Effects of Exercise Training Amount and Intensity on Peak Oxygen Consumption in Middle-Age Men and Women at Risk for Cardiovascular Disease

The Impact of the Physical Activity Level on Sarcopenic Obesity in Community-Dwelling Older Adults

Previous studies have reported that low levels of physical activity result in sarcopenic obesity (SO). However, the effects of specific intensities of physical activity on SO and the optimal amount of physical activity for lowering the prevalence of SO have not been well studied. This study aimed to identify the effects of physical activity levels and intensity on SO and the optimal amount of physical activity related to a lower prevalence of SO. This cross-sectional study used data from the nationwide Korean Frailty and Aging Cohort Study (KFACS), which included 2071 older adults (1030 men, 1041 women). SO was defined according to the criteria of the European Society for Clinical Nutrition Metabolism (ESPEN) and the European Association for the Study of Obesity (EASO). Multivariate logistic regression analysis was performed to investigate the association between the physical activity level and SO. The high activity group had a significantly lower prevalence of SO than the non-high activity (low and moderate activity) group. On the other hand, moderate-intensity physical activity was associated with a lower prevalence of SO. A total physical activity energy expenditure of > 3032 kcal/week (433 kcal/day) for men and 2730 kcal/week (390 kcal/day) for women was associated with a reduced prevalence of SO. The high physical activity and total physical energy expenditure described above may be beneficial for reducing the prevalence of SO.

Classifying Intensity Domains From Arm Cycle Ergometry Differs Versus Leg Cycling Ergometry

ABSTRACT

Astorino, TA, Robson, T, and McMillan, DW. Classifying intensity domains from arm cycle ergometry differs versus leg cycling ergometry. J Strength Cond Res 37(11): 2192-2199, 2023-This study compared the distribution of exercise intensity domains in response to progressive leg cycle ergometry (LCE) and arm cycle ergometry (ACE). Seventeen active men and women (age and body fat = 26 ± 7 years and 18 ± 3%) initially performed graded exercise on each modality to assess maximal oxygen uptake (V̇o2max) and peak power output (PPO). Using a randomized crossover design, they subsequently performed moderate intensity continuous exercise consisting of three 15-minute bouts at 20, 40, and 60% PPO on each modality. Gas exchange data (V̇o2, V̇co2, and VE), respiratory exchange ratio, heart rate (HR), blood lactate concentration (BLa), and perceptual responses were acquired. Only 2 subjects were classified in the same intensity domains across modalities, with LCE eliciting more subjects exercising at "vigorous" and "near-maximal" intensities than ACE. Time spent above 70 (22 ± 7 vs. 15 ± 8 minutes, d = 1.03) and 80 %HRmax (15 ± 6 vs. 9 ± 6 minutes, d = 1.04) was significantly greater with LCE vs. ACE. Compared with ACE, LCE revealed significantly higher (p < 0.05) peak (94 ± 6 vs. 88 ± 9 %HRmax, d = 0.81) and mean HR (73 ± 6 vs. 66 ± 6 %HRmax, d = 1.20), V̇o2 (54 ± 5 vs. 50 ± 7 %V̇o2max, d = 0.68), and BLa (5.5 ± 2.0 vs. 4.7 ± 1.5 mM, d = 0.48). The results exhibit that progressive leg cycling at identical intensities elicits a greater cardiometabolic stimulus than ACE.

Examining the Dose-Response Relationship between Physical Activity and Health Outcomes

Physical Activity and Health and LongevityPhysical activity is a powerful tool to improve health. This article reviews the evidence supporting a relationship between physical activity and health outcomes, including mortality, and discusses the optimal dose of physical activity.

The Effect of Endurance Training on Pulmonary V˙O2 Kinetics in Solid Organs Transplanted Recipients

Background: We investigated the effects of single (SL-ET) and double leg (DL-ET) high-intensity interval training on O2 deficit (O2Def) and mean response time (MRT) during square-wave moderate-intensity exercise (DL-MOD), and on the amplitude of V˙O2p slow component (SCamp), during heavy intensity exercise (DL-HVY), on 33 patients (heart transplant = 13, kidney transplanted = 11 and liver transplanted = 9). Methods: Patients performed DL incremental step exercise to exhaustion, two DL-MOD tests, and a DL-HVY trial before and after 24 sessions of SL-ET (n = 17) or DL-ET (n = 16). Results: After SL-ET, O2Def, MRT and SCamp decreased by 16.4% ± 13.7 (p = 0.008), by 15.6% ± 13.7 (p = 0.004) and by 35% ± 31 (p = 0.002), respectively. After DL-ET, they dropped by 24.9% ± 16.2 (p < 0.0001), by 25.9% ± 13.6 (p < 0.0001) and by 38% ± 52 (p = 0.0003), respectively. The magnitude of improvement of O2Def, MRT, and SCamp was not significantly different between SL-ET and DL-ET after training. Conclusions: We conclude that SL-ET is as effective as DL-ET if we aim to improve V˙O2p kinetics in transplanted patients and suggest that the slower, V˙O2p kinetics is mainly caused by the impairment of peripherals exchanges likely due to the immunosuppressive medications and disuse.

Interindividual Differences in Trainability and Moderators of Cardiorespiratory Fitness, Waist Circumference, and Body Mass Responses: A Large-Scale Individual Participant Data Meta-analysis

Although many studies have assumed variability reflects variance caused by exercise training, few studies have examined whether interindividual differences in trainability are present following exercise training. The present individual participant data (IPD) meta-analysis sought to: (1) investigate the presence of interindividual differences in trainability for cardiorespiratory fitness (CRF), waist circumference, and body mass; and (2) examine the influence of exercise training and potential moderators on the probability that an individual will experience clinically important differences. The IPD meta-analysis combined data from 1879 participants from eight previously published randomized controlled trials. We implemented a Bayesian framework to: (1) test the hypothesis of interindividual differences in trainability by comparing variability in change scores between exercise and control using Bayes factors; and (2) compare posterior predictions of control and exercise across a range of moderators (baseline body mass index (BMI) and exercise duration, intensity, amount, mode, and adherence) to estimate the proportions of participants expected to exceed minimum clinically important differences (MCIDs) for all three outcomes. Bayes factors demonstrated a lack of evidence supporting a high degree of variance attributable to interindividual differences in trainability across all three outcomes. These findings indicate that interindividual variability in observed changes are likely due to measurement error and external behavioural factors, not interindividual differences in trainability. Additionally, we found that a larger proportion of exercise participants were expected to exceed MCIDs compared with controls for all three outcomes. Moderator analyses identified that larger proportions were associated with a range of factors consistent with standard exercise theory and were driven by mean changes. Practitioners should prescribe exercise interventions known to elicit large mean changes to increase the probability that individuals will experience beneficial changes in CRF, waist circumference and body mass.

Objectively Assessed Cardiorespiratory Fitness and All-Cause Mortality Risk: An Updated Meta-analysis of 37 Cohort Studies Involving 2,258,029 Participants

OBJECTIVE

To detail the magnitude and specificity of the association between cardiorespiratory fitness (CRF) and all-cause mortality risk.

METHODS

Cohort studies with at least 1 year of follow-up were sought from inception until December 2021 in MEDLINE, Embase, Web of Science, and a manual search of relevant articles. Relative risks (RRs) with 95% CIs were pooled using random-effects models. Quality of the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation tool.

RESULTS

A total of 37 unique studies comprising of 2,258,029 participants with 108,613 all-cause mortality events were eligible. The pooled multivariable-adjusted RR for all-cause mortality comparing the top vs bottom tertiles of CRF levels was 0.55 (95% CI, 0.50 to 0.61). When CRF was expressed in metabolic equivalent task (MET) units, the corresponding pooled RR was 0.56 (95% CI, 0.50 to 0.62). For every 1-MET increase in CRF, the RR for all-cause mortality was 0.89 (95% CI, 0.86 to 0.92). Strength of the association did not differ by publication year, age, sex, follow-up duration, CRF assessment method, or risk of bias.

CONCLUSION

Aggregate analysis of observational cohort studies confirms a strong inverse and independent association between CRF and all-cause mortality risk. The results suggest that guideline bodies should consider the inclusion of CRF in standard risk panels for mortality risk assessment.

[Molecular mechanisms of adaptive and therapeutic effects of physical activity in patients with cardiovascular diseases]

Physical activity is one of the main components of the rehabilitation of patients with cardiovascular disease (CVD). As shown by practice and the results of evidence-based studies, the beneficial effects of physical activity on disease outcomes in a number of cardiac nosologies are comparable to drug treatment. This gives the doctor another tool to influence the unfavorable epidemiological situation in developed countries with the spread of diseases of the cardiovascular system and CVD mortality. Reliable positive results of cardiorehabilitation (CR) were obtained using various methods. The goal of CR is to restore the optimal physiological, psychological and professional status, reduce the risk of CVD and mortality. In most current CVD guidelines worldwide, cardiac rehabilitation is a Class I recommendation. The molecular mechanisms described in the review, initiated by physical activity, underlie the multifactorial effect of the latter on the function of the cardiovascular system and the course of cardiac diseases. Physical exercise is an important component of the therapeutic management of patients with CVD, which is supported by the results of a meta-analysis of 63 studies associated with various forms of aerobic exercise of varying intensity (from 50 to 95% VO₂) for 1 to 47 months, which showed that CR based on physical exercise improves cardiorespiratory endurance. Knowledge of the molecular basis of the influence of physical activity makes it possible to use biochemical markers to assess the effectiveness of rehabilitation programs.

Exercise Training Intensity and the Fitness-Fatness Index in Adults with Metabolic Syndrome: A Randomized Trial

Background

Cardiorespiratory fitness and fatness (notably central obesity) are mediating factors of the metabolic syndrome (MetS) and consequent cardiovascular disease (CVD)/mortality risk. The fitness-fatness index (FFI) combines these factors and has been reported to be a better indicator of CVD and all-cause mortality risk, beyond the capacity of either fitness or fatness alone.

Objective

This study sought to investigate the effects of different exercise intensities on FFI in adults with MetS.

Methods

This was a sub-study of the ‘Exercise in the prevention of Metabolic Syndrome’ (EX-MET) multicentre trial. Ninety-nine adults diagnosed with MetS according to the International Diabetes Federation criteria were randomized to one of the following 16-week exercise interventions: i) moderate-intensity continuous training (MICT) at 60–70% HRpeak for 30 min/session (n = 34, 150 min/week); ii) 4 × 4 min bouts of high-intensity interval training at 85–95% HRpeak, interspersed with 3-min active recovery at 50–70% HRpeak (n = 34, 38 min/session, 114 min/week); and iii) 1 × 4 min bout of HIIT at 85–95% HRpeak (n = 31, 17 min/session, 51 min/week). Cardiorespiratory fitness (peak oxygen uptake, V̇O2peak) was determined via indirect calorimetry during maximal exercise testing and fatness was the ratio of waist circumference-to-height (WtHR). FFI was calculated as V̇O2peak in metabolic equivalents (METs) divided by WtHR. A clinically meaningful response to the exercise intervention was taken as a 1 FFI unit increase.

Results

Seventy-seven participants completed pre and post testing to determine FFI. While there was no significant between group difference (p = 0.30), there was a small group x time interaction effect on FFI [F(2, 73) = 1.226; η2 = 0.01], with numerically greater improvements following HIIT (4HIIT, + 16%; 1HIIT, + 11%) relative to MICT (+ 7%). There was a greater proportion of participants who had a clinically meaningful change in FFI following high-volume HIIT (60%, 15/25) and low-volume HIIT (65%, 17/26) compared to MICT (38%, 10/26), but with no significant between-group difference (p = 0.12). A similar trend was found when a sub-analysis comparing the FFI between those with type 2 diabetes (MICT, 33%, 3/9; high-volume HIIT, 64%, 7/11; and low-volume HIIT, 58%, 7/12) and without type 2 diabetes (MICT, 41%, 7/17; high-volume HIIT, 57%, 8/14; low-volume HIIT, 71%, 10/14).

Conclusion

Although there were no statistically significant differences detected between groups, this study suggests that the response to changes in FFI in adults with MetS may be affected by exercise intensity, when numerical differences between exercise groups are considered. Further research is warranted.

Trial registration number and date of registration: ClinicalTrials.gov NCT01676870; 31/08/2012.

Effects of Exercise Structure and Modality on Physiological and Perceptual Responses to Exercise

ABSTRACT

Bogdanis, GC, Mallios, VJ, Katsikas, C, Fouseki, T, Holman, I, Smith, C, and Astorino, TA. Effects of exercise structure and modality on physiological and perceptual responses to exercise. J Strength Cond Res 35(9): 2427-2432, 2021-This study examined the effect of exercise mode and intensity on physiological and perceptual responses to exercise. Twelve active adults (6 men and 6 women, age = 21.7 ± 1.6 years) initially performed incremental testing on the treadmill (TM) and cycle ergometer (CE) to assess maximal oxygen uptake (V̇o2max) and ventilatory threshold (VT). During the next 4 visits in a randomized order, subjects performed 20 minutes of moderate-intensity continuous exercise (MICE) at an intensity 20% below VT on the TM (TMMICE) and cycle ergometer (CEMICE) as well as time-matched high-intensity interval exercise (HIIE; 10 1-minute bouts at workload equal to 20% above VT followed by 1-minute active recovery) on both modes (TMHIIE and CEHIIE). During exercise, gas exchange data, blood lactate concentration, and perceptual responses (rating of perceived exertion, affective valence, and enjoyment) were assessed. Heart rate (p < 0.001) and V̇o2 (p < 0.001) were higher in response to TMHIIE vs. CEHIIE as well as TMMICE vs. CEMICE. Blood lactate concentration was higher (p = 0.003) in response to CEHIIE vs. TMHIIE. The rating of perceived exertion was significantly higher (p < 0.001) in TMMICE compared with CEMICE which showed the most positive affective valence (p = 0.009). Enjoyment was similar across all bouts (p = 0.11). Treadmill-based HIIE leads to higher heart rate and V̇o2 vs. CEHIIE, although there was no difference in affective valence or enjoyment. Practitioners aiming to optimize the cardiorespiratory response to moderate or interval exercise in their clientele should recommend TM running rather than cycling.

Effect of different types of regular exercise on physical fitness in adults with overweight or obesity: Systematic review and meta-analyses

This systematic review examined the effect of exercise training interventions on physical fitness in adults with overweight or obesity and compared the effectiveness of different types of exercise training. Four electronic databases were searched. Articles were included if they described randomized controlled trials of exercise training interventions and their effect on maximal oxygen consumption or muscle strength in adults with overweight or obesity. Changes in outcome parameters were analyzed using random effects meta-analyses for different training types (aerobic, resistance, combined aerobic plus resistance, and high-intensity interval training). Eighty-eight articles satisfied the inclusion criteria of which 66 (3964 participants) could be included in the meta-analyses. All training types increased VO_2max (mean difference 3.82 ml/min/kg (95% CI 3.17, 4.48), P < 0.00001; I² = 48%). In direct comparisons, resistance training was less effective in improving VO_2max than aerobic training, HIIT was slightly more effective than aerobic training, and no difference between aerobic and combined aerobic plus resistance training was found. For muscle strength benefits, incorporation of resistance exercise in the training program is indicated. Exercise training increases VO_2max and muscle strength in adults with overweight or obesity. Differences between training types should be weighed with other needs and preferences when health professionals advise on exercise training to improve physical fitness.

The association of estimated cardiorespiratory fitness with COVID-19 incidence and mortality: A cohort study

Background

It has been suggested that cardiorespiratory fitness (CRF) may be used to identify those at greatest risk for severe COVID-19 illness. However, no study to date has examined the association between CRF and COVID-19. The objectives of this study were to determine whether CRF is independently associated with testing positive with or dying from COVID-19.

Methods

This is a prospective cohort study of 2,690 adults from the UK Biobank Study that were followed from March 16^th, 2020 to July 26^th, 2020. Participants who were tested for COVID-19 and had undergone CRF assessment were examined. CRF was estimated (eCRF) and categorized as low (<20^th percentile), moderate (20^th to 80^th percentile) and high (≥80^th percentile) within sex and ten-year age groups (e.g. 50–60 years). Participants were classified as having COVID-19 if they tested positive (primarily PCR tests) at an in-patient or out-patient setting as of July 26, 2020. Participants were classified as having died from COVID-19 if the primary or underlying cause of death was listed ICD-10 codes U071 or U072 by June 30^th, 2020. Adjusted risk ratios (aRR) and 95% confidence intervals (CI) were estimated and a forward model building approach used to identify covariates.

Findings

There was no significant association between eCRF and testing positive for COVID-19. Conversely, individuals with moderate (aRR = 0.43, 95% CI: 0.25, 0.75) and high fitness (aRR = 0.37, 95% CI: 0.16, 0.85) had a significantly lower risk of dying from COVID-19 than those with low fitness.

Conclusions

While eCRF was not significantly associated with testing positive for COVID-19, we observed a significant dose-response between having higher eCRF and a decreased risk of dying from COVID-19. This suggests that prior gains in CRF could be protective against dying from COVID-19 should someone develop the virus.

Cardiopulmonary Exercise Testing in the Coronavirus Disease - 2019 Era: Safety and Protocol Considerations

ABSTRACT

Cardiopulmonary exercise testing (CPX) is a valuable tool in both clinical practice and research settings. Therefore, it is advantageous for human performance laboratories to continue operating during the coronavirus disease 2019 (COVID-19) pandemic. All institutions should adhere to general COVID-19 guidelines provided by the Centers for Disease Control. Because of the testing environment, CPX laboratories must consider additional precautionary safety measures. This article provides recommendations for modifying the CPX protocol to ensure safety for all stakeholders during the pandemic. These modifications are universal across all populations, types of institutions and testing modalities. Preliminary measures include careful review of federal, local, and institutional mandates. The description outlines how to evaluate a testing environment and alter workflow. Guidelines are provided on what specific personal protective equipment should be acquired; as well as necessary actions before, during, and after the CPX test. These precautions will limit the possibility of both clients and staff from contracting or spreading the disease while maintaining testing volume in the laboratory.

Exploring Differences in Cardiorespiratory Fitness Response Rates Across Varying Doses of Exercise Training: A Retrospective Analysis of Eight Randomized Controlled Trials

OBJECTIVE

This study tested the hypothesis that greater mean changes in cardiorespiratory fitness (CRF), in either the absence or presence of reduced interindividual variability, explain larger CRF response rates following higher doses of exercise training.

METHODS

We retrospectively analyzed CRF data from eight randomized controlled trials (RCT; n = 1590 participants) that compared at least two doses of exercise training. CRF response rates were calculated as the proportion of participants with individual confidence intervals (CIs) placed around their observed response that lay above 0.5 metabolic equivalents (MET). CIs were calculated using no-exercise control group-derived typical errors and were placed around each individual's observed CRF response (post minus pre-training CRF). CRF response rates, mean changes, and interindividual variability were compared across exercise groups within each RCT.

RESULTS

Compared with lower doses, higher doses of exercise training yielded larger CRF response rates in eight comparisons. For most of these comparisons (7/8), the higher dose of exercise training had a larger mean change in CRF but similar interindividual variability. Exercise groups with similar CRF response rates also had similar mean changes.

CONCLUSION

Our findings demonstrate that larger CRF response rates following higher doses of exercise training are attributable to larger mean changes rather than reduced interindividual variability. Following a given dose of exercise training, the proportion of individuals expected to improve their CRF beyond 0.5 METs is unrelated to the heterogeneity of individual responses.

The Association of Sleep Apnea and Cardiorespiratory Fitness With Long-Term Major Cardiovascular Events

OBJECTIVE

To determine the risk of long-term major adverse cardiovascular events (MACE) when sleep-disordered breathing (SDB) and decreased cardiorespiratory fitness (CRF) co-occur.

METHODS

We included consecutive patients who underwent symptom-limited cardiopulmonary exercise tests between January 1, 2005, and January 1, 2010, followed by first-time diagnostic polysomnography within 6 months. Patients were stratified based on the presence of moderate-to-severe SDB (apnea/hypopnea index ≥15 per hour) and decreased CRF defined as <70% predicted peak oxygen consumption (VO₂). Long-term MACE was a composite outcome of myocardial infarction (MI), coronary artery bypass graft (CABG), percutaneous coronary intervention (PCI), stroke or transient ischemic attack (TIA), and death, assessed until May 21, 2018. Cox-proportional hazard models were adjusted for factors known to influence CRF and MACE.

RESULTS

Of 498 included patients (60±13 years, 28.1% female), 175 (35%) had MACE (MI=17, PCI=14, CABG=13, stroke=20, TIA=12, deaths=99) at a median follow-up of 8.7 years (interquartile range=6.5 to 10.3 years). After adjusting for age, sex, beta blockers, systemic hypertension, diabetes mellitus, coronary artery disease, cardiac arrhythmia, chronic obstructive pulmonary disease, smoking, and use of positive airway pressure (PAP), decreased CRF alone (hazard ratio [HR]=1.91, 95% confidence interval [CI], 1.15 to 3.18; P=.01), but not SDB alone (HR=1.26, 95% CI, 0.75 to 2.13, P=.39) was associated with increased risk of MACE. Those with SDB and decreased CRF had greater risk of MACE compared with patients with decreased CRF alone (HR=1.85; 95% CI, 1.21 to 2.84; P<.005) after accounting for these confounders. The risk of MACE was attenuated in those with reduced CRF alone after additionally adjusting for adequate adherence to PAP (HR=1.59; 95% CI, 0.77 to 3.31; P=.21).

CONCLUSION

The incidence of MACE, especially mortality, was high in this sample. Moderate-to-severe SDB with concurrent decreased CRF was associated with higher risk of MACE than decreased CRF alone. These results highlight the importance of possibly including CRF in the risk assessment of patients with SDB and, conversely, that of screening for SDB in patients with low peak VO₂.

Aerobic, Resistance, and Combination Training on Health-Related Quality of Life: The STRRIDE-AT/RT Randomized Trial

Purpose: The main purpose of this study was to determine the differential effects of aerobic training (AT), resistance training (RT), and a combination of aerobic and resistance training (AT/RT) on changes in self-rated HrQoL measures, including the Short-Form 36 (SF-36) survey and Satisfaction with Physical Function and Appearance survey. We also sought to determine if combination training (AT/RT) has a more or less additive effect compared to AT or RT alone on self-rated HrQoL measures. Materials and Methods: Participants (n = 137) completed one of three 8-month exercise interventions: (1) AT: 14 kcal exercise expenditure per kg of body weight per week (KKW; equivalent to roughly 12 miles/week) at 65-80% of peak oxygen consumption; (2) RT: 3 days per week, 8 exercises, 3 sets per exercise, 8-12 repetitions per set; (3) AT/RT: full combination of the AT and RT interventions. The SF-36 survey, Satisfaction with Physical Function and Appearance survey, physical fitness, and anthropometrics were assessed at baseline and post-intervention. Paired t-tests determined significant pre- vs. post-intervention scores within groups (p < 0.05). Analyses of covariance determined differences in change scores among groups (p < 0.05). Results: On average, participants were 49.0 ± 10.6 years old, obese (BMI: 30.6 ± 3.2 kg/m²), female (57.7%), and Caucasian (84.7%). Following the 8-month intervention, exercise groups improved peak VO₂ (all groups), strength (RT and AT/RT), and anthropometric measures (AT and AT/RT). For the SF-36, RT (p = 0.03) and AT/RT (p < 0.001) significantly improved their physical component score; only AT/RT (p < 0.001) significantly improved their mental component score. Notably, all groups significantly improved both their satisfaction with physical function and appearance scores (All Groups: p < 0.001 for both outcomes). Conclusions: We found that aerobic, resistance, or combination exercise training improves several components of self-rated HrQoL, including physical function, appearance, and mental well-being. Clinical Trial Registration: No. NCT00275145.

Effects of Amount, Intensity, and Mode of Exercise Training on Insulin Resistance and Type 2 Diabetes Risk in the STRRIDE Randomized Trials

Background

Lipoprotein Insulin Resistance Index (LP-IR) and Diabetes Risk Index are novel spectroscopic multimarkers of insulin resistance and type 2 diabetes risk. As the Studies of a Targeted Risk Reduction Intervention through Defined Exercise (STRRIDE) randomized trials have previously demonstrated the ability of exercise training to improve traditional markers of insulin action, the aim of this study was to examine the effects of exercise amount, intensity, and mode on LP-IR and the Diabetes Risk Index.

Methods

A total of 503 adults with dyslipidemia [STRRIDE I (n = 194), STRRIDE AT/RT (n = 139)] or prediabetes [STRRIDE-PD (n = 170)] were randomized to control or one of 10 exercise interventions, ranging from doses of 8–23 kcal/kg/week; intensities of 50–75% V̇O_2peak; and durations of 6–8 months. Two groups included resistance training and one included dietary intervention (7% weight loss goal). Fasting plasma samples were obtained at baseline and 16–24 h after the final exercise bout. LP-IR, the Diabetes Risk Index, and concentrations of the branched chain amino acids valine and leucine were determined using nuclear magnetic resonance spectroscopy. LP-IR and the Diabetes Risk Index scores range from 0–100 and 1–100, respectively (greater scores indicate greater risk). Paired t-tests determined significance within groups (p < 0.05).

Results

After training, six exercise groups significantly improved LP-IR (ranging from −4.4 ± 8.2 to −12.4 ± 14.1), and four exercise groups significantly improved the Diabetes Risk Index (ranging from −2.8 ± 8.2 to −8.3 ± 10.4). The most beneficial interventions for both LP-IR and the Diabetes Risk Index were low amount/moderate intensity aerobic, aerobic plus resistance, and aerobic plus diet.

Summary

Multiple exercise interventions improved LP-IR and the Diabetes Risk Index. In those with dyslipidemia, adding resistance to aerobic training elicited a synergistic effect on insulin resistance and type 2 diabetes risk. In individuals with prediabetes, combining a dietary intervention and weight loss with aerobic training resulted in the most robust type 2 diabetes risk improvement.

Prognostic Relevance of Cardiorespiratory Fitness as Assessed by Submaximal Exercise Testing for All-Cause Mortality: A UK Biobank Prospective Study

OBJECTIVE

To investigate whether the inverse associations of cardiorespiratory fitness (CRF) with all-cause and cardiovascular mortality in the general population vary among individuals who are at different levels of pretest risk.

PATIENTS AND METHODS

Cardiorespiratory fitness was assessed through submaximal bicycle tests in 58,892 participants aged 40 to 69 years who completed baseline questionnaires between January 1, 2006, and December 31, 2010, in the UK Biobank Prospective Study. Participants were categorized into risk categories, which determined allocation to an individualized bicycle protocol. The groups at minimal risk (category 1), small risk (category 2), and medium risk (category 3) were tested at 50%, 35% of the predicted maximal workload, and constant level, respectively. We investigated associations of CRF with mortality across different levels of pretest risk and determined whether CRF improves risk prediction.

RESULTS

During a median follow-up of 5.8 years, 936 deaths occurred. Cardiorespiratory fitness was linearly associated with mortality risk. Comparing extreme fifths of CRF, the multivariable-adjusted hazard ratios (95% CIs) for mortality were 0.63 (0.52-0.77), 0.54 (0.36-0.82), 0.81 (0.46-1.43), and 0.58 (0.48-0.69) in categories 1, 2, and 3 and overall population, respectively. The addition of CRF to a 5-year mortality risk score containing established risk factors was associated with a C-index change (0.0012; P=.49), integrated discrimination improvement (0.0005; P<.001), net reclassification improvement (+0.0361; P=.005), and improved goodness of fit (likelihood ratio test, P<.001). Differences in 5-year survival were more pronounced across levels of age, smoking status, and sex.

CONCLUSION

Cardiorespiratory fitness, assessed by submaximal exercise testing, improves mortality risk prediction beyond conventional risk factors and its prognostic relevance varies across cardiovascular risk levels.

Association of Adherence to Specific Mediterranean Diet Components and Cardiorespiratory Fitness in Young Adults

OBJECTIVE

Cardiorespiratory fitness (CRF) and a healthy diet may be part of an overall healthy lifestyle. The association between cardiorespiratory fitness and adherence to an overall Mediterranean Diet (MedD) pattern and specific MedD foods has been assessed.

DESIGN

Subjects completed a lifestyle survey and dietary pattern, using the validated MedD Adherence 14-item questionnaire and two self-reported 24-h dietary recalls. Participants' height, body weight, waist circumference (WC), and CRF (maximum oxygen uptake, VO2max, ml/kg/min) were measured.

SETTING

University of Cádiz, Spain.

SUBJECTS

A sample of young adults (n = 275, 22.2 ± 6.3 years).

RESULTS

Mean VO2max was 43.9 mL/kg/min (SD 8.5 mL/kg/min). Most participants had healthy CRF (75.9%). The average MedD score was 6.2 points (SD 1.8 points). Participants who consumed more servings of nuts had higher VO2max. Those who showed low CRF performed less physical activity (PA) and had a higher body mass index (BMI) and WC compared with those classified as having healthy CRF. Nut consumption was positively associated with VO2max (β = 0.320; 95% CI 2.4, 10.7; p < 0.002), adjusting for sex, age, smoking PA, BMI, WC, and energy intake, showing the subjects who consumed more nuts were fitter than young adults who consumed less.

CONCLUSIONS

CRF is positively associated with nut consumption but not with the overall MedD pattern and all other MedD foods in the young adults. The subjects who consumed more servings of nuts were fitter than young adults who consumed less. Moreover, fitter subjects performed more PA and had a lower BMI and WC than those who had lower fitness levels.

No Differences in Active Young Adults’ Affective Valence or Enjoyment Between Rowing and Cycling

Regular participation in continuous exercise modalities including running, walking, cycling, and rowing is an effective way to satisfy public health recommendations for moderate intensity continuous training. Rowing and cycling are each nonweight bearing, yet they differ, based on the size of muscle mass required. As it is unknown whether this discrepancy alters participants’ perceptual responses to exercise, this study examined differences in affective valence and enjoyment between rowing and cycling. Active men and women ( N = 22; Mage = 27.4, SD =7.7 years; Mbody mass index = 23.6, SD =  2.8 kg/m2) initially performed incremental exercise on the cycle ergometer and rowing ergometer to assess maximal oxygen uptake. During two subsequent sessions, they performed 30 minutes of graded exercise on either modality at intensities equal to 60-65%, 70-75%, and 80-85% maximal heart rate, during which we measured affective valence (Feeling Scale), rating of perceived exertion (RPE: 6–20), and enjoyment. Results showed a significant increase in RPE ( p < .001) and decrease in affective valence ( p <  .001) during exercise, but no difference in RPE, affective valence, or enjoyment in response to cycling versus rowing. In total, nine participants preferred cycling to rowing, while 13 preferred rowing to cycling. Overall, rowing and cycling elicit similar changes in RPE, affective valence, and enjoyment. Future work is needed to assess the applicability of these findings to larger and more diverse populations.

Evaluating Individual Level Responses to Exercise for Health Outcomes in Overweight or Obese Adults

Background

Understanding group responses to a given exercise exposure is becoming better developed; however, understanding of individual responses to specific exercise exposures is significantly underdeveloped and must advance before personalized exercise medicine can become a functional reality. Herein, utilizing data from the STRRIDE studies, we address some of the key issues surrounding our efforts to develop better understanding of individual exercise responsiveness.

Methods

We assessed individual cardiometabolic and cardiorespiratory fitness responses in subjects successfully completing STRRIDE I (n = 227) and STRRIDE II (n = 155). Subjects were previously sedentary, overweight or obese men and women with mild-to-moderate dyslipidemia. Subjects were randomized to either an inactive control group or to an exercise training program. Training groups varied to test the differential effects of exercise amount, intensity, and mode on cardiometabolic health outcomes. Measures included fasting plasma glucose, insulin, and lipids; blood pressure, minimal waist circumference, visceral adipose tissue, and peak VO₂. Absolute change scores were calculated for each subject as post-intervention minus pre-intervention values in order to evaluate the heterogeneity of health factor responsiveness to exercise training.

Results

For subjects completing one of the aerobic training programs, change in peak VO₂ ranged from a loss of 37% to a gain of 77%. When ranked by magnitude of change, we observed discordant responses among changes in peak VO₂ with changes in visceral adipose tissue, HDL-C, triglycerides, and fasting plasma insulin. There was also not a clear, direct relationship observed between magnitudes of individual response in the aforementioned variables with aerobic training adherence levels. This same pattern of highly variable and discordant responses was displayed even when considering subjects with adherence levels greater than 70%.

Conclusion

Our findings illustrate the unclear relationship between magnitude of individual response for a given outcome with training adherence and specific exercise exposure. These discordant and heterogeneous responses highlight the difficult nature of developing understanding for how individuals will respond to any given exposure. Further investigation into the biological, physiological, and genetics factors affecting individual responsiveness is vital to making personalized exercise medicine a reality.

Exercise and Cardiovascular Risk among Masters Athletes with Type 2 Diabetes

PURPOSE OF REVIEW

This review was designed to provide a scientific and clinical framework for the care of physically active men and women with an emphasis on the management of T2DM.

RECENT FINDINGS

The preventative and therapeutic benefits of physical activity (PA) on adult onset or Type 2 Diabetes Mellitus (T2DM) are well established. Individuals diagnosed with or are at risk for T2DM should be counseled and maximally supported to pursue an active or athletic lifestyle. Optimally, this translates into the adoption of an athletic lifestyle. "Masters athletes", men and women above the age of 35 who regularly train for and/or participate in competitive sport, represent a rapidly growing segment of the population. Although the high level of exercise characteristic of this population has numerous health benefits, it does not confer immunity from T2DM or cardiovascular (CV) disease. Providing effective care for men and women above the age of 35 who regularly train for and/or participate in competitive sport requires an understanding of the interplay between basic exercise physiology and the pathogenesis of insulin resistance.

Validity of simplified, calibration-less exercise intensity measurement using resting heart rate during sleep: a method-comparison study with respiratory gas analysis

Background

The recent development of wearable devices has enabled easy and continuous measurement of heart rate (HR). Exercise intensity can be calculated from HR with indices such as percent HR reserve (%HRR); however, this requires an accurate measurement of resting HR, which can be time-consuming. The use of HR during sleep may be a substitute that considers the calibration-less measurement of %HRR. This study examined the validity of %HRR on resting HR during sleep in comparison to percent oxygen consumption reserve (%VO₂R) as a gold standard. Additionally, a 24/7%HRR measurement using this method is demonstrated.

Methods

Twelve healthy adults aged 29 ± 5 years underwent treadmill testing using the Bruce protocol and a 6-min walk test (6MWT). The %VO₂R during each test was calculated according to a standard protocol. The %HRR during each exercise test was calculated either from resting HR in a sitting position (%HRR_sitting), when lying awake (%HRR_lying), or during sleep (%HRR_sleeping). Differences between %VO₂R and %HRR values were examined using Bland-Altman plots. A 180-day, 24/7%HRR measurement with three healthy adults was also conducted. The %HRR values during working days and holidays were compared.

Results

In the treadmill testing, the mean difference between %VO₂R and %HRR_sleeping was 1.7% (95% confidence interval [CI], − 0.2 to 3.6%). The %HRR_sitting and %HRR_lying values were 10.8% (95% CI, 8.8 to 12.7%) and 7.7% (95% CI, 5.4 to 9.9%), respectively. In the 6MWT, mean differences between %VO₂R and %HRR_sitting, %HRR_lying and %HRR_sleeping were 12.7% (95% CI, 10.0 to 15.5%), 7.0% (95% CI, 4.0 to 10.0%) and − 2.9% (95% CI, − 5.0% to − 0.7%), respectively. The 180-day, 24/7%HRR measurement presented significant differences in %HRR patterns between working days and holidays in all three participants.

Conclusions

The results suggest %HRR_sleeping is valid in comparison to %VO₂R. The results may encourage a calibration-less, 24/7 measurement model of exercise intensity using wearable devices.

Trial registration

UMIN000034967.

Registered 21 November 2018 (retrospectively registered).

Similar perceptual responses to reduced exertion high intensity interval training (REHIT) in adults differing in cardiorespiratory fitness

Reduced exertion high intensity interval training (REHIT) is an extremely low-volume approach of sprint interval exercise (SIE) that increases maximal oxygen uptake (VO₂max) and reduces body fat. However, there are concerns regarding implementation of SIE including REHIT in untrained populations due to generation of supramaximal power outputs and potential feelings of displeasure. This study examined perceptual responses to a single REHIT session in adults with above (n = 43, VO₂max = 41 ± 6 mL/kg/min) and below average VO₂max (n = 42, VO₂max = 33 ± 5 mL/kg/min). Initially, incremental exercise was completed to determine VO₂max. Subsequently, participants completed REHIT consisting of two 20 s "all-out" sprints at resistance equal to 5 % body mass. Rating of perceived exertion (RPE), affective valence, and physical activity enjoyment (PACES) were determined. Tolerance and preference to exercise intensity were also measured to examine if they moderated the responses. Compared to participants with below average VO₂max, those with above average VO₂max revealed similar change in affective valence (p = 0.86), RPE (p = 0.41), and enjoyment (p = 0.64) despite attaining significantly higher peak and mean power output in response to REHIT. The lowest value of affective valence ranged from 1.0-1.5, representing "fairly good." Overall, one session of REHIT elicits positive affective valence and similar pleasure:displeasure and enjoyment responses in individuals having diverse cardiorespiratory fitness, although we recommend that REHIT should be individualized for each client as greater frequency of aversive responses was shown in our participants with low fitness.

Short-Term Changes in Cardiorespiratory Fitness in Response to Exercise Training and the Association with Long-Term Cardiorespiratory Fitness Decline: The STRRIDE Reunion Study

Background

Substantial heterogeneity exists in the cardiorespiratory fitness (CRF) change in response to exercise training, and its long‐term prognostic implication is not well understood. We evaluated the association between the short‐term supervised training‐related changes in CRF and CRF levels 10 years later.

Methods and Results

STRRIDE (Studies of a Targeted Risk Reduction Intervention Through Defined Exercise) trial participants who were originally randomized to exercise training for 8 months and participated in the 10‐year follow‐up visit were included. CRF levels were measured at baseline, after training (8 months), and at 10‐year follow‐up as peak oxygen uptake (vo₂, mL/kg per min) using the maximal treadmill test. Participants were stratified into low, moderate, and high CRF response groups according to the training regimen–specific tertiles of CRF change. The study included 80 participants (age: 52 years; 35% female). At 10‐year follow‐up, the high‐response CRF group had the least decline in CRF compared with the moderate‐ and low‐response CRF groups (−0.35 versus −2.20 and −4.25 mL/kg per minute, respectively; P=0.02). This result was largely related to the differential age‐related changes in peak oxygen pulse across the 3 groups (0.58, −0.23, and −0.86 mL/beat, respectively; P=0.03) with no difference in the peak heart rate change. In adjusted linear regression analysis, high response was significantly associated with greater CRF at follow‐up independent of other baseline characteristics (high versus low [reference] CRF response: standard β=0.25; P=0.004).

Conclusions

Greater CRF improvement in response to short‐term training is associated with higher CRF levels 10 years later. Lack of CRF improvements in response to short‐term training may identify individuals at risk for exaggerated CRF decline with aging.

The Potential Impact of Probiotics on the Gut Microbiome of Athletes

There is accumulating evidence that physical fitness influences the gut microbiome and as a result, promotes health. Indeed, exercise-induced alterations in the gut microbiome can influence health parameters crucial to athletic performance, specifically, immune function, lower susceptibility to infection, inflammatory response and tissue repair. Consequently, maintenance of a healthy gut microbiome is essential for an athlete's health, training and performance. This review explores the effect of exercise on the microbiome while also investigating the effect of probiotics on various potential consequences associated with over-training in athletes, as well as their associated health benefits.

Blood Lactate Concentration Is Not Related to the Increase in Cardiorespiratory Fitness Induced by High Intensity Interval Training

Background: There is individual responsiveness to exercise training as not all individuals experience increases in maximal oxygen uptake (VO₂max), which does not benefit health status considering the association between VO₂max and mortality. Approximately 50% of the training response is genetic, with the other 50% accounted for by variations in dietary intake, sleep, recovery, and the metabolic stress of training. This study examined if the blood lactate (BLa) response to high intensity interval training (HIIT) as well as habitual dietary intake and sleep duration are associated with the resultant change in VO₂max (ΔVO₂max). Methods: Fourteen individuals (age and VO₂max = 27 ± 8 years and 38 ± 4 mL/kg/min, respectively) performed nine sessions of HIIT at 130% ventilatory threshold. BLa was measured during the first and last session of training. In addition, sleep duration and energy intake were assessed. Results: Data showed that VO₂max increased with HIIT (p = 0.007). No associations occurred between ΔVO₂max and BLa (r = 0.44, p = 0.10), energy intake (r = 0.38, p = 0.18), or sleep duration (r = 0.14, p = 0.62). However, there was a significant association between training heart rate (HR) and ΔVO₂max (r = 0.62, p = 0.02). Conclusions: When HIIT is prescribed according to a metabolic threshold, energy intake, sleep status, and BLa do not predict ΔVO₂max, yet the HR response to training is associated with the ΔVO₂max.

Verification testing to confirm VO2max attainment in persons with spinal cord injury

Context/Objective: Maximal oxygen uptake (VO₂max) is a widely used measure of cardiorespiratory fitness, aerobic function, and overall health risk. Although VO₂max has been measured for almost 100 yr, no standardized criteria exist to verify VO₂max attainment. Studies document that incidence of 'true' VO₂max obtained from incremental exercise (INC) can be confirmed using a subsequent verification test (VER). In this study, we examined efficacy of VER in persons with spinal cord injury (SCI). Design: Repeated measures, within-subjects study. Setting: University laboratory in San Diego, CA. Participants: Ten individuals (age and injury duration = 33.3 ± 10.5 yr and 6.8 ± 6.2 yr) with SCI and 10 able-bodied (AB) individuals (age = 24.1 ± 7.4 yr). Interventions: Peak oxygen uptake (VO₂peak) was determined during INC on an arm ergometer followed by VER at 105 percent of peak power output (% PPO). Outcome Measures: Gas exchange data, heart rate (HR), and blood lactate concentration (BLa) were measured during exercise. Results: Across all participants, VO₂peak was highly related between protocols (ICC = 0.98) and the mean difference was equal to 0.08 ± 0.11 L/min. Compared to INC, VO₂peak from VER was not different in SCI (1.30 ± 0.45 L/min vs. 1.31 ± 0.43 L/min) but higher in AB (1.63 ± 0.40 L/min vs. 1.76 ± 0.40 L/min). Conclusion: Data show similar VO₂peak between incremental and verification tests in SCI, suggesting that VER confirms VO₂max attainment. However, in AB participants completing arm ergometry, VER is essential to validate appearance of 'true' VO₂peak.

Effects of Exercise to Improve Cardiovascular Health

Obesity is a complex disease that affects whole body metabolism and is associated with an increased risk of cardiovascular disease (CVD) and Type 2 diabetes (T2D). Physical exercise results in numerous health benefits and is an important tool to combat obesity and its co-morbidities, including cardiovascular disease. Exercise prevents both the onset and development of cardiovascular disease and is an important therapeutic tool to improve outcomes for patients with cardiovascular disease. Some benefits of exercise include enhanced mitochondrial function, restoration and improvement of vasculature, and the release of myokines from skeletal muscle that preserve or augment cardiovascular function. In this review we will discuss the mechanisms through which exercise promotes cardiovascular health.

Does sex mediate the affective response to high intensity interval exercise?

High intensity interval exercise (HIIE) is identified as an alternative to moderate intensity continuous exercise (MICE) due to its similar effects on outcomes including maximal oxygen uptake and glycemic control. Nevertheless, its widespread implementation in adults is questioned because acute HIIE elicits more aversive responses (negative affective valence) than MICE which may make it impractical to perform long-term. Differences in muscle mass, fiber type, and substrate utilization exist between men and women that alter physiological responses which may cause differences in affective valence, yet the effect of sex on this outcome is unresolved. This study compared changes in affective valence between active men and women (mean age = 24.0 ± 4.8 yr) performing HIIE and sprint interval exercise (SIE) on a cycle ergometer. Affect (+5 to -5), rating of perceived exertion (RPE 1-10), and blood lactate concentration (BLa) were measured before and throughout exercise, and enjoyment was assessed post-exercise. Results showed that women exhibit more positive affect (p < .05) during HIIE and SIE than men (0.6-1.8 units higher values). In addition, women exhibited lower BLa (p = .003) than men during SIE (11.8 ± 2.4 mM vs. 14.9 ± 3.1 mM). In contrast, there was no effect of sex on RPE (p = .32 and p = .54) or enjoyment (p = .24 and p = .37) in response to HIIE or SIE. Practitioners should consider the sex of their clients when assessing change in affective valence induced by interval-based exercise.

The Effects of Exercise and Physical Activity on Weight Loss and Maintenance

Obesity represents a major health problem in the United States and is associated with increased prevalence of cardiovascular (CV) disease risk factors. Physical activity (PA) and exercise training (ET) are associated with reduced CV risk, improved cardiometabolic risk factors, and facilitated weight loss through creating a negative energy balance. Clinicians need to counsel overweight and obese patients on how much PA/ET is needed to promote weight loss and weight loss maintenance. This will help establish realistic expectations and maximize improvements in CV risk factors. Although the minimum guidelines for aerobic PA (150 min of moderate or 75 min of vigorous physical activity per week) can improve CV health, these levels are generally inadequate for clinically significant weight loss or weight maintenance without caloric restriction. The purpose of this review is to evaluate the role of ET to promote clinically significant weight loss and promote weight maintenance. In particular, we will evaluate the likelihood of weight loss from ET programs composed of aerobic training only, resistance training only and programs that combine diet and ET. We will also explore the role of PA in promoting short-term and long-term weight maintenance.

Genetic Variation in Acid Ceramidase Predicts Non-completion of an Exercise Intervention

Genetic variation is associated with a number of lifestyle behaviours; it may be associated with adherence and individual responses to exercise training. We tested single nucleotide polymorphisms (SNPs) in the acid ceramidase gene (ASAH1) for association with subject adherence and physiologic benefit with exercise training in two well-characterised randomised, controlled 8-month exercise interventions: STRRIDE I (n = 239) and STRRIDE II (n = 246). Three ASAH1 non-coding SNPs in a linkage disequilibrium block were associated with non-completion: rs2898458(G/T), rs7508(A/G), and rs3810(A/G) were associated with non-completion in both additive (OR = 1.8, 1.8, 2.0; P < 0.05 all) and dominant (OR = 2.5, 2.6, 3.5; P < 0.05 all) models; with less skeletal muscle ASAH expression (p < 0.01) in a subset (N = 60); and poorer training response in cardiorespiratory fitness (peak VO₂ change rs3810 r² = 0.29, P = 0.04; rs2898458 r² = 0.29, P = 0.08; rs7508 r² = 0.28, p = 0.09); and similar in direction and magnitude in both independent exploratory and replication studies. Adherence to exercise may be partly biologically and genetically moderated through metabolic regulatory pathways participating in skeletal muscle adaptation to exercise training.

Effects of aerobic training with and without weight loss on insulin sensitivity and lipids

Purpose

The purpose of this study is to evaluate the effect of exercise training with modest or greater weight loss (≥3%) or not (<3%) on insulin sensitivity, lipoprotein concentrations, and lipoprotein particle size in overweight and obese participants.

Methods

Adults (N = 163, body mass index: 25–37 [kg/m²]) participated in 8 months of exercise training. Insulin sensitivity, lipid concentrations, lipid particle size and other cardiometabolic variables were measured at baseline and follow-up. Participants were categorized by whether they achieved at least modest weight loss (≥ 3%) or not (<3%) following the intervention.

Results

A greater improvement in insulin sensitivity was observed in adults performing exercise training with at least modest weight loss (2.2 mU·l^-1 ·min ^-1, CI: 1.5 to 2.8) compared to those who did not (0.8 mU·l^-1 ·min ^-1, CI: 0.5 to 1.2). Similar results were observed for acute insulin response, triglycerides, non-HDL cholesterol concentration, low density lipoprotein (LDL) particle size and high density lipoprotein (HDL) particle size (p<0.05), when all exercise groups were combined. No significant results across weight loss categories were observed for LDL, HDL, glucose, or insulin levels.

Conclusion

The present study suggests that aerobic exercise combined with at least modest weight loss leads to greater improvements in insulin sensitivity, triglycerides as well as other non-traditional lipid risk factors (non-HDL cholesterol, HDL/LDL particle size). Clinicians should advocate patients who are overweight/obese to exercise and obtain modest weight loss for improved cardiovascular benefits.

Effects of a 12-week mHealth program on peak VO2 and physical activity patterns after completing cardiac rehabilitation: A randomized controlled trial

BACKGROUND

Site-based cardiac rehabilitation (CR) provides supervised exercise, education and motivation for patients. Graduates of CR have improved exercise tolerance. However, when participation in CR ceases, adherence to regular physical activity often declines, consequently leading to worsening risk factors and clinical events. Therefore, the purpose of this pilot study was to evaluate if a mHealth program could sustain the fitness and physical activity levels gained during CR.

METHODS AND RESULTS

A 12-week mHealth program was implemented using physical activity trackers and health coaching. Twenty-five patients were randomized into mHealth or usual care after completing CR. The combination of a 4.7±13.8% increase in the mHealth and a 8.5±11.5% decrease in the usual care group resulted in a difference between groups (P≤.05) for absolute peak VO₂. Usual care decreased the amount of moderate-low physical activity minutes per week (117±78 vs 50±53; P<.05) as well as moderate-high (111±87 vs 65±64; P<.05). mHealth increased moderate-high physical activity (138±113 vs 159±156; NS). The divergent changes between mHealth and usual care in moderate-high physical activity minutes/week resulted in a difference between groups (21±103 vs - 46±36; P<.05).

CONCLUSIONS

A 12-week mHealth program of physical activity trackers and health coaching following CR graduation can sustain the gains in peak VO₂ and physical activity achieved by site-based CR.

CARDIORESPIRATORY FITNESS AND CARDIOMETABOLIC RISK FACTORS AMONG UNIVERSITY PROFESSORS

ABSTRACT Introduction: Cardiorespiratory fitness (CF) is associated with mortality and the development of cardiovascular disease, in addition to being related to work capacity. Objectives: This study aimed to verify the demographic, cardiometabolic and behavioral factors associated with CF in a representative sample of professors from a public university in Minas Gerais, Brazil. Methods: This is a cross-sectional study which evaluated, in addition to the CF, age, sex, glycemia, triglycerides, LDL and HDL cholesterol, C-reactive protein, body mass index (BMI), waist circumference, and physical activity (PA). The association between CF and cardiometabolic risk factors was estimated by logistic regression to obtain the odds ratios and respective confidence intervals (95%). Results: After adjustment, it was observed that professors with lower levels of CF were older, female, had higher BMI and a greater chance of being physically inactive. Conclusion: In general, the results show that the probability of low CF increases with the increase in BMI, in addition to the strong association with PA practice, which is a major focus of intervention measures aimed at improving workers health and their work capacity. Level of Evidence III; Case control study.

Mechanism for temporal changes in exercise capacity after Fontan palliation: Role of Doppler echocardiography

BACKGROUND

The objective was to better understand Doppler hemodynamics and exercise capacity in patients with Fontan palliation by delineating the hemodynamic mechanism for temporal changes in their peak oxygen consumption (V̇o₂).

METHODS

We performed a retrospective review of adult Fontan patients with systemic left ventricle (LV) who underwent serial transthoracic echocardiograms (TTE) and cardiopulmonary exercise tests (CPET) at Mayo Clinic in 2000-2015. TTE and CPET data were used (1) to determine agreement between V̇o₂ and Doppler-derived LV function indices (eg, stroke volume index [SVI] and cardiac index [CI]) and (2) to determine agreement between temporal changes in peak V̇o₂ and LV function indices.

RESULTS

Seventy-five patients (44 men; 59%) underwent 191 pairs of TTE and CPET. At baseline, mean age was 24±3 years, peak V̇o₂ was 22.9±4.1 mL/kg/min (63±11 percent predicted), SVI was 43±15 mL/m², and CI was 2.9±0.9 L/min/m². Peak V̇o₂ correlated with SVI (r=0.30, P<.001) and with CI (r=0.45, P<.001) in the 153 pairs of TTE and CPET in patients without cirrhosis. Temporal changes in percent predicted peak V̇o₂ correlated with changes in SVI (r=0.48, P=.005) and CI (r=0.49, P=.004) among the 33 patients without interventions during the study. In the 19 patients with Fontan conversion, percent predicted peak V̇o₂ and chronotropic index improved.

CONCLUSIONS

Overall, there was a temporal decline in peak V̇o₂ that correlated with decline in Doppler SVI. In the patients who had Fontan conversion operation, there was a temporal improvement in peak V̇o₂ that correlated with improvement in chronotropic index.

Effect of Number of Sprints in an SIT Session on Change in V˙O2max: A Meta-analysis

PURPOSE

Recent meta-analyses indicate that sprint interval training (SIT) improves cardiorespiratory fitness (V˙O2max), but the effects of various training parameters on the magnitude of the improvement remain unknown. The present meta-analysis examined the modifying effect of the number of sprint repetitions in an SIT session on improvements in V˙O2max.

METHODS

The databases PubMed and Web of Science were searched for original studies that have examined pre- and posttraining V˙O2max in adults after ≥2 wk of training consisting of repeated (≥2) Wingate-type cycle sprints, published up to May 1, 2016. Articles were excluded if they were not in English; if they involved patients, athletes, or participants with a mean baseline V˙O2max of >55 mL·kg·min or a mean age <18 yr; and if an SIT trial was combined with another intervention or used intervals shorter than 10 s. A total of 38 SIT trials from 34 studies were included in the meta-analysis. Probabilistic magnitude-based inferences were made to interpret the outcome of the analysis.

RESULTS

The meta-analysis revealed a likely large effect of a typical SIT intervention on V˙O2max (mean ± 90% confidence limits = 7.8% ± 4.0%) with a possibly small modifying effect of the maximum number of sprint repetitions in a training session (-1.2% ± 0.8% decrease per two additional sprint repetitions). Apart from possibly small effects of baseline V˙O2max and age, all other modifying effects were unclear or trivial.

CONCLUSION

We conclude that the improvement in V˙O2max with SIT is not attenuated with fewer sprint repetitions, and possibly even enhanced. This means that SIT protocols can be made more time efficient, which may help SIT to be developed into a viable strategy to impact public health.

Changes in fat oxidation in response to various regimes of high intensity interval training (HIIT)

Increased whole-body fat oxidation (FOx) has been consistently demonstrated in response to moderate intensity continuous exercise training. Completion of high intensity interval training (HIIT) and its more intense form, sprint interval training (SIT), has also been reported to increase FOx in different populations. An explanation for this increase in FOx is primarily peripheral adaptations via improvements in mitochondrial content and function. However, studies examining changes in FOx are less common in response to HIIT or SIT than those determining increases in maximal oxygen uptake which is concerning, considering that FOx has been identified as a predictor of weight gain and glycemic control. In this review, we explored physiological and methodological issues underpinning existing literature concerning changes in FOx in response to HIIT and SIT. Our results show that completion of interval training increases FOx in approximately 50% of studies, with the frequency of increased FOx higher in response to studies using HIIT compared to SIT. Significant increases in β-HAD, citrate synthase, fatty acid binding protein, or FAT/CD36 are likely responsible for the greater FOx seen in these studies. We encourage scientists to adopt strict methodological procedures to attenuate day-to-day variability in FOx, which is dramatic, and develop standardized procedures for assessing FOx, which may improve detection of changes in FOx in response to HIIT.

Physical activity and central adiposity in a cohort of African-American adults

Background

Visceral adipose tissue (VAT) is known as an independent predictor of cardiometabolic risk and all-cause mortality, while increased physical activity has been shown to improve cardiometabolic risk. The purpose of the present study was to determine whether or not there is an association between objectively-measured physical activity and VAT in a community-based cohort of African-American adults, a population at higher-than-average risk for cardiometabolic diseases.

Methods

Free-living physical activity was quantified using accelerometry while VAT and abdominal subcutaneous fat were estimated using dual x-ray absorptiometry in a cohort of African Americans, ages 30–50 years, enrolled in the Modeling the Epidemiologic Transition Study. Univariate and multivariate analyses were used to determine the degree of association comparing moderate-to-vigorous physical activity (MVPA), vigorous activity, and sedentary behavior with measures of central adiposity including VAT, subcutaneous fat, and waist circumference.

Results

A total of 271 individuals with complete data were included in the analyses. Women, on average, had significantly more VAT and abdominal subcutaneous fat than men. There were statistically significant inverse univariate correlations between MVPA and measures of abdominal adiposity (−0.30, p < 0.001) and activity counts and adiposity (−0.31, p < 0.001) among both sexes. These significant associations remained after controlling for age, sex, and smoking status; neither alcohol consumption nor employment status were associated with abdominal adiposity. Time in sedentary behavior was not meaningfully associated with central adiposity in either sex (women: −0.02, p = 0.79; men: −0.21, p = 0.04).

Conclusions

To our knowledge, this study is the first to identify significant inverse associations between MVPA and measures of central adiposity among African American adults from a community-based cohort using an objective measure of physical activity and a validated quantitative imaging technique.

The Effect of Vigorous- Versus Moderate-Intensity Aerobic Exercise on Insulin Action

Due to the beneficial effects on a wide range of modern medical conditions, most professional societies recommend regular aerobic exercise as part of a healthy lifestyle. Many of the exercise-related health benefits exhibit a dose-response relationship: Up to a point, more exercise is more beneficial. However, recent studies have suggested that different exercise intensities may provide distinct health benefits, independent of energy expenditure (i.e., exercise dose). One of these benefits, primarily mediated by the skeletal muscle, is exercise-related changes in insulin action and glucose homeostasis. Glucose uptake in the exercising muscle occurs through insulin-independent mechanisms whose downstream signaling events ultimately converge with insulin-signaling pathways, a fact that may explain why exercise and insulin have additive effect on skeletal muscle glucose uptake. Although the existing evidence is somewhat conflicting, well-controlled randomized studies suggest that, when controlled for total energy expenditure, moderate-intensity aerobic exercise improves insulin sensitivity more than vigorous-intensity aerobic exercise. The mechanisms underlying this difference are largely unknown. One possible explanation involves enhanced metabolism of fatty acid stores in the skeletal muscle by moderate-intensity exercise, which may directly improve insulin sensitivity. Overall, new technologic and physiologic investigative tools are beginning to shed light on the biology. Further understanding of these mechanisms will lead to better understanding of the clinical implications of a healthy lifestyle and may ultimately offer new therapeutic targets for common medical conditions such as insulin resistance and diabetes.

Voluntary physical exercise protects against behavioral and endocrine reactivity to social and environmental stressors in the prairie vole

Physical activity can combat detrimental effects of stress. The current study examined the potential protective effects of exercise against a combination of social isolation and chronic mild stress (CMS) in a prairie vole model. Female voles were isolated for 4 weeks, with the addition of CMS during the final 2 weeks. Half of the voles were allowed access to a running wheel during this final 2 weeks, while the other half remained sedentary. Animals underwent behavioral tests to assess depressive- and anxiety-behaviors. In a subset of animals, plasma was collected 10 minutes after behavioral testing for corticosterone analysis. In a separate subset, brains were collected 2 hours after behavioral testing for cFos analysis in the paraventricular nucleus (PVN). Voles in the exercise group displayed significantly lower depressive- and anxiety-behaviors, and displayed significantly lower corticosterone levels, compared to animals in the sedentary group. There was no difference in PVN cFos activity between groups. Interestingly, animals that moderately exercised displayed lower levels of depressive-behavior and attenuated corticosterone reactivity compared to animals in the low and high activity subgroups. These findings suggest that physical activity can protect against a combination of social and environmental stressors.

Association of the Composite Inflammatory Biomarker GlycA, with Exercise-Induced Changes in Body Habitus in Men and Women with Prediabetes

GlycA is a new composite measure of systemic inflammation and a predictor of many inflammatory diseases. GlycA is the nuclear magnetic resonance spectroscopy-derived signal arising from glucosamine residues on acute-phase proteins. This study aimed to evaluate how exercise-based lifestyle interventions modulate GlycA in persons at risk for type 2 diabetes. GlycA, fitness, and body habitus were measured in 169 sedentary adults (45–75 years) with prediabetes randomly assigned to one of four six-month exercise-based lifestyle interventions. Interventions included exercise prescription based on the amount (energy expenditure (kcal/kg weight/week (KKW)) and intensity (%VO_2peak). The groups were (1) low-amount/moderate-intensity (10KKW/50%) exercise; (2) high-amount/moderate-intensity (16KKW/50%) exercise; (3) high-amount/vigorous-intensity (16KKW/75%) exercise; and (4) a Clinical Lifestyle (combined diet plus low-amount/moderate-intensity exercise) intervention. Six months of exercise training and/or diet-reduced GlycA (mean Δ: −6.8 ± 29.2 μmol/L; p = 0.006) and increased VO_2peak (mean Δ: 1.98 ± 2.6 mL/kg/min; p < 0.001). Further, visceral (mean Δ: −21.1 ± 36.6 cm²) and subcutaneous fat (mean Δ: −24.3 ± 41.0 cm²) were reduced, while liver density (mean Δ: +2.3 ± 6.5HU) increased, all p < 0.001. When including individuals in all four interventions, GlycA reductions were associated with reductions in visceral adiposity (p < 0.03). Exercise-based lifestyle interventions reduced GlycA concentrations through mechanisms related to exercise-induced modulations of visceral adiposity. This trial is registered with Clinical Trial Registration Number NCT00962962.

The association between physical activity and risk of mortality is modulated by grip strength and cardiorespiratory fitness: evidence from 498 135 UK-Biobank participants

Aims

It is unclear whether the potential benefits of physical activity differ according to level of cardiorespiratory fitness (CRF) or strength. The aim of this study was to determine whether the association between physical activity and mortality is moderated by CRF and grip strength sufficiently to inform health promotion strategies.

Methods and Results

498 135 participants (54.7% women) from the UK Biobank were included (CRF data available in 67 702 participants). Exposure variables were grip strength, CRF, and physical activity. All-cause mortality and cardiovascular disease (CVD) events were the outcomes. 8591 died over median 4.9 years [IQR 4.3–5.5] follow-up. There was a significant interaction between total physical activity and grip strength (P < 0.0001) whereby the higher hazard of mortality associated with lower physical activity was greatest among participants in the lowest tertile for grip strength (hazard ratio, HR:1.11 [95% CI 1.09–1.14]) and lowest among those in the highest grip strength tertile (HR:1.04 [1.01–1.08]). The interaction with CRF did not reach statistical significance but the pattern was similar. The association between physical activity and mortality was larger among those in the lowest tertile of CRF (HR:1.13 [1.02–1.26]) than those in the highest (HR:1.03 [0.91–1.16]). The pattern for CVD events was similar.

Conclusions

These data provide novel evidence that strength, and possibly CRF, moderate the association between physical activity and mortality. The association between physical activity and mortality is strongest in those with the lowest strength (which is easily measured), and the lowest CRF, suggesting that these sub-groups could benefit most from interventions to increase physical activity.

A Practical and Time-Efficient High-Intensity Interval Training Program Modifies Cardio-Metabolic Risk Factors in Adults with Risk Factors for Type II Diabetes

INTRODUCTION

Regular physical activity (PA) can reduce the risk of developing type 2 diabetes, but adherence to time-orientated (150 min week^-1 or more) PA guidelines is very poor. A practical and time-efficient PA regime that was equally efficacious at controlling risk factors for cardio-metabolic disease is one solution to this problem. Herein, we evaluate a new time-efficient and genuinely practical high-intensity interval training (HIT) protocol in men and women with pre-existing risk factors for type 2 diabetes.

MATERIALS AND METHODS

One hundred eighty-nine sedentary women (n = 101) and men (n = 88) with impaired glucose tolerance and/or a body mass index >27 kg m^-2 [mean (range) age: 36 (18-53) years] participated in this multi-center study. Each completed a fully supervised 6-week HIT protocol at work-loads equivalent to ~100 or ~125% [Formula: see text]. Change in [Formula: see text] was used to monitor protocol efficacy, while Actiheart™ monitors were used to determine PA during four, weeklong, periods. Mean arterial (blood) pressure (MAP) and fasting insulin resistance [homeostatic model assessment (HOMA)-IR] represent key health biomarker outcomes.

RESULTS

The higher intensity bouts (~125% [Formula: see text]) used during a 5-by-1 min HIT protocol resulted in a robust increase in [Formula: see text] (136 participants, +10.0%, p < 0.001; large size effect). 5-by-1 HIT reduced MAP (~3%; p < 0.001) and HOMA-IR (~16%; p < 0.01). Physiological responses were similar in men and women while a sizeable proportion of the training-induced changes in [Formula: see text], MAP, and HOMA-IR was retained 3 weeks after cessation of training. The supervised HIT sessions accounted for the entire quantifiable increase in PA, and this equated to 400 metabolic equivalent (MET) min week^-1. Meta-analysis indicated that 5-by-1 HIT matched the efficacy and variability of a time-consuming 30-week PA program on [Formula: see text], MAP, and HOMA-IR.

CONCLUSION

With a total time-commitment of <15 min per session and reliance on a practical ergometer protocol, 5-by-1 HIT offers a new solution to modulate cardio-metabolic risk factors in adults with pre-existing risk factors for type 2 diabetes while approximately meeting the MET min week^-1 PA guidelines. Long-term randomized controlled studies will be required to quantify the ability for 5-by-1 HIT to reduce the incidence of type 2 diabetes, while strategies are required to harmonize the adaptations to exercise across individuals.