Incremental Treadmill Protocol Research Articles

Differences in Physical Indexes between Football Players of Different Playing Positions and Correlation to the Weekly Training Load

The aim of this study was twofold: (a) to examine the differences on physical indexes between players of different playing positions and (b) to reveal the correlations between their physical parameters and the running profile within the weekly microcycles. The subjects (n = 44) were separated into five positions: central defenders (n = 7), wide defenders (n = 9), midfielders (n = 13), wingers (n = 8) and strikers (n = 7), and all of them belonged to a professional 1st division European team during the 2020–21 and 2021–22 seasons. An incremental treadmill protocol was used to assess the VO2max, vVO2max and the vRER in the last week before the regular season. Then, during the first semesters, external load data were collected for two consecutive seasons to analyze the running profiles of the different positions. There were no differences on physical parameters between the players of various positions, but interestingly there were different correlations with the external load during the microcycles. Central defenders did not show any correlation. For the other positions, correlations were found between respiratory exchange ratio (vRER) and metabolic power efforts (MPWEF) (p = 0.028, r = 0.721) for wide defenders, between vRER and medium intensity accelerations (ACC2) (p = 0.004, r = 0.741) for midfielders, medium intensity decelerations (DEC2) (p = 0.01, r = 0.685), metabolic power zone 5 (MPW5) (p = 0.016, r = 0.652), MPWEF (p = 0.005, r = 0.725), and also between maximal rate of oxygen consumption (VO2max) and high intensity decelerations (DEC3) (p = 0.045, r = 0.564), metabolic power zone 4 (MPW4) (p = 0.026, r = 0.614), MPW5 (p = 0.017, r = 0.646), MPWEF (p = 0.01, r = 0.685). A correlation between velocity on VO2max (vVO2max) and ACC2 (p = 0.038, r = 0.733), MPW5 (p = 0.005, r = 0.873), and MPWEF (p = 0.009, r = 0.84) was found for the wingers. Finally, there was a correlation between vRER and MPWEF (p = 0.026, r = 0.866), and between vVO2max and high intensity accelerations (ACC3) (p = 0.03, r = 0.801) for the strikers. Our study supports that the external load of players in different positions during the training sessions is correlated with their physical indexes. These correlations are determined mostly by their tactical role, but not from their physical level, as there were no differences.

The effects of wearing face masks on the perception and mood of male healthy male adults during treadmill running: A pilot study.

In the past few years, the face mask has been recommended for the prevention of exposing others to COVID-19. Wearing a face mask may have the potential to increase dyspnea and discomfort during exercise; however, controversy exists on whether wearing face masks during exercise affects exercise performance, perception, and mood in runners. We investigated the physiological and perceptual responses of healthy male adults who had experienced long-distance running while exercising at different intensities. Nine healthy young adults who were long-distance runners wearing surgical face mask conducted an incremental treadmill protocol. The protocol was three 6-min stages (20%, 40%, and 60% of maximal heart rate, respectively). The rating of perceived exertion (RPE) and the feeling scale (FS) were measured. RPE was higher in mask condition than in unmask condition (No mask vs. Face mask, light; 8.22 vs. 8.78, p = 0.615, middle; 10.00 vs. 10.78, p = 0.345, high; 12.33 vs. 13.67, p = 0.044.), while FS was not different between conditions. The present study shows that wearing a mask may increase rating of perceived exertion and discomfort when the exercise intensity exceeds a certain threshold in healthy male adults who have experienced long-distance running.

Assessment of Intercostal Muscle Near-Infrared Spectroscopy for Estimating Respiratory Compensation Point in Trained Endurance Athletes.

This study aimed to assess the reliability and validity of estimating the respiratory compensation point (RCP) in trained endurance athletes by analyzing intercostal muscles' NIRS-derived tissue oxygenation dynamics. Seventeen experienced trail runners underwent an incremental treadmill protocol on two separate occasions, with a 7-day gap between assessments. Gas exchange and muscle oxygenation data were collected, and the oxygen saturation breakpoint (SmO2BP) measured in the intercostal muscles was compared to the RCP, which was identified by the increase in the VE/V.CO2 slope and the point at which the PetCO2 started to decrease. No statistically significant differences were observed between the two methods for any of the variables analyzed. Bland-Altman analysis showed significant agreement between the NIRS and gas analyzer methods for speed (r = 0.96, p < 0.05), HR (r = 0.98, p < 0.05), V.O2 relative to body mass (r = 0.99, p < 0.05), and %SmO2 (r = 0.98, p < 0.05). The interclass correlation coefficient values showed moderate to good reliability (0.60 to 0.86), and test-retest analysis revealed mean differences within the confidence intervals for all variables. These findings suggest that the SmO2BP measured using a portable NIRS device in the intercostal muscles is a reliable and valid tool for estimating the RCP for experienced trail runners and might be useful for coaches and athletes to monitor endurance training.

Abstract 12906: Exercise Training Protects Against Ischemic Muscle Damage in a Large-Animal Model of Peripheral Artery Disease

Peripheral artery disease (PAD) causes an ischemic myopathy in the lower extremity muscles, which contributes to patient functional disability. Although structured exercise therapy is a leading therapeutic to improve ambulatory function, the impact of exercise on PAD myopathy is unclear. Using our porcine model of PAD, we sought to elucidate the effect of hindlimb ischemia on markers of 1) muscle damage (caspase 3, myogenic differentiation 1 (MyoD), and Forkhead box protein O1 (FOXO1)), 2) muscle protein turnover (autophagic flux and proteolytic activity), and 3) whether these indices were altered with exercise training. Methods: Seven Yorkshire swine were exposed to right hindlimb ischemia by endovascular external iliac artery occlusion. Following ischemia onset, the swine were divided into 2 training groups: supervised exercise trained (ET) (n=4) and sedentary controls (SED) (n=3). ET pigs followed an incremental treadmill protocol 3 times weekly for 4 weeks. SED pigs had standard ambulation. The tibialis anterior from ischemic and non-ischemic limbs was excised after animal termination. Markers of muscle damage and proteolytic activity were assessed via RT-PCR and enzymatic activity kits, respectively. The ratio of intramuscular microtubule-associated protein light chain 3 (LC3)-II:LC3-I, as well as sequestosome (p62), and mitofusion2 (MFN2) content from immunoblots were used to monitor autophagic flux. Results: Gene expression of intramuscular damage was significantly higher in SED ischemic muscle compared to ET muscle (caspase 3 (SED: 5.59±1.5; ET: 1.67±1.5), MyoD (SED: 4.55±1.2; ET: 1.24±1.5) and FOXO1 (SED: 1.74±0.5; ET: 1.07±1.1), p&lt;0.0001). Moreover, ischemic muscle from ET pigs showed no alteration in markers of muscle damage when compared to the SED and ET non-ischemic conditions (p&gt;0.05). Although proteolytic activity was unaltered (p&gt;0.05), autophagic flux tended to be increased in ET ischemic muscle (LC3-II:LC3-I ratio (ET: 0.21±0.1; SED: 0.10±0.1 AU, p=0.099), p62 (ET: 15.80±5.1; SED: 7.75±2.8 AU, p=0.068) and MFN2 (ET: 42.72±15.9; SED: 16.82±11.3 AU, p=0.214). Conclusions: These data suggest exercise therapy is protective against ischemic muscle damage and may improve muscle quality via accelerating autophagic flux.

Effect of a Prolonged Maximal Bout of Exercise on Visual Performance

Background: Despite it being purported that acute, prolonged maximal periods of exercise may impair visual performance, little/no research on this topic is forthcoming. In fact, research has demonstrated that sub-maximal and maximal acute exercise may actually improve cognitive and sensory tasks and thus possibly improve visual performance. Objectives: This study aimed to ascertain the influence of an acute, prolonged maximal bout of exercise on visual performance. Methods: A quantitative study was undertaken with 60 untrained males being divided into a control group (CON; n = 30) or treatment group (TRE; n = 30). Both groups completed a baseline vision test battery consisting of accommodation facility, saccadic eye movement, speed of recognition, peripheral awareness, visual memory, and hand-eye coordination using the following tests; Hart Near Far Rock, saccadic eye movement, evasion, accumulator, flash memory and Ball Wall Toss tests. Two weeks later, participants returned for follow-up testing using the same vision test battery, with the TRE participants first engaging in a standardized incremental maximal treadmill protocol immediately prior to their vision testing. Results: Following the incremental maximal treadmill protocol, statistical analyses indicated that statistically significant (P ≤ 0.05) differences existed for accommodation facility, saccadic eye movements, speed of recognition, hand-eye coordination, peripheral awareness, and visual memory between pre-test and after the aerobic treatment (P = 0.00 for all measures). Conclusions: This study indicates that an acute, prolonged maximal bout of running improves visual performance. As such, an appropriate prolonged maximal warm-up may be required as opposed to a standardized and general warm-up when preparing an athlete for visual skills training or for participation in an athletic event that requires optimal visual performance.

A Transparent Method for Step Detection using an Acceleration Threshold.

Step-based metrics provide simple measures of ambulatory activity, yet device software either includes undisclosed proprietary step detection algorithms or simply do not compute step-based metrics. We aimed to develop and validate a simple algorithm to accurately detect steps across various ambulatory and non-ambulatory activities. Seventy-five adults (21-39 years) completed seven simulated activities of daily living (e.g., sitting, vacuuming, folding laundry) and an incremental treadmill protocol from 0.22-2.2ms-1. Directly observed steps were hand-tallied. Participants wore GENEActiv and ActiGraph accelerometers, one of each on their waist and on their non-dominant wrist. Raw acceleration (g) signals from the anterior-posterior, medial-lateral, vertical, and vector magnitude (VM) directions were assessed separately for each device. Signals were demeaned across all activities and bandpass filtered [0.25, 2.5Hz]. Steps were detected via peak picking, with optimal thresholds (i.e., minimized absolute error from accumulated hand counted) determined by iterating minimum acceleration values to detect steps. Step counts were converted into cadence (steps/minute), and k-fold cross-validation quantified error (root mean squared error [RMSE]). We report optimal thresholds for use of either device on the waist (threshold=0.0267g) and wrist (threshold=0.0359g) using the VM signal. These thresholds yielded low error for the waist (RMSE<173 steps, ≤2.28 steps/minute) and wrist (RMSE<481 steps, ≤6.47 steps/minute) across all activities, and outperformed ActiLife's proprietary algorithm (RMSE=1312 and 2913 steps, 17.29 and 38.06 steps/minute for the waist and wrist, respectively). The thresholds reported herein provide a simple, transparent framework for step detection using accelerometers during treadmill ambulation and activities of daily living for waist- and wrist-worn locations.

Effect of Wearing Surgical Face Masks During Exercise: Does Intensity Matter?

Face masks are widely recommended as means of controlling the coronavirus disease outbreak. This study aimed to examine the physiological and perceptual responses of wearing surgical face masks while exercising at different intensities. Thirteen healthy young adults (mean age, 21.9 ± 1.4 years) conducted randomized crossover trials with or without a surgical face mask. In each trial, participants completed an incremental treadmill protocol, with three 6-min stages (light, moderate, and vigorous at 25, 50, and 75% maximal oxygen uptake, respectively). Physiological outcomes (heart rate, blood lactate, and oxygen saturation level), perceived exertion and discomfort feeling were assessed. No significant differences were observed in physiological outcomes with or without masks at different exercise intensities (p > 0.05). However, the rating of perceived exertion (RPE) was significantly higher when exercising vigorously (mask: 15.5 ± 1.5 vs. no-mask: 14.2 ± 2.1, p < 0.05). Participants wearing masks reported marked discomfort, such as feeling hot, humid, and breathing resistance. Although face mask-wearing during exercise may not have detrimental effects on major physiological parameters, it can increase perceived exertion level and discomfort when the exercise intensity exceeds a certain threshold. Therefore, healthcare professionals should cautiously evaluate each person’s ability to exercise while wearing a mask and tailor their prescription accordingly.

Body fat content correlates with maximum aerobic capacity in healthy sedentary Indian males

BackgroundObesity is a multifactorial public health problem with varying effects on physical fitness determined by maximum aerobic capacity or VO2max. The relationship between body fat content and VO2max has shown varying results. The present study was planned as an experimental study to evaluate the relationship between body fat content and maximum aerobic capacity. Methods104 healthy Indian males [Age: 21 (4.87)years; Height: 171.4 (6.14)cm; Weight: 64.1 (8.57)kg] were evaluated for body fat content using body mass index (BMI), bioimpedance, skinfold thickness (SFT), body girth (BG) measurements, waist circumference (WC), and waist-hip ratio (WHR). Maximum aerobic capacity or VO2max for all subjects was determined indirectly from maximum heart rate achieved using an incremental treadmill protocol using Astrand and Astrand nomogram. ResultsVO2max, when expressed in L/min, showed a statistically significant positive correlation with body fat irrespective of the method of estimation. VO2max, when expressed in ml/kg/min, showed negative correlation with five of the seven clinical parameters of fat estimation. Of these, a statistically significant negative correlation was seen with SFT. ConclusionVO2max (L/min) shows a significant positive correlation with all methods of body fat estimation. VO2max (ml/kg/min) shows a significant negative correlation with skinfold thickness. Monitoring of body fat content using skinfold thickness could be studied further for its use in the early identification of young, healthy adult Indian males with low aerobic fitness.

Association of Fitness Level Early in Pregnancy with Compliance Toward an Exercise Intervention Throughout Gestation in Obese Women

Abstract Objectives Low participant compliance with prenatal exercise trials can result in loss of power to detect intervention effects. The objective of this study was to assess the association of aerobic capacity at enrollment with compliance with an exercise intervention throughout gestation. Methods Fifty-nine sedentary women with obesity who participated in the exercise arm of a randomized controlled trial were assessed at gestation week 12, and compliance was monitored throughout gestation. Fat-free mass index (FFMI, kg/m2) was obtained by DXA and measured height. Submaximal VO2 (Borg score of 15) was measured using an incremental treadmill protocol. VO2 was normalized to FFMI (ml·min−1· FFMI−1). A VO2 cutoff of ≥112.7 (Q3 to highest data point) or ≤69.4 (Q1 to smallest data point) was used to classify women as “High” (n = 17) or “Low” (n = 17) fitness. Compliance (%) was estimated using the date of first exercise and delivery date, assuming a goal of 3 exercise sessions per week. Education level and birth weight were self-reported, whereas gestational weight gain (GWG), and gestational age (GA) were calculated. Results Groups were similar in BMI and LBMI at enrollment. The proportion of women with a college degree differed between groups (High = 100% vs. Low = 29%, P &amp;lt; .0001), and there was interaction between baseline fitness level (VO2) and education level (P = 0.004) in predicting compliance to the exercise intervention. For women with a college degree, there was no difference in compliance between high and low fitness groups (72 ± 5% vs. 60 ± 10%, P = NS). However, compliance was lower in women in the Low group with high school degree than in women in the High group (52 ± 6% vs.72 ± 5%, P = 0.0244). There were no impact of education on compliance for the low fitness group. GWG, GA and birth-weight were similar between groups (P = NS). Conclusions In these preliminary analyses, there was an interaction between fitness and education level on compliance with a prenatal exercise intervention. Compliance was about 20 percentage points lower in women with lower fitness and lower education when compared to women with higher fitness and higher education at enrollment. Funding Sources USDA-ARS Project 6026–51,000-012–06S.

Validation of Maximal, Submaximal, and Nonexercise Indirect [Formula: see text]O2max Estimations at 2600 m Altitude.

Aim: To study the criterion validity of three indirect maximal oxygen uptake ([Formula: see text]O2max) assessment equations at altitude. Methods: We studied 64 young adults (53% men) at Bogota, Colombia (2600 m altitude). Direct [Formula: see text]O2max was measured by indirect calorimetry using a maximal incremental treadmill protocol. Indirect [Formula: see text]O2max was estimated by two exercise field tests (the 20-m shuttle-run test [20-MST] and the 2-km walking test (UKK)) and one nonexercise method (the perceived functional ability-physical activity rating questionnaire [PFA-PAR]). Altitude-adjusted PFA-PAR was estimated as a 13% linear reduction in PFA-PAR. We calculated Lin concordance coefficients (LCC) and standard error of the estimates (SEEs), and we performed Bland-Altman analyses for each indirect method. Results: Mean [Formula: see text]O2max was 41.2 ± 5.8 mL/kg/min in men and 32.2 ± 3.6 mL/kg/min in women. We found the highest agreement with direct [Formula: see text]O2max for the 20-MST (LCC = 0.79, SEE = 3.91 mL/kg/min), followed in order by the altitude-adjusted PFA-PAR (LCC = 0.71, SEE = 4.12 mL/kg/min), the UKK (LCC = 0.67, SEE = 5.48 mL/kg/min), and the unadjusted PFA-PAR (LCC = 0.57, SEE = 4.75 mL/kg/min). The unadjusted PFA-PAR tended to overestimate [Formula: see text]O2max, but Bland-Altman analysis showed that this bias disappeared after altitude adjustment. Conclusion: Several maximal, submaximal, and nonexercise methods provide estimates of [Formula: see text]O2max with acceptable validity for use in epidemiological studies of populations living at moderate altitude.

Limitations To v̇O2max In Competitive Swimmers

PURPOSE: Literature containing V̇O2MAX values for competitive swimmers is sparse and has generally reported modest values for competitive swimmers when compared with other endurance athletes. The purpose of this investigation was 1) to pool the findings of previous research to provide a reference value for the V̇O2MAX of competitive swimmers and 2) to examine primary data to suggest a basis for the modest values reported to date. METHODS: Values obtained from the literature from swimmers age 17 years or older described as “trained,” “highly-trained,” “collegiate,” “national-level,” “international-level,” or “elite,” and completing incremental, open-flow, indirect calorimetry swimming protocols were included in the analysis. A mean and 95% CI were calculated for each sex using a random-effects model. Additionally, in our laboratory, swimming V̇O2MAX data were collected on national- and international-level women and men swimmers in a swimming flume using a continuous, incremental weight-loading protocol at a constant speed. These data were compared to V̇O2MAX data from national-level runners (7 men) who completed an incremental grade increase treadmill protocol in our lab. RESULTS: Eight articles utilizing swimming protocols (k = 9, n = 70 women; k = 13, n = 121 men) were analyzed. The relative V̇O2MAX (mL·kg-1·min-1; mean ± 95% CI) was 50.2 ± 1.3 for women and 54.9 ± 0.5 for men. Our V̇O2MAX data (4 women; 10 men) agree with the literature values (mean ± SD; 51.0 ± 5.0 women; 53.6 ± 4.7 men). There was a strong (r = 0.75) and significant (p = 0.01) correlation between breathing frequency (fb; breaths·min-1) at max and relative V̇O2MAX in the men swimmers that was not evident in the running cohort (r = -0.41; p = 0.34). Relative V̇O2MAX, minute ventilation (V̇E, BTPS; L·min-1), and fb at max were significantly different (p < 0.01; p < 0.01; p = 0.01) between men swimmers (V̇E, BTPS = 135.7 ± 16.1; fb = 47.1 ± 9.1) and runners (V̇O2MAX = 73.9 ± 3.5; V̇E, BTPS = 169.7 ± 16.6; fb = 58.6 ± 7.6). CONCLUSIONS: The relationship between fb and V̇O2MAX in swimmers suggests that V̇O2MAX for competitive swimmers could be compromised at least in part by fb and presumably V̇E by extension. The absence of this same relationship in runners suggests that this could be due to constraints specific to swimming, such as phase-locked breathing.

An Occupational-Specific O2max Protocol for Structural Firefighters.

The aim of this study was to validate a (Equation is included in full-text article.)O2max protocol designed specifically for the occupational demands of firefighters by incorporating the use of personal protective equipment (PPE). Career firefighters completed a stage-graded exercise test (GXT) with submaximal square-wave verification bout while wearing PPE (pants and boots) to determine (Equation is included in full-text article.)O2max. Using the self-reported Physical Activity-Rating (PA-R) scale and an estimated nonexercise regression equation of (Equation is included in full-text article.)O2max for comparison to measured. Twenty-eight male, career firefighters performed the GXT and square-wave bout. (Equation is included in full-text article.)O2 values (mean ± SD) from the GXT and the square-wave verification bout were 41.04 ± 6.98 and 39.74 ± 6.42 mL/kg/min, respectively (ICC = 0.98, typical error = 0.96 mL/kg/min, CV = 2.4%). Our data suggest an incremental treadmill protocol that incorporates PPE and square-wave verification as an occupational-specific tool to measure cardiovascular fitness in firefighters.

PeakVO2-cardiac Output Relationship During Exercise In Seniors Who Are Sedentary, Athletic, And HFpEF Patients

PURPOSE: The purpose of this study was to evaluate the relationship between O2 uptake (VO2) and cardiac output (Qc) during exercise in seniors who were sedentary, athletic, and Patients with HFpEF. METHODS: Based on lifestyle physical activity level categorization, elderly-sedentary seniors (n=27, 69±5 yrs) and elderly-athletic seniors (n=25, 68±3 yrs), and patients with heart failure with preserved ejection fraction (HFpEF) (n=24, 71±7 yrs) were selected and underwent cardiopulmonary exercise testing. A modified Astrand-Saltin incremental treadmill protocol was performed to determine VO2 and ventilatory gas exchange using the Douglas bag technique. Cardiac output (Qc) was measured with the C2H2 rebreathing method. Peak arterial-venous O2 difference (peak AV-O2 diff) was calculated by Fick equation (peak VO2 divided by peak Qc). The slope of the relationship between changes in VO2 and Qc during exercise was calculated by [INCREMENT]Qc/[INCREMENT]VO2. RESULTS: Peak VO2 and peak Qc was lower in HFpEF group than the other groups (peak VO2: HFpEF: 13.1±3.6; vs. Sedentary: 23.5±4.4; vs. Athlete: 39.5±5.3 ml/kg/min, P<0.001 (ANOVA) as was peak Qc: HFpEF: 12.7±4.1; vs. Sedentary: 14.8±4.1; vs. Athlete: 19.0±6.0 L/min, P<0.001 (ANOVA)). Peak AV-O2 diff in HFpEF group was the smallest in the 3 groups (HFpEF: 9.7±2.3; vs. Sedentary: 12.2±3.0; vs. Athlete: 14.3±3.6 %, P<0.0001 (ANOVA)), and the Athlete group was greater than the Sedentary group (P=0.04 (Wilcoxon rank-sum)). The relationship between Qc and VO2 (slope of [INCREMENT]Qc/[INCREMENT]VO2) is shown in Figure. CONCLUSIONS: Both reduced Qc and AV-O2 diff contribute significantly to the impairment of exercise capacity in HFpEF through Qc is augmented for a given VO2. Lifelong exercise training enhances Qc and peak AV-O2 diff in the elderly population and normalizes Qc/VO2 relationship.Figure

Physiological Responses During the Time Limit at 100% of the Peak Velocity in the Carminatti's Test in Futsal Players.

The aim of this study was to investigate the physiological responses during the time limit at the intensity of the peak velocity of the Carminatti’s test (T-CAR). Ten professional futsal players (age, 27.4 ± 5.8 years, body mass, 78.8 ± 8.5 kg, body height, 175.8 ± 6.8 cm, body fat mass, 14.1 ± 2.6%) took part in the study. The players performed three tests, with an interval of at least 48 hours, as follows: the T-CAR to determine the peak velocity and the maximal heart rate; an incremental treadmill protocol to determine the maximal physiological responses; and a time limit running test at the peak velocity reached in the T-CAR. During the last two tests, a portable gas analyzer was used for direct measurement of cardiorespiratory variables. It was shown that the peak velocity was not significantly different from the maximal aerobic speed achieved in the laboratory (p = 0.213). All athletes reached their maximum oxygen uptake during the time limit test. The maximum oxygen uptake achieved during the time limit test was not different from that observed in the laboratory condition (51.1 ± 4.7 vs. 49.6 ± 4.7 ml·kg-1·min-1, respectively, p = 0.100). In addition, Bland and Altman plots evidenced acceptable agreement between them. On average, athletes took ~140 s to achieve maximum oxygen uptake and maintained it for ~180 s. Therefore, the peak velocity intensity can be used as an indicator of maximal aerobic power of futsal athletes and the time limit can be used as a reference for training prescription.

Assessment of Maximum Aerobic Capacity and Anaerobic Threshold of Elite Ballet Dancers.

An athlete's cardiorespiratory profile, maximal aerobic capacity, and anaerobic threshold is affected by training regimen and competition demands. The present study aimed to ascertain whether there are company rank differences in maximal aerobic capacity and anaerobic threshold in elite classical ballet dancers. Seventy-four volunteers (M 34, F 40) were recruited from two full-time professional classical ballet companies. All participants completed a continuous incremental treadmill protocol with a 1-km/hr speed increase at the end of each 1-min stage until termination criteria had been achieved (e.g., voluntary cessation, respiratory exchange ratio <1.15, HR ±5 bpm of estimated HRmax). Peak VO2 (5-breathe smooth) was recorded and anaerobic threshold calculated using ventilatory curve and ventilatory equivalents methods. Statistical analysis reported between-subject effects for gender (F1,67=35.18, p<0.001) and rank (F1,67=8.67, p<0.001); post hoc tests reported soloists (39.5±5.15 mL/kg/min) as having significantly lower VO2 peak than artists (45.9±5.75 mL/kg/min, p<0.001) and principal dancers (48.07±3.24 mL/kg/min, p<0.001). Significant differences in anaerobic threshold were reported for age (F1,67=7.68, p=0.008) and rank (F1,67=3.56, p=0.034); post hoc tests reported artists (75.8±5.45%) having significantly lower anaerobic threshold than soloists (80.9±5.71, p<0.01) and principals (84.1±4.84%, p<0.001). The observed differences in VO2 peak and anaerobic threshold between the ranks in ballet companies are probably due to the different rehearsal and performance demands.

Influence of oxygen uptake kinetics on physical performance in youth soccer.

To examine the relationship between oxygen uptake kinetics (VO2 kinetics) and physical measures associated with soccer match play, within a group of highly trained youth soccer players. Seventeen highly trained youth soccer players (age: 13.3±0.4year, self-assessed Tanner stage: 3±1) volunteered for the study. Players initially completed an incremental treadmill protocol to exhaustion, to establish gaseous exchange threshold (GET) and VO2max (59.1±5.4mLkg(-1)min(-1)). On subsequent visits, players completed a step transition protocol from rest-moderate-intensity exercise, followed by an immediate transition, and from moderate- to severe-intensity exercise (moderate: 95% GET, severe: 60%∆), during which VO2 kinetics were determined. Physical soccer-based performance was assessed using a maximal Yo-Yo intermittent recovery test level 1 (Yo-Yo IR1) and via GPS-derived measures of physical soccer performance during soccer match play, three 2×20min, 11 v 11 matches, to gain measures of physical performance during soccer match play. Partial correlations revealed significant inverse relationships between the unloaded-to-moderate transition time constant (tau) and: Yo-Yo IR1 performance (r=-0.58, P=0.02) and GPS variables [total distance (TD): r=-0.64, P=0.007, high-speed running (HSR): r=-0.64, P=0.008 and high-speed running efforts (HSReff): r=-0.66, P=0.005]. Measures of VO2 kinetics are related to physical measures associated with soccer match play and could potentially be used to distinguish between those of superior physical performance, within a group of highly trained youth soccer players.

Interval TRIMP Scores Predict Improvement in Maximal Oxygen Consumption in middle-aged, sedentary Individuals

PURPOSE: The optimal training strategy to maximize increases in VO2 max is unclear. We sought to compare the contribution of different training loads from an exercise program combining interval and continuous training on improvements in VO2 max. Training load was objectively quantified by the Training Impulse (TRIMP). METHODS: We studied 30 healthy sedentary participants (53.21±4.70 years, 14 males). Each participant was prescribed a progressive exercise prescription consisting of endurance and interval training. Between month 1 and 6, the exercise progressed to reach a peak phase, which was maintained for 3 months (weekly prescription: interval x2; one 60 min base pace; one 30 min base pace; one recovery). VO2max was measured at baseline and after completion of the peak phase of training via Douglas Bag method and incremental treadmill protocol. The training load for each continuous (TRIMPc = t · k1 · x { ) and interval exercise session (TRIMPi =) was calculated using the relevant equation. Total TRIMP scores (for all exercise), TRIMPc and TRIMPi scores were summed for the peak phase of training. Regression analysis was performed to determine correlation between these scores and percent change in VO2max. RESULTS: VO2max increased from 28.73±4.8 ml/kg/min at baseline to 34.43±5.6 ml/kg/min after training (P< 0.01). Total TRIMP score was 4411±1127 for the peak phase, while TRIMPc score was 2353±699 and TRIMPi score was 2059±638. Total TRIMP score did not correlate with increase in relative VO2max (R2 = 0.04, P=0.31), nor did TRIMPc score (R2=0.00 P=0.92). However, TRIMPi score correlated with increased VO2max (R2=0.14, P=0.05). Moreover, there was a significantly greater percent increase in relative VO2max in individuals whose TRIMPi scores were in the top third of the group compared to those in the bottom third (24.70%±9.10 vs15.11%±7.33, P=0.0188). CONCLUSIONS: Our data suggests that interval TRIMP scores predict changes in relative VO2max in middle-aged, sedentary individuals undergoing exercise training. In conclusion, interval training may provide a greater stimulus for aerobic adaptation than continuous endurance training.

12 Day Adventure Run Training at Altitude Improves Sea Level 5km Performance - A Pilot Study

High-altitude (HA) training for 3-6 weeks has been an integral part of many elite endurance training programs for the past few decades. However, less is known about performance changes after only 12 days and what this might mean for sea level performance. PURPOSE: Therefore, we measured the effect of a 12-day adventure running camp at altitude on 5 km time trial (TT) performance and hypothesized an improvement would occur. METHODS: A group of 5 individuals (22-32 years old; 3 male, 2 female) volunteered. All runners began the study with at least 2-months of consistent training (e.g., 3-4 days and 10-30 mi·wk-1 of running per week). In a standardized fashion, 5km TT run, maximal volume of oxygen uptake (VO2max), running economy (RE), and a complete blood chemistry (CBC) assessment were measured at sea-level prior to and immediately after the running camp. VO2max and RE were tested simultaneously with an incremental treadmill protocol. Blood was drawn by certified phlebotomists in the antecubital vein of individual’s preferred arm in a well hydrated and rested state. Natural altitude exposure (i.e., 7,000 to 14,000 ft ASL) occurred in Colorado where runners engaged in prescribed, low-moderate intensity (e.g., approximately 50-60% heart rate max) and long duration (i.e., 2-7 hrs·day-1) exercise for 12 days. Sleeping was maintained at 7,000 ft ASL. After 12 days, runners traveled to sea-level and post-testing within 2-days of leaving altitude. Paired t-tests were utilized to describe differences between pre- and post-tests with p < 0.05 set for significance. RESULTS: In relation to select CBC parameters, significant changes occurred (p < .05) and are as follows from pre- to post-altitude, respectively: hemoglobin concentration (HC; 13.8 ± 2.2 & 15.04 ± 2.1 g/dl), red blood cell count (RBC; 4.83 ± 0.47 & 5.09 ± 0.43 x 106/ul), and hematocrit (Hct; 41.9 ± 5.6 & 44.8 ± 5.7 %). Mean 5 km TT performance also changed significantly from pre to post, respectively (21.49 ± 2.7 & 20.85 min ± 2.7). There was no significant (p > 0.05) difference observed for VO2max or RE. CONCUSION: Since 5km TT performance improved, our hypothesis was supported. Because no significant change occurred with respect to VO2max and RE, positive blood changes, such as increased HC, RBC, and Hct, may have contributed to improved TT performance.

Energy Expenditure Associated With Froude Number And Traditional Speed Measures In Children And Adolescents.

Energy expenditure or metabolic cost of walking is related to speed of locomotion. Leg length normalized speed measures may improve the ability to predict the metabolic cost of walking across the developmental age range. Metrics that improve the strength of the relationship between subject size, walking speed and its metabolic cost may enhance the ability to provide universal recommendations of walking behavior that may serve to improve health. PURPOSE: The purpose of this study was to compare the predictive value of speed in standard units (STD, m/s) to leg length (LL) normalized speed values: the Froude number (Fr) and Dimensionless Speed (DLS) on the metabolic cost of walking in persons 6-20 years of age. We hypothesize that Fr and DLS will improve the prediction of metabolic cost of bipedal transport in children and adolescents. METHODS: : 120 children and adolescents (50% female, 13.1 ± 4.2 years, height 155.6 ± 16.6 cm, mass 56.3 ± 22.3 kg, LL 74.1 ± 9.0 cm) participated in this study. O2 consumption was measured by a K4 portable metabolic system (COSMED). Individuals completed an incremental treadmill protocol 0.22-2.23 m/s, in 0.22m/s increments. The square root of the metabolic data (ml*kg-1*min-1) were compared with all ambulatory speed measures: STD, Fr and DLS. The Akaike information criterion (AIC) was used to compare the linear and quadratic regression models of each gait measure and square root of metabolic cost of walking, best models were selected based on AIC weights. RESULTS: : AIC values indicated that quadratic model provided a better fit for all models of speed and the metabolic cost of walking. AIC weights indicated that DLS (AIC = -489.59) was 315 and 2.45 * 106 times better than Fr (AIC = -478.08) and STD (AIC = -460.16), predicting the metabolic cost of locomotion. CONCLUSIONS: The DLS method of scaling gait speed to leg length offers significant improvements in the ability to predict metabolic cost of locomotion in children and adolescents ages 6-20. Improving the ability to predict metabolic cost from gait parameters may enhance the ability to provide public health recommendations based on objectively measured gait parameters. Funded by Eunice Kennedy Shriver National Institute of Child Health and Human Development: 1R21HD073807-01A1

Postural Control in Dual-Task Situations: Does Whole-Body Fatigue Matter?

Postural control is important to cope with demands of everyday life. It has been shown that both attentional demand (i.e., cognitive processing) and fatigue affect postural control in young adults. However, their combined effect is still unresolved. Therefore, we investigated the effects of fatigue on single- (ST) and dual-task (DT) postural control. Twenty young subjects (age: 23.7 ± 2.7) performed an all-out incremental treadmill protocol. After each completed stage, one-legged-stance performance on a force platform under ST (i.e., one-legged-stance only) and DT conditions (i.e., one-legged-stance while subtracting serial 3s) was registered. On a second test day, subjects conducted the same balance tasks for the control condition (i.e., non-fatigued). Results showed that heart rate, lactate, and ventilation increased following fatigue (all p < 0.001; d = 4.2–21). Postural sway and sway velocity increased during DT compared to ST (all p < 0.001; d = 1.9–2.0) and fatigued compared to non-fatigued condition (all p < 0.001; d = 3.3–4.2). In addition, postural control deteriorated with each completed stage during the treadmill protocol (all p < 0.01; d = 1.9–3.3). The addition of an attention-demanding interference task did not further impede one-legged-stance performance. Although both additional attentional demand and physical fatigue affected postural control in healthy young adults, there was no evidence for an overadditive effect (i.e., fatigue-related performance decrements in postural control were similar under ST and DT conditions). Thus, attentional resources were sufficient to cope with the DT situations in the fatigue condition of this experiment.