To examine the effects of different protocols of high-intensity interval training (HIIT) on VO2max improvements in healthy, overweight/obese and athletic adults, based on the classifications of work ...intervals, session volumes and training periods.
Systematic review and meta-analysis.
PubMed, Scopus, Medline, and Web of Science databases were searched up to April 2018. Inclusion criteria were randomised controlled trials; healthy, overweight/obese or athletic adults; examined pre- and post-training VO2max/peak; HIIT in comparison to control or moderate intensity continuous training (MICT) groups.
Fifty-three studies met the eligibility criteria. Overall, the degree of change in VO2max induced by HIIT varied by populations (SMD=0.41–1.81, p<0.05). When compared to control groups, even short-intervals (≤30s), low-volume (≤5min) and short-term HIIT (≤4weeks) elicited clear beneficial effects (SMD=0.79–1.65, p<0.05) on VO2max/peak. However, long-interval (≥2min), high-volume (≥15min) and moderate to long-term (≥4–12weeks) HIIT displayed significantly larger effects on VO2max (SMD=0.50–2.48, p<0.05). When compared to MICT, only long-interval (≥2min), high-volume (≥15min) and moderate to long-term (≥4–12weeks) HIIT showed beneficial effects (SMD=0.65–1.07, p<0.05).
Short-intervals (≤30s), low-volume (≤5min) and short-term (≤4weeks) HIIT represent effective and time-efficient strategies for developing VO2max, especially for the general population. To maximize the training effects on VO2max, long-interval (≥2min), high-volume (≥15min) and moderate to long-term (≥4–12weeks) HIIT are recommended.
Both observational and interventional studies suggest an important role for physical activity and higher fitness in mitigating the metabolic syndrome. Each component of the metabolic syndrome is, to ...a certain extent, favorably influenced by interventions that include physical activity. Given that the prevalence of the metabolic syndrome and its individual components (particularly obesity and insulin resistance) has increased significantly in recent decades, guidelines from various professional organizations have called for greater efforts to reduce the incidence of this condition and its components. While physical activity interventions that lead to improved fitness cannot be expected to normalize insulin resistance, lipid disorders, or obesity, the combined effect of increasing activity on these risk markers, an improvement in fitness, or both, has been shown to have a major impact on health outcomes related to the metabolic syndrome. Exercise therapy is a cost-effective intervention to both prevent and mitigate the impact of the metabolic syndrome, but it remains underutilized. In the current article, an overview of the effects of physical activity and higher fitness on the metabolic syndrome is provided, along with a discussion of the mechanisms underlying the benefits of being more fit or more physically active in the prevention and treatment of the metabolic syndrome.
IMPORTANCE: Although the associations between cardiorespiratory fitness (CRF) and health in adults are well understood, to date, no systematic review has quantitatively examined the association ...between CRF during youth and health parameters later in life. OBJECTIVES: To examine the prospective association between CRF in childhood and adolescence and future health status and to assess whether changes in CRF are associated with future health status at least 1 year later. DATA SOURCES: For this systematic review and meta-analysis, MEDLINE, Embase, and SPORTDiscus electronic databases were searched for relevant articles published from database inception to January 30, 2020. STUDY SELECTION: The following inclusion criteria were used: CRF measured using a validated test and assessed at baseline and/or its change from baseline to the end of follow-up, healthy population with a mean age of 3 to 18 years at baseline, and prospective cohort design with a follow-up period of at least 1 year. DATA EXTRACTION AND SYNTHESIS: Data were processed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Random-effects models were used to estimate the pooled effect size. MAIN OUTCOMES AND MEASURES: Anthropometric and adiposity measurements and cardiometabolic health parameters. RESULTS: Fifty-five studies were included with a total of 37 563 youths (46% female). Weak-moderate associations were found between CRF at baseline and body mass index (r = –0.11; 95% CI, –0.18 to –0.04; I2 = 59.03), waist circumference (r = –0.29; 95% CI, –0.42 to –0.14; I2 = 69.42), skinfold thickness (r = –0.34; 95% CI, –0.41 to –0.26; I2 = 83.87), obesity (r = –0.15; 95% CI, –0.23 to –0.06; I2 = 86.75), total cholesterol level (r = –0.12; 95% CI, –0.19 to –0.05; I2 = 75.81), high-density lipoprotein cholesterol (HDL-C) level (r = 0.11; 95% CI, 0.05-0.18; I2 = 69.06), total cholesterol to HDL-C ratio (r = –0.19; 95% CI, –0.26 to –0.13; I2 = 67.07), triglyceride levels (r = –0.10; 95% CI, –0.18 to –0.02; I2 = 73.43), homeostasis model assessment for insulin resistance (r = –0.12; 95% CI, –0.18 to –0.06; I2 = 68.26), fasting insulin level (r = –0.07; 95% CI, –0.11 to –0.03; I2 = 0), and cardiometabolic risk (r = –0.18; 95% CI, –0.29 to –0.07; I2 = 90.61) at follow-up. Meta-regression analyses found that early associations in waist circumference (β = 0.014; 95% CI, 0.002-0.026), skinfold thickness (β = 0.006; 95% CI, 0.002-0.011), HDL-C level (β = −0.006; 95% CI, −0.011 to −0.001), triglyceride levels (β = 0.009; 95% CI, 0.004-0.014), and cardiometabolic risk (β = 0.007; 95% CI, 0.003-0.011) from baseline to follow-up dissipated over time. Weak-moderate associations were found between change in CRF and body mass index (r = –0.17; 95% CI, –0.24 to –0.11; I2 = 39.65), skinfold thickness (r = –0.36; 95% CI, –0.58 to –0.09; I2 = 96.84), obesity (r = –0.21; 95% CI, –0.35 to –0.06; I2 = 91.08), HDL-C level (r = 0.05; 95% CI, 0.02-0.08; I2 = 0), low-density lipoprotein cholesterol level (r = –0.06; 95% CI, –0.11 to –0.01; I2 = 58.94), and cardiometabolic risk (r = –0.08; 95% CI, –0.15 to –0.02; I2 = 69.53) later in life. CONCLUSIONS AND RELEVANCE: This study suggests that early intervention and prevention strategies that target youth CRF may be associated with maintaining health parameters in later life.
Intrinsic cardiorespiratory fitness (CRF) is defined as the level of CRF in the sedentary state. There are large individual differences in intrinsic CRF among sedentary adults. The physiology of ...variability in CRF has received much attention, but little is known about the genetic and molecular mechanisms that impact intrinsic CRF. These issues were explored in the present study by interrogating intrinsic CRF-associated DNA sequence variation and skeletal muscle gene expression data from the HERITAGE Family Study through an integrative bioinformatics guided approach. A combined analytic strategy involving genetic association, pathway enrichment, tissue-specific network structure, cis-regulatory genome effects, and expression quantitative trait loci was used to select and rank genes through a variation-adjusted weighted ranking scheme. Prioritized genes were further interrogated for corroborative evidence from knockout mouse phenotypes and relevant physiological traits from the HERITAGE cohort. The mean intrinsic V̇o
was 33.1 ml O
·kg
·min
(SD = 8.8) for the sample of 493 sedentary adults. Suggestive evidence was found for gene loci related to cardiovascular physiology (
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), skeletal muscle phenotypes (
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). Supportive evidence for a role of several of these loci was uncovered via association between DNA variants and muscle gene expression levels with exercise cardiovascular and muscle physiological traits. This initial effort to define the underlying molecular substrates of intrinsic CRF warrants further studies based on appropriate cohorts and study designs, complemented by functional investigations.
Intrinsic cardiorespiratory fitness (CRF) is measured in the sedentary state and is highly variable among sedentary adults. The physiology of variability in intrinsic cardiorespiratory fitness has received much attention, but little is known about the genetic and molecular mechanisms that impact intrinsic CRF. These issues were explored computationally in the present study, with further corroborative evidence obtained from analysis of phenotype data from knockout mouse models and human cardiovascular and skeletal muscle measurements.
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.
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.
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.
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.
There is a well-established inverse relationship between cardiorespiratory fitness (CRF) and mortality. However, this relationship has almost exclusively been studied using estimated CRF.
This study ...aimed to assess the association of directly measured CRF, obtained using cardiopulmonary exercise (CPX) testing with all-cause, cardiovascular disease (CVD), and cancer mortality in apparently healthy men and women.
Participants included 4,137 self-referred apparently healthy adults (2,326 men, 1,811 women; mean age: 42.8 ± 12.2 years) who underwent CPX testing to determine baseline CRF. Participants were followed for 24.2 ± 11.7 years (1.1 to 49.3 years) for mortality. Cox-proportional hazard models were performed to determine the relationship of CRF (ml·kg-1·min-1) and CRF level (low, moderate, and high) with mortality outcomes.
During follow-up, 727 participants died (524 men, 203 women). CPX-derived CRF was inversely related to all-cause, CVD, and cancer mortality. Low CRF was associated with higher risk for all-cause (hazard ratio HR: 1.73; 95% confidence interval CI: 1.20 to 3.50), CVD (HR: 2.27; 95% CI: 1.20 to 3.49), and cancer (HR: 2.07; 95% CI: 1.18 to 3.36) mortality compared with high CRF. Further, each metabolic equivalent increment increase in CRF was associated with a 11.6%, 16.1%, and 14.0% reductions in all-cause, CVD, and cancer mortality, respectively.
Given the prognostic ability of CPX-derived CRF for all-cause and disease-specific mortality outcomes, its use should be highly considered for apparently healthy populations as it may help to improve the efficacy of the individualized patient risk assessment and guide clinical decisions.
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To describe the process and outcomes of using a new evidence base to develop scientific guidelines that specify the type and minimum dose of exercise necessary to improve fitness and cardiometabolic ...health in adults with spinal cord injury (SCI).
International.
Using Appraisal of Guidelines, Research and Evaluation (AGREE) II reporting criteria, steps included (a) determining the guidelines' scope; (b) conducting a systematic review of relevant literature; (c) holding three consensus panel meetings (European, Canadian and International) to formulate the guidelines; (d) obtaining stakeholder feedback; and (e) process evaluation by an AGREE II consultant. Stakeholders were actively involved in steps (c) and (d).
For cardiorespiratory fitness and muscle strength benefits, adults with a SCI should engage in at least 20 min of moderate to vigorous intensity aerobic exercise 2 times per week AND 3 sets of strength exercises for each major functioning muscle group, at a moderate to vigorous intensity, 2 times per week (strong recommendation). For cardiometabolic health benefits, adults with a SCI are suggested to engage in at least 30 min of moderate to vigorous intensity aerobic exercise 3 times per week (conditional recommendation).
Through a systematic, rigorous, and participatory process involving international scientists and stakeholders, a new exercise guideline was formulated for cardiometabolic health benefits. A previously published SCI guideline was endorsed for achieving fitness benefits. These guidelines represent an important step toward international harmonization of exercise guidelines for adults with SCI, and a foundation for developing exercise policies and programs for people with SCI around the world.
Studies suggest that acute exercise may be beneficial for executive control (Hillman et al, 2003). This result appears especially in the incongruent condition of the flanker test, where inhibitory ...control is more necessary. In addition, evidence suggests that complementary cardiorespiratory activity is positively related to executive functions in childhood.
To analyze the relationship between cardiorespiratory fitness and inhibitory control and compare the acute effects of two HITT protocols on the inhibitory control of schoolchildren
This trial included 21 children in the 4th year of a municipal school in the city of Belém. Cardiorespiratory fitness was assessed using the 20-meter shuttle test. The volunteers ran at a pace set by a cell phone application that emitted beeps at specific intervals for each stage. The duration of the test depends on each person's cardiorespiratory fitness. Then, based on the level of cardiorespiratory fitness, the participants were divided into two groups (Good, n=10; Regular, n=11) The method used was the randomized crossover clinical trial, in which all participants performed two separate visits each other for a period of 72 hours. In each visit, the subjects were submitted to a different HIIT protocol: The Tabata protocol lasted 4 minutes with 8 series of 20 seconds of maximum effort and 10 seconds of rest. The Progressive protocol lasted 5 minutes, with 5 series of 20 seconds of maximum effort followed by 30,40,50,60 and 20 seconds of passive rest respectively, the exercises used body weight and consisted of squats, jumps and races. And to evaluate the inhibitory control, the computerized Flanker test was used. The test was applied at rest, before HIIT, and repeated 11 minutes after performing the exercises. Results were analyzed by estimation statistics and results expressed as significance (p), confidence interval (95%) and effect size (g). Congruent and incongruent response time (RT) were analyzed.
The group with higher cardiorespiratory conditioning showed better performance in the reaction time of the incongruent condition after performing the HIIT Tabata protocol (p= 0.0458, g= -0.451, 95.0%CI -0.822, -0.0689). However, the same effect was not observed in the group of children with lower cardiorespiratory fitness (p= 0.339 -0.213 95.0%CI -0.57, 0.357). No significant differences were found in the congruent condition of the inhibitory control test. The progressive HIIT protocol did not change the RT.
Our findings corroborate some previous findings that suggest that children with greater cardiorespiratory fitness respond more efficiently to an acute HIIT session by showing better inhibitory control
This study shows that HIIT Tabata can help improve inhibitory control in children with good cardiorespiratory fitness, being an easily accessible and short-term strategy that can be included in the routine of schools.
Aims/hypothesis
The study aimed to quantitatively summarise the dose–response relationships between cardiorespiratory fitness and muscular strength on the one hand and risk of type 2 diabetes on the ...other and estimate the hypothetical benefits associated with population-wide changes in the distribution of fitness.
Methods
We performed a systematic review with meta-analysis. The PubMed and EMBASE electronic databases were searched from inception dates to 12 December 2018 for cohort studies examining the association of cardiorespiratory fitness or muscular strength with risk of incident type 2 diabetes in adults. The quality of included studies was evaluated using the Newcastle–Ottawa Scale.
Results
Twenty-two studies of cardiorespiratory fitness and 13 studies of muscular strength were included in the systematic review with both exposures having ten estimates available for the primary adiposity- or body size-controlled meta-analysis. In random-effects meta-analysis including 40,286 incident cases of type 2 diabetes in 1,601,490 participants, each 1 metabolic equivalent (MET) higher cardiorespiratory fitness was associated with an 8% (95% CI 6%, 10%) lower RR of type 2 diabetes. The association was linear throughout the examined spectrum of cardiorespiratory fitness. In 39,233 cases and 1,713,468 participants each 1 SD higher muscular strength was associated with a 13% (95% CI 6%, 19%) lower RR of type 2 diabetes. We estimated that 4% to 21% of new annual cases of type 2 diabetes among 45–64-year-olds could be prevented by feasible and plausible population cardiorespiratory fitness changes.
Conclusions/interpretation
Relatively small increments in cardiorespiratory fitness and muscle strength were associated with clinically meaningful reductions in type 2 diabetes risk with indication of a linear dose–response relationship for cardiorespiratory fitness.
Registration:
PROSPERO (CRD42017064526).
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