Assessing motor competence in kicking in individuals with Down syndrome through wearable motion sensors.

BACKGROUND: Kicking a ball is a very frequent action in sport and leisure time activities and a low proficiency in this skill could limit the participation in recreational sport activities. This issue is emphasised in individuals with Down syndrome (IDS) for which data about motor competence in kicking are limited to children. Here, we aim at evaluating the kicking competence of IDS combining a qualitative and a quantitative method. METHODS: Twenty-three adult IDS and 21 typically developed individuals (ITD) volunteered to participate in the study. Peak-to-peak 3D linear acceleration and angular velocity were recorded at 200 samples/s using two inertial measurement units placed on the lower back and lateral malleolus of the dominant limb during kicking. Motor competence in kicking was assessed according to the criteria proposed in the test of gross motor development version 3 (TGMD-3). RESULTS: Individuals with Down syndrome showed lower motor competence (ITD: 5.9 ± 1.2; IDS: 3.2 ± 2.0) and lower angular velocities about the cranio-caudal (ITD: 3.0 ± 1.8; IDS: 2.1 ± 1.1 rad/s) and medio-lateral axes (ITD: 4.5 ± 1.5; IDS: 3.0 ± 1.1 rad/s) of the trunk compared with ITD. Shank angular velocity about the medio-lateral axis was lower in IDS (ITD: 14.3.6 ± 4.0; IDS: 9.9 ± 2.8 rad/s). CONCLUSIONS: The lower trunk angular velocity in IDS may limit the possibility to rely on the proximal-to-distal sequencing commonly observed in kicking and generate high shank angular velocity upon ball impact. The lower trunk angular velocity may result from orthopaedic features of the pelvic girdle and possibly from a poorer neuromuscular control of core muscles.

Stress related changes during TeamGym competition.

AIM: The aim of the present study was to investigate the stress--related changes of a TeamGym competition considering both physiological [i.e. salivary cortisol (sC) and alpha--amylase (sAA)] and psychological (i.e. state anxiety) responses in relation to exercise intensity and competition outcomes. METHODS: Eleven (5 males and 6 females) elite TeamGym athletes (age: 21--28 yrs) were administered the State--Trait Anxiety Inventory before an official international TeamGym competition. sAA and sC samples were collected 15 minutes prior to competition, after each apparatus, 10--min and 30--min after competition. Exercise intensity was estimated by heart rate (HR) recording and performance was evaluated by three international judges. All these parameters were correlated with competition outcomes. RESULTS: TeamGym competition posed a low exercise load (most of exercise was performed below 85% of the individual HR max ). Significant increases (P<0.004) in sAA (3.53 fold induction) and state anxiety (P=0.045) were observed, with respect to baseline values. Conversely, sC remained stable throughout the competition. Significant (P=0.029) correlation between sAA, state anxiety and competition outcomes emerged. CONCLUSIONS: Present findings provide the first evidence that the psycho--physiological stress response prior to and during competition can affect performance outcome, especially in a technical sport such as TeamGym.

Analysis of session-RPE and profile of mood states during a triathlon training camp.

AIM: The aim of the present study was to monitor the internal training load and profile of mood states (POMS) during a training camp in junior-elite triathletes. METHODS: Sixteen (10 male and 6 female) young triathlon athletes (junior-elite: 18±1 yrs) were included in this study. All triathletes had been training for 7±3 years, and regularly trained 4 times a week 3h per session, throughout the year. The training camp (5 days) included two daily supervised training sessions. The CR-10RPE scale was used 30 minutes after every training session to evaluate session-RPE. POMS was administered 3 times during the training camp: at the beginning, on the 3rd day, and at the end of training camp. RESULTS: Session-RPE throughout the different training days showed significant differences (P<0.001). POMS scores showed a significant increase (P<0.001) in fatigue from the first (7.8±1.4), to the third (10.5±2.2) and to the last day of training (14.2±3.4). At the end of the camp, lower (P<0.01) vigour values (12.7±2.8) emerged with respect to the first day (15.8±3.0), whereas anger decreased (P=0.015) the last day (8.6±2.2) with respect to the intermediate evaluation (9.6±2.7). CONCLUSION: The 45% increase in fatigue, the 24% decrease in vigour, and the intraindividual variability in session RPE that emerged, indicates that young triathletes need to be monitored closely during training camps in order to individualize training to avoid training maladaptation such as non-functional overreaching.

Stress related changes during a half marathon in master endurance athletes.

AIM: The aim of the present study was to investigate heart rate (HR), salivary cortisol (sC) alpha-amylase (sAA) and rating of perceived exertion (RPE) in relation to competition outcome during a half marathon. METHODS: HR was monitored and salivary samples were collected during an official half marathon in five Master endurance runners (age 47 ± 7 years). RPE was collected using a 100-mm Visual Analogue Scale (VAS) 30 minutes after the end of competition. RESULTS: Performance corresponded to 94% of their personal best (PB). Athletes spent 53.7% of total race time at intensities above 95% HRmax. RPE showed values of 68 ± 8 mm. With respect to pre-competition values (25.54 ± 6.39 nmol/L), sC concentrations significantly increased (P=0.043) by 59% immediately after the race (40.54 ± 3.95 nmol/L) and remained elevated until 1 h post exercise. Pre-competition sAA concentrations (90.59 ± 42.86 U/mL) were 118% higher (P=0.043) with respect to time-matched baseline values (197.92 ± 132 U/mL). sAA increased (192%; P=0.043) immediately after the race and was higher than time-matched resting samples. The better each athlete performed the greater cortisol increase during exercise (P<0.001). Performance was not correlated to the anticipatory sAA (the percent difference between pre-competition values and time-matched baseline ones) or to the sAA increase during exercise. CONCLUSION: This is the first attempt to study the stress-related responses during official endurance competitions in master runners. Although the strict criteria of inclusion might have limited the statistical significance, the present findings indicate that endurance competition is a remarkable stressor for psycho-physiological aspects of master athletes.

Does the junior IAAF athletic world championship represent a springboard for the success in the throwing events? A retrospective study.

AIM: The aim of the present study was to analyze how many finalists of the IAAF World Junior Championships (WJC) in the throwing events were present in the senior IAAF ranking at the end of 2012. METHODS: The results of the 8 male and the 8 female finalists of all throwing events of the last 5 editions of the WJC from the 2002 edition were gathered. We analyzed how many athletes were missing from the IAAF ranking in 2012. For those athletes that did not drop out we monitored their progression in performance comparing their WJC and their 2012 performance. Moreover, we evaluated if the relative age effects (RAE) influenced drop out rate. RESULTS: Drop out rate was 58% in 2002, 59% in 2004, 39% in 2006, and 28% in 2008 and in 2010. The female javelin throwers showed the highest drop out rate (100%) in 2002, while the female hammer throwers showed the lowest drop out rate (0%) in 2008. Performance decreased for all male shot putters, discus and hammer throwers (P<0.001). For females and for male javelin throwers, performance increased (P<0.001). RAEs showed no significant influence on drop out rate CONCLUSION: Even if 8 of the finalists won a medal at the Olympic Games or at the World Championships, it is still not clear if participation at the WJC is a prerequisite to success at a senior level, given the elevated drop out rate observed in the present study.

Cardiovascular responses during an indoor race walking competition.

AIM: This study aims to examine the cardiovascular responses during an indoor race walking competition over the distance of 3-km for female and 5-km for male athletes. METHODS: During the Italian indoor RW Championship heart rate was monitored on eleven well trained race walkers (five men and six women) and then refereed as percentages of individuals' theoretical maximum heart rate (206-0.7·age). To provide a measure of relative intensity, five HR zones were assessed. Alterations in % HRmax both for the five and three 1000-m split distances were determined. RESULTS: During the 5-km race the athletes spent 79.7% (15 min 45 s) at HR5 (i.e., 90-100% of HRmax). Specifically, % HRmax increased by 10% in the last compared to the first 1000-m sector (P=0.006, effect size = 2.47±0.83, very large), with the first 1000-m sector lower than the subsequent ones (P=0.01, effect size=2.17 to 2.47, very large). While, for the 3-km the athletes spent 86.9% (11 min 35 s) at HR5 (i.e., 90-100% of HRmax) with no differences observed in the % HRmax between the three 1000-m sectors (P>0.01). CONCLUSION: The dissemination of performance and physical attributes identified within the present study reveal that the exercise intensity of indoor race walking competitions has a high-intensity profile and will assist coaches and athletes in formulating appropriate training, competition and recovery.

The use of session RPE for interval training in master endurance athletes: should rest be included?

AIM: The aim of this study was to evaluate the effectiveness of the session rate of perceived exertion (RPE) method as a tool to quantify internal training load during interval training in master athletes. In addition, we investigated whether it is appropriate to take into account rest periods when calculating the session-RPE. METHODS: Eight male master endurance athletes (age: 45.3±7.3 years; stature: 1.74±0.06 m; body mass: 64.9±9.1 kg) were monitored during an interval training session consisting of 5 x 1000 m performed at 95% of vVO2max with 5 min rest between bouts. Edwards' summated heart rate zone method was used as a reference measure and the session RPE rating was obtained using the CR10 Borg's scale modified by Foster. RESULTS: High (r: 0.82; R2: 0.67) and significant (P=0.013) correlation was observed between the Edwards' heart rate (HR) and the session-RPE method when rest periods are taken into account; meanwhile a higher significant correlation (r: 0.86; R2: 0.74; P=0.003) was found between Edwards' HR and the session-RPE methods when rest periods were eliminated for the session-RPE computation. CONCLUSION: Despite the rest period exclusion from the computation of session RPE seems more appropriate, the statistical analysis indicates that there is no significant difference between the two correlation coefficients. These findings suggest that the session-RPE can be a useful tool to monitor internal training load during interval training and that the inclusion/exclusion of rest periods in its computation needs further investigation.

Diagnosing overtraining in athletes using the two-bout exercise protocol.

OBJECTIVE: In this work, whether a two-bout exercise protocol can be used to make an objective, immediately available distinction between non-functional over reaching (NFO) and overtraining syndrome (OTS) was studied. DESIGN: Underperforming athletes who were diagnosed with the suspicion of NFO or OTS were included in the study. Recovery of the athletes was monitored by a sports physician to retrospectively distinguish NFO from OTS. SETTING: Sports medicine laboratory PARTICIPANTS: The protocol was started and completed by 10 underperforming athletes. NFO was retrospectively diagnosed in five athletes, and OTS was diagnosed in five athletes. INTERVENTIONS: A two-bout maximal exercise protocol was used to measure physical performance and stressinduced hormonal reactions. MAIN OUTCOME MEASUREMENTS: Exercise duration, heart rate and blood lactate concentration were measured at the end of both exercise tests. Venous concentrations cortisol, adrenocorticotrophic hormone (ACTH), prolactin and growth hormone were measured both before and after both exercise tests. RESULTS: Maximal blood lactate concentration was lower in OTS compared with NFO, while resting concentrations of cortisol, ACTH and prolactin concentrations were higher. However, sensitivity of these measures was low. The ACTH and prolactin reactions to the second exercise bout were much higher in NFO athletes compared with OTS and showed the highest sensitivity for making the distinction. CONCLUSIONS: NFO might be distinguished from OTS based on ACTH and prolactin reactions to a two-bout exercise protocol. This protocol could be a useful tool for diagnosing NFO and OTS; however, more data should be collected before this test can be used as the gold standard.

Physiological and technical aspects of ''6-a-side'' soccer drills.

AIM: The purposes of the present study were: 1) to evaluate heart rate and technical-tactical differences, if any, during ''6-a-side'' drills, played on 2 pitch dimensions (30x40 m and 50x40 m) and duration (3 min and 8 min); 2) to assess the variability of data between repeated experimental sessions; 3) to evaluate training intensities from heart rate at lactate threshold. METHODS: Laboratory measurements of maximal oxygen consumptions, maximum heart rates and lactate thresholds were performed on 9 soccer players who played at Regional level. For test and retest field sessions, the exercise intensities were calculated from heart rate monitoring and match analysis (number of actions, consecutive passes, players involved in a single action) was performed. RESULTS: No significant differences were found in heart rate frequency distributions between test and retest sessions. Statistically significant differences in frequency distributions of heart rate were found only between the 3 min and 8 min drills played on the 40x50 m pitch. Regarding exercise intensity, significant differences (P<0.01) were found for pitch dimension, with higher intensities shown during the 30x40 m pitch trials. When technical data were related to time units, no differences were found among experimental settings. CONCLUSIONS: These data indicate that coaches could better modulate the training intensity by varying the pitch dimension, with the smaller individual playing area (30x40 m) having a large impact on the metabolic demands of exercise.

Hormonal responses during prolonged exercise are influenced by a selective DA/NA reuptake inhibitor.

OBJECTIVE: A decrease in dopamine activity is thought to lead to a reduction in motivation and arousal and therefore to the "central" component of fatigue. The purpose of the present study was to investigate the effects of a dopamine (DA) noradrenaline (NA) reuptake inhibitor, bupropion (Zyban), on exercise performance and on the hormonal response to exercise. METHODS: Eight healthy well trained male cyclists (Watt(max) 397+/-15 W) participated in the study. Subjects completed one maximal exercise test (to determine maximal power output Watt(max)), and two endurance performance tests (time trials) in a double blind randomised cross-over design. Subjects took either placebo capsules (lactose) or 2 x 300 mg bupropion (BUP). Blood samples were collected for adrenocorticotropin (ACTH), prolactin, cortisol, growth hormone, beta-endorphins, and catecholamines. RESULTS: Performance was not influenced by BUP (placebo: 89+/-1 min; BUP 2 x 300 mg: 89+/-0.7 min). All hormones increased during exercise in all trials. Cortisol plasma concentrations were significantly higher in the BUP trial at rest, at min 60, and at the end of exercise, while beta-endorphins were higher in the BUP trial at the end of exercise and during recovery, and ACTH at the end of exercise. CONCLUSION: From the present results, we can conclude that bupropion had a more marked central noradrenergic effect (compared to dopaminergic) on the hormonal response to exercise, but no effect on the outcome of performance.

Hormonal responses in athletes: the use of a two bout exercise protocol to detect subtle differences in (over)training status.

In overtrained athletes, several signs and symptoms have been associated with the imbalance between training and recovery. However, reliable diagnostic markers for distinguishing between well-trained, overreached (OR) and overtrained (OT) athletes are lacking. A hallmark feature of overtraining syndrome (OTS) is the inability to sustain intense exercise and recover for the next training or competition session. We therefore devised a test protocol utilizing two bouts of maximal work. With this test protocol we tried to establish a difference in hormonal responses between the training status of T and OR athletes. Seven well-trained cyclists participated in this study and were tested before and after a training camp. We also present the data of one OT motocross athlete who was clinically diagnosed as overtrained. All athletes performed two maximal exercise tests separated by 4 h. Blood was analyzed for cortisol, adrenocorticotrophic hormone (ACTH), growth hormone and prolactin (PRL). Performance decreased by 6% between the first and the second exercise test in the OR group and by 11% in the OT subject. Moreover, during the second exercise test there were more marked differences between the T and OR athletes; in particular, the OT subject did not show an increase in some of the hormonal responses. PRL increased only by 14% in the OT subject's second test and there was a 7% decrease in ACTH. The two exercise approach enables us to detect subtle performance decrements that will not be identified by one exercise trigger. The hormonal responses to the second exercise test were different between the T and OR athletes (the increase in the T group was higher than in the OR that was higher than in the OT). The results of the case presentation of an overtrained athlete provide evidence of an altered and dysfunctional hypothalamic-pituitary axis response to two bouts of maximal exercise. These findings can be used to develop markers for diagnosis of OTS and to begin to address the pathologic mechanism operative in the syndrome, as well as providing an outcome measure to evaluate possible therapeutic regimes.

Effects of venlafaxine on extracellular 5-HT, dopamine and noradrenaline in the hippocampus and on peripheral hormone concentrations in the rat in vivo.

The purpose of the present study was to study the effect of an acute dose of the serotonin (5-HT) - noradrenaline (NA) reuptake inhibitor venlafaxine on extracellular concentrations of 5-HT, NA and dopamine (DA) in the hippocampus and on the peripheral hormone concentrations in freely moving rats. Blood obtained from a catheter placed in the vena femoralis was analyzed for adrenocorticotropin (ACTH), beta-endorphins, prolactin (PRL), growth hormone (GH) and cortisol. Collections are referred to pre and post injection of 20 mg/kg of venlafaxine. Extracellular hippocampal NA and 5-HT as determined with in vivo microdialysis increased significantly after drug injection. PRL and ACTH were significantly affected by the drug. At the selected dose venlafaxine is able to increase the release of 5-HT but also of NA in rat hippocampus. Due to the dual reuptake properties of the drug and the functional interconnection of the NA and the 5-HT systems, the observed effects on peripheral hormones are possibly mediated by a combined action of these 2 systems.

Effect of bupropion on hippocampal neurotransmitters and on peripheral hormonal concentrations in the rat.

The purpose of the present study was to administer an acute dose of the dual dopamine norepinephrine reuptake blocker bupropion in freely moving rats and to monitor the extracellular neurotransmitter concentrations in the hippocampus via in vivo microdialysis and the peripheral hormonal concentrations via catheterization. A microdialysis probe was inserted in the hippocampus, and samples for serotonin, dopamine, and norepinephrine were collected every 20 min before and after the injection of 17 mg/kg of bupropion, for a total sampling time of 180 min. A catheter was placed in the vena femoralis of the second group of rats, and blood samples were collected before and after bupropion injection for quantification of growth hormone, prolactin, corticosterone, adrenocorticotropin hormone, and beta-endorphins. All neurotransmitter levels (dopamine, norepinephrine, and serotonin) significantly increased after bupropion injection. This was accompanied by a significant decrease in prolactin concentrations, whereas the other hormones showed no statistically significant variation. It can, therefore, be concluded that, although bupropion has dual reuptake proprieties, the observed effects both at the central and at the peripheral level seem to be ruled by the dopaminergic system.

Brain microdialysis in exercise research.

During the last 5 to 10 years, the microdialysis technique has been used to explore neurotransmitter release during exercise. Microdialysis can collect virtually any substance from the brains of freely moving animals with a limited amount of tissue trauma. It allows the measurement of local neurotransmitter release in combination with ongoing behavioural changes such as exercise. Several groups examined the effect of treadmill running on extracellular neurotransmitter levels. Microdialysis probes were implanted in different brain areas to monitor diverse aspects of locomotion (striatum, hippocampus, nucleus accumbens, frontal cortex, spinal cord), food reward (hypothalamus, hippocampus, cerebral cortex), thermoregulation (hypothalamus). Some studies combined microdialysis with running on a treadmill to evaluate motor deficit and improvement following dopaminergic grafts in 6-hydroxydopamine lesioned rats, or combined proton nuclear magnetic resonance spectroscopy and cortical microdialysis to observe intra- plus extracellular brain glucose variations. This method allows us to understand neurotransmitter systems underlying normal physiological function and behaviour. Because of the growing interest in exercise and brain functioning, it should be possible to investigate increasingly subtle behavioural and physiological changes within the central nervous system. There is now compelling evidence that regular physical activity is associated with significant physiological, psychological and social benefits in the general population. In contrast with our knowledge about the peripheral adaptations to exercise, studies relating exercise to brain neurotransmitter levels are scarce. It is of interest to examine the effect of short and long term exercise on neurotransmitter release, since movement initiation and control of locomotion have been shown to be related to striatal neurotransmitter function, and one of the possible therapeutic modalities in movement, and mental disorders is exercise therapy. Until very recently most experimental studies on brain chemistry were conducted with postmortem tissue. However, in part because of shortcomings with postmortem methods, and in part because of the desire to be able to directly relate neurochemistry to behaviour, there has been considerable interest in the development of 'in vivo' neurochemical methods. Because total tissue levels may easily mask small but important neurochemical changes related to activity, it is important to sample directly in the extracellular compartment of nervous tissue in living animals. Since the chemical interplay between cells occurs in the extracellular fluid, there was a need to access this compartment in the intact brain of living and freely moving animals. Estimation of the transmitter content in this compartment is believed to be directly related to the concentration at the site where these compounds are functionally released: in the synaptic cleft. As measurements in the synapse are not yet possible, in vivo measurements in the extracellular fluid appear to provide the most directly relevant information currently available. This article provides an overview of the in vivo microdialysis technique as a method for measuring in the extracellular space, and its application in exercise science. Although this technique has been used in different tissues such as brain, adipose tissue, spinal cord and muscle, in animals as well as humans, we will focus on the use of this in vivo method in brain tissue. Recently two excellent reviews on the application of microdialysis in human experiments especially in subcutaneous tissue have been published, and we refer the interested reader to these articles.

Exercise performance is not influenced by a 5-HT reuptake inhibitor.

The purpose of the present study was to examine the effect of a selective serotonin (5-HT) reuptake inhibitor (SSRI) on exercise performance during a 90 min time trial. Eight well trained male cyclists (VO2max 68.1 +/- 9.5 ml/kg/min) performed three 90 min time trials at 65% Wattmax. Blood samples were collected via an indwelling venous catheter for adrenocorticotropin hormone (ACTH), prolactin (PRL), cortisol, catecholamines, growth hormone (GH) and beta-endorphins. The evening before and the morning of the time trials, the subjects ingested a capsule containing either placebo (lactose) or 20 mg Fluoxetine-HCI (Prozac, Ely Lilly Belgium). A double blind, randomized, placebo controlled, cross-over design was performed. Performance was not influenced by the SSRI. As expected, all blood parameters increased significantly during exercise (p < 0.05). During the SSRI trial most parameters were slightly lower but only significantly for endorphins and PRL (p < 0.05). The results demonstrate that performance is not influenced by an SSRI, although some plasma hormones indicate a central effect of the drug. Surprisingly, the increases in PRL and endorphins were lower during the SSRI trial, meaning that the hormonal modulation during exercise might be regulated by the interaction between neurotransmitters rather than by serotonin alone.

Force generation performance and motor unit recruitment strategy in muscles of contralateral limbs.

The purpose of the present study was to determine whether the motor unit (MU) recruitment strategy of the agonist and antagonist muscles in the dominant arm differs from that in the non-dominant arm. The median frequency (MF) of the power density spectrum (PDS) of the electromyogram (EMG) was used as a tracking parameter to describe the MU recruitment. In 8 subjects the EMG was recorded from the biceps brachii and triceps brachii of each limb during isometric elbow flexion performed in a ramp fashion. Force was increased from 0 to 100% of the maximum voluntary contraction (MVC) in 3 s following a track displayed on an oscilloscope. When comparing the dominant versus non-dominant arm we found no statistical difference in the MU recruitment pattern of the biceps brachii and the triceps. Because the dominant arm was not always the better performing arm, we grouped the data according to the ability of the subjects to track the ramp signal. In this case we found a statistically significant difference between the better and worse performing arm in the full MU recruitment of the biceps. A more precise and accurate control of the increase in force was obtained when the central nervous system selected a slower and prolonged recruitment of MUs in the agonist muscle.

Cost of walking and locomotor impairment.

The aim of the present study was to evaluate the importance and the necessity of metabolic measurements to quantify locomotor impairment in a clinical context. Oxygen consumption, heart rate, pulmonary ventilation and walking speed were measured during locomotion in 14 normal subjects, used as a control group, and 82 patients with different pathologies [hemiparetic, paraparetic, tetraparetic, orthopaedic and paraplegic patients, who walked using a reciprocating gait orthosis (RGO)]. The subjects were characterized on the basis of a cumulative impairment score (CIS), based on clinical scales commonly used to evaluate impairment and disability in locomotion. Appropriate indices of energy, cardiac and ventilatory costs expressed per metre walked, globally called physiological costs, were obtained. It resulted that the most comfortable speed (MCS) of normal subjects was significantly higher than that of each group of patients. Normal subjects' physiological costs were found to be significantly lower than those of patients who needed either a device or the help of a person to walk. All measured parameters correlated significantly with each other. The MCS was found to be the most correlated parameter with the CIS (r = 0.8), and therefore it must be considered the best single measurement, if only one is to be used. Measurements more precise than MCS, such as the physiological costs, may be necessary in clinical trials.

Training-induced alterations of carbohydrate metabolism in women: women respond differently from men.

We examined the hypothesis that glucose flux was directly related to relative exercise intensity both before and after a 12-wk cycle ergometer training program [5 days/wk, 1-h duration, 75% peak O2 consumption (VO2 peak)] in healthy female subjects (n = 17; age 23.8 +/- 2.0 yr). Two pretraining trials (45 and 65% of VO2 peak) and two posttraining trials [same absolute workload (65% of old VO2 peak) and same relative workload (65% of new VO2 peak)] were performed on nine subjects by using a primed-continuous infusion of [1-13C]- and [6,6-2H]glucose. Eight additional subjects were studied by using [6, 6-2H]glucose. Subjects were studied postabsorption for 90 min of rest and 1 h of cycling exercise. After training, subjects increased VO2 peak by 25.2 +/- 2.4%. Pretraining, the intensity effect on glucose kinetics was evident between 45 and 65% of VO2 peak with rates of appearance (Ra: 4.52 +/- 0.25 vs. 5.53 +/- 0.33 mg . kg-1 . min-1), disappearance (Rd: 4.46 +/- 0.25 vs. 5.54 +/- 0.33 mg . kg-1 . min-1), and oxidation (Rox: 2.45 +/- 0.16 vs. 4.35 +/- 0.26 mg . kg-1 . min-1) of glucose being significantly greater (P