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Biomedical subjects

H Kuipers

Publications and source records attributed to H Kuipers.

At least 19 recordsLinked to original sources
PubMed2006

31P MR spectroscopy and in vitro markers of oxidative capacity in type 2 diabetes patients.

BACKGROUND: Skeletal muscle mitochondrial function in type 2 diabetes (T2D) is currently being studied intensively. In vivo (31)P magnetic resonance spectroscopy ((31)P MRS) is a noninvasive tool used to measure mitochondrial respiratory function (MIFU) in skeletal muscle tissue. However, microvascular co-morbidity in long-standing T2D can interfere with the (31)P MRS methodology. AIM: To compare (31)P MRS-derived parameters describing in vivo MIFU with an in vitro assessment of muscle respiratory capacity and muscle fiber-type composition in T2D patients. METHODS: (31)P MRS was applied in long-standing, insulin-treated T2D patients. (31)P MRS markers of MIFU were measured in the M. vastus lateralis. Muscle biopsy samples were collected from the same muscle and analyzed for succinate dehydrogenase activity (SDH) and fiber-type distribution. RESULTS: Several (31)P MRS parameters of MIFU showed moderate to good correlations with the percentage of type I fibers and type I fiber-specific SDH activity (Pearson's R between 0.70 and 0.75). In vivo and in vitro parameters of local mitochondrial respiration also correlated well with whole-body fitness levels (VO (2peak)) in these patients (Pearson's R between 0.62 and 0.90). CONCLUSION: Good correlations exist between in vivo and in vitro measurements of MIFU in long-standing insulin-treated T2D subjects, which are qualitatively and quantitatively consistent with previous results measured in healthy subjects. This justifies the use of (31)P MRS to measure MIFU in relation to T2D.

Adenosine Diphosphate↗
PubMed2006

[Putative effects of doping in cycling].

After recent scandals in cycling involving doping, it has been asserted that top-level cycling is impossible without pharmacological support. An important prerequisite for successfully completing the Tour de France is maintaining energy balance. To compensate for the daily caloric expenditure of 23-25 MJ, conventional food must be supplemented with liquid food. Quick administration of liquid carbohydrates is essential for optimal recovery of glycogen stores in the liver and skeletal muscle. Androgenic anabolic steroids are a frequently used form of doping. In endurance sports, these drugs have not been shown to affect endurance performance, and there is little evidence to suggest that they enhance recovery. Although epoetin use can increase maximal oxygen uptake, its effects on maximal power output are less pronounced than what is generally assumed. A relationship between haemoglobin concentration and sport performance has not been proved. It has been found that growth hormone rather has a negative than a positive influence on the sport performance. The doping problem is due in part to superstition, hearsay and insufficient knowledge among the athlete's support personnel, which frequently leads to medical malpractice in sport. Education and quality control for sport professionals, including sports physicians, may help to control the doping problem.

Bicycling↗
PubMed2006

Hemoglobin level in elite speed skaters from 2000 up to 2005, and its relationship with competitive results.

We studied the mean hemoglobin (Hb) concentration in elite male and female long track junior and senior speed skaters from 2000 to 2005. In addition, the number of abnormal hematological findings observed over this period of time was investigated. We also studied whether there were differences in Hb concentration between top ranked and lower ranked skaters, and whether a relationship between Hb concentration and competitive results could be observed. The present study shows that the mean Hb level in male and female junior and senior long track speed skaters remained fairly stable and did not change from 2000 through 2005. The number and percentage of abnormal hematological findings were found to vary between 0 and 2 %, and failed to show a clear pattern or trend over the years. There was no difference in mean Hb levels between top ranked and lower ranked skaters, and no meaningful relationship between Hb concentration and ranking could be found.

Female↗
PubMed2006

Comparison of hematologic data in world elite junior speed skaters and in non-athletic juniors.

During the world junior speed skating championship 2002 all athletes (60 males, 56 females) were subjected to hematologic blood testing one day before the competition as requested by International Skating Union--ISU. This study aimed to obtain hematological reference values for junior athletes, whilst the influence of endurance training on hematologic variables of young athletes was studied. Hematologic results of athletes were compared to results of non-athletes matched by age and gender (14 males, 17 females). The blood analysis was done on an ADVIA 120. To compare measurement of ferritin, erythropoietin, and soluble transferrin receptor in serum as well as in EDTA-plasma, serum and EDTA-blood was obtained from the control group. In hemoglobin and hematocrit we found no significant difference between the two groups, whereas the number of erythrocytes was lower in athletes. The mean corpuscular volume was higher in athletes, whilst the corpuscular hemoglobin content was only marginally higher in athletes than in non-athletes. Consequently corpuscular hemoglobin concentration mean was lower in athletes than in non-athletes. There was no difference of erythropoietin and soluble transferrin receptor, whilst in ferritin we found a difference between the groups. Endurance training does not change the values of hemoglobin and hematocrit. Increased mean corpuscular volume and decreased corpuscular hemoglobin concentration mean could be a result of changed properties of red blood cell-membrane caused by acidosis and higher osmolality during the training. In junior athletes we did not find an iron overload as described in some adult athletes.

Adolescent↗
PubMed2006

Injuries in synchronized skating.

Synchronized skating is a relatively new competitive sport and data about injuries in this discipline are lacking. Therefore the purpose of this study was to investigate the frequency and pattern of acute and overuse injuries in synchronized skaters. Before and during the World Synchronized Skating Championship 2004, a questionnaire inquiring about the frequency of injuries in this skating discipline was given to 23 participating teams. A total of 514 women and 14 men senior skaters completed the questionnaires (100 % response). Two hundred and eighteen (42.4 %) female and 6 (42.9 %) male skaters had suffered from acute injuries during their synchronized skating career. As some skaters had suffered from more than one injury, the total number of acute injuries in females was 398 and in males 14. In female skaters 19.8 % of acute injuries were head injuries, 7.1 % trunk, 33.2 % upper, and 39.9 % lower extremity injuries. In male skaters 14.3 % were head injuries, 28.6 % upper, and 57.1 % lower extremity injuries, with no report of trunk injuries. Sixty-nine female and 2 male skaters had low back problems and 112 female and 2 male skaters had one or more overuse syndromes during their skating career. Of 155 overuse injuries in female skaters, 102 (65.8 %) occurred during their figure skating career, while 53 injuries (34.2 %) only occurred when they skated in synchronized skating teams. In male skaters, out of 5 overuse injuries, 4 (80 %) occurred in their figure skating career, while 1 (20 %) occurred during their synchronized skating career. Out of the total of 412 injuries, 338 (82 %) occurred during on-ice practice, while 74 (18 %) happened during off-ice training. Ninety-one (26.9 %) acute injures occurred while practicing individual elements, and 247 (73.1 %) on-ice injuries occurred while practicing different team elements. We conclude that injuries in synchronized skating should be of medical concern due to an increasing number of acute injuries, especially those that go beyond the soft tissue and include head injuries and fractures. We feel that these more significant injuries MAY TO SOME EXTENT BE attributable to the increasing physical demands and technical difficulty required of the teams now participating in a more competitive environment over the last four years.

Adolescent↗
PubMed2006

The effects of creatine supplementation on selected factors of tennis specific training.

BACKGROUND: Creatine supplementation is popular among tennis players but it is not clear whether it actually enhances tennis performance. OBJECTIVES: To examine the effects of creatine supplementation on tennis specific performance indices. METHODS: In a randomised, double blind design, 36 competitive male tennis players (24 creatine, mean (SD) age, 22.5 (4.9) years; 12 placebo, 22.8 (4.8) years) were tested at baseline, after six days of creatine loading, and after a maintenance phase of four weeks (14 creatine, 10 placebo). Serving velocity (10 serves), forehand and backhand velocity (three series of 5x8 strokes), arm and leg strength (bench press and leg press), and intermittent running speed (three series of five 20 metre sprints) were measured. RESULTS: Compared with placebo, neither six days nor five weeks of creatine supplementation had a significant effect on serving velocity (creatine: +2 km/h; placebo: +2 km/h, p = 0.90); forehand velocity (creatine: +4 km/h; placebo: +4 km/h, p = 0.80), or backhand velocity (creatine: +3 km/h; placebo: +1 km/h, p = 0.38). There was also no significant effect of creatine supplementation on repetitive sprint power after 5, 10, and 20 metres, (creatine 20 m: -0.03 m/s; placebo 20 m: +0.01 m/s, p = 0.18), or in the strength of the upper and lower extremities. CONCLUSIONS: Creatine supplementation is not effective in improving selected factors of tennis specific performance and should not be recommended to tennis players.

Adolescent↗
PubMed2005

Skeletal Muscle wasting and contractile performance in septic rats.

We investigated the temporal effects of sepsis on muscle wasting and function in order to study the contribution of wasting to the decline in muscle function; we also studied the fiber-type specificity of this muscle wasting. Sepsis was induced by injecting rats intraperitoneally with a zymosan suspension. At 2 h and at 2, 6, and 11 days after injection, muscle function was measured using in situ electrical stimulation, Zymosan injection induced severe muscle wasting compared to pair-fed and ad libitum fed controls. At 6 days, isometric force-generating capacity was drastically reduced in zymosan-treated rats. We conclude that this was fully accounted fo by the reduction of muscle mas. At day 6, we also observed increased activity of the 20S proteasome in gastrocnemius but not soleus muscle from septic rats. In tibialis anterior but not in soleus, muscle wasting occurred in a fiber-type specific fashion, i.e., the reduction in cross-sectional area was significantly smaller in type 1 than type 2A and 2B/X fibers. These findings suggest that both the inherent function of a muscle and the muscle fiber-type distribution affect the responsiveness to catabolic signals.

Animals↗
PubMed2005

Accidental breaches of the doping regulations in sport: is there a need to improve the education of sportspeople?

OBJECTIVES: To identify educational needs of elite sportspeople with respect to the doping laws. METHODS: A questionnaire survey of 196 Olympic level sportspeople from the fields of athletics, cycling, rowing, and sailing. The questionnaire addressed the date and source of the last doping educational update, the usefulness of current resources, sources of help, and possible ways of improving the system. The questionnaire also sought to estimate the use of nutritional supplements in these sports. RESULTS: Seventy four (38%) athletes responded to the questionnaire. Over 90% of responders had received a doping educational update in the last six months, and most agreed with the statement "I have received the information I need to avoid getting into trouble with the doping laws". Despite this, more than half of responders agreed with the statements "I should receive reminders more often" and "The authorities should do more to educate sportspeople". In addition, there were four people who admitted taking a banned substance by accident. Forty one (55%) reported taking supplements. The team doctor was the most popular source if information on a substance or product was required, with 62% and 66% of subjects stating that they would contact their team doctor when based in the United Kingdom and abroad respectively. The UK Sports website was often suggested in relation to ways of improving knowledge. CONCLUSIONS: There is a need to alter the educational process, particularly with respect to contingency planning for minor illness. The use of internet based resources for up to date information about banned substances needs to be promoted, and access to the internet improved. The educational needs of team doctors with respect to the doping laws need to be assessed.

Adult↗
PubMed2004

Physical activity pattern of children assessed by triaxial accelerometry.

OBJECTIVES: Accelerometry was used to assess the relationship between the physical activity level (PAL) and time spent on activities of various intensities in children. DESIGN: A total of 20 children aged 8.6+/-3.3 y wore a triaxial accelerometer (Tracmor2) for 2 weeks. PAL was calculated with Tracmor2 output data. The fraction of time spent on activities with a given level of intensity (low, moderate, high) was calculated. The fractions of time spent on activities of different intensities were compared with previously obtained data for young adults and elderly persons. RESULTS: PAL showed an inverse relation with the percentage of time spent on low-intensity activities (r = -0.76; P < 0.0001) and a positive relation with the percentage of time spent on high-intensity activities (r = 0.93; P < 0.0001). The fraction of time spent on low-intensity activities was smaller in children than in young adults (P < 0.05) and elderly persons (P < 0.0001), while the fraction spent on high-intensity activities (P < 0.0001) was larger. CONCLUSIONS: The present data are important for a better understanding of physical activity in children, which is necessary for education and prevention about physical (in)activity in childhood. Our observations suggest that to obtain a higher PAL in children, they should be given the opportunities to perform high-intensity activities.

Child↗
PubMed2004

The effect of different nutritional feeds on the postprandial glucose response in healthy volunteers and patients with type II diabetes.

OBJECTIVE: Assessment of postprandial glycaemic response to four nutritional feeds with different macronutrient and fibre composition. DESIGN: A randomized, double-blind, crossover study. SETTING: University of Maastricht, the Netherlands. SUBJECTS: A total of 10 healthy volunteers and 10 patients with type II diabetes. INTERVENTIONS: Subjects received 200 kcal of four enteral nutrition products (two standard products and two diabetes-specific products). Fasting and postprandial plasma glucose were measured for 2 h. Peak glucose level and area under the curve were calculated. RESULTS: In healthy volunteers and diabetic patients, the feed with a low carbohydrate (CHO), high monounsaturated fatty acid (MUFA) and high fibre content significantly decreased peak glucose concentration and area under the curve compared to the feeds with standard composition. CONCLUSIONS: Special feeds with a low CHO, high MUFA and high fibre content improve glycaemic balance and therefore should be considered in diabetic patients who are in need of nutritional support.

Adult↗
PubMed2004

Inhaled salbutamol and endurance cycling performance in non-asthmatic athletes.

Beta(2)-adrenergic agonists are important therapeutic agents for the prevention and treatment of (exercise-induced) asthma in athletes, but may have ergogenic effects. In this study we investigated whether inhalation of a supra-therapeutic dose of 800 microg salbutamol before exercise affects endurance performance during a cycling trial in non-asthmatic athletes. In a double-blind, randomized cross-over study, 16 athletes performed two trials, where they had to perform a certain amount of work as fast as possible on a cycle ergometer, 30 minutes after inhalation of 800 micro g salbutamol or placebo. Peak expiratory flow (PEF), forced vital capacity (FVC), and forced expiratory volume in 1 second (FEV(1)) were measured before and after exercise and blood samples were obtained before and during exercise. Cycling performance time was 4010.2 +/- 327.7 s after placebo inhalation and 3927.6 +/- 231.3 s after inhalation salbutamol (p < 0.05). Although salbutamol inhalation increased plasma free fatty acids, glycerol and lactate concentrations and decreased plasma potassium concentrations at rest, no differences between placebo and salbutamol in these variables were found during exercise. PEF and FEV(1) were increased after salbutamol inhalation at rest compared with placebo, but the difference between placebo and salbutamol after exercise was no longer significant. Inhalation of a supratherapeutic dose of 800 micro g salbutamol improved endurance cycling performance by 1.9 +/- 1.8 % in non-asthmatic athletes, which indicates that this route of administration does not exclude the possibility of an ergogenic effect of beta(2)-adrenergic agents in athletes. The increase in performance was not explained by changes in plasma concentrations of free fatty acids, glycerol, lactate, and potassium during exercise or by changes in ventilatory parameters at rest and after exercise. Therefore, the mechanism of the increase in performance remains to be determined.

Administration, Inhalation↗
PubMed2004

Effects of androgenic-anabolic steroids on apolipoproteins and lipoprotein (a).

OBJECTIVES: To investigate the effects of two different regimens of androgenic-anabolic steroid (AAS) administration on serum lipid and lipoproteins, and recovery of these variables after drug cessation, as indicators of the risk for cardiovascular disease in healthy male strength athletes. METHODS: In a non-blinded study (study 1) serum lipoproteins and lipids were assessed in 19 subjects who self administered AASs for eight or 14 weeks, and in 16 non-using volunteers. In a randomised double blind, placebo controlled design, the effects of intramuscular administration of nandrolone decanoate (200 mg/week) for eight weeks on the same variables in 16 bodybuilders were studied (study 2). Fasting serum concentrations of total cholesterol, triglycerides, HDL-cholesterol (HDL-C), HDL2-cholesterol (HDL2-C), HDL3-cholesterol (HDL3-C), apolipoprotein A1 (Apo-A1), apolipoprotein B (Apo-B), and lipoprotein (a) (Lp(a)) were determined. RESULTS: In study 1 AAS administration led to decreases in serum concentrations of HDL-C (from 1.08 (0.30) to 0.43 (0.22) mmol/l), HDL2-C (from 0.21 (0.18) to 0.05 (0.03) mmol/l), HDL3-C (from 0.87 (0.24) to 0.40 (0.20) mmol/l, and Apo-A1 (from 1.41 (0.27) to 0.71 (0.34) g/l), whereas Apo-B increased from 0.96 (0.13) to 1.32 (0.28) g/l. Serum Lp(a) declined from 189 (315) to 32 (63) U/l. Total cholesterol and triglycerides did not change significantly. Alterations after eight and 14 weeks of AAS administration were comparable. No changes occurred in the controls. Six weeks after AAS cessation, serum HDL-C, HDL2-C, Apo-A1, Apo-B, and Lp(a) had still not returned to baseline concentrations. Administration of AAS for 14 weeks was associated with slower recovery to pretreatment concentrations than administration for eight weeks. In study 2, nandrolone decanoate did not influence serum triglycerides, total cholesterol, HDL-C, HDL2-C, HDL3-C, Apo-A1, and Apo-B concentrations after four and eight weeks of intervention, nor six weeks after withdrawal. However, Lp(a) concentrations decreased significantly from 103 (68) to 65 (44) U/l in the nandrolone decanoate group, and in the placebo group a smaller reduction from 245 (245) to 201 (194) U/l was observed. Six weeks after the intervention period, Lp(a) concentrations had returned to baseline values in both groups. CONCLUSIONS: Self administration of several AASs simultaneously for eight or 14 weeks produces comparable profound unfavourable effects on lipids and lipoproteins, leading to an increased atherogenic lipid profile, despite a beneficial effect on Lp(a) concentration. The changes persist after AAS withdrawal, and normalisation depends on the duration of the drug abuse. Eight weeks of administration of nandrolone decanoate does not affect lipid and lipoprotein concentrations, although it may selectively reduce Lp(a) concentrations. The effect of this on atherogenesis remains to be established.

Adult↗
PubMed2004

Physical activity as measured by accelerometry in children receiving growth hormone.

AIM: Parents of children treated with growth hormone (GH) frequently report to the paediatrician that their children have become more physically active. In the present study, activity patterns of GH-treated children were measured and compared to those of healthy controls. METHODS: Subjects were 25 children at the start of GH treatment (age 8.4 +/- 2.6 y) and 19 age- and gender-matched controls (age 8.8 +/- 3.2 y). Physical activity was assessed with a tri-axial accelerometer for movement registration over two separate 2-wk intervals, one before the start of GH treatment and one 2 wk after the start of treatment. GH-treated subjects were categorized as poor responders (change in height over 1 y <0.7 SDS, n = 15) or good responders (change in height over 1 y >0.7 SDS, n = 10). RESULTS: Before therapy, good responders showed a significantly lower physical activity compared to healthy controls, spending significantly less time on high-intensity activities. This difference disappeared 2 wk after the start of therapy. Physical activity in poor responders was not significantly different from controls before and after 2 wk of GH therapy. CONCLUSION: Children who respond well to GH therapy (change in height >0.7 SDS) showed a reduced amount of physical activity before therapy, which was normalized after 2 wk of GH therapy.

Arginine↗
PubMed2003

Rapid visuomotor preparation in the human brain: a functional MRI study.

An important feature of human motor behaviour is anticipation and preparation. We report a functional magnetic resonance imaging study of the neuronal activation patterns in the human brain that are associated with the rapid visuomotor preparation of discrete finger responses. Our imaging results reveal a large-scale distributed network of neural areas involved in fast visuomotor preparation, including specific areas in the frontal cortex (middle frontal gyrus, premotor and supplementary motor cortex), the parietal cortex (intra-parietal sulcus, inferior and superior parietal lobe) and the basal ganglia. Our reaction time results demonstrate that it is easier to prepare two fingers on one hand than on two hands. This hand-advantage phenomenon was associated with relatively enhanced levels of activity in the basal ganglia and relatively reduced levels of activity in the parietal cortex. These findings provide direct evidence for differential activity in a distributed brain system associated with specific neuro-computational operations subserving fast visuomotor preparation.

Adult↗
PubMed2003

Androgenic anabolic steroid use and severe hypothalamic-pituitary dysfunction: a case study.

The data of the present case demonstrate that the abuse of androgenic anabolic steroids (AAS) may lead to serious health effects. Although most clinical attention is usually directed towards peripheral side effects, the most serious central side effect, hypothalamic-pituitary-dysfunction, is often overlooked in severe cases. Although this latter central side-effect usually recovers spontaneously when AAS intake is discontinued, the present case shows that spontaneous recovery does not always take place. We suggest that hypothalamic-pituitary dysfunction should always be considered in the differential diagnosis in athletes seen with typical presentation of anabolic steroid use. In order to regain normal hypothalamic-pituitary function, supraphysiological doses of 200 microg LH-RH should be considered when the physiological challenge test with LH-RH (50 microg) fails to show an acceptable response.

Adult↗
PubMed2003

Prospective echocardiographic assessment of androgenic-anabolic steroids effects on cardiac structure and function in strength athletes.

Since the abuse of androgenic-anabolic steroids (AAS) has been associated with the occurrence of serious cardiovascular disease in young athletes, we performed two studies to investigate the effects of short-term AAS administration on heart structure and function in experienced male strength athletes, with special reference to dose and duration of drug abuse. In Study 1 the effects of AAS were assessed in 17 experienced male strength athletes (age 31 +/- 7 y) who self-administered AAS for 8 or 12 - 16 weeks and in 15 non-using strength athletes (age 33 +/- 5 y) in a non-blinded design. In Study 2 the effects of administration of nandrolone decanoate (200 mg/wk i. m.) for eight weeks were investigated in 16 bodybuilders in a randomised double blind, placebo controlled design. In all subjects M-mode and two-dimensional Doppler-echocardiography were performed at baseline and after 8 weeks AAS administration. In the athletes of Study 1 who used AAS for 12 - 16 weeks a third echocardiogram was also made at the end of the AAS administration period. Echocardiographic examinations included the determination of the aortic diameter (AD), left atrium diameter (LA), left ventricular end diastolic diameter (LVEDD), interventricular septum thickness (IVS), posterior wall end diastolic wall thickness (PWEDWT), left ventricular mass (LVM), left ventricular mass index (LVMI), ejection fraction (EF) and right ventricular diameter (RVD). For assessment of the diastolic function measurements of E and A peak velocities and calculation of E/A ratio were used. In addition, acceleration and deceleration times of the E-top (ATM and DT, respectively) were determined. For evaluation of factors associated with stroke volume the aorta peak flow (AV) and left ventricular ejection times (LVET) were determined. In Study 1 eight weeks AAS self-administration did not result in changes of blood pressure or cardiac size and function. Additionally, duration of AAS self-administration did not have any impact on these parameters. Study 2 revealed that eight weeks administration of nandrolone decanoate did not induce significant alterations in blood pressure and heart morphology and function. Short-term administration of AAS for periods up to 16 weeks did not lead to detectable echocardiographic alterations of heart morphology and systolic and diastolic function in experienced strength athletes. The administration regimen used nor the length of AAS abuse did influence the results. Moreover, it is concluded that echocardiographic evaluation may provide incomplete assessment of the actual cardiac condition in AAS users since it is not sensitive enough to detect alterations at the cellular level. Nevertheless, from the present study no conclusions can be drawn of the cardiotoxic effects of long term AAS abuse.

Adult↗
PubMed2003

Effects of stage duration in incremental running tests on physiological variables.

To study the effect of stage duration on some physiological variables in an incremental running test, 8 well-trained runners underwent 3 running tests, with stage durations of 1, 3 and 6 min. To study maximal lactate steady state (maxLASS) and its corresponding speed, every subject underwent a 4th test with three 15-min stages at three speeds, based on the running speed at 4 mmol/l blood lactate (V4) in the 6 min per stage protocol. The first load in the 15 min per stage test was V4 - 0.5 km/h, the second at V4, and the third V4 + 0.5 km/h. To compare the maxLASS speed with outdoor performance, the subjects also ran 5 km at this speed on an outdoor track. Mean maximal running speed (V (max)) in the incremental test was significantly lower in the 6-min (15.1 km/h) and 3-min stage protocol (17.1 km/h), compared with the 1-min stage protocol (18.3 km/h). Mean peak VO (2) and mean peak heart rate were not different between the protocols with different stage duration. The mean V4 was significantly lower in the 6 min per stage protocol compared with the 3 min per stage protocol (12.9 vs. 14.4 km/h). Mean ventilatory threshold was not different between the 1, 3 and 6 min per stage protocols. No threshold behaviour was found in respiratory rate. MaxLASS can be estimated from V4 in the 6 min per stage protocol, and verified by three 15-min intensities being V4 - 0.5 km/h, at V4, and V4 + 0.5 km/h. The mean blood lactate concentration at the maxLASS speed was not different between treadmill running and outdoor running on a track. In conclusion, for measuring peak values of physiological variables in an incremental running test, the duration per stage is of less importance, however, when measuring blood lactate concentration as a function of running speed, the duration per stage should be at least 6 min.

Adult↗