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.

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).

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

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.min 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.

Blood glucose responses of type-2 diabetics during and after exercise performed at intensities above and below anaerobic threshold

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...

Velocidade crítica como um método não invasivo para estimar a velocidade de lactato mínimo no ciclismo / La velocidad crítica como un método no invasivo para estimar la velocidad de lactato mínimo en el ciclismo / Critical velocity as a noninvasive method to estimate the lactate minimum velocity on cycling

A velocidade de lactato mínimo (VLM) representa o ponto de equilíbrio entre produção e remoção do lactato sanguíneo (lac). Com objetivo de analisar a validade da velocidade crítica (VC) como método não invasivo de estimar a VLM no ciclismo outdoor, 15 ciclistas (67,9 ± 5,7kg; 1,70 ± 0,1m; 26,7 ± 4,2 anos) percorreram as distâncias de 2, 4 e 6km em velódromo no menor tempo possível. A VC foi identificada pelo modelo distância-tempo a partir das combinações de séries preditivas de 2 e 4km (VC2/4), 2 e 6km (VC2/6), 4 e 6km (VC4/6) e 2, 4 e 6km (VC2/4/6). Para identificação da VLM foi realizada uma série de 2km à máxima velocidade, seguida de seis séries incrementais de 2km com 1 minuto de pausa para dosagem de lac. A VLM foi identificada visualmente (VLMv) e aplicando-se função polinomial (VLMp). Não foram observadas diferenças entre VLMv (33,3 ± 2,5km.h¹) e VLMp (33,1 ± 2,6km.h¹). Com exceção da VC4/6 (34,6 ± 3,5km.h¹), os valores de VC2/4 (38,0 ± 2,2km.h¹), VC2/6 (36,1 ± 2,4km.h¹) e VC2/4/6 (36,1 ± 2,5km.h¹) diferiram da VLMp e VLMv. Os autores concluem que, apesar de ser ~1km/h acima da VLM, a VC identificada a partir de séries preditivas de maior duração (4 e 6km - aproximadamente 6 e 10 min) não diferem estatisticamente e apresentam alta correlação e concordância com a VLM. No entanto, é necessário investigar se a VC representa um equilíbrio entre remoção e produção de lac durante exercícios de longa duração no ciclismo outdoor.

The lactate minimum velocity (LMV) represents the equilibrium point between blood lactate (lac) production and removal. With the purpose of analyzing the validity of critical velocity (CV) as a non-invasive method to estimate the LMV on outdoor cycling, 15 cyclists (67.9 ± 5.7 kg; 1.70 ± 0.1 m; 26.7 ± 4.2 years) performed all-out tests on distances of 2, 4 and 6 km on velodrome. The CV was identified by distance-time model from combinations of 2 and 4 km (CV2/4), 2 and 6 km (CV2/6), 4 and 6 km (CV4/6) and 2, 4 and 6 km (CV2/4/6). The LMV was identified during 6 x 2 km incremental bouts after a latic acidosis induced by the all-out 2 km. The lower lac during test identified the LMV visually (LMVv) and by applying a polynomial function (LMVp). No differences were observed between LMVv (33.3 ± 2.5 km.h¹) and LMVp (33.1 ± 2.6 km.h¹). Apart from CV4/6 (34.6 ± 3.5 km.h¹), the values of CV2/4 (38.0 ± 2.2 km.h¹), CV2/6 (36.1 ± 2.4 km.h¹) and CV2/4/6 (36.1 ± 2.5 km.h¹) differed from LMVp and LMVv (P < 0,001). The authors concluded that, besides being ~1 km/h above the LMV, the CV determined through predictive series of longer duration (4 and 6 km approximately 6 and 10 min) did not differ statistically from LMV and presented a high correlation and agreement to each other. However, it is necessary to investigate whether the CV reflects the balance between lac production and removal during long-term exercise on outdoor cycling.

La velocidad de lactato mínimo (VLM) representa el punto de equilibrio entre la producción y la remoción de lactato sanguíneo (lac). Con el objetivo de analizar la validez de la velocidad crítica (VC) como método no invasivo de estimar la VLM en el ciclismo "outdoor", 15 ciclistas (67,9 ± 5,7 kg; 1,70 ± 0,1 m; 26,7 ± 4,2 años) percorrieron distancias de 2, 4 y 6 km en velódromo en el menor tiempo posible. La VC fue identificada por el modelo distancia-tiempo a partir de las combinaciones de series predictivas de 2 y 4 km (VC2/4), 2 y 6 km (VC2/6), 4 y 6 km (VC4/6) y 2, 4 y 6km (VC2/4/6). Para la identificación de VLM fue realizada una serie de 2km a máxima velocidad, seguida de 6 series incrementales de 2km con 1 minuto de pausa para dosaje de lac. La VLM fue identificada visualmente (VLMv) y aplicando función polinomial (VLMp). No se observaron diferencias entre VLMv (33,3 ± 2,5km.h¹) y VLMp (33,1 ± 2,6km.h¹). A excepción de VC4/6 (34,6 ± 3,5km.h¹), los valores de VC2/4 (38,0 ± 2,2km.h¹), VC2/6 (36,1 ± 2,4km.h¹) y VC2/4/6 (36,1 ± 2,5km.h¹) difirieron de VLMp y VLMv. Concluimos que, a pesar de ser ~1km/h por encima de VLM, la VC identificada a partir de series predictivas de mayor duración (4 y 6km - aproximadamente 6 y 10 min) no tienen diferencia estadística y presentan alta correlación y concordancia con VLM. A pesar de esto, es necesario investigar si la VC representa un equilibrio entre remoción y producción de lac durante los ejercicios de larga duración en ciclismo outdoor.