Strenuous exercise in warm environment is associated with improved microvascular function in sickle cell trait.

PURPOSE: Sickle cell trait is characterized by the presence of both normal and abnormal haemoglobin in red blood cells. The rate of exertional collapse is increased in athletes and military recruits who carry the trait, particularly in stressful environmental conditions. The aim of the present study was to investigate microvascular function and its determinants in response to intense exercise at control and warm environmental temperatures in carriers (AS) and non-carriers (AA) of sickle cell trait. METHODS: Nine AS and 11 AA, all healthy physically active young men, randomly participated in four experimental sessions (rest at 21 °C and 31 °C and cycling at 21 °C and 31 °C). All participants performed three exercises bouts as follows: 18-min submaximal exercise; an incremental test to exhaustion; and three 30-s sprints spaced with 20-s resting intervals. RESULTS: Skin Blood Flow (SkBF) was similar at rest between AA and AS. SkBF for all participants was higher at 31 °C than 21 °C. It was significantly higher in the AS group compared to the AA group immediately after exercise, regardless of the environmental conditions. No significant differences in hemorheological parameters, muscle damage or cardiac injury biomarkers were observed between the two groups. Our data also suggest higher oxidative stress for the AS group, with high superoxide dismutase (P = 0.044 main group effect). CONCLUSION: A specific profile is identified in the AS population, with increased microvascular reactivity after maximal exercise in stressful environment and slight pro-/antioxidant imbalance.

Effect of warm environment on the skin blood flow response to food intake.

BACKGROUND AND OBJECTIVE: Warm exposure places high demands on thermoregulation mechanisms, which depend on the effectiveness of the microvascular function. The associations between the microcirculation and metabolism in warm environments have received little attention. The purpose of this study was to explore skin blood flow (SkBF) in response to food intake in a warm environment compared to control. METHODS: Thirty-two healthy, acclimated-to-warm-environment and physically active participants were recruited (20 females and 12 males). They participated in two sessions (warm environment: 31 °C and control: 20 °C, presented in randomized order). SkBF was measured before and after standardized food intake through the acquisition of perfusion signals by laser Doppler flowmetry (Periflux System 5000), following a local heating protocol. RESULTS: SkBF was affected by the environmental temperature, showing an increase in the warm environment compared to control (all p < .001). SkBF was significantly affected by food intake (all p < .007), being reduced after meals. In the men's group, SkBF was reduced in both environmental temperatures after meals. In women, meals affected SkBF at 20 °C but not in the warm environment. CONCLUSION: These results may indicate a competition between thermo- and glyco-regulation in a warm environment to the detriment of glucose homeostasis in women.

Intake of Nutritional Supplements among People Exercising in Gyms in Beirut City.

The use of nutritional supplements among exercisers in gyms has been never investigated in the Middle East. The aim of the current study was to assess the prevalence intake of nutritional supplements and the potential influencing factors among people exercising in gyms in Beirut city. In this cross-sectional study, 512 exercisers, aged between 20 and 50 years, were randomly selected from gyms. The intake of nutritional supplements was reported among 36.3% (95% confidence interval 32.2-40.5) of participants, with a weak presence of medical supervision. Patterns of supplement use differed by gender and age. Men and younger exercisers were found to focus on supplements associated with performance enhancement and muscle building, while women and older exercisers were more concerned with health-promoting products such as vitamins, minerals, and herbal supplements. An appropriate dissemination of accurate and scientifically sound information regarding the benefits and side effects of nutritional supplements is highly recommended in the sports environment in Beirut city.

Maximal oxygen uptake, ventilatory thresholds and mechanical power during cycling in tropical climate in Guadeloupean elite cyclists.

The Tropical climate imposes a high level of physiological stress, which could modify the target heart rate in training load prescription, as the recommendations are often determined by maximal oxygen uptake testing in temperature-neutral laboratories. To test this hypothesis, 7 high-level cyclists performed two randomised maximal tests in neutral (19.2±0.9°C; 51.7±1.3% RH) and Tropical environment (25.8±1.1°C; 63.7±2.3% RH). Neither maximal oxygen uptake nor ventilatory threshold was influenced by the environmental conditions. However, ventilation (p<0.005) and the respiratory equivalent in O(2) (p<0.05) were significantly higher in the Tropical environment, whereas maximal power output and the time to attain maximal oxygen uptake were significantly lower (p<0.05 for both). Moreover, the ventilatory cost of cycling (expressed in LW(-1)) was significantly greater in the Tropical condition (0.40±0.03LW(-1) vs. 0.32±0.05LW(-1), in Tropical vs. Neutral; condition effect: p<0.005; condition × time: p<0.001). Rectal temperature was influenced by neither the environmental conditions nor exercise (36.7±0.1 and 37.0±0.1°C vs. 36.8±0.1 and 37.1±0.2°C, in Tropical vs. Neutral, before and after exercise) but was influenced by condition × time (p<0.05). The heart rate (HR) values usually used for training prescription were not significantly different (154±5bpm vs. 156±4bpm and 172±4bpm vs. 167±4bpm in Tropical vs. Neutral climate, for the first and second thresholds, respectively). We concluded that the usual parameters measured during maximal exercise to establish training programs are not impaired in moderate Tropical environment. Nevertheless, the thermal stress attested by the increased ventilatory cost of cycling could have prevented the cyclists from performing a true maximal test in Tropical conditions.

Energy expenditure and dietary intake in overweight versus non-overweight guadeloupian adults / Gasto de energía e ingesta dietética en guadalupanos adultos con sobrepeso frente a aquellos sin sobrepeso

OBJECTIVE: Obesity is the source of many health problems in Guadeloupe. The aim of this study was to describe the relationships between daily energy intake and expenditure, and weight status. METHODS: Three consecutive daily recalls for activities and food intake were used to assess energy expenditure and energy intake in 20to 60year old Guadeloupian men and women. RESULTS: The absolute daily energy expenditure was correlated to the body weight (r = 0.64, p > 0.001) and to the daily energy intake with more strength in the normalweight group (r = 0.52, p < 0.001) than in the overweight group (r = 0.26, p < 0.05). in both weight groups, the higher the metabolism was, the larger was the difference between energy intake and energy expenditure. CONCLUSION: Under-reporting was probably present in overweight women. However, higher energy intake and expenditure were observed in larger persons who were consequently not identified as less active.

OBJETIVO: La obesidad es fuente de muchos problemas de salud en Guadalupe. El objetivo de este estudio fue describir las relaciones entre la ingesta energética y el gasto de energía diarios, y el estado del peso. MÉTODOS: Tres reportes consecutivos diarios sobre las actividades y la ingesta de alimentos, fueron usados para evaluar el gasto de energía y el consumo de energía fueron usados el consume de alimentos fueron usados para evaluar el gasto de energía y la ingesta energética en hombres y mujeres guadalupanos de 20 a 60 años de edad. RESULTADOS: El valor absoluto del gasto diario de energía fue correlacionado con el del peso del cuerpo (r = 0.64, p > 0.001) y la ingesta diaria de energía con más fuerza en el grupo de peso normal (r = 0.52, p < 0.001 que en el grupo de sobrepeso (r = 0.26, p < 0.05). en ambos grupos, mientras más alto era el metabolismo, mayor era la diferencia entre la ingesta y el consumo de energía. CONCLUSIÓN: En el caso de las mujeres obesas, probablemente los reportes quedaron por debajo de la realidad. Sin embargo, se observaron ingesta y gasto de energía más altos en personas más corpulentas, que por consiguiente no fueron identificadas como menos activas.

Energy expenditure and dietary intake in overweight versus non-overweight Guadeloupian adults.

OBJECTIVE: Obesity is the source of many health problems in Guadeloupe. The aim of this study was to describe the relationships between daily energy intake and expenditure, and weight status. METHODS: Three consecutive daily recalls for activities and food intake were used to assess energy expenditure and energy intake in 20- to 60-year-old Guadeloupian men and women. RESULTS: The absolute daily energy expenditure was correlated to the body weight (r = 0.64, p > 0.001) and to the daily energy intake with more strength in the normal-weight group (r = 0.52, p < 0.001) than in the overweight group (r = 0.26, p < 0.05). In both weight groups, the higher the metabolism was, the larger was the difference between energy intake and energy expenditure. CONCLUSION: Under-reporting was probably present in overweight women. However, higher energy intake and expenditure were observed in larger persons who were consequently not identified as less active.

Asian Indians of Guadeloupe are less physically active than their island counterparts.

The status of ethnic minority has been reported to be associated with a tendency toward sedentary behavior. The Guadeloupean population is composed of Afro-Caribbeans and an Asian Indian minority. This study examined the association of ethnicity and physical activity on the island. Energy expenditures (EE), energy intakes (EI), and macronutrient intakes of 122 Guadeloupean workers (60 Indians and 62 controls) were assessed by three consecutive 24-h recalls. Two-way analyses of variance were conducted to test the hypothesis of an effect of ethnicity, taking the potential effect of sex into account, on these variables. Asian Indians reported lower EE (P=0.011), lower EE/EI ratios (P=0.001), and lower physical activity (P=0.003) than their Afro-Carribean counterparts. Their food intakes were not different in terms of EI or macronutrient intake. No sex x ethnicity interactions were significant. The present study reports a tendency toward physical inactivity in Asian Indians of Guadeloupe associated with EI similar to those of controls. Sedentary lifestyles and energetic imbalances are well-documented risk factors for several diseases, including type 2 diabetes and cardiovascular disease, both major public health concerns in Guadeloupe. Strategies to prevent sedentary lifestyles should be considered for Asian Indian Guadeloupeans.

Ventilatory and lactic thresholds in subjects with sickle cell trait.

This study investigated 1) whether ventilatory and lactic thresholds (VT and LT, respectively) are different in sickle cell trait carriers (SCTc) and subjects with normal hemoglobin (control group), and 2) whether the first LT and VT and the second LT and VT are respectively coincident in the two populations. Seven SCTc and 8 control subjects performed an incremental exercise test (IET). Blood lactate concentration and cardioventilatory variables were analyzed at rest and during IET. No significant difference in the ventilatory parameters (notably, maximal oxygen uptake [VO (2max)] and the ventilatory thresholds) or the lactic thresholds was observed between the two groups. In both SCTc and control subjects, the LTs and VTs did not occur at the same exercise intensity. The first VT did not coincide with the first LT, in contrast with the second VT and the second LT, which coincided in both groups. In conclusion, SCTc exhibited normal ventilatory and lactic responses during a progressive and maximal exercise test assessing aerobic physical fitness.

The effect of 8 days of training in tropical environment on performance in neutral climate in swimmers.

The tropical climate imposes a high level of physiological stress during exercise. As a result of this stress, adaptations may be induced and could benefit athletes upon return to a neutral climate. To test this hypothesis, climate effects on swimming performance were assessed in 16 swimmers: 6 trained for 8 days in a tropical climate, 6 trained for 8 days at altitude, and 4 served as a tapering group. The swimming performance was assessed during a 400-m freestyle before the experimental period, and at 10 days and 30 days after. The results demonstrated that only the tropical group increased performance (10.0 +/- 4.2 %, p < 0.03 for the tropical group 30 days after return). No significant change in performance was noted for the two other groups 10 or 30 days post-training. The results of the present study demonstrated that training in a tropical climate significantly enhances performance in swimmers 30 days after return to neutral climate. However, further studies are needed to evaluate the effects of such a climate on performance in other sports.

Putative protective effect of inspiratory threshold loading against exercise-induced supraspinal diaphragm fatigue.

The present investigation was intended to assess the consequences of an inspiratory load on the diaphragm central component of fatigue during exercise. We recorded the motor potential evoked (MEP) by transcranial magnetic stimulation of the motor cortex in 10 subjects. The diaphragm and rectus femoris were studied before and 10, 20, and 40 min after two 16-min cycling exercise (E) trials requiring 55% of maximal oxygen uptake: 1) one with an inspiratory threshold load (E + ITL), corresponding to 10% of maximal inspiratory pressure; and 2) the other without the load (E). Dyspnea, heart rate, electromyographic activity of the sternocleidomastoid, and diaphragm work were significantly higher in E + ITL than in E. Neither trial affected the response to phrenic magnetic stimulation, which was performed 15 and 25 min postexercise, or the maximal inspiratory pressure (116 and 120 cm H(2)O before E and E + ITL, respectively, and 110 and 114 cm H(2)O at 30 min postexercise). Whereas the amplitude of the diaphragm MEP was unaffected by E + ITL (+2.1 +/- 29.4%), a significant decrease was observed 10 min after E compared with baseline (-37.1 +/- 22.3%) and compared with E + ITL. The MEP amplitude of rectus femoris remained unchanged with E and E + ITL. The recruitment of synergistic agonists during E + ITL may have normalized the major ventilatory stress and reset up the excitability of the diaphragm pathway.

Mouth pressure twitches induced by cervical magnetic stimulation to assess inspiratory muscle fatigue.

This study aimed at determining whether twitch mouth pressure (TwPmo) induced by cervical magnetic stimulation (CMS) was sensitive to inspiratory muscle fatigue produced by whole body exercise (WBE) in normal subjects. Twenty subjects performed one or two of the following protocols: (i). cycling at 85% V(O(2),max) until exhaustion; (ii). inspiratory resistive load (IRL) breathing at 62% of maximal inspiratory pressure until task failure. In eight subjects, oesophageal (TwPoes), gastric (TwPga) and transdiaphragmatic (TwPdi) pressures were recorded. The TwPmo was significantly reduced (P<0.05) 20 min after both WBE and IRL, from 17.5+/-4.4 to 15.9+/-3.9 cmH(2)O and from 19.4+/-4.9 to 17.7+/-4.5 cmH(2)O, respectively. Subsequently to IRL, the TwPdi decrease was associated with a reduction in TwPoes/TwPga ratio; not after WBE. Independently of the mode of ventilatory loading, inspiratory muscle fatigue was detected. Thus, inspiratory muscle fatigue after WBE can be assessed in normal subjects with a noninvasive technique.

Contribution of respiratory acidosis to diaphragmatic fatigue at exercise.

The factors that may modulate ventilatory muscle fatigue during exercise are controversial. In this study the contribution of acidosis to exercise-induced diaphragmatic fatigue was investigated, using measurements of the twitch mouth pressure response (tw,Pmo) to cervical magnetic stimulation. After learning sessions, 14 healthy subjects performed two cycling tests (at 60% of maximal aerobic power for 16 min), one while breathing spontaneously (mean minute ventilation (V'E) 67.9 L x min(-1)) and the other while hypoventilating voluntarily (mean V'E 53.8 L x min(-1)). Exercise was voluntarily set at a moderate power to avoid a fatiguing effect of exercise per se. As compared with spontaneous breathing (SB), voluntary hypoventilation (VHV) significantly increased mean carbon dioxide tension in arterial blood (Pa,CO2) (51 mmHg versus 41 mmHg) and significantly decreased arterial pH (7.28 versus 7.34). After 10 min of SB test, tw,Pmo was unchanged compared to the baseline value (19.1 versus 18.5 cmH2O) whereas tw,Pmo fell significantly as compared to baseline (17.1 versus 18.5 cmH2O) and to SB (17.1 versus 19.1 cmH2O) after the VHV test. The results of this study suggest that exposure to hypercapnia may impair respiratory muscle function. This impairment could be more clinically relevant in patients with chronic obstructive lung disease.