Maximal Oxygen Uptake Values Research Articles

The efficacy of the self-paced V̇O2max test to measure maximal oxygen uptake in treadmill running

The novel self-paced, cycle-based maximal oxygen uptake (V̇O2max) test (SPV) has been shown to produce higher V̇O2max values than standard graded exercise test (GXT) protocols. This study sought to ascertain whether these observations would also be apparent in a self-paced, treadmill-based test design. Fourteen trained male runners performed a standard GXT on a motorised treadmill and a self-paced V̇O2max test on a nonmotorised treadmill in a counter-balanced design. The GXT included a plateau verification and was designed to last between 8 and 12 min. The self-paced test included 5 × 2 min stages and allowed participants to set their own running speed based on fixed increments in rating of perceived exertion. Significantly higher V̇O2max values (t[13] = 3.71, p = 0.003) were achieved in the self-paced test (64.4 ± 7.3 mL · kg(-1) · min(-1)) compared with the GXT (61.3 ± 7.3 mL · kg(-1) · min(-1)), and 13 of the 14 participants achieved the same or higher V̇O2max values in the self-paced test. Higher (p = 0.01) maximum heart rates were observed in the GXT (191 ± 10 beats · min(-1) vs. 187 ± 7 beats · min(-1)), but no differences were observed in any other recorded variables. The self-paced V̇O2max test may provide a more valid means of measuring V̇O2max than the GXT and suggests that a V̇O2 plateau during a GXT does not always signify achievement of a definitive V̇O2max. These results provide further support that self-paced V̇O2max testing produces higher values for maximal oxygen uptake.

Anthropometric and cardiovascular characteristics of young elite male handball players according to playing positions

The purpose of the present study was to examine the anthropometric parameters and cardiopulmonary functions of young handball players in different playing positions. 15 male handball players from first division (mean age: 16.06±0.63 yrs) participated in our research who were divided by their playing positions. First anthropometric parameters, body composition and pulmonary functions in rest were measured. Then physiological changes of the players were tested with Bruce protocol. We found that wings differed the most in morphological characteristics from other players. We did not find significant differences in pulmonary functions among positions. The highest values of Tidal volume in the vita maxima test were found in pivots (2.82±0.15 l) which is significantly higher than Tidal volume of goalkeepers (p=0.006). The highest mean value of maximal oxygen uptake was recorded (73.93±9.41 ml/kg/min) in wings. Altogether in our study important differences were seen in physique and in performance also among young handball players.

Differences in the direction of effort adaptation between mountain bikers and road cyclists

PurposeDifferent forms of cycling require the use of different abilities and skills. The aim of this paper was to attempt to identify differences in the directions and dynamics of the body’s adaption to training in road (ROAD) and mountain (MTB) cyclists.MethodsResearch was performed on a group of competitive road (<i>n</i> = 25) and mountain (<i>n</i> = 25) cyclists, mean age 16.96 ± 0.78 years presenting maximal oxygen uptake values of 4.45 ± 0.47 L/min-1. Body composition and physiological and biochemical parameters at rest, during exercise, and during restitution (cool down) were determined. Exercise was performed on a cycle ergometer in the form of a progressive load test. Analysis of the results included cluster analysis and basic statistical methods.ResultsCluster analysis indicated that the amount of work performed during the progressive load test was a universal indicator of physical fitness. The level of base excess (BE) in the 3rd min of restitution had a large influence on the remaining parameters in both groups. Training adaptation in MTB were manifested through increased values of maximum heart rate, blood oxygen saturation, oxygen partial pressure, and lactate and BE levels in the blood, as well as a reduction in blood pH and body mass. Conversely, in ROAD, adaptation to effort was evidenced by increased maximum values of oxygen uptake, minute ventilation, cardiac output and the rate of carbon dioxide elimination as well as an increase in hematocrit count and lean body mass.ConclusionsAdaptation to training by road cyclists is primarily evident in the development of aerobic capacity. Mountain biking induces adaptive changes in the development of anaerobic capacity by increasing the buffer capacity of the blood and muscles, as well as the development of the oxygen transportation system.

Exercise efficiency is reduced by mitochondrial uncoupling in the elderly

A reduction in exercise efficiency accompanies ageing in humans. Here we evaluated the impact of changes in the contractile-coupling and mitochondrial-coupling efficiencies on the reduction in exercise efficiency in the elderly. Nine adult (mean, 38.8 years old) and 40 elderly subjects (mean, 68.8 years old) performed a cycle ergometer test to measure O2 uptake and leg power output up to the aerobic limit ( ). Reduced leg power output per unit O2 uptake was reflected in a drop in delta efficiency (εD) from 0.27 ± 0.01 (mean ± SEM) in adults to 0.22 ± 0.01 in the elderly group. Similar declines with age were apparent for both the leg power output at and the ATP generation capacity (ATPmax) determined in vivo using (31)P magnetic resonance spectroscopy. These similar declines resulted in unchanged contractile-coupling efficiency values (εC) in the adult (0.50 ± 0.05) versus the elderly group (0.58 ± 0.04) and agreed with independent measures of muscle contractile-coupling efficiency in human quadriceps (0.5). The mitochondrial-coupling efficiency calculated from the ratio of delta to contractile-coupling efficiencies in the adults (εD/εC = 0.58 ± 0.08) corresponded to values for well-coupled mitochondria (0.6); however, εD/εC was significantly lower in the elderly subjects (0.44 ± 0.03). Conversion of ATPmax per mitochondrial volume (ATPmax/Vv[mt,f]) reported in these groups into thermodynamic units confirmed this drop in mitochondrial-coupling efficiency from 0.57 ± 0.08 in adults to 0.41 ± 0.03 in elderly subjects. Thus, two independent methods revealed that reduced mitochondrial-coupling efficiency was a key part of the drop in exercise efficiency in these elderly subjects and may be an important part of the loss of exercise performance with age.

Impact of obesity on exercise performance and pulmonary rehabilitation

While the impact of obesity on respiratory function has been extensively studied, and several definitive conclusions have emerged, its impact on exercise performance is complex, with the available data sometimes providing contradictory or inconclusive information. Based on the literature discussed, it appears that resting alterations in lung volumes and gas exchange become attenuated during exercise in the obese, while oxygen cost of breathing and dyspnoea are increased. Respiratory muscle function also seems to be impaired, such that inspiratory muscle strength is reduced and respiratory drive is increased. Furthermore, while there is no reduction in the absolute values of maximal oxygen uptake compared with normal-weight subjects, oxygen uptake at a given workload is increased and maximal workload is reduced in the obese, caused by increases in body mass and/or basal metabolic rate. To date, obesity has not been listed as an indication for pulmonary rehabilitation (PR), hence the reason why conclusive data on the impact of obesity per se on PR are lacking. The majority of evidence discussed is based on comparative data from obese versus normal-weight patients, with respiratory disorders currently established as indications for PR. The best evidence currently available regarding the impact of obesity on PR is for patients with chronic obstructive pulmonary disease (COPD); here, it appears that obesity per se has no negative impact on PR. Otherwise, there are no conclusive data on the impact of obesity on PR in respiratory disorders other than COPD, and this remains to be investigated in the future.

EVALUATION OF AEROBIC CAPACITY IN SOCCER PLAYERS: COMPARISON OF FIELD AND LABORATORY TESTS

The purpose of this study was to evaluate the maximal oxygen uptake ( · VO2max) values in soccer players as assessed by field and laboratory tests. Fourteen amateur soccer players (mean age: 21.9 ± 2.5) performed 2 maximal field tests: the Yo-Yo intermittent recovery test level 1 (YIRT), and the 20-m multi-stage shuttle run test (MST), as well as 1 maximal test on the treadmill with the Bruce treadmill test (BTRT) protocol. A portable telemetric ergospirometry device was used during all the tests to determine · VO2max. In addition, an estimated · VO2max value was calculated for players after all the tests. At the end of the study, no significant differences were found between field and laboratory tests in terms of measured · VO2max, HRmax and respiratory exchange ratio (RER) (p>0.05), whereas significant differences were found between field and laboratory tests in terms of estimated · VO2max (p<0.05). In addition, there were no significant differences between measured · VO2 and estimated · VO2max in BTRT, whereas significant differences were found between measured · VO2max and estimated · VO2max in both YIRT and MST. Finally, while there was a strong relationship between · VO2max and both MST and BTRT performance (distance covered), there was a moderate correlation between · VO2max and YIRT performance. This study results suggest that it is necessary to use ergospirometry to accurately estimate aerobic capacity in soccer players. In addition, both MST and YIRT could be used to determine HRmax of players, and MST has a strong relationship with · VO2max. Thus MST may also be a more favourable field-based assessment

Specific alterations of physiological parameters in competitive race walkers

Race walking is the technical and athletic expression of fast walking and it can be considered as a type of endurance performance. The purpose of this study was to examine whether 12 weeks of a specially designed training program results in the further training enhancement of endurance performance and the related physiological parameters in already well-trained race walkers competing at the national and international level. The investigation protocol consisted of determining the maximal oxygen uptake (VO2peak) and related gas exchange values using an automated cardiopulmonary exercise system and of determining blood lactate variables (aerobic threshold - LTAer and the maximal lactate steady state - MLSS) during walking with proper technique at 8, 10, 12 and 14 km·h-1 for 4 minutes without rest in between. Thereafter, the speed on the treadmill was increased by 0.5 km·h-1 every two minutes until exhaustion to determine VO2peak. After 12 weeks of a specially designed endurance training, statistically significant increases in VO2peak (61.8±8.5 mL·kg-1·min-1 pre vs. 66.9±9.5 mL·kg-1·min-1 post training; p<0.05) and blood lactate variables (VO2-LTAer and VO2-MLSS; p<0.05) were noted. The obtained results suggest that the applied training program can improve endurance and race performance in previously well trained race walkers.

The effects of periodized concurrent and aerobic training on oxidative stress parameters, endothelial function and immune response in sedentary male individuals of middle age

The vascular endothelium plays a key role in arterial wall homeostasis by preventing atherosclerotic plaque formation. A primary causal factor of endothelial dysfunction is the reactive oxygen species. Aerobic exercise is ascribed as an important adjuvant therapy in endothelium-dependent cardiovascular disease. However, little is known about the effects of concurrent (aerobic + strength) training on that. For a comparison of the effects of aerobic and concurrent physical training on endothelial function, oxidative stress parameters and the immunoinflammatory activity of monocytes/macrophages, 20 adult male volunteers of middle age were divided into a concurrent training (CT) programme group and an aerobic training group. The glutathione disulphide to glutathione ratio (GSSG/GSH) and plasma lipoperoxide (LPO) levels, as well as flow-mediated dilation (FMD), monocyte/macrophage functional activity (zymosan phagocytosis), body lipid profiles, aerobic capacity (maximal oxygen uptake) and strength parameters (one-repetition maximum test), were measured before and after the exercise training programmes. The CT exhibited reduced acute effects of exercise on the GSSG/GSH ratio, plasma LPO levels and zymosan phagocytosis. The CT also displayed improved lipid profiles, glycaemic control, maximal oxygen uptake and one-repetition maximum test values. In both the aerobic training and the CT, training improved the acute responses to exercise, as inferred from a decrease in the GSSG/GSH ratios. The aerobic sessions did not alter basal levels of plasma LPO or macrophage phagocytic activity but improved FMD values as well as lipid profiles and glycaemic control. In summary, both training programmes improve systemic redox status and antioxidant defences. However, the aerobic training was more efficient in improving FMD in the individuals studied.

Physiological Profiles of Elite Judo Athletes

To be successful in international competitions, judo athletes must achieve an excellent level of physical fitness and physical condition during training. This article reviews the physiological profiles of elite judo athletes from different sex, age and weight categories. Body fat is generally low for these athletes, except for the heavyweight competitors. In general, elite judo athletes presented higher upper body anaerobic power and capacity than non-elite athletes. Lower body dynamic strength seems to provide a distinction between elite and recreational judo players, but not high-level judo players competing for a spot on national teams. Even maximal isometric strength is not a discriminant variable among judo players. However, more studies focusing on isometric strength endurance are warranted. Although aerobic power and capacity are considered relevant to judo performance, the available data do not present differences among judo athletes from different competitive levels. Typical maximal oxygen uptake values are around 50-55 mL/kg/min for male and 40-45 mL/kg/min for female judo athletes. As for other variables, heavyweight competitors presented lower aerobic power values. The typical differences commonly observed between males and females in the general population are also seen in judo athletes when analysing anaerobic power and capacity, aerobic power, and maximal strength and power. However, further research is needed concerning the differences among the seven weight categories in which judo athletes compete.

Validation of Heart Rate Monitor-Based Predictions of Oxygen Uptake and Energy Expenditure

To validate VO2 and energy expenditure predictions by the Suunto heart rate (HR) system against a first principle gas analysis system, well-trained male (n = 10, age 29.8 +/- 4.3 years, VO2 65.9 +/- 9.7 ml x kg x min) and female (n = 7, 25.6 +/- 3.6 years, 57.0 +/- 4.2 ml x kg x min) runners completed a 2-stage incremental running test to establish submaximal and maximal oxygen uptake values. Metabolic cart values were used as the criterion measure of VO2 and energy expenditure (kJ) and compared with the predicted values from the Suunto software. The 3 levels of software analysis for the Suunto system were basic personal information (BI), BI + measured maximal HR (BIhr), and BIhr + measured VO2 (BIhr + v). Comparisons were analyzed using linear regression to determine the standard error of the estimate (SEE). Eight subjects repeated the trial within 7 days to determine reliability (typical error [TE]). The SEEs for oxygen consumption via BI, BIhr, and BIhr + v were 2.6, 2.8, and 2.6 ml.kg.min, respectively, with corresponding percent coefficient of variation (%CV) of 6.0, 6.5, and 6.0. The bias compared with the criterion VO2 decreased from -6.3 for BI, -2.5 for BIhr, to -0.9% for BIhr + v. The SEE of energy expenditure improved from BI (6.74 kJ) to BIhr (6.56) and BIhr + v (6.14) with corresponding %CV of 13.6, 12.2, and 12.7. The TE values for VO2 were approximately 0.60 ml x kg x min and approximately 2 kJ for energy expenditure. The %CV for VO2 and energy expenditure was approximately 1 to 4%. Although reliable, basic HR-based estimations of VO2 and energy expenditure from the Suunto system underestimated VO2 and energy expenditure by approximately 6 and 13%, respectively. However, estimation can be improved when maximal HR and VO2 values are added to the software analysis.

Validation of the Human Activity Profile in HIV-Positive Individuals on HAART

Objectives: This study tested the validity of the Human Activity Profile (HAP) in an HIV-positive population receiving highly active antiretroviral therapy (HAART). The HAP is a 94-item questionnaire for estimating functional capacity based on estimated metabolic equivalents for activities of daily living. Methods: Twenty-six HIV-positive participants (24 male, 2 female; age 46.0 ± 9.3 years) receiving HAART completed the HAP and an exercise protocol (Balke treadmill test). The HAP yields a maximal activity score (MAS) and adjusted activity score (AAS; MAS minus activities no longer performed). Twelve participants also completed another nonexercise questionnaire (NEx). Results: Mean maximal oxygen uptake values (VO2max) were normally distributed, similar to non–HIV-positive normative data (37.73 ± 6.95 mL O2·kg–1·min–1) and poorly correlated with MAS and AAS (r = 0.27 and ρ = 0.32, respectively), possibly due to a ceiling effect. Estimated VO2max from the NEx was not significantly different than measured VO2max and was highly correlated (r = 0.82). Conclusions: The HAP is not a valid indicator of functional capacity for HIV-positive patients on HAART. The lack of functional impairment suggests that, in the absence of other clinically relevant limitations, HIV-positive individuals on HAART may benefit from exercise prescriptions developed similarly for non–HIV-positive individuals, based on the NEx or submaximal testing protocols, without requiring adaptive strategies.

Critical power in adolescent boys and girls — an exploratory study

The purpose of the study was to identify critical power (CP) in boys and girls and to examine the physiological responses to exercise at and 10% above CP (CP+10%) in a sub-group of boys. Nine boys and 9 girls (mean age 12.3 (0.5) y performed 3 constant-load tests to derive CP. Eight of the boys then exercised, in random order, at CP and CP+10% until volitional exhaustion. CP was 123 (28) and 91 (26) W for boys and girls, respectively (p < 0.02), which was equivalent to 75 (6) and 72 (10) % of peak oxygen uptake, respectively (p > 0.47). Boys' time to exhaustion at CP was 18 min 37 s (4 min 13 s), which was significantly longer (p < 0.007) than that at CP+10% (9 min 42 s (2 min 31 s)). End-exercise values for blood lactate concentration (B[La]) and maximal oxygen uptake were higher in the CP+10% trial (5.0 (2.4) mmol.L-1 and 2.15 (0.4) L.min-1, respectively) than in the CP trial, (B[La], 4.7 (2.1) mmol.L-1; maximal oxygen uptake, 2.05 (0.35) L.min-1; p > 0.13). Peak oxygen uptake (expressed as a percentage of the peak value) was not attained at the end of the trials (94 (12) and 98 (14) % for CP and CP+10%, respectively). These results provide information about the boundary between the heavy and severe exercise intensity domains in children, and have demonstrated that CP in a group of boys does not represent a sustainable steady-state intensity of exercise.

Pharmacological and Psychological Effects of Caffeine Ingestion in 40-km Cycling Performance

The ergogenic effects of caffeine are well documented. Research has yet to examine any psychological contribution to this effect. To explore the psychological and pharmacological effects of caffeine in laboratory cycling performance. Fourteen male competitive cyclists performed 14 40-km time trials (eight experimental interspersed with six baseline). The experimental phase consisted of two trials for each of four experimental conditions: informed caffeine/received caffeine, informed no treatment/received caffeine, informed caffeine/received placebo, and informed no treatment/received no treatment. Conditions were nonrandomized. ANOVA was used to estimate main effects and interactions for mean values of power, heart rate, blood lactate, and maximal oxygen uptake. Probabilistic inferences for mean power were based on a smallest worthwhile change of 1.5%. Relative to baseline, a very likely beneficial main effect of receiving caffeine (3.5%; 95% confidence interval 1.5 to 5.5%), and a possibly beneficial main effect of being informed of caffeine (0.7%; -0.7 to 2.1%) were observed. A substantial interaction between belief and pharmacology indicated that caffeine exerted a greater effect on performance in conditions when subjects were informed that they had not ingested it, whereas belief exerted a greater influence on performance in the absence of caffeine (2.6%; -0.7 to 5.9%). A possibly harmful negative placebo (nocebo) effect was observed when subjects were correctly informed that they had ingested no caffeine (-1.9%; -4.1 to 0.3%). No clinically significant changes relative to baseline were observed in mean heart rate. Clear and substantial increases in blood lactate were evident after receipt of caffeine. Data for mean oxygen uptake were unclear. Our data support the ergogenic efficacy of caffeine but suggest that both positive and negative expectations impact performance.

Effect of the o2 time‐averaging interval on the reproducibility of o2max in healthy athletic subjects

Limited research has investigated the most appropriate oxygen uptake (VO2) data averaging method to obtain reliable and valid maximal oxygen uptake (VO2max) values. This study investigated the effect of the VO2 time-averaging interval on the reproducibility of VO2max. Twenty-two competitive distance runners (six female) performed two identical incremental treadmill tests to their limit of exercise tolerance separated by at least 48 h. Commencing at 7 km h(-1), running speed was increased by 1 km h(-1) per minute for five stages and 0.5 km h(-1) thereafter. Breath-by-breath VO2 data collected during each incremental test were time-averaged over 10-, 15-, 20-, 30- and 60-s and the highest averaged VO2 value was regarded as VO2max for each time-averaging interval. The VO2max values derived from different VO2 time-averaging intervals were significantly different for the first (F = 39.6; P<0.001) and second (F = 68.9; P<0.001) incremental test. There was a tendency for VO2max to significantly increase as the time-averaging interval became shorter. The reproducibility of VO2max was similar for all five VO2 time-averages, with no significant differences between the within-subject variance (F = 0.4; P = 0.6). The results of this study suggests that the reproducibility of VO2max is not affected by the length of the VO2 time-average interval. However, VO2max was significantly altered by changing the VO2 time-averaging interval between 10 and 60 s. Consistency in the VO2 time-averaging interval is therefore an important methodological consideration for repeated determinations of VO2max.

Tennis Physiology

The game of tennis has evolved from the wooden-racket era of long, crafty points based on style and finesse, to the current fast paced, explosive sport based on power, strength and speed, where 210 km/h serves are common. This evolution over the last 20 years has led to an increased interest in tennis research. Competitive tennis athletes need a mixture of anaerobic skills, such as speed, agility and power, combined with high aerobic capabilities. The work-to-rest ratios of competitive tennis athletes range between 1 : 3 and 1 : 5, and fatigue has been shown to greatly reduce the hitting accuracy. Competitive male tennis athletes maintain body fat <12% and have maximal oxygen uptake values >50 mL/kg/min, and as high as 70 mL/kg/min. Results from lactate testing in tennis players are inconclusive as some studies have shown increased levels, whilst other studies have shown little or no change. Further investigation is required to determine the production and utilisation effects of lactate from playing tennis. The average length of time to play a point in tennis is <10 seconds and this has declined substantially in the last 20 years. Further research is needed to investigate tournament performance and its effect on fatigue, recovery, hormonal and injury levels. As the game of tennis continues to change, the physiological parameters must be continually investigated to help provide athletes, coaches and trainers with information that will aid in the development of efficient and productive tennis performance and injury prevention programmes.

ANY EFFECT OF GYMNASTICS TRAINING ON UPPER-BODY AND LOWER-BODY AEROBIC AND POWER COMPONENTS IN NATIONAL AND INTERNATIONAL MALE GYMNASTS?

Aerobic and anaerobic performance of the upper body (UB) and lower body (LB) were assessed by arm cranking and treadmill tests respectively in a comparison of national (N) and international (I) male gymnasts. Force velocity and Wingate tests were performed using cycle ergometers for both arms and legs. In spite of a significant difference in training volume (4–12 vs. 27–34 h·wk−1 for N and I, respectively), there was no significant difference between N and I in aerobic and anaerobic performance. Upper body and LB maximal oxygen uptake (O2max) values were 34.44 ± 4.62 and 48.64 ± 4.63 ml·kg−1·min−1 vs. 33.39 ± 4.77 and 49.49 ± 5.47 ml·kg−1·min−1, respectively, for N and I. Both N and I had a high lactic threshold (LT), at 76 and 82% of O2max, respectively. Values for UB and LB force velocity (9.75 ± 1.12 and 15.07 ± 4.25 vs. 10.63 ± 0.95 and 15.87 ± 1.25 W·kg−1) and Wingate power output (10.43 ± 0.74 and 10.98 ± 3.06 vs. 9.58 ± 0.60 and 13.46 ± 1.34 W·kg−1) were also consistent for N and I. These findings confirm the consistency of O2max values presented for gymnasts in the last 4 decades, together with an increase in peak power values. Consistent values for aerobic and anaerobic performance suggest that the significant difference in training volume is related to other aspects of perfomance that distinguish N from I gymnasts. Modern gymnastics training at N and I levels is characterized by a focus on relative strength and peak power. In the present study, the high LT is a reflection of the importance of strength training, which is consistent with research for sports such as wrestling.

Respostas hemodinâmicas, cardiorrespiratórias e ocorrência de lesão muscular no meio aquático e terrestre em mulher não ativa: estudo de caso

The purpose of this study was to compare the effects of a graded dynamic exercise in water and on land on cardiorespiratory responses and muscle damage. The exercise was performed by a woman who had not been involved in any regular, structured exercise program for at least 6 months before participating in the study. The two graded dynamic exercises were performed on cycle ergometer in water and on land, separated by 1 week, reaching the maximal effort. Oxygen consumption was measured using a Gas Analyser (KB1-C, AEROSPORT), systolic and diastolic blood pressures were measured using a sphygmomanometer (Baumanometer) and heart rate was measured with a Sport tester Polar S610. Plasma creatine kinase activity was determined using a commercially available kit (CK-NAC, Bioliquid). Maximal oxygen uptake value on land was 1,56 l.min-1 and in water was 1,64 l.min-1. Maximal heart rate and blood pressure demonstrated a lower response in water. Creatine kinase levels were not alterated in all measures for both environments. Our data suggest that the maximal exercise on a cycle ergometer performed in water reduce cardiovascular workload without risks of muscle damage.

Thermoregulatory responses to exercise: relative versus absolute intensity

The purpose of the present study was to re-examine the relationship between deep body temperature and relative exercise intensity, during running rather than cycling (Saltin and Hermansen, 1966). Twenty male competitive and recreational distance runners, aged 22 + 0.9 years (mean +/- sx), were selected to form two groups, one with high maximal oxygen uptake (VO2max) values (72.8 +/- 0.8 ml x kg(-1) x min(-1)) and the other with moderate values (59.4 +/- 0.7 ml x kg(-1) x min(-1)). The participants completed two 60 min constant-paced treadmill runs at a common speed (absolute intensity) of 10.5 km x h(-1) and at a relative exercise intensity at a speed equivalent to 65% of VO2max. During the relative exercise intensity trial, no differences were found in rectal temperature, skin temperature or heart rate between groups. However, when running at the common speed, differences were identified in rectal temperature. At 60 min, rectal temperature was 37.70 +/- 0.19 degrees C and 38.19 +/- 0.11 degrees C for the high and moderate VO2max groups, respectively (P < 0.05). Sweat lost was significantly higher in the moderate VO2max group (moderate: 1.05 +/- 0.06 kg x h(-1); high: 0.82 +/- 0.08 kg x h(-1); P < 0.05). Heart rates were also different between groups over the first 20 min during the common speed trial (P < 0.05). The results of the present study support the findings of Saltin and Hermansen (1966), in that the set-point at which temperature is maintained is related to the relative exercise intensity.

Muscle oxygenation trends during dynamic exercise measured by near infrared spectroscopy.

During the last decade, NIRS has been used extensively to evaluate the changes in muscle oxygenation and blood volume during a variety of exercise modes. The important findings from this research are as follows: (a) There is a strong correlation between the lactate (ventilatory) threshold during incremental cycle exercise and the exaggerated reduction in muscle oxygenation measured by NIRS. (b) The delay in steady-state oxygen uptake during constant work rate exercise at intensities above the lactate/ventilatory threshold is closely related to changes in muscle oxygenation measured by NIRS. (c) The degree of muscle deoxygenation at the same absolute oxygen uptake is significantly lower in older persons compared younger persons; however, these changes are negated when muscle oxygenation is expressed relative to maximal oxygen uptake values. (d) There is no significant difference between the rate of biceps brachii and vastus lateralis deoxygenation during arm cranking and leg cycling exercise, respectively, in males and females. (e) Muscle deoxygenation trends recorded during short duration, high-intensity exercise such as the Wingate test indicate that there is a substantial degree of aerobic metabolism during such exercise. Recent studies that have used NIRS at multiple sites, such as brain and muscle tissue, provide useful information pertaining to the regional changes in oxygen availability in these tissues during dynamic exercise.

Estimation of VO2max from the ratio between HRmax and HRrest--the Heart Rate Ratio Method.

The effects of training and/or ageing upon maximal oxygen uptake ( VO(2max)) and heart rate values at rest (HR(rest)) and maximal exercise (HR(max)), respectively, suggest a relationship between VO(2max) and the HR(max)-to-HR(rest) ratio which may be of use for indirect testing of VO(2max). Fick principle calculations supplemented by literature data on maximum-to-rest ratios for stroke volume and the arterio-venous O(2) difference suggest that the conversion factor between mass-specific VO(2max) (ml.min(-1).kg(-1)) and HR(max).HR(rest)(-1) is approximately 15. In the study we experimentally examined this relationship and evaluated its potential for prediction of VO(2max). VO(2max) was measured in 46 well-trained men (age 21-51 years) during a treadmill protocol. A subgroup ( n=10) demonstrated that the proportionality factor between HR(max).HR(rest)(-1) and mass-specific VO(2max) was 15.3 (0.7) ml.min(-1).kg(-1). Using this value, VO(2max) in the remaining 36 individuals could be estimated with an SEE of 0.21 l.min(-1) or 2.7 ml.min(-1).kg(-1) (approximately 4.5%). This compares favourably with other common indirect tests. When replacing measured HR(max) with an age-predicted one, SEE was 0.37 l.min(-1) and 4.7 ml.min(-1).kg(-1) (approximately 7.8%), which is still comparable with other indirect tests. We conclude that the HR(max)-to-HR(rest) ratio may provide a tool for estimation of VO(2max) in well-trained men. The applicability of the test principle in relation to other groups will have to await direct validation. VO(2max) can be estimated indirectly from the measured HR(max)-to-HR(rest) ratio with an accuracy that compares favourably with that of other common indirect tests. The results also suggest that the test may be of use for VO(2max) estimation based on resting measurements alone.