Blood lactate concentration at the maximal lactate steady state is not dependent on endurance capacity in healthy recreationally trained individuals.

The aim of the study was to investigate the independent relationship between maximal lactate steady state (MLSS), blood lactate concentration [La] and exercise performance as reported frequently. Sixty-two subjects with a wide range of endurance performance (MLSS power output 199 ± 55 W; range: 100-302 W) were tested on an electronically braked cycle ergometer. One-min incremental exercise tests were conducted to determine maximal variables as well as the respiratory compensation point (RCP) and the second lactate turn point (LTP2). Several continuous exercise tests were performed to determine the MLSS. Subjects were divided into three clusters of exercise performance. Dietary control was employed throughout all testing. No significant correlation was found between MLSS [La] and power output at MLSS. Additionally, the three clusters of subjects with different endurance performance levels based on power output at MLSS showed no significant difference for MLSS [La]. MLSS [La] was not significantly different between men and women (average of 4.80 ± 1.50 vs. 5.22 ± 1.52 mmol l(-1)). MLSS [La] was significantly related to [La] at RCP, LTP2 and at maximal power. The results of this study support previous findings that MLSS [La] is independent of endurance performance. Additionally, MLSS [La] was not influenced by sex. Correlations found between MLSS [La] and [La] at maximal power and at designated anaerobic thresholds indicate only an association of [La] response during incremental and MLSS exercise when utilizing cycle ergometry.

Sprinting analysis of elite soccer players during European Champions League and UEFA Cup matches.

It has been suggested that assessment of high-intensity activities during a match is a valid measure of physical performance in elite soccer. Recently, sprinting activities have been analysed in more depth. The aim of this study was to develop a detailed analysis of the sprinting activities of different playing positions during European Champions League and UEFA Cup competitions. Altogether, 717 elite outfield soccer players were evaluated throughout 2002-2006 using ProZone® (Leeds, UK). Sprinting (explosive and leading) was analysed for each playing position. To compare positional differences, a Kruskal-Wallis analysis was performed. Differences were found among positions for total number of sprints and total sprint distance covered: wide midfielders > (attackers = wide defenders) > central midfielders > central defenders (P < 0.001), as well as for explosive sprints: (wide midfielders = attackers = wide defenders) > central defenders, wide midfielders > central midfielders > central defenders and attackers = wide defenders = central midfielders (P < 0.001), and leading sprints: wide midfielders > (attackers = wide defenders) > central midfielders > central defenders (P < 0.001). For each group, there were no differences in ratio of explosive to leading sprints. Wide midfielders performed a higher number of sprints in all five distance categories than all other positions. This study showed that sprinting characteristics are influenced by position. Wide midfielders have to complete additional high-intensity activities during training sessions compared with the other positions to achieve the performance level required during the match.

Effect of Strength Training on Glycemic Control and Adiponectin in Diabetic Children.

PURPOSE: This study aimed to examine the effect of isolated supervised progressive resistance training with duration of more than 32 wk on muscle strength, metabolic control and adiponectin. METHOD: Twenty-one children with type 1 diabetes mellitus were separated into an intervention group (IG) (n = 11 age 11.0 ± 0.8) and a control group (CG) (n = 10 age 11.30 ± 0.7) without training to control for the effect of progressive resistance training on muscle strength, hemoglobin (HbA)1C and adiponectin. All parameters were assessed before and after a period of 32 wk. No attempt was made to change diet and the daily behaviors during the study in both groups. RESULTS: After a period of 32 wk, upper and lower limb strength increased significantly (P < 0.05) in the IG, whereas no changes occurred in the CG. In the IG, HbA1C decreased significantly after 32 wk but not after 17 wk (P < 0.00), whereas HbA1C increased in the CG (P < 0.007). Adiponectin increased significantly (P < 0.000) only in the IG. Self-monitored blood glucose levels, measured before and after each session, showed a significant reduction (P < 0.00) of 26.5% ± 4.4% after each session. Effect size (ES) for the strength training on limb strength was medium (d = 0.464 to d = 0.661), the ES for strength training on HbA1C (d = -1.292) and the ES for strength training on adiponectin (d = 1.34) was large. There was no hypoglycemia as the result of training. CONCLUSIONS: An isolated supervised progressive resistance training two times a week in children with type 1 diabetes mellitus must last at least 32 wk to get a significant decrease in blood glucose level HbA1C. In addition, exercise-induced increase in adiponectin improves insulin sensitivity.

Functional performance in community-dwelling and institutionalized elderly women.

OBJECTIVES: Previous reports have underlined the importance of physical activity for physical functioning in older age. As recent results suggest that living in nursing homes is negatively correlated to physical activity level, this survey examined whether muscular power, balance abilities and response times differ between community-dwelling and institutionalized old women. METHODS: A sample of 31 community-dwelling and institutionalized women aged 77-86 years was recruited. Groups did not differ in age, weight, height, or BMI (p > 0.05). Measurements of upper limb power, balance control, and response time were conducted. Upper limb power was tested by dumbbell biceps curl exercise with increasing loads (0.5, 1, 1.5, and 2 kg). Overall daily time expenditure for walking and further physical activities as well as kinds of further activities were examined via questionnaire. RESULTS: The community-dwelling subjects achieved significantly better results in tests of upper limb power and response time (p

Menstrual cycle: no effect on exercise cardiorespiratory variables or blood lactate concentration.

PURPOSE: Numerous investigations have reported changes in metabolic and cardiorespiratory responses associated with the menstrual cycle. We examined whether variables commonly used in exercise testing are influenced by menstrual cycle phases. METHODS: Nineteen eumenorrheic women performed two incremental tests to voluntary exhaustion on a cycle ergometer during two different phases of the menstrual cycle: the follicular phase (FP) and the luteal phase (LP). Our study variables were power output, VO2, HR, VE, RER, ventilatory equivalents of oxygen (VE/VO2) and carbon dioxide (VE/VCO2), and blood lactate concentration (LA) and were measured at rest, at exhaustion, and at different thresholds of aerobic and anaerobic metabolism. The threshold determination consisted of a three-phase model with two lactate turnpoints (LTP1, LTP2) and a three-phase model with two respiratory thresholds: the anaerobic threshold (AT) and the respiratory compensation point (RCP). RESULTS: When comparing power output, VO2, LA, HR, and RER, we found no significant differences between FP and LP at rest, at maximal load, at any selected threshold, or any stage of the incremental tests. We observed higher values for VE/VO2, VE/VCO2, and VE at rest, at exhaustion, and at our AT in LP. CONCLUSION: We did not find performance changes associated with menstrual cycle. Our data do not support findings that the menstrual cycle influences lactate "thresholds" and ventilatory "thresholds." In agreement with other studies, we observed a higher ventilatory drive in the LP compared with the FP of the menstrual cycle.

Respiratory gas exchange and lactate measures during competitive orienteering.

PURPOSE: In the past, orienteering sports analyses were based on heart rate (HR) and lactate (LA) measures. This study assessed additional respiratory gas exchange measures (RGEM) to provide further information regarding the physiological requirements of orienteering competitions (OTC). METHODS: Eleven elite male athletes performed simulated OTC. RGEM were performed using a portable system. LA was determined after each section (total of six) of OTC. Athletes were also subjected to treadmill testing (TT). RESULTS: Average values for the entire OTC were [OV0312]O(2OTC): 56.4 +/- 4.5 mL.kg-1.min-1 (83.0 +/- 3.8% of [OV0312]O(2max) of TT), HR(OTC): 172 +/- 11 bpm, and LA(OTC): 5.16 +/- 1.5 mmol.L-1. The highest measured [OV0312]O(2OTC) of an athlete in this study was 64.4 +/- 2.9 mL.kg-1.min-1. [OV0312]O(2OTC) was 94.6 +/- 5.2% of [OV0312]O(2IAT) (IAT= individual anaerobic threshold), HR(OTC) was 98.0 +/- 2.9% of HR(IAT), respiratory exchange ratio was 97 +/- 3.8% and LA(OTC) was 143.9 +/- 24.2% of LA(IAT). In contrast to [OV0312]O(2) and LA, average HR were similar in all sections of OTC despite topographical differences of the course. No correlations were found between running time of OTC and variables of endurance performance. Running time correlated with running distance (P < 0.001; r = 0.83) and running speed (r = 0.98; P < 0.001). CONCLUSION: 1) Energy requirements during OTC were derived predominately via aerobic metabolism. 2) The highest [OV0312]O(2OTC) value of 64.4 mL.kg-1.min-1 may be regarded as the reference for intensities of OTC. 3) During OTC, most athletes avoid high-intensity periods of long duration. 4) Performance in OTC was essentially influenced by technical abilities. 5) Using only LA for evaluation may lead to overestimation of energy demands during OTC. 6) HR measures were not sufficiently sensitive to ascertain energy requirements of the OTC. Therefore, RGEM provided additional information regarding energy expenditure of OTC compared with LA and HR measures alone.

Time kinetics of acute changes in muscle architecture in response to resistance exercise.

OBJECTIVES: The study aimed to assess acute changes in muscle architecture and its recovery after exhaustive exercise. We hypothesised that repetitive leg press exercise would decrease vastus lateralis fascicle length, while increasing both muscle thickness and pennation angles. By investigating the time kinetics of recovery of these parameters, we wished to gain insight into the mechanisms responsible for muscle architectural changes during exercise. DESIGN: Muscle architecture was assessed in 41 male volunteers (25.2±3.7 yrs; 1.78±0.06 m; 76.4±11.7 kg) before and directly after, as well as 5, 10, 15, and 30 min after induction of fatigue by leg press exercise. METHOD: Vastus lateralis muscle thickness, pennation angles and fascicle lengths were measured at rest by ultrasonography. Muscular fatigue was induced by an exhaustive series of maximum power, single leg press repetitions. RESULTS: Following leg press exercise vastus lateralis muscle thickness and pennation angles were increased by approximately 7 and 10%, whereas fascicle lengths decreased by 2%. Different recovery times (muscle thickness: 30 min; pennation angles: 15 min; fascicle lengths: 5 min) were observed. CONCLUSIONS: The differential time courses of recovery suggest that changes in muscle thickness, pennation angles, and fascicle lengths are driven by different exercise-related stimuli. Increased muscle perfusion and tendon creep are likely candidates accounting for short-term changes in muscle architecture.

Changes in blood lactate and respiratory gas exchange measures in sports with discontinuous load profiles.

This study compares two different sport events (orienteering = OTC; tennis = TEC) with discontinuous load profiles and different activity/recovery patterns by means of blood lactate (LA), heart rate (HR), and respiratory gas exchange measures (RGME) determined via a portable respiratory system. During the TEC, 20 tennis-ranked male subjects [age: 26.0 (3.7) years; height: 181.0 (5.7) cm; weight: 73.2 (6.8) kg; maximal oxygen consumption (VO(2)max): 57.3 (5.1) ml.kg(-1).min(-1)] played ten matches of 50 min. During the OTC, 11 male members of the Austrian National Team [age: 23.5 (3.9) years; height: 183.6 (6.8) cm; weight: 72.4 (3.9) kg; VO(2)max: 67.9 (3.8) ml.kg(-1).min(-1)] performed a simulated OTC (six sections; average length: 10.090 m). In both studies data from the maximal treadmill tests (TT) were used as reference values for the comparison of energy expenditure of OTC and TEC. During TEC, the average VO(2) was considerably lower [29.1 (5.6) ml(.)kg(-1.)min(-1)] or 51.1 (10.9)% of VO(2)max and 64.8.0 (13.3)% of VO(2) determined at the individual anaerobic threshold (IAT) on the TT. The short high-intensity periods (activity/recovery = 1/6) did not result in higher LA levels [average LA of games: 2.07 (0.9) mmol.l(-1)]. The highest average VO(2 )value for a whole game was 47.8 ml.kg(-1.)min(-1) and may provide a reference for energy demands required to sustain high-intensity periods of tennis predominantly via aerobic mechanism of energy delivery. During OTC, we found an average VO(2) of 56.4 (4.5) ml.kg(-1).min(-1) or 83.0 (3.8)% of VO(2)max and 94.6 (5.2)% of VO(2) at IAT. In contrast to TEC, LA were relatively high [5.16 (1.5) mmol.l(-1)) although the average VO(2) was significantly lower than VO(2) at IAT. Our data suggest that portable RGEM provides valuable information concerning the energy expenditure in sports that cannot be interpreted from LA or HR measures alone. Portable RGEM systems provide valuable assessment of under- or over-estimation of requirements of sports and assist in the optimization and interpretation of training in athletes.

Accuracy of neuro-fuzzy logic and regression calculations in determining maximal lactate steady-state power output from incremental tests in humans.

The aim of this study was to employ neuro-fuzzy logic and regression calculations to determine the accuracy of prediction of the power output ( P) of the maximal lactate steady-state (MLSS) on a cycle ergometer calculated from the results of incremental tests. A group of 17 male and 17 female sports students underwent two incremental tests (a 1 min test T(1): initial exercise intensity 0.2 W x kg(-1) increasing 0.2 W x kg(-1) every minute; a 3 min test T(3): initial exercise intensity 0.6 W x kg(-1) increasing 0.6 W x kg(-1) every 3 min) and at least four constant-intensity tests of 30 min duration. Two models for MLSS calculation were developed using the data from T(1) and T(3), a forward stepwise linear regression model (REG) and a neuro-fuzzy model (FUZ). A group of 26 randomly selected subjects (model group, MG) were used to generate the REG and the FUZ models. The data from the remaining 8 subjects (4 men and 4 women; verifying group, VG) were used to verify the REG and FUZ models. The precision of the MLSS calculation in MG produced a better correlation when using data from T(1) (REG r=0.95, FUZ r=0.99) than data from T(3) (REG r=0.88, FUZ r=0.98). Our calculation models were confirmed using data from VG for T(1) (REG r=0.97, FUZ r=0.98) as well as for T(3) (REG r=0.97, FUZ r=0.97). Based on our subject population of young, healthy sport students, our results suggest that a single incremental test may be used for prediction of P at the MLSS using a cycle ergometer. Furthermore, the results from T(1) yielded higher correlations compared to T(3). Calculations from REG were similar to FUZ but the precision of REG and FUZ was better compared to calculations derived using data from a single threshold.