Impact of data analysis methods for maximal fat oxidation estimation during exercise in sedentary adults

Abstract

The maximal fat oxidation (MFO), and the exercise intensity that elicits MFO (Fat_max), are considered excellent markers of fat metabolism during exercise. Besides individual’s biological characteristics (e.g. fed state, physical fitness level, sex, or age), data selection and analysis can affect MFO and Fatmax estimations, yet the effect is unknown. We investigated (i) the impact of using a pre-defined time interval on MFO and Fat_max estimation, and (ii) the impact of applying 2 different data analysis approaches (measured-values vs. polynomial-curve) on MFO and Fat_max estimations in sedentary adults. A total of 151 (97 women) sedentary adults aged 29.2?±?13.2 years old participated in the study. We assessed MFO and Fatmax through a walking graded exercise test using indirect calorimetry. We pre-defined 13 different time intervals for data analysis, and the estimation of MFO and Fat_max were performed through the measured-values and the polynomial-curve data analysis approaches. There were significant differences in MFO across pre-defined time intervals methods (P?<?0.001) applying measured-values data analysis approach, while no statistical differences were observed when using polynomial-curve data analysis approach (P?=?0.077). There were no differences in Fat_max across pre-defined time intervals independently of the data analysis approach (P?≥?0.7). We observed significant differences in MFO between measured-values and the polynomial-curve data analysis approaches across the time intervals methods selected (all P?≤?0.05), and no differences were observed in Fat_max (all P?≥?0.2). In conclusion, our results revealed that there are no differences in MFO and Fat_max across different time intervals methods selected using the polynomial-curve data analysis approach. We observed significant differences in MFO between measured-values vs. polynomial-curve data analysis approaches in all the study time intervals, whereas no differences were detected in Fatmax. Therefore, the use of polynomial-curve data analysis approach allows to compare MFO and Fat_max using different time intervals in sedentary adults.     

A short bout of high-intensity intermittent exercise before moderate-intensity prolonged exercise as a mean to potentiate fat oxidation ?

ABSTRACT

Moderate-intensity continuous exercise (MICE) improves fat oxidation. High-intensity intermittent exercise (HIIE) is thought to have a greater potential for fat oxidation but it might be too demanding in the long term for patients. We hypothesized that an initial bout of HIIE could maximize fat oxidation during MICE and the following passive recovery. Eighteen healthy participants performed two acute isocaloric exercise sessions at random. MICE consisted of 45-min cycling at 50% of maximal aerobic power (Pmax). COMB began with five 1-min bouts of HIIE at Pmax (interspaced with 1-min recovery periods) followed by 35-min MICE. Gas exchange allowed substrate oxidation rate assessment.

Expressed as a % of energy expenditure, fat oxidation (%) increased during in the passive recovery following COMB (Recovery: 36.0 ± 19.4 vs 23.0 ± 20.3%; ES: 0.66; p < 0.0001). An initial bout of HIIE preceding a prolonged moderate-intensity exercise may potentiate fat oxidation during the following recovery. This might be relevant for health management of overweight/obese persons.     

膳食脂肪对运动能力的影响及运动时脂代谢的调节

就膳食脂肪对运动能力的影响以及脂肪代谢的调节作一综述。运动强度、时间不同，脂肪供能所占的比例不同，脂肪供能对运动成绩的影响也有所差异。运动时脂代谢的调节受多种因素的影响，激素敏感性甘油三酯脂肪酶(HSL)是酶解速度的主要控制因素。     

运动与肥胖状态下睾酮生物合成的关系

肥胖会导致体内血浆瘦素水平升高,发生瘦素抵抗,进而影响机体的物质和能量代谢,瘦素还可直接作用于睾丸间质细胞影响睾酮的生物合成;而运动作为一种应激因素,可影响雄性生殖系统的功能。本文阐述了肥胖状态下由瘦素作用的JAK-STAT对睾酮传导通路各级蛋白的影响,以及运动干预对各级联蛋白含量的影响。     

有氧运动对肥胖妇女血清瘦素、脂联素的影响

目的:研究12周有氧训练对肥胖妇女血清瘦素、脂联素水平的影响,及它们与体成分和脂代谢的关系.方法:对15名肥胖妇女(年龄为38.3±5.6岁,BMI为28.36±1.73)进行12周有氧训练干预,并于实验前测试体成分、血脂、瘦素和脂联素等指标.结果:12周有氧训练后,受试者的体重、BMI、体脂百分比、甘油三酯、游离脂肪酸和血清瘦素水平有了显著性的下降;血清脂联素水平有了显著性的上升.血清瘦素的变化量与体脂百分比的变化量相关.血清脂联素的变化量与体重的变化量相关.结论:12周有氧训练有效地改善了肥胖妇女的体成分和血脂水平;促进了血清瘦素和脂联素的良性变化;血清瘦素和脂联素的变化与体重的变化密切相关.     

耐力运动对幼年肥胖大鼠血清瘦素水平的影响

为观察耐力运动对幼年肥胖大鼠血清瘦素的影响,将30只6周龄雄性SD肥胖大鼠随机分成肥胖对照组、45min游泳组及90min游泳组,另10只正常体重同龄SD大鼠为正常对照组。除正常对照组饲普通饲料外,其余各组均饲高脂饲料。两个运动组大鼠分别以每天1次,每次45min和90min游泳,每周6天,持续12周。实验结束后测定血TG、TC、HDL、LDL及血清瘦素。结果显示:12周耐力运动使肥胖大鼠血清TG、LDL显著降低,血清HDL显著升高;两个运动组大鼠体重增加总量明显低于两个对照组(P<0.05);肥胖对照组表现为高瘦素血症,两个运动组肥胖大鼠血清瘦素水平显著下降(P<0.01)。结果说明:耐力运动使肥胖大鼠血清TG、LDL显著降低,血清HDL显著升高;耐力运动可降低血清瘦素水平,有效地改善幼年肥胖大鼠的高瘦素血症。     

Effect of supramaximal exercise training on metabolic outcomes in obese adults

The purpose of this study was to evaluate the effects of 6 weeks of supramaximal exercise training (SET) on performance variables and metabolic changes in sedentary obese adults.

Twenty-four obese adults were randomly allocated into a non-trained (NT) [n = 12; body mass index (BMI) = 33(3)] and SET group [n = 12; BMI = (33(2)]. After baseline metabolic and fitness measurements, the participants completed a 6-week SET intervention. Metabolic, anthropometric, and fitness assessments were repeated post-intervention.

For SET, fasting glucose (4.64(0.15) vs. 4.32(0.22) mmol · l^–1; P < 0.01), insulin (23.2(4.6) vs. 13.8(3.3) µmol · ml^–1; P < 0.01), homoeostasis model assessment-insulin resistance index (4.78(1.2) vs. 2.65(1.5); P < 0.01) and systolic blood pressure (127(3) vs. 120(3) mmHg; P < 0.01) were significantly lower 24-h post-intervention than at baseline and for the NT group, and these changes remained significant at 72-h and 2-weeks post-intervention (P < 0.01, respectively). Interestingly, nonesterified fatty acids (0.62(0.09) vs. 0.71(0.11) mmol · l^–1; P < 0.01) and resting fat oxidation rate (57(11) vs. 63(4)%; P < 0.01) increased significantly from baseline 24-h post-intervention in the SET group and from baseline at 72-h (P < 0.01, respectively) and 2-weeks post-intervention (P < 0.01, respectively). Six weeks of SET improved a number of metabolic and vascular risk factors in obese, sedentary adults, highlighting the potential of SET to provide an alternative exercise model for the improvement of metabolic health in this population.     

Acute coordinative exercise ameliorates general and food-cue related cognitive function in obese adolescents

ABSTRACT

Whether the acute coordinative exercise could affect the inhibitory control and food-cue related attention in obese adolescents remains understudied. Therefore, this study used the Stroop test and the food-cue related Stroop test to explore the impacts of 20 min of acute coordinative exercise on the cognitive tests involving inhibitory control and attentional bias towards food-cue related stimuli, respectively, in obese adolescents. Thirty-eight obese adolescents (mean age = 14.63 ± 0.69 years) were equally divided into exercise and control groups. The cognitive tests (i.e., the Stroop test and the food-cue related Stroop test) and hunger scores were conducted and assessed before and after an intervention. The exercise group had significantly larger negative pre-post response time difference in the congruent (?1.04 ± 0.29 ms) and incongruent (?5.76 ± 1.66 ms) conditions of the Stroop test than the control group (ps < 0.01), and a smaller post-interference (1.13 ± 0.14) than the pre-interference (1.31 ± 0.14, p = 0.04). Moreover, a significantly larger negative pre-post response time difference on the food-cue related Stroop test was observed in the exercise group (?4.42 ± 7.20 ms) than the control group (1.76 ± 8.37 ms, p = 0.02). Collectively, an acute coordinative exercise session could induce superior inhibitory control and less attentional bias towards food-cue related stimuli in obese adolescents.     

High-intensity interval training programme for obese youth (HIP4YOUTH): A pilot feasibility study

Recently, there has been growing interest in high-intensity interval training (HIT) as a strategy to improve health. In this pilot study, we examined the feasibility of a 4-week low-volume HIT and its effects on cardiorespiratory fitness (CRF), blood pressure (BP) and enjoyment in overweight and obese youth. Twelve adolescents (body mass index (BMI): 34.8 ± 3.9 kg · m^?2, 14.9 ± 1.5 years) participated in 12 sessions of HIT (10 × 60 s cycling bouts eliciting ~90% maximal heart rate, interspersed with 90 s recovery, 30 min/session, 3 sessions/week) over ~4 weeks. All the participants completed the study and exercise attendance averaged 92%. Despite no changes in body weight and total fat, HIT resulted in significant (P < 0.01) increases in CRF (pre: 20.1 versus post: 22.2 ml · kg^?1 · min^?1) and exercise time (pre: 425 versus post: 509 s) during peak oxygen uptake test, and a reduction in resting systolic BP (pre: 115.8 versus post: 107.6 mmHg). The majority of study participants (83%) enjoyed HIT and more than half of the participants (58%) reported that HIT is a more enjoyable form of exercise compared to other types of exercises. Low-volume HIT is a useful strategy to promote exercise participation and improve cardiovascular health in overweight and obese youth.     

Effects of an 8-weeks erythropoietin treatment on mitochondrial and whole body fat oxidation capacity during exercise in healthy males

The present investigation was performed to elucidate if the non-erythropoietic ergogenic effect of a recombinant erythropoietin treatment results in an impact on skeletal muscle mitochondrial and whole body fatty acid oxidation capacity during exercise, myoglobin concentration and angiogenesis. Recombinant erythropoietin was administered by subcutaneous injections (5000 IU) in six healthy male volunteers (aged 21 ± 2 years; fat mass 18.5 ± 2.3%) over 8 weeks. The participants performed two graded cycle ergometer exercise tests before and after the intervention where VO_2max and maximal fat oxidation were measured. Biopsies of the vastus lateralis muscle were obtained before and after the intervention. Recombinant erythropoietin treatment increased mitochondrial O₂ flux during ADP stimulated state 3 respiration in the presence of complex I and II substrates (malate, glutamate, pyruvate, succinate) with additional electron input from β-oxidation (octanoylcarnitine) (from 60 ± 13 to 87 ± 24 pmol · s^?1 · mg^?1 P < 0.01). β-hydroxy-acyl-CoA-dehydrogenase activity was higher after treatment (P < 0.05), whereas citrate synthase activity also tended to increase (P = 0.06). Total myoglobin increased by 16.5% (P < 0.05). Capillaries per muscle area tended to increase (P = 0.07), whereas capillaries per fibre as well as the total expression of vascular endothelial growth factor remained unchanged. Whole body maximal fat oxidation was not increased after treatment. Eight weeks of recombinant erythropoietin treatment increases mitochondrial fatty acid oxidation capacity and myoglobin concentration without any effect on whole body maximal fat oxidation.     

Effects of short-term exercise training on tissue Doppler indices of left ventricular diastolic function in overweight and obese individuals

Abstract

Although exercise training is unable to improve obesity-associated decreases in left ventricular (LV) diastolic function, as assessed using chamber function measurements, the effects on LV diastolic myocardial function, as assessed using tissue Doppler imaging (TDI), are uncertain. In 32 overweight (n = 11) or obese (n = 21), sedentary or recreationally active men and women (30–57 years), we assessed the effects of 6 weeks of exercise training either preceded (n = 16) or followed (n = 16) by a 6-week control period on TDI indices of LV diastolic function (e', e'/a' and E/e') (echocardiography). Diastolic function at baseline was comparable to that noted in overweight and obese participants from a community sample (n = 245), and 56% (n = 18) had e' values below the lower 95% CI of a lean and healthy cohort (n = 60) of the community sample. Exercise training increased peak oxygen consumption (27.4 ± 4.9 to 29.4 ± 5.8 mL · kg^–1 · min^–1, P = 0.0001), but had no effect on body mass index (P = 0.99). No changes in TDI indices of diastolic function were observed after exercise training in all the participants (e': P = 0.74, a': P = 0.98, e'/a': P = 0.85, E/e': P = 0.26), participants with abnormal e' values (n = 18)(e': P = 0.99, a': P = 0.96, e'/a': P = 0.91, E/e': P = 0.97) or obese participants (n = 21)(e': P = 0.67, a': P = 1.00, e'/a': P = 0.78, E/e': P = 0.11). In conclusion, exercise training, despite increasing cardiorespiratory fitness, is unable to improve obesity-associated decreases in LV diastolic myocardial function.     

Oxygen uptake during mini trampoline exercise in normal-weight,endurance-trained adults and in overweight-obese,inactive adults: A proof-of-concept study

Objectives: To examine cardiorespiratory exertion during mini trampoline exercises of different intensities in both endurance-trained athletes and overweight-obese adults. Methods: Physically healthy participants (Group A: normal-weight, endurance-trained athletes; Group B: inactive, overweight-obese adults) participated in two measurement appointments and three training sessions in between appointments, in which participants familiarized themselves with the use of the mini trampoline and the execution of the exercises. The primary outcome was the ?O_2peak for each of the six mini trampoline exercises relative to the ?O_2peak as established during an all-out exercise test on a bike ergometer during the first measurement appointment. Secondary outcomes were average ?O₂ as well as maximum and average heart rate. Results: The six mini trampoline exercises generated ?O_2peak values between 42% and 81% in the endurance-trained athletes and between 58% and 87% in the overweight-obese participants, both in relation to the bike ergometer ?O_2peak. Average ?O₂ values ranged from 35% to 69% (endurance-trained athletes) and from 48% to 71% (overweight-obese participants), depending on exercise. Average heart rate likewise lay in a range that can be categorized as moderate-to-vigorous aerobic exercise for both groups. A moderate-to-strong correlation (0.658 to 0.875, depending on exercise) between bike ergometer ?O_2peak and mini trampoline ?O_2peak was found for all six exercises. Conclusions: Mini trampoline exercise has the potential to produce training intensities that concur with established exercise guidelines. The exercise intensity is self-adjusting and allows for an effective and safe workout for different users with a wide range of fitness levels.     

耐力运动中糖和脂肪利用的调节

耐力运动中要保持较高的输出功率必须同时利用糖和脂肪供能。事实上。机体内存在着复杂的机制调节糖和脂肪的利用。试从激素的调节、葡萄糖-脂肪酸循环及丙二酰CoA的调节三个方面来综述耐力运动中糖和脂肪利用的研究进展。     

RPE在中老年肥胖患者运动处方中的应用及相关影响因素分析

目的:探讨主观感觉疲劳量表(RPE)是否适用于中老年肥胖患者运动处方实施过程中运动强度的监控并分析影响RPE的相关因素。方法:215名中老年肥胖患者,进行递增负荷实验测试功能能力(F.C.,单位为代谢当量METs)和相应的RPE。以70%F.C.完成一次中等强度运动,同时记录患者的RPE值,比较用RPE推测的METs值和用递增负荷实验测得的METs值之间的差别。结果:受试者平均F.C.为6.1±1.8(METs),对应的RPE为15.2±1.6。RPE与BMI、性别、教育程度和抗心律失常药物有一定关联。70%F.C.为4.9±1.1(METs),而用RPE计算的预测值为5.6±1.2(METs),后者较前者高23.1%(P<0.01)。结论:在中老年肥胖患者实施运动处方的过程中,使用RPE会过高估计其实际运动强度;BMI、性别、教育程度和使用抗心律失常药物是RPE的影响变量。     

A preliminary evaluation of the associations among functional performance tasks and quality of life in obese and healthy weight youth

The associations among lower extremity functional performance and quality of life in obese youth are unknown. The aims of this study were to compare lower extremity strength, lower extremity functional performance, and health related quality of life between obese and healthy-weight youth and evaluate the relationships between lower extremity performance and health related quality of life in obese youth. Twenty obese and 20 age and sex matched healthy-weight youth were recruited. Peak torque of the major lower extremity muscles were measured. Functional performance was measured with single leg hop and single leg balance tests. The Paediatric Quality of Life questionnaire's physical and psychosocial health subscales were used. Paired t-tests and multiple regression analyses were performed. Obese youth demonstrated decreased peak torque in all muscles measured (P < 0.05), poorer functional performance (P < 0.05), and worse physical health related quality of life (P < 0.05) compared to healthy-weight youth. Lower extremity functional performance was associated with aspects of quality of life in the obese group (P = 0.002), but not in the healthy-weight group (P < 0.05). These results may assist in encouraging best practices in the promotion of exercise, physical activity, and quality of life in obese youth.     

运动减肥对肥胖症患者健康的促进作用

目前肥胖症的治疗方法主要有4种：单纯节食,药物减肥,手术去脂,运动减肥。运动减肥以小强度、长时间适宜的有氧运动,消耗体内的脂肪,达到减肥的目的。运动还可以增强体质、促进健康,具有其他减肥方法不可能达到的健康促进作用。文章介绍了运动减肥的3种模式：全封闭式运动减肥模式、运动减肥夏令营模式、公益性运动减肥模式;运动减肥操作常规,包括运动强度的确定、运动负荷试验、运动减肥运动项目的选择、运动减肥持续时间等问题。并通过众多的实验研究证实了运动减肥对肥胖症患者身体形态的改善作用、运动减肥对肥胖症患者脂肪肝的改善作用、运动减肥对血脂代谢的改善作用、运动减肥对肥胖症患者心脏功能的影响、运动减肥对肥胖症患者动脉粥样硬化致病因子的影响、运动减肥对肥胖症患者炎症因子与抗氧化能力的影响、运动减肥对肥胖症患者瘦素和脂联素的影响,综合阐述了运动减肥对肥胖症患者健康的促进作用。     

Feeling states during exercise: Influence of individual differences in perceived evaluative threat

Abstract

The present study is designed to examine the influence of individual differences in perceived evaluative threat and baseline responses on changes in feeling states experienced during acute exercise in college-age women with high social physique anxiety. Thirty women with high social physique anxiety completed acute bouts of stationary cycling at either a self-selected or imposed intensity in both naturalistic fitness centre and laboratory environments. Multivariate analysis of changes in feeling states during exercise yielded a significant baseline×perceived evaluative threat×intensity interaction during exercise in the naturalistic fitness centre environment. Decomposition of this interaction revealed that, within the naturalistic environment, women with the least favourable baseline feeling states who perceived the lowest amount of evaluative threat during exercise demonstrated the greatest improvements in affect during self-selected intensity exercise. These findings suggest that, among women with high social physique anxiety, changes in feeling states reported during exercise are influenced by an interaction between baseline affective responses, the intensity of exercise, and environmentally induced perceptions of evaluative threat.     

Effects of a phase change cooling garment during exercise in the heat

The purpose of our study was to examine the physiological, perceptual, and performance effects of wearing a phase change cooling garment (CG) during an interval exercise routine in the heat. Sixteen male participants (age 23?±?3 years, ht 1.76?±?0.11?m; wt 78.5?±?11.2?kg; body fat 15.2?±?5.8%) completed two trials (one with phase change inserts, CG, and one control without inserts) consisting of two submaximal exercise portions separated by 5-minute seated rest, and a final maximal effort performance bout. Each submaximal bout involved 30?seconds or 1?minute of muscular endurance and agility exercises and 5?minutes of treadmill jogging and step-ups. The performance bout included 30?seconds or 1?minute of muscular endurance and agility exercises, with participants completing as many repetitions as possible, followed by a 15-minute recovery (active and passive). Rectal temperature (T_re) and heart rate were not different between trials, however change in T_re from baseline was improved during 10 and 15 minutes of recovery with the CG (P?<?.05). Mean skin temperature was lower using the CG vs control throughout the trial (P?<?.05). Thermal sensation was lower when using the CG compared to control (P?<?.001). There were no differences in any outcomes of the performance exercises (P?>?.05). These findings indicate that the continuous use of a CG during an interval style workout in the heat provides improvements in thermal sensation, however, only minimal thermophysiological benefits, and no performance augmentation.     

Classification of obesity varies between body mass index and direct measures of body fat in boys and girls of Asian and European ancestry

Body mass index is a common proxy for proportion of body fat. However, body mass index may not classify youth similarly across ages and ethnicities. We used sex- and ethnic-specific receiver operating characteristic curves to determine how obesity classifications compared between body mass index and dual energy x-ray absorptiometry-based body fat percent. Male and female participants 9- to 18-years-old (n = 944; 487 female) were measured 1 to 13 times (1999–2012; 4,411 observations). Body mass index identified < 50% of those classified as obese from body fat percent. Specificity was 99.7%, and sensitivity was 35.8%. Using area under the curve and standard error values, body mass index performed significantly better for: Male versus female at 10 years, Asian versus European female except at 13-, 15-, and 16-years-old, Asian female versus male except at 10- and 15-years-old, and for European male versus female, 9- to 11-years-old (p < .05). Our findings provide evidence that users of body mass index should use caution when comparing body mass index across age, sex, and ethnicity.     

Influence of gender on ventilatory efficiency during exercise in young children

Abstract

In this study, we assessed the ventilatory response in 84 children (46 males: age 8.1 ± 1.0 years, body mass 34.2 ± 7.9 kg, height 1.32 ± 0.16 m; 38 females: age 8.0 ± 0.8 years, body mass 31.7 ± 8.7 kg, height 1.31 ± 0.08 m) during a cycle ergometer test to determine if there was an influence of gender on ventilatory efficiency. The test commenced at 25 W and increased by 10 W every minute. Expired air was collected through a face mask and analysed breath by breath. The ventilatory anaerobic threshold was determined according to gas exchange methods and we focused our attention on the analysis of carbon dioxide production ([Vdot]CO₂), ventilation ([Vdot] _E), the ratio [Vdot] _E/[Vdot]CO₂ and its slope. Differences between the sexes at maximal power output were strongly significant for [Vdot] _E and [Vdot]CO₂ (P = 0.0001 and P = 0.0004 respectively) and moderately significant for the [Vdot] _E/[Vdot]CO₂ ratio (P = 0.05). The slope of [Vdot] _E versus [Vdot]CO₂ was 30.8 ± 4.2 for males and 29.4 ± 3.2 for females, with no difference between the sexes (P = 0.1). In conclusion, although the peak values of [Vdot] _E and [Vdot]CO₂ were significantly different between the sexes, there were no such differences in ventilatory efficiency during a maximal incremental test expressed as the slope of [Vdot] _E/[Vdot]CO₂, at least in young children.