Todd Astorino

Recommendations for Improved Data Processing from Expired Gas Analysis Indirect Calorimetry

There is currently no universally recommended and accepted method of data processing within the science of indirect calorimetry for either mixing chamber or breath-by-breath systems of expired gas analysis. Exercise physiologists were first surveyed to determine methods used to process oxygen consumption (V̇O2) data, and current attitudes to data processing within the science of indirect calorimetry. Breath-by-breath datasets obtained from indirect calorimetry during incremental exercise were then used to demonstrate the consequences of commonly used time, breath and digital filter post-acquisition data processing strategies. Assessment of the variability in breath-by-breath data was determined using multiple regression based on the independent variables ventilation (VE), and the expired gas fractions for oxygen and carbon dioxide, FEO2 and FECO2, respectively. Based on the results of explanation of variance of the breath-by-breath V̇O2 data, methods of processing to remove variability were proposed for time-averaged, breath averaged and digital filter applications. Among exercise physiologists, the strategy used to remove the variability in sequential V̇O2 measurements varied widely, and consisted of time averages (30 sec [38%], 60 sec [18%], 20 sec [11%], 15 sec [8%]), a moving average of five to 11 breaths (10%), and the middle five of seven breaths (7%). Most respondents indicated that they used multiple criteria to establish maximum V̇O2 (V̇O2max) including: the attainment of age-predicted maximum heart rate (HRmax) [53%], respiratory exchange ratio (RER) >1.10 (49%) or RER >1.15 (27%) and a rating of perceived exertion (RPE) of >17, 18 or 19 (20%). The reasons stated for these strategies included their own beliefs (32%), what they were taught (26%), what they read in research articles (22%), tradition (13%) and the influence of their colleagues (7%). The combination of VE, FEO2 and FECO2 removed 96–98% of V̇O2 breath-by-breath variability in incremental and steady-state exercise V̇O2 data sets, respectively. Correction of residual error in V̇O2 datasets to 10% of the raw variability results from application of a 30-second time average, 15-breath running average, or a 0.04 Hz low cut-off digital filter. Thus, we recommend that once these data processing strategies are used, the peak or maximal value becomes the highest processed datapoint. Exercise physiologists need to agree on, and continually refine through empirical research, a consistent process for analysing data from indirect calorimetry.

Effect of High-Intensity Interval Training on Cardiovascular Function, Oo2max, and Muscular Force

Astorino, TA, Allen, RP, Roberson, DW, and Jurancich, M. Effect of high-intensity interval training on cardiovascular function, &OV0312;o2max, and muscular force. J Strength Cond Res 26(1): 138–145, 2012—The purpose of this study was to examine the effects of short-term high-intensity interval training (HIIT) on cardiovascular function, cardiorespiratory fitness, and muscular force. Active, young (age and body fat = 25.3 ± 4.5 years and 14.3 ± 6.4%) men and women (N = 20) of a similar age, physical activity, and maximal oxygen uptake (&OV0312;o2max) completed 6 sessions of HIIT consisting of repeated Wingate tests over a 2- to 3-week period. Subjects completed 4 Wingate tests on days 1 and 2, 5 on days 3 and 4, and 6 on days 5 and 6. A control group of 9 men and women (age and body fat = 22.8 ± 2.8 years and 15.2 ± 6.9%) completed all testing but did not perform HIIT. Changes in resting blood pressure (BP) and heart rate (HR), &OV0312;o2max, body composition, oxygen (O2) pulse, peak, mean, and minimum power output, fatigue index, and voluntary force production of the knee flexors and extensors were examined pretraining and posttraining. Results showed significant (p < 0.05) improvements in &OV0312;o2max, O2 pulse, and Wingate-derived power output with HIIT. The magnitude of improvement in &OV0312;o2max was related to baseline &OV0312;o2max (r = −0.44, p = 0.05) and fatigue index (r = 0.50, p < 0.05). No change (p > 0.05) in resting BP, HR, or force production was revealed. Data show that HIIT significantly enhanced &OV0312;o2max and O2 pulse and power output in active men and women.

Alterations in VO2max and the VO2 plateau with manipulation of sampling interval

Background:  The most accepted criterion for confirming attainment of VO2max is a plateau in oxygen consumption (VO2) at VO2max, but its incidence varies.

Minimal Effect of Acute Caffeine Ingestion on Intense Resistance Training Performance

Astorino, TA, Martin, BJ, Schachtsiek, L, Wong, K, and Ng, K. Minimal effect of acute caffeine ingestion on intense resistance training performance. J Strength Cond Res 25(6): 1752-1758, 2011—The primary aim of the study was to determine the efficacy of acute caffeine intake to enhance intense resistance training performance. Fourteen resistance-trained men (age and body mass = 23.1 ± 1.1 years and 83.4 ± 13.2 kg, respectively) who regularly consumed caffeine ingested caffeine (6 mg·kg−1) or placebo 1 hour before completion of 4 sets of barbell bench press, leg press, bilateral row, and barbell shoulder press to fatigue at 70-80% 1-repetition maximum. Two minutes of rest was allotted between sets. Saliva samples were obtained to assess caffeine concentration. The number of repetitions completed per set and total weight lifted were recorded as indices of performance. Two-way analysis of variance with repeated measures was used to examine differences in performance across treatment and sets. Compared to placebo, there was a small but significant effect (p < 0.05) of acute caffeine intake on repetitions completed for the leg press but not for upper-body exercise (p > 0.05). Total weight lifted across sets was similar (p > 0.05) with caffeine (22,409.5 ± 3,773.2 kg) vs. placebo (21,185.7 ± 4,655.4 kg), yet there were 9 ‘responders’ to caffeine, represented by a meaningful increase in total weight lifted with caffeine vs. placebo. Any ergogenic effect of caffeine on performance of fatiguing, total-body resistance training appears to be of limited practical significance. Additional research is merited to elucidate interindividual differences in caffeine-mediated improvements in performance.

Effect of caffeine on RPE and perceptions of pain, arousal, and pleasure/displeasure during a cycling time trial in endurance trained and active men.

Caffeine has been reported to alter perceptions of exertion, muscle pain, and mood, yet the majority of existing data were obtained in resting volunteers or during steady-state exercise. The primary aim of this study was to examine the effects of caffeine on rating of perceived exertion (RPE) and perceptions of leg pain, arousal, and pleasure/displeasure during a simulated cycling time trial. Endurance-trained (n=8, VO(2)max=57.5±3.9 mL/kg/min) and active (n=8, VO(2)max=46.5±6.3 mL/kg/min) men initially completed two familiarization trials separated by at least 48 h. Over the next three trials, they completed a 10 km time trial preceded by ingestion of drinks containing caffeine (5 mg/kg ingested on 2 separate days) or placebo. Treatments were ingested using a single-blind, crossover design, and participants were deceived as to the content of all drinks. During exercise, RPE (6-20 scale), leg pain (0-10 scale), arousal (Felt Arousal Scale), and pleasure/displeasure (Feeling Scale) were recorded using various categorical scales. Repeated measures analysis of variance was used to assess differences in all variables across time and treatments, with fitness level used as a between-subjects variable. Pleasure/displeasure was altered (p<0.05, partial eta-squared (η(2))=0.23) with caffeine compared to placebo, although leg pain, RPE, and arousal were similar (p>0.05) across treatments. Caffeine increased (p<0.05, η(2)=0.27) cycling performance by 0.3-2.0% versus placebo, with no effect (p>0.05) of fitness level. Only in trained men; however, was there a significant caffeine-mediated improvement in cycling performance, which was consequent with diminished mood in trained and improved mood in active individuals.

Changes in physical fitness parameters during a competitive field hockey season.

Competitive field hockey requires a substantial amount of muscular strength, speed, and cardiovascular endurance. It is unknown how these parameters of physical fitness change between preseason conditioning to postseason recovery. Therefore, Division III female field hockey athletes (n = 13) completed tests of muscular strength, body composition, and maximal oxygen uptake (VO2max) during each phase of their season. Muscular strength was assessed using 1 repetition maximum (RM) leg and bench press tests. Body composition was assessed by anthropometry (skinfolds [SKF]), circumferences ([CC]), and bioelectrical impedance analysis (BIA). Incremental treadmill testing was administered to assess VO2max. VO2max was unchanged during the season, although a trend (p > 0.05) was shown for a higher VO2max during and after the season vs. before the season. Upper- (10%) and lower-body strength (14%) decreased (p > 0.05) during the season. Percent body fat (%BF) from BIA, fat mass (FM) from CC, and body mass index (BMI) were significantly lower (p < 0.05) in-season and postseason vs. preseason. In conclusion, preseason training was effective in decreasing %BF and increasing VO2max, yet muscular strength was lost. Coaches should incorporate more rigorous in-season resistance training to prevent strength decrements. Moreover, these data support the superior levels of muscular strength and leanness in these athletes compared with age-matched peers.

Effect of two doses of caffeine on muscular function during isokinetic exercise.

UNLABELLED Studies provide equivocal results regarding the ergogenic properties of caffeine during high-intensity exercise. PURPOSE The primary aim of this study was to examine the effects of two doses of caffeine on peak/average torque, power output, and total work of the knee extensors and flexors during two bouts of high-intensity exercise. METHODS Fifteen active men (mean age = 26.4 ± 3.9 yr and body mass = 82.7 ± 2.9 kg) initially completed a familiarization bout on the isokinetic dynamometer, followed by three subsequent trials separated by at least 48 h. Exercise consisted of two bouts of 40 repetitions of maximal knee extension and flexion of the dominant leg at a contraction velocity equal to 180°·s. Before each trial, subjects abstained from caffeine intake and intense exercise for 48 h. Treatment order (5 and 2 mg·kg of anhydrous caffeine or placebo) was randomly assigned to subjects using a single-blind, randomized, counterbalanced, crossover design. A 3 (treatment) × 2 (sets) ANOVA with repeated measures was used to detect differences in performance across treatment and time. RESULTS Compared with placebo, caffeine significantly (P < 0.05) enhanced peak knee flexion torque, knee extension/flexion total work, and knee extension/flexion power in bout 1 with no effect in bout 2. Only the 5-mg·kg dose of caffeine improved performance, with the magnitude of performance improvement ranging from 5% to 8%. CONCLUSIONS Data suggest that a relatively high (5-mg·kg body weight) but not low (2-mg·kg body weight) caffeine dose is ergogenic for maximal knee extension/flexion exercise.

Effect of two doses of interval training on maximal fat oxidation in sedentary women.

INTRODUCTION The primary aim of the current study was to determine the effect of two doses of chronic high-intensity interval training (HIT) on changes in maximal fat oxidation (MFO) and body composition. METHODS Sedentary women (N = 23, age and V˙O2max = 24.2 ± 6.2 yr and 30.3 ± 5.2 mL·kg-1·min-1, respectively) completed either high (HI) (80%-90% maximal workload) or moderate (MOD) intensity (60%-80% maximal workload) HIT on a cycle ergometer 3 d·wk-1 for 12 wk consisting of 6-10 sixty-second bouts interspersed with active recovery. Seven women of similar age and fitness level served as controls. Every 3 wk, substrate oxidation was assessed during progressive exercise via indirect calorimetry to determine MFO and minimum fat oxidation, and body composition was assessed every 6 wk. Repeated-measures ANOVA was used to examine changes in substrate oxidation in response to training, with training group used as a between-subjects variable. RESULTS Results revealed improved MFO (P = 0.04, 19%-25%) and minimum fat oxidation (P = 0.001, 22-24 W) in response to HIT, yet the magnitude of improvement was similar (P > 0.05) between training paradigms. No change (P > 0.05) in body weight, percent body fat, or waist-hip circumference was revealed with training. CONCLUSION These data suggest that 12 wk of either moderate or more strenuous interval training similarly enhance fat oxidation in sedentary women but do not alter body weight or body composition.

Supramaximal testing to confirm attainment of VO2max in sedentary men and women.

Supramaximal testing is widely used to verify VO2max attainment, yet its efficacy in sedentary subjects is unknown. The aim of the study was to test this hypothesis in men and women completing maximal cycle ergometry. Fifteen sedentary subjects (age=22.4+/-3.9 year) completed incremental exercise, and returned at least 24 h later to complete constant load exercise at 105% peak work rate (Wmax). Another group of nine sedentary men and women (age=21.8+/-5 year) completed supramaximal exercise at 115% Wmax 1-1.5 h after incremental exercise. During exercise, gas exchange data and heart rate (HR) were continuously obtained. VO2max was similar (p>0.05) between incremental and supramaximal exercise in subjects in the first (32.32+/-4.81 mL/kg/min vs. 31.80+/-5.35 mL/kg/min) and second subset (40.63+/-3.61 mL/kg/min vs. 41.66+/-5.55 mL/kg/min). Maximal HR was lower (p<0.05) with supramaximal exercise, yet respiratory exchange ratio was higher (p<0.05). Test-retest reliability (r=0.81-0.89, p<0.05) for VO2max was high during repeated bouts of supramaximal testing. Findings support use of this protocol to confirm VO2max attainment in healthy, sedentary men and women completing incremental cycle ergometry.

Assessment of anaerobic power to verify VO2max attainment

Across various populations, verification testing is used to confirm VO2max attainment and has repeatedly shown similar VO2max values to those obtained from incremental exercise. Yet, many individuals show meaningful differences in VO2max between protocols, and an explanation for this is unknown. The aim of the study was to elucidate this phenomenon in 30 men and women of similar age, fitness, and physical activity using assessment of anaerobic power. On day 1, they completed the Wingate test, and returned at least 48 h later to complete incremental cycle ergometry followed by a verification protocol. During exercise, ventilation, pulmonary gas exchange data, and heart rate (HR) were continuously measured. Mean VO2max was similar (P > 0·05) between protocols (42·05 ± 5·88 ml kg−1 per min versus 42·03 ± 5·75 ml kg−1 per min, respectively), although seven subjects (23%) revealed a VO2max that was not ‘verified’ by the supramaximal protocol. Indices of power output and gas exchange data were similar (P > 0·05) between subjects who revealed a ‘true’ VO2max compared to those who did not, although peak and mean power was consistently higher in persons whose VO2max was not ‘verified.’ A previously established HRmax criterion for verification testing was not met in 17% of subjects. Additional study is merited to identify alternate determinants of VO2max, such as muscle activation via assessment of motor unit recruitment, and to investigate utility of verification testing to confirm VO2max attainment in elite athletes and the elderly.