Diving response after a one-week diet and overnight fasting

Background

We hypothesized that overnight fasting after a short dietary period, especially with carbohydrates, could allow performing breath-hold diving with no restraint for diaphragm excursion and blood shift and without any increase of metabolism, and in turn improve the diving response.

Methods

During two separate sessions, 8 divers carried out two trials: (A) a 30-m depth dive, three hours after a normal breakfast and (B) a dive to the same depth, but after following a diet and fasting overnight. Each test consisted of 3 apnea phases: descent, static and ascent whose durations were measured by a standard chronometer. An impedance cardiograph, housed in an underwater torch, provided data on trans-thoracic fluid index (TFI), stroke volume (SV), heart rate (HR) and cardiac output (CO). Mean blood pressure (MBP), arterial O₂ saturation (SaO₂), blood glucose (Glu) and blood lactate (BLa) were also collected.

Results

In condition B, duration of the static phase of the dive was longer than A (37.8 ± 7.4 vs. 27.3 ± 8.4 s respectively, P < 0.05). In static phases, mean ∆ SV value (difference between basal and nadir values) during fasting was lower than breakfast one (−2.6 ± 5.1 vs. 5.7 ± 7.6 ml, P < 0.05). As a consequence, since mean ∆ HR values were equally decreased in both metabolic conditions, mean ∆ CO value during static after fasting was lower than the same phase after breakfast (−0.4 ± 0.5 vs. 0.4 ± 0.5 L · min⁻¹ respectively, P < 0.05). At emersion, despite the greater duration of dives during fasting, SaO₂ was higher than A (92.0 ± 2.7 vs. 89.4 ± 2.9 % respectively, P < 0.05) and BLa was lower in the same comparison (4.2 ± 0.7 vs. 5.3 ± 1.1 mmol∙L⁻¹, P < 0.05).

Conclusions

An adequate balance between metabolic and splancnic status may improve the diving response during a dive at a depth of 30 m, in safe conditions for the athlete’s health.

Inter-individual Variability in Psychological Outcomes of Supervised Exercise in Adults with Type 2 Diabetes / Variabilidad interindividual en los efectos psicológicos del ejercicio supervisado en adultos con diabetes tipo 2

Abstract:Exercise is a key component in the management of Type 2 Diabetes Mellitus (T2DM), however despite the strong evidence of its protective effects, a majority of the population with this diagnosis remains inactive and those who start an exercise program are not willing to train themselves over the long-term. Self-efficacy and perceived stress are related to barriers to exercise in T2DM, therefore the aim of this longitudinal study is to investigate variations across time and individual differences in both variables as effects of a supervised exercise training (6 months) in a small sample of persons diagnosed with T2DM. Results show a general decline in the mean values of self-efficacy and perceived stress at 6 months and a high individual variability in both variables. These results support the need to develop customized programs of exercise in T2DM that take into account different phases of the exercise process and individual variability. Resumen:El ejercicio es un componente clave en la prevención y el tratamiento de Diabetes Mellitus Tipo 2 (DMT2); sin embargo, a pesar de la fuerte evidencia de sus efectos protectores, la mayoría de las personas con este diagnóstico permanece inactiva y aquellos que comienzan un programa de ejercicio no están dispuestos a entrenar a largo plazo. La autoeficacia y la percepción de estrés se relacionan con las barreras para realizar ejercicio en pacientes T2DM; por lo tanto, el objetivo de este estudio longitudinal consiste en investigar las variaciones a través del tiempo y las diferencias individuales en ambas variables, como efectos de un entrenamiento de ejercicio supervisado (6 meses), en una muestra pequeña de pacientes diagnosticados con TD2M. Los resultados muestran una disminución general de los valores promedio de la autoeficacia y del estrés percibido a los 6 meses y una alta variabilidad individual en ambas variables. Estos resultados apoyan la necesidad de desarrollar programas personalizados de ejercicio en pacientes T2DM con el objetivo de considerar las diferentes fases del proceso de ejercicio y de la variabilidad individual.

Differences in hemodynamic response to metaboreflex activation between obese patients with metabolic syndrome and healthy subjects with obese phenotype

Patients suffering from obesity and metabolic syndrome (OMS) manifest a dysregulation in hemodynamic response during exercise, with an exaggerated systemic vascular increase. However, it is not clear whether this is the consequence of metabolic syndrome per se or whether it is due to concomitant obesity. The aim of the present investigation was to discover whether OMS and noncomplicated obesity resulted in different hemodynamic responses during the metaboreflex. Twelve metabolically healthy but obese subjects (MHO; 7 women), 13 OMS patients (5 women), and 12 normal age-matched controls (CTL; 6 women) took part in this study. All participants underwent a postexercise muscle ischemia protocol to evaluate the metaboreflex activity. Central hemodynamics were evaluated by impedance cardiography. The main result shows an exaggerated increase in systemic vascular resistance from baseline during the metaboreflex in the OMS patients as compared with the other groups (481.6 ± 180.3, −0.52 ± 177.6, and −60.5 ± 58.6 dynes·s−1·cm−5 for the OMS, the MHO, and the CTL groups, respectively; P < 0.05). Moreover, the MHO subjects and the CTL group showed an increase in cardiac output during the metaboreflex (288.7 ± 325.8 and 703.8 ± 276.2 ml/m increase with respect to baseline), whereas this parameter tended to decrease in the OMS group (−350 ± 236.5 ml/m). However, the blood pressure response, which tended to be higher in the OMS patients, was not statistically different between groups. The results of the present investigation suggest that OMS patients have an exaggerated vasoconstriction in response to metaboreflex activation and that this fact is not due to obesity per se.

Body composition changes affect energy cost of running during 12 months of specific diet and training in amateur athletes

Considering the relation between body weight composition and energy cost of running, we tested the hypothesis that by modifying body composition by means of a combined protocol of specific diet and training, the energy cost of motion (Cr) may be reduced. Forty-five healthy and normal-weight subjects were divided into 3 groups that performed a different treatment: the first group attended a dietary protocol (D), the second group participated in a running program (R), and the third group followed both the dietary and running protocols (R&D). Each subject underwent 3 anthropometric and exercise evaluation tests during 1 year (at entry (T0), month 6 (T6), and month 12 (T12)) to assess body composition and Cradjustments. The mean fat mass (FM) values were reduced in R&D from 12.0 ± 4.0 to 10.4 ± 3.0 kg (p < 0.05 T0 vs. T12) and in the D group from 14.2 ± 5.8 to 11.6 ± 4.7 kg (p < 0.05 T0 vs. T12). Conversely, the mean fat free mass values increased in R&D (from 56.3 ± 8.8 to 58.3 ± 9.8 kg, p < 0.05 T0 vs. T12) and in the D group (from 50.6 ± 13.2 to 52.9 ± 13.6 kg, p < 0.05 T0 vs. T12). The mean Cr values of the 2 groups were significantly modified throughout the 1-year protocol (1.48 ± 0.16 and 1.40 ± 0.15 kcal·kg–b·km−1in the R&D group at T0 and T12, respectively; 1.83 ± 0.17 and 1.76 ± 0.23 kcal·kg–b·km−1in D group at T0 to T12, respectively). The R&D and D groups that underwent the diet protocol had a positive change in body composition during the year (FM/fat free mass ratio decline), which determined a Crreduction.

Cardiovascular responses during free-diving in the sea

Cardiac output has never been assessed during free-diving diving in the sea. Knowledge of human diving response in this setting is therefore scarce. 3 immersions were performed by 7 divers: at depths of 10 m, 20 m and 30 m. Each test consisted of 3 apnea phases: descent, static and ascent. An impedance cardiograph provided data on stroke volume, heart rate and cardiac output. Mean blood pressure, arterial O2 saturation and blood lactate values were also collected. Starting from a resting value of 4.5±1.6 L∙min(-1), cardiac output at 10 m showed an increase up to 7.1±2.2 L∙min(-1) (p<0.01) during the descent, while conditions during the static and ascent phases remained unchanged. At 20 m cardiac output values were 7.3±2.4 L∙min(-1) and 6.7(±1).2 L∙min(-1) during ascent and descent, respectively (p<0.01), and 4.3±0.9 L∙min(-1) during static phase. At 30 m cardiac output values were 6.5±1.8 L∙min(-1) and 7.5±2 L∙min(-1) during descent and ascent, respectively (p<0.01), and 4.7±2.1 L∙min(-1) during static phase. Arterial O2 saturation decreased with increasing dive depth, reaching 91.1±3.4% (p<0.001 vs. rest) upon emergence from a depth of 30 m. Blood lactate values increased to 4.1±1.2 mmol∙L(-1) at the end of the 30 m dive (p<0.001 vs. rest). Results seem to suggest that simultaneous activation of exercise and diving response could lead to an absence of cardiac output reduction aimed at an oxygen-conserving effect.

Muscle ischemic preconditioning does not improve performance during self-paced exercise

Muscle ischemic preconditioning (IP) has been found to improve exercise performance in laboratory tests. This investigation aims at verifying whether performance is improved by IP during self-paced exercise (SPE) in the field. 11 well-trained male runners performed 3 randomly assigned 5 000 m self-paced running tests on an outdoor track. One was the reference (RT) test, while the others were performed following muscle IP (IPT) and a control sham test (ST). Average speeds were measured during each test. Mean values in oxygen uptake (VO2), aerobic energy cost (AEC) during race and post-race blood lactate (BLa) were gathered. Data showed that none of the studied variables were affected by IPT or ST with respect to the RT test. Average speeds were 4.63±0.31, 4.62±0.31 and 4.60±0.25 m·s(-1) for the RT, the ST and the IPT tests, respectively. Moreover, there was no difference among tests in speed reached during each lap. VO2 was 3.5±0.69, 3.74±0.85 and 3.62±1.19 l·min(-1). AEC was 1.04±0.15, 1.08±0.1 and 1.09±0.15 kcal·kg(-1)·km(-1). Finally, post-race BLa levels reached 12.85±3.54, 11.88±4.74 and 12.82±3.6 mmol·l(-1). These findings indicate that performance during SPE is not ameliorated by ischemic preconditioning, thereby indicating that IP is not suitable as an ergogenic aid.

Type 2 diabetes mellitus, physical activity, exercise self-efficacy, and body satisfaction. An application of the transtheoretical model in older adults

Physical activity (PA) is a relevant component of the treatment of Type 2 diabetes mellitus (T2DM). However, to prevent its related morbidities, PA requires an immediate and lasting change of lifestyle. Exercise self-efficacy and body satisfaction were used in a sample of older adults with T2DM, classified in different stages of change, to predict levels of PA. Results show that exercise self-efficacy increases linearly from precontemplation to maintenance stage, while body satisfaction shows an inverted U shape. However, only stages of change, other than exercise self-efficacy, add a significant and noticeable contribution to prediction of levels of PA. This evidence claims a tailored approach to PA in older adults with T2DM and advises behavioural health interventions based on exercise self-efficacy.

Assessment of circulatory adjustments during underwater apnoea in elite divers by means of a portable device

AIM

Considering that sympathetic activation is induced by exercise, it is reasonable to assume that hemodynamic adjustments to exercise act in opposition to those elicited by the diving response. However, cardiovascular measurements have never been performed during underwater dynamic apnoea (DA), and this hypothesis remains speculative.

METHODS

Data concerning heart rate (HR), stroke volume (SV) and cardiac output (CO) during static apnoea (SA) and DA were collected from 12 elite divers by means of an impedance cardiograph adapted to the underwater environment. Mean arterial pressure (MBP), systemic vascular resistance (SVR) and arterial oxygen saturation (SaO(2)) were also assessed. Five trials were performed by the divers: head-out immersion during normal breathing (test A); 3 min of SA immersed at the surface (B) and at 3 m depth (C); DA till exhaustion immersed at the surface (D) and at 3 m depth (E).

RESULTS

Both B and C conditions led to bradycardia (-17%) compared to A and also induced a decrement in SV (-8%) and in CO (-25%), while MBP was maintained because of an increase in SVR. A significant MBP increment (+11%) was detected only during tests D and E, when a SaO(2) drop was also present, whereas HR, SV and CO remained unchanged.

CONCLUSION

We concluded that typical diving response was present only during SA, while sympathetic activation was induced by exercise during DA, which partially obscured the effects of the diving response.

Comparison of the Recent-Onset Arthritis Disability questionnaire with the Health Assessment Questionnaire disability index in patients with rheumatoid arthritis

BACKGROUND

Physical disability in patients with rheumatoid arthritis (RA) is often assessed by questionnaires. We compared the Recent-Onset Arthritis Disability (ROAD) questionnaire with the Health Assessment Questionnaire (HAQ) disability index (DI) in a cohort of RA patients. The aim of this study was to obtain information on several aspects of construct validity of these measures.

METHODS

A cross-sectional multicentre study was carried out among patients with RA who were attending hospital outpatient clinics. The patient group included 196 patients partially or not responding to disease modifying anti-rheumatic drugs. For the evaluation of the psychometric properties of the ROAD in comparison with HAQ-DI this population has been compared to another cohort of 247 outpatients with RA who were participating in a long-term observational study. All patients completed the ROAD and HAQ-DI. Additional comparator composite indices of disease activity were analysed. The ROAD structural validity was first assessed using exploratory factor analysis. Concurrent validity was analysed by Spearman's correlations and cross-tabulations. Discriminant validity to distinguish patients with active and non-active disease was assessed with receiver operating characteristic (ROC) curve analysis. For agreement analysis Bland and Altman plots were calculated.

RESULTS

Factor analysis yielded a two-factor ROAD score that accounted for 68.74% of the explained variance in the questionnaire. The first factor, namely upper extremity function/activity daily living and work (ROAD-upper) accounted for 55.6% of the explained variance. The second factor, namely lower extremity function (ROAD-lower) accounted for 13.1% of the explained variance. Significant correlations were found between the scores of the ROAD and the other clinical variables with a high ability to measure pain and disease activity, supporting the concept of convergent construct validity. The discriminatory power of both questionnaires to assess inactive and active RA patients was good, without significant difference.

CONCLUSIONS

ROAD is a good alternative to the HAQ-DI for the assessment of physical disability in RA. Use of the ROAD makes it easier and less costly to collect data and reduces the burden on RA patients and should be applied in both clinical trials and routine clinical care settings.

Psychometric properties of an index of three patient reported outcome (PRO) measures, termed the CLinical ARthritis Activity (PRO-CLARA) in patients with rheumatoid arthritis. The NEW INDICES study

OBJECTIVES

To evaluate the psychometric properties of an index based on 3 patient reported outcomes measures, termed PRO-CLinical ARthritis Activity (PRO-CLARA), in order to facilitate rapid and easy rheumatoid arthritis (RA) activity assessment in daily routine.

METHODS

196 patients partially or not responding to disease modifying anti-rheumatic drugs (DMARDs), consented to participate in a multicentre cross-sectional study. For the evaluation of the psychometric properties of the PRO-CLARA, this population has been compared to another cohort of 247 outpatients with RA who were participating in a long-term observational study and who satisfying minimal disease activity and remission definitions. All patients completed the PRO-CLARA, combining patient's physical function, self-administered tender joint count and perception of global health status into a single measure of disease activity. Additional comparator composite indices were analysed. Internal consistency was assessed with Cronbach's alpha coefficient. A confirmatory factor analysis was carried out to test factor structure. Concurrent validity was analyzed using Spearman's correlations and cross-tabulations. Discriminant validity to distinguish patients with active and non-active disease was assessed with receiver operating characteristic (ROC) curve analysis. For agreement analysis, kappa statistics were calculated.

RESULTS

In testing for internal consistency, we found that Cronbach's alpha for the PRO-CLARA was 0.893, indicating high reliability. PRO-CLARA proved to be significantly correlated to established RA activity assessment tools. The area under ROC curve of the PRO-CLARA gives identical results to those provided by other comparator indices.

CONCLUSIONS

The study showed satisfactory psychometric properties of the PRO-CLARA.