycemia. The aim of this study was to examine whether this NIRS-VOT technique could detect differences in vascular responsiveness following a hyperglycemic challenge. METHODS AND RESULTS: Fourteen young healthy individuals participated in the study. Participants underwent five vascular occlusion tests (pre, 30, 60, 90 and 120min after glucose ingestion). Vascular responsiveness was determined by the slope 2 of oxygen saturation (Slope 2 StO2) and the area under the curve of oxygen saturation (StO2AUC) signal. All individuals had a significant increase in blood glucose concentration after 30min (p<0.001), 60min (p<0.001) and 90min (p<0.01) after glucose ingestion. The Slope 2 StO2 increased at 90min (p<0.01) after glucose ingestion. Conversely, The StO2AUC was significantly decreased 90min following the glucose challenge (p<0.01). A negative correlation was observed between average StO2AUC and average Slope 2 StO2 (r=-0.995; p<0.05). CONCLUSION: This study showed that the NIRS-VOT technique is capable of detecting differential changes in vascular responsiveness to a hyperglycemic challenge, as indicated by a steeper Slope 2 StO2 and decreased StO2AUC following 90min of an oral glucose challenge.