Auckland, New Zealand b Department of Human Performance, Minnesota State University,

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1 This article was downloaded by: [Lance Dalleck] On: 29 March 2012, At: 11:02 Publisher: Taylor & Francis Informa Ltd Registered in England and Wales Registered Number: Registered office: Mortimer House, Mortimer Street, London W1T 3JH, UK Research in Sports Medicine: An International Journal Publication details, including instructions for authors and subscription information: Suitability of Verification Testing to Confirm Attainment of VO 2 max in Middle-Aged and Older Adults Lance C. Dalleck a b, Todd A. Astorino c, Rachel M. Erickson d, Caitlin M. McCarthy b, Alyssa A. Beadell b & Brigette H. Botten b a Department of Sport and Exercise Science, University of Auckland, Auckland, New Zealand b Department of Human Performance, Minnesota State University, Mankato, Minnesota, USA c Department of Kinesiology, California State University, San Marcos, California, USA d Department of Kinesiology, University of Wisconsin, Eau Claire, Wisconsin, USA Available online: 29 Mar 2012 To cite this article: Lance C. Dalleck, Todd A. Astorino, Rachel M. Erickson, Caitlin M. McCarthy, Alyssa A. Beadell & Brigette H. Botten (2012): Suitability of Verification Testing to Confirm Attainment of VO 2 max in Middle-Aged and Older Adults, Research in Sports Medicine: An International Journal, 20:2, To link to this article: PLEASE SCROLL DOWN FOR ARTICLE Full terms and conditions of use: This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The accuracy of any instructions, formulae, and drug doses should be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims, proceedings,

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3 Research in Sports Medicine, 20: , 2012 Copyright Taylor & Francis Group, LLC ISSN: print/ online DOI: / Suitability of Verification Testing to Confirm Attainment of VO 2 max in Middle-Aged and Older Adults LANCE C. DALLECK Department of Sport and Exercise Science, University of Auckland, Auckland, New Zealand Department of Human Performance, Minnesota State University, Mankato, Minnesota, USA TODD A. ASTORINO Department of Kinesiology, California State University-San Marcos, San Marcos, California, USA RACHEL M. ERICKSON Department of Kinesiology, University of Wisconsin-Eau Claire, Eau Claire, Wisconsin, USA CAITLIN M. MCCARTHY, ALYSSA A. BEADELL, and BRIGETTE H. BOTTEN Department of Human Performance, Minnesota State University, Mankato, Minnesota, USA The aim of the present study was to test the utility of the verification testing procedure in confirming true VO 2 max in older adults completing maximal cycle ergometry. Eighteen physically active men and women (age = 59.7 ± 6.3 yr, ht = ± 8.8 cm, body mass = 83.2 ± 16.4 kg, VO 2 max = 27.7 ± 5.0 ml/kg/min) completed incremental exercise, and returned 1 h after incremental exercise to complete a verification phase of constant load exercise at 105% peak work rate. During exercise, gas exchange data and heart rate (HR) were continuously monitored. VO 2 max was similar (p > 0.05) between incremental and verification bouts (2329 ± 762 ml/min vs ± 760 ml/min). Findings support use Received 1 May 2010; accepted 30 January Address correspondence to Lance C. Dalleck, Ph.D., Assistant Professor, Department of Human Performance, Minnesota State University, 1400 Highland Center, Mankato, MN 56001, USA. lance.dalleck@mnsu.edu 118

4 Verification Procedure to Confirm VO 2 max 119 of the verification procedure to confirm VO 2 max attainment in active, middle-aged and older adults completing incremental cycle ergometry. This is particularly relevant to interpretation of studies that have used repeated measurements of VO 2 max to establish a training effect or when VO 2 max is used for designing exercise prescriptions. KEYWORDS maximal oxygen uptake, incremental exercise test, true VO 2 max, verification phase, VO 2 plateau, cycle ergometry INTRODUCTION Cardiorespiratory fitness, typically determined by maximal oxygen uptake (VO 2 max), represents the maximal rate of oxygen consumption during exercise testing to volitional fatigue. It is a measure of the circulatory system s maximal ability to use and transport oxygen, and it is commonly measured during graded exercise on a treadmill or cycle ergometer, during which pulmonary gas exchange data are collected. Studies have reported that low cardiorespiratory fitness may contribute to premature mortality in middle-aged and older adults (Blair et al., 1995; Dunn et al., 1999). Further, decreased cardiorespiratory fitness contributes to a reduction in functional capacity and eventually can result in loss of independence (Dempsey & Seals, 1995; Fitzgerald, Tanaka, Tran, & Seals, 1997). Moreover, exercise intensity is commonly prescribed by establishing target workload at a given percentage of maximal oxygen uptake reserve (VO 2 R), which is determined by taking the difference between VO 2 max and resting VO 2 (American College of Sports Medicine [ACSM], 2010). As such, VO 2 max is a fundamental measurement for the clinician and researcher. Although the concept of VO 2 max has existed since the 1920s, no standardized criteria exist to verify its attainment at the end of incremental exercise (Astorino, White, & Dalleck, 2009). In fact, despite considerable criticism, a recent review (Midgley, McNaughton, Polman, & Marchant, 2007) noted that the type and number of criteria, along with the threshold values to define each criterion measure, have remained unchanged over the past decade. Moreover, these same authors report, following a survey of four prominent sport science and applied physiology journals (published from August 2005 to July 2006), that nearly two out of every three studies failed or neglected to report the VO 2 max criteria employed (Midgley et al., 2007). Further, it has been suggested (Astorino et al., 2009) that the most widely used criterion is a plateau in VO 2 at the end of incremental exercise despite an increase in exercise intensity, yet there is no universally accepted definition of the VO 2 plateau. VO 2 plateau incidence widely varies in the literature (17% 100% Astorino, Robergs, Ghiasvand, Marks, & Burns, 2000; Astorino

5 120 L. C. Dalleck et al. et al., 2009; Doherty, Nobbs, & Noakes, 2003; Duncan, Howley, & Johnson, 1997; Lucia et al., 2006; Myers, Walsh, Sullivan, & Froelicher, 1990; Taylor, Buskirk, & Henschel, 1955) due to the multiple criteria used, protocols completed, as well as dissimilar means to analyze and interpret gas exchange data. Consequently, scientists (Day, Rossiter, Coats, Skasick, & Whipp, 2003; Noakes, 1997, 2008a, 2008b, 2008c) have questioned the existence of a true VO 2 max and criticized the VO 2 max concept and the utility of the VO 2 plateau (Howley, 2007) as well. Additionally, secondary criteria frequently employed to confirm VO 2 max, such as a respiratory exchange ratio (RER) >1.10 and attainment of ±10 bpm of age-predicted maximal HR have also been scrutinized. Poole, Wilkerson, and Jones (2008) recently observed that such criteria were often surpassed well prior to attainment of VO 2 max and exercise intolerance; and recommended abandonment of such secondary criteria. Hence, the confirmation of VO 2 max remains a controversial topic that merits additional research. One technique used to verify VO 2 max attainment that does not employ traditional criteria is completion of a constant-load bout at supramaximal workloads, which is typically called a verification protocol. To our knowledge, this was first done by Niemela, Palatsi, Linnaluoto, & Takkunen (1980). In this study, 16 men and women initially completed progressive cycle ergometry followed on a separate day by a supramaximal constant load protocol. Results showed no difference in mean VO 2 max between protocols. Later work from Thoden (1991) in athletes was characterized by completion of repeated verification bouts until the measured VO 2 max was within 2% of the incremental value. Data from recent studies (Astorino et al., 2009; Day et al., 2003; Foster et al., 2007; Hawkins, Raven, Snell, Stray-Gundersen, & Levine, 2007; Midgley, McNaughton, & Carroll, 2006; Poole et al., 2008; Rossiter, Kowalchuk, & Whipp, 2006) in endurance-trained, recreationally active, and sedentary men and women completing a variety of supramaximal work rates corroborate early findings, showing no difference in VO 2 max between the incremental and verification protocol. Consequently, verification testing seems to be a robust procedure, despite various methodological differences across studies, including use of both treadmill exercise and cycle ergometry, dissimilar or absence of criterion values to verify VO 2 max, and various recovery durations (1 10 min) between the incremental and verification bout. Nevertheless, as recently emphasized (Noakes, 2008a), verification of VO 2 max attainment is an individual and not group phenomenon, so mean data often reported in the literature (Foster et al., 2007; Hawkins et al., 2007) do not adequately capture individual responses. Furthermore, it has been suggested that exclusive use of this approach could ignore one or more individuals who have not given a maximal effort and therefore probably not elicited a true VO 2 max. Hence, it has been proposed that verification testing should always be applied on an individual basis. A VO 2 max 2%

6 Verification Procedure to Confirm VO 2 max 121 higher (the day-to-day measurement error of VO 2 max) than the incremental value (Midgley et al., 2006) and peak HR within 4 beats min 1 of each other (Midgley, Carroll, Marchant, McNaughton, & Siegler, 2009) are two criterion measures that might be employed to indicate that a true VO 2 max has been attained. The majority of the data used to describe VO 2 max and the requirements for its attainment have been developed using young adults (Huggett, Connelly, & Overend, 2005), and it is unknown if the verification procedure is efficacious to confirm attainment of VO 2 max in middle-aged and older adults. Therefore, the primary purpose of the present study was to test the utility of the verification procedure for confirming the attainment of VO 2 max in middle-aged and older adults. It was hypothesized that both tests will produce similar determinations for VO 2 max. METHODS Subjects Nine women and nine men from a university in the Midwest participated in the study. Mean age, height, body mass, and body composition were equal to 59.7 ± 6.3 yr, ± 8.8 cm, 83.2 ± 16.4 kg, and 28.6 ± 4.2%, respectively. Inclusionary criteria included age between 50 to 70 yr, those who participated in a moderate intensity exercise program at least 4 days a week for the past 2 months, and those who were low-to-moderate risk according to the ACSM S risk stratification guidelines (2010). Exclusionary criteria included individuals with one or more signs or symptoms of cardiovascular, pulmonary, or metabolic disease (ACSM, 2010). All participants initially filled out a health-history questionnaire and provided their written informed consent. All procedures were approved by the University Institutional Review Board. Procedures All subjects completed an initial familiarization trial on a separate day. Subjects were acquainted with the cycle ergometer by pedaling at W for 5 minutes while wearing the pneumotach face mask. Demographic measurements including height and weight were also recorded in the initial session. The protocol for the study was explained in detail, and participants were reminded that subsequent testing would require a maximal effort. At least 24 h later, subjects were prepared for maximal exercise on the cycle ergometer (Viasprint 150P, Sensormedics Corp., Palm Springs, CA) during which gas exchange data and HR (Polar Electro, Woodbury, NY) were assessed. Before exercise, the metabolic cart (MedGraphics Corporation, St. Paul, MN) was calibrated with gases of known concentration (16%O 2 and 4%CO 2 ) as well as with room air (20.93%O 2 and 0.03%CO 2 ).

7 122 L. C. Dalleck et al. Furthermore, a 3-liter syringe (MedGraphics Cardiorespiratory Diagnostic Systems Calibration Syringe, St. Paul, MN) was used to calibrate flow. Subjects completed 2 min of pedaling at 50 W as a warm-up. During exercise, power output was increased in a steplike manner equal to 5 W/30 s for women and 5 W/20 s for men to elicit volitional fatigue in approximately 7 11 min (Astorino et al., 2004; Yoon, Kravitz, & Robergs, 2007). Pedal cadence was maintained at rev/min, with volitional fatigue representing a failure to sustain pedal cadence greater than 40 rev/min. After the incremental trial, the mouthpiece was removed, and subjects completed an active recovery at 50 Watt for 5 min. Subjects then rested quietly for 1 h in a seated position in the laboratory. During this time, the gas calibration was repeated, and subjects were allowed to ingest water ad libitum. At the end of the rest period, subjects completed the verification test, which consisted of a 2-min warm-up at 50 W followed by a constant load bout to volitional fatigue. The workload of the verification test was equivalent to 105% of the maximal workload elicited during the incremental protocol. Maximal workload was specified as the last fully completed stage of the steplike incremental protocol. The rationale for selection of the 105% workload was that previous research (Astorino et al., 2009) and pilot testing revealed it to be sufficient for eliciting verification test durations of 2 3 min. Similar to the incremental protocol, volitional fatigue during the verification protocol was indicated by failure to sustain pedal cadence greater than 40 rev/min. During exercise, subjects were given verbal encouragement to exercise to volitional fatigue, but they had no indication of the exercise duration or work rate increment of the test. For both trials, gas exchange data were time averaged every 15 s, and VO 2 max for all tests was represented as the mean VO 2 recorded from the last two 15 s samples. Heart rate (HR) was continuously recorded during incremental and verification exercise via telemetry (Polar Electro, Woodbury, NY). In four subjects of similar age and fitness who completed both protocols on four separate days, the within-subject coefficient of variation for incremental and verification VO 2 max was equal to 2.9% and 3.1%, respectively, comparable to values reported elsewhere (Astorino et al., 2009; Howley, Bassett, & Welch, 1995; Midgley et al., 2006). Thus, subjects who revealed a true VO 2 max expressed a VO 2 max from verification testing no more than 3.0% higher than their incremental value. A previously developed HR max criterion for verification testing (< 4 beats min 1 ) was used to help confirm a true VO 2 max (Midgley et al., 2009). Data Analysis All data were analyzed using GraphPad Prism 5.01 (San Diego, CA). Data are reported as mean ± standard deviation (SD) and 95% confidence intervals (CI). A dependent t test was used to examine differences in VO 2 max, HR,

8 Verification Procedure to Confirm VO 2 max 123 gas exchange variables, and protocol duration between the incremental and verification protocol. Statistical significance was established as p < RESULTS Data (mean ± SD) from both tests are reported in Table 1. VO 2 max was similar across protocols (p > 0.05). Differences in VO 2 max between the incremental and constant load, verification protocol ranged from 0.0 to 1.0 ml kg 1 min 1. Sixteen of 18 subjects revealed differences in VO 2 max of less than 3% between protocols. Thus, VO 2 max was confirmed by the verification bout, as their peak VO 2 during this test was within ± 3.0% (the day-to-day error of measuring VO 2 max in our laboratory) of their peak incremental value. Two of 18 subjects exhibited peak VO 2 values between tests greater than ± 3.0% (3.1 and 3.4, respectively), and thus VO 2 max was not confirmed with the verification bout. The individual VO 2 max data for each test (incremental and verification) are presented in Figure 1. The VO 2 response of a representative participant to the incremental and supramaximal tests is revealed in Figure 2. There were no significant differences in ventilation at VO 2 max (p > 0.05) between the incremental and constant load, verification protocol. Likewise, maximal HR and maximal RER were similar (p > 0.05) across protocols. The same 16 of 18 subjects who revealed differences in VO 2 max of less than 3% between testing protocols also fulfilled the HR criterion. Thus, VO 2 max was confirmed by the verification bout, as their peak HR during this test was within ± 4 beats/min of their maximal incremental value. Two of 18 subjects exhibited maximal HR values between tests greater than ± 4 beats min 1 (5 and TABLE 1 Comparison of Responses to Maximal Incremental Exercise Testing and Constant Load, Verification Testing (Mean ± SD) Incremental (N = 18) Verification (N = 18) P value VO 2 max (ml min 1 ) 2329 ± ± % CI VO 2 max (ml kg 1 min 1 ) ± ± % CI V E (L min 1 ) ± ± % CI HR (b min 1 ) ± ± % CI RER 1.17± ± % CI Time (sec) ± ± % CI Incremental exercise test value significantly different from verification test value, p < 0.05.

9 124 L. C. Dalleck et al. FIGURE 1 Comparison of mean incremental test VO 2 max and verification test VO 2 max for all 18 participants. Individual VO 2 max data collected are represented by the line graph. Statistical analysis revealed similar VO 2 max values between the incremental and verification tests (p > 0.05). VO 2 (ml/min) Incremental exercise test Verification bout Time (min) FIGURE 2 VO 2 response to exercise during the incremental exercise test and verification bout protocol for a representative participant. Warm-up data from each protocol have been omitted.

10 Verification Procedure to Confirm VO 2 max beats min 1, respectively), and thus VO 2 max was not confirmed with the verification bout. DISCUSSION This study sought to investigate the utility of verification testing for increasing confidence that a true VO 2 max had been elicited in 18 middle-aged and older adult participants who initially completed incremental cycle ergometry. The primary finding of this study is that compared with the incremental cycle ergometer protocol, verification testing performed 1 h later to volitional exhaustion, revealed a similar VO 2 max. Additionally, maximal HR and maximal RER were also comparable between incremental and verification bouts. Our findings support use of the verification procedure to confirm VO 2 max attainment in middle-aged and older adults completing incremental cycle ergometry. The similarity in mean VO 2 max between the incremental and verification trial corroborates previous findings in runners (Hawkins et al., 2007), male athletes (Midgley et al., 2009), recreationally active men and women (Foster et al., 2007; Niemela et al., 1980; Rossiter et al., 2006), children with spina bifida (degroot et al., 2009), and sedentary men and women (Astorino et al., 2009). The non significant mean difference in VO 2 max equal to 20 ml min 1 (0.8%) revealed between protocols is similar to the range of mean differences (12 to 47 ml min 1 ) reported in previous studies (Foster et al., 2007; Midgley et al., 2006, 2007; Rossiter et al., 2006) that used verification protocols differing in work rate and recovery duration. Nevertheless, as recently emphasized (Noakes, 2008a), verification of VO 2 max attainment is an individual and not group phenomenon, so mean data often reported in the literature (Foster et al., 2007; Hawkins et al., 2007) do not adequately capture individual responses. Furthermore, it has been suggested that using the mean approach could ignore one or more individuals who have not given a maximal effort and therefore probably not elicited a true VO 2 max. Thus, VO 2 max verification criteria always should be applied on an individual basis. Accordingly, a verification peak VO 2 threshold based on the technical error of measurement (±3% for the metabolic cart used in the present study) and peak HR values within 4 beats min 1 of each other were the two criterion measures employed in the present study. Out of the 18 tests, 16 participants satisfied both the VO 2 and HR verification criteria. These results support the utility of a verification procedure to confirm VO 2 max in active middle-aged and older men and women. The traditional requirements applied in the literature for determining attainment of VO 2 max include RER greater than 1.0 to 1.15, maximal heart rate within 10 beats min 1 of age-predicted maximum, and a plateau in VO 2, with up to 13 various definitions found in the literature (Astorino, 2009).

11 126 L. C. Dalleck et al. The majority of data that describe VO 2 max and the criteria for its attainment, however, were developed in studies using young adults (Huggett et al., 2005). Further, previous work (Howley et al., 1995) suggests that achievement of a VO 2 plateau, often considered the gold standard for confirming the measurement of VO 2 max, is frequently not discernible in older adult populations. Thus, a critical issue for the clinician or researcher is whether or not a true VO 2 max has been achieved by the client or participant (Poole et al., 2008). Our findings suggest that the verification procedure may be a preferred criterion for confirming VO 2 max in the older adult population. This has important implications, as it becomes particularly relevant to interpretation of studies using repeated measurements of VO 2 max to establish a training effect or when VO 2 max is used for designing exercise prescriptions. Limitations to the present study merit discussion. The ±3% verification threshold for VO 2 was based on the technical error of measurement in VO 2 determined with the metabolic analyzer in our laboratory. Yet, this criterion threshold warrants further study since it fails to consider an acceptable shortterm, within-subject biological variation in VO 2 max (Midgley et al., 2009). Additionally, our results can be applied only to cycle ergometer exercise, and subjects true VO 2 max may likely be revealed only on the treadmill, as treadmill measurements of VO 2 max are frequently higher than those on the cycle ergometer in nonathletic individuals. Cycle ergometer exercise, however, was the preferred modality for the majority of participants (12 of 18) in the present investigation. CONCLUSION In summary, our findings support use of the verification procedure to confirm VO 2 max attainment in middle-aged and older adults completing incremental cycle ergometry. This is particularly relevant to interpretation of studies that have used repeated measurements of VO 2 max to establish a training effect or when VO 2 max is used for designing exercise prescriptions. Last, present findings can be generalized to only middle-aged and older adults who are physically active and free of chronic conditions such as metabolic syndrome and/or coronary artery disease. Future research is required to verify whether the verification procedure is suitable for chronic diseased individuals and other clinical populations. REFERENCES American College of Sports Medicine (ACSM). (2010) ACSM s guidelines for exercise testing and prescription (8th ed.). Baltimore, MD: Lippincott Williams & Wilkins.

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