Wyniki wyszukiwania - Biblioteka Nauki

1

Purine metabolism in the light of aerobic and anaerobic capacity of female boxers

100%

Domaszewska K. , Szewczyk P. , Krysciak J. , Michalak E. , Podgorski T.

Central European Journal of Sport Sciences and Medicine

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2020

|

tom 30

|

nr 2

2

Prediction of vo2max based on age, body mass, and resting heart rate

100%

Rexhepi A. M. , Brestovci B.

Human Movement

|

2014

|

tom 15

|

nr 1

56-59

EN

Purpose. The aim of the present study was to develop a non-exercise regression model for predicting maximal oxygen uptake (VO2max) using age, body mass, and resting heart rate as predictor variables. Methods. The VO2max of 1502 active football players aged 16-35 years was measured using the Astrand Bike Test. The obtained data were analyzed by calculating basic statistical parameters and performing correlation and regression analysis. Results. The results of regression analysis indicated that all three independent variables could significantly (p = 0.000) predict the VO2max of the studied athletes. Measured VO2max showed significant correlation (0.688) with predicted VO2max. Student’s paired samples t test indicated no significant differences between measured VO2max and predicted VO2max (p = 0.782). Conclusions. The results suggest that the nonexercise variables of age, body mass, and resting heart rate, may significantly predict the endurance abilities of athletes (VO2max).

3

MODELING THE TOTAL ENERGY COSTS OF RESISTANCE EXERCISE: A WORK IN PROGRESS

100%

Scott C. B. , Reis V. M.

Central European Journal of Sport Sciences and Medicine

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2016

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tom 14

|

nr 2

5 - 12

EN

We present an aerobic and anaerobic, exercise and recovery energy cost model of intermittent energy costs utilizing task (work, Joules) as opposed to rate (per minute) measurements. Low to moderate intensity steady state exercise energy costs are typically portrayed as the volumetric rate at which oxygen is consumed (VO2 L min–1), where a proportionate upward climbing linear relationship is profiled with an increasing power output; add to this the concept of the anaerobic threshold and energy costs increase with more intense aerobic exercise in disproportion to VO2 L min–1 measurements. As a per task function, intermittent work and recovery bouts contain a combined estimate of total costs, that is as kJ or kcal (not kJ.min-1 or kcal.min-1). Adopting this approach to describe single and multiple sets of resistance training, the model that emerges for intermittent resistance exercise portrays linearity between equivalent work and total energy costs that differs proportionately among conditions – “continuous” muscular endurance vs. Intermittent higher load strength work, moderately paced vs. slower and faster conditions, smaller vs. larger working muscle masses and failure (fatigue) vs. non-failure states. Moreover, per kcal (or kJ) of total energy costs, work (J) is more inefficient with a greater load and lower repetition number as opposed to lower resistance with an increased number of repetitions. The concept of energy costs Rusing disproportionately with increased or prolonged work does not appear to apply to resistance exercise.

4

Aerobic and Anaerobic Energy During Resistance Exercise at 80% 1RM

100%

Vianna J. , Lima J. , Saavedra F. , Reis V.

Journal of Human Kinetics

|

2011

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tom 29A

|

nr Special Issue

69-74

EN

The present study investigated the accumulated oxygen deficit (AOD) method to assess the energy cost in resistance exercises (RE). The aim of the study was to evaluate the aerobic and anaerobic energy release during resistance exercises performed at 80% 1-RM in four exercises (half squat, bench press, triceps extension and lat pull down), as well as the accuracy of its estimation. The sample comprised 14 men (age = 26.6 ± 4.9 years; height = 177.7 ± 0.1 cm; body mass = 79.0 ± 11.1 kg; and estimated fat mass = 10.5 ± 4.6%). Test and re-test of 1-RM were applied to every exercise. Low-intensity bouts at 12, 16, 20, and 24% of 1-RM were conducted. Energy cost was then extrapolated to 80% 1-RM exhaustive bout and relative energy contribution were assessed. By utilizing the AOD method, the results of the present study suggest a great proportion of anaerobic metabolism during exercise at 80% 1-RM in the four RE that were analyzed: Bench press = 77,66±6,95%; Half squat = 87,44±6,45%; Triceps extension = 63,91±9,22%; Lat pull down = 71,99±13,73 %. The results of the present study suggest that AOD during resistance exercises presents a pattern that does not match the reports in the literature for other types of exercise. The accuracy of the total energy demand estimation at 80% 1-RM was acceptable in the Bench press, in the Triceps extension and in the Lat pull down, but no in the Half squat. More studies are warranted to investigate the validity of this method in resistance exercise.

5

Can Energy Cost During Low-Intensity Resistance Exercise be Predicted by the OMNI-RES Scale?

100%

Vianna J. , Reis V. , Saavedra F. , Damasceno V. , Silva S. , Goss F.

Journal of Human Kinetics

|

2011

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tom 29A

|

nr Special Issue

75-82

EN

The aim of the present study was to assess the precision of the OMNI-RES scale to predict energy cost (EC) at low intensity in four resistance exercises (RE). 17 male recreational body builders (age = 26.6 ± 4.9 years; height = 177.7 ± 0.1 cm; body weight = 79.0 ± 11.1 kg and percent body fat = 10.5 ± 4.6%) served as subjects. Initially tests to determine 1RM for four resistance exercises (bench press, half squat, lat pull down and triceps extension) were administered. Subjects also performed resistance exercise at 12, 16, 20, and 24% of 1RM at a rate of 40 bpm until volitional exhaustion. Oxygen uptake (VO2) and rate of perceived exertion (RPE) using the OMNI-RES were obtained during and after all RE. EC was calculated using VO2 and the caloric values of VO2 for non-protein RER. Regression analyses were performed for every RE, using EC as the dependent and RPE as the predictor variable. The triceps extension, lat pull down and bench press, RPE correlated strongly with EC (R > 0.97) and predicted EC with a error of less than 0.2 kcal.min-1. In conclusion, RPE using the OMNI-RES scale can be considered as an accurate indicator of EC in the bench press, lat pull down and triceps extension performed by recreational bodybuilders, provided lower intensities are used (up to 24% of 1-RM) and provided each set of exercise is performed for the maximal sustainable duration. It would be interesting in future studies to consider having the subjects exercise at low intensities for longer durations than those in the present study.

6

Game Intensity Analysis of Elite Adolescent Ice Hockey Players

100%

Stanula A. , Roczniok R.

Journal of Human Kinetics

|

2014

|

tom 44

|

nr 1

211-221

EN

The purpose of this study was to determine ice-hockey players’ playing intensity based on their heart rates (HRs) recorded during a game and on the outcomes of an incremental maximum oxygen uptake test. Twenty ice-hockey players, members of the Polish junior national team (U18), performed an incremental test to assess their maximal oxygen uptake (V̇ O2max) in the two week’s period preceding 5 games they played at the World Championships. Players’ HRs at the first and second ventilatory thresholds obtained during the test were utilized to determine intensity zones (low, moderate, and high) that were subsequently used to classify HR values recorded during each of the games. For individual intensity zones, the following HRs expressed as mean values and as percentages of the maximal heart rate (HRmax) were obtained: forwards 148-158 b⋅min-1 (79.5-84.8% HRmax), 159-178 b⋅min-1 (85.4-95.6% HRmax), 179-186 b⋅min-1 (96.1-100.0% HRmax); defensemen 149-153 b⋅min-1 (80.0-82.1% HRmax), 154-175 b⋅min-1 (82.6- 94.0% HRmax), 176-186 b⋅min-1 (94.5-100.0% HRmax). The amount of time the forwards and defensemen spent in the three intensity zones expressed as percentages of the total time of the game were: 54.91 vs. 55.62% (low), 26.40 vs. 22.38% (moderate) and 18.68 vs. 22.00% (high). The forwards spent more time in the low intensity zone than the defensemen, however, the difference was not statistically significant. The results of the study indicate that using aerobic and anaerobic metabolism variables to determine intensity zones can significantly improve the reliability of evaluation of the physiological demands of the game, and can be a useful tool for coaches in managing the training process.

7

Oxygen Uptake and Heart Rate Kinetics after Different Types of Resistance Exercise

100%

Vianna J. M. , Werneck F. Z. , Coelho E. F. , Damasceno V. O. , Reis V. M.

Journal of Human Kinetics

|

2014

|

tom 42

|

nr 1

235-244

EN

Oxygen uptake (VO2) and heart rate (HR) kinetics after exercise are important indicators of fitness and cardiovascular health. However, these variables have been little investigated in resistance exercise (RE). The current study compared post-exercise kinetics of VO2 and the HR among different types of REs. The study included 14 males (age: 26.5±5.4 years, body mass: 80.1±11.4 kg, body height: 1.77±0.07 m, fat content: 11.3±4.6%) with RE experience. Dynamic muscle strength was measured using one repetition maximum (1RM) with regard to the half-squat, bench press, pull-down, and triceps pushdown exercises. The participants performed a maximum number of repetitions at 80% of 1RM for each exercise, separated by a recovery period of 60 minutes. VO2 was measured using ergospirometry. VO2 and HR kinetics were assessed using the time constant of the recovery curves, and excess oxygen consumption (EPOC) was calculated afterward. Significant differences were not observed across the exercises with regard to VO2 kinetics. However, the half-squat exercise elicited a greater EPOC than the bench press and triceps pushdown exercises (p<.05). HR kinetics was slower for the half-squat exercise than for the other exercises (p<.05). These findings confirm that the type of RE influences both the cardiac autonomic response post-exercise and EPOC, but not VO2 kinetics

8

Uptake of molecular oxygen by Co(II) chelates with peptides in an aqueous colution : Part XI : Stereoselective properties of oxygenated diastereoisomeric dipeptide systems

100%

Kufelnicki A. , Świątek M.

Polish Journal of Chemistry

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1999

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tom vol. 73 nr 4

579-591

EN

The reaction of oxygen uptake by Co(II) complexes with a group of diastereoisimetric dipeptides, consisting of alanine and leucine in various chiral forms, has been studied in an aqueous solution. The structure of the bridging moiety has been discussed on the basis of spectroscopic results (UV, Vis, near IR, CD, ESR). The effect of stereoselectivity has been confirmed by studies of reversibility of oxygenation. Comparative ESR measurements were done for mixed complexes with imidazole as N-base in the axial position. All of the results were compared with that for glycine dipeptides (containing only one asymmetric atom).

9

Non-linear relationship between oxygen uptake and power output in the Astrand nomogram - old data revisited

100%

Zoladz J. A. , Szkutnik Z. , Majerczak J. , Duda K. , Pedersen P. K.

Journal of Physiology and Pharmacology

|

2007

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tom 58

|

nr 2

EN

For the last decade there have been considerable discussion concerning the linearity / non-linearity of the oxygen uptake (O2) - power output (W) relationship with strong experimental evidence of non-linearity provided mainly by breath-by-breath measurements. In this study, we attempted to answer the question whether the O2 - W relationship in the Åstrand nomogram, as presented in the Textbook of Work Physiology, P.-O. Åstrand et al. (2003), page 281, based on the Douglas bag method, is indeed linear, as stated by the authors before, or if a change point in O2, described by Zoladz et al. (1998) Eur J Appl Physiol 78: 369-377, can possibly be detected in those data. The O2 - W data were taken from the Åstrand nomogram referenced above and from the Table 9.5 on page 282 in the same reference and tested for the presence of the change point in O2, using our two-phase model (see the reference above). In the first phase, a linear O2 - W relationship was assumed, whereas in the second one (above the so-called change point) an additional increase in O2 above the values expected from the linear model was allowed. It was found that in the data taken from the Åstrand nomogram (data for men), as well as in the data taken from the Table 9.5, statistically significant change points in O2 were present at the power output of 150 W. The documentation of the presence of a change point in the O2 - W relationship in the Åstrand data provides further evidence for the existence of a non-linearity in the O2 - W relationship in incremental exercise tests of humans, also in O2 data based upon the Douglas bag method.

10

Effect of exercise intensity on the slow component of oxygen uptake in decremental work load exercise

100%

Yano T. , Yunoki T. , Matsuura R. , Ogata H.

Journal of Physiology and Pharmacology

|

2004

|

tom 55

|

nr 2

EN

The paper sought to determine the exercise intensity where the slow component of oxygen uptake (o2) first appears in decremental work load exercise (DLE). Incremental work load exercise (ILE) was performed with an increment rate of 15 watts (W) per minute. In DLE, power outputs were decreased by 15 W per minute, from 120 (DLE120), 160 (DLE160), 200 (DLE200) and 240 (DLE240) W, respectively. The slopes of o2 against the power output were obtained in the lower section from 0 to 50 W in all DLEs, and in the upper section from 80 to 120 W in DLE160 and from 100 to 150 W in DLE200 and DLE240. The power output at exhaustion in ILE was 274 ± 20 W. The power output at the ventilatory threshold (VT) obtained in ILE was 167 ± 22 W. The initial power output in DLE160 was near the power output at VT. The slopes obtained in the upper sections were 11.4 ± 0.9 ml • min-1 • W-1 in DLE160, 12.8 ± 0.8 ml • min-1 • W-1 in DLE200, and 14.8 ± 1.1 ml • min-1 • W-1 in DLE240. The slope obtained in DLE120 was 10.9 ± 0.6 ml • min-1. There were no differences in slope between the upper and lower sections in DLE160 but there were significant differences in slopes between the upper and lower sections in DLE200 and DLE240. Thus, the slow component, which could be observed as a steeper slope in DLE, began to increase when the initial power output in DLE was near to VT.

11

Microbial efficiency in a meromictic reservoir

88%

Mazurkiewicz-Boroń G. , Bednarz T. , Wilk-Woźniak E.

Oceanological and Hydrobiological Studies

|

2008

|

tom Vol. 37, No.2

3-19

EN

Indices of microbial efficiency (expressed as oxygen consumption and carbon dioxide release) were determined in the water column of the meromictic Piaseczno Reservoir (in an opencast sulphur mine), which is rich in sulphur compounds. Phytoplankton abundances were low in both the mixolimnion (up to 15 m depth) and monimolimnion (below 15 m depth). In summer and winter, carbon dioxide release was 3-fold and 5-fold higher, respectively, in the monimolimnion than in the mixolimnion. Laboratory enrichments of the sulphur substrate of the water resulted in a decrease in oxygen consumption rate of by about 42% in mixolimnion samples, and in the carbon dioxide release rate by about 69% in monimolimnion samples. Water temperature, pH and bivalent ion contents were of major importance in shaping the microbial metabolic efficiency in the mixolimnion, whilst in the monimolimnion these elationships were not evident.

12

The Effect of Climbing Ability and Slope Inclination on Vertical Foot Loading Using a Novel Force Sensor Instrumentation System

88%

Baláš J. , Panáčková M. , Jandová S. , Martin A. J. , Strejcová B. , Vomáčko L. , Charousek J. , Cochrane D. J. , Hamlin M. , Draper N.

Journal of Human Kinetics

|

2014

|

tom 44

|

nr 1

75-81

EN

The aim of the study was to assess the effects of climbing ability and slope inclination on vertical loading both in terms the forces involved and physiological responses. Five novice and six intermediate female climbers completed a climbing route at three slope inclinations (85°, 90°, and 98°). The vertical loading during the climb was assessed by force-time integral using a Novel Pedar-X insole and physiological responses via oxygen uptake and heart rate. The novice climbers had a significantly lower (p < 0.05) vertical loading on foot holds and higher oxygen uptake and heart rate compared to intermediate climbers. A significant negative correlation was identified between the force-time integral and oxygen uptake (R = -0.72), and with heart rate (R = -0.64), respectively. The time-force integral decreased across the ascents with increasing slope inclination (p < 0.001). The results indicate that more advanced ability climbers make greater use of foot holds, with associated lowering in physiological response (oxygen uptake and heart rate) across all slope inclinations.

13

Development and Validation of an Automated Step Ergometer

88%

C. de Sousa M. d. S. , Aniceto R. R. , Neto G. R. , T. de Araújo R. C. , C. de Sousa J. B. , Costa J. A. D. , Pellegrinotti I. L.

Journal of Human Kinetics

|

2014

|

tom 43

|

nr 1

113-124

EN

Laboratory ergometers have high costs, becoming inaccessible for most of the population, hence, it is imperative to develop affordable devices making evaluations like cardiorespiratory fitness feasible and easier. The objective of this study was to develop and validate an Automated Step Ergometer (ASE), adjusted according to the height of the subject, for predicting VO2max through a progressive test. The development process was comprised by three steps, the theoretical part, the prototype assembly and further validation. The ASE consists in an elevating platform that makes the step at a higher or lower level as required for testing. The ASE validation was obtained by comparing the values of predicted VO2max (equation) and direct gas analysis on the prototype and on a, treadmill. For the validation process 167 subjects with average age of 31.24 ± 14.38 years, of both genders and different degrees of cardiorespiratory fitness, were randomized and divided by gender and training condition, into untrained (n=106), active (n=24) and trained (n=37) subjects. Each participant performed a progressive test on which the ASE started at the same height (20 cm) for all. Then, according to the subject’s height, it varied to a maximum of 45 cm. Time in each stage and rhythm was chosen in accordance with training condition from lowest to highest (60-180 s; 116-160 bpm, respectively). Data was compared with the student’s t test and ANOVA; correlations were tested with Pearson’s r. The value of α was set at 0.05. No differences were found between the predicted VO2max and the direct gas analysis VO2max, nor between the ASE and treadmill VO2max (p= 0.365) with high correlation between ergometers (r= 0.974). The values for repeatability, reproducibility, and reliability of male and female groups measures were, respectively, 4.08 and 5.02; 0.50 and 1.11; 4.11 and 5.15. The values of internal consistency (Cronbach’s alpha) among measures were all >0.90. It was verified that the ASE prototype was appropriate for a step test, provided valid measures of VO2max and could therefore, be used as an ergometer to measure cardiorespiratory fitness.

14

Myosin heavy chain composition in the vastus lateralis muscle in relation to oxygen uptake and heart rate during cycling in humans

75%

Majerczak J. , Nieckarz Z. , Karasinski J. , Zoladz J. A.

Journal of Physiology and Pharmacology

|

2014

|

tom 65

|

nr 2

15

Rating of Perceived Exertion and Physiological Responses in Water-Based Exercise

75%

Santana Pinto S. , Lima Alberton C. , Zaffari P. , Lusa Cadore E. , Kanitz A. C. , Veiga Liedtke G. , Peikriszwili Tartaruga M. , Martins Kruel L. F.

Journal of Human Kinetics

|

2015

|

tom 49

|

nr 1

99-108

EN

The aim of the present study was to relate the overall rating of perceived exertion (RPE-overall) with cardiorespiratory and neuromuscular variables during stationary running with the elbow flexion/extension performed with water-floating equipment. The sample consisted of eleven women that performed the water-based exercise at submaximal cadences. The heart rate, oxygen uptake, ventilation, and electromyographic signal (EMG) from biceps brachii (%EMG BB), triceps brachii (%EMG TB), biceps femoris (%EMG BF) and rectus femoris (%EMG RF) muscles were measured during the exercise, and the overall RPE was measured immediately following its completion. The Pearson product-moment linear correlation was used to investigate associations between the variables analyzed in the present study. Significant relationships were observed between the RPE-overall and all the cardiorespiratory variables, with the r values ranging from 0.60 to 0.70 (p<0.05). In addition, the RPE-overall showed a significant (p<0.05) relationship with %EMG BB (r=0.55) and %EMG BF (r=0.50). These results suggest an association between the RPE-overall with all cardiorespiratory and two neuromuscular variables during the execution of a water-based aerobic exercise using water-floating equipment.

16

A Physiological and Kinematic Comparison of two Different Lean Back Positions During Stationary Rowing on a Concept II Machine

75%

Bell G. , Bennett J. , Reynolds W. , Syrotuik D. , Gervais P.

Journal of Human Kinetics

|

2013

|

tom 37

|

nr 1

99-108

EN

This study compared two different body positions at the finish of a stroke during stationary rowing exercise on physiological and kinematic measurements. Nine male and five female rowers volunteered for the study: mean age (± SD), body height and body mass were 27 ±9 yrs, 180.5 ±12.3 cm and 81.2 ±14.2 kg. The two body positions at the finish were controlled at an upright posture or a novel greater lean back position. All subjects completed 3 different experimental trials on a Concept IID rowing machine at 3 different exercise intensities and comparisons were made between the lean back position at the same stroke rate and the same power output as the upright trial. Power output, heart rate, oxygen uptake, energy expenditure and % efficiency were higher (p<0.05) with the greater lean back position at the same stroke rate compared to all other conditions. Range of motion at the hip, ankle, and elbow and the handle velocity and distance moved were greater (p<0.05) with the lean back position. In conclusion, a greater lean back posture at the finish during stationary rowing produces a higher power output and improved efficiency at the same stroke rate but at an elevated physiological cost compared to a more upright position. Despite the higher energy expenditure, the relative gain in power output and efficiency with no negative kinematic changes suggests that a greater lean back position at the finish will enhance performance during stationary rowing exercise.

17

Nitric oxide is involved in the mediation of gastric blood flow and tissue oxygenation

75%

Gustaw P. , Pawlik W. W. , Czarnobilski K. , Sendur R. , Konturek S. J.

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nr 3

18

Involvement of central and peripheral histamine H3 receptors in the control of the vascular tone and oxygen uptake in the mesenteric circulation of the rat

75%

Obuchowicz R. , Pawlik M. W. , Brzozowski T. , Konturek S. J. , Pawlik W. W.

Journal of Physiology and Pharmacology

|

2004

|

tom 55

|

nr 1,2

EN

Data concerning cardiovascular effects of peripherally and centrally located histamine H3 receptor stimulation are contradictory, and despite excessive studies their role in the control of the cardiovascular function have not been cleared yet. Effect of histamine H3 receptors activation have been attributed to modulation of sympathetic system activity but exact role of peripherally and centrally located histamine H3 receptors stimulation in the modulation of vascular tone of the mesentery and intestinal metabolism remains unexplored. Aim of the present study was to evaluate the role of centrally and peripherally located histamine H3 receptors in the modulation of vascular tone of the mesentery and metabolic activity of intestinal tissue. In anesthetized rats total mesenteric blood flow (MBF), mucosal intestinal blood flow (LDBF), intestinal oxygen uptake (VO2) and arterial pressure (AP) were determined. Intestinal arterial conductance (C) was also calculated. Administration of the selective histamine H3 receptor agonist imetit (10 µmol/kg i.a) evoked marked changes in hemodynamic and metabolic parameters; MBF, LDBF, C and VO2 were significantly increased, whereas AP was significantly decreased. Pretreatment with histamine H3 receptor antagonist clobenpropit (4 µmol/kg i.a.) abolished imetit-induced circulatory and oxygen uptake responses. Clobenpropit (4 µmol/kg i.a.) alone failed to affect the MBF, LDBF, AP, C and VO2 values. Central administration of imetit (0.1 µmol i.c.v.) markedly increased AP and decreased MBF, LDBF, C and VO2. Pretreatment with histamine H3 receptor antagonist clobenpropit (0,4 µmol i.c.v.) diminished circulatory and metabolic responses to centrally injected imetit. Central histamine H3 receptors blockade by clobenpropit evoked no significant changes in the mesenteric arterial and mucosal microcirculatory blood flow, intestinal metabolism and mean arterial pressure. We conclude that, peripheral histamine H3 receptors when stimulated decreases vasoconstrictory tone of the mesenteric artery and precapillary structures and evokes increase of intestinal oxygen uptake. This might be in part due to inhibition of sympathetic postganglionic fibers vasopressor activity. Central histamine H3 receptor stimulation activates vasoconstrictory sympathetic adrenergic system with possible involvement of other, presumably non-histaminergic receptors system. At basal conditions neither central nor peripheral histamine H3 receptors are involved in the control of mesenteric macro - and microcirculation and intestinal oxygen consumption.

19

Physiological background of the change point in VO2 and the slow component of oxygen uptake kinetics

75%

Zoladz J. A. , Korzeniewski B.

Journal of Physiology and Pharmacology

|

2001

|

tom 52

|

nr 2

20

High content of MyHC II in vastus lateralis is accompanied by higher VO2/power output ratio during moderate intensity cycling performed both at low and at high pedalling rates

75%

Majerczak J. , Szkutnik Z. , Karasinski J. , Duda K. , Kolodziejski L. , Zoladz J. A.

Journal of Physiology and Pharmacology

|

2006

|

tom 57

|

nr 2

EN

The aim of this study was to examine the relationship between the content of various types of myosin heavy chain isoforms (MyHC) in the vastus lateralis muscle and pulmonary oxygen uptake during moderate power output incremental exercise, performed at low and at high pedalling rates. Twenty one male subjects (mean ± SD) aged 24.1 ± 2.8 years; body mass 72.9 ± 7.2 kg; height 179.1 ± 4.8 cm; BMI 22.69 ± 1.89 kg . m-2; VO2max 50.6 ± 5.3 ml . kg . min-1, participated in this study. On separate days, they performed two incremental exercise tests at 60 rev . min-1 and at 120 rev . min-1, until exhaustion. Gas exchange variables were measured continuously breath by breath. Blood samples were taken for measurements of plasma lactate concentration prior to the exercise test and at the end of each step of the incremental exercise. Muscle biopsies were taken from the vastus lateralis muscle, using Bergström needle, and they were analysed for the content of MyHC I and MyHC II using SDS - PAGE and two groups (n=7, each) were selected: group H with the highest content of MyHC II (60.7 % ± 10.5 %) and group L with the lowest content of MyHC II (27.6 % ± 6.1 %). We have found that during incremental exercise at the power output between 30 - 120 W, performed at 60 rev . min-1, oxygen uptake in the group H was significantly greater than in the group L (ANCOVA, p=0.003, upward shift of the intercept in VO2 / power output relationship). During cycling at the same power output but at 120 rev . min-1, the oxygen uptake was also higher in the group H, when compared to the group L (i.e. upward shift of the intercept in VO2 / power output relationship, ANCOVA, p=0.002). Moreover, the increase in pedalling rate from 60 to 120 rev . min-1 was accompanied by a significantly higher increase of oxygen cost of cycling and by a significantly higher plasma lactate concentration in subjects from group H. We concluded that the muscle mechanical efficiency, expressed by the VO2 / PO ratio, during cycling in the range of power outputs 30 - 120 W, performed at 60 as well as 120 rev . min-1, is significantly lower in the individuals with the highest content of MyHC II, when compared to the individuals with the lowest content of MyHC II in the vastus lateralis.