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Lactate Threshold (D-Max Method) and Maximal Lactate Steady State in Cyclists

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Czuba M., Zając A., Cholewa J., Poprzęcki S., Waśkiewicz Z., Mikołajec K.

Journal of Human Kinetics

2009

vol. 21

49-56

The Maximal Lactate Steady State (MLSS) is defined as the highest workload that can be maintained over time where there is a balance between lactate production and lactate clearance. Therefore, determination of this workload is very importance for diagnosis of aerobic capacity and training program design.The main objective of this study was to evaluate the validity of lactate threshold values determined by the D-max method as related to MLSS in cyclists. The research material included 10 female (body height 167±5.7 cm; body mass 56±4.8 kg; percent body fat 12.3±2.1) and 10 male well-trained cyclists (body height 183.5±4.4 cm; body mass 73.2±4.1 kg; percent body fat 7.9±2.6). The research had two distinct phases, separated by one day of active recovery. During the first phase, progressive tests were carried out to determine lactate threshold and maximal oxygen uptake in each subject. During the second phase, each athlete performed a series of 30-min ergocycle tests, with a fixed workload to establish maximal lactate steady state.Results showed no significant differences between lactate threshold workload (WRLT), determined by the D-max method, and maximal lactate steady state workload (WRMLSS) in female and male cyclists, expressed in absolute and relative values. Differences between male and female cyclists in absolute and relative values of WRLT, WRMLSS, and WRmax were significant (p<0.05), but in relative values there was a tendency for decreased differences between groups. The oxygen uptake at the lactate threshold and MLSS were significantly (p<0.05) different. Also, a significant (p<0.05) difference was observed in values of heart rate and lactate concentration at the lactate threshold and MLSS. The analysis of changes in lactate concentration, heart rate and oxygen uptake between the 10th and 30th minutes of MLSS, indicates that there was a significant (p<0.05) increase in these values in male and female cyclists. The strong correlation (r=0.97; p<0.05) between WRLT and WRMLSS was found. Also, a significant correlation between (r=0.96; p<0.05) WRMLSS and peak workload during the incremental test (WRmax) (r=0.96; p<0.05) was also observed.

Effects of Growth Hormone Therapy and Physical Exercise on Anaerobic and Aerobic Power, Body Composition, Lipoprotein Profile in Middle Aged Men

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Zajâc A., Czuba M., Poprzecki S., Waśkiewicz Z., Cholewa J., Pilch J., Chycki J.

Journal of Human Kinetics

2010

vol. 25

67-76

Recently growth hormone therapy has been used as an age delaying drug in middle aged men and women as well as in the elderly. Positive effects have been shown in regards to body mass and body composition changes, fat metabolism, bone mineral density and muscle strength. Exercise is a potent physiological stimulus for growth hormone secretion and both aerobic and resistance exercise results in significant, acute serum increases in GH concentration. It is unclear however whether a combination of exercise and hGH therapy further increases physical performance in adults and increases changes in body composition and biochemical variables related to health. For this purpose a group of 15 middle aged men (45,7±5,8 years, 93,2±16,3kg and 183,3±4cm), slightly overweight were randomly divided into an experimental and control groups. Both groups exercised for 3 month, performing 2 aerobic sessions per week and 2 resistance workouts, increasing training loads every two weeks. The experimental group received additionally hGH subcutaneous injections beginning with 0,2 IU daily for the first month and then increasing it to 0,4 and 0,6 IU in successive month. VO2max was evaluated during a progressive ergocycle test to volitional exhaustion, while anaerobic power and capacity were measured during the 30s Wingate test. Additionally body mass and body composition were evaluated as well as the lipoprotein profile and the concentration of chosen anabolic hormones. The results indicate a significant rise in resting concentrations of GH and IGF-1 after the replacement therapy but no additional benefits in regards to aerobic fitness and fat metabolism in comparison to exercise only. A more profound effect was observed in case of anaerobic performance, thus it was concluded that even small doses of hGH stimulated additional protein synthesis following resistance exercise what allowed for significant increases in FFM, anaerobic power (W/kg) and capacity (J/kg) as evaluated obtained during the Wingate test. It was concluded that for a more significant effect of hGH therapy in regards to physical performance greater doses of this hormone have to be used, along with an intensive exercise program.

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2 Journal of Human Kinetics

1 2010

1 2009

2 Cholewa J.

2 Czuba M.

2 Waśkiewicz Z.

1 Chycki J.

1 Mikołajec K.

1 Pilch J.

1 Poprzecki S.

1 Poprzęcki S.

1 Zajâc A.

1 Zając A.

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Lactate Threshold (D-Max Method) and Maximal Lactate Steady State in Cyclists

Effects of Growth Hormone Therapy and Physical Exercise on Anaerobic and Aerobic Power, Body Composition, Lipoprotein Profile in Middle Aged Men