Verification Testing to Confirm VO2max in Altitude-Residing, Endurance-Trained Runners

Supramaximal Testing to Confirm the Achievement of V̇O 2max in Acute Hypoxia

PURPOSE

We sought to determine if supramaximal exercise testing confirms the achievement of V̇O 2max in acute hypoxia. We hypothesized that the incremental and supramaximal V̇O 2 will be sufficiently similar in acute hypoxia.

METHODS

Twenty-one healthy adults (males n = 13, females n = 8) completed incremental and supramaximal exercise tests in normoxia and acute hypoxia (fraction inspired oxygen = 0.14) separated by at least 48 h. Incremental exercise started at 80 and 60 W in normoxia and 40 and 20 W in hypoxia for males and females, respectively, with all increasing by 20 W each minute until volitional exhaustion. After a 20-min postexercise rest period, a supramaximal test at 110% peak power until volitional exhaustion was completed.

RESULTS

Supramaximal exercise testing yielded a lower V̇O 2 than incremental testing in hypoxia (3.11 ± 0.78 vs 3.21 ± 0.83 L·min -1 , P = 0.001) and normoxia (3.71 ± 0.91 vs 3.80 ± 1.02 L·min -1 , P = 0.01). Incremental and supramaximal V̇O 2 were statistically similar, using investigator-determined equivalence bounds ±150 mL·min -1 , in hypoxia ( P = 0.02, 90% confidence interval [CI] = 0.05-0.14) and normoxia ( P = 0.03, 90% CI = 0.01-0.14). Likewise, using ±2.1 mL·kg -1 ·min -1 bounds, incremental and supramaximal V̇O 2 values were statistically similar in hypoxia ( P = 0.04, 90% CI = 0.70-2.0) and normoxia ( P = 0.04, 90% CI = 0.30-2.0).

CONCLUSIONS

Despite differences in the oxygen cascade, incremental and supramaximal V̇O 2 values were statistically similar in both hypoxia and normoxia, demonstrating the utility of supramaximal verification of V̇O 2max in the setting of acute hypoxia.

A Preliminary Investigation into the Frequency Dose Effects of High-Intensity Functional Training on Cardiometabolic Health

The objective of this study was to explore the effects of three weekly frequency doses of high-intensity functional training (HIFT) on an array of cardiometabolic markers in adults with metabolic syndrome (MetS). Twenty-one men and women, randomized into one (HIFT1), two (HIFT2), or three (HIFT3) days per week of HIFT, completed 3-weeks of familiarization plus a 12-week progressive training program. Pre- and post-intervention, several cardiometabolic, body composition, oxygen consumption, metabolic syndrome severity, and perceptions of fitness measurements were assessed. Additionally, an exercise enjoyment survey was administered post-intervention. A Cohen's d was used to demonstrate within-group change effect size. Although this study was not fully powered, a one-way and two-way ANOVA were used to compare the dose groups to provide provisional insights. No differences were found when frequency dose groups were compared. Many cardiometabolic, body composition, and fitness improvements were seen within each group, with clinically meaningful improvements in the metabolic syndrome severity score (MSSS) (HIFT1: -0.105, d = 0.28; HIFT2: -0.382, d = 1.20; HIFT3: -0.467, d = 1.07), waist circumference (HIFT1: -4.1cm, d = 3.33; HIFT2: -5.4cm, d = 0.89; HIFT3: -0.7cm, d = 0.20), and blood glucose (HIFT1: -9.5mg/dL, d = 0.98; HIFT2: -4.9mg/dL, d = 1.00; HIFT3: -1.7mg/dL, d = 0.23). All three groups similarly reported high exercise enjoyment and likeliness to continue after the intervention. In conclusion, HIFT performed once, twice, or thrice a week elicits improvements in MetS and is considered enjoyable. HIFT, even at a low weekly dose, therefore represents a potential strategy to reduce the global MetS burden.

Verification Phase Confirms V̇O 2max in a Hot Environment in Sedentary Untrained Males

PURPOSE

This study aimed to assess the V̇O 2 uptake obtained during a GXT and subsequent verification phase in untrained participants in a hot environment.

METHODS

Twelve sedentary males completed a GXT followed by a biphasic supramaximal-load verification phase in a hot environment (39°C, 32% relative humidity). Rest between tests occurred in a temperate chamber and lasted until gastrointestinal temperature returned to baseline.

RESULTS

Mean verification phase V̇O 2max (37.8 ± 4.3 mL·kg -1 ·min -1 ) was lower than GXT (39.8 ± 4.1 mL·kg -1 ·min -1 ; P = 0.03) and not statistically equivalent. Using an individualized analysis approach, only 17% (2/12) of participants achieved a V̇O 2 plateau during the GXT. Verification phase confirmed GXT V̇O 2max in 100% of participants, whereas the traditional and the new age-dependent secondary V̇O 2max criteria indicated GXT V̇O 2max achievement at much lower rates (8/12 [67%] vs 7/12 [58%], respectively). Correlational indices between GXT and verification phase V̇O 2max were strong (intraclass correlation coefficient = 0.95, r = 0.86), and Bland-Altman analysis revealed a low mean bias of -2.1 ± 1.9 mL·kg -1 ·min -1 and 95% limits of agreement (-5.8 to 1.7 mL·kg -1 ·min -1 ).

CONCLUSIONS

Very few untrained males achieved a V̇O 2 plateau during GXT in the heat. When conducting GXT in a hot condition, the verification phase remains a valuable addition to confirm V̇O 2max in untrained males.

The Effects of a Single Session of High Intensity Functional Training on Energy Expenditure, VO2, and Blood Lactate

High intensity functional training (HIFT) provides a potential option to meet public exercise recommendations for both cardiorespiratory and strength outcomes in a time efficient manner. To better understand the potential for HIFT as an exercise approach, energy expenditure (EE) and relative intensity need quantifying. In thirteen sedentary men and women with metabolic syndrome (MetS), we used both indirect calorimetry and blood lactate levels to calculate EE of a single session of HIFT. The HIFT session included four, 6-minute sets of consecutive functional exercises. Examples of the exercises involved were squats, deadlifts, suspension rows, suspension chest press, and planks. Intensity is described relative to individual ventilatory thresholds. The total group EE was 270.3 ± 77.3 kcal with approximately 5% attributed anaerobic energy production. VO2 ranged between 88.8 ± 12.3% and 99 ± 12% of the second ventilatory threshold (VT2), indicating a vigorous effort. After each work interval, peak blood lactate ranged between 7.9 ± 1.9 and 9.3 ± 2.9 mmol, and rate of perceived exertion between 6.9 ± 1.0 and 8.7 ± 0.8 arbitrary units from 1-10. These were achieved in approximately 46 minutes of exercise per participant. In conclusion, HIFT elicits the energy expenditure and effort requisite to result in the adaptive responses to produce the known suite of benefits of exercise for individuals with MetS.

Effect of Cardiorespiratory Fitness on Verifying VO2max in Middle-aged and Older Adults

We investigated the effect of cardiorespiratory fitness (CRF) on the probability of achieving the verification criterion to confirm that VO₂max was obtained in a sample of middle-aged to older adults. Data from twelve men and nine women (60.7±8.5 years, VO₂max: 34.8±9.4 mL/kg/min) were used for analysis. Participants had their VO₂max measured via a maximal graded exercise test and confirmed using a verification bout on a cycle ergometer. Logistic regression was used to evaluate the effect of CRF (VO₂max) on the probability a participant would successfully achieve the verification criterion. Odds ratios are reported to quantify the effect size. No statistically significant relationship was observed between CRF and achieving the verification criterion (β=.081, SE=.0619, Wald=1.420, p=.156). Estimated odds ratio for the effect of CRF on the verification criterion indicated an increase of 8% [Exp(β)=1.08, 95% CI (0.96, 1.22)] in the probability of achieving the verification criterion given a one unit increase in VO₂max. Each 1 mL/kg/min increase in VO₂max results in an 8% increase in the chance that an individual achieves the verification criterion confirming that VO₂max was obtained. Therefore, CRF is likely of practical significance and should be considered when deciding to use a verification trial.

Verification of Maximal Oxygen Uptake in Active Military Personnel During Treadmill Running

ABSTRACT

Figueiredo, PS, Looney, DP, Pryor, JL, Doughty, EM, McClung, HL, Vangala, SV, Santee, WR, Beidleman, BA, and Potter, AW. Verification of maximal oxygen uptake in active military personnel during treadmill running. J Strength Cond Res 36(4): 1053-1058, 2022-It is unclear whether verification tests are required to confirm "true" maximal oxygen uptake (V̇o2max) in modern warfighter populations. Our study investigated the prevalence of V̇o2max attainment in U.S. Army soldiers performing a traditional incremental running test. In addition, we examined the utility of supramaximal verification testing as well as repeated trials for familiarization for accurate V̇o2max assessment. Sixteen U.S. Army soldiers (1 woman, 15 men; age, 21 ± 2 years; height, 1.73 ± 0.06 m; body mass, 71.6 ± 10.1 kg) completed 2 laboratory visits, each with an incremental running test (modified Astrand protocol) and a verification test (110% maximal incremental test speed) on a motorized treadmill. We evaluated V̇o2max attainment during incremental testing by testing for the definitive V̇O2 plateau using a linear least-squares regression approach. Peak oxygen uptake (V̇o2peak) was considered statistically equivalent between tests if the 90% confidence interval around the mean difference was within ±2.1 ml·kg-1·min-1. Oxygen uptake plateaus were identified in 14 of 16 volunteers for visit 1 (87.5%) and all 16 volunteers for visit 2 (100%). Peak oxygen uptake was not statistically equivalent, apparent from the mean difference in V̇o2peak measures between the incremental test and verification test on visit 1 (2.3 ml·kg-1·min-1, [1.3-3.2]) or visit 2 (1.1 ml·kg-1·min-1 [0.2-2.1]). Interestingly, V̇o2peak was equivalent, apparent from the mean difference in V̇o2peak measures between visits for the incremental tests (0.0 ml·kg-1·min-1 [-0.8 to 0.9]) but not the verification tests (-1.2 ml·kg-1·min-1 [-2.2 to -0.2]). Modern U.S. Army soldiers can attain V̇o2max by performing a modified Astrand treadmill running test. Additional familiarization and verification tests for confirming V̇o2max in healthy active military personnel may be unnecessary.

Changes in the Second Ventilatory Threshold Following Individualised versus Standardised Exercise Prescription among Physically Inactive Adults: A Randomised Trial

The second ventilatory threshold (VT2) is established as an important indicator of exercise intensity tolerance. A higher VT2 allows for greater duration of higher intensity exercise participation and subsequently greater reductions in cardiovascular disease (CVD) risk. This study aimed to compare the efficacy of standardised and individualised exercise prescription on VT2 among physically inactive adults. Forty-nine physically inactive male and female participants (48.6 ± 11.5 years) were recruited and randomised into a 12-week standardised (n = 25) or individualised (n = 24) exercise prescription intervention. The exercise intensity for the standardised and individualised groups was prescribed as a percentage of heart rate reserve (HRR) or relative to the first ventilatory threshold (VT1) and VT2, respectively. Participants were required to complete a maximal graded exercise test at pre-and post-intervention to determine VT1 and VT2. Participants were categorised as responders to the intervention if an absolute VT2 change of at least 1.9% was attained. Thirty-eight participants were included in the analysis. A significant difference in VT2 change was found between individualised (pre vs. post: 70.6% vs. 78.7% maximum oxygen uptake (VO2max)) and standardised (pre vs. post: 72.5% vs. 72.3% VO2max) exercise groups. Individualised exercise prescription was significantly more efficacious (p = 0.04) in eliciting a positive response in VT2 (15/19, 79%) when compared to the standardised exercise group (9/19, 47%). Individualised exercise prescription appears to be more efficacious than standardised exercise prescription in eliciting a positive VT2 change among physically inactive adults. Increasing VT2 allows for greater tolerance to higher exercise intensities and therefore greater cardiovascular health outcomes.

The effects of high-intensity functional training on cardiometabolic risk factors and exercise enjoyment in men and women with metabolic syndrome: study protocol for a randomized, 12-week, dose-response trial

Background

Individuals with metabolic syndrome (MetS) are at a greater risk for developing atherosclerotic cardiovascular disease (ASCVD) than those without MetS, due to underlying endothelial dysfunction, dyslipidemia, and insulin resistance. Exercise is an effective primary and secondary prevention strategy for MetS; however, less than 25% of adults meet the minimum stated public recommendations. Barriers often identified are lack of enjoyment and lack of time. High-intensity functional training (HIFT), a time-efficient modality of exercise, has shown some potential to elicit positive affectivity and elicit increased fitness and improved glucose metabolism. However, the effects of HIFT on dyslipidemia and endothelial dysfunction have not been explored nor have the effects been explored in a population with MetS. Additionally, no studies have investigated the minimal dose of HIFT per week to see clinically meaningful changes in cardiometabolic health. The purpose of this study is to (1) determine the dose-response effect of HIFT on blood lipids, insulin resistance, and endothelial function and (2) determine the dose-response effect of HIFT on body composition, fitness, and perceived enjoyment and intention to continue the exercise.

Methods/design

In this randomized, dose-response trial, participants will undergo a 12-week HIFT intervention of either 1 day/week, 2 days/week, or 3 days/week of supervised, progressive exercise. Outcomes assessed at baseline and post-intervention will be multiple cardiometabolic markers, and fitness. Additionally, the participant’s affective response will be measured after the intervention.

Discussion

The findings of this research will provide evidence on the minimal dose of HIFT per week to see clinically meaningful improvements in the risk factors of MetS, as well as whether this modality is likely to mitigate the barriers to exercise. If an effective dose of HIFT per week is determined and if this modality is perceived positively, it may provide exercise specialists and health care providers a tool to prevent and treat MetS.

Trial registration

ClinicalTrials.gov NCT05001126. August 11, 2021.

Comparison of constant load exercise intensity for verification of maximal oxygen uptake following a graded exercise test in older adults

Maximal oxygen uptake (VO2 max) declines with advancing age and is a predictor of morbidity and mortality risk. The purpose here was to assess the utility of constant load tests performed either above or below peak work rate obtained from a graded exercise test for verification of VO2 max in older adults. Twenty-two healthy older adults (9M, 13F, 67 ± 6 years, BMI: 26.3 ± 5.1 kg·m-2 ) participated in the study. Participants were asked to complete two experimental trials in a randomized, counterbalanced cross-over design. Both trials (cycle ergometer) consisted of (1) an identical graded exercise test (ramp) and (2) a constant load test at either 85% (CL85; n = 22) or 110% (CL110; n = 20) of the peak work rate achieved during the associated ramp (performed 10-min post ramp). No significant differences were observed for peak VO2 (L·min-1 ) between CL85 (1.86 ± 0.72; p = 0.679) or CL110 (1.79 ± 0.73; p = 0.200) and the associated ramp (Ramp85, 1.85 ± 0.73; Ramp110, 1.85 ± 0.57). Using the study participant's mean coefficient of variation in peak VO2 between the two identical ramp tests (2.9%) to compare individual differences between constant load tests and the associated ramp revealed 19/22 (86%) of participants achieved a peak VO2 during CL85 that was similar or higher versus the ramp, while only 13/20 (65%) of participants achieved a peak VO2 during CL110 that was similar or higher versus the ramp. These data indicate that if a verification of VO2 max is warranted when testing older adults, a constant load effort at 85% of ramp peak power may be more likely to verify VO2 max as compared to an effort at 110% of ramp peak power.

Verification Testing to Confirm V˙O2max in a Hot Environment

PURPOSE

This study aimed to evaluate the validity and reliability of a verification test to confirm GXT V˙O2max in a hot environment.

METHODS

Twelve recreationally trained cyclists completed a two-test protocol that included a GXT progressing 20 W·min-1 followed by a biphasic supramaximal-load verification test (1 min at 60% increasing to 110% maximal GXT wattage until failure) in a hot environment (39°C, 32% relative humidity). Rest between tests occurred in a thermoneutral room and was anchored to the duration required for gastrointestinal temperature to return to baseline.

RESULTS

Mean verification test V˙O2max (51.3 ± 8.8 mL·kg-1·min-1) was lower than GXT (55.9 ± 7.6 mL·kg-1·min-1, P = 0.02). Verification tests confirmed GXT V˙O2max in 92% of participants using individual analysis thresholds. Bland-Altman analysis revealed a sizable mean bias (-4.6 ± 4.9 mL·kg-1·min-1) with wide 95% limits of agreement (-14.0 to 5.0 mL·kg-1·min-1) across a range of V˙O2max values. The high coefficient of variation (9.6%) and typical error (±3.48 mL·kg-1·min-1) indicate potential issues of test-retest reliability in the heat.

CONCLUSIONS

Verification testing in a hot condition confirmed GXT V˙O2max in virtually all participants, indicating robust utility. To enhance test-retest reliability in this environment, protocol recommendations for work rate and recovery between tests are provided.

The effect of posture on maximal oxygen uptake in active healthy individuals

PURPOSE

Semi-supine and supine cardiopulmonary exercise testing (CPET) with concurrent cardiac imaging has emerged as a valuable tool for evaluating patients with cardiovascular disease. Yet, it is unclear how posture effects CPET measures. We aimed to discern the effect of posture on maximal oxygen uptake (VO₂max) and its determinants using three clinically relevant cycle ergometers.

METHODS

In random order, 10 healthy, active males (Age 27 ± 7 years; BMI 23 ± 2 kg m²) underwent a ramp CPET and subsequent constant workload verification test performed at 105% peak ramp power to quantify VO₂max on upright, semi-supine and supine cycle ergometers. Doppler echocardiography was conducted at peak exercise to measure stroke volume (SV) which was multiplied by heart rate (HR) to calculate cardiac output (CO).

RESULTS

Compared to upright (46.8 ± 11.2 ml/kg/min), VO₂max was progressively reduced in semi-supine (43.8 ± 10.6 ml/kg/min) and supine (38.2 ± 9.3 ml/kg/min; upright vs. semi-supine vs. supine; all p ≤ 0.005). Similarly, peak power was highest in upright (325 ± 80 W), followed by semi-supine (298 ± 72 W) and supine (200 ± 51 W; upright vs. semi-supine vs. supine; all p < 0.01). Peak HR decreased progressively from upright to semi-supine to supine (186 ± 11 vs. 176 ± 13 vs. 169 ± 12 bpm; all p < 0.05). Peak SV and CO were lower in supine relative to semi-supine and upright (82 ± 22 vs. 92 ± 26 vs. 91 ± 24 ml and 14 ± 3 vs. 16 ± 4 vs. 17 ± 4 l/min; all p < 0.01), but not different between semi-supine and upright.

CONCLUSION

VO₂max is progressively reduced in reclined postures. Thus, posture should be considered when comparing VO₂max results between different testing modalities.

Is a verification phase useful for confirming maximal oxygen uptake in apparently healthy adults? A systematic review and meta-analysis

BACKGROUND

The 'verification phase' has emerged as a supplementary procedure to traditional maximal oxygen uptake (VO2max) criteria to confirm that the highest possible VO2 has been attained during a cardiopulmonary exercise test (CPET).

OBJECTIVE

To compare the highest VO2 responses observed in different verification phase procedures with their preceding CPET for confirmation that VO2max was likely attained.

METHODS

MEDLINE (accessed through PubMed), Web of Science, SPORTDiscus, and Cochrane (accessed through Wiley) were searched for relevant studies that involved apparently healthy adults, VO2max determination by indirect calorimetry, and a CPET on a cycle ergometer or treadmill that incorporated an appended verification phase. RevMan 5.3 software was used to analyze the pooled effect of the CPET and verification phase on the highest mean VO2. Meta-analysis effect size calculations incorporated random-effects assumptions due to the diversity of experimental protocols employed. I2 was calculated to determine the heterogeneity of VO2 responses, and a funnel plot was used to check the risk of bias, within the mean VO2 responses from the primary studies. Subgroup analyses were used to test the moderator effects of sex, cardiorespiratory fitness, exercise modality, CPET protocol, and verification phase protocol.

RESULTS

Eighty studies were included in the systematic review (total sample of 1,680 participants; 473 women; age 19-68 yr.; VO2max 3.3 ± 1.4 L/min or 46.9 ± 12.1 mL·kg-1·min-1). The highest mean VO2 values attained in the CPET and verification phase were similar in the 54 studies that were meta-analyzed (mean difference = 0.03 [95% CI = -0.01 to 0.06] L/min, P = 0.15). Furthermore, the difference between the CPET and verification phase was not affected by any of the potential moderators such as verification phase intensity (P = 0.11), type of recovery utilized (P = 0.36), VO2max verification criterion adoption (P = 0.29), same or alternate day verification procedure (P = 0.21), verification-phase duration (P = 0.35), or even according to sex, cardiorespiratory fitness level, exercise modality, and CPET protocol (P = 0.18 to P = 0.71). The funnel plot indicated that there was no significant publication bias.

CONCLUSIONS

The verification phase seems a robust procedure to confirm that the highest possible VO2 has been attained during a ramp or continuous step-incremented CPET. However, given the high concordance between the highest mean VO2 achieved in the CPET and verification phase, findings from the current study would question its necessity in all testing circumstances.

PROSPERO REGISTRATION ID

CRD42019123540.

Is a verification phase needed to determine [Formula: see text]O2max across fitness levels?

INTRODUCTION

Current methods (plateau/secondary criteria) to determine maximal oxygen consumption ([Formula: see text]O_2max) are inconsistently achieved leading some to suggest the use of a verification phase (VP) to confirm [Formula: see text]O_2max.

PURPOSE

To provide further evidence for the inclusion of a VP to confirm [Formula: see text]O_2max in different fitness levels.

METHODS

Forty-nine participants (22 females; 21.9 ± 2.6 years, 24.3 ± 2.8 kg m^-2, 45.27 ± 7.68 mL kg^-1 min^-1) had their [Formula: see text]O₂ and heart rate measured during three graded exercise tests (GXT) on separate days each followed by a VP of differing intensity (85%, 95%, 105% final workload). Participants were divided into groups using norms adapted from American College of Sports Medicine [Formula: see text]O_2max guidelines (30.47-61.47 mL kg^-1 min^-1). [Formula: see text]O_2max was confirmed if the [Formula: see text]O_2peak on the VP or an additional GXT was within ± 2 × typical error of the [Formula: see text]O_2peak attained on the first GXT. There was no effect of test number so the third GXT was not included in comparison with VP.

RESULTS

The [Formula: see text]O_2peak from the first GXT was not different than either value attained following the VP at 95 or 105% workload or a second GXT (p > 0.999). The 85% VP [Formula: see text]O_2peak was lower than the first GXT [Formula: see text]O_2peak (p = 0.002). The VP confirmed the GXT [Formula: see text]O_2peak on 73% of VP (no differences among fitness levels). Submaximal VP (85 and 95%) was less effective as 65% and 51% of participants achieved a higher [Formula: see text]O_2peak on one of the GXT.

CONCLUSION

The use of a VP at 105% or a second GXT was able to confirm the [Formula: see text]O_2max value attained across a range of fitness levels.

Predicting Maximal Oxygen Uptake Using the 3-Minute All-Out Test in High-Intensity Functional Training Athletes

Maximal oxygen uptake (VO2max) and critical speed (CS) are key fatigue-related measurements that demonstrate a relationship to one another and are indicative of athletic endurance performance. This is especially true for those that participate in competitive fitness events. However, the accessibility to a metabolic analyzer to accurately measure VO2max is expensive and time intensive, whereas CS may be measured in the field using a 3 min all-out test (3MT). Therefore, the purpose of this study was to examine the relationship between VO2max and CS in high-intensity functional training (HIFT) athletes. Twenty-five male and female (age: 27.6 ± 4.5 years; height: 174.5 ± 18.3 cm; weight: 77.4 ± 14.8 kg; body fat: 15.7 ± 6.5%) HIFT athletes performed a 3MT as well as a graded exercise test with 48 h between measurements. True VO2max was determined using a square-wave supramaximal verification phase and CS was measured as the average speed of the last 30 s of the 3MT. A statistically significant and positive correlation was observed between relative VO2max and CS values (r = 0.819, p < 0.001). Based on the significant correlation, a linear regression analysis was completed, including sex, in order to develop a VO2max prediction equation (VO2max (mL/kg/min) = 8.449(CS) + 4.387(F = 0, M = 1) + 14.683; standard error of the estimate = 3.34 mL/kg/min). Observed (47.71 ± 6.54 mL/kg/min) and predicted (47.71 ± 5.7 mL/kg/min) VO2max values were compared using a dependent t-test and no significant difference was displayed between the observed and predicted values (p = 1.000). The typical error, coefficient of variation, and intraclass correlation coefficient were 2.26 mL/kg/min, 4.90%, and 0.864, respectively. The positive and significant relationship between VO2max and CS suggests that the 3MT may be a practical alternative to predicting maximal oxygen uptake when time and access to a metabolic analyzer is limited.

Does heart rate response confirm the attainment of maximal oxygen uptake in adults 45 years and older?

PURPOSE

To test the efficacy of a plateau in heart rate (HR_plat) as an effective indicator for confirming [Formula: see text]max attainment in a middle-aged to older sample.

METHODS

Nine men and eleven women (age 60 ± 8.5 years, [Formula: see text]max 35.9 ± 9.4 ml/kg/min, N = 20) completed a single [Formula: see text]max test on both the treadmill and cycle ergometer.[Formula: see text]max was confirmed using a plateau in [Formula: see text] ([Formula: see text]_plat) of ≤ 150 ml/min, a verification bout, and HR_plat (≤ 4 bpm).

RESULTS

[Formula: see text]_plat occurred in 100% and 95% of participants on the treadmill and cycle ergometer, respectively. Verification criteria ([Formula: see text]max during verification ≤ 2% of [Formula: see text]max during incremental test) were met by 80% of participants on both modalities. HR_plat was achieved by 90% and 70% of participants on the treadmill and cycle ergometer, respectively.

CONCLUSION

These results suggest that a verification bout is reliable for confirming [Formula: see text]max in older adults on both modalities. In our sample of middle-aged and older adults, [Formula: see text]_plat was the most robust method to assess [Formula: see text]max when indirect calorimetry is available. Although more research is warranted, when indirect calorimetry is not available, a HR_plat of ≤ 4 bpm may be a useful alternative to get an accurate representation of maximal effort in middle-aged and older adults.

Priming exercise increases Wingate cycling peak power output

PURPOSE

The aim of the present study was to investigate the effect of priming exercise on Wingate performance and fatigue.

METHODS

Twelve recreationally active young male volunteers participated in the study (age: 25 ± 5 years; weight: 75.0 ± 7.5 kg; height: 177 ± 6 cm; BMI: 24.0 ± 1.7). During a first visit, participants performed a typical V˙O2max test and a supramaximal assessment of V˙O2max on a cycle ergometer, while during the next three visits, the participants performed in a random order a Wingate test (i) with no priming exercise, (ii) after priming exercise followed by a 15-min recovery (Priming15) and (iii) after priming exercise followed by a 30-min recovery (Priming30). Priming exercise lasted 6 min, at work rate corresponding to the gas exchange threshold (GET) plus 70% of the difference between the GET and V˙O2max.

RESULTS

The Priming 30 condition exhibited greater peak power output (595 ± 84 W) compared to the control (567 ± 85 W) and the Priming15 condition (569 ± 95 W) (P < .05). Regarding fatigue index, a tendency towards increased resistance to fatigue was observed in the Priming30 condition compared to the control and the Priming15 conditions (P = .072). Pre-Wingate lactate levels were found to be significantly different between the Priming15 (7.18 ± 3.09 mmol/L) and the Priming30 (4.87 ± 2.11 mmol/L) conditions (P < .05).

CONCLUSIONS

Priming exercise of high intensity followed by a prolonged recovery leads to increased peak power in a subsequent Wingate test. Moreover, our data are consistent with the idea that a priming exercise-induced modest increase in blood lactate concentration at the onset of the following criterion bout is a key factor of performance.

Incidence of V˙O2max Responders to Personalized versus Standardized Exercise Prescription

INTRODUCTION

Despite knowledge of cardiorespiratory fitness (CRF) training responders and nonresponders, it is not well understood how the exercise intensity prescription affects the incidence of response. The purpose of this study was to determine CRF training responsiveness based on cohort-specific technical error after 12 wk of standardized or individually prescribed exercise and the use of a verification protocol to confirm maximal oxygen uptake (V˙O2max).

METHODS

Sedentary adult participants (9 men, 30 women; 48.2 ± 12.2 yr) completed exercise training on 3 d·wk for 12 wk, with exercise intensity prescribed based on standardized methods using heart rate reserve or an individualized approach using ventilatory thresholds. A verification protocol was used at baseline and 12 wk to confirm the identification of a true V˙O2max and subsequent relative percent changes to quantify CRF training responsiveness. A cohort-specific technical error (4.7%) was used as a threshold to identify incidence of response.

RESULTS

Relative V˙O2max significantly increased (P < 0.05) from 24.3 ± 4.6 to 26.0 ± 4.2 and 29.2 ± 7.5 to 32.8 ± 8.6 mL·kg·min for the standardized and individualized groups, respectively. Absolute V˙O2max significantly increased (P < 0.05) from 2.0 ± 0.6 to 2.2 ± 0.6 and 2.4 ± 0.8 to 2.6 ± 0.9 L·min for the standardized and individualized groups, respectively. A significant difference in responsiveness was found between the individualized and standardized groups with 100% and 60% of participants categorized as responders, respectively.

CONCLUSIONS

A threshold model for exercise intensity prescription had a greater effect on the incidence of CRF training response compared with a standardized approach using heart rate reserve. The use of thresholds for intensity markers accounts for individual metabolic characteristics and should be considered as a viable and practical method to prescribe exercise intensity.

Time Course Changes in Confirmed 'True' VO 2 max After Individualized and Standardized Training

This study sought to examine time course changes in maximal oxygen consumption (VO ₂ max) confirmed with verification testing following 12 weeks of standardized vs. individualized exercise training. Participants (N=39) were randomly allocated to differing exercise intensity prescription groups: ventilatory threshold (individualized) or % heart rate reserve (standardized). At baseline, 4, 8, and 12 weeks, participants completed maximal exercise testing with a verification protocol to confirm ‘true VO ₂ max.’ VO ₂ max in the standardized group changed from 24.3±4.6 ml·kg ⁻¹ ·min ⁻¹ at baseline to 24.7±4.6, 25.9±4.7, and 26.0±4.2 ml·kg ⁻¹ ·min ⁻¹ at week 4, 8, and 12, respectively, with a significant difference (p<0.05) in VO ₂ max at week 8 and 12 compared to baseline. The individualized group had increases in VO ₂ max from _{online 2} 9.5±7.5 ml·kg ⁻¹ ·min ⁻¹ at baseline to 30.6±8.4, 31.4±8.4, and 32.8±8.6 ml·kg ⁻¹ ·min ⁻¹ at week 4, 8, and 12, respectively. In the individualized group, there were significant differences (p<0.05) in VO ₂ max from baseline to week 8 and 12 and a significant increase in VO ₂ max from week 8 to 1 _{online 2} . Although not statistically significant, our preliminary data demonstrates a more rapid and potent improvement in VO ₂ max when exercise intensity is individualized. This is the first investigation to employ use of the verification procedure to confirm ‘true VO ₂ max’ changes following exercise training using ventilatory thresholds.

Changes in Metabolic Syndrome Severity Following Individualized Versus Standardized Exercise Prescription: A Feasibility Study

This study sought to investigate the efficacy of standardized versus individualized exercise intensity prescription on metabolic syndrome (MetS) severity following a 12-week exercise intervention. A total of 38 experimental participants (47.8 ± 12.2 yr, 170.7 ± 8.0 cm, 82.6 ± 18.7 kg, 26.9 ± 6.7 mL·k⁻¹·min⁻¹) were randomized to one of two exercise interventions (exercise intensity prescribed using heart rate reserve or ventilatory threshold). Following the 12-week intervention, MetS z-score was significantly improved for the standardized (−2.0 ± 3.1 to −2.8 ± 2.8 [p = 0.01]) and individualized (−3.3 ± 2.3 to −3.9 ± 2.2 [p = 0.04]) groups. When separating participants based on prevalence of MetS at baseline and MetS z-score responsiveness, there were six and three participants in the standardized and individualized groups, respectively, with three or more MetS risk factors. Of the six participants in the standardized group, 83% (5/6) of the participants were considered responders, whereas 100% (3/3) of the individualized participants were responders. Furthermore, only 17% (1/6) of the participants with MetS at baseline in the standardized group no longer had symptoms of MetS following the intervention. In the individualized group, 67% (2/3) of participants with baseline MetS were not considered to have MetS at week 12. These findings suggest that an individualized approach to the exercise intensity prescription may ameliorate the severity of MetS.

Using a site-specific technical error to establish training responsiveness: a preliminary explorative study

BACKGROUND

Even though cardiorespiratory fitness (CRF) training elicits numerous health benefits, not all individuals have positive training responses following a structured CRF intervention. It has been suggested that the technical error (TE), a combination of biological variability and measurement error, should be used to establish specific training responsiveness criteria to gain further insight on the effectiveness of the training program. To date, most training interventions use an absolute change or a TE from previous findings, which do not take into consideration the training site and equipment used to establish training outcomes or the specific cohort being evaluated. The purpose of this investigation was to retrospectively analyze training responsiveness of two CRF training interventions using two common criteria and a site-specific TE.

METHODS

Sixteen men and women completed two maximal graded exercise tests and verification bouts to identify maximal oxygen consumption (VO2max) and establish a site-specific TE. The TE was then used to retrospectively analyze training responsiveness in comparison to commonly used criteria: percent change of >0% and >+5.6% in VO2max.

RESULTS

The TE was found to be 7.7% for relative VO2 max. χ2 testing showed significant differences in all training criteria for each intervention and pooled data from both interventions, except between %Δ >0 and %Δ >+7.7% in one of the investigations. Training nonresponsiveness ranged from 11.5% to 34.6%.

CONCLUSION

Findings from the present study support the utility of site-specific TE criterion to quantify training responsiveness. A similar methodology of establishing a site-specific and even cohort specific TE should be considered to establish when true cardiorespiratory training adaptations occur.

Measurement of a True [Formula: see text]O2max during a Ramp Incremental Test Is Not Confirmed by a Verification Phase

The accuracy of an exhaustive ramp incremental (RI) test to determine maximal oxygen uptake ([Formula: see text]O_2max) was recently questioned and the utilization of a verification phase proposed as a gold standard. This study compared the oxygen uptake ([Formula: see text]O₂) during a RI test to that obtained during a verification phase aimed to confirm attainment of [Formula: see text]O_2max. Sixty-one healthy males [31 older (O) 65 ± 5 yrs; 30 younger (Y) 25 ± 4 yrs] performed a RI test (15-20 W/min for O and 25 W/min for Y). At the end of the RI test, a 5-min recovery period was followed by a verification phase of constant load cycling to fatigue at either 85% (n = 16) or 105% (n = 45) of the peak power output obtained from the RI test. The highest [Formula: see text]O₂ after the RI test (39.8 ± 11.5 mL·kg^-1·min^-1) and the verification phase (40.1 ± 11.2 mL·kg^-1·min^-1) were not different (p = 0.33) and they were highly correlated (r = 0.99; p < 0.01). This response was not affected by age or intensity of the verification phase. The Bland-Altman analysis revealed a very small absolute bias (-0.25 mL·kg^-1·min^-1, not different from 0) and a precision of ±1.56 mL·kg^-1·min^-1 between measures. This study indicated that a verification phase does not highlight an under-estimation of [Formula: see text]O_2max derived from a RI test, in a large and heterogeneous group of healthy younger and older men naïve to laboratory testing procedures. Moreover, only minor within-individual differences were observed between the maximal [Formula: see text]O₂ elicited during the RI and the verification phase. Thus a verification phase does not add any validation of the determination of a [Formula: see text]O_2max. Therefore, the recommendation that a verification phase should become a gold standard procedure, although initially appealing, is not supported by the experimental data.

Hemodynamic and metabolic responses to self-paced and ramp-graded exercise testing protocols

Recent examinations have shown lower maximal oxygen consumption during traditional ramp (RAMP) compared with self-paced (SPV) graded exercise testing (GXT) attributed to differences in cardiac output. The current study examined the differences in hemodynamic and metabolic responses between RAMP and SPV during treadmill exercise. Sixteen recreationally trained men (aged23.7 ± 3.0 years) completed 2 separate treadmill GXT protocols. SPV consisted of five 2-min stages (10 min total) of increasing speed clamped by the Borg RPE6-20 scale. RAMP increased speed by 0.16 km/h every 15 s until volitional exhaustion. All testing was performed at 3% incline. Oxygen consumption was measured via indirect calorimetry; hemodynamic function was measured via thoracic impedance and blood lactate (BLa^-) was measured via portable lactate analyzer. Differences between SPV and RAMP protocols were analyzed as group means by using paired-samples t tests (R Core Team 2017). Maximal values for SPV and RAMP were similar (p > 0.05) for oxygen uptake (47.1 ± 3.4 vs. 47.4 ± 3.4 mL·kg^-1·min^-1), heart rate (198 ± 5 vs. 200 ± 6 beats·min^-1), ventilation (158.8 ± 20.7 vs. 159.3 ± 19.0 L·min^-1), cardiac output (26.9 ± 5.5 vs. 27.9 ± 4.2 L·min^-1), stroke volume (SV) (145.9 ± 29.2 vs. 149.8 ± 25.3 mL·beat^-1), arteriovenous oxygen difference (18.5 ± 3.1 vs. 19.7 ± 3.1 mL·dL^-1), ventilatory threshold (VT) (78.2 ± 7.2 vs. 79.0% ± 7.6%), and peak BLa^- (11.7 ± 2.3 vs. 11.5 ± 2.4 mmol·L^-1), respectively. In conclusion, SPV elicits similar maximal hemodynamic responses in comparison to RAMP; however, SV kinetics exhibited unique characteristics based on protocol. These results support SPV as a feasible GXT protocol to identify useful fitness parameters (maximal oxygen uptake, oxygen uptake kinetics, and VT).

The Maximal Oxygen Uptake Verification Phase: a Light at the End of the Tunnel?

Commonly performed during an incremental test to exhaustion, maximal oxygen uptake (V̇O_2max) assessment has become a recurring practice in clinical and experimental settings. To validate the test, several criteria were proposed. In this context, the plateau in oxygen uptake (V̇O₂) is inconsistent in its frequency, reducing its usefulness as a robust method to determine “true” V̇O_2max. Moreover, secondary criteria previously suggested, such as expiratory exchange ratios or percentages of maximal heart rate, are highly dependent on protocol design and often are achieved at V̇O₂ percentages well below V̇O_2max. Thus, an alternative method termed verification phase was proposed. Currently, it is clear that the verification phase can be a practical and sensitive method to confirm V̇O_2max; however, procedures to conduct it are not standardized across the literature and no previous research tried to summarize how it has been employed. Therefore, in this review the knowledge on the verification phase was updated, while suggestions on how it can be performed (e.g. intensity, duration, recovery) were provided according to population and protocol design. Future studies should focus to identify a verification protocol feasible for different populations and to compare square-wave and multistage verification phases. Additionally, studies assessing verification phases in different patient populations are still warranted.

Measurement of the maximum oxygen uptake V̇o2max: V̇o2peak is no longer acceptable

The maximum rate of O2 uptake (i.e., V̇o2max), as measured during large muscle mass exercise such as cycling or running, is widely considered to be the gold standard measurement of integrated cardiopulmonary-muscle oxidative function. The development of rapid-response gas analyzers, enabling measurement of breath-by-breath pulmonary gas exchange, has facilitated replacement of the discontinuous progressive maximal exercise test (that produced an unambiguous V̇o2-work rate plateau definitive for V̇o2max) with the rapidly incremented or ramp testing protocol. Although this is more suitable for clinical and experimental investigations and enables measurement of the gas exchange threshold, exercise efficiency, and V̇o2 kinetics, a V̇o2-work rate plateau is not an obligatory outcome. This shortcoming has led to investigators resorting to so-called secondary criteria such as respiratory exchange ratio, maximal heart rate, and/or maximal blood lactate concentration, the acceptable values of which may be selected arbitrarily and result in grossly inaccurate V̇o2max estimation. Whereas this may not be an overriding concern in young, healthy subjects with experience of performing exercise to volitional exhaustion, exercise test naïve subjects, patient populations, and less motivated subjects may stop exercising before their V̇o2max is reached. When V̇o2max is a or the criterion outcome of the investigation, this represents a major experimental design issue. This CORP presents the rationale for incorporation of a second, constant work rate test performed at ~110% of the work rate achieved on the initial ramp test to resolve the classic V̇o2-work rate plateau that is the unambiguous validation of V̇o2max. The broad utility of this procedure has been established for children, adults of varying fitness, obese individuals, and patient populations.

Graded Exercise Testing Protocols for the Determination of VO2max: Historical Perspectives, Progress, and Future Considerations

Graded exercise testing (GXT) is the most widely used assessment to examine the dynamic relationship between exercise and integrated physiological systems. The information from GXT can be applied across the spectrum of sport performance, occupational safety screening, research, and clinical diagnostics. The suitability of GXT to determine a valid maximal oxygen consumption (VO₂max) has been under investigation for decades. Although a set of recommended criteria exists to verify attainment of VO₂max, the methods that originally established these criteria have been scrutinized. Many studies do not apply identical criteria or fail to consider individual variability in physiological responses. As an alternative to using traditional criteria, recent research efforts have been directed toward using a supramaximal verification protocol performed after a GXT to confirm attainment of VO₂max. Furthermore, the emergence of self-paced protocols has provided a simple, yet reliable approach to designing and administering GXT. In order to develop a standardized GXT protocol, additional research should further examine the utility of self-paced protocols used in conjunction with verification protocols to elicit and confirm attainment of VO₂max.

The incidence of training responsiveness to cardiorespiratory fitness and cardiometabolic measurements following individualized and standardized exercise prescription: study protocol for a randomized controlled trial

BACKGROUND

There is individual variability to cardiorespiratory fitness (CRF) training, but the underlying cause is not well understood. Traditionally, a standardized approach to exercise prescription has utilized relative percentages of maximal heart rate, heart rate reserve (HRR), maximal oxygen uptake (VO2max), or VO2 reserve to establish exercise intensity. However, this model fails to take into consideration individual metabolic responses to exercise and may attribute to the variability in training responses. It has been proposed that an individualized approach would take into consideration metabolic responses to exercises to increase responsiveness to training.

METHODS

In this randomized control trial, participants will undergo a 12-week exercise intervention using individualized (ventilatory thresholds) and standardized (HRR) methods to prescribe CRF training intensity. Following the intervention, participants will be categorized as responders or non-responders based on changes in maximal aerobic abilities. Participants who are non-responders will complete a second 12-week intervention in a crossover design to determine whether they can become responders with a differing exercise prescription. There are four main research outcomes: (1) determine the cohort-specific technical error to use in the categorization of response rate; (2) determine if an individualized intensity prescription is superior to a standard approach in regards to VO2max and cardiometabolic risk factors; (3) investigate the time course changes throughout 12 weeks of CRF training between the two intervention groups; and (4) determine if non-responders can become responders if the exercise prescription is modified.

DISCUSSION

The findings from this research will provide evidence on the effectiveness of individualized exercise prescription related to training responsiveness of VO2max and cardiometabolic risk factors compared to a standardized approach and further our understanding of individual exercise responses. If the individualized approach proposed is deemed effective, it may change the way exercise specialists prescribe exercise intensity to enhance training responsiveness.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT02868710 . Registered on 15 August 2016.