Incremental Graded Exercise Test Research Articles

The efficacy of a verification stage for determining O2max and the impact of sampling intervals.

It is unknown whether oxygen uptake (V̇O2) sampling intervals influence the efficacy of a verification stage following a graded exercise test (GXT). Fifteen females and 14 males (18-25 years) completed a maximal treadmill GXT. After a 5​min recovery, the verification stage began at the speed and grade corresponding with the penultimate stage from the GXT. Maximal oxygen consumption (V̇O2max) from the incremental GXT (iV̇O2max) and V̇O2max from the verification stage (verV̇O2max) were determined using 10 seconds (s), 30​s, and 60​s from breath​×​breath averages. There was no main effect for V̇O2max measure (iV̇O2maxvs. verV̇O2max) 10​s ([47.9​±​8.31] ml∙kg-1∙min-1 vs [48.85​±​7.97] ml∙kg-1∙min-1), 30​s ([46.94​±​8.62] ml∙kg-1∙min-1 vs [47.28​±​7.97] ml∙kg-1∙min-1), and 60​s ([46.17​±​8.62] ml∙kg-1∙min-1 vs [46.00​±​8.00] ml∙kg-1∙min-1]. There was a stage​×​sampling interval interaction as the difference between (verV̇O2max-iV̇O2max) was greater for 10-s than 60-s sampling intervals. The verV̇O2max was > 4% higher than iV̇O2maxin 31%, 31%, and 17% of the tests for the 10-s, 30-s, and 60-s sampling intervals respectively. Sensitivity for the plateau was < 30% for 10-s, 30-s, and 60-s sampling intervals. Specificity ranged from 44% to 60% for all sampling intervals. Sensitivity for heart rate​+​respiratory exchange ratio was > 90% for all sampling intervals; while specificity was < 25%. Findings from the present study suggest that the efficacy of verification stages for eliciting a higher V̇O2max may be influenced by the sampling interval utilized.

Effect of Noninvasive Static Human Data on Maximum Data in Exercise.

Maximum data in exercise (Max-Ex), including maximum heart rate (HRmax), peak oxygen uptake (VO2pk), maximum power (MaxP), etc., are frequently used, whether it is for the determination of exercise intensity, the measurement of an athlete’s performance, assessment of recovery from disease, and so on. However, very often this choice does not take into account the targeted individual. We recruited 32 males and 29 females to undergo an incremental graded exercise test (GXT). Therefore, our study seeks to determine variations in Max-Ex, according to the noninvasive static human data (Non-In data). Data showed a significant relationship (p < 0.001) between body composition and Max-Ex. Of the 41 types of Non-In data we collected in communities, the body composition generally showed high correlation (maximum r = 0.839). 57.5% of the data, of which r > 0.6 were about body composition. The muscle-related body composition data had a greater effect on power, and the fat-related ones had a greater effect on HRmax and VO2pk. For some types of Max-Ex, the older and younger ones showed specific differences. Therefore, these results can be employed to adequately prescribe personalized health promotion programs according to diversity and availability, and have some reference value for other studies using Max-Ex.

Relationship Between Maximal Fat Oxidation And Ventilatory Threshold In Endurance Trained Males

PURPOSE: Training above ventilatory threshold (VT), and corresponding heart rate, have resulted in improvements in aerobic capacity; the ability to oxidize fatty acids is a limiting factor in endurance performance. Additionally, little is known about the contribution of body composition on maximal fat oxidation (Fatmax). The purpose of this study was to characterize Fatmax and its relationship to VT in endurance trained young adult males. A secondary purpose was to understand the impact of body composition on Fatmax. METHODS: 25 trained males (Age: 22.2 ± 2.4 yrs; Height:177.0 ± 4.8 cm; Weight: 75.3 ± 6.9 kg; VO2max: 50.5 ± 14.6 mL/kg/min) were assessed for body composition using dual-energy X-ray absorptiometry to estimate lean mass (LM), fat mass (FM), and percent body fat (%BF). All subjects performed an incremental graded exercise test to volitional exhaustion. Fatmax was determined as the exercise intensity (%VO2max) at which the highest rate of fat oxidation was observed. VT was determined automatically from the software as the point by which respiration increased to compensate for CO2 and lactate accumulation. Paired t-tests were used to determine the differences between Fatmax and VT%VO2max, FatmaxVO2 and VTVO2, and HR at Fatmax and VT. Multiple linear regression was used to analyze the influence of body composition on Fatmax. RESULTS: There were no significant differences between Fatmax and VT%VO2 (Mean Difference ± Standard Error: -0.2 ± 0.1%; p = 0.107) or FatmaxVO2 and VTVO2 (-3.4 ± 3.1 L/min; p = 0.288). FatmaxHR was significantly lower than VTHR (-11.7 ± 3.1 bpm; p = 0.001). LM, FM, %BF did not significantly influence Fatmax (F = 0.888, R2 = 0.13, p = 0.464). CONCLUSIONS: The similar intensity observed between VT and Fatmax suggests training above VT could be a useful strategy for maximizing fat oxidation during exercise, thereby supporting glycogen sparing in addition to enhanced training volume and exercise adaptations. Body composition does not appear to be an important factor for Fatmax in young males.

Evaluation of cobalt as a performance enhancing drug (PED) in racehorses

Cobalt is a required trace element in animals, but administration in excess is considered dangerous and potentially performance enhancing in equine athletes. This study seeks to determine if cobalt may actually act as a performance enhancing drug (PED) by altering biochemical parameters related to red blood cell production as well as markers of aerobic and anaerobic exercise performance. In addition, for adequate regulation of naturally occurring substances, such as cobalt, its distribution among the population must be defined. In order to identify this distribution, plasma Cobalt was determined from 245 Standardbred horses with no cobalt supplementation from farms in New York and New Jersey, including horses at the Rutgers University Equine Science Center. Samples were analysed by Inductively Coupled Plasma Mass Spectrometry. Seven healthy, race fit Standardbreds (4 geldings, 3 mares, age: 5±3 years, ~500 kg) were used for the PED experiment. An incremental graded exercise test (GXT) to measure maximal aerobic capacity (V̇O2max) and markers of performance, measurement of plasma volume and blood volume as well as the measurement of lactate, erythropoietin (EPO), and various blood haematological factors were determined 7 days prior to cobalt administration. Each horse was administered a sterile solution of cobalt salts (50 mg of elemental Co as CoCl2 in 10 ml of saline, IV) at 9 AM on three consecutive days via the jugular vein. Blood samples were obtained from the contralateral jugular vein before and at 1, 2, 4 and 24 h after administration. Plasma and blood volume were measured one day after the last dose of cobalt, and a post administration GXT was performed the next day. Horses were observed for signs of adverse effects of the cobalt administration (agitation, sweating, increased respiration, etc.). Plasma cobalt concentration increased from a pre-administration mean of 1.6±0.6 to 369±28 μg/l following 3 doses of the cobalt solution (P&lt;0.05). This Co concentration was unaccompanied by changes in aerobic or anaerobic performance, plasma EPO concentration, plasma volume, resting blood volume, total blood volume, or estimated red blood cell volume (P&gt;0.05). There were no observed adverse effects.

Relationship between individual ventilatory threshold and maximal fat oxidation (MFO) over different obesity classes in women.

ObjectiveThe use of the Individual Ventilatory Threshold (IVT), as parameter to prescribe exercise intensity in individuals with obesity, has become more frequent during the last years. This study aimed to evaluate the relationship between IVT and Maximal Fat Oxidation (MFO) in women with obesity.MethodsFifty-two obese female adults (age = 43.6±10.9 years; BMI = 38.5±5.2 kg/m2) were included in this study. According to the BMI classification, subjects were divided into three groups: Obese Class I (OBI, n = 16); Obese Class II (OBII, n = 20) and Obese Class III (OBIII, n = 16). All subjects performed an incremental graded exercise test to evaluate peak oxygen uptake (VO2peak), IVT and MFO. MFO was evaluated using a stoichiometric equation. Fat max zone was determined for each subject within 10% of fat oxidation rates at MFO. For each HR, %HRmax, VO2 and %VO2peak variable, Pearson’s correlation test was done between IVT and MFO exercise intensity. When statistical correlation was found we used a comparative statistical analysis to assess differences between IVT and MFO. Statistical significance was set at P ≤ 0.05.ResultsFor each HR, %HRmax, VO2 and %VO2peak variable there was a positive significant correlation (P<0.01) between IVT and MFO. No significant differences were found for HR, %HRmax, and VO2 between IVT and MFO. %VO2peak was significantly higher at IVT than at MFO (P = 0.03).MFO rates were significantly higher in OBIII women than in women of the other two classes. In all subjects, IVT was within the fat max zone.ConclusionThe use of HR and VO2 corresponding to IVT could be a useful parameter not only to improve cardiorespiratory fitness but also to prescribe physical activity that maximize fat oxidation in obese subjects.

Heart Rate Variability in Marathon Runners During Steady State Exercise and a Graded Exercise Test

Heart rate variability (HRV) analysis offers insight into health status, where greater HRV is associated with better cardiovascular function. Unlike most HRV techniques, which require stationarity of data (e.g., rest), detrended fluctuation analysis (DFA) does not. However, DFA may require a larger data set for reliable results. DFA captures both short- (DFAα1) and long-term fluctuations (DFAα2). A reliable technique to measure HRV using a brief, submaximal exercise session could serve as a simple method of assessing health and adaptability. PURPOSE: To compare HRV using DFA during a 3-min steady state (SS) run versus a longer graded exercise test (GXT). METHODS: Forty recreational runners (21.1 ± 1.6 years, 27f) completed a 2-mile (3.218-km) time trial (TT) prior to, and after 18 weeks of training for a 42.2-km marathon. Subjects performed a SS run at 75% of TT velocity for 6 min followed by an incremental GXT. Paired samples t tests were used to compare pre- and post-DFA measures, TT, and VO2max, and to compare DFA scores for the final 3 min of SS with the full GXT. Delta scores were calculated for all variables. Correlations between the changes were assessed using Pearson’s RESULTS: When comparing SS and GXT, post-DFAα1 and α2 and pre-DFAα1 were different. (p ≤ 0.001). During SS, DFAα1 decreased from pre- to post-testing (0.947 ± 0.248, 0.835 ± 0.261; p ≤ 0.018) whereas DFAα2 did not change: (1.224 ± 0.188, 1.291 ± 0.207; p = 0.150). For the full GXT, neither DFAα1 or DFAα2 changed with training. Subjects improved in TT (15.5 ± 2.0, 14.3 ± 1.6; p ≤ 0.001) and VO2max (50.4 ± 7.2, 52.7 ± 7.0; p = 0.002). DFA scores for SS and GXT were significantly correlated (r = 0.59 to 0.70, p ≤ 0.001) with the exception of the DFAα2 post-test (r = 0.25, p = 0.122). The changes from pre- to post-test during SS and GXT were correlated (DFAα1: r = 0.60, p ≤ 0.001; DFAα2: r = 0.32, p = 0.044). CONCLUSION: DFAα1 during SS decreased with training, indicating increased short-term HRV. While SS and GXT yielded different DFA scores, the correlations between the scores during SS and GXT and the correlations between the changes suggest that the SS data captures information related to the larger data set. Further research is needed to determine whether the differences between SS and GXT scores are due to the smaller data set or the higher exercise intensity during GXT.

The relationship between ventilatory threshold and repeated-sprint ability in competitive male ice hockey players

Background/objectiveThe relationship between ventilatory threshold (VT1, VT2) and repeated-sprint ability (RSA) in competitive male ice hockey players was investigated. MethodsForty-three male ice hockey players aged 18–23 years competing in NCAA Division I, NCAA Division III, and Junior A level participated. Participants performed an incremental graded exercise test on a skate treadmill to determine V˙O2peak, VT1, and VT2 using MedGraphics Breezesuit™ software (v-slope). Participants performed an on-ice repeated shift (RSA) test consisting of 8-maximal skating bouts, lasting approximately 25 s and interspersed with 90 s of passive recovery, to determine first gate, second gate, and total sprint decrement (%dec). Pearson product-moment correlations and multiple regressions were used to assess relationships between ventilatory threshold variables (VT1, VT2, Stage at VT1, and Stage at VT2) and RSA (first gate, second gate, and total course decrement). ResultsStage at VT2 was the only variable substantially correlated with first gate (r = −0.35; P < 0.05), second gate (r = −0.58; P < 0.001) and total course decrement (r = −0.42; P < 0.05). ConclusionThe results of this study demonstrated that VT is substantially associated with RSA, and VT2 is more strongly correlated with RSA than V˙O2peak. This study suggests that longer duration high-intensity interval training at intensities that increase workrate at VT2 may lead to possible improvements in RSA.

Effects of detraining on breathing pattern and ventilatory efficiency in young soccer players.

This study investigated the effects of detraining on breathing pattern. The aim of this study was to evaluate the effect of a six-week detraining period on breathing patterns and ventilatory efficiency. Fourteen young soccer players were evaluated at the end of a competitive season and after a six-week detraining period. Assessment of respiratory efficiency was based on VE/VCO2 slope changes below 70% of exercise intensity. All participants underwent twice an incremental graded exercise test up to exhaustion. No differences in breathing frequency and inspiratory time/total time ratio (Ti/Ttot) were found after detraining (P>0.05). Differences in tidal volume (VT), VT/Ti quotient and VE were significant (P<0.05) at between 40 to 100% of exercise intensity. The VE/VCO2 slope did not change (P>0.05) during a postdetraining maximal incremental test. A six-week detraining period causes changes in inspiratory flow but does not affect the inspiratory time/total respiratory cycle time ratio. The overall ventilatory efficiency of the respiratory system remains constant and is not affected by detraining.

Leg compressions improve ventilatory efficiency while reducing peak and post exercise blood lactate, but does not improve perceived exertion, exercise economy or aerobic exercise capacity in endurance-trained runners

PurposeThe objective of this study was to determine if leg compressions would alter cardiorespiratory and perceived exertion measures during rest, submaximal and maximal exercise in endurance-trained runners. MethodThirteen young, endurance trained runners (10 males, 20.9±3y, 58.9±5.7mlkgmin−1) completed a randomized design, leg compressions and non-compression control condition. The incremental graded exercise test consisted of baseline rest and submaximal intensities at 23%, 70%, 75%, 85% and then a progressive increase to 100% VO2max. Running economy (RE), rating of perceived exertion (RPE), breathing rate (BR), heart rate (HR), ventilation (VE), blood lactate, VO2max and ventilatory efficiency (VE/VO2) were the primary outcome variables. ResultsRelative to the control condition, VO2 at rest, during submaximal and at max were not different. Additionally, RE, RPE, BR, and HR were similar under both conditions. Leg compressions reduced lactate at VO2max by 11% (P<0.05) and at 10min post-exercise recovery by 18% (P<0.01). Additionally, peak VE was significantly reduced in the compression condition by 8% (P<0.0001) relative to the control condition. Ventilatory efficiency was improved in compressions compared to control condition at 85 and 100% VO2max (condition×time interaction, P<0.0001). ConclusionThese data suggest that leg compressions do not alter RE, RPE, BR, HR, or VO2, during exercise. However, compressions may be beneficial for submaximal and maximal ventilatory efficiency while improving lactate clearance at VO2max and during recovery in trained runners.

Effect Of A 6-Wk Running Training Programme Using The Self-Paced VO2max Protocol In Recreational Runners

The self-paced VO2max test (SPV) has been shown to be an effective alternative to an incremental graded exercise test (GXT) in assessing maximal oxygen consumption (VO2max) in non-motorised and motorised treadmill running. However, the identification of effective training parameters has yet to be investigated. PURPOSE: This study assessed the feasibility and effectiveness of prescribing training via the SPV compared to the GXT. METHODS: Ten recreationally active males (36 ± 3 y; 1.74 ± 0.08 m; 70.0 ± 10.6 kg) and six females (26 ± 3 y; 1.66 ± 0.04 m; 58.0 ± 4.7 kg) were randomised into two training groups (GXT and SPV) and completed a 6-week training programme participating in 4 running sessions-a-week. Prior to training, participants completed 3 lab visits: SPV, GXT, and a combined Lactate Threshold (LT) and Critical Speed (CS) visit. The GXT was continuous and incremental in style, with prescribed 1 km·hr-1 increases every 2 min until the attainment of VO2max. Participants in the GXT group then completed a time-to-exhaustion (TTE) effort at velocity at VO2max (VVO2max) to determine the time for which VO2max could be maintained (Tmax). The SPV consisted of 5 x 2 min incremental stages, where running speed throughout each stage could be continuously adjusted according to five prescribed RPE levels: 11, 13, 15, 17, and maximal perception of exertion (RPE 20). The LT consisted of 1 km·hr-1 increments every 4 min until LT2 had been obtained. Participants then ran 9, 6, and 3 laps of a 400m outdoor synthetic running track to calculate CS. The training programme consisted of two interval sessions, a recovery run, and a tempo run. In the GXT group, interval training speeds were determined by Tmax, and ‘mean speed at RPE 20’ in the SPV group. VO2max, LT and CS were then retested post-training. RESULTS: In the GXT group, VO2max significantly improved following training in both the GXT (P = 0.003) and SPV (P = 0.001) tests (54.0 ± 6.0 vs. 57.5 ± 6.1 mL·kg-1·min-1 and 54.1 ± 8.3 vs. 57.4 ± 6.5 mL·kg-1·min-1, respectively). In the SPV group significant improvement was shown in the SPV (P = 0.029) (51.4 ± 5.0 vs. 55.6 ± 5.4 mL·kg-1·min-1). CONCLUSION: The present study has shown that the SPV is effective in prescribing training to improve VO2max and that ‘mean speed at RPE 20’ is an effective alternative to vVO2max as a training parameter for interval training.

Gross efficiency during flat and uphill cycling in field conditions.

While a number of studies have investigated gross efficiency (GE) in laboratory conditions, few studies have analyzed it in field conditions. Therefore, the aim of this study was to analyze the effect of gradient and cadence on GE in field conditions. Thirteen trained cyclists (mean ± SD age 23.3 ± 4.1 y, stature 177.0 ± 5.5 cm, body mass 69.0 ± 7.2 kg, maximal oxygen uptake [VO2max] 68.4 ± 5.1 mL · min-1 ·kg-1) completed an incremental graded exercise test to determine ventilatory threshold (VT) and 4 field trials of 6 min duration at 90% of VT on flat (1.1%) and uphill terrain (5.1%) with 2 different cadences (60 and 90 rpm). VO2 was measured with a portable gas analyzer and power output was controlled with a mobile power crank that was mounted on a 26-in mountain bike. GE was significantly affected by cadence (20.6% ± 1.7% vs 18.1% ± 1.3% at 60 and 90 rpm, respectively; P < .001) and terrain (20.0% ± 1.5% vs 18.7% ± 1.7% at flat and uphill cycling, respectively; P = .029). The end-exercise VO2 was 2536 ± 352 and 2594 ± 329 mL/min for flat and uphill cycling, respectively (P = .489). There was a significant difference in end-exercise VO2 between 60 (2352 ± 193 mL/min) and 90 rpm (2778 ± 431 mL/min) (P < .001). These findings support previous laboratory-based studies demonstrating reductions in GE with increasing cadence and gradient that might be attributed to changes in muscle-activity pattern.

Circulating Adiponectin Concentration and Body Composition Are Altered in Response to High-Intensity Interval Training

Adiponectin influences metabolic adaptations that would prove beneficial to endurance athletes, and yet to date there is little known about the response of adiponectin concentrations to exercise, and, in particular, the response of this hormone to training in an athlete population. This study aimed to determine the response of plasma adiponectin concentrations to acute exercise after 2 different training programs and to determine the influence of the training on body composition. Seven state-level representative rowers (age: 19 ± 1.2 years [mean ± SD], height: 1.77 ± 0.10 m, body mass: 74.0 ± 10.7 kg, VO2peak 62.1 ± 7.0 ml·kg·min) participated in the double-blind, randomized crossover investigation. Rowers performed an incremental graded exercise test before and after completing 4 weeks of high-intensity interval ergometer training and 4 weeks of traditional ergometer rowing training. Rowers' body composition was assessed at baseline and after each training program. Significant increases in plasma adiponectin concentration occurred in response to maximal exercise after completion of the high-intensity interval training (p = 0.016) but not after traditional ergometer rowing training (p = 0.69). The high-intensity interval training also resulted in significant increases in mean 4-minute power output (p = 0.002) and VO2peak (p = 0.05), and a decrease in body fat percentage (p = 0.022). Mean 4-minute power output, VO2peak, and body fat percentage were not significantly different after 4 weeks of traditional ergometer rowing training (p > 0.05). Four weeks of high-intensity interval training is associated with an increase in adiponectin concentration in response to maximal exercise and a reduction in body fat percentage. The potential for changes in adiponectin concentration to reflect positive training adaptations and athlete performance level should be further explored.

Ephedra increases VO2, impairs thermoregulation and cardiovascular function, but does not enhance exercise performance

The dietary supplement ephedra is a potent sympathomimetic that was banned by the US Food and Drug Administration in 2003 because of its deleterious effects on cardiovascular function and thermoregulation during exercise. Unfortunately, extracts of ephedra can still be obtained via the internet and are in use worldwide. The horse is the only athletic species other than humans that sweats to thermoregulate and it controls cardiovascular function in a similar fashion. The purpose of this study was to use the horse to examine the acute effects of ephedra (Ma Huang) to investigate on markers of performance as well as effects on cardiovascular function and thermoregulation during acute exercise. Six Standardbred mares (~450 kg; 6-12 years of age) were used in a crossover design consisting of a ephedra (Ma Huang containing 8% ephedra alkaloid) and control (applesauce) group. All horses performed an incremental graded exercise test (GXT) at a 6% fixed grade to measure oxygen uptake (VO2), run time, velocity at VO2max, maximal velocity, recovery time, haematocrit, total plasma protein concentration, heart rate, right ventricular pressure (RVP), pulmonary arterial pressure (PAP), rectal temperature and recovery. Measurements were recorded at rest, during exercise and post 2 and 5 min recovery. There was a difference (P&lt;0.05) in pre-exercise haematocrit but not in any other haematocrit or plasma protein sampling intervals. VO2 was greater (P&lt;0.05) for the ephedra group before exercise, at each step of the GXT, at VO2max, and during recovery compared to the control group. Recovery time was significantly different, but run time was not (P≯0.05). Heart rate was elevated (P&lt;0.05) at 2 and 5 min recovery in horses administered ephedra. Significant differences were observed for RVP and PAP and rectal temperature during recovery. Recovery score (sweating response, respiration rate, behaviour) was altered (P&lt;0.05) by ephedra administration. These data suggests an increase in energy expenditure and thermogenesis when horses consume ephedra. However, markers of performance (run time, velocity at VO2max, and maximal velocity completed) were not altered by ephedra administration.

The effect of estimation and production procedures on running economy in recreational athletes

ObjectivesRunning economy is an important component in any endurance event. However, the influence of effort perception on running economy has yet to be examined. DesignThe purpose of this study was to assess the oxygen cost of running (running economy) at identical ratings of perceived exertion (RPE) during estimation (EST) and production (PR) procedures, during treadmill exercise. MethodsFourteen, well-trained male participants actively produced (self-regulated) a range of submaximal exercise intensities equating to RPE values 9, 11, 13, 15 and 17, and passively estimated their perception of exertion during an incremental graded-exercise test (GXT). Allometric scaling was used to ensure an appropriate comparison in running economy between conditions. ResultsThe present study demonstrated that the overall running economy between conditions was statistically similar (p>0.05). A significant interaction was however identified between Conditions and RPE (p<0.001). The interaction revealed that running economy significantly improved during PR but remained fairly consistent during EST between moderate and high perceptions of exertion (RPE 11–17). Despite similarities in running economy between conditions, physiological (oxygen uptake, heart rate, minute ventilation and blood lactate) and physical (running velocity) markers of exercise intensity were significantly higher during EST for equivalent perceptions of exertion (all p<0.05). ConclusionsPassive estimation procedures may improve running economy and enhance athletic performance when compared to identical perceptions of exertion elicited during active production procedures. Athletes, coaches and physical trainers should consider the perceptual procedures utilised during training to ensure that an athlete trains at the most effective training intensity.

Immune function changes of rats in incremental graded exercise test

This study evaluated the effect of incremental graded exercise on immune function of spleen and thymus in rats. The animals were divided into 6 groups, with 32 animals in per group: no exercise (W0), exercise for 1 week (W1), exercise for 2 weeks (W2), exercise for 3 weeks (W3), exercise for 4 weeks (W4) and exercise for 5 weeks (W5). Each group was further divided into 4 groups, with 8 animals in per group: sedentary (S), no recovery after exercise (AE0), recovery for 3 h after exercise (AE3), and recovery for 24 h after exercise (AE24). Incremental graded exercise test was performed on a rodent treadmill (gradient of 0°), which lasted for 5 weeks. The rats were motivated to exercise for 30 min a day for 6 days a week and weekend breaks. Speed in the treadmill gradually increased to 5 (W0), 20 (W1), 25 (W2), 30 (W3), 35 (W4) and 40 m/min (W5). At the end of exercise, the rats were killed, and thymus and spleen tissue were collected and weighed. The results showed that incremental exercise affected the immune function of spleen and thymus. With the incremental implementation and extension of exercise time, the effect of exercise on spleen index and thymus index became increasingly greater. Key words: Incremental graded exercise, immune function, spleen index, thymus index rats.

Maximal aerobic capacity (VO2max) in horses: a retrospective study to identify the age-related decline

Previous studies of the effect of age on maximal aerobic capacity (maximal rate of oxygen consumption, VO2max) in horses have only grouped horses (young, middle-aged and old) for statistical analysis. Those experiments were not designed to determine a break point due to age. The purpose of this study was to utilize data collected over the last 15 years to test the nature of the association between age and VO2max, and secondarily, to determine whether there is a ‘breakpoint’ in the age-related decline in aerobic capacity. Data were acquired from 50 unfit Standardbred mares ranging in age from 4 to 29 years, and were used in a retrospective regression analysis in order to characterize the age-related decline in VO2max. All VO2max values were measured using the same incremental graded exercise test protocol. The data were analyzed using a curvilinear regression analysis predicting VO2max from age, and the break point was determined using univariate simple contrasts. There was a significant decline in VO2max with age (R2 = 0.554; P &lt; 0.001). The data analysis demonstrated a notable downturn in cardiopulmonary function between the ages of 18 and 20 years (P &lt; 0.001). Such results indicate similar responses to age between humans and horses. These results have implications for improving training methods in active older horses.

Effect of orange peel and black tea extracts on markers of performance and cytokine markers of inflammation in horses

AbstractThis study tested the hypothesis that orange peel (O) and decaffeinated black tea (T) extracts would alter markers of exercise performance as well as exercise-induced mRNA expression for the inflammatory cytokines IL-6, TNF-alpha and IFN-gamma. Nine healthy, unfit Standardbred mares (age: 10±4years, ∼450kg) were assigned to three treatment groups in a randomized crossover design where each horse was administered one of the following; placebo (O; 21 water), black tea extract in water (T; 21) or orange peel extract in water (W; 21), via a nasogastric tube. One hour later the horses completed an incremental graded exercise test (GXT) on a treadmill at a fixed 6% grade with measurements and blood samples obtained at rest, at the end of each 1min step of the GXT and at 2 and 5min post-GXT. An additional set of blood samples for Polymerase Chain Reaction (PCR) measurements of mRNA was obtained before exercise and at 5 and 30min and 1, 2, 4 and 24h post-GXT. The GXTs were conducted between 0700 and 1200h not less than 7days apart. There were no differences (P&gt;0.05) in VO2max, respiratory exchange ratio, run time, velocity at VO2max, core body temperature, haematocrit, creatine kinase (CK), plasma lactate concentrations, HR, right ventricular pressure (RVP) or pulmonary artery pressure (PAP) across treatments. A major finding was that orange peel extract significantly reduced post-exercise VO2 recovery time (W = 112±7, O = 86±6, and T = 120±11s). There was a significant difference in plasma total protein concentration (TP) in the O runs compared with water and T. TNF-alpha mRNA expression was lower in the T runs compared with water and O trials. IFN-gamma mRNA expression levels appeared to be lower in both the T and O extract runs compared with the water trials. The mRNA expression of IL-6 was unaltered across treatment groups. These data suggest that orange peel and black tea extracts may modulate the cytokine responses to intense exercise. Orange peel extract reduced post-exercise recovery time and may potentially enhance the ability of horses to perform subsequent bouts of high-intensity exercise.

Sport specific performance diagnosis in rowing: an incremental graded exercise test in coxless pairs.

The aim of the present study was to develop and validate an incremental graded exercise test performed in the rowing boat(coxless pair) in order to give specific performance evaluation data. Furthermore, an attempt was made to transfer these data to training recommendations. Thirty-four female rowers of national and international level performed a 4 x 6 min incremental graded exercise test GXT(boat) in coxless pairs on a lake (6 km, no wind, no waves). The boat velocity on the water (V; measured by a speedometer PACE COACH) was increased continuously from 3.55 m x s-I to 4.03 m x s-1. The individual anaerobic threshold(IAT) was determined by means of the lactate (LA) kinetics during and after exercise. Within 28 days all subjects performed arowing ergometry test GXT(ergo); Gjessing rowing ergometer: 40 watts increments every 3 min) as well as 70 min of constant endurance training in the boat in moderate velocity (ET; n- 10 pairs because of changing weather conditions). Results for V/LAIHR at IAT are: GXT(boat): 3.84+/- 0.10 m x s-1/2.44 +/- 0.66 mmol x 1-1/172 + 11 min(-1); GXT(ergo): 206+/-10 watts/2.53 +0.40 mmol x 1-171 +/- 10 min-' (means+/-SD). The Spearman rank order test showed significant correlations for HR (p < 0.001) and the mean performances of the coxless pairs (p < 0.05). A'5 % lower V during ET lead to a 10% lower HR and a 30% lower LA compared to the values at IAT. In conclusion, both a performance specific evaluation and velocity oriented control of training are possible by means of a 4 x 6 min incremental graded exercise test in coxlesspairs. However, this test on the water requires almost perfect weather conditions. The HR recommendations based on GXT (ergo) were confirmed during GXT(boat).

Prediction of peak oxygen uptake in chronic fatigue syndrome.

OBJECTIVES: To establish a simple, valid, and acceptable method of predicting peak oxygen uptake (VO2peak) in patients with chronic fatigue syndrome (CFS), which could provide a basis for subsequent exercise...

Prediction of peak oxygen consumption in patients with intermittent claudication.

Determination of peak oxygen consumption (VO2peak) is considered important for assessing a patient's functional capacity and for exercise prescription. However, the equipment necessary to obtain accurate determination of VO2peak is not always available in clinical settings. The present study sought to develop an equation to estimate VO2peak in peripheral arterial occlusive disease (PAOD) patients with intermittent claudication and to determine independent predictors of VO2peak in this population. One hundred and fifty-seven patients with intermittent claudication were assigned to either a validation group (n = 105) or a cross-validation group (n = 52). Medical history, height, weight, body mass index (BMI), age, gender, smoking status, resting and postexercise ankle/brachial systolic pressure index (ABI), and time to maximal claudication pain and maximal heart rate from an incremental graded exercise test (GXT) were used as potential independent predictors of VO2peak. Time to onset of maximal claudication pain, maximal heart rate, and BMI were all independently associated with VO2peak. These variables were used to estimate VO2peak by the following equation: VO2peak (mL/kg/min) = (0.00872 x maximal claudication pain time [sec]) + (0.02839 x maximal heart rate [b/min]) - (0.12034 x BMI) + 10.11411 r = 0.71, r2 = 0.50, standard error of estimate = 2.02 mL/kg/min, p < 0.0001There was no significant difference between the estimated and actual VO2peak in the cross-validation group, and the coefficient of variation between estimated and actual VO2peak in this group was 18.3%. There was no significant difference between the correlation coefficient for the relationship between estimated and actual VO2peak in the cross-validation group (r = 0.61) and the multiple correlation coefficient from the validation group (r = 0.71). Results of this study suggest that a multiple regression equation can be used to estimate VO2peak in patients with intermittent claudication by measuring time to maximal claudication pain and maximal heart rate from a GXT and by measuring BMI.