Herbert Gustavo Simões

Blood glucose responses in humans mirror lactate responses for individual anaerobic threshold and for lactate minimum in track tests

Abstract The equilibrium point between blood lactate production and removal (La−min) and the individual anaerobic threshold (IAT) protocols have been used to evaluate exercise. During progressive exercise, blood lactate [La−]b, catecholamine and cortisol concentrations, show exponential increases at upper anaerobic threshold intensities. Since these hormones enhance blood glucose concentrations [Glc]b, this study investigated the [Glc] and [La−]b responses during incremental tests and the possibility of considering the individual glucose threshold (IGT) and glucose minimum (Glcmin) in addition to IAT and La−min in evaluating exercise. A group of 15 male endurance runners ran in four tests on the track 3000 m run (v3km); IAT and IGT – 8 × 800 m runs at velocities between 84% and 102% of v3km; La−min and Glcmin– after lactic acidosis induced by a 500-m sprint, the subjects ran 6 × 800 m at intensities between 87% and 97% of v3km; endurance test (ET) – 30 min at the velocity of IAT. Capillary blood (25 μl) was collected for [La−]b and [Glc]b measurements. The IAT and IGT were determined by [La−]b and [Glc]b kinetics during the second test. The La−min and Glcmin were determined considering the lowest [La−] and [Glc]b during the third test. No differences were observed (P < 0.05) and high correlations were obtained between the velocities at IAT [283 (SD 19) and IGT 281 (SD 21) m. · min−1; r = 0.096; P < 0.001] and between La−min [285 (SD 21)] and Glcmin [287 (SD 20) m. · min−1r = 0.77; P < 0.05]. During ET, the [La−]b reached 5.0  (SD 1.1) and 5.3 (SD 1.0) mmol · l−1 at 20 and 30 min, respectively (P > 0.05). We concluded that for these subjects it was possible to evaluate the aerobic capacity by IGT and Glcmin as well as by IAT and La−min.

Noninvasive method to estimate anaerobic threshold in individuals with type 2 diabetes

BackgroundWhile several studies have identified the anaerobic threshold (AT) through the responses of blood lactate, ventilation and blood glucose others have suggested the response of the heart rate variability (HRV) as a method to identify the AT in young healthy individuals. However, the validity of HRV in estimating the lactate threshold (LT) and ventilatory threshold (VT) for individuals with type 2 diabetes (T2D) has not been investigated yet.AimTo analyze the possibility of identifying the heart rate variability threshold (HRVT) by considering the responses of parasympathetic indicators during incremental exercise test in type 2 diabetics subjects (T2D) and non diabetics individuals (ND).MethodsNine T2D (55.6 ± 5.7 years, 83.4 ± 26.6 kg, 30.9 ± 5.2 kg.m2(-1)) and ten ND (50.8 ± 5.1 years, 76.2 ± 14.3 kg, 26.5 ± 3.8 kg.m2(-1)) underwent to an incremental exercise test (IT) on a cycle ergometer. Heart rate (HR), rate of perceived exertion (RPE), blood lactate and expired gas concentrations were measured at the end of each stage. HRVT was identified through the responses of root mean square successive difference between adjacent R-R intervals (RMSSD) and standard deviation of instantaneous beat-to-beat R-R interval variability (SD1) by considering the last 60 s of each incremental stage, and were known as HRVT by RMSSD and SD1 (HRVT-RMSSD and HRVT-SD1), respectively.ResultsNo differences were observed within groups for the exercise intensities corresponding to LT, VT, HRVT-RMSSD and HHVT-SD1. Furthermore, a strong relationship were verified among the studied parameters both for T2D (r = 0.68 to 0.87) and ND (r = 0.91 to 0.98) and the Bland & Altman technique confirmed the agreement among them.ConclusionThe HRVT identification by the proposed autonomic indicators (SD1 and RMSSD) were demonstrated to be valid to estimate the LT and VT for both T2D and ND.

Hypotensive effects of exercise performed around anaerobic threshold in type 2 diabetic patients

AIM To verify the occurrence of post-exercise hypotension (PEH) in type 2 diabetics (DM(2)) and the effects of exercise intensity on post-exercise blood pressure (BP). METHODS Eleven men and women with DM(2) (58.5+/-10.2 years; 160+/-0.1cm; 80.6+/-13.5kg; 31.2+/-3.8kg/m(2), 19+/-3.2mLkgmin(-1) of VO(2max), 155.0+/-39.2mgdL(-1) of fasting blood glucose and 126+/-10/75+/-7mmHg of resting BP) performed an incremental test (IT) for cardiovascular evaluation and anaerobic threshold (AT) determination. Then, participants randomly underwent 2 exercise sessions (90% and 110% AT) and a control session (CON). In all sessions, BP was measured at resting, during 20min of exercise/control and at each 15min through 120min of post-exercise recovery (R15-R120). RESULTS The mean results of systolic BP (SBP)/diastolic BP (DBP) over the 120min of recovery were 125+/-16/76+/-7mmHg, 122+/-13/75+/-6mmHg and 129+/-16/78+/-7mmHg, respectively for 90%, 110% and CON. Significant reductions of SBP occurred after 90% (R15-R45) and 110% (R15-R90), while only after 110% there were reductions of DBP (R15, R45) and MAP (R15, R45, R75, R90, R105). CONCLUSIONS Both exercise intensities evoked reductions in SBP while DBP and MAP were reduced only after 110%. Despite the higher intensity exercise to be more effective in promoting BP reductions, we suggest caution while prescribing exercise for DM(2).

Predicting insulin resistance in children: anthropometric and metabolic indicators

OBJECTIVE To predict insulin resistance in children based on anthropometric and metabolic indicators by analyzing the sensitivity and specificity of different cutoff points. METHODS A cross-sectional study was carried out of 109 children aged 7 to 11 years, 55 of whom were obese, 23 overweight and 31 well-nourished, classified by body mass index (BMI) for age. Measurements were taken to determine BMI, waist and hips circumferences, waist circumference/hip circumference ratio, conicity index and body fat percentage (dual emission X-ray absorptiometry). Fasting blood samples were taken to measure triglyceridemia, glycemia and insulinemia. Insulin resistance was evaluated by the glycemic homeostasis method, taking the 90th percentile as the cutoff point. Receiver operating characteristic curves were analyzed to a 95% confidence interval in order to identify predictors of glycemic homeostasis, and sensitivity and specificity were then calculated. RESULTS After analysis of the area under the receiver operating characteristic curve (confidence interval), indicators that demonstrated the power to predict insulin resistance were, in the following order: insulinemia = 0.99 (0.99-1.00), 18.7 microU mL(-1); body fat percentage = 0.88 (0.81-0.95), 41.3%; BMI = 0.90 (0.83-0.97), 23.69 kg m(2-(1)); waist circumference= 0.88 (0.79-0.96), 78.0 cm; glycemia = 0.71 (0.54-0.88), 88.0 mg dL(-1); triglyceridemia = 0.78 (0.66-0.90), 116.0 mg dL(-1) and conicity index = 0.69 (0.50-0.87), 1.23 for the whole sample; and were: insulinemia = 0.99 (0.98-1.00), 19.54 microU mL(-1); body fat percentage = 0.76 (0.64-0.89), 42.2%; BMI = 0.78 (0.64-0.92), 24.53 kg m(2-(1)); waist circumference = 0.77 (0.61-0.92), 79.0 cm and triglyceridemia = 0.72 (0.56-0.87), 127.0 mg dL(-1), for the obese subgroup. CONCLUSIONS Anthropometric and metabolic indicators appear to offer good predictive power for insulin resistance in children between 7 and 11 years old, employing the cutoff points with the best balance between sensitivity and specificity of the predictive technique.

Postresistance exercise blood pressure reduction is influenced by exercise intensity in type-2 diabetic and nondiabetic individuals.

Simões, GC, Moreira, SR, Kushinick, MR and Simões, HG, and Campbell CSG. Postresistance exercise blood pressure reduction is influenced by exercise intensity in type-2 diabetic and nondiabetic individuals. J Strength Cond Res 24(5): 1277-1284, 2010-This study analyzed the postexercise blood pressure (BP) after resistance exercise (RE) on middle-aged type-2 diabetic (T2DM, n = 10, 46.6 ± 13.1 years) and nondiabetic subjects (NDM, n = 10, 52.0 ± 13.2 years). Participants performed (a) 1 repetition maximum (1RM) strength test; (b) 3 laps in an RE circuit of 6 exercises (16 repetitions at 43% 1RM); (c) 3 laps in an RE circuit (30 repetitions at 23% 1RM); and (d) a control session. The blood lactate concentration ([lac]) (YSI 2700S) and BP (Microlife BP3AC1-1) were measured pre-exercise, after exercise, and at each 15 minutes during the 120 minutes of recovery. Analysis of variance with Bonferroni as a post hoc evidenced that the 43% 1RM session elicited the highest [lac] response for both NDM (7.8 ± 1.8 vs. 6.4 ± 1.8 mmol·L−1; p < 0.05) and T2DM (7.0 ± 1.4 vs. 5.6 ± 1.6 mmol·L−1; p < 0.05). Also, the 43% 1RM session promoted a significant postexercise hypotension (PEH) of systolic blood pressure (SBP) and mean arterial pressure (MAP), whereas the 23% 1RM did not. The highest BP reductions for T2DM and NDM after 43% 1RM were, respectively, 9.5 ± 11.1and 11.0 ± 7.1 mmHg for SBP and 6.4 ± 7.8 and 7.7 ± 7.9 mmHg for the MAP (p ≤ 0.05). The PEH of SBP lasted longer (120 minutes) for NDM than for T2DM (90 minutes). The PEH may be associated with [lac] elevation, and the lower hypotensive effect presented by T2DM may be related to endothelial dysfunction usually observed in diabetic individuals. In conclusion, the RE of higher intensity, performed in ∼25-minute duration, was more efficient at promoting PEH which, in turn, suggests its use on BP control for middle-aged T2DM and NDM subjects with characteristics similar to those of our participants.

Methods to identify the lactate and glucose thresholds during resistance exercise for individuals with type 2 diabetes.

Moreira, SR, Arsa, G, Oliveira, HB, Lima, LCJ, Campbell, CSG, Simões, HG. Methods to identify the lactate and glucose thresholds during resistance exercise for individuals with type 2 diabetes. J Strength Cond Res 22: 1108-1115, 2008-The purpose of this study was to compare different methods to identify the lactate threshold (LT) and glucose threshold (GT) on resistance exercise for individuals with type 2 diabetes. Nine men with type 2 diabetes (47.2 ± 12.4 years, 87.6 ± 20.0 kg, 174.9 ± 5.9 cm, and 22.4 ± 7.2% body fat) performed incremental tests (ITs) on the leg press (LP) and bench press (BP) at relative intensities of 10, 20, 25, 30, 35, 40, 50, 60, 70, 80, and 90% of one-repetition maximum (1RM) at each 1-minute stage. During the 2-minute interval between stages, 25 μl of capillary blood were collected from the earlobe for blood lactate [Lac] and blood glucose [Gluc] analysis (YSI 2700S). The LT in the LP and BP was identified at IT by the inflexion in [Lac] response as well as by an equation originated from a polynomial adjustment (LTp) of the [Lac]/% 1RM ratio responses. The lowest [Gluc] during the IT identified the GT. The analysis of variance did not show differences among the 1RM at the thresholds identified by different methods in the LP (LTLP = 31.0% ± 5.3% 1RM; GTLP = 32.1% ± 6.1% 1RM; LTpLP = 36.7% ± 5.6% 1RM; p > 0.05) and BP (LTBP = 29.9% ± 8.5% 1RM; GTBP = 32.1% ± 8.5% 1RM; LTpBP = 31.8% ± 6.7% 1RM; p > 0.05). It was concluded that it was possible to identify the LT and GT in resistance exercise by different methods for individuals with type 2 diabetes with no differences between them. The intensities (kg) corresponding to these thresholds were between 46% and 60% of the body weight on the LP and between 18% and 26% of the body weight on the BP, in which the exercise prescription would be done to this intensity in 3 sets of 20 to 30 repetitions each and 1 minute of rest while alternating the muscle groups for blood glucose control for individuals with characteristics similar to the participants.

Acute exercise performed close to the anaerobic threshold improves cognitive performance in elderly females

The objective of the present study was to compare the effect of acute exercise performed at different intensities in relation to the anaerobic threshold (AT) on abilities requiring control of executive functions or alertness in physically active elderly females. Forty-eight physically active elderly females (63.8 +/- 4.6 years old) were assigned to one of four groups by drawing lots: control group without exercise or trial groups with exercise performed at 60, 90, or 110% of AT (watts) and submitted to 5 cognitive tests before and after exercise. Following cognitive pretesting, an incremental cycle ergometer test was conducted to determine AT using a fixed blood lactate concentration of 3.5 mmol/L as cutoff. Acute exercise executed at 90% of AT resulted in significant (P < 0.05, ANOVA) improvement in the performance of executive functions when compared to control in 3 of 5 tests (verbal fluency, Tower of Hanoi test (number of movements), and Trail Making test B). Exercising at 60% of AT did not improve results of any tests for executive functions, whereas exercise executed at 110% of AT only improved the performance in one of these tests (verbal fluency) compared to control. Women from all trial groups exhibited a remarkable reduction in the Simple Response Time (alertness) test (P = 0.001). Thus, physical exercise performed close to AT is more effective to improve cognitive processing of older women even if conducted acutely, and using a customized exercise prescription based on the anaerobic threshold should optimize the beneficial effects.

The higher exercise intensity and the presence of allele I of ACE gene elicit a higher post-exercise blood pressure reduction and nitric oxide release in elderly women: an experimental study

BackgroundThe absence of the I allele of the angiotensin converting enzyme (ACE) gene has been associated with higher levels of circulating ACE, lower nitric oxide (NO) release and hypertension. The purposes of this study were to analyze the post-exercise salivary nitrite (NO2-) and blood pressure (BP) responses to different exercise intensities in elderly women divided according to their ACE genotype.MethodsParticipants (n = 30; II/ID = 20 and DD = 10) underwent three experimental sessions: incremental test - IT (15 watts workload increase/3 min) until exhaustion; 20 min exercise 90% anaerobic threshold (90% AT); and 20 min control session without exercise. Volunteers had their BP and NO2- measured before and after experimental sessions.ResultsDespite both intensities showed protective effect on preventing the increase of BP during post-exercise recovery compared to control, post-exercise hypotension and increased NO2- release was observed only for carriers of the I allele (p < 0.05).ConclusionGenotypes of the ACE gene may exert a role in post-exercise NO release and BP response.

Maximal lactate steady-state prediction through quadratic modeling of selected stages of the lactate minimum test.

Pardono, E, da Costa Sotero, R, Hitane, W, Mota, MR, Campbell, CSG, Nakamura, FY, and Simões, HG. Maximal lactate steady-state prediction through quadratic modeling of selected stages of the lactate minimum test. J Strength Cond Res 22: 1073-1080, 2008-In this study, we compared the maximal lactate steady state (MLSS) with lactate minimal (LM) intensities determined visually and through a quadratic polynomial function of selected stages of LM test. Eleven male recreational cyclists (27.7 ± 4.5 years, 175.7 ± 5.6 cm, 69.5 ± 10.8 kg, and 12.0 ± 5.5% body fat) performed one LM test under previous induction of hyperlactaemia with an initial intensity of 75 W with 30-W increments every 3 minutes with blood lactate concentration (HLa) and rating of perceived exertion (RPE) measurements. The LM intensity was determined visually (VLM) and by modeling the lactate response through polynomial function by using: 1) all stages (LMP); 2) the first stage, the stage corresponding to RPE-13 and the last stage/exhaustion (LMP3max); 3) the three lowest lactate concentration stages (LMP3adj); and 4) the initial, RPE-13, and RPE-16 stages (LMP3sub). The MLSS was determined as the highest intensity at a variation not greater than 0.05 mmol·l-1·min-1 of HLa during the last 20 minutes of a 30-minute exercise session. The MLSS (204.0 ± 16.0 W), VLM (198.6 ± 15.2 W), LMP3adj (190.4 ± 12.9 W), and LMP3sub (192.1 ± 27.2 W) were not different, well correlated, and in agreement to each other. In conclusion, the polynomial modeling of HLa response to three submaximal stages produced exercise intensities that did not differ from MLSS.

Lactate Threshold Prediction by Blood Glucose and Rating of Perceived Exertion in People with Type 2 Diabetes

The validity of rating of perceived exertion (RPE) in predicting lactate threshold during an incremental test was analyzed in 15 men with type 2 diabetes (M age = 53.4 yr., SD = 12.9). Blood glucose, lactate, and minute ventilation (VE)/VO2 responses identified the lactate, ventilatory, and glucose thresholds. Workloads (W) corresponding to RPEs 12, 13, 14, and 15 were determined. Second-order polynomials fit to VE/W and [lac]/W ratios corresponding to RPEs of 9–10, 12–13, and 16–17 also identified workloads above which there was an overproportional increase in VE and [lac]. These workload breakpoints did not differ, although at RPE 12 underestimated and at RPE 15 overestimated lactate threshold. RPE 13 and 14 and the responses of VE/W and [lac]/W to submaximal exercise accurately predicted lactate threshold.