Evaluación de los efectos de un dispositivo de entrenamiento de los músculos inspiratorios sobre la oxigenación muscular y la activación neuromuscular de los músculos respiratorios / [Evaluation of the effects of an inspiratory muscle training device on muscle oxygenation and neuromuscular activation of the respiratory muscles]

Objetivo: Comparar los cambios en la actividad electromiográfica y oxigenación muscular periférica de los músculos intercostales, en su condición de musculatura accesoria a la respiración, en pacientes con EPOC durante la realización de un test de marcha de 6 minutos (TM6M) con y sin el uso de un dispositivo FeelBreathe (FB).Material y métodos: Se seleccionaron a 20 sujetos diagnosticados de EPOC a los que se les realizaron dos TM6M separados al menos por 60 minutos. Aleatoriamente, cada uno de los pacientes realizó dos TM6M, uno usando el dispositivo FB y el otro sin FB (SFB) y se midieron durante la realización de ambos TM6M la actividad electromiográfica (EMG) obteniéndose la raíz de la media cuadrática (RMS), y por otro lado la oxigenación tisular de los músculos intercostales a través de la variable de oxihemoglobina (HbO2).Resultados: No hubo diferencias significativas en la distancia recorrida en ambos TM6M con FC a SFB. Tanto la RMS como la oxigenación tisular mostraron valores similares entre la condición FB vs. SFB al final de ambas pruebas (32,26 ± 101,94 μV vs 28,25 ± 87,02 μV; p = 0,16 y 70,63 ± 18,80 vs 70,74 ± 16,77; p = 0,975 respectivamente).Conclusiones: El estímulo de trabajo de la musculatura intercostal durante el TM6M con el dispositivo FB no compromete la aparición de la fatiga temprana por un exceso de activación o disminución de la oxigenación de dichos músculos al nivel de intensidad del TM6M. (AU)

Objective: To compare changes in electromyographic activity and peripheral muscle oxygenation of the intercostal muscles, in their condition as accessory muscles for respiration, in patients with COPD during a 6-minute walk test (6MWT) with and without the use of a FeelBreathe (FB) device.Material and methods: 20 subjects diagnosed with COPD who underwent two 6MTMs separated by at least 60 minutes were selected. Randomly, each of the patients underwent two 6MWT, one using the FB device and the other without FB (SFB) and electromyographic activity (EMG) was measured during the performance of both 6MWT, obtaining the root mean square (RMS), and on the other hand, tissue oxygenation of the intercostal muscles through the oxyhemoglobin (HbO2) variable.Results: There were no significant differences in the distance traveled in both 6MWT with HR to SFB. Both RMS and tissue oxygenation showed similar values between the FB condition vs. SFB at the end of both tests (32.26 ± 101.94 μV vs 28.25 ± 87.02 μV; p = 0.16 and 70.63 ± 18.80 vs 70.74 ± 16.77; p = 0.975 respectively).Conclusions: The work stimulus of the intercostal muscles during the 6MWT with the FB device does not compromise the appearance of early fatigue due to excessive activation or decreased oxygenation of these muscles at the intensity level of the 6MWT. (AU)

Sun Protection Habits and Sunburn in Elite Aquatics Athletes: Surfers, Windsurfers and Olympic Sailors.

The objective of this study was to analyse the sun exposure habits of elite aquatics athletes, together with their sunburn history and skin examination habits, taking into account differences by sex and between sports. A cross-sectional health survey was conducted at world championship events during which elite surfers, windsurfers and Olympic sailors from 30 different countries were invited to participate. The athletes were asked to complete a self-administered questionnaire focused on sun protection habits, sun exposure and sports practices. The survey was completed by 240 athletes, 171 men (71.3%) and 69 women (28.8%), with a mean age of 22 years (SD 5.86) and skin phototypes I (6.3%), II (3.3%), III (22.0%), IV (32.5%), V (9.2%) and VI (1.7%). There were significant differences between male and female athletes in skin self-examination (p < 0.001) and in the use of sunglasses (p < 0.001). In sunburn history during the last season, there were significant differences (p < 0.001) among the three sports analysed, in both sexes. The mean rate of sunburn during the previous season was 76.7%, and 27.5% of participants reported having experienced three or more sunburns that lasted at least 1 day. This type of athlete is at high risk of sunburn and hence of future skin cancer. However, there is a general lack of awareness of this risk. This study highlights the need to inform such athletes and to raise awareness of the dangers, through educational interventions on the importance of protecting against sunburn in order to reduce the future incidence of skin cancer.

Androgen receptor gene polymorphism influence fat accumulation: A longitudinal study from adolescence to adult age.

To determine the influence of androgen receptor CAG and GGN repeat polymorphisms on fat mass and maximal fat oxidation (MFO), CAG and GGN repeat lengths were measured in 128 young boys, from which longitudinal data were obtained in 45 of them [mean ± SD: 12.8 ± 3.6 years old at recruitment, and 27.0 ± 4.8 years old at adult age]. Subjects were grouped as CAG short (CAGS ) if harboring repeat lengths ≤ 21, the rest as CAG long (CAGL ); and GGN short (GGNS ) if GGN repeat lengths ≤ 23, or long if > 23 (GGNL ). CAGS and GGNS were associated with lower adiposity than CAGL or GGNL (P < 0.05). There was an association between the logarithm of CAG repeats polymorphism and the changes of body mass (r = 0.34, P = 0.03). At adult age, CAGS men showed lower accumulation of total body and trunk fat mass, and lower resting metabolic rate (RMR) and MFO per kg of total lean mass compared with CAGL (P < 0.05). GGNS men also showed lower percentage of body fat (P < 0.05). In summary, androgen receptor CAG and GGN repeat polymorphisms are associated with RMR, MFO, fat mass, and its regional distribution in healthy male adolescents, influencing fat accumulation from adolescence to adult age.

A time-efficient reduction of fat mass in 4 days with exercise and caloric restriction.

To determine whether a fast reduction in fat mass can be achieved in 4 days by combining caloric restriction (CR: 3.2 kcal/kg body weight per day) with exercise (8-h walking + 45-min arm cranking per day) to induce an energy deficit of ∼5000 kcal/day, 15 overweight men underwent five experimental phases: pretest, exercise + CR for 4 days (WCR), control diet + reduced exercise for 3 days (DIET), and follow-up 4 weeks (POST1) and 1 year later (POST2). During WCR, the diet consisted solely of whey protein (n = 8) or sucrose (n = 7) (0.8 g/kg body weight per day). After WCR, DIET, POST1, and POST2, fat mass was reduced by a mean of 2.1, 2.8, 3.8, and 1.9 kg (P < 0.05), with two thirds of this loss from the trunk; and lean mass by 2.8, 1.0, 0.5, and 0.4 kg, respectively. After WCR, serum glucose, insulin, homeostatic model assessment, total and low-density lipoprotein cholesterol and triglycerides were reduced, and free fatty acid and cortisol increased. Serum leptin was reduced by 64%, 50%, and 33% following WCR, DIET, and POST1, respectively (P < 0.05). The effects were similar in both groups. In conclusion, a clinically relevant reduction in fat mass can be achieved in overweight men in just 4 days by combining prolonged exercise with CR.

A reliable unipedal stance test for the assessment of balance using a force platform.

BACKGROUND: The aim was to develop a unipedal stance test for the assessment of balance using a force platform. METHODS: A single-leg balance test was conducted in 23 students (mean ± SD) age: 23 ± 3 years) in a standard position limiting the movement of the arms and non-supporting leg. Six attempts, with both the jumping (JL) and the contralateral leg (CL), were performed under 3 conditions: 1) eyes opened; 2) eyes closed; 3) eyes opened and executing a precision task. The same protocol was repeated two-week apart. RESULTS: The mean and the best result of the six attempts performed each day were taken as representative of balance. The speed of the centre of pressure (CP-Speed) showed excellent reliability for the "best result" analysis in all tests (ICCs 0.87-0.97), except in the test with the eyes closed performed on the CL (ICC<0.4). The CP-Speed had better reliability with the "best result" than with the "mean result" analysis (P<0.05), whilst no significant differences were observed between the JL and the CL (P=0.71 and P=0.96 for mean and best results analysis, respectively). A lower dispersion in the Bland and Altman graph was observed with the eyes opened than closed, and the dynamic test. CONCLUSION: The single-leg stance balance test proposed is a reliable method to assess balance, especially when performed in a static position, with the eyes opened and using the best result of six attempts as reference, independently of the stance leg.

Isoinertial and isokinetic sprints: muscle signalling.

To determine if the muscle signalling response to a 30 s all-out sprint exercise is modulated by the exercise mode and the endocrine response, 27 healthy volunteers were divided in 2 groups that performed isokinetic (10 men and 5 women) and isoinertial (7 men and 5 women) Wingate tests. Blood samples and vastus lateralis muscle biopsies were taken before, immediately after, 30 and 120 min after the sprints. Groups were comparable in age, height, body weight, percentage of body fat, peak power per kg of lower extremities lean mass (Pmax) and muscle fibre types. However, the isoinertial group achieved a 25% greater mean power (Pmean). Sprint exercise elicited marked increases in the musculus vastus lateralis AMPKα, ACCß, STAT3, STAT5 and ERK1/2 phosphorylation (all P<0.05). The AMPKα, STAT3, and ERK1/2 phosphorylation responses were more marked after the isoinertial than isokinetic test (interaction: P<0.01). The differences in muscle signalling could not be accounted for by differences in Pmax, although Pmean could explain part of the difference in AMPKα phosphorylation. The leptin, insulin, glucose, GH, IL-6, and lactate response were similar in both groups. In conclusion, the muscle signalling response to sprint exercise differs between isoinertial and isokinetic sprints.

Normal mitochondrial function and increased fat oxidation capacity in leg and arm muscles in obese humans.

AIM/HYPOTHESIS: The aim of this study was to investigate mitochondrial function, fibre-type distribution and substrate oxidation during exercise in arm and leg muscles in male postobese (PO), obese (O) and age- and body mass index (BMI)-matched control (C) subjects. The hypothesis of the study was that fat oxidation during exercise might be differentially preserved in leg and arm muscles after weight loss. METHODS: Indirect calorimetry was used to calculate fat and carbohydrate oxidation during both progressive arm-cranking and leg-cycling exercises. Muscle biopsy samples were obtained from musculus deltoideus (m. deltoideus) and m. vastus lateralis muscles. Fibre-type composition, enzyme activity and O(2) flux capacity of saponin-permeabilized muscle fibres were measured, the latter by high-resolution respirometry. RESULTS: During the graded exercise tests, peak fat oxidation during leg cycling and the relative workload at which it occurred (FatMax) were higher in PO and O than in C. During arm cranking, peak fat oxidation was higher in O than in C, and FatMax was higher in O than in PO and C. Similar fibre-type composition was found between groups. Plasma adiponectin was higher in PO than in C and O, and plasma leptin was higher in O than in PO and C. CONCLUSIONS: In O subjects, maximal fat oxidation during exercise and the eliciting relative exercise intensity are increased. This is associated with higher intramuscular triglyceride levels and higher resting non esterified fatty acid (NEFA) concentrations, but not with differences in fibre-type composition, mitochondrial function or muscle enzyme levels compared with Cs. In PO subjects, the changes in fat oxidation are preserved during leg, but not during arm, exercise.