Stefano Lanzi

Short‐term HIIT and Fatmax training increase aerobic and metabolic fitness in men with class II and III obesity

To compare the effects of two different 2‐week‐long training modalities [continuous at the intensity eliciting the maximal fat oxidation (Fatmax) versus high‐intensity interval training (HIIT)] in men with class II and III obesity.

Fat Oxidation, Hormonal and Plasma Metabolite Kinetics during a Submaximal Incremental Test in Lean and Obese Adults

This study aimed to compare fat oxidation, hormonal and plasma metabolite kinetics during exercise in lean (L) and obese (O) men. Sixteen L and 16 O men [Body Mass Index (BMI): 22.9±0.3 and 39.0±1.4 kg.m−2] performed a submaximal incremental test (Incr) on a cycle-ergometer. Fat oxidation rates (FORs) were determined using indirect calorimetry. A sinusoidal model, including 3 independent variables (dilatation, symmetry, translation), was used to describe fat oxidation kinetics and determine the intensity (Fatmax) eliciting maximal fat oxidation. Blood samples were drawn for the hormonal and plasma metabolite determination at each step of Incr. FORs (mg.FFM−1.min−1) were significantly higher from 20 to 30% of peak oxygen uptake () in O than in L and from 65 to 85% in L than in O (p≤0.05). FORs were similar in O and in L from 35 to 60% . Fatmax was 17% significantly lower in O than in L (p<0.01). Fat oxidation kinetics were characterized by similar translation, significantly lower dilatation and left-shift symmetry in O compared with L (p<0.05). During whole exercise, a blunted lipolysis was found in O [lower glycerol/fat mass (FM) in O than in L (p≤0.001)], likely associated with higher insulin concentrations in O than in L (p<0.01). Non-esterified fatty acids (NEFA) were significantly higher in O compared with L (p<0.05). Despite the blunted lipolysis, O presented higher NEFA availability, likely due to larger amounts of FM. Therefore, a lower Fatmax, a left-shifted and less dilated curve and a lower reliance on fat oxidation at high exercise intensities suggest that the difference in the fat oxidation kinetics is likely linked to impaired muscular capacity to oxidize NEFA in O. These results may have important implications for the appropriate exercise intensity prescription in training programs designed to optimize fat oxidation in O.

Long maximal incremental tests accurately assess aerobic fitness in class II and III obese men.

This study aimed to compare two different maximal incremental tests with different time durations [a maximal incremental ramp test with a short time duration (8-12 min) (STest) and a maximal incremental test with a longer time duration (20-25 min) (LTest)] to investigate whether an LTest accurately assesses aerobic fitness in class II and III obese men. Twenty obese men (BMI≥35 kg.m-2) without secondary pathologies (mean±SE; 36.7±1.9 yr; 41.8±0.7 kg*m-2) completed an STest (warm-up: 40 W; increment: 20 W*min-1) and an LTest [warm-up: 20% of the peak power output (PPO) reached during the STest; increment: 10% PPO every 5 min until 70% PPO was reached or until the respiratory exchange ratio reached 1.0, followed by 15 W.min-1 until exhaustion] on a cycle-ergometer to assess the peak oxygen uptake [Formula: see text] and peak heart rate (HRpeak) of each test. There were no significant differences in [Formula: see text] (STest: 3.1±0.1 L*min-1; LTest: 3.0±0.1 L*min-1) and HRpeak (STest: 174±4 bpm; LTest: 173±4 bpm) between the two tests. Bland-Altman plot analyses showed good agreement and Pearson product-moment and intra-class correlation coefficients showed a strong correlation between [Formula: see text] (r=0.81 for both; p≤0.001) and HRpeak (r=0.95 for both; p≤0.001) during both tests. [Formula: see text] and HRpeak assessments were not compromised by test duration in class II and III obese men. Therefore, we suggest that the LTest is a feasible test that accurately assesses aerobic fitness and may allow for the exercise intensity prescription and individualization that will lead to improved therapeutic approaches in treating obesity and severe obesity.

Effects of prior short multiple-sprint exercises with different intersprint recoveries on the slow component of oxygen uptake during high-intensity exercise.

This study compares the effects of two short multiple-sprint exercise (MSE) (6 × 6 s) sessions with two different recovery durations (30 s or 180 s) on the slow component of oxygen uptake ([Formula: see text]O(2)) during subsequent high-intensity exercise. Ten male subjects performed a 6-min cycling test at 50% of the difference between the gas exchange threshold and [Formula: see text]O(2peak) (Δ50). Then, the subjects performed two MSEs of 6 × 6 s separated by two intersprint recoveries of 30 s (MSE(30)) and 180 s (MSE(180)), followed 10 min later by the Δ50 (Δ50(30) and Δ50(180), respectively). Electromyography (EMG) activities of the vastus medialis and lateralis were measured throughout each exercise bout. During MSE(30), muscle activity (root mean square) increased significantly (p ≤ 0.04), with a significant leftward-shifted median frequency of the power density spectrum (MDF; p ≤ 0.01), whereas MDF was significantly rightward-shifted during MSE(180) (p = 0.02). The mean [Formula: see text]O(2) value was significantly higher in MSE(30) than in MSE(180) (p < 0.001). During Δ50(30), [Formula: see text]O(2) and the deoxygenated hemoglobin ([HHb]) slow components were significantly reduced (-27%, p = 0.02, and -34%, p = 0.003, respectively) compared with Δ50. There were no significant modifications of the [Formula: see text]O(2) slow component in Δ50(180) compared with Δ50 (p = 0.32). The neuromuscular and metabolic adaptations during MSE(30) (preferential activation of type I muscle fibers evidenced by decreased MDF and a greater aerobic metabolism contribution to the required energy demands), but not during MSE(180), may lead to reduced [Formula: see text]O(2) and [HHb] slow components, suggesting an alteration in motor units recruitment profile (i.e., change in the type of muscle fibers recruited) and (or) an improved muscle O(2) delivery during subsequent exercise.

Vascular Dynamics and Peripheral Oxygen Uptake in Obese Individuals during Progressive Physical Exercise

Background: Obese men show higher O2 consumption than lean men during physical exercise, with a trend toward higher peripheral O2 extraction; this is probably due to their larger muscle mass. Objectives: The aim of this study was to examine this phenomenon by measuring 2 vasoactive substances, endothelin-1 (ET-1) and nitric oxide (NO), during a progressive submaximal exercise. Methods: Seventeen obese (body mass index [BMI] 38.6) and 15 lean (BMI 22.5) men performed a maximal progressive cycle ergometer exercise to determine peak power output (PPO) and peak O2 consumption (V∙O2peak); thereafter, they performed a submaximal cycle ergometer incremental test (every 6 min) at the same percentage of V∙O2peak until they reached 57.5% PPO. Blood samples were collected at rest and at the end of every step to measure ET-1 and NO concentrations. Results: At rest, the ET-1 and NO concentrations in obese men and lean controls were the same. However, during exercise, the ET-1 concentration at each step was significantly lower (p < 0.05) in the obese group. There was no significant difference in NO concentration between the 2 groups, although the increase at the beginning of the exercise session was faster in obese individuals. During submaximal exercise, end-tidal O2 pressure (PETO2) was lower in the obese group, with a significant difference in the PETO2/fat-free mass ratio at each step. Conclusions: ET-1 and NO levels during physical exercise are different in obese versus lean men. This may support the notion that increased O2 consumption in obesity is due to different behaviors of the cardiorespiratory and circulatory systems.

Improving cardiometabolic and mental health in women with gestational diabetes mellitus and their offspring: study protocol for MySweetHeart Trial, a randomised controlled trial

Introduction Gestational diabetes mellitus (GDM) carries prenatal and perinatal risk for the mother and her offspring as well as longer-term risks for both the mother (obesity, diabetes, cardiovascular disease) and her child (obesity, type 2 diabetes). Compared with women without GDM, women with GDM are twice as likely to develop perinatal or postpartum depression. Lifestyle interventions for GDM are generally limited to physical activity and/or nutrition, often focus separately on the mother or the child and take place either during or after pregnancy, while their results are inconsistent. To increase efficacy of intervention, the multifactorial origins of GDM and the tight link between mental and metabolic as well as maternal and child health need to be heeded. This calls for an interdisciplinary transgenerational approach starting in, but continuing beyond pregnancy. Methods and analysis This randomised controlled trial will assess the effect of a multidimensional interdisciplinary lifestyle and psychosocial intervention aimed at improving the metabolic and mental health of 200 women with GDM and their offspring. Women with GDM at 24–32 weeks gestational age who understand French or English, and their offspring and partners can participate. The intervention components will be delivered on top of usual care during pregnancy and the first year postpartum. Metabolic and mental health outcomes will be measured at 24–32 weeks of pregnancy, shortly after birth and at 6–8 weeks and 1 year after childbirth. Data will be analysed using intention-to-treat analyses. The MySweetHeart Trial is linked to the MySweetHeart Cohort (clinicaltrials.gov/ct2/show/NCT02872974). Ethics and dissemination We will disseminate the findings through regional, national and international conferences and through peer-reviewed journals. Trial registration number NCT02890693; Pre-results.

Acute post-exercise oxygen uptake, hormone and plasma metabolite response in obese men.

This study aimed to compare oxygen uptake (  VO2), hormone and plasma metabolite responses during the 30 min after submaximal incremental exercise (Incr) performed at the same relative/absolute exercise intensity and duration in lean (L) and obese (O) men. Eight L and 8 O men (BMI: 22.9 ± 0.4; 37.2 ± 1.8 kg · m(-2)) completed Incr and were then seated for 30 min.   VO2 was monitored during the first 10 min and from the 25-30(th) minutes of recovery. Blood samples were drawn for the determination of hormone (catecholamines, insulin) and plasma metabolite (NEFA, glycerol) concentrations. Excess post-exercise oxygen consumption (EPOC) magnitude during the first 10 min was similar in O and in L (3.5 ± 0.4; 3.4 ± 0.3 liters, respectively, p=0.86). When normalized to percent change (  VO2END=100%), %   VO2END during recovery was significantly higher from 90-120 s in O than in L (p ≤ 0.04). There were no significant differences in catecholamines (p ≥ 0.24), whereas insulin was significantly higher in O than in L during recovery (p=0.01). The time-course of glycerol was similar from 10-30 min of recovery (-42% for L; -41% for O, p=0.85), whereas significantly different patterns of NEFA were found from 10-30 min of recovery between groups (-18% for L; +8% for O, p=0.03). Despite similar EPOC, a difference in   VO2 modulation between groups was observed, likely due to faster initial rates of   VO2 decline in L than in O. The different patterns of NEFA between groups may suggest a lower NEFA reesterification during recovery in O, which was not involved in the rapid EPOC component.