Maximal Cycle Ergometer Exercise Research Articles

Physiological Effects of Two Different Postactivation Potentiation Training Loads on Power Profiles Generated During High Intensity Cycle Ergometer Exercise

The purpose of this study was to investigate whether postactivation potentiation (PAP) would have any effect on high intensity cycle ergometer performance. Two different squatting exercises of different loads were presented in a random fashion prior to ergometric exercise. Seven male rugby players volunteered to participate in the study. There were no significant differences observed between peak power output (PPO) measurements for all three testing conditions (P > 0.05). There were also no differences recorded between mean power outputs (MPOs) and end power outputs (EPOs) (P > 0.05). The decrease in power output (FI %) also was found to be nonsignificant for all conditions (P > 0.05). The findings of this study indicate that performance of repeated heavy squats prior to a 30-second maximal cycle ergometer exercise did not improve the power profiles recorded and did not induce PAP at the time of testing.

Możliwości wnioskowania o zdolności wysiłkowej chorych na przewlekłą obturacyjną chorobę płuc na podstawie krzywej maksymalnego przepływu i objętości

Patients with chronic obstructive pulmonary disease (COPD) often present reduced exercise tolerance. Limitation of exercise capacity in COPD is an essential feature, which can be accurately determined by incremental cycle ergometry. The relationship between resting lung function variables and exercise capacity has been studied extensively in COPD patients. A clear relationship between resting pulmonary function testing and exercise capacity has not been established. The present study was designed to assess the accuracy of new index such as area under the maximal expiratory flow-volume curve [A(ex)] in predicting exercise capacity (expressed by maximum oxygen uptake - V'O(2max) and maximal mechanical work - W(max)) in COPD patients. The study was performed on 41 patients with mild - to severe COPD (FEV1, 57.2 +/- 15.3% predicted). Each subject underwent resting spirometry (area under the maximal expiratory flow-volume curve - A(ex) was calculated). Subsequently, they performed maximal incremental cycle ergometer exercise for determination of V'O(2max), W(max). Significant correlation was found between A(ex) and V'O(2max) (r = 0.57, p < 0.001). In the group of severe COPD significant correlation was found between A(ex) and W(max) (r = 0.50 p < 0.05). In chronic obstructive pulmonary disease, the index - area under the maximal expiratory flow-volume curve - A(ex), could be useful in assesment of COPD severity and in predicting exercise capacity.

Is Delayed Post-exercise Blood Pressure Recovery A Marker For Metabolic Syndrome In Young Men?

Metabolic syndrome (MetS), an increasingly prevalent disorder, is denned by a cluster of cardio-metabolic risk factors including obesity, dyslipidemia, and hypertension. Autonomic dysfunction has been linked to chronic diseases arising from these risk factors. Following exercise, heart rate (HR) and blood pressure (BP) return to resting levels by parasympathetic activation and sympathetic withdrawal. Therefore, altered response patterns for these measures in post-exercise recovery have increasingly been accepted as markers of autonomic imbalance. MetS is associated with increased sympathetic activity, but little is known about the relationship between MetS and post-exercise autonomic balance, especially in young men. PURPOSE: To evaluate whether measures of autonomic balance, including post-exercise HR and BP recovery, are altered in young men with MetS. METHODS: Subjects included 8 young men (BMI: Mean ± SD = 33.4 ± 7.0 kg/m2; age = 21.6 ± 3.7 yr) with MetS and 9 without MetS (BMI = 21.9 ± 1.5 kg/m2; age = 22.0 ± 3.0 yr). The National Cholesterol Education Program standards (ATP III. Circulation, 2002) define MetS as having 3 or more of the following: elevated fasting blood glucose or triglycerides, pre-hypertension, abdominal obesity, or reduced HDL-C. Subjects performed a maximal effort cycle ergometer exercise test using a δ15W/ min ramping protocol. HR, systolic and diastolic blood pressure (SBP and DBP) and oxygen consumption (VO2) were recorded during exercise. Cardiovascular responses were evaluated at 15sec intervals during active recovery. RESULTS: Relative VO2pk, HR and SBP did not differ between groups at rest or at peak exercise. In recovery cardiovascular responses, only SBP was higher in the MetS group across minutes 1–5 min (p = 0.026). Similar assessments by Sung et al. (J Korean Med Sci, 2006) in older adults with MetS have shown delayed HR recovery following exercise, but not a delayed SBP response. CONCLUSIONS: Attenuated post-exercise BP recovery occurs in sedentary young men with MetS. Recovery responses provide useful information about autonomic balance and increase the clinical utility of the test.

Intravascular ADP and soluble nucleotidases contribute to acute prothrombotic state during vigorous exercise in humans

Extracellular ATP and ADP trigger vasodilatatory and prothrombotic signalling events in the vasculature. Here, we tested the hypothesis that nucleotide turnover is activated in the bloodstream of exercising humans thus contributing to the enhanced platelet reactivity and haemostasis. Right atrial, arterial and venous blood samples were collected from endurance-trained athletes at rest, during submaximal and maximal cycle ergometer exercise, and after early recovery. ATP-specific bioluminescent assay, together with high-performance liquid chromatographic analysis, revealed that plasma ATP and ADP concentrations increased up to 2.5-fold during maximal exercise. Subsequent flow cytometric analysis showed that plasma from exercising subjects significantly up-regulated the surface expression of P-selectin in human platelets and these prothrombotic effects were diminished after scavenging plasma nucleotides with exogenous apyrase. Next, using thin layer chromatographic assays with [gamma-(32)P]ATP and (3)H/(14)C-labelled nucleotides, we showed that two soluble nucleotide-inactivating enzymes, nucleotide pyrophosphatase/phosphodiesterase and nucleoside triphosphate diphosphohydrolase, constitutively circulate in human bloodstream. Strikingly, serum nucleotide pyrophosphatase and hydrolase activities rose during maximal exercise by 20-25 and 80-100%, respectively, and then declined after 30 min recovery. Likewise, soluble nucleotidases were transiently up-regulated in the venous blood of sedentary subjects during exhaustive exercise. Human serum also contains 5'-nucleotidase, adenylate kinase and nucleoside diphosphate (NDP) kinase; however, these activities remain unchanged during exercise. In conclusion, intravascular ADP significantly augments platelet activity during strenuous exercise and these prothrombotic responses are counteracted by concurrent release of soluble nucleotide-inactivating enzymes. These findings provide a novel insight into the mechanisms underlying the enhanced risk of occlusive thrombus formation under exercising conditions.

Muscular Strength, Aerobic Fitness, and Metabolic Syndrome Risk in Flemish Adults

To investigate the association of muscular strength and aerobic fitness with a continuous metabolic syndrome risk score in male and female adults. This cross-sectional study included 1019 (571 men) Flemish adults, aged 18-75. Muscular strength was evaluated by measuring isometric knee extension and flexion peak torque, using a Biodex System Pro 3 dynamometer. Aerobic fitness was quantified as VO2peak and was determined during a maximal cycle ergometer exercise test. Both strength and aerobic fitness were scaled for differences in FFM, using allometric analyses. A validated metabolic syndrome risk score that was based on waist circumference, triglycerides, blood pressure, fasting plasma glucose, and HDL cholesterol was used. Metabolic syndrome risk score, strength, and aerobic fitness were analyzed as continuous variables using multiple linear regression. Metabolic syndrome risk was inversely associated with strength, independently of aerobic fitness, and after adjustment for age, height, education level, smoking status, and dietary intake in women (beta = -0.172, P < 0.001). In men, however, adjustment for aerobic fitness attenuated the inverse association between strength and metabolic syndrome risk (beta = -0.044, P > 0.05). Independently of strength, aerobic fitness was inversely associated with metabolic syndrome risk (men: beta = -0.309, P < 0.001; women: beta = -0.208, P < 0.001). Furthermore, independent associations were found for strength and aerobic fitness with several individual metabolic syndrome risk factors in women, and most of these associations were only partially mediated by central and general adiposity indicators. Although cross-sectional, the present results support inclusion of strength training in addition to aerobic exercise in physical activity recommendations for women, because both types of activity might show additional effects in reducing the risk of the metabolic syndrome.

Legcycling Improves the Oxygenation in Relaxed Shoulder Muscles

Physical activity can reduce the risk for e.g. cardiovascular diseases, however only relatively few studies have considered the effect of physical activity upon muscle pain e.g. in trapezius myalgia. Training of the painful muscles itself may have a positive effect but compliance may be low for such intervention due to pain being provoked. We therefore hypothesized that training of other large muscle groups may have an effect even upon the oxygenation of the passive muscles mediated by the systemic cardiovascular response to exercise. Thus even though the painful shoulder muscles are not directly trained they could benefit from an increased oxygen availability due to leg exercise PURPOSE: To determine the oxygenation in the passive upper trapezius muscles during leg cycling together with systemic blood pressure. METHODS: Five healthy female subjects and 13 female patients diagnosed with trapezius myalgia in one or both shoulder. The most painful shoulder (P) was compared to the dominant side of the healthy subjects (D). The subjects performed 20 min sub maximal cycle ergometer exercise with their arms hanging relaxed along the side. The exercise started at a level of 55% of maximal heart rate for 10 min. and was increased to 70% for the last 10 min. The exercise was followed by a 5 min. recovery period. Muscle tissue oxygenation was measured using Near Infrared Spectroscopy, NIRS (NIRO 300 Hamamatsu, Japan). The NIRS probes were placed bilaterally on the upper trapezius muscles. Blood pressure was measured continuously with a finger cuff on the right hand (Finometer, Finland). Five measurements of 30 s. were analysed: in the beginning (after 11/2 min.), 1. steady state, 2.steady state, in the end of the work period (19 min.) and 2 min. after the exercise (recovery). RESULTS: For all subjects an increase in oxygenation was found for both shoulders from start to end (P/D: 0,4±1 – 6±3; NoP/NonD: −0,7±1 – 5±3μM) with an even larger increase in the recovery period. (P/D: 8±4; NoP/NonD: 8±3μM). No increase in BP was found neither in systolic nor diastolic pressure but a tendency to a small decrease was present (179/65±23/13 – 165/61±31/11 mmHg).When the painful shoulder of the patients with diagnosed trapezius myalgi were compared to healthy subjects a significantly higher oxygenation was present in the end of the working period and in the recovery period for the healthy subjects. CONCLUSION: Exercise with large muscle groups has an effect upon small muscles at rest regarding oxygenation, this effect is larger in non myalgic shoulders.

Does OSA Distort Perception of Aerobic Exercise Capacity?

Obstructive Sleep Apnea (OSA) is characterized by intermittent nocturnal airway occlusion, sleep fragmentation, and oxygen desaturation. OSA patients report a lower quality of life attributed to excess daytime sleepiness, fatigue, irritability, and impaired cognition. In addition, the great majority of OSA patients are obese and at increased risk for cardiovascular (CV) disease. It has been suggested that this symptom set reduces the perceptions of their ability to engage in and perform physical activities, including participation in aerobic exercise. Thus, encouragement of regular exercise as an adjunct to managing their obesity and excess CV health risks is not seen as viable. PURPOSE: To determine if OSA patients have a distorted perception of their aerobic exercise capacity. METHODS: Forty three sedentary individuals (Mean age ± SD = 36.1 ± 14.4 yr, BMI 31.5 ± 7.9 kg/m2 76% males) with diagnosed OSA [Apnea Hypopnea Index (AHI) = 18.3 ± 13.1 events/hr] were compared to a similar group of 34 controls (27.5 ± 9.4 yr, BMI 28.1 ± 6.1 kg/m2 86% males) without OSA (AHI = 3.2 ± 1.5 events/hr). All were assessed by full overnight laboratory or with at-home polysomnography screening (Medcare, Reykjavik, Iceland). Each completed the Medical Outcomes Study Short Form-36 (SF-36), Veterans Specific Activity Questionnaire (VSAQ), Epworth Sleepiness Scale (ESS), and maximal effort cycle ergometer exercise test using a Δ15W ramping protocol. EPDS, an “Exercise Perception Distortion Score,” [(VO2pk -VO2pk predicted from VSAQ)/VO2pk × 100] was devised to represent distortion in the capability to self-estimate aerobic capacity. RESULTS: OSA and Non-OSA groups did not differ in measured VO2pk or the EPDS. Self-rating of aerobic exercise capacity by age-adjusted VSAQ was highly correlated to VO2pk for the entire sample (n = 77: r = 0.96, p<0.01), and within both the OSA (r = 0.98, p<0.01) and Non-OSA (r = 0.96, p<0.01) groups. The OSA patients reported more sleepiness (ESS, p<0.01), lower physical functioning (PF subscale, p<0.01), and lower role physical scores (RP subscale, p<0.01) than the Non-OSA group. CONCLUSION: Untreated OSA patients perceive themselves as sleepier and less able to engage in low-intensity physical activity. Yet, judgment of their aerobic exercise capacity is accurate and similar to that reported by sedentary individuals without OSA. These results encourage further research to evaluate the efficacy of moderate-vigorous exercise as an adjunct to medical management of CV disease risks in OSA patients. Supported by a grant from ResMed Sleep Disordered Breathing Foundation, Poway, CA.

Association Between Graded Exercise Test Indicators of Cardiovascular Disease Risks and Peripheral Vascular Stiffness

Exaggerated systolic blood pressure (SBP) responses to graded exercise testing in normotensive adults have been associated with risk of future hypertension. Venous occlusion plethysmography (VOP) non-invasively characterizes endotheliumdependent vasodilatory capacity in peripheral arteries (reactive hyperemia: RH). Endothelial dysfunction has been hypothesized to lead to functional and structural changes in resistance vessels and also contribute to increased risk for future hypertension. Limited research has been done to assess the relationship between exaggerated SBP in exercise testing and vascular status by the VOP/RH test in young normotensive adults. PURPOSE: To determine if an association exists between exaggerated SBP responses to graded exercise and peripheral vascular vasodilatory capacity. METHODS: Subjects were 50 young males (Mean ± SD: age = 22.4 ± 2.6 yr; body fat = 24.3 ± 6.1 %; BMI = 27.7 ± 5.7). Post-occlusive RH was assessed after a 5-min brachial artery occlusion using VOP and standard procedures recommended by the manufacturer (Hokanson EC-6, Bellevue, WA). Each subject performed maximal cycle ergometer exercise tests with a 15 watts/min ramping protocol. Blood pressures (BP) were measured at rest, every 2 min during, and at 15 sec intervals after exercise. Subjects recovered in the seated position, with minimal-load pedaling. Exaggerated BP was defined as any one of the following: SBP at METpk >195 mm Hg; Δ SBP >60 mm Hg at 35% METpk; Δ SBP >70 mm Hg at 65% METpk and (4) Δ diastolic BP >10 mm Hg at METpk. RESULTS: Resting SBP showed modest (r ∼ 0.33) but statistically significant (p<0.02) associations with RH scores from 30–60 sec post-occlusion. However, during exercise no relationship was found between any of the exaggerated SBP indices and the measures of peripheral artery status by VOP. DBP at 4 min post-exercise was significantly associated with RH immediately post-occlusion (r = 0.28, p = 0.04). Furthermore, when individual SBP responses from peak exercise at the highest (200–246 mmHg) vs. lowest tertiles (138–176 mmHg) were contrasted, no differences in the VOP measures of vascular status were found. CONCLUSION: Regulations of blood pressure at rest and during exercise are complex and the mechanisms by which vascular status may contribute to risk of hypertension remain poorly understood, especially with respect to younger vs. older adults. Within the limitations of this study, exaggerated SBP response to graded exercise in young adult males seems to be regulated largely by factors other than peripheral vascular status, as assessed by VOP/RH. Supported by a grant from ResMed Sleep Disordered Breathing Foundation, Poway, CA.

Regular physical exercise, heart rate variability and turbulence in a 6-year randomized controlled trial in middle-aged men: The DNASCO study

HRV and HRT are independent predictors of cardiovascular mortality. Aging reduces HRV, but results from the physical exercise trials are controversial. The primary aim was to study changes in heart rate variability (HRV) and heart rate turbulence (HRT) in a six-year controlled randomized trial at regular low to moderate intensity physical exercise. One hundred forty men aged 53–63 years were randomized in to an exercise or a control groups. The participants underwent a maximal bicycle ergometer exercise test with respiratory gas analyses annually for six years. At baseline and after intervention, 24-h ambulatory ECG registrations were performed to assess HRV ( n = 100). HRT was determined among subjects with single ventricular premature complexes (VPC) ( n = 73). In the exercise group, ventilatory aerobic threshold (VAT) increased by 16% indicating enhanced submaximal cardiorespiratory fitness. No significant differences were found in any of the HRV or HRT parameters between the groups. However, the observed increase in VAT correlated significantly with the improvement in HRV parameters. The change in turbulence slope (TS) correlated with the changes in most HRV variables and the change in turbulence onset (TO) correlated with the changes in three frequency domain parameters. Our results suggest that in addition to improvement in submaximal cardiorespiratory fitness, regular low to moderate intensity physical exercise seems to have beneficial effects also on cardiac autonomic nervous function, a clinically relevant predictor of cardiovascular morbidity and mortality.

Effects of montelukast on airway narrowing from eucapnic voluntary hyperventilation and cold air exercise

Background: Exercise induced bronchoconstriction (EIB) is common in elite athletes. Eucapnic voluntary hyperventilation (EVH) is a laboratory test recommended for the identification of EIB in athletes, secondary to a field...

Effect of antioxidant vitamin treatment on the time course of hematological and hemorheological alterations after an exhausting exercise episode in human subjects

This study examined the effects of a 2-mo antioxidant vitamin treatment on acute hematological and hemorheological alterations induced by exhausting exercise; both sedentary and trained individuals were employed. Eighteen young male, human subjects (9 sedentary, 9 trained by regular exercise) participated in the study and performed an initial maximal aerobic cycle ergometer exercise with frequent blood sampling over a 24-h period and analysis of hematological and hemorheological parameters. All subjects were treated with an antioxidant vitamin A, C, and E regimen, supplemented orally for 2 mo, and then subjected to a second exercise test and blood sampling at the end of this period. In the sedentary group during the first testing period (before vitamin treatment), white blood cell counts and granulocyte percentages were increased at 2 h after the exercise test and remained elevated for 4-12 h. Red blood cell (RBC) deformability and aggregation were also altered by exercise in the sedentary group before vitamin treatment. However, none of these parameters in the sedentary group were altered by exercise after the 2-mo period of antioxidant vitamin treatment. With the exception of a transient rise in granulocyte percentage, these parameters were also not affected in the trained subjects before the vitamin treatment. Significant increases of RBC lipid peroxidation observed 12 h after the exercise test in both sedentary and trained subjects were also totally prevented by vitamin treatment. Our results indicate that antioxidant vitamin treatment is effective in preventing the inflammation-like response and coincident adverse hemorheological changes after an episode of exhausting exercise, and suggest that such changes may be related to exercise-induced death events.

LOW SUBMAXIMAL HEART RATE PROTECTS FROM PREMATURE CARDIOVASCULAR DEATH IN MEN

High heart rate (HR) at predetermined submaximal workload is a risk factor for premature cardiovascular disease (CVD) death. High HR at submaximal workload may indicate a low maximal cardiovascular capacity, although the relation between HR at submaximal workload and CVD death is not clearly verified. PURPOSE To prospectively investigate the independent association of submaximal heart rate (submaxHR) with CVD mortality in middle-aged men examined in 1984–9 in the KIHD study. METHODS The subjects were a population-based sample of 1305 men (42–61 years) from eastern Finland with neither prior coronary heart disease (CHD) nor the use of b-blockers at baseline. HR was measured from electrocardiogram during a symptom limited maximal bicycle ergometer exercise test. SubmaxHR was defined as an average of HR at workloads of 120 and 140 watts. Deaths were obtained from the national death certificate register. RESULTS There were 122 deaths during an average follow-up of 11.5 years. Of these 49 and 33 were due to CVD and CHD respectively. In a Cox regression model, the associations of submaxHR with CVD and CHD mortality were not linear (p = 0.13 and p = 0.11 for linear trend) after adjustment for known CVD risk factors and directly measured maximal oxygen uptake (maxVO2). When compared with the lowest tertile of submaxHR, the relative risks (RRs) of CVD death in other tertiles were 2.5 (95% CI 1.1;5.9, p = 0.04) and 2.4 (1.0;5.7, p = 0.05) indicating more threshold-like association. The respective RRs for CHD death were 3.7 (1.1;11.9, p = 0.03) and 3.5 (1.1;11.1, p = 0.03). CONCLUSION The low submaximal heart rate was associated with a lower risk of premature CVD and CHD death in middle-aged male population. This association was not largely explained by maxVO2, as previously suggested, referring to a different mediating mechanism such as a parasympathetic predominance of autonomic nervous system balance protecting from fatal arrhytmias.

SUBMAXIMAL OXYGEN PULSE PREDICTS TOTAL AND CARDIOVASCULAR MORTALITY IN MEN

Low maximal cardiorespiratory capacity is an important risk factor for cardiovascular disease (CVD), while the role of directly measured submaximal cardiorespiratory capacity in the prediction of CVD is unknown. PURPOSE: To investigate the association of submaximal oxygen pulse (submaxVO2/HR) as an indicator of submaximal cardiorespiratory capacity with mortality in 1,928 Finnish 42–60 year old men examined in 1984–9 in the Kuopio Ischaemic Heart Disease Risk Factor Study (KIHD). METHODS: Oxygen consumption (VO2) was measured directly by breath-by-breath method and heart rate (HR) was measured from recorded electrocardiogram in a symptom limited maximal bicycle ergometer exercise test. Submax VO2/HR was defined as the highest VO2/HR-value during the phase of the test when respiratory quotient (RQ) was in the range of 0.95–0.99. Deaths were obtained from the national death certificate register. RESULTS: There were 246 deaths during an average follow-up of 11.4 years. Of these, 111 were due to CVD. In a Cox regression model adjusted for age, CVD, cancer, cigarette smoking and alcohol consumption at baseline, submaxVO2/HR as a continuous variable was inversely associated with the risk of any death (p < 0.001) and CVD death (p = 0.001). When compared with the highest quintile of submaxVO2/HR, the relative risks (RRs) of any death in other quintiles were 0.80 (95% CI 0.49;1.31), 1.32 (0.85;2.05), 1.32 (0.85;2.06) and 2.02 (1.34;3.03, p = 0.001) (p < 0.001 for linear trend). The respective RRs for CVD death were 0.96 (0.45;2.03), 1.52 (0.76;3.01), 1.50 (0.76;2.97) and 2.33 (1.24;4.40, p = 0.009) (p = 0.001 for linear trend). These associations were in part explained by blood pressure, diabetes and plasma fibrinogen at baseline. CONCLUSION: SubmaxVO2/HR, a safe and objective method to quantify submaximal cardiorespiratory capacity, appears to be a valuable tool in the prediction of total and CVD mortality in middle-aged men.

Exercise performance in tetralogy of Fallot: the impact of primary complete repair in infancy.

Primary complete repair (PCR) of tetralogy of Fallot (TOF) is now routinely performed in infancy. Although operative results are excellent, the impact on exercise performance is incompletely understood. We reviewed data of all children with TOF who underwent PCR at our institution and had subsequent maximal cycle ergometer exercise testing between January 1995 and December 2000. Of the 193 patients with TOF who underwent PCR, 57 (30%) underwent exercise testing; maximal tests were available for 50 of 57 (88%). Exercise performance of subjects who underwent PCR at <1 year of age was compared to that of those who underwent repair at >l year of age. The median age at PCR was 10.9 months; 28 subjects (56%) underwent PCR in infancy (<1 year). A transannular incision was employed in the repair in 41 subjects (82%). The mean age at exercise testing was 12.5 +/- 3.2 years. The mean maximal VO2 was 94.9 +/- 18.8% predicted and the mean maximal work rate was 98.0 +/- 20.8% predicted. In multivariate analysis PCR in infancy (age <1 year) was not associated with maximal VO2, peak work rate, peak heart rate, or arrhythmias. Only older age at testing and male gender were significantly associated with higher maximal VO2 (p = 0.005 and p = 0.002, respectively). Intermediate-term exercise performance in subjects who undergo PCR of TOF in early childhood is near normal. Performing PCR in the first year of life does not impact subsequent exercise performance.

Growth hormone responses to repeated maximal cycle ergometer exercise at different pedaling rates

The present study examined the growth hormone (GH) response to repeated bouts of maximal sprint cycling and the effect of cycling at different pedaling rates on postexercise serum GH concentrations. Ten male subjects completed two 30-s sprints, separated by 1 h of passive recovery on two occasions, against an applied resistance equal to 7.5% (fast trial) and 10% (slow trial) of their body mass, respectively. Blood samples were obtained at rest, between the two sprints, and for 1 h after the second sprint. Peak and mean pedal revolutions were greater in the fast than the slow trial, but there were no differences in peak or mean power output. Blood lactate and blood pH responses did not differ between trials or sprints. The first sprint in each trial elicited a serum GH response (fast: 40.8 +/- 8.2 mU/l, slow: 20.8 +/- 6.1 mU/l), and serum GH was still elevated 60 min after the first sprint. The second sprint in each trial did not elicit a serum GH response (sprint 1 vs. sprint 2, P < 0.05). There was a trend for serum GH concentrations to be greater in the fast trial (mean GH area under the curve after sprint 1 vs. after sprint 2: 1,697 +/- 367 vs. 933 +/- 306 min x mU(-1) x l(-1); P = 0.05). Repeated sprint cycling results in an attenuation of the GH response.

FUNCTIONAL ABILITY AND FUNCTIONAL CAPACITY IN PATIENTS WITH PARKINSON??S DISEASE

Functional ability and the ability to carry out activities of daily living are integrally related to functional capacity. The Timed Up and Go test and the 6-Minute Walk are measures of functional ability commonly employed in the clinical setting, but there has been limited evaluation of how these tests compare with tests of functional capacity, particularly in patients with Parkinson's Disease. Seventeen male patients with Parkinson's Disease (Hoehn-Yahr stages 1–3; mean age 57 ± 12 years) completed 2 tests of functional ability: the 6-Minute Walk and the Timed Up and Go test, and underwent a maximal graded cycle ergometer exercise test with measurement of peak oxygen uptake (VO2peak) to measure functional capacity. The mean time for completion of the Timed Up and Go test was 6.1 ± 1.7 seconds and the average distance traveled during the 6-Minute Walk was 459 ± 119 meters. Peak oxygen uptake was 24.7 ± 8.6 ml.kg.−1min−1, with a peak respiratory exchange ratio of ≥ 1.1 in all patients, suggesting a maximal effort. The patients attained a peak heart rate of 147 ± 27 beats per minute (89% ± 12% of the predicted maximal heart rate) and a peak workload of 152 ± 50 watts during the cycle ergometer test. Pearson Product-Moment Correlations between the standardized scores on the 3 tests were evaluated, and all tests correlated significantly (p ≤ 0.05) with each other. There was an inverse, moderate correlation between the 6-Minute Walk and the Timed Up and Go test (r ≡ −0.55), suggesting that these tests measure different attributes of physical function. When compared with VO2peak, the Timed Up and Go correlated highly, but inversely (r ≡ 0.71), while the 6-Minute Walk correlated only modestly (r ≡ 0.40). A linear regression procedure was performed with VO2peak as the dependent variable and the 6-Minute Walk and the Timed Up and Go as the independent variables. The Timed Up and Go was the only significant predictor of the VO2peak (β ≡ −3.574, constant ≡ 46.5; p ≤ 0.001), with an adjusted R square of 0.47 and standard error of the estimate of 0.47. These results suggest that muscle strength and/or motor function are important determinants of functional capacity in patients with Parkinson's Disease. Conclusion: The Timed Up and Go Test is a good indicator of functional capacity in patients with Parkinson's Disease and may be preferable to the 6-Minute Walk in these patients. Further work evaluating the ability of these tests to reflect changes in functional capacity is needed.

Effects of marked hyperthermia with and without dehydration on VO(2) kinetics during intense exercise.

This study determined whether marked hyperthermia alone or in combination with dehydration reduces the initial rate of rise in O(2) consumption (VO(2) on-kinetics) and the maximal rate of O(2) uptake (VO(2 max)) during intense cycling exercise. Six endurance-trained male cyclists completed four maximal cycle ergometer exercise tests (402 +/- 4 W) when euhydrated or dehydrated (4% body wt) with normal (starting esophageal temperature, 37.5 +/- 0.2 degrees C; mean skin temperature, approximately 31 degrees C) or elevated (+1 and +6 degrees C, respectively) thermal strain. In the euhydrated and normal condition, subjects reached VO(2 max) (4.7 +/- 0.2 l/min) in 228 +/- 34 s, with a mean response time of 42 +/- 2 s, and fatigued after 353 +/- 39 s. Hyperthermia alone or in combination with dehydration reduced mean response time (17-23%), VO(2 max) (16%), and performance time (51-53%) (all P < 0.01) but did not alter the absolute response time (i.e., the time to reach 63% response in the control trial, 3.2 +/- 0.1 l/min, 42 s). Reduction in VO(2 max) was accompanied by proportional decline in O(2) pulse and significantly elevated maximal heart rate (195 vs. 190 beats/min for hyperthermia vs. normal). Preventing hyperthermia in dehydrated subjects restored VO(2 max) and performance time by 65 and 50%, respectively. These results demonstrate that impaired high-intensity exercise performance with marked skin and internal body hyperthermia alone or in combination with dehydration is not associated with a diminished rate of rise in VO(2) but decreased VO(2 max).

Cardiac adverse effects and acute exercise in elderly subjects.

Cardiac arrhythmias, ST segment depressions and other cardiac adverse effects are occasionally seen in relation to physical exercise in elderly people. However, the magnitude, quality, and time-dependence of these events need to be clarified. During voluntary maximal cycle ergometer exercise (CEE), immediate cardiac disturbances as a reason for exercise termination were registered in a sample of 75-year-old men and women (N=203) (population group, PG). Any referrals to hospital following cardiac incidents within 24 hours post-CEE were obtained from patient records. Ambulatory ECG was recorded 24 hours before and after CEE in 23 elderly subjects (12 men, 11 women) capable of maximal effort (Holter group, HG). In the PG, 23.4% of the men and 6.4% of the women had to terminate CEE because of cardiac disturbances. One subject was referred to hospital because of exercise-induced atrial fibrillation. In the HG, no long-lasting effect of exercise on the occurrence of cardiac disturbances was found in elderly subjects capable of maximal effort.

Effect of brief maximal exercise on circulating levels of interleukin-12.

Interleukin-12 (IL-12) is a cytokine that was originally identified as natural killer cell stimulatory factor. It induces the activity of T-helper 1 (Th1) cells and exhibits strong anti-tumor activity. In this study, we studied the effects of brief anaerobic maximal exercise on circulating levels of IL-12. Six healthy males [mean (SD) 25.2 (2.6) years] performed a modified Wingate test exercise (resistance 0.075 kg/kg of body mass). The exercise consisted of five bouts of maximal cycling for 10 s, with rest intervals of 50 s between them. Blood samples were taken before, immediately after, 30 min after, 60 min after and 120 min after the exercise. Plasma concentrations of IL-12 were measured using an enzyme-linked immunosorbent assay. Data were corrected for hemoglobin and hematocrit measurements. Plasma concentrations of IL-12 averaged [mean (SD)] 234.2 (40.9) pg/ml before, 305.2 (62.1) pg/ml immediately after, 202.8 (24.2) pg/ml 30 min after, 239.7 (35.1) pg/ml 60 min after, and 199.6 (49.2) pg/ml 120 min after the exercise. We showed that plasma concentrations of IL-12 increased significantly immediately after brief anaerobic maximal cycle ergometer exercise (P < 0.01).

The Na(+)-K(+)-ATPase alpha2 gene and trainability of cardiorespiratory endurance: the HERITAGE family study.

The Na(+)-K(+)-ATPase plays an important role in the maintenance of electrolyte balance in the working muscle and thus may contribute to endurance performance. This study aimed to investigate the associations between genetic variants at the Na(+)-K(+)-ATPase alpha2 locus and the response (Delta) of maximal oxygen consumption (VO(2 max)) and maximal power output (W(max)) to 20 wk of endurance training in 472 sedentary Caucasian subjects from 99 families. VO(2 max) and W(max) were measured during two maximal cycle ergometer exercise tests before and again after the training program, and restriction fragment length polymorphisms at the Na(+)-K(+)-ATPase alpha2 (exons 1 and 21-22 with Bgl II) gene were typed. Sibling-pair linkage analysis revealed marginal evidence for linkage between the alpha2 haplotype and DeltaVO(2 max) (P = 0.054) and stronger linkages between the alpha2 exon 21-22 marker (P = 0.005) and alpha2 haplotype (P = 0.003) and DeltaW(max). In the whole cohort, DeltaVO(2 max) in the 3.3-kb homozygotes of the exon 1 marker (n = 5) was 41% lower than in the 8.0/3.3-kb heterozygotes (n = 87) and 48% lower than in the 8.0-kb homozygotes (n = 380; P = 0.018, adjusted for age, gender, baseline VO(2 max), and body weight). Among offspring, 10.5/10.5-kb homozygotes (n = 14) of the exon 21-22 marker showed a 571 +/- 56 (SE) ml O(2)/min increase in VO(2 max), whereas the increases in the 10.5/4.3-kb (n = 93) and 4.3/4.3-kb (n = 187) genotypes were 442 +/- 22 and 410 +/- 15 ml O(2)/min, respectively (P = 0.017). These data suggest that genetic variation at the Na(+)-K(+)-ATPase alpha2 locus influences the trainability of VO(2 max) in sedentary Caucasian subjects.