Reference values for triceps surae tissue oxygen saturation by near-infrared spectroscopy

OBJECTIVE

To establish the reference values for peripheral tissue perfusion of the triceps surae muscle assessed by NIRS at rest and in progressive effort.

APPROACH

A total of 288 apparently healthy individuals of both sex were included; between 30 and 79 years of age; nonsmokers; without diagnosis of diabetes mellitus, systemic arterial hypertension, kidney disease, symptoms of angina and intermittent claudication, or any musculoskeletal alteration that would prevent physical exertion; and without diagnosis of PAD or other symptoms associated. All individuals performed anthropometric measurements, physical activity levels, and tissue oxygen saturation (StO2) assessments during and after arterial occlusion maneuver and incremental shuttle walking test by NIRS. The variables obtained by NIRS were presented in percentiles (P) for general comparison between sex and comparison between sexes according to age group. The relationship between the NIRS data and other variables was tested.

MAIN RESULTS

Considering P50 and p<0.05, men had lower StO2 values, higher deoxygenation and reoxygenation (Tx-reox) rates at rest, and higher Tx-reox during progressive effort. There were correlations (p<0.0001) of body composition with the lowest StO2 and Tx-reox values and functional capacity with Tx-reox in occlusion and Tx-reox.

SIGNIFICANCE

The percentiles presented can clinically assist in the diagnosis and monitoring of different health conditions; however, it is important to consider the individual's sex, body composition, and functional capacity.

The ACTN3 genotype in soccer players in response to acute eccentric training

Genetic factors can interfere with sporting performance. The identification of genetic predisposition of soccer players brings important information to trainers and coaches for individual training loads adjustment. Different responses to eccentric training could be observed by the genotype referred to as α-actinin-3 (ACTN3) in biomarkers of muscle damage, hormones and inflammatory responses. The aim of this study was to compare acute inflammatory responses, muscle damage and hormonal variations according to the eccentric training in soccer professional athletes with different genetic profiles of ACTN3 (XX, RX and RR). 37 soccer professional athletes (9 XX, 13 RX, 15 RR) were randomly divided into five stations associated to eccentric muscle contraction and plyometrics. Blood samples were taken from athletes pre-eccentric training, immediately after (post), 2- and 4-h post-eccentric training to determine hormone responses (cortisol and testosterone), muscle damage (CK and α-actin), and inflammatory responses (IL-6). After eccentric training, athletes XX presented higher levels for CK (4-h post), α-actin (post and 2-h post) and cortisol (post) compared to RR and RX athletes. However, RR and RX athletes presented higher levels of testosterone (post) and IL-6 (2 h post and 4 h post) compared to athletes XX. The main conclusion of this study is that professional soccer athletes homozygous to ACTN3XX gene are more susceptible to eccentric damage and present a higher catabolic state, demonstrated by metabolic, hormonal and immune responses post an eccentric training, in comparison to ACTN3RR and ACTN3RX groups.