ABSTRACT
BACKGROUND: While 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. AIM: To 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). METHODS: Nine 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. RESULTS: No 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. CONCLUSION: The 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.
ABSTRACT
With the objective of analyzing the blood glucose responses during and after exercise performed at 90 and 110% of anaerobic threshold (AT), 10 type-2 diabetes patients (56.9±11.2years; 80.3±14.4kg) performed an incremental test (IT)on a cycle ergometer. After an initial IT to identify AT, the volunteers participated in three experimental sessions on three different days: 20 minutesÆ of cycling at either 90 or 110% of AT, and a control session (CON). Blood glucose was measured at rest, and at the 10th and 20th minutes of exercise or control condition, as well as every 15 minutes during a 2-hour postexercise recovery period (Rec). One-way ANOVA did not detect signifi cant differences in blood glucose levels between the sessions at 90 and 110% of AT. Compared to CON, a significant decrease was observed at the 20th minute of exercise, and at the 15th and 60th minutes of Rec from the 90% AT session. Significant reductions were also observed at the 10th and 20th minutes of exercise and at the 15th, 30th, 45th, 60th and 90th minutes of Rec from the session at 110% AT. Exercise performed at the higher intensity (110% AT) resulted in a tendency of a more pronounced and prolonged hypoglycemic effect during and after exercise, and may be an alternative intensity for glycemic control in type 2 diabetics who do not havecardiovascular complications or other contraindications to exercising at intensities above the AT...
Com o propósito de analisar a resposta da glicose sanguínea durante e após exercício a 90 e 110% do limiaranaeróbio (LA), 10 voluntários diabéticos tipo 2 (56,9 ± 11,2 anos; 80,3 ± 14,4 kg), realizaram um teste incremental (TI) em cicloergômetro. Após a realização do TI para identificação do LA, os voluntários realizaram 3 sessões experimentais em dias distintos: 20 minutos em bicicleta ergométrica a 90 e 110% LA e uma sessão controle (CON). A glicemia foi mensurada no repouso, aos 10 e 20 min de exercício ou na situação controle, bem como a cada 15 minutos durante 2 horas do período de recuperação pós-exercício (Rec) e CON. ANOVA não identifi cou diferenças significantes nas concentrações de glicose sanguínea durante e após as sessões de 90 e 110% LA. Comparado ao controle, redução significativa da glicemia foiobservada aos 20 min de exercício (-41 + 15 mg.dl-1), aos 15 min (-48 + 21 mg.dl-1) e 60 min da Rec pós sessão a 90% LA, sendo também observada diminuição significativa da glicemia aos 10 e 20 min do exercício e aos 15, 30, 45, 60 e 90 min da Rec após sessão de 110% LA. O exercício de maior intensidade (110% LA) resultou em tendência de maior e mais duradouro efeito hipoglicemiante e pode ser uma alternativa para melhor controle da glicose sanguínea em diabéticos tipo 2que não possuam problemas cardiovasculares ou outras complicações e restrições ao exercício realizado acima do LA...
