Antioxidant enzymes and Nrf2/Keap1 in human skeletal muscle: Influence of age, sex, adiposity and aerobic fitness.

Ageing, a sedentary lifestyle, and obesity are associated with increased oxidative stress, while regular exercise is associated with an increased antioxidant capacity in trained skeletal muscles. Whether a higher aerobic fitness is associated with increased expression of antioxidant enzymes and their regulatory factors in skeletal muscle remains unknown. Although oestrogens could promote a higher antioxidant capacity in females, it remains unknown whether a sex dimorphism exists in humans regarding the antioxidant capacity of skeletal muscle. Thus, the aim was to determine the protein expression levels of the antioxidant enzymes SOD1, SOD2, catalase and glutathione reductase (GR) and their regulatory factors Nrf2 and Keap1 in 189 volunteers (120 males and 69 females) to establish whether sex differences exist and how age, VO2max and adiposity influence these. For this purpose, vastus lateralis muscle biopsies were obtained in all participants under resting and unstressed conditions. No significant sex differences in Nrf2, Keap1, SOD1, SOD2, catalase and GR protein expression levels were observed after accounting for VO2max, age and adiposity differences. Multiple regression analysis indicates that the VO2max in mL.kg LLM-1.min-1can be predicted from the levels of SOD2, Total Nrf2 and Keap1 (R = 0.58, P < 0.001), with SOD2 being the main predictor explaining 28 % of variance in VO2max, while Nrf2 and Keap1 explained each around 3 % of the variance. SOD1 protein expression increased with ageing in the whole group after accounting for differences in VO2max and body fat percentage. Overweight and obesity were associated with increased pSer40-Nrf2, pSer40-Nrf2/Total Nrf2 ratio and SOD1 protein expression levels after accounting for differences in age and VO2max. Overall, at the population level, higher aerobic fitness is associated with increased basal expression of muscle antioxidant enzymes, which may explain some of the benefits of regular exercise.

Thermal resting pattern and acute skin temperature response to exercise in older adults: Role of cardiorespiratory fitness.

BACKGROUND: Infrared thermography is a growing area of interest in sports science due to the potential of skin temperature (Tsk) measurements to provide valuable information from rest to exercise. However, limited research exists on Tsk in older adults and the impact of factors such as sex and cardiorespiratory fitness (CRF) on Tsk. This study aims to investigate Tsk at rest and after acute exercise in older adults and assess whether sex or CRF influences Tsk. METHODS: Ninety-two participants (41 women, 68.48 ± 3.01 years) were examined with a thermographic camera in a conditioned room (23.02 ± 3.01 °C) at rest and after a graded protocol. The Tsk of 25 regions of interest (ROIs) were extracted and analysed. RESULTS: Men had higher overall Tsk at rest in 76% of ROIs, showing significant differences (p < 0.010) in six specific ROIs, independent of CRF. Both sexes had similar Tsk responses after graded exercise, with increases in distal parts (1.06 ± 0.50 °C), decreases in proximal parts (-0.62 ± 0.42 °C), and stable central Tsk (0.23 ± 0.59 °C). Increases in lower limb Tsk were significantly associated with CRF in men and women (ß = 0.438, p = 0.001, and ß = 0.535, p < 0.001, respectively), explaining 17% and 27% of the variance, respectively. CONCLUSIONS: This study demonstrates a sex-specific effect on resting Tsk in older adults, suggesting that sex-specific Tsk patterns should be considered when analysing Tsk in this population. Additionally, the association between increases in lower limb Tsk and CRF suggests that Tsk could be a promising predictor of CRF in older adults.

Changes in Muscle Deoxygenation During Squat Exercise After 6-Week Resistance Training With Different Percentages of Velocity Loss.

ABSTRACT: Costilla, M, Casals, C, Marín-Galindo, A, Sánchez-Sixto, A, Muñoz-López, A, Sañudo, B, Corral-Pérez, J, and Ponce-González, JG. Changes in muscle deoxygenation during squat exercise after 6-week resistance training with different percentages of velocity loss. J Strength Cond Res 37(8): 1573-1580, 2023-The present study compared, for the first time, the effects of 6 weeks of 20% (20VL) vs. 40% (40VL) velocity loss (VL) resistance training (RT) programs on muscle oxygen dynamics during the squat exercise. Twenty-three young men (21.4 ± 2.4 years) were randomly allocated into the 20VL group ( n = 8), 40VL group ( n = 7), or control group (CG; n = 8). The RT program consisted of 3 sets of Smith machine back squat exercise at 20VL or 40VL with a 3-minute rest between sets, twice per week for 6 weeks. Tissue oxygenation index (TOI) was measured using near-infrared spectroscopy in the vastus medialis and vastus lateralis during a squat test (8-repetition 1 m·s -1 load test), and the maximum (maxTOI) and minimum (minTOI) TOIs were measured during a 3-min recovery period. After the 6-week RT program, TOI increased significantly at the beginning of the test in both muscles (during the first 4 repetitions in the vastus lateralis and 5 repetitions in the vastus medialis) in the 20VL group ( p < 0.05), with nonsignificant changes in the 40VL group and CG. The maxTOI was significantly increased in the vastus medialis (+3.76%) and vastus lateralis (+3.97%) after the training only in the 20VL group ( p < 0.05). The minTOI in the vastus medialis reached during the test remained unchanged postintervention for both training groups, with the CG showing significantly higher values compared with the 20VL group (+14.1%; p < 0.05). In conclusion, depending on the VL reached during a squat RT program, different changes in muscle oxygen dynamics can be expected. Training at 20% of VL improves metabolic efficiency and the reoxygenation peak after the set.

Antioxidants Markers of Professional Soccer Players During the Season and their Relationship with Competitive Performance.

The aim of this study was to assess antioxidant markers before and after a mid-season of professional soccer players from the 3rd Spanish Division, and to correlate antioxidant markers with competitive performance. Sixty-five male players (age = 25.3 ± 4.2 yr, body mass = 73.2 ± 6.7 kg, body height = 177.8 ± 5.7 cm) from three soccer clubs from Cádiz (Spain) participated in the study. Body composition, maximal aerobic capacity (VO2max), and baseline antioxidant blood markers (Total Antioxidant Status (TAS) and Reduced glutathione/Oxidized glutathione ratio) were assessed in the first week of the championship season (pre-test) and after 18 weeks in the mid-season (post-test). Soccer performance was registered according to the official classification ranking at both the mid-season and at the end of the season; ranking positions for Team A were 2nd and 1st, for Team B were 5th and 5th, while for Team C were 12th and 14th, respectively. Regression analyses showed that TAS and VO2max were able to independently predict (p < 0.05) performance in our participants. Moreover, antioxidant levels showed significant main effects on performance (p < 0.001); where a higher antioxidant capacity was observed in the best performance soccer team, both before and after the mid-season. Notwithstanding, the competitive period compromised the antioxidant status since TAS levels significantly decreased after the 18-week training program and competition compared with baseline values in all soccer teams (p < 0.001). These results suggest the need of monitoring antioxidants in soccer players to prevent excessive oxidative stress and cellular damage which could compromise success in competition, by adjusting the training loads, diet or ergogenic aids, if needed.

Angiotensin-Converting Enzyme 2 (SARS-CoV-2 receptor) expression in human skeletal muscle.

The study aimed to determine the levels of skeletal muscle angiotensin-converting enzyme 2 (ACE2, the SARS-CoV-2 receptor) protein expression in men and women and assess whether ACE2 expression in skeletal muscle is associated with cardiorespiratory fitness and adiposity. The level of ACE2 in vastus lateralis muscle biopsies collected in previous studies from 170 men (age: 19-65 years, weight: 56-137 kg, BMI: 23-44) and 69 women (age: 18-55 years, weight: 41-126 kg, BMI: 22-39) was analyzed in duplicate by western blot. VO2 max was determined by ergospirometry and body composition by DXA. ACE2 protein expression was 1.8-fold higher in women than men (p = 0.001, n = 239). This sex difference disappeared after accounting for the percentage of body fat (fat %), VO2 max per kg of legs lean mass (VO2 max-LLM) and age (p = 0.47). Multiple regression analysis showed that the fat % (ß = 0.47) is the main predictor of the variability in ACE2 protein expression in skeletal muscle, explaining 5.2% of the variance. VO2 max-LLM had also predictive value (ß = 0.09). There was a significant fat % by VO2 max-LLM interaction, such that for subjects with low fat %, VO2 max-LLM was positively associated with ACE2 expression while as fat % increased the slope of the positive association between VO2 max-LLM and ACE2 was reduced. In conclusion, women express higher amounts of ACE2 in their skeletal muscles than men. This sexual dimorphism is mainly explained by sex differences in fat % and cardiorespiratory fitness. The percentage of body fat is the main predictor of the variability in ACE2 protein expression in human skeletal muscle.

Maximal fat oxidation capacity is associated with cardiometabolic risk factors in healthy young adults.

It is unknown whether resting fat oxidation (RFO), maximal fat oxidation (MFO) and FatMax (intensity at which MFO is reached) are related to cardiometabolic risk (CMR). Thus the aim of this study was to examine the association of RFO, MFO and FatMax with CMR. 81 healthy adults (n = 31 women; 22.72 ± 4.40 years) participated in this cross-sectional study. Glucose and triglycerides were analysed in plasma. Body composition, anthropometry, physical activity, blood pressure (BP) and heart rate measurements were taken. RFO and MFO were determined through indirect calorimetry. Maximal oxygen uptake (VO2max) test was performed until exhaustion after MFO test. The CMR cluster was created from individual CMR factors: waist circumference, body fat percentage, systolic BP, diastolic BP, blood glucose and plasma triglycerides. Groups of high and low MFO and VO2max were created. RFO was not associated with CMR (p < 0.05). FatMax, MFO and VO2max were associated with individual CMR factors as waist circumference (R2 = 0.144; R2 = 0.241; R2 = 0.285; p = 0.001; respectively) and plasma triglycerides (R2 = 0.111; p = 0.004 and R2 = 0.130; p = 0.002 and R2 = 0.093; p = 0.008; respectively) and clustered CMR factors (R2 = 0.105; p = 0.008 and R2 = 0.162; p = 0.001 and R2 = 0.239; p = 0.001; respectively). VO2max was also associated with body fat percentage (R2 = 0.105; p = 0.003) and diastolic BP (R2 = 0.083; p = 0.01), even adjusting for sex or age (p < 0.05). Groups with high level of MFO or VO2max obtained lower CMR (p = 0.001), even adjusting for sex or age (p < 0.01). FatMax, MFO and, especially, VO2max are associated with CMR, regardless of age and sex. However, RFO is not associated with CMR.

Impact of Active Recovery and Whole-Body Electromyostimulation on Blood-Flow and Blood Lactate Removal in Healthy People.

This study aimed to determine whether an active recovery with added whole-body electromyostimulation (WB-EMS) can increase blood flow and lead to blood lactate removal after intense exercise. Thirty-five healthy individuals (23.1 ± 4.6 years) were randomly assigned to: (a) an experimental group using active recovery together with the WB-EMS (n = 18) or (b) a control group using the same active recovery protocol with the suit with no-stimulation (CON, n = 17). Participants performed a maximal graded exercise test followed by an active recovery protocol (walking at 40% of their maximum aerobic velocity). During the recovery, participants in WB-EMS and CON received continuous stimulation at 7 Hz or no stimulation, respectively. Heart rate, blood lactate concentrations, pain/discomfort, and hemodynamic measurements were recorded before and after the test, and repeated immediately after and at min 30 and 60. The between-group analysis showed a substantially greater Peak blood velocity (-0.27 [-0.68; 0.14]) in WB-EMS compared to CON. The pain/discomfort levels were also lower in WB-EMS compared with CON (0.66 [-0.12; 1.45]). Non-significant differences in participants' blood lactate were observed in WB-EMS compared with CON both immediately; at 30and 60 min. Our findings suggest that increased local blood flow induced by WB-EMS may have contributed to greater lactate removal from active muscles and blood lactate clearance. WB-EMS may be an effective means of increasing muscle blood flow after a maximal graded exercise test and could result in improved recovery.

The Federated Practice of Soccer Influences Hamstring Flexibility in Healthy Adolescents: Role of Age and Weight Status.

The aim of this study was to compare the hamstring flexibility between federated soccer and non-federated adolescents, and also to evaluate the effect of age and weight status on hamstring flexibility. The participants were 234 students (11-18 years old) divided into: (i) G1: non-federated (n = 127), and (ii) G2: federated in soccer (n = 107). The deep flexion of the trunk (DF) test and the sit and reach test (SRT) were performed. G2 showed higher values for the DF and SRT compared to G1 (p < 0.05). Both flexibility tests correlated positively (r = 0.4, p < 0.001). Body mass index (BMI) was negatively correlated with the DF test (r = -0.3, p < 0.001), but not with the SRT. Divided by BMI, the underweight and normal weight groups had higher scores in the DF test compared with the overweight and obese groups (p < 0.001). BMI was negatively correlated with hamstring flexibility. Federated soccer students present higher scores of hamstring flexibility.

Aerobic fitness, Mediterranean diet and cardiometabolic risk factors in adults. / Capacidad aeróbica, dieta mediterránea y riesgo cardiometabólico en adultos.

INTRODUCTION: Unhealthy lifestyle and inadequate diet could influence the development of future cardiometabolic disease. The main aim of this study was to determine the association between aerobic fitness and cardiometabolic risk factors in adults, whether this relation is depends of adherence to Mediterranean diet (MD). A secondary aim was to study the combined effect of aerobic capacity and adherence to MD on global cardiometabolic risk score (CMRS). METHOD: A total of 79 adults (38% women) enrolled between 18-40 year from Cádiz. We measured adiposity indicators, blood pressure, triglycerides, glucose and inflammatory profile (interleukin-6 and tumor necrosis factor) and was computed (CMRS). Aerobic fitness was measured by maximal oxygen comsuption through an incremental stress test by cycleergometer. The MD patterns was measured using the questionnaire of adherence to MD. The association between aerobic fitness and cardiometabolic risk factors was examined using a lineal regression and it was adjusted for different confounders. CMRS on the lifestyle was analyzed using the ANOVA test, with statistical significance level of P<0.05 in Bonferroni. RESULTS: Linear regression showed inverse association between aerobic fitness and cardiometabolic risk factors (all P≤0.05) in the model without adjustment. Blood pressure and triglycerides lost the association after adjust model for sex, age, and adherence to MD. Participants with high aerobic fitness and high adherence to MD show a lowest CMRS (-1.083±2.325 vs. 2.802±1.759). CONCLUSIONS: Aerobic fitness was inversely associated with fatness risk factors, that relationship is independent to adherence to MD. A high adherence to MD could modulate blood pressure. A combination of high aerobic capacity and high adherence to MD could reduce the adverse consecuence of a low adherencie to MD.

Impact of data averaging strategies on V̇O2max assessment: Mathematical modeling and reliability.

BACKGROUND: No consensus exists on how to average data to optimize V ˙ O2max assessment. Although the V ˙ O2max value is reduced with larger averaging blocks, no mathematical procedure is available to account for the effect of the length of the averaging block on V ˙ O2max. AIMS: To determine the effect that the number of breaths or seconds included in the averaging block has on the V ˙ O2max value and its reproducibility and to develop correction equations to standardize V ˙ O2max values obtained with different averaging strategies. METHODS: Eighty-four subjects performed duplicate incremental tests to exhaustion (IE) in the cycle ergometer and/or treadmill using two metabolic carts (Vyntus and Vmax N29). Rolling breath averages and fixed time averages were calculated from breath-by-breath data from 6 to 60 breaths or seconds. RESULTS: V ˙ O2max decayed from 6 to 60 breath averages by 10% in low fit ( V ˙ O2max  < 40 mL kg-1  min-1 ) and 6.7% in trained subjects. The V ˙ O2max averaged from a similar number of breaths or seconds was highly concordant (CCC > 0.97). There was a linear-log relationship between the number of breaths or seconds in the averaging block and V ˙ O2max (R2  > 0.99, P < 0.001), and specific equations were developed to standardize V ˙ O2max values to a fixed number of breaths or seconds. Reproducibility was higher in trained than low-fit subjects and not influenced by the averaging strategy, exercise mode, maximal respiratory rate, or IE protocol. CONCLUSIONS: The V ˙ O2max decreases following a linear-log function with the number of breaths or seconds included in the averaging block and can be corrected with specific equations as those developed here.

Protein synthesis signaling in skeletal muscle is refractory to whey protein ingestion during a severe energy deficit evoked by prolonged exercise and caloric restriction.

BACKGROUND: Exercise and protein ingestion preserve muscle mass during moderate energy deficits. OBJECTIVE: To determine the molecular mechanisms by which exercise and protein ingestion may spare muscle mass during severe energy deficit (5500 kcal/day). DESIGN: Fifteen overweight, but otherwise healthy men, underwent a pre-test (PRE), caloric restriction (3.2 kcals/kg body weight/day) + exercise (45 min one-arm cranking + 8 h walking) for 4 days (CRE), followed by a control diet (CD) for 3 days, with a caloric content similar to pre-intervention while exercise was reduced to less than 10,000 steps per day. During CRE, participants ingested either whey protein (PRO, n = 8) or sucrose (SU, n = 7) (0.8 g/kg body weight/day). Muscle biopsies were obtained from the trained and untrained deltoid, and vastus lateralis. RESULTS: Following CRE and CD, serum concentrations of leptin, insulin, and testosterone were reduced, whereas cortisol and the catabolic index (cortisol/total testosterone) increased. The Akt/mTor/p70S6K pathway and total eIF2α were unchanged, while total 4E-BP1 and Thr37/464E-BP1 were higher. After CRE, plasma BCAA and EAA were elevated, with a greater response in PRO group, and total GSK3ß, pSer9GSK3ß, pSer51eIF2α, and pSer51eIF2α/total eIF2α were reduced, with a greater response of pSer9GSK3ß in the PRO group. The changes in signaling were associated with the changes in leptin, insulin, amino acids, cortisol, cortisol/total testosterone, and lean mass. CONCLUSIONS: During severe energy deficit, pSer9GSK3ß levels are reduced and human skeletal muscle becomes refractory to the anabolic effects of whey protein ingestion, regardless of contractile activity. These effects are associated with the changes in lean mass and serum insulin, testosterone, and cortisol concentrations.

Anthropometry and performance of top youth international male basketball players in Spanish national academy.

The "Century XXI" Project is a seven-year intervention sport program performed among the best Spanish youth basketball players, who were assigned to one of the following intervention groups based on the following criteria: age, position, mature level, and origin in the country. The study was performed (1996-2001) with a total of 90 players. The main purposes of this study were: a) to describe anthropometric and performance characteristics of top youth international male basketballers in the Spanish national academy; and b) to analyze differences among positions. Insummary, the main findings of this study were: a) the anthropometry presented significant differences between groups under (U-) 14 and U-17; and b) in the U-17 group centers presented more arm span. In our study, the most significant changes are in U-16 vs U-14 and U-15 in strength body up values, and the best result in endurance capacity took place in June of the fourth year. Within this context, the results of the present study may be useful for strength and conditioning coaches to plan their programs with youth basketball players.

Fitness and academic performance in adolescents. The mediating role of leptin: DADOS study.

We tested the mediating effect of leptin on the association between physical fitness (PF) components and academic performance indicators in healthy adolescents. A total of 263 adolescents (13.9 ± 0.3 years, 47.5% girls, 12.5% overweight) from the DADOS (Deporte, ADOlescencia y Salud) Study were included in the analysis. PF components were assessed by the handgrip test for upper-limb muscular strength, standing long jump test for lower-limb muscular strength, 4 × 10-m shuttle run test for speed-agility, and 20-m shuttle run test for cardiorespiratory fitness. Plasma leptin concentration was assessed from antecubital vein blood after an overnight fast using a sensitive ELISA kit. Academic performance indicators were assessed through final school grades and through the Spanish version of the SRA Test of Educational Ability. Body composition was assessed by body mass index and skinfold thicknesses. Boot-strapped mediation procedures were performed and indirect effects with confidence intervals not including zero were interpreted as statistically significant. Our findings suggest that the positive associations observed between cardiorespiratory fitness and lower-limb muscular strength with academic performance indicators were mediated by leptin concentration after adjusting for sex, pubertal stage, socioeconomic status, and adiposity (percentage of mediation ranging from 54.61 to 82.02%). CONCLUSIONS: Improvements on PF components, particularly in cardiorespiratory fitness and lower-limb muscular strength, might reduce leptin concentration with potential benefits on academic performance in adolescents, independently of adiposity. What is Known: • Academic performance is associated with physical fitness and leptin concentration in children and adolescents. • Fitness modulates leptin concentration levels, regardless of physical activity and adiposity. What is New: • Leptin concentration mediates the association of cardiorespiratory fitness and muscular strength with academic performance in adolescents. • Improvements in cardiorespiratory fitness and muscular strength might reduce leptin concentration levels enhancing academic performance.

Teachers' knowledge about type 1 diabetes in south of Spain public schools.

AIMS: To evaluate the knowledge of teachers in educative public centres (pre-, primary, and secondary schools) about type 1 diabetes (T1D) in the Puerto Real University Hospital area (Cadiz, Spain). METHODS: Descriptive observational study in which 756 teachers' answers on the Test of Diabetes Knowledge for Teachers (TDKT) were analysed. Teachers from 44 educative public centres in the Puerto Real University Hospital area (Cadiz, Spain) were selected by randomized sampling (mean age, 44.3 ±â€¯8 years; 61.7% women). RESULTS: Although 43.2% survey respondents recognised having had or currently having children or adolescent students with T1D, most demonstrated they did not have enough knowledge about T1D (mean score, 6.0 ±â€¯4.3 points from a maximum of 16), and only 5.1% had sufficient knowledge (13-16 points) to be an effective support person to students with diabetes in school. However, the vast majority of survey respondents correctly answered questions about symptoms (74.2%) and hypoglycaemia treatment (85.9%). Univariate analysis of factors associated with teachers' knowledge about diabetes revealed that teachers with ≤ 15 years of teaching experience and physical education teachers had better knowledge than their co-workers. CONCLUSIONS: It is necessary to improve teachers' knowledge about diabetes in our health area with the aim of improving the security of children and adolescent students with T1D in school centres.

Teachers' attitudes and perceptions about preparation of public schools to assist students with type 1 diabetes. / Actitudes y percepción del profesorado de centros educativos públicos sobre la atención a alumnos con diabetes tipo 1.

OBJECTIVE: To assess teachers' attitudes and perceptions about preparation of public primary and secondary education schools in the Puerto Real University Hospital (Cádiz, Spain) area to care for students with type 1 diabetes mellitus (T1DM) METHODS: A descriptive observational study where answers to an attitude and perception questionnaire on the preparation of schools to care for pupils with T1DM were analyzed. A total of 765 teachers (mean age, 44.3±8.8 years; 61.7% women) from 44 public schools in the area of the Puerto Real University Hospital were selected by random sampling. RESULTS: Overall, 43.2% of teachers surveyed had or had previously had students with T1DM, but only 0.8% had received specific training on diabetes. 18.9% of teachers reported that one of their students with T1DM had experienced at least one episode of hypoglycemia at school, and half of them felt that their school was not prepared to deal with diabetic emergencies. 6.4% stated that their school had glucagon in its first aid kit, and 46.9% would be willing to administer it personally. Women, physical education teachers, and headmasters had a more positive perception of the school than their colleagues. Teachers with a positive perception of school preparation and with a positive attitude to administer glucagon were significantly younger than those with no positive perception and attitude. CONCLUSIONS: The study results suggest that teachers of public schools in our health area have not been specifically trained in the care of patients with T1DM and perceive that their educational centers are not qualified to address diabetic emergencies.

Androgen receptor gene polymorphisms and maximal fat oxidation in healthy men. A longitudinal study.

INTRODUCTION: Androgens play a major role in fat oxidation; however, the effects of androgens depend, among other factors, on the intrinsic characteristics of the androgen receptor (AR). Lower repetitions of CAG and GGN polymorphism appear to have a protective effect on fat accumulation in the transition from adolescent to mid-twenties. Whether a similar protective effect is present later in life remains unknown. The aims of this study were: a) to evaluate if extreme CAG and GGN repeat polymorphisms of the androgen receptors influence body fat mass, its regional distribution, resting metabolic rate (RMR), maximal fat oxidation capacity (MFO) and serum leptin, free testosterone and osteocalcin in healthy adult men; and b) to determine the longitudinal effects on fat tissue accumulation after 6.4 years of follow-up. METHODS: CAG and GGN repeats length were measured in 319 healthy men (mean ± standard deviation [SD]: 28.3 ± 7.6 years). From these, we selected the subjects with extreme short (CAGS < or equal 19; n = 7) and long (CAGL > or equal 24; n = 10) CAG repeats, and the subjects with short (GGNS < or equal to 22; n = 9) and long (GGNL > or equal to 25; n = 10) GGN repeats. Body composition was assessed by DXA and serum levels of leptin, free testosterone and osteocalcin by ELISA. After 6.4 years of follow-up, DXA was repeated, and resting metabolic rate (RMR), MFO and VO2max determined by indirect calorimetry. RESULTS: CAGS and CAGL subjects had similar RMR and accumulated comparable amounts of fat tissue over 6.4 ± 1.0 years of follow-up. However, CAGL had higher MFO and total lean mass than CAGS (p < 0.05). Men with GGNS accumulated greater amount of total fat mass than men with GGNL, particularly in the trunk region seven years later. This concurred with a greater MFO in the GGNL group (p < 0.05), who accumulated less fat mass. Free testosterone was associated with MFO in absolute values (r = 0.45; p < 0.05) and MFO per kg of lower extremity lean mass per height squared (r = 0.35; p < 0.05). CONCLUSIONES: CAG and GGN repeat polymorphisms may influence muscle fat oxidation capacity and may have a role in the accumulation of fat over the years.

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.

Skeletal muscle signaling, metabolism, and performance during sprint exercise in severe acute hypoxia after the ingestion of antioxidants.

The aim of this study was to determine if reactive oxygen species (ROS) could play a role in blunting Thr172-AMP-activated protein kinase (AMPK)-α phosphorylation in human skeletal muscle after sprint exercise in hypoxia and to elucidate the potential signaling mechanisms responsible for this response. Nine volunteers performed a single 30-s sprint (Wingate test) in two occasions while breathing hypoxic gas ([Formula: see text] = 75 mmHg): one after the ingestion of placebo and another following the intake of antioxidants (α-lipoic acid, vitamin C, and vitamin E), with a randomized double-blind design. Vastus lateralis muscle biopsies were obtained before, immediately after, and 30- and 120-min postsprint. Compared with the control condition, the ingestion of antioxidants resulted in lower plasma carbonylated proteins, attenuated elevation of the AMP-to-ATP molar ratio, and reduced glycolytic rate (P < 0.05) without significant effects on performance or V̇o2 The ingestion of antioxidants did not alter the basal muscle signaling. Thr172-AMPKα and Thr184/187-transforming growth factor-ß-activated kinase 1 (TAK1) phosphorylation were not increased after the sprint regardless of the ingestion of antioxidants. Thr286-CaMKII phosphorylation was increased after the sprint, but this response was blunted by the antioxidants. Ser485-AMPKα1/Ser491-AMPKα2 phosphorylation increased immediately after the sprints coincident with increased Akt phosphorylation. In summary, antioxidants attenuate the glycolytic response to sprint exercise in severe acute hypoxia and modify the muscle signaling response to exercise. Ser485-AMPKα1/Ser491-AMPKα2 phosphorylation, a known mechanism of Thr172-AMPKα phosphorylation inhibition, is increased immediately after sprint exercise in hypoxia, probably by a mechanism independent of ROS.NEW & NOTEWORTHY The glycolytic rate is increased during sprint exercise in severe acute hypoxia. This study showed that the ingestion of antioxidants before sprint exercise in severe acute hypoxia reduced the glycolytic rate and attenuated the increases of the AMP-to-ATP and the reduction of the NAD+-to-NADH.H+ ratios. This resulted in a modified muscle signaling response with a blunted Thr286-CaMKII but similar AMP-activated protein kinase phosphorylation responses in the sprints preceded by the ingestion of antioxidants.

Severe energy deficit upregulates leptin receptors, leptin signaling, and PTP1B in human skeletal muscle.

In obesity, leptin receptors (OBR) and leptin signaling in skeletal muscle are downregulated. To determine whether OBR and leptin signaling are upregulated with a severe energy deficit, 15 overweight men were assessed before the intervention (PRE), after 4 days of caloric restriction (3.2 kcal·kg body wt-1·day-1) in combination with prolonged exercise (CRE; 8 h walking + 45 min single-arm cranking/day) to induce an energy deficit of ~5,500 kcal/day, and following 3 days of control diet (isoenergetic) and reduced exercise (CD). During CRE, the diet consisted solely of whey protein (n = 8) or sucrose (n = 7; 0.8 g·kg body wt-1·day-1). Muscle biopsies were obtained from the exercised and the nonexercised deltoid muscles and from the vastus lateralis. From PRE to CRE, serum glucose, insulin, and leptin were reduced. OBR expression was augmented in all examined muscles associated with increased maximal fat oxidation. Compared with PRE, after CD, phospho-Tyr1141OBR, phospho-Tyr985OBR, JAK2, and phospho-Tyr1007/1008JAK2 protein expression were increased in all muscles, whereas STAT3 and phospho-Tyr705STAT3 were increased only in the arms. The expression of protein tyrosine phosphatase 1B (PTP1B) in skeletal muscle was increased by 18 and 45% after CRE and CD, respectively (P < 0.05). Suppressor of cytokine signaling 3 (SOCS3) tended to increase in the legs and decrease in the arm muscles (ANOVA interaction: P < 0.05). Myosin heavy chain I isoform was associated with OBR protein expression (r = -0.75), phospho-Tyr985OBR (r = 0.88), and phospho-Tyr705STAT3/STAT3 (r = 0.74). In summary, despite increased PTP1B expression, skeletal muscle OBR and signaling are upregulated by a severe energy deficit with greater response in the arm than in the legs likely due to SOCS3 upregulation in the leg muscles.NEW & NOTEWORTHY This study shows that the skeletal muscle leptin receptors and their corresponding signaling cascade are upregulated in response to a severe energy deficit, contributing to increase maximal fat oxidation. The responses are more prominent in the arm muscles than in the legs but partly blunted by whey protein ingestion and high volume of exercise. This occurs despite an increase of protein tyrosine phosphatase 1B protein expression, a known inhibitor of insulin and leptin signaling.

[Not Available].

Introducción y objetivos: un dispositivo llamado FeelBreathe ® (FB) se ha diseñado, desarrollado y patentado para el entrenamiento de la musculatura inspiratoria (IMT). Para examinar los efectos de FB en la ventilación pulmonar y el intercambio gaseoso durante el ejercicio, se tomaron medidas de 27 voluntarios varones sanos entrenados (edad: 32,5 ± 7,2 años). Métodos: al inicio del estudio se midieron tanto la presión inspiratoria máxima estática (PIM) y la capacidad pulmonar mediante espirometría. Seguidamente, se realizó un test incremental en cicloergómetro para determinar el VO 2 pico. Cada sujeto, tres días más tarde, realizó aleatoriamente tres pruebas idénticas submáximas en cicloergómetro a una intensidad comprendida al 50% entre los umbrales ventilatorios bajo tres condiciones de respiración diferentes: a) respiración oronasal (ONB), b) respiración nasal (NB) y c) la respiración nasal a través del FB. Resultados: la prueba con FB mostró una ventilación minuto (VE) y una frecuencia respiratoria (BF) inferior que en las pruebas de NB, la cual a su vez tenía menor BF, pero similar VE que ONB (p < 0,001). A pesar de esto, FB obtuvo valores similares de VO 2 , cociente respiratorio (RER), frecuencia cardiaca (HR) y saturación de oxígeno capilar periférica (SpO2) en comparación con NB y ONB. Esto último puede ocurrir debido en parte al aumento del volumen tidal (VT) y el tiempo de expiración (Tex) en FB hasta el mismo nivel que en la prueba de NB, los cuales fueron un 15% y 14% en ambas pruebas, respectivamente, superiores a ONB (p < 0,001). El porcentaje de tiempo de inspiración (Ti/Tot) fue 7% mayor en la prueba de FB en comparación con NB y ONB (p < 0,001). Solamente en la prueba de FB se encontró un aumento de la presión final de la espiración de CO 2 (P ET CO 2 ) y la reducción de la presión final de la espiración de O 2 (P ET O 2 ) y la fracción de expiración de O 2 (FEO 2 ). Conclusiones: FeelBreathe es un nuevo dispositivo de restricción nasal que estimula los músculos inspiratorios para producir un patrón de respiración más eficiente durante el ejercicio en los seres humanos bien entrenados.