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.

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.