Relationships between HR and (.)VO(2) in the obese

Are incremental exercise relationships between rating of perceived exertion and oxygen uptake or heart rate reserve valid during steady-state exercises?

Background

Rating of perceived exertion (RPE) is considered a valid method for prescribing prolonged aerobic steady-state exercise (SSE) intensity due to its association with physiological indicators of exercise intensity, such as oxygen uptake (V̇O2) or heart rate (HR). However, these associations between psychological and physiological indicators of exercise intensity were found during graded exercise tests (GXT) but are currently used to prescribe SSE intensity even though the transferability and validity of the relationships found during GXT to SSE were not investigated. The present study aims to verify whether (a) RPE-HR or RPE-V̇O2 relations found during GXTs are valid during SSEs, and (b) the duration and intensity of SSE affect these relations.

Methods

Eight healthy and physically active males (age 22.6 ± 1.2 years) were enrolled. On the first visit, pre-exercise (during 20 min standing) and maximal (during a GXT) HR and V̇O2 values were measured. Then, on separate days, participants performed 4 SSEs on the treadmill by running at 60% and 80% of the HR reserve (HRR) for 15 and 45 min (random order). Individual linear regressions between GXTs' RPE (dependent variable) and HRR and V̇O2 reserve (V̇O2R) values (computed as the difference between maximal and pre-exercise values) were used to predict the RPE associated with %HRR (RPEHRR) and %V̇O2R (RPEV̇O2R) during the SSEs. For each relation (RPE-%HRR and RPE-%V̇O2R), a three-way factorial repeated measures ANOVA (α = 0.05) was used to assess if RPE (dependent variable) was affected by exercise modality (i.e., RPE recorded during SSE [RPESSE] or GXT-predicted), duration (i.e., 15 or 45 min), and intensity (i.e., 60% or 80% of HRR).

Results

The differences between RPESSE and GXT-predicted RPE, which were assessed by evaluating the effect of modality and its interactions with SSE intensity and duration, showed no significant differences between RPESSE and RPEHRR. However, when RPESSE was compared with RPEV̇O2R, although modality or its interactions with intensity were not significant, there was a significant (p = 0.020) interaction effect of modality and duration yielding a dissociation between changes of RPESSE and RPEV̇O2R over time. Indeed, RPESSE did not change significantly (p = 0.054) from SSE of 15 min (12.1 ± 2.0) to SSE of 45 min (13.5 ± 2.1), with a mean change of 1.4 ± 1.8, whereas RPEV̇O2R decreased significantly (p = 0.022) from SSE of 15 min (13.7 ± 3.2) to SSE of 45 min (12.4 ± 2.8), with a mean change of -1.3 ± 1.5.

Conclusion

The transferability of the individual relationships between RPE and physiological parameters found during GXT to SSE should not be assumed as shown by the results of this study. Therefore, future studies modelling how the exercise prescription method used (e.g., RPE, HR, or V̇O2) and SSE characteristics (e.g., exercise intensity, duration, or modality) affect the relationships between RPE and physiological parameters are warranted.

Bayesian Analysis of the HR-VO2 Relationship during Cycling and Running in Males and Females

Professional organizations advise prescribing intensity of aerobic exercise using heart rate reserve (%HRR) which is presumed to have a 1:1 relationship with either maximal oxygen uptake (%VO₂max) or %VO₂ reserve (%VO₂R). Even though running and cycling are popular modes of training, these relationships have not been investigated in a group of males and females during both running and cycling. This study evaluated the %HRR-%VO₂max and %HRR-%VO₂R relationships in 41 college-aged males (n = 21) and females (n = 20) during treadmill running and cycling. Heart rate (HR) and VO₂ data were collected at rest and during maximal exercise tests on a treadmill and cycle ergometer. The HR and VO₂ data were analyzed using a Bayesian approach. Both the %HRR-%VO₂max and %HRR-%VO₂R relationships did not coincide with the line of identity in males and females in both treadmill running and cycling. %HRR was closer to %VO₂max than to %VO₂R. There were no significant differences in the intercepts of the %HRR-%VO₂max and %HRR-%VO₂R relationships between males and females during running or cycling, or between running and cycling in males or females. The credible intervals of the intercepts and slopes suggest interindividual variability in the HR-VO₂ relationship that would yield significant error in the prescription of intensity of aerobic exercise for an individual.

Effect of individual characteristics and aerobic training on the %HRR-%V˙O2R relationship

This study aimed to assess if, during incremental exercise, considering individual characteristics can make the relationship between the percentages of heart rate (HRR) and oxygen uptake (VO₂R) reserve either 1:1 or more accurate. Cycle ergometer data of the maximal incremental exercise tests performed by 450 healthy and sedentary participants (17-66 years) of the HERITAGE Family Study, grouped for sex, ethnicity, age, body fat, resting HR, and VO_2max, were used to calculate the individual linear regressions between %HRR and %VO₂R. The mean slope and intercept of the individual linear regressions of each subgroup were compared with 1 and 0 (identity line), respectively, using Hotelling tests followed by post-hoc one-sample t-tests. Two multiple linear regressions were also performed, using either the slopes or intercepts of the individual linear regressions as dependent variables and sex, age, resting HR, and VO_2max as independent variables. The mean %HRR-%VO₂R relationships of all subgroups differed from the identity line. Moreover, individual linear regression intercepts (8.9±16.0) and slopes (0.971±0.190) changed (p<0.001) after 20 weeks of aerobic training (13.1±11.1 and 0.891±0.122). The multiple linear regressions could explain only 3.8% and 1.3% of the variance in the intercepts and slopes, whose variability remained high (standard error of estimate of 15.8 and 0.189). In conclusion, the %HRR-%VO₂R relationship differs from the identity line regardless of individual characteristics and their difference increased after aerobic training. Moreover, due to the high interindividual variability, using a single equation for the whole population seems not suitable for representing the %HRR-%VO₂R relationship of a given subject, even when several individual characteristics are considered.

Systematic Review and Meta-Analysis of the Relationship between Actual Exercise Intensity and Rating of Perceived Exertion in the Overweight and Obese Population

The number of overweight (OW) and obese (OB) children, adolescents, and adults has increased globally. Exercise intensity, both actual and perceived, is a significant factor in a variety of health-related investigations and rehabilitation trainings. Despite this, literature on the connection between actual exercise intensity and the rating of perceived exertion (RPE) in overweight and obese populations is lacking. A systematic review, meta-analysis, combined analysis of variance (Brown-Forsythe ANOVA), and Spearman correlation were performed to fill this gap. After preliminary assessments, ten studies were classified as having a low risk of bias and a degree of heterogeneity (I² = 34%; p = 0.05). The RPE scores (F = 0.032; p = 0.859), physiological index (percentage of maximal heart rate (%HR_max) (F = 0.028; p = 0.869), and percentage of maximal oxygen uptake (%VO_2max) (F = 2.434; p = 0.136) demonstrated consistency without being significantly different between the normal weight (NW) and OW/OB groups. The RPE scores varied by age (NW (coefficient values) = 0.677 ***, OW = 0.585 **), as well as by indoor temperature (OW only, coefficient values = 0.422 *), body mass index (NW (coefficient values) = 0.516 **, OW = 0.580 **), and test time (NW only, coefficient values = 0.451 *). We conclude that RPE is appropriate for the following OW and OB people: (1) those who are older than 21.5 (the lowest age in the group of ≥18) years old and younger than 58.6 (the highest age in the group of ≥18) years old, without any other diseases, and (2) those who engage in low-intensity exercise while maintaining a standard indoor temperature. Future studies may address alternative techniques for increasing the reliability of longitudinal comparisons and gender comparisons, as well as investigate other possible confounding factors.

The effects of breaking sedentary time with different intensity exercise bouts on energy metabolism: A randomized cross-over controlled trial

BACKGROUND AND AIMS

Breaking up sedentary periods, particularly with light activity, increases total energy expenditure (EE), and helps provide better glycemic control. However, the effects of activities of various intensities to interrupt prolonged sedentary time are unclear. The purpose of the present study was to examine potential differences in glycemic control and EE from breaking up sedentary time with short exercise bouts of different intensities.

METHODS AND RESULTS

Nine overweight/obesity young men underwent whole body indirect calorimetry at 19:00 on day 1 and stayed overnight. After awakening on day 2, they performed short duration jogging every 30 min over 8 h (16-time bouts in total) under 3 different conditions with the same running distance: (1) lactate threshold (LT) for 2 min, (2) 60% LT for 200 s, and (3) onset of blood lactate accumulation (OBLA) for 75 s. The 24-h EE and interstitial glucose concentration (from 8:00 to 19:00 on day 2) was continuously measured throughout the trials. The standard deviation during intervention and indexes of postprandial of the interstitial glucose concentration was significantly lower at LT and OBLA than at 60% LT (p < 0.05). The 24-h EE was not significantly different among conditions, but EE at OBLA during intervention was slightly but significantly higher than at 60% LT and LT.

CONCLUSION

Breaking up sedentary time with short-duration jogging at LT and with OBLA intensities may have better glycemic control and increased use of carbohydrate as a fuel, while short-duration a jogging at OBLA intensity may increase EE.

TRIAL REGISTRATION

UMIN000041361.

HRR and V˙O2R Fractions Are Not Equivalent: Is It Time to Rethink Aerobic Exercise Prescription Methods?

INTRODUCTION

According to current guidelines, the intensity of health-enhancing aerobic exercise should be prescribed using a percentage of heart rate reserve (%HRR), which is considered to be more closely associated (showing a 1:1 relation) with the percentage of oxygen uptake reserve (%V˙O2R) rather than with the percentage of maximal oxygen uptake (%V˙O2max) during incremental exercise. However, the associations between %HRR and %V˙O2R and between %HRR and %V˙O2max are under debate; hence, their actual relationships were investigated in this study.

METHODS

Data from each stage of a maximal incremental exercise test performed by 737 healthy and physically inactive participants of the HERITAGE Family Study were screened and filtered then used to calculate the individual linear regressions between %HRR and either %V˙O2R or %V˙O2max. For each relationship, the mean slope and intercept of the individual linear regression were compared with 1 and 0 (i.e., the identity line), respectively, using one-sample t-tests. The individual root mean square errors of the actual versus the 1:1 predicted %HRR were calculated for both relationships and compared using a paired-sample t-test.

RESULTS

The mean slopes (%HRR-%V˙O2R, 0.972 ± 0.189; %HRR-%V˙O2max, 1.096 ± 0.216) and intercepts (%HRR-%V˙O2R, 8.855 ± 16.022; %HRR-%V˙O2max, -3.616 ± 18.993) of both relationships were significantly different from 1 and 0, respectively, with high interindividual variability. The average root mean square errors were high and revealed that the %HRR-%V˙O2max relationship was more similar to the identity line (P < 0.001) than the %HRR-%V˙O2R relationship (7.78% ± 4.49% vs 9.25% ± 5.54%).

CONCLUSIONS

Because both relationships are different from the identity line and using a single equation may not be appropriate to predict exercise intensity at the individual level, a rethinking of the relationships between the intensity variables may be necessary to ensure that the most suitable health-enhancing aerobic exercise intensity is prescribed.

Changes in Oxygen Consumption and Heart Rate After Acute Myocardial Infarction During 6-Month Follow-up

BACKGROUND

Exercise intensity is a particularly important determinant of physiological responses to exercise training in patients with acute myocardial infarction. Heart rate (HR) is commonly used as a practical way of prescribing and monitoring exercise as specific intensities based on a linear relationship between the percentage of maximum HR (%HR_max) and the percentage of maximum oxygen consumption (%VO_2max) regardless of age, gender, or exercise mode.

OBJECTIVE

To examine the change in variability in the correlation between %HR_max and %VO_2max after acute myocardial infarction.

DESIGN

Retrospective study.

SETTING

Regional cardio-cerebrovascular center at a tertiary hospital.

PATIENTS

A total of 66 patients were enrolled who were referred for cardiac rehabilitation (CR) after percutaneous intervention, and who had reached stage 3 of the modified Bruce Protocol (mBP) on an exercise tolerance test (ETT).

METHODS

There were 54 men and 12 women with an average age of 56.7 ± 9.48 years, ejection fraction (EF) of 56.4% ± 8.89%, and body mass index (BMI) of 24.73 ± 2.86 kg/m². All patients participated in a 4-week outpatient CR program and underwent ETT with a gas analyzer to determine maximal heart rate and maximal oxygen consumption before CR and 1 month, 3 months, and 6 months after CR.

MAIN OUTCOME MEASUREMENTS

VO_2max and HR_max were defined as the highest values attained during the ETT. The HR and VO₂ values at each stage of the mBP were expressed as percentages of their maximum. %HR_max and %VO_2max were calculated at each stage of the mBP.

RESULTS

The maximum METs and VO_2max significantly improved at 1 month after CR, but not significantly at 3 and 6 months after CR. The correlation between VO_2max and HR_max progressively changed in a favorable manner during CR. The relationship between %HR_max and %VO_2max indicated a coefficient of variation before and 1, 3, and 6 months after of 0.800, 0.826, 0.832, and 0.880, respectively.

CONCLUSIONS

This study showed that the %HR_max correlates better with the %VO_2max in the late-stage post-AMI than in the initial stage. We should therefore set and monitor the exercise intensity using maximal oxygen consumption in the early stage of exercise training after onset of acute myocardial infarction.

LEVEL OF EVIDENCE

IV.

Immersible ergocycle prescription as a function of relative exercise intensity

PURPOSE

The purpose of this study was to establish the relationship between various expressions of relative exercise intensity percentage of maximal oxygen uptake (%VO_2max), percentage of maximal heart rate (%HR_max), %VO₂ reserve (%VO₂R), and %HR reserve (%HRR)) in order to obtain the more appropriate method for exercise intensity prescription when using an immersible ergocycle (IE) and to propose a prediction equation to estimate oxygen consumption (VO₂) based on IE pedaling rate (rpm) for an individualized exercise training prescription.

METHODS

Thirty-three healthy participants performed incremental exercise tests on IE and dryland ergocycle (DE) at equal external power output (P_ext). Exercise on IE began at 40 rpm and was increased by 10 rpm until exhaustion. Exercise on DE began with an initial load of 25 W and increased by 25 W/min until exhaustion. VO₂ was measured with a portable gas analyzer (COSMED K4b²) during both incremental tests. On IE and DE, %VO₂R, %HR_max, and %HRR at equal P_ext did not differ (p > 0.05).

RESULTS

The %HRR vs. %VO₂R regression for both IE and DE did not differ from the identity line %VO₂R IE = 0.99 × HRR IE (%) + 0.01 (r ² = 0.91, SEE = 11%); %VO₂R DE = 0.94 × HRR DE (%) + 0.01 (r ² = 0.94, SEE = 8%). Similar mean values for %HR_max, %VO₂R, and %HRR at equal P_ext were observed on IE and DE. Predicted VO₂ obtained according to rpm on IE is represented by: VO₂ (L/min) = 0.000542 × rpm² - 0.026 × rpm + 0.739 (r = 0.91, SEE = 0.319 L/min).

CONCLUSION

The %HRR-%VO₂R relationship appears to be the most accurate for exercise training prescription on IE. This study offers new tools to better prescribe, control, and individualize exercise intensity on IE.

Exercise intensity classification in cancer patients undergoing allogeneic HCT

OBJECTIVE

Exercise intervention studies during and after cancer treatment show beneficial effects for various physical and psychosocial outcomes. Current exercise intensity guidelines for cancer patients are rather general and have been adapted from American College of Sports Medicine (ACSM) recommendations for healthy individuals. Intensive cancer treatment regimens such as allogeneic hematopoietic stem cell transplantation (allo-HCT) may change the cardiovascular response to acute exercise. Therefore, we evaluated the relationships between %V˙O2 reserve (%V˙O2R, reference) and %HRR, %HRmax, and %V˙O2max and compared calculated intensities with given intensities by ACSM.

METHODS

Measurements before and 180 d after allo-HCT from a randomized controlled trial were used. Only patients who reached maximal effort and at least two exercise stages in our maximal incremental cycling test were included. Before allo-HCT, 106 patients were included, and 180 d after treatment, 49 patients met our inclusion criteria. Individual regression lines were calculated with V˙O2R as the reference. Calculated exercise intensities for endurance training prescription were compared with ACSM values.

RESULTS

Before allo-HCT, %HRR values of patients were significantly lower than ACSM values, and %HRmax and %V˙O2max values were significantly higher (except 90% HRmax, which was significantly lower, all P < 0.01). One hundred eighty days after allo-HCT, values for %HRR were not significantly different to ACSM values (except 90%, which was significantly lower, P = 0.01), whereas %HRmax and %V˙O2max were significantly higher (all P < 0.05). Furthermore, regression models revealed no influence of beta-blockers on calculated intensities.

CONCLUSIONS

ACSM's exercise intensity recommendations for endurance training may not be applicable for cancer patients during and 180 d after allo-HCT because they may not meet the targeted intensity class, with the exception of %HRR 180 d after allo-HCT.

The effects of high-intensity interval training on glucose regulation and insulin resistance: a meta-analysis

The aim of this meta-analysis was to quantify the effects of high-intensity interval training (HIIT) on markers of glucose regulation and insulin resistance compared with control conditions (CON) or continuous training (CT). Databases were searched for HIIT interventions based upon the inclusion criteria: training ≥2 weeks, adult participants and outcome measurements that included insulin resistance, fasting glucose, HbA1c or fasting insulin. Dual interventions and participants with type 1 diabetes were excluded. Fifty studies were included. There was a reduction in insulin resistance following HIIT compared with both CON and CT (HIIT vs. CON: standardized mean difference [SMD] = -0.49, confidence intervals [CIs] -0.87 to -0.12, P = 0.009; CT: SMD = -0.35, -0.68 to -0.02, P = 0.036). Compared with CON, HbA1c decreased by 0.19% (-0.36 to -0.03, P = 0.021) and body weight decreased by 1.3 kg (-1.9 to -0.7, P < 0.001). There were no statistically significant differences between groups in other outcomes overall. However, participants at risk of or with type 2 diabetes experienced reductions in fasting glucose (-0.92 mmol L(-1), -1.22 to -0.62, P < 0.001) compared with CON. HIIT appears effective at improving metabolic health, particularly in those at risk of or with type 2 diabetes. Larger randomized controlled trials of longer duration than those included in this meta-analysis are required to confirm these results.

Muscular strength, aerobic capacity, and adipocytokines in obese youth after resistance training: A pilot study

BACKGROUND

Exercise has shown positive training effects on obesity-related inflammation, however, resistance training has shown mixed results concerning adipocytokine levels.

AIMS

The purpose of this pilot study was to explore the effects of resistance training on blood adipocytokine concentrations in obese youth, with specific examination of the relationship between these biomarkers and improved fitness (i.e., aerobic capacity, muscular strength).

METHODS

Fourteen obese adolescents (16.1 ±1.6 y; BMI: 32.3 ±3.9 kg/m(2)) participated in a 16-week resistance training intervention. Body composition, fasting blood concentrations of interleukin-6 (IL-6), tumour necrosis factor-alpha (TNF-ɑ), adiponectin, and leptin were measured pre- and post-training. Aerobic capacity was assessed via a maximal discontinuous exercise test. The rate of gain in muscular strength was calculated as the slope of progression in 1-repetition maximum throughout the intervention.

RESULTS

Resistance training increased lean mass (total, trunk) and decreased per cent body fat (total, trunk). The training also caused moderate clear decreases in IL-6 and TNF-ɑ concentrations. A small increase in adiponectin was also observed before and after intervention. When the group was stratified by changes in aerobic capacity, there were substantially larger decreases in leptin levels for those with improved capacity. Correlation analyses also revealed a negative relationship between log-transformed leptin and aerobic capacity at rest. Improvement in quadriceps strength was positively correlated with IL-6 and TNF-ɑ, while improvement in shoulder adductor strength was positively correlated with IL-6 only.

CONCLUSION

Resistance training improved adipocytokine markers, which were partially associated with improved physical fitness. Specifically, the relationship between strength improvements and IL-6 and TNF-ɑ suggests an exercise-induced signalling pathway that results in overall adaptive decreases in systemic inflammation in obese youth.

Acute physiological responses to recreational in-line skating in young adults

We examined the physiological responses to in-line skating exercise at self-selected paces in recreationally trained adults. Seven men and 10 women performed in-line skating exercise during which oxygen uptake (VO2) and heart rate (HR) were recorded continuously. Ratings of perceived exertion (RPE) and blood lactate concentration were also obtained at the end of exercise. Furthermore, subjects' peak VO2, peak HR, RPE and gas-exchange thresholds were determined in laboratory settings. The average exercise intensity during in-line skating was 90% of peak HR, 67% of peak VO2, 84% of HR reserve and 64% of VO2 reserve. When expressed as RPE and as metabolic equivalents (METs), the average exercise intensity was 13.1 RPE and 9.4 METs. Overall, these indicators of exercise intensity categorise in-line skating at self-selected paces as a vigorous physical activity. Notably, at similar VO2 values, significantly higher HR (174 ± 16 vs. 156 ± 6 bpm; p<0.001) and RPE (13.1 ± 1.4 vs. 11.7 ± 1.4; p=0.019) were observed for in-line skating compared with treadmill running. We conclude that 1. recreational in-line skating induces physiological responses that are sufficient for improving and maintaining cardiovascular fitness in healthy adults, 2. HR- and RPE-based methods for quantifying the exercise intensity during in-line skating may overestimate the actual metabolic load and 3. the derivation of exercise prescriptions for in-line skating should be preferably based on specific (i.e. in-line skating) graded exhaustive exercise test.

Energetic Cost and Preferred Speed of Walking in Obese vs. Normal Weight Women

OBJECTIVE

We tested the hypotheses that walking is more expensive for obese women, and they prefer slower walking speeds that minimize the gross energy cost per distance despite a greater relative aerobic effort [percent of maximal oxygen uptake (Vo(2max))/kg].

RESEARCH METHODS AND PROCEDURES

Twenty adult women, 10 obese (BMI = 34.1 +/- 3.2 kg/m(2)) and 10 normal weight (BMI = 20.4 +/- 2.1 kg/m(2)) volunteered. To determine the metabolic rate and energy cost per distance vs. speed relationships, we measured Vo(2) and V(CO(2)) while subjects walked on a treadmill at six speeds (0.50, 0.75, 1.0, 1.25, 1.5, and 1.75 m/s; 5-minute trials, with a 5-minute rest period between trials). We measured preferred walking speed on a 50-m section of level sidewalk and Vo(2max) using a modified Balke treadmill protocol.

RESULTS

Walking was 11% more expensive for the obese subjects, but they preferred to walk at similar speeds as normal weight subjects (1.40 vs. 1.47 m/s, p = 0.07). Both groups preferred walking speeds at which their gross energy cost per distance was almost minimized. Obese subjects had a smaller Vo(2max)/kg, so they required a greater relative aerobic effort at the preferred speed (51% vs. 36%, p = 0.001).

DISCUSSION

Obese women preferred a walking speed that minimized energy cost per distance, even though this strategy required a greater relative aerobic effort than walking more slowly. Our results suggest that walking slower for a set distance may be an appropriate exercise recommendation for a weight management prescription in obese adults.

Do the speeds defined by the American College of Sports Medicine metabolic equation for running produce target energy expenditures during isocaloric exercise bouts?

The accuracy of the American College of Sports Medicine (ACSM) equations for producing predicted values of heart rate reserve (HRR) and oxygen uptake reserve (VO2R) and consequently, target energy expenditure (EE) during exercise are yet to be established. This study investigated whether speeds defined by the ACSM metabolic equation for running correctly estimate the EEs during isocaloric exercise bouts. Twenty-eight men performed a ramp-incremental maximal exercise test to determine HRmax and VO2max. Two continuous exercise bouts at 60 and 80% VO2R and target EE of 400 kcal were then performed. In the 60% VO2R exercise the observed VO2R and EE were lower than predicted only during the first time quartile of the bout (t = 6.5, p < 0.001), whereas at 80% VO2R it was lower during the first (t = 15.3, p < 0.001), second (t = 5.4, p < 0.001) and third (t = 3.1, p = 0.025) quartiles. The observed HR was lower than predicted in the first time quartile of the 60% [Formula: see text] (t = 5.6, p < 0.001) and 80% VO2R bouts (t = 10.7, p < 0.001), whereas no significant differences occurred for any other time quartiles (p ≥ 0.23). In conclusion, the running speed defined by the ACSM metabolic equation overestimated VO2R and EE within exercise performed at 60 and 80% VO2R especially in higher intensities.

American College of Sports Medicine position stand. Quantity and quality of exercise for developing and maintaining cardiorespiratory, musculoskeletal, and neuromotor fitness in apparently healthy adults: guidance for prescribing exercise

The purpose of this Position Stand is to provide guidance to professionals who counsel and prescribe individualized exercise to apparently healthy adults of all ages. These recommendations also may apply to adults with certain chronic diseases or disabilities, when appropriately evaluated and advised by a health professional. This document supersedes the 1998 American College of Sports Medicine (ACSM) Position Stand, "The Recommended Quantity and Quality of Exercise for Developing and Maintaining Cardiorespiratory and Muscular Fitness, and Flexibility in Healthy Adults." The scientific evidence demonstrating the beneficial effects of exercise is indisputable, and the benefits of exercise far outweigh the risks in most adults. A program of regular exercise that includes cardiorespiratory, resistance, flexibility, and neuromotor exercise training beyond activities of daily living to improve and maintain physical fitness and health is essential for most adults. The ACSM recommends that most adults engage in moderate-intensity cardiorespiratory exercise training for ≥30 min·d on ≥5 d·wk for a total of ≥150 min·wk, vigorous-intensity cardiorespiratory exercise training for ≥20 min·d on ≥3 d·wk (≥75 min·wk), or a combination of moderate- and vigorous-intensity exercise to achieve a total energy expenditure of ≥500-1000 MET·min·wk. On 2-3 d·wk, adults should also perform resistance exercises for each of the major muscle groups, and neuromotor exercise involving balance, agility, and coordination. Crucial to maintaining joint range of movement, completing a series of flexibility exercises for each the major muscle-tendon groups (a total of 60 s per exercise) on ≥2 d·wk is recommended. The exercise program should be modified according to an individual's habitual physical activity, physical function, health status, exercise responses, and stated goals. Adults who are unable or unwilling to meet the exercise targets outlined here still can benefit from engaging in amounts of exercise less than recommended. In addition to exercising regularly, there are health benefits in concurrently reducing total time engaged in sedentary pursuits and also by interspersing frequent, short bouts of standing and physical activity between periods of sedentary activity, even in physically active adults. Behaviorally based exercise interventions, the use of behavior change strategies, supervision by an experienced fitness instructor, and exercise that is pleasant and enjoyable can improve adoption and adherence to prescribed exercise programs. Educating adults about and screening for signs and symptoms of CHD and gradual progression of exercise intensity and volume may reduce the risks of exercise. Consultations with a medical professional and diagnostic exercise testing for CHD are useful when clinically indicated but are not recommended for universal screening to enhance the safety of exercise.

Maximal heart rate prediction in adults that are overweight or obese

An accurate predictor of maximal heart rate (MHR) is necessary to prescribe safe and effective exercise in those considered overweight and obese when actual measurement of MHR is unavailable or contraindicated. To date, accuracy of MHR prediction equations in individuals that are overweight or obese has not been well established. The purpose of this study was to examine the accuracy of 3 equations for predicting MHR in adults that are overweight or obese. One hundred seventy-three sedentary adults that were overweight or obese enrolled in weight-loss study and performed a VO₂peak treadmill test before the start of the weight loss treatment. A total of 132 of the 173 participants met conditions for achieving maximal exercise testing criteria and were included in this study. Maximal heart rate values determined from VO₂peak treadmill tests were compared across gender, age, and weight status with the following prediction equations: (a) 220 - age, (b) 208 - 0.7 × age, and (c) 200 - 0.48 × age. Among 20- to 40-year-old participants, actual MHR averaged 180 ± 9 b·min⁻¹ and was overestimated (p < 0.001) at 186 ± 5 b·min⁻¹ with the 220 - age equation. Weight status did not affect predictive accuracy of any of the 3 equations. For all participants, the equation, 200-0.48 × age estimated MHR to be 178 ± 4 b·min⁻¹, which was greater than the actual value (175 ± 12, p = 0.005). Prediction equations showed close agreement to actual MHR, with 208 - 0.7 × age being the most accurate.

The impact of obesity on physiological responses during prolonged exercise

BACKGROUND

Prolonged, moderate-intensity exercise training is routinely prescribed to subjects with obesity. In the general population, this type of exercise can lead to fluid and sodium imbalance. However, little is known whether obesity alters the risk of fluid and sodium imbalances.

OBJECTIVE

This study examined physiological responses, such as core body temperature, fluid and sodium balance, in lean (BMI<25), overweight (25<BMI<30) and obese (BMI>30) subjects during prolonged moderate-intensity exercise.

SUBJECTS

A total of 93 volunteers (24-80 years), stratified for BMI, participated in the Nijmegen Marches and walked 30-50 km at a self-selected pace. Heart rate and core body temperature were recorded every 5 km. Subjects reported fluid intake, while urine output was measured and sweat rate was calculated. Baseline and post-exercise plasma sodium levels were determined, and urinary specific gravity levels were assessed before and after exercise.

RESULTS

BMI groups did not differ in training status preceding the experiment. Exercise duration (8 h 41 ± 1 h 36 min) and intensity (72 ± 9% HR(max)) were comparable across groups, whereas obese subjects tended to have a higher maximum core body temperature than lean controls (P=0.06). Obese subjects demonstrated a significantly higher fluid intake (P<0.001) and sweat rate (P<0.001), but lower urine output (P<0.05) compared with lean subjects. In addition, higher urine specific gravity levels were observed in obese versus lean subjects after exercise (P<0.05). Furthermore, plasma-sodium concentration did not change in lean subjects after exercise, whereas plasma-sodium levels increased significantly (P<0.001) in overweight and obese subjects. Also, overweight and obese subjects demonstrated a significantly larger decrease in body mass after exercise than lean controls (P<0.05).

CONCLUSION

Obese subjects demonstrate a larger deviation in markers of fluid and sodium balance than their lean counterparts during prolonged moderate-intensity exercise. These findings suggest that overweight and obese subjects, especially under strenuous environmental conditions, have an increased risk to develop fluid and sodium imbalances.

Inaccuracy of the HR reserve vs. V˙O2 reserve relationship during prone arm-paddling exercise in surfboard riders

Previous studies have demonstrated that during lower-body exercise the percentage of heart rate reserve (%HRR) is equivalent to the percentage of the oxygen consumption reserve (%V˙O(2R)) but not to a percentage of the peak oxygen consumption (%V˙O(2peak)). The current study examined these relationships in trained surfboard riders (surfers) during upper-body exercise. Thirteen well-trained competitive surfers performed a stepwise, incremental, prone arm-paddling exercise test to exhaustion. For each subject, data obtained at the end of each stage (i.e., HR and V˙O(2) values) were expressed as a percentage of HRR, V˙O(2peak), and V˙O(2R) respectively and used to determine the individual %HRR-%V˙O(2peak) and %HRR-%V˙O(2R) relationships. Mean slope and intercept were calculated and compared with the line of identity (slope=1, intercept=0). The %HRR versus %V˙O(2R) regression mean slope (0.88±0.06) and intercept (20.82±4.57) were significantly different (p<0.05) from 1 and 0, respectively. Similarly, the regression of %HRR versus %V˙O(2peak) resulted in a line that differed in the slope (p<0.05) but not in the intercept (p=0.94) from the line of identity. Predicted values of %HRR were significantly higher (p<0.05) from indicated values of %V˙O(2R) for all the intensities ranging from 35% to 95% V˙O(2R). Unlike results found for lower-body exercise, a given %HRR during prone upper-body exercise was not equivalent to its corresponding %V˙O(2R). Thus, to ensure more targeted exercise intensity during arm-paddling exercise, individual HR-V˙O(2) equations should be used.

Lifestyle intervention improves microvascular reactivity and increases serum adiponectin in overweight hypertensive patients

BACKGROUND AND AIMS

Obesity and hypoadiponectinemia are often associated with high blood pressure. Moreover, microvascular dysfunction is reported to be an early event in patients with hypertension and may be involved in the pathogenesis of organ damage.

METHODS AND RESULTS

We investigated the impact of 8-week moderate-intensity aerobic training on adiponectin plasma levels and skin microvascular reactivity in 24 overweight sedentary patients (18 men, age 44+/-6 years, body mass index 28+/-3 kg/m(2)) with never-treated grade 1 essential hypertension. Twenty-four age- and sex-matched hypertensive patients, who were examined twice at 8-week intervals in the absence of exercise training, served as controls. Exercise training was followed by a significant reduction in waist circumference (from 97+/-9 to 95+/-9 cm, p<0.05) and an increase in adiponectin plasma levels (from 11.9+/-3 to 12.5+/-4 mg/L, p<0.05). An inverse correlation was found between adiponectin change and waist circumference change (r=-0.43, p<0.05). The area under the curve after post-occlusive reactive hyperemia at skin laser-Doppler examination increased significantly after aerobic training (from 876+/-539 to 1468+/-925 PU/s, p<0.001). A positive correlation was found between exercise-induced variations of post-occlusive reactive hyperemia and adiponectin plasma levels (r=0.41, p<0.05). Office or 24-h blood pressure values did not change significantly.

CONCLUSION

In sedentary overweight patients with mild hypertension, moderate aerobic training improves cutaneous microvascular reactivity and adiponectin plasma levels. These changes precede blood pressure reduction and may serve as biomarkers of the efficacy of non-drug treatment in hypertensive patients.

Standards for the use of cardiopulmonary exercise testing for the functional evaluation of cardiac patients: a report from the Exercise Physiology Section of the European Association for Cardiovascular Prevention and Rehabilitation

Cardiopulmonary exercise testing (CPET) is a methodology that has profoundly affected the approach to patients' functional evaluation, linking performance and physiological parameters to the underlying metabolic substratum and providing highly reproducible exercise capacity descriptors. This study provides professionals with an up-to-date review of the rationale sustaining the use of CPET for functional evaluation of cardiac patients in both the clinical and research settings, describing parameters obtainable either from ramp incremental or step constant-power CPET and illustrating the wealth of information obtainable through an experienced use of this powerful tool. The choice of parameters to be measured will depend on the specific goals of functional evaluation in the individual patient, namely, exercise tolerance assessment, training prescription, treatment efficacy evaluation, and/or investigation of exercise-induced adaptations of the oxygen transport/utilization system. The full potentialities of CPET in the clinical and research setting still remain largely underused and strong efforts are recommended to promote a more widespread use of CPET in the functional evaluation of cardiac patients.

Impact of resistance training with or without caloric restriction on physical capacity in obese older women

OBJECTIVE

To investigate the specific impact of resistance training (RT) with or without caloric restriction (CR) on physical capacity in obese older women.

DESIGN

Forty-eight postmenopausal obese women, physically independent and between the ages of 55 and 75 years were recruited. The women were randomly assigned to one of four groups (1: RT [n = 12], 2: CR [n = 12], 3: CR + RT [n = 12], or 4: control group [C; n = 12]) for 3 months. CR and CR + RT groups participated in a weekly group session on nutrition, and RT and CR + RT groups took part in a resistance training program. Physical capacity was measured with 11 different performance tests. A global physical capacity score (range, 0-44) was then computed using quartiles of each test. Body composition was measured by dual-energy x-ray absorptiometry.

RESULTS

Body weight, total fat mass, percentage of fat mass, and body mass index (kg/m) significantly decreased in the CR and CR + RT groups (P < 0.01), whereas only the CR group showed a significant decrease in lean body mass (P < 0.05) after the 3-month program. The global physical capacity score significantly improved in the RT group (10.0 +/- 8.8%; P < 0.01), compared with the C group after 3 months.

CONCLUSION

Overall, the 3-month RT program alone had a greater effect on physical capacity than CR or CR + RT. Thus, a 3-month RT could help prevent long-term decreases in physical capacity in obese older women.

Exercise intensity prescription in obese individuals

The main purpose of this study was to evaluate the relationship between different methods proposed by the American College of Sports Medicine (ACSM) to prescribe exercise intensity using heart rate (HR) and oxygen uptake (VO2) in obese individuals. Sixty-eight overweight to severely obese adults were divided into three groups (tertile) based on their BMI. The groups were T1 group (BMI = 30.5 +/- 1.5, n = 23), T2 group (BMI = 34.3 +/- 1.0, n = 23), and T3 group (BMI = 40.2 +/- 3.7, n = 22). All subjects performed a graded exercise test using a ramp protocol on a treadmill. Individual linear regressions between %HR reserve (%HRR) and %VO2 reserve (%VO2R), %HRR and %VO2 peak (%VO2peak), %maximal HR (%HRmax) and %VO2R, and %HRmax and %VO2peak were calculated. When all the subjects were grouped together, the %HRR-%VO2R mean regression was partially related to the line of identity, while the %HRR-%VO2peak, %HRmax-%VO2R, and %HRmax-%VO2peak mean regressions were all significantly different than the line of identity (P < 0.001). The degree of obesity accounted for approximately 15% of the variation for both %HRR-%VO2R and %HRR-%VO2peak mean regressions. The %HRmax-%VO2R and %HRmax-%VO2peak mean regressions were not affected by the degree of obesity but resting HR accounted for 28-37% of the variation. The relationship between the exercise intensity determined by the %HRR-%VO2R and the %HRR-%VO2peak mean regression seems to be influenced by the degree of obesity. The degree of obesity does not affect the relationship between exercise intensity generated by the %HRmax-%VO2R or %HRmax-%VO2peak equations but the resting HR does.

Relationship between %HRmax, %HR Reserve, %V˙O2max, and %V˙O2 Reserve in Elite Cyclists

PURPOSE

To evaluate the relations between %HRmax, %HRR, %VO2max, and %VO2R in elite cyclists and to check whether the intensity scale recommended by ACSM in its 1998 position stand is also applicable to this specific population.

METHODS

Twenty-six male elite road cyclists (25.1 +/- 0.7 yr, 71.0 +/- 1.2 kg, 70.9 +/- 1.2 mL x kg(-1) x min(-1), 433.9 +/- 9.8 W) performed an incremental maximal exercise test (50 W x 3 min(-1)). Individual linear regressions based on HR and VO2 values measured at rest, end of each stage, and maximum, were used to calculate slopes and intercepts, and to predict %HRmax, %HRR, %VO2max, or %VO2R for a given exercise intensity.

RESULTS

Below 85% VO2max or VO2R, predicted %HRmax values were significantly higher (P < 0.001) than the ACSM intensity scale (58, 65, 73, and 87% vs 55, 62, 70, and 85% HRmax at 40, 50, 60, and 80% VO2max, and 48, 61, 74% vs 35, 55, and 70% HRmax at 20, 40, and 60% VO2R). The %HRR versus %VO2max regression mean slope (1.069 +/- 0.01) and intercept (-5.747 +/- 0.80) were significantly different (P < 0.0001) from 1 and 0, respectively. Conversely, the %HRR versus %VO2R regression was indistinguishable from the line of identity (mean slope = 1.003 +/- 0.01; mean intercept = 0.756 +/- 0.7). Predicted %VO2R values were equivalent to %HRR in the 35-95%HRR range. %VO2max was equivalent to %HRR at and above 75%HRR, and it was significantly higher at (P < 0.05) and below 65%HRR (P < 0.001).

CONCLUSION

The intensity scale recommended by ACSM underestimates exercise intensity in elite cyclists. Prediction of %HRR by %VO2R is better than by %VO2max. Thus, elite cyclists should use %HRR in relation to %VO2R rather than in relation to %VO2max.

Energy expenditure and physical activity in clozapine use: implications for weight management

OBJECTIVE

The management of atypical antipsychotic-induced weight gain is a significant challenge for people with mental illness. Fundamental research into energy metabolism in people taking atypical antipsychotic medication has been neglected. The current study of men with schizophrenia taking clozapine aimed to measure total energy expenditure (TEE) and energy expended on physical activity--activity energy expenditure (AEE) and to consider the clinical implications of the findings.

METHOD

The well-established reference method of doubly labelled water (DLW) was used to measure TEE and AEE in men with schizophrenia who had been taking clozapine for more than 6 months. Resting energy expenditure was determined using indirect calorimetry.

RESULTS

The TEE was 2511+/-606 kcal day-1 which was significantly different to World Health Organization recommendations (more than 20% lower). The Physical activity level (PAL) was 1.39+/-0.27 confirming the sedentary nature of people with schizophrenia who take clozapine.

CONCLUSIONS

The findings support the need for weight management strategies for people with schizophrenia who take clozapine to focus on the enhancement of energy expenditure by increasing physical activity and reducing inactivity or sedentary behaviours, rather than relying primarily on strategies to reduce energy intake.

Cardiorespiratory Fitness and Short-term Complications After Bariatric Surgery

BACKGROUND

Morbid obesity is associated with reduced functional capacity, multiple comorbidities, and higher overall mortality. The relationship between complications after bariatric surgery and preoperative cardiorespiratory fitness has not been previously studied.

METHODS

We evaluated cardiorespiratory fitness in 109 patients with morbid obesity prior to laparoscopic Roux-en-Y gastric bypass surgery. Charts were abstracted using a case report form by reviewers blinded to the cardiorespiratory evaluation results.

RESULTS

The mean age (+/- SD) was 46.0 +/- 10.4 years, and 82 patients (75.2%) were female. The mean body mass index (BMI) was 48.7 +/- 7.2 (range, 36.0 to 90.0 kg/m(2)). The composite complication rate, defined as death, unstable angina, myocardial infarction, venous thromboembolism, renal failure, or stroke, occurred in 6 of 37 patients (16.6%) and 2 of 72 patients (2.8%) with peak oxygen consumption (Vo(2)) levels < 15.8 mL/kg/min or > 15.8 mL/kg/min (lowest tertile), respectively (p = 0.02). Hospital lengths of stay and 30-day readmission rates were highest in the lowest tertile of peak Vo(2) (p = 0.005). There were no complications in those with BMI < 45 kg/m(2) or peak Vo(2) > or= 15.8 mL/kg/min. Multivariate analysis adjusting for age and gender found peak Vo(2) was a significant predictor of complications: odds ratio, 1.61 (per unit decrease); 95% confidence interval, 1.19 to 2.18 (p = 0.002).

CONCLUSIONS

Reduced cardiorespiratory fitness levels were associated with increased, short-term complications after bariatric surgery. Cardiorespiratory fitness should be optimized prior to bariatric surgery to potentially reduce postoperative complications.

Validity and Reliability of the North Carolina 6-Minute Cycle Test

PURPOSE

The purposes of this investigation were to determine (1) if the 6-minute cycle (6MC) test is a valid and reliable measure of physical performance in cardiac patients and (2) if physiologic responses to the 6-minute walk (6MW) and 6MC tests differ in men and women.

METHODS

Subjects were 101 phase II cardiac rehabilitation patients aged 40 to 79 years. Each subject performed a maximal graded exercise test (MGXT), a 6MW test, and three 6MC tests on separate days.

RESULTS

Pearson product moment correlation r values ranged from 0.78 to 0.89 (P = .001) when the three 6MC tests were compared with one another, indicating good test/retest reliability. The 6MC tests were all significantly and positively correlated to 6MW distance (P < .01), with r values ranging from 0.55 to 0.59. Each 6MC test was also correlated with maximal graded exercise test total time (P < .01), with r values ranging from 0.51 to 0.63, and with estimated maximal metabolic equivalents (P < .01), with r values ranging from 0.44 to 0.60. Although heart rate, systolic blood pressure, rate-pressure product, and rating of perceived exertion values for men were greater during the 6MC test than during the 6MW test (P < .001), no differences were seen in these parameters between tests in women (P = .166 to.260), with the exception of a greater exercise rating of perceived exertion seen during the 6MC test(P = .009).

CONCLUSION

The North Carolina 6MC test seems to provide a valid and reliable measure of functional abilities in phase II cardiac rehabilitation participants. Men generally present with greater heart rate, systolic blood pressure, and rate-pressure product values during this test than do the women when compared with a standard 6MW test.

A simple tool to predict exercise capacity of obese patients with ischaemic heart disease

OBJECTIVE

To define an equation that predicts exercise capacity taking into account body mass index (BMI).

DESIGN

Retrospective analysis and validation study of a multidisciplinary programme aimed at weight loss and physical rehabilitation.

SETTING

Tertiary referral hospital.

PATIENTS AND METHODS

372 consecutive obese participants (249 men) with stable ischaemic heart disease, aged mean 60.1 (SD 8.7) years, underwent a treadmill exercise test. BMI was 37.8 (4.5) kg/m(2). In the validation study the model was tested in 87 patients with similar characteristics.

RESULTS

Mean exercise intensity was 6.6 (SD 2.4) metabolic equivalents (METs). Multivariate linear regression analysis defined two simple models that considered exercise intensity as the dependent variable and a set of independent variables such as anthropometric measures, age and sex in the first one, plus associated clinical conditions and drug treatment in the second one. The correlation coefficients of the two models were R = 0.630 and R = 0.677, respectively. Age, BMI and sex were the strongest predictors of exercise capacity. The first derived equation efficiently predicted exercise capacity: in the validation study predicted exercise intensity was 6.3 (1.6) METs and attained exercise intensity was 6.3 (2.4) METs (p = 0.903) with a highly significant correlation (R = 0.534, p < 0.001).

CONCLUSION

BMI is an important determinant of exercise capacity of obese people with ischaemic heart disease. The use of a simple equation may help in predicting exercise capacity, in individualising exercise protocol and in setting up rehabilitation programs for obese patients.

Differences in eating and activity markers among normal weight, overweight, and obese rural women

PURPOSE

The purpose of this study was to examine differences in healthy eating and physical activity behaviors and associated biomarkers among normal weight (body mass index [BMI] < 25), overweight (BMI 25-29.9), and obese (BMI > or = 30) rural women.

METHODS

Random digit dialing was used to recruit 225 rural women (57.9 +/- 5.6 years). Measures of healthy eating and physical activity were completed on the computer during individual sessions at the rural sites. Research nurses then assessed a battery of biomarkers of activity and eating, including blood lipids, blood pressure, cardiorespiratory fitness (VO(2max)), and resting heart rate.

RESULTS

Major findings were differences across weight categories in daily calories consumed and expended, daily fruit servings, daily meat group servings, high-density lipoprotein cholesterol, vital signs, and cardiorespiratory fitness. The obese women both consumed and expended significantly more calories daily than those in the other two weight groups. Obese women consumed significantly fewer fruit group servings than both the normal weight and overweight women. Obese women consumed significantly more meat group servings than overweight women. There also were significant differences in systolic blood pressure, diastolic blood pressure, resting heart rate, high-density lipoprotein cholesterol, and cardiorespiratory fitness across the three weight groups.

CONCLUSIONS

This study provides evidence of major differences in some eating and activity behaviors and biomarkers across BMI groups. Major differences exist between the normal weight and overweight group as compared to the obese group.

Is the intensity of the highest fat oxidation at the lactate concentration of 2 mmol L(-1)? A comparison of two different exercise protocols

BACKGROUND

The exercise intensity eliciting highest fat oxidation is important for a variety of populations and its precise determination requires an adequate exercise protocol. The aim of this study was to compare fat oxidation, concentration of lactate and lactate threshold during an established exercise protocol using fixed workloads with a protocol based upon the subject's individual heart rate response to exercise.

MATERIALS AND METHODS

Highest fat oxidation, concentration of lactate and lactate threshold were compared between two different exercise protocols in moderately trained men (n = 48) and women (n = 30). In randomized order subjects completed a standardized (STAND) and an individual (IND) submaximal exercise test. The increments during IND were adapted by the subjects' individual heart rate response to exercise compared to STAND with defined steps.

RESULTS

In men, fat oxidation was significantly higher at the intensity eliciting highest fat oxidation in STAND than in IND (P = 0.019), but not in women. In both genders lactate concentration (P < 0.001) and heart rate (HR) (P < 0.001) were significantly higher in IND compared to STAND at this intensity. A significant correlation between O2 at lactate threshold and the intensity eliciting the highest fat oxidation was found in both genders in IND (women r = 0.73; men r = 0.43) and in STAND (women r = 0.57; men r = 0.56).

CONCLUSION

Different exercise increments and stage durations have an influence on lactate concentration and HR at the intensity eliciting the highest fat oxidation. The shorter test duration of STAND favours this protocol to determine maximal fat oxidation. For the untrained, start of exercise should be at very low intensity.

Resting energy expenditure is lower than predicted in people taking atypical antipsychotic medication

Resting energy expenditure (REE) is lower than predicted in persons taking atypical antipsychotic medication, and weight management is a significant clinical challenge for some of them. However, to date there have been no published guidelines to assist clinicians in choosing appropriate prediction equations to estimate energy expenditure in persons taking atypical antipsychotic medications. The objectives of this study were to measure REE in a group of men taking the atypical antipsychotic clozapine and to determine whether REE can be accurately predicted for this population using previously published regression equations. REE was measured using indirect calorimetry via a ventilated hood on eight men who had completed at least 6 months of treatment with clozapine. Comparisons between measured REE and predicted REE using five different equations were undertaken. The commonly-used Harris-Benedict and Schofield equations systematically overestimated REE. Predictions of REE from other equations were too variable for clinical use. When estimating energy requirements as part of a weight-management program in men who have been taking clozapine for 6 months, predictions of REE from the equations of Harris-Benedict and Schofield should be reduced by 280 kcal/day.