This study examined the test-retest reliability of V̇O2max in adolescent V̇O2 plateau achievers and nonachievers. Nineteen male long-distance runners completed a modified Taylor running protocol to volitional fatigue twice within a one-week period. Results showed that 10 subjects did not achieve a plateau in either test (No P), and 9 achieved a plateau in at least one of the tests (P). The V̇O2max differed (p < .05) between tests (Test 1 and Test 2) for the entire sample (Test 1 = 70.4 ± 6.0, Test 2 = 71.7 ± 6.3) but not within the groups (No P, Test 1 = 72.1 ± 4.4, Test 2 = 73.2 ± 4.2; P, Test 1 = 68.5 ± 7.3, Test 2 = 70.1 ± 7.9). V̇O2max was similar for plateau achievers and nonachievers in both Test 1 and Test 2 (p > .05). Interclass correlation coefficients for V̇O2max were high for both the No P (R = .87) and P (R = .97) groups. A high test-retest reliability coefficient for V̇O2max can be obtained even when a plateau in V̇O2 is not achieved.
Anita M. Rivera-Brown, Miguel A. Rivera and Walter R. Frontera
Magnus Dencker, Bianca Hermansen, Anna Bugge, Karsten Froberg and Lars B. Andersen
This study investigated the predictors of aerobic fitness (VO2PEAK) in young children on a population-base. Participants were 436 children (229 boys and 207 girls) aged 6.7 ± 0.4 yrs. VO2PEAK was measured during a maximal treadmill exercise test. Physical activity was assessed by accelerometers. Total body fat and total fat free mass were estimated from skinfold measurements. Regression analyses indicated that significant predictors for VO2PEAK per kilogram body mass were total body fat, maximal heart rate, sex, and age. Physical activity explained an additional 4–7%. Further analyses showed the main contributing factors for absolute values of VO2PEAK were fat free mass, maximal heart rate, sex, and age. Physical activity explained an additional 3–6%.
James Faulkner, Alexis R. Mauger, Brandon Woolley and Danielle Lambrick
To assess the utility of a self-paced maximal oxygen uptake (VO2max) test (SPV) in eliciting an accurate measure of VO2max in comparison with a traditional graded exercise test (GXT) during motorized treadmill exercise.
This was a cross-sectional experimental study whereby recreationally trained men (n = 13, 25.5 ± 4.6 y) completed 2 maximal exercise tests (SPV, GXT) separated by a 72-h recovery period.
The GXT was continuous and incremental, with prescribed 1-km/h increases every 2 min until the attainment of VO2max. The SPV consisted of 5 × 2-min stages of incremental exercise, which were self-selected and adjusted according to 5 prescribed RPE levels (RPE 11, 13, 15, 17, and 20).
Although no significant differences in VO2max were observed between the SPV and GXT (63.9 ± 3.3 cf 60.9 ± 4.6 mL · kg−1 · min−1, respectively, P > .05), the apparent 4.7% mean difference may be practically important. The 95% limits-of-agreement analysis was 3.03 ± 11.49 mL · kg−1 · min−1. Therefore, in the worst-case scenario, the GXT may underestimate measured VO2max as ascertained by the SPV by up to 19%. Conversely, the SPV could underestimate the GXT by 14%.
The current study has shown that the SPV is an accurate measure of VO2max during exercise on a motorized treadmill and may provide a slightly higher VO2max value than that obtained from a traditional GXT. The higher VO2max during the SPV may be important when prescribing training or monitoring athlete progression.
Kristen L. Heck, Jeffrey A. Potteiger, Karen L. Nau and Jan M. Schroeder
We examined the effects of sodium bicarbonate ingestion on the VO2 slow component during constant-load exercise. Twelve physically active males performed two 30-min cycling trials at an intensity above the lactate threshold. Subjects ingested either sodium bicarbonate (BIC) or placebo (PLC) in a randomized. counterbalanced order. Arterialized capillary blood samples were analyzed for pH, bicarbonate concentration ([HCO3 −), and lactate concentration ([La]). Expired gas samples were analyzed for oxygen consumption (VO2). The VO2 slow component was defined as the change in VO2 from Minutes 3 and 4 to Minutes 28 and 29. Values for pH and [HCO3 −] were significantly higher for BIC compared to PLC. There was no significant difference in [La] between conditions. For both conditions there was a significant time effect for VO2 during exercise: however, no significant difference was observed between BIC and PLC. While extracellular acid-base measures were altered during the BIC trial, sodium bicarbonate ingestion did not attenuate the VO2 slow component during constant-load exercise.
Ana Sousa, João Paulo Vilas-Boas, Ricardo J. Fernandes and Pedro Figueiredo
To establish appropriate work intensity for interval training that would elicit maximal oxygen uptake (VO2max) for well-trained swimmers.
Twelve male competitive swimmers completed an incremental protocol to determine the minimum velocity at VO2max (νVO2max) and, in randomized order, 3 square-wave exercises from rest to 95%, 100%, and 105% of νVO2max. Temporal aspects of the VO2 response were examined in these latter.
Swimming at 105% of νVO2max took less (P < .04) absolute time to achieve 90%, 95%, and 100% of VO2max intensities (35.0 ± 7.7, 58.3 ± 15.9, 58.3 ± 19.3 s) compared with 95% (72.1 ± 34.3, 106.7 ± 43.9, 151.1 ± 52.4 s) and 100% (55.8 ± 24.5, 84.2 ± 35.4, 95.6 ± 29.8 s) of VO2max. However, swimming at 95% of νVO2max resulted in longer absolute time (P < .001) at or above the desired intensities (90%: 268.3 ± 72.5 s; 95%: 233.8 ± 74.3 s; 100%: 173.6 ± 78.2 s) and more relative time at or above 95% of VO2max than 105% of νVO2max (68.6% ± 13.5% vs 55.3% ± 11.5%, P < .03), and at or above 100% of VO2max than 100% and 105% of νVO2max (52.7% ± 16.3% vs 28.2% ± 10.5% and 34.0% ± 11.3%, P < .001). At 60 s of effort, swimmers achieved 85.8% ± 11.2%, 88.3% ± 5.9%, and 94.7% ± 5.5% of the VO2max when swimming at 95%, 100%, and 105% of νVO2max, respectively.
When training to elicit VO2max, using higher swimming intensities will promote a faster VO2 response but a shorter time spent above these intensities. However, lower intensities allow maintaining the desired response for a longer period of time. Moreover, using the 60-s time period seem to be a more adequate stimulus than shorter ones (~30-s), especially when performed at 105% of νVO2max intensity.
Anita M. Rivera-Brown, Miguel A. Rivera and Walter R. Frontera
This study examined the effects of three testing protocols on the frequency of achievement of V̇O2max criteria in 13 male adolescent long-distance runners. All subjects completed the modified Taylor (T), Bruce (B), and Taylor intermittent (TI) running protocols on a treadmill to volitional fatigue. The criteria for V̇O2max were (a) respiratory exchange ratio (R) > 1.0, (b) heart rate (HR) >95% predicted max, and (c) increase in V̇O2 < 2.1 ml·kg−1·min−1 with an increase in workload. A plateau was identified in 54%, 39%, and 85% of the subjects during the T, B, and TI protocols, respectively (p < .05). V̇O2 at exhaustion was similar during all protocols (T = 70.8 ± 4.1, B = 71.4 ± 3.5, TI = 69.6 ± 5.0 ml·kg−1-min−1; p > .05). The data suggest that the characteristics of a protocol can determine the frequency of a plateau achievement but have no effect on the attainment of the R or HR criteria. V̇O2 during running exercise to volitional fatigue is independent of testing protocol.
Bumsoo Ahn, Robert McMurray and Joanne Harrell
The relationship between insulin resistance (HOMA-IR), percent body fat, and aerobic fitness (VO2max per unit fat free mass; mL/kgFFM/min) was examined in 1,710 children. Percent body fat was estimated from sum of skinfolds, and VO2max was estimated from submaximal cycle ergometer tests. Overnight fasting blood samples were obtained. VO2max (mL/kgFFM/min) and percent body fat were correlated with HOMA-IR (r=-0.076, p < .002; r=.420, p < .001, respectively); as was VO2max in units of mL/kg/min (r=-0.264, p < .001). When VO2max in mL/kg/min was used, a progressive increase in HOMA-IR was found with decreasing fitness (p < .05). However, when mL/kgFFM/min was used, HOMA-IR scores remained similar between moderate-fit and low-fit group. The stronger association between aerobic fitness (mL/kg/min) and HOMA-IR is partially due to the significant association of fat mass to HOMA-IR. Therefore, our recommendation is to express aerobic fitness in units of mL/kgFFM/min to eliminate the confounding factor of adiposity and better understand the influence of muscle on insulin resistance.
Michael J. Davies, Gail P. Dalsky and Paul M. Vanderburgh
This study employed allometry to scale maximal oxygen uptake (V̇O2 max) by body mass (BM) and lean body mass (LBM) in healthy older men. Ratio standards (ml · kg−1 · min−1) derived by dividing absolute V̇O2 max (L · min−1) by BM or LBM often fail to control for the body size variable. The subjects were 73 older men (mean ± SD: age = 69.7 ± 4.3 yrs, BM = 80.2 ± 9.6 kg, height = 174.1 ± 6.9 cm). V̇O2 max was assessed on a treadmill with the modified Balke protocol (V̇O2 max = 2.2 ± 0.4 L · min−1). Body fat (27.7 ± 6.4%) was assessed with dual energy x-ray absorptiometry. Allometry applied to BM and V̇O2 max determined the BM exponent to be 0.43, suggesting that heavier older men are being penalized when ratio standards are used. Allometric scaling applied to LBM revealed the LBM exponent to be 1.05 (not different from the ratio standard exponent of 1.0). These data suggest that the use of ratio standards to evaluate aerobic fitness in older men penalized fatter older men but not those with higher LBM.
Silvia Pogliaghi, Cecilia Bellotti and Donald H. Paterson
The authors developed and validated a “tailored” version of the Åstrand-Rhyming step test (tA-R) and a new equation for VO2max prediction in older adults (OA). Sixty subjects (age 68 ± 4 yr, 30 male, 30 female) performed their tA-R step test (5-min, 30-cm step, tailored stepping rate) and an incremental cycling test to exhaustion. VO2max was (a) predicted using the standard A-R equation (predictedVO2max), (b) predicted based on the authors’ new multiple linear equation (equationVO2max), and (c) directly measured by incremental cycling test (directVO2max). Agreement among values of VO2max was evaluated by Bland-Altman analysis. The predictedVO2max was not significantly different from the directVO2max, yet with relatively large imprecision. The equationVO2max allowed more precise as well as accurate predictions of VO2max compared with standard A-R prediction. The “tailored” version of the Åstrand-Rhyming step test and the new prediction equation appear suitable for a rapid (5-min), safe (submaximal), accurate, and precise VO2max prediction in healthy OA.
Noé C. Crespo, Geoff D.C. Ball, Gabriel Q. Shaibi, Martha L. Cruz, Marc J. Weigensberg and Michael I. Goran
Acculturation has been implicated to be associated with physical activity (PA) behaviors in adults; little is known, however, with respect to the pediatric population. The purpose of this study was to determine whether cardiorespiratory fitness (VO2max) and/or PA were associated with acculturation status in overweight Hispanic children. In a sample of 144 children 8–13 years old, acculturation status was determined by place of birth: foreign born (n = 17), 1st generation (n = 101), or 2nd/3rd generation (n = 26), and by questionnaire: less assimilated (n = 76) or more assimilated (n = 34). VO2max was measured using a treadmill protocol, PA was assessed by questionnaire, and body composition by DEXA. ANOVA and ANCOVA were used to determine unadjusted and adjusted group differences, respectively. After adjusting for covariates, the 2nd/3rd generation group had significantly higher VO2max compared with the 1st generation group: 2.26 ± 0.20 L/min vs. 2.15 ± 0.19 L/min, p = .03. No differences were noted for PA, however. Acculturation to the U.S. is associated with higher VO2max in overweight Hispanic children. Longitudinal analyses are needed to determine whether these fitness differences confer protective health effects in this at-risk population.