Estimated VO2 Max Research Articles

Do assessments of cardiorespiratory and muscular fitness influence subsequent reported physical activity? A randomized controlled trial

BackgroundRegular physical activity and exercise provide many health benefits. These health benefits are mediated in large part through cardiorespiratory fitness and muscular strength. As most individuals have not had an assessment of their personal cardiorespiratory fitness or muscular strength we investigated if measurements of cardiorespiratory fitness and muscular strength would influence an individual’s subsequent self-reported exercise and physical activity.MethodsVolunteer subjects at a State Fair were randomized in 1:1 parallel fashion to control and intervention groups. The baseline Exercise Vital Sign (EVS) and type of physical activity were obtained from all subjects. The intervention group received estimated maximum oxygen uptake (VO2max) using a step test and muscular strength using a hand grip dynamometer along with age-specific norms for both measurements. All subjects were provided exercise recommendations. Follow up surveys were conducted at 3, 6 and 12 months regarding their EVS and physical activity.ResultsOne thousand three hundred fifteen individuals (656 intervention, 659 control) were randomized with 1 year follow up data obtained from 823 subjects (62.5%). Baseline mean EVS was 213 min/week. No change in EVS was found in either group at follow-up (p = 0.99). Subjects who were less active at baseline (EVS < 150) did show an increase in EVS (86 to 146) at 6 months (p < 0.05). At 3 months the intervention group increased resistance training (29.1 to 42.8%) compared to controls (26.3 to 31.4%) (p < 0.05). Lifestyle physical activity increased in the intervention group at 3 months (27.7 to 29.1%) and 6 months (25%) whereas it declined in the control group at 3 months (24.4 to 20.1%) and 6 months (18.7%) (p < 0.05).ConclusionProviding VO2max estimates and grip strength did not produce an increase in overall physical activity. The EVS and exercise recommendations did however produce an increase in physical activity in less active individuals. In a very active population the VO2max estimate and measured grip strength did increase lifestyle activity and resistance training. Wider adoption of these measures could be effective in promoting physical activity and resistance training.Trial registrationclinicaltrials.gov NCT03518931 Registered 05/08/2018 -retrospectively registered.

Smartphone-Based VO2max Measurement With Heart Snapshot in Clinical and Real-world Settings With a Diverse Population: Validation Study.

BackgroundMaximal oxygen consumption (VO2max) is one of the most predictive biometrics for cardiovascular health and overall mortality. However, VO2max is rarely measured in large-scale research studies or routine clinical care because of the high cost, participant burden, and requirement for specialized equipment and staff.ObjectiveTo overcome the limitations of clinical VO2max measurement, we aim to develop a digital VO2max estimation protocol that can be self-administered remotely using only the sensors within a smartphone. We also aim to validate this measure within a broadly representative population across a spectrum of smartphone devices.MethodsTwo smartphone-based VO2max estimation protocols were developed: a 12-minute run test (12-MRT) based on distance measured by GPS and a 3-minute step test (3-MST) based on heart rate recovery measured by a camera. In a 101-person cohort, balanced across age deciles and sex, participants completed a gold standard treadmill-based VO2max measurement, two silver standard clinical protocols, and the smartphone-based 12-MRT and 3-MST protocols in the clinic and at home. In a separate 120-participant cohort, the video-based heart rate measurement underlying the 3-MST was measured for accuracy in individuals across the spectrum skin tones while using 8 different smartphones ranging in cost from US $99 to US $999.ResultsWhen compared with gold standard VO2max testing, Lin concordance was pc=0.66 for 12-MRT and pc=0.61 for 3-MST. However, in remote settings, the 12-MRT was significantly less concordant with the gold standard (pc=0.25) compared with the 3-MST (pc=0.61), although both had high test-retest reliability (12-MRT intraclass correlation coefficient=0.88; 3-MST intraclass correlation coefficient=0.86). On the basis of the finding that 3-MST concordance was generalizable to remote settings whereas 12-MRT was not, the video-based heart rate measure within the 3-MST was selected for further investigation. Heart rate measurements in any of the combinations of the six Fitzpatrick skin tones and 8 smartphones resulted in a concordance of pc≥0.81. Performance did not correlate with device cost, with all phones selling under US $200 performing better than pc>0.92.ConclusionsThese findings demonstrate the importance of validating mobile health measures in the real world across a diverse cohort and spectrum of hardware. The 3-MST protocol, termed as heart snapshot, measured VO2max with similar accuracy to supervised in-clinic tests such as the Tecumseh (pc=0.94) protocol, while also generalizing to remote and unsupervised measurements. Heart snapshot measurements demonstrated fidelity across demographic variation in age and sex, across diverse skin pigmentation, and between various iOS and Android phone configurations. This software is freely available for all validation data and analysis code.

Does the Multistage 20-m Shuttle Run Test Accurately Predict VO2max in NCAA Division I Women Collegiate Field Hockey Athletes?

Laboratory assessments of maximal oxygen uptake (VO2max) are considered the “gold standard” for ascertaining cardiovascular fitness, but they are not always practical for use in team sport settings. Therefore, the purpose of the current study was to compare the criterion assessment of VO2max on a treadmill to the progressive, multistage 20-m shuttle run test (i.e., Beep test), and to determine the predictability of 6 previously established Beep test predictive equations (i.e., Chatterjee, Flouris, Leger, Leger and Gadoury, Ramsbottom, St. Clair-Gibson). Collegiate women field hockey athletes (n = 65, mean±SD: age 19.6 ± 1.2 years; weight 64.7 ± 6.1 kg) completed criterion VO2max (mean ± SD: 46.4 ± 4.6 mL·kg−1·min−1) and Beep tests to volitional fatigue. According to Bland–Altman and Ordinary Least Products Regressions, the Ramsbottom (46.5 ± 4.2 mL·kg−1·min−1) and Flouris (46.3 ± 3.8 mL·kg−1·min−1) equations were considered valid predictions of criterion measured VO2max (46.4 ± 4.6). The Chatterjee, Leger, Leger and Gadoury, and St. Clair-Gibson equations overestimated VO2max, and are not recommended for use with women collegiate field hockey athletes. The Ramsbottom and Flouris estimates of VO2max from 20-m shuttle performances may be used in this population. For accurate estimates of VO2max, the clientele’s age, fitness level, and training history should be considered when selecting equations.

Validation of a Modified Submaximal Balke Protocol to Assess Cardiorespiratory Fitness in Individuals at High Risk of or With Chronic Health Conditions-A Pilot Study.

Objectives: This study aims to validate a submaximal treadmill walking test for estimation of maximal oxygen consumption (VO2max) in individuals at high risk of or with chronic health conditions.Method: Eighteen participants (age 62 ± 16 years; VO2max 31.2 ± 5.9 ml kg−1 min−1) at high risk of getting or with established chronic diseases performed two valid modified Balke treadmill walking protocols, one submaximal protocol, and one maximal protocol. Test duration, heart rate (HR), and rate of perceived exertion (RPE) were measured during both tests. VO2max was measured during the maximal test. VO2max was estimated from the submaximal test by multiple regression using time to RPE ≥ 17, gender, age, and body mass as independent variables. Model fit was reported as explained variance (R2) and standard error of the estimate (SEE).Results: The model fit for estimation of VO2max from time to RPE ≥ 17 at the submaximal test, body mass, age, and gender was R2 = 0.78 (SEE = 3.1 ml kg−1 min−1, p ≤ 0.001). Including heart rate measurement did not improve the model fit.Conclusions: The submaximal walking test is feasible and valid for assessing cardiorespiratory fitness in individuals with high risk of or chronic health conditions.

Cardiorespiratory fitness in adolescents before and after the COVID-19 confinement: a prospective cohort study.

Long periods of free-movement restrictions may negatively affect cardiorespiratory fitness and health. The present study investigated changes after the COVID-19 confinement in maximal oxygen intake (VO2 max) levels in a sample of 89 Spanish school children aged 12 and 14 years at baseline (49.8% girls). The 20-m shuttle run test served to estimate VO2 max before and after the COVID-19 confinement. Paired t-tests estimated an overall difference of − 0.5 ml.kg−1.min−1 (SD 0.3) (p = 0.12), whereas the highest significant reductions were observed for girls aged 14 years (− 1.5 ml.kg−1.min−1 (SD 0.6) (p < 0.05)). Boys aged 14 years showed a slight increase (0.4 ml.kg−1.min−1 (SD 0.5) (p = 0.44)), whereas boys aged 12 years presented an important decrease (− 1.2 ml.kg−1.min−1 (SD 0.7) (p = 0.14)). Healthy Fitness Zone (HFZ) levels also experienced a decrease of − 3.4% as regards baseline levels over the examined period. All the examined subgroups showed lower levels in relation to a normal VO2 max rate development, although girls aged 14 and boys aged 12 years accounted for the highest part.Conclusion: The results indicate that COVID-19 confinement might delay the normal development of VO2 max in adolescents. Strategies to tackle this concerning decline are warranted. What is Known:• First study analyzing cardiorespiratory fitness levels in teenagers after COVID-19 confinement.What is New:• Important delay in maximal oxygen intake identified in a sample of Spanish teenagers.• These results should be considered to develop strategies of a more active lifestyle in teenagers during and after confinements.

The effect of functional and supportive classic strength trainings in basketball players on aerobic strength, dynamic balance and body composition

Background and Study Aim. It has been aimed to investigate the effects of functional and supportive classic strength trainings in basketball players on aerobic strength, dynamic balance and body composition. Material and Methods. In the study, the test group has performed functional + supportive classic strength training (n=15; 20, 8 ± 1,7 year) three days in a week for eight weeks. Within the process, test and control groups have also continued basketball technical tactics trainings two days in a week. The control group (n=15; 21, 06 ± 1,9 year) has not performed any strength training. The participants have been tested in terms of height, body weight, skinfold calipers, watt bike pro ramp aerobic capacity test and libra see saw balancing board test. When identifying the percentage of body fat, lunge formula has been used. The data has been evaluated with Repetitive Measurements Anova Test. Results. In comparing the group x time interaction, while the developmental difference in the values of VO2max Estimate (mg/kg/min), MET, the percentage of body fat and Left foot lateral balance test has been found out statistically substantial in test and control groups, no significant difference in lateral balance on both feet, right foot lateral balance the measurements and transfer balance measurements on both feet has been found out. Conclusions. As a consequence, it has been seen that functional and supportive strength trainings have contributed to the percentage of body fat, aerobic capacity and dynamic balance. In the planning of yearly training it has been seen that functional strength trainings in preparation phase will contribute to the development levels of basketball players.

Development of multistage 10-m shuttle run test for VO2max estimation in healthy adults

Background and objective: The disadvantage of the traditional 20-m multistage shuttle run test (MST) is that it requires a long space for measurements and does not include various age groups to develop the test. Therefore, we developed a new MST to improve the spatial limitation by reducing the measurement to a 10-m distance and to resolve the bias via uniform distributions of gender and age. Material and methods: Study subjects included 120 healthy adults (60 males and 60 females) aged 20 to 50 years. All subjects performed a graded maximal exercise test (GXT) and a 10-m MST at five-day intervals. We developed a regression model using 70% of the subject's data and performed a cross-validation test using 30% of the data. Results: The male regression model's coefficient of determination (R2) was 58.8%, and the standard error of estimation (SEE) was 4.17 mL/kg/min. The female regression model's R2 was 69.2%, and the SEE was 3.39 mL/kg/min. The 10-m MST showed a high correlation with GXT on the VO2max (males: 0.816; females: 0.821). In the cross-validation test for the developed regression models, the male's SEE was 4.38 mL/kg/min, and the female's SEE was 4.56 mL/kg/min. Conclusion: Thus, the 10-m MST is an accurate and valid method for estimating the VO2max. Therefore, the 10-m MST developed by us can be used when the existing 20-m MST cannot be used due to spatial limitations and can be applied to both men and women in their 20s and 50s.

Validation of Garmin Fenix 3 HR Fitness Tracker Biomechanics and Metabolics (VO2max)

The purpose of this study was to determine the validity of the Garmin fēnix® 3 HR fitness tracker. Methods: A total of 34 healthy recreational runners participated in biomechanical or metabolic testing. Biomechanics participants completed three running conditions (flat, incline, and decline) at a self-selected running pace, on an instrumented treadmill while running biomechanics were tracked using a motion capture system. Variables extracted were compared with data collected by the Garmin fēnix 3 HR (worn on the wrist) that was paired with a chest heart rate monitor and a Garmin Foot Pod (worn on the shoe). Metabolic testing involved two separate tests; a graded exercise test to exhaustion utilizing a metabolic cart and treadmill, and a 15-min submaximal outdoor track session while wearing the Garmin. 2 × 3 analysis of variances with post hoc t tests, mean absolute percentage errors, Pearson’s correlation (R), and a t test were used to determine validity. Results: The fēnix kinematics had a mean absolute percentage errors of 9.44%, 0.21%, 26.38%, and 5.77% for stride length, run cadence, vertical oscillation, and ground contact time, respectively. The fēnix overestimated (p &lt; .05) VO2max with a mean absolute percentage error of 8.05% and an R value of .917. Conclusion: The Garmin fēnix 3 HR appears to produce a valid measure of run cadence and ground contact time during running, while it overestimated vertical oscillation in every condition (p &lt; .05) and should be used with caution when determining stride length. The fēnix appears to produce a valid VO2max estimate and may be used when more accurate methods are not available.

Comparison of the Ekblom-Bak Submaximal Test to a Maximal Test in a Cohort of Healthy Younger and Older Adults in the United States.

Cardiorespiratory fitness (CRF) is routinely investigated in diverse populations, including in older adults of varying physical activity levels. Commonly performed maximal exercise testing protocols might be contraindicated and/or inadequate for older individuals who have physical or cognitive impairment. Moreover, early termination of an attempted maximal exercise test could result in underestimation of CRF in this population. The goal of the current study was to compare CRF estimates using the Ekblom-Bak (EB) submaximal exercise test – previously validated in a cohort of Scandinavian adults – versus a subsequent maximal exercise test in a diverse, Midwestern United States cohort. Fifteen generally healthy individuals were included in this study who were either “Young” (25–34 years old) or “Older” (55–75 years old) as well as either sedentary or highly active. Participants completed the EB submaximal exercise test, followed immediately by a maximal exercise test. We found that all 15 individuals were able to successfully perform the EB submaximal testing method. Across the wide range of volumes of maximal oxygen consumption (VO2max; 12–52 ml/kg/min), the EB submaximal estimates of VO2max correlated highly with the maximal test based values (Pearson’s r = 0.98), but with a small bias (6 ml/kg/min, 95% limits of agreement −1.06 and −11.29). Our results suggest that the EB submaximal testing method may be useful in identifying wide differences in CRF among a diverse cohort of older adults in the United States, but larger studies will be needed to determine the degree of its accuracy and precision in identifying smaller differences.

Cardiorespiratory Fitness of Firefighters: Initial Results of a Multi-Phased Study.

Objective:To address which body composition (BC) measures best correlate with cardiorespiratory fitness (CRF) in firefighters and develop a model for accurate CRF estimation compared with traditional methods.Methods:Career firefighters had body mass index (BMI) and waist circumference (WC) measured in addition to body fat percentage (FM%) by dual-energy x-ray absorptiometry (DXA). CRF as maximum oxygen uptake (VO2max) was estimated by rowing machine and measured by indirect calorimetry in a treadmill exercise test.Results:Fifty two firefighters participated (92.3% men). Univariate correlations with BMI were best with WC. Univariate correlations with VO2max were best with FM%. Obesity classifications by BC measures agreed weakly at best. Multivariate analysis of several variables yielded an improved VO2max estimate (R2 = 0.70).Conclusions:Fire departments may benefit from more sophisticated measures of BC and CRF to evaluate firefighter fitness.

Frequency And Mode Of Physical Activity Influence Gut Microbial Composition In Overweight And Obese Adults

Chronic diseases are linked to adverse phylogenetic and functional alterations in the gut microbiota. Physical activity (PA) regimens may provide a low-cost and practical means to improve “gut health” in individuals at-risk of developing chronic disease. Endurance exercise has been shown to alter gut microbial composition in heavier sedentary individuals but it is not known how other PA modes impact the gut microbiota. It is hypothesized that PA mode and frequency may underlie differences in the gut microbiota in heavier adults. PURPOSE: To examine the relationship between PA measures and gut microbial richness and evenness and composition in overweight and obese adults. METHODS: Adults (n=38), 28-55 years old with BMI 27-36 kg·m-2 were asked about their frequency of aerobic, strength, and stretching exercise during one week. Participants were measured for their age-predicted VO2 max using a modified Bruce protocol on a treadmill. DNA was extracted from self-collected fecal samples for Illumina MiSeq amplicon sequencing of 16S rRNA V4. Sequencing reads were processed according to MOTHUR standard operating procedures, with operational taxonomic unit assignment at the 97% similarity threshold. General linear models were used to test effect of PA measures on alpha diversity indices. Distance-based redundancy analyses were used to evaluate community composition in relation to PA measures. RESULTS: Shannon and Simpson indices did not differ by estimated VO2 max nor by PA frequency and mode (p > 0.05). Frequency and mode of PA explained more variability in the gut microbial community (11.6%) than estimated VO2 max (1.9%). Community patterns were not explained by estimated VO2 max (ρ = 0.81). However, PA frequency and mode did explain community patterns with the frequency of strength training during the week showing a greater impact (ρ < 0.01) than aerobic (ρ = 0.66) and stretching exercise (ρ = 0.72). CONCLUSIONS: PA frequency and mode exhibit greater impacts on the gut microbial community structure than cardiorespiratory fitness in overweight and obese adults. In particular, the incorporation of strength exercise may have a larger impact on the gut microbial community than previously thought. Supported by Montana State University Research Initiative 51040-MUSRI2015-03 and USDA-NIFA 2017-67018-26367.

Fitness Levels In College-aged Females: A 20-year Follow-up

PURPOSE: A decline in fitness levels of both children and young adults has been reported over the last two decades. The purpose of this study was to determine to what extent this claim is true, and which components of fitness may be involved in this decline. METHODS: Researchers examined several components of fitness, including estimated cardiorespiratory fitness, muscular fitness, percent body fat, and body max index (BMI) during 1999. Subjects for the original study were 72 college females enrolled in general education fitness classes. The assessment was repeated at the same university in 2019 with 69 college females, also enrolled in general education fitness classes. During both time periods, students were assessed at the beginning of the course using the Queens College Step Test to estimate cardiorespiratory fitness, the YMCA bench press test to assess muscular fitness, and 3-site skinfolds to estimate percent body fat. Height and weight were measured to calculate BMI. Data were analyzed using independent measures t-tests to evaluate differences between the 1999 and 2019 groups. Participants were also categorized as normal weight/overweight and obese/nonobese, and Pearson chi-square evaluated significant differences in those categories from 1999 to 2019. RESULTS: Participants were significantly higher in percent fat (25.45 ± 0.72%) in 2019 than in 1999 (22.97 ± 0.71%; p=0.0149). Performance on the YMCA bench press test decreased in 2019 (11.78 ± 9.48 reps) compared with the same test in 1999 (23.7 ± 9.37 reps; p<0.0001). BMI was statistically the same from 1999 to 2019 (22.79 ± 0.43 kg/m2 in 1999 vs. 22.90 ± 0.44 in 2019; p=0.86), as was estimated VO2 max in ml/kg/min (35.72 ± 0.42 in 1999 vs. 36.20 ± 0.43 in 2019; p=0.4258). Although BMI was statistically the same during both years, the percent of students who were obese (BMI > 30) increased from 2 out of 72 (2.78%) in 1999 to 5 out of 69 (7.24%) in 2019. According to the Pearson chi-square test, this was not a significant difference in BMI classification (p=0.2682). CONCLUSIONS: According to this study, college females have increased in percent body fat and decreased in muscular fitness in the past 20 years.

ACSM And FRIEND Running Equations, Are They Valid For Healthy Active Women?: Preliminary Results

VO2max is simply defined by the body’s ability to use oxygen during physical exercise and is widely used as an indicator of cardiorespiratory fitness. Lower VO2max is associated with higher risk of morbidity and mortality as well as low performance while higher VO2max predict good performance in aerobic sports. Direct measurement of VO2max is still the gold standard, however this method presents high cost and required sophisticated equipment. Therefore, several metabolic equations have been developed to estimate VO2max using indirect calculation. The most commonly used equations are those developed by the American College of Sport Medicine (ACSM) and the research group of Fitness Registry and the Importance of Exercise National Database (FRIEND). PURPOSE: The aim of this study is to evaluate the accuracy of these two equations to estimate VO2max comparatively to direct O2 consumption measurement. METHODS: 21 healthy active women aged between 22-50y.o. (mean: 37,1±7,4)(BMI: 23,0±2,5kg/m2) performed a maximal treadmill test using a metabolic cart (Vyntus CPX) to measure direct VO2max (mlO2/kg/min). VO2max estimation was then calculated using ACSM and FRIEND running metabolic equations. Results were compared using repeated measures T-test. These preliminary results are part of a larger study which includes 180 men and women of all age group and fitness level (18-34, 35-54 and ≥ 55y.o.). RESULTS: When compared to the direct measurement (Vyntus: 44,9±4,9), only the ACSM equation showed significantly higher results 53,0±6,6)(mean difference: 8,1; p<0,01). The FRIEND equation did not significantly differ from the metabolic cart result (45,5±4,7)(mean difference: 0,56; p=0,5). In the same direction, ACSM showed a large effect size (Hedge’s g = 1,29) while Friend only showed a small effect size (g = 0,11). CONCLUSION: The VO2max calculated with the ACSM equation for running showed overestimated values in our female sample. The average difference between direct and indirect measurement when using the FRIEND equation suggests a better accuracy. More research is needed to evaluate the accuracy in different populations and different fitness level to optimize the VO2 estimation formula.

Metabolic Equations To Estimate Vo 2 Max Of Healthy Active Canadian Men Aged 18-34 Years-old: Preliminary Results

VO2max is simply defined by the body’s ability to use oxygen during physical exercise and is widely used as an indicator of cardiorespiratory fitness. Lower VO2max is associated with higher risk of morbidity and mortality as well as low physical performance while higher VO2max levels predict good performance in aerobic sports. Direct measurement of VO2max is still considered as the gold standard. However, it is costly, required sophisticated equipment, and less accessible. Therefore, several metabolic equations have been developed to estimate VO2max using indirect calculation in sub maximal tests. The most commonly used equations are those developed by the American College of Sport Medicine (ACSM) and the research group of Fitness Registry and the Importance of Exercise National Database (FRIEND). PURPOSE: This study aims to evaluate the accuracy of these two equations to estimate VO2max comparatively to direct O2 consumption measurement. METHODS: 30 healthy active men aged between 18-34 years old (BMI: 23,9±2,9 kg/m2) who are avid runners performed a maximal treadmill test with direct VO2 measures (mlO2/kg/min) using a metabolic cart (Vyntus CPX). VO2max estimation was calculated using ACSM and FRIEND running metabolic equations. Direct and indirect results were compared with repeated measures T-test. These preliminary results are part of a larger study which includes 180 men and women of all age group (18-34, 35-54, and ≥ 55y.o.). RESULTS: Indirect VO2max obtained from ACSM and FRIEND equations showed very large (d = 2.01) and moderate (d = 0.6) effect size, and were significantly different when compared to direct measures (ACSM: 66,4±7,0; FRIEND: 56,5±5,9; Vyntus: 53,0±6,3; p<0,001). The mean ACSM overestimation was 13,4 mlO2/kg/min while FRIEND equation was only 3,5 mlO2/kg/min. CONCLUSION: The VO2max calculated with ACSM and FRIEND equations for running showed overestimate values in our male sample. However, the average difference between direct and indirect measurement is smaller when using the FRIEND equation suggesting better accuracy. More research is needed to evaluate the accuracy in different populations and different fitness levels to optimize the VO2max estimation formula.

Shuttle Run And Performance In Aerobic And Anaerobic Capacities.

Field hockey is a physiologically demanding sport with intermittent bouts of aerobic and anaerobic performance. The ability to assess player condition is vital to coaching success. In place of VO2,the 20-meter shuttle run test (SRT) is a common alternative for on field determination of a player's aerobic fitness. Limited data supports the relationship between shuttle run and anaerobic fitness in this population. PURPOSE: To determine the accuracy of a shuttle run test (SRT) as a predictor of field hockey performance. METHODS: We enrolled19 D1 field hockey players (18-22 years old) in an 11-week prospective study. Goalies and injured players were excluded from the study. A 6-week program prior to the study consisted of a 20m shuttle run during practice. Speed was gradually increased by 0.5 km/h at a time, each increase in running speed was coded as a change in level. A Polar Pro GPS/heart rate recorder (Polar Electro Inc. Bethpage, NY) recorded effort parameters during 43 practices. Data included time in heart rate (HR) zone 4 (80-89%) (sec), time in HR zone 5 (90-100%) (sec), percentage of HR max (%) total distance covered (m), distance/min (m/min), maximum speed (km/h), number of sprints (acceleration >1.9 m/s2), and distance in speed zone 5 (>19.00 km/h) (m). Bivariate correlations and linear regressions tested relationships between SRT and on-field performance. RESULTS: SRT was significantly related to total distance covered (r=0.090, p=0.022), distance per minute (r=0.112, p=0.004), maximum speed (r=0.097, p=0.013), distance in speed zone 5 (r=0.119, p=0.002), and number of sprints (r=0.188, p<0.001). No other relationships were detected. Better performance on the SRT corresponded to more (and more frequent) in-practice sprinting. CONCLUSION: Although the SRT may not provide a valid estimate of VO2 max, it is a valid predictor for many components of on-field performance. It associates with total distance, distance per minute, maximum speed, distance in speed zone 5, and number of sprints in collegiate field hockey players.

A Comparison Of Step Tests To Predict Maximal Oxygen Consumption

INTRODUCTION: Of the many methods to estimate maximal oxygen consumption (VO2max), step tests provide a quick estimation of VO2max without expensive equipment. Few studies have investigated varied step height and cadence speed across a broad sample population. The purpose of this study was to generate and validate models to predict VO2max using three different step tests. METHODS: A sample of 162 adults, aged 18-79 years, completed a graded exercise test to assess VO2max. All three step tests were completed on a later day. The step tests differed in duration, number of stages, and step height. Test 1 (T1) was a two-stage, six-minute test, and had a six-inch step height, Test 2 (T2) was a three-stage, nine-minute test, and had a six-inch step height, and Test 3 (T3) was a three-stage, nine-minute test, and had an eight-inch step height. Stepping cadence increased with each stage and was prescribed based on age group (<40 years, 40-60 years, and >60 years). Recovery heart rate (HRrec) was measured every 30-seconds for two-minutes after each test. Model equations were obtained using hierarchal multiple regression analysis. Covariates for each model included age, sex, body mass, stepping cadence, and HRrec at all measured time intervals. The baseline model for each test consisted of age, sex, and body mass. Stepping cadence was entered in step two but was only significant for T3. Thirty-second HRrec was entered in the final step and was significant for all three tests. Validity was assessed using a Jackknife cross-validation method, allowing for root mean square error (RMSE) and percent bias to be calculated. RESULTS: The baseline model accounted for ~72% of the variance for predicting VO2max. Each model accounted for ~83% of VO2max variance and had an error ~4.15 ml.kg-1.min-1. The results of the jackknife analysis found that bias for all three tests was minimal (<0.001%) and the resulting bias-adjusted R2 was 0.825, 0.826, and 0.834 for T1, T2, and T3, respectively. Adjusted RMSE was 4.259, 4.223, and 4.102 ml.kg-1.min-1 for T1, T2, and T3, respectively. DISCUSSION: All three step tests account for ~83% of the variance of VO2max with an error around 4.2 ml.kg-1.min-1. As there is a minimal difference between tests, there is flexibility in the utilization of these step tests based on the need of the administrator and ability of the client.

Effects Of High Intensity Physical Exercise On Short-term Memory In University Students

Studies have determined that physical training provides benefits in people's physical health. Physical exercise is one of the most powerful lifestyle to positively affect the adult brain and emerging evidence points to high intensity interval training (HIIT) as an effective way to improve various aspects of brain function among them the improvement of cognition and short-term memory. PURPOSE: To analyze the effects of (HIIT) in university students on short-term memory. METHODS: 22 university athletes (Mage=21.6, SD= 1.5), (n=11 experimental group), (n=11 control group). A HIIT program of 12 sessions of short-term (3 weeks) and 6 sessions of short-term memorization was applied. Maximum oxygen consumption (VO2max) was estimated through the Course Navette Test and memory evaluation through a Rey Auditory Verbal Learning Test (RAVLT). The instruments used for the investigation was a Polar H10® band. A t student test for paired samples was applied by IBM SPSS v.22 (p. <0.001). RESULTS: The maximum heart rate (HRmax) of the control group obtained a value of M=199.9, SD= 15ppm and the experimental group M=195, SD=6.7ppm. In the third week of intervention results were found statistically significant. CONCLUSION: After twelve training sessions of high intensity physical exercise (HIIT), statistically significant results were obtained, in relation to high intensity physical effort with short-term memory. For future research it is recommended to implement a greater number of training and memory sessions. Limitations of this study include indirect VO2max estimation and a small sample size. Keywords: short-term memory, university students, high intensity interval training.

HIIT PROGRAM EFFECTS IN CAPILLARY BLOOD LACTATE LEVELS

In the last decade, high intensity interval training (HIIT) has been shown to be an appropriate alternative to moderate-intensity, continuous exercise for improving cardiorespiratory fitness. HIIT protocols typically result in high blood lactate (La) levels. However, accumulated lactic acid is a potent metabolic stimulus, which plays a major role in the control of physiological adaptations. Therefore, it may be essential for improvements in endurance performance. The literature indicates that there is a strong positive relationship between maximum oxygen consumption (VO2max) and La production. PURPOSE: To investigate changes in La levels after 4 weeks of HIIT program. METHODS: Blood samples were collected from five female and five male student-athletes (n= 10) (Mage=21, SD=0.95). A short-term (4 weeks) HIIT protocol used and VO2max calculated through Course-Navette Test. The instruments used for this research were an Accutrend Plus-Roche lactometer and BM-Lactate test strips (Risch-Rotkreuz, Switzerland). The analysis consisted of t student tests for paired samples in IBM SPSS v.25 (p <0.001). RESULTS: VO2max and blood La changed significantly in six participants (Pre-La M=11.65mmol/L; Post-La M=9.41mmol/L). The participants that achieved to increase their VO2max, produced lower amounts of capillary blood La. CONCLUSION: Using HIIT, our study results confirm the positive relationship of VO2max and La. The inferences of these preliminary results could be used in future, larger-scale interventions concerning ways to affect La production through the increase of VO2max using a HIIT program. Future studies should further investigate anaerobic threshold modification processes through different training programs, such as Repeated Sprint Training (RST), Sprint Interval Training (SIT) and Moderate Intensity Continuous Training (MICT). Limitations of this study include small sample size and indirect VO2max estimation. Keywords: High-Intensity Interval Training, maximal oxygen consumption, lactate

Modification of Cooper’s 12-min Run Test to Predict Maximum Oxygen Uptake in Indian Cricketers

Cooper’s 12-minute run test (CRT) for prediction of maximum oxygen uptake (VO2max) has not yet been explored in Indian sportspersons. Present investigation was conducted to evaluate the applicability of CRT in Indian cricketers. 75 male and 45 female cricket players were randomly recruited from reputed cricket academies of Kolkata, India and were randomly assigned into the study group (male = 45, female = 25) and confirmatory group (male = 30, female = 20). Incremental cycle ergometer exercise was used for direct estimation of VO2max by expired gas analysis and the indirect prediction of VO2max (PVO2max) was performed by CRT method. The current protocol of CRT was found to be inapplicable in both the genders of Cricketers due to a significant difference between PVO2max and VO2max and a large limit of agreement between PVO2max and VO2max in the study groups. A significant correlation (r = 0.76 in males and r = 0.79 in females, p&lt;0.001) was depicted between VO2max and distance covered in CRT. Regression equations were computed based on the significant correlation. The application of these equations in the confirmatory groups revealed an insignificant difference between PVO2max and VO2max and narrow limits of agreement. Standard errors of the estimate of the regression norms were also minimal. Therefore, modified equations are recommended for CRT application for valid and precise evaluation of cardiorespiratory fitness in terms of VO2max in male and female Indian cricketers.

A Clinical Method for Estimation of VO2max Using Seismocardiography

The purpose of this study was to investigate the correlation between the seismocardiogram and cardiorespiratory fitness. Cardiorespiratory fitness can be estimated as VO2max using non-exercise algorithms, but the results can be inaccurate. Healthy subjects were recruited for this study. Seismocardiogram and electrocardiogram were recorded at rest. VO2max was measured during a maximal effort cycle ergometer test. Amplitudes and timing intervals were extracted from the seismocardiogram and used in combination with demographic data in a non-exercise prediction model for VO2max. 26 subjects were included, 17 females. Mean age: 38.3±9.1 years. The amplitude following the aortic valve closure derived from the seismocardiogram had a significant correlation of 0.80 (p<0.001) to VO2max. This feature combined with age, sex and BMI in the prediction model, yields a correlation to VO2max of 0.90 (p<0.001, 95% CI: 0.83-0.94) and a standard error of the estimate of 3.21 mL·kg-1·min-1 . The seismocardiogram carries information about the cardiorespiratory fitness. When comparing to other non-exercise models the proposed model performs better, even after cross validation. The model is limited when tracking changes in VO2max. The method could be used in the clinic for a more accurate estimation of VO2max compared to current non-exercise methods.