Threshold for muscle lactate accumulation during progressive exercise.

Human Performance Laboratory, Ball State University, Muncie, Indiana 47306.
Journal of Applied Physiology (Impact Factor: 3.43). 07/1989; 66(6):2710-6.
Source: PubMed

ABSTRACT The purpose of this study was to investigate the relationship between muscle and blood lactate concentrations during progressive exercise. Seven endurance-trained male college students performed three incremental bicycle ergometer exercise tests. The first two tests (tests I and II) were identical and consisted of 3-min stage durations with 2-min rest intervals and increased by 50-W increments until exhaustion. During these tests, blood was sampled from a hyperemized earlobe for lactate and pH measurement (and from an antecubital vein during test I), and the exercise intensities corresponding to the lactate threshold (LT), individual anaerobic threshold (IAT), and onset of blood lactate accumulation (OBLA) were determined. The test III was performed at predetermined work loads (50 W below OBLA, at OBLA, and 50 W above OBLA), with the same stage and rest interval durations of tests I and II. Muscle biopsies for lactate and pH determination were taken at rest and immediately after the completion of the three exercise intensities. Blood samples were drawn simultaneously with each biopsy. Muscle lactate concentrations increased abruptly at exercise intensities greater than the "below-OBLA" stage [50.5% maximal O2 uptake (VO2 max)] and resembled a threshold. An increase in blood lactate and [H+] also occurred at the below-OBLA stage; however, no significant change in muscle [H+] was observed. Muscle lactate concentrations were highly correlated to blood lactate (r = 0.91), and muscle-to-blood lactate ratios at below-OBLA, at-OBLA, and above-OBLA stages were 0.74, 0.63, 0.96, and 0.95, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

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    ABSTRACT: Aim; The aim of the study is to research the effect of the hot and cold water applications done after the fatigue that occurs in athletes during the aerobic and anaerobic exercises on the recovery process. Materials and Methods; 25 active athletes voluntarily attended the study. The subjects with 170-180 pulse/min pulse pedalled for 9 minutes in which intensity was increased at 3-minute intervals on 170 Ergometric Bicycle in the exercise applied. The blood lactate measurements of the athletes were determined by the Lactate Scout device applied before and after exercise. The hot and cold applications of the subjects; the 1st test was applied by staying in the cold pool (10°C -15 °C) passively for 10 minutes soon after the exercise. The 2nd test was applied 1 week later by giving hot water application (37°C -40 °C) to the athletes for 10 minutes after the same exercise was done. Oneway Anova at the level of α=0.05 test was applied in the analysis of data and Tukey test was done between the groups. Results; The age (year) of the athletes: 22,1 ±2,35, height (cm): 182,00 ± 10,00i body weight (kg): 80,76 ± 11,39. The heart rate of the athletes (HR) were determined; at rested position: 59,70±2,65 pulse/min., post-exercise: 174,40±6,60 pulse/min., post-warm pool: 91,56 ±5,19 pulse/min., post-cold pool: 90,36±6,55 pulse/min. The Blood Lactate (LA) measurements of the athletes were determined; at rested position: 2,72±0,49 mmol, post-exercise: 5,21±075 mmol, post-warm pool: 4,63 ±0,81 mmol, post-cold pool: 4,61± 0,73 mmol. The blood LA measurements of the athletes were determined by drawing blood from the finger tips. Discussion and Result; The results of the test showed that there was a significant difference between the heart rate (F=5127, 85) and blood lactate (F=160,74) of the subjects at rested position, post-exercise, post-warm pool and post-cold pool applications. However, it was seen in the TUKEY test that there was not any difference in the heart rate and blood lactate values of the subjects after the warm pool and cold pool applications.
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    ABSTRACT: Studies on the assessment of heart rate variability threshold (HRVT) during walking are scarce. We determined the reliability and validity of HRVT assessment during the incremental shuttle walk test (ISWT) in healthy subjects. Thirty-one participants aged 57 ± 9 years (17 females) performed 3 ISWTs. During the 1st and 2nd ISWTs, instantaneous heart rate variability was calculated every 30 s and HRVT was measured. Walking velocity at HRVT in these tests (WV-HRVT1 and WV-HRVT2) was registered. During the 3rd ISWT, physiological responses were assessed. The ventilatory equivalents were used to determine ventilatory threshold (VT) and the WV at VT (WV-VT) was recorded. The difference between WV-HRVT1 and WV-HRVT2 was not statistically significant (median and interquartile range = 4.8; 4.8 to 5.4 vs 4.8; 4.2 to 5.4 km/h); the correlation between WV-HRVT1 and WV-HRVT2 was significant (r = 0.84); the intraclass correlation coefficient was high (0.92; 0.82 to 0.96), and the agreement was acceptable (-0.08 km/h; -0.92 to 0.87). The difference between WV-VT and WV-HRVT2 was not statistically significant (4.8; 4.8 to 5.4 vs 4.8; 4.2 to 5.4 km/h) and the agreement was acceptable (0.04 km/h; -1.28 to 1.36). HRVT assessment during walking is a reliable measure and permits the estimation of VT in adults. We suggest the use of the ISWT for the assessment of exercise capacity in middle-aged and older adults.
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