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Low-Frequency HIIT Improves Body Composition and Aerobic Capacity in Overweight Men.
Chin, EC, Yu, AP, Lai, CW, Fong, DY, Chan, DK, Wong, SH, Sun, F, Ngai, HH, Yung, PSH, Siu, PM
Medicine and science in sports and exercise. 2020;(1):56-66
Abstract
BACKGROUND The relationship between the frequency of high-intensity interval training (HIIT) and the resultant adaptations is largely unclear. PURPOSE This study compared the effects of different frequencies of HIIT with those of moderate-intensity continuous training (MICT) on body composition in overweight or obese adults. METHODS Fifty-six overweight or obese (body mass index = 26.4 ± 2.9) men between 18 and 30 yr old (age = 22.8 ± 3.1 yr) were randomly assigned to the following groups: no-intervention control (CON; n = 14), MICT performed thrice weekly (MICT×3/wk; n = 9), HIIT performed thrice weekly (HIIT×3/wk; n = 14), HIIT performed twice weekly (HIIT×2/wk; n = 10), and HIIT performed once weekly (HIIT×1/wk; n = 9). Each HIIT session consisted of 12 × 1-min bouts at 90% heart rate reserve, interspersed with 11 × 1-min bouts at 70% heart rate reserve. Aerobic capacity, body composition, resting heart rate, vascular function, insulin resistance, and biomarkers of metabolic syndrome risk factor were examined at baseline, after 4 wk, and after 8 wk of intervention. RESULTS Aerobic capacity and percent fat-free mass significantly increased in all exercise groups compared with those in the CON group (CON vs all exercise groups, P < 0.05), whereas body fat mass and systolic blood pressure significantly decreased after 8 wk of intervention in all exercise groups compared with those in the CON group (CON vs all exercise groups, P < 0.05). Body fat mass significantly decreased after 4 wk in all HIIT groups compared with those in the CON group (CON vs all HIIT groups, P < 0.05) but not in the MICT×3/wk group. CONCLUSION These novel results demonstrated that performing HIIT once weekly, even with a lower weekly volume of exercise, improved cardiorespiratory fitness, body composition, and blood pressure in overweight/obese adults. Low-frequency HIIT might be a feasible and effective strategy for the prescription of an initial exercise program for inactive, overweight, or obese young men.
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Physical Activity, Cardiorespiratory Fitness, and the Metabolic Syndrome.
Myers, J, Kokkinos, P, Nyelin, E
Nutrients. 2019;(7)
Abstract
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.
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3.
Reduced Exertion High-Intensity Interval Training is More Effective at Improving Cardiorespiratory Fitness and Cardiometabolic Health than Traditional Moderate-Intensity Continuous Training.
Cuddy, TF, Ramos, JS, Dalleck, LC
International journal of environmental research and public health. 2019;(3)
Abstract
This study sought to determine the effectiveness of an 8 wk reduced-exertion high-intensity interval training (REHIT) at improving cardiorespiratory fitness (CRF) and positively modifying cardiometabolic health in the workplace environment. Participants (n = 32) were randomized to two groups: (1) One group (n = 16) was prescribed an 8 wk REHIT program, and (2) one group (n = 16) was prescribed moderate-intensity continuous training (MICT). Cardiometabolic risk factors and CRF were measured at baseline and 8 wks. After 8 wks, changes in CRF (REHIT, 12%; MICT, 7%), systolic blood pressure (REHIT, -5%; MICT, -2%), waist circumference (REHIT, -1.4%; MICT, -0.3%), and metabolic syndrome (MetS) severity (MetS z-score: REHIT, -62%; MICT, 27%) were more favorable (p < 0.05) in the REHIT group relative to the MICT group. Interestingly, there was a significantly greater proportion of participants in the REHIT group (75%, 9/12) who had a favorable change in the MetS z-score (Δ > -0.60) relative to the MICT group (47%, 7/15). The main finding of the present study is that 8 wks REHIT elicited more potent and time-efficient improvements in CRF and cardiometabolic health when compared to traditional MICT. This study provides critical evidence for implementation of the sprint interval training (SIT) paradigm from the scientific literature into a real-world workplace setting.
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4.
Effectiveness of Aerobic Exercise Programs for Health Promotion in Metabolic Syndrome.
Morales-Palomo, F, Ramirez-Jimenez, M, Ortega, JF, Mora-Rodriguez, R
Medicine and science in sports and exercise. 2019;(9):1876-1883
Abstract
PURPOSE Continuous and interval are the two types of aerobic exercise training commonly used for health promotion. We sought to determine which aerobic exercise training program results in larger health improvements in metabolic syndrome (MetS) individuals. METHODS One hundred twenty-one MetS patients (age, 57 ± 8 yr; weight, 92 ± 15 kg; and MetS factors, 3.8 ± 0.8 components) with low initial cardiorespiratory fitness (CRF) (V˙O2peak, 24.0 ± 5.5 mL·kg·min) were randomized to undergo one of the following 16-wk exercise program: (a) 4 × 4-min high-intensity interval training at 90% of HRMAX (4HIIT group; n = 32), (b) 50-min moderate-intensity continuous training at 70% of HRMAX (MICT group; n = 35), (c) 10 × 1-min HIIT at 100% of HRMAX (1HIIT group; n = 32), or (d) no exercise control group (CONT; n = 22). We measured the evolution of all five MetS components (i.e., MetS Z Score) and CRF (assessed by V˙O2peak) before and after intervention. RESULTS MetS Z score decreased 41% after 4HIIT (95% confidence interval [CI], 0.25-0.06; P < 0.01) and 52% in MICT (95% CI, 0.24-0.06; P < 0.01), whereas it did not change in 1HIIT (decreased 24%; 95% CI, -0.16 to 0.03; P = 0.21) and CONT (increased 20%; 95% CI, -0.19 to 0.04; P = 0.22). However, the three exercise groups improved similarly their V˙O2peak (4HIIT, 11%; 95% CI, 0.14-0.33; MICT, 12%; 95% CI, 0.18-0.36; and 1HIIT, 14%; 95% CI, 0.21-0.40 L·min; all P < 0.001). CONCLUSIONS Our findings suggest that in sedentary individuals with MetS and low initial CRF level any aerobic training program of 16 wk with a frequency of three times per week is sufficient stimulus to raise CRF. However, the more intense but shorter 1HIIT training program is not effective on improving MetS Z score, and thus we caution its recommendation for health promotion purposes in this population.
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Is cardiorespiratory fitness impaired in PCOS women? A review of the literature.
Donà, S, Bacchi, E, Moghetti, P
Journal of endocrinological investigation. 2017;(5):463-469
Abstract
PURPOSE Polycystic ovary syndrome (PCOS) is a common and heterogeneous endocrine disorder, affecting 8-12% of reproductive-aged women. Insulin resistance and body fat excess are common features in these subjects. Increased physical activity and diet modifications are the first recommended approach in the management of these women, at least in overweight/obese subjects. Evaluation of cardiorespiratory fitness (CRF) is important in assessing exercise performance and in monitoring the effects of physical exercise interventions. Several studies have shown that CRF may be impaired in metabolic and endocrine disorders. However, there are little data on this issue in PCOS women. The aim of this narrative review is to critically evaluate whether aerobic capacity is altered in PCOS women, focusing on maximal oxygen uptake. METHODS An updated search of the literature was performed, identifying papers with maximal oxygen consumption measurements in women with PCOS compared to healthy controls. RESULTS We have identified six studies on this specific topic: four of them showed an alteration of maximal oxygen consumption in PCOS women, whereas two did not. However, taken together these studies suggest that CRF may be strikingly impaired in both normal-weight and overweight/obese subjects with this condition. CONCLUSIONS Women with PCOS appear to be characterized by a reduced cardiopulmonary fitness. However, further research on this topic is needed. This information may hopefully help clinicians and exercise specialist in planning individualized exercise programs aimed at improving the metabolic and endocrine outcomes in these women.
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Cardiorespiratory fitness is positively associated with increased pancreatic beta cell function independent of fatness in individuals with the metabolic syndrome: Fitness versus fatness.
Ramos, JS, Dalleck, LC, Borrani, F, Fassett, RG, Coombes, JS
Journal of science and medicine in sport. 2017;(1):45-49
Abstract
OBJECTIVES The vulnerability of individuals with the metabolic syndrome (MetS) to cardiovascular events (CVEs) is attenuated by increased cardiorespiratory fitness (CRF), despite the presence of obesity as a usual component of MetS. To better understand the importance of CRF and body fat in treating this condition, we investigated the relationship between fitness and fatness with pancreatic beta cell function (BCF) indices that are known independent predictors of CVEs. DESIGN Cross sectional study. METHODS This study included 84 individuals with MetS. BCF indices were derived from a fasted steady state (basal disposition index [DI], proinsulin, proinsulin:insulin, and proinsulin:C-peptide) and dynamic conditions via an oral glucose tolerance test (1st and 2nd phase DI). CRF and body fat percentage (BF%) were assessed via indirect calorimetry (during a maximal exercise test) and dual energy X-ray absorptiometry, respectively. RESULTS CRF was positively associated with basal DI (r=0.40, p<0.001), 1st phase DI (r=0.49, p<0.005), and 2nd phase DI (r=0.38, p=0.02). Hierarchical multiple regression analysis showed CRF was associated with basal DI (β=0.18, p=0.04), 1st phase DI (β=0.36, p=0.04), and 2nd phase DI (β=0.33, p=0.03), independent of BF% and other confounding factors including age, sex, diabetic status, anthropometric measures, lipid profile, and insulin sensitivity. No significant associations were found between CRF and proinsulin measures. BF% was not significantly correlated with BCF indices. CONCLUSIONS Increased CRF was independently associated with enhanced BCF. This study provides evidence that equal, if not more attention should be dedicated to CRF improvement relative to fat-loss for favorable pancreatic BCF and thus possible reduction in CV risk in individuals with MetS.
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7.
Cardiorespiratory Fitness and Adiposity as Determinants of Metabolic Health-Pooled Analysis of Two Twin Cohorts.
Jukarainen, S, Holst, R, Dalgård, C, Piirilä, P, Lundbom, J, Hakkarainen, A, Lundbom, N, Rissanen, A, Kaprio, J, Kyvik, KO, et al
The Journal of clinical endocrinology and metabolism. 2017;(5):1520-1528
Abstract
CONTEXT The joint effects of cardiorespiratory fitness (CRF) and body composition on metabolic health are not well known. OBJECTIVE To examine the associations of CRF, fat-free mass index (FFMI), and fat mass index (FMI) with metabolic health in individual twins and controlling for genetic and shared environmental effects by studying monozygotic intrapair differences. DESIGN, SETTING, AND PARTICIPANTS Two cross-sectional samples of healthy adult monozygotic and dizygotic twins were drawn from population-based Danish and Finnish national twin registries (n = 996 and n = 309). MAIN MEASURES CRF was defined as VO2max divided by fat-free mass. Insulin sensitivity and acute insulin response indices were derived from an oral glucose tolerance test. A continuous metabolic syndrome score was calculated. Visceral and liver fat were measured in the Finnish sample. Associations were analyzed separately in both cohorts with multivariate linear regression and aggregated with meta-analytic methods. RESULTS Insulin sensitivity, acute insulin response, metabolic syndrome score, visceral, and liver fat amount had strong and statistically significant associations with FMI (|β| 0.53 to 0.79), whereas their associations with CRF and FFMI were at most weak (|β| 0.02 to 0.15). The results of the monozygotic intrapair differences analysis showed the same pattern. CONCLUSIONS Although FMI is strongly associated with worsening of metabolic health traits, even after controlling for genetic and shared environmental factors, there was little evidence for the effects of CRF or FFMI on metabolic health. This suggests that changing FMI rather than CRF or FFMI may affect metabolic health irrespective of genetic or early environmental determinants.