Inefficient skeletal muscle oxidative function flanks impaired motor neuron recruitment in Amyotrophic Lateral Sclerosis during exercise.

This study aimed to evaluate muscle oxidative function during exercise in amyotrophic lateral sclerosis patients (pALS) with non-invasive methods in order to assess if determinants of reduced exercise tolerance might match ALS clinical heterogeneity. 17 pALS, who were followed for 4 months, were compared with 13 healthy controls (CTRL). Exercise tolerance was assessed by an incremental exercise test on cycle ergometer measuring peak O2 uptake ([Formula: see text]O2peak), vastus lateralis oxidative function by near infrared spectroscopy (NIRS) and breathing pattern ([Formula: see text]E peak). pALS displayed: (1) 44% lower [Formula: see text]O2peak vs. CTRL (p < 0.0001), paralleled by a 43% decreased peak skeletal muscle oxidative function (p < 0.01), with a linear regression between these two variables (r2 = 0.64, p < 0.0001); (2) 46% reduced [Formula: see text]Epeak vs. CTRL (p < 0.0001), achieved by using an inefficient breathing pattern (increasing respiratory frequency) from the onset until the end of exercise. Inefficient skeletal muscle O2 function, when flanking the impaired motor units recruitment, is a major determinant of pALS clinical heterogeneity and working capacity exercise tolerance. CPET and NIRS are useful tools for detecting early stages of oxidative deficiency in skeletal muscles, disclosing individual impairments in the O2 transport and utilization chain.

Body Water Status and Short-term Maximal Power Output during a Multistage Road Bicycle Race (Giro d'Italia 2014).

An investigation of whether body water changes during the Giro d'Italia affected average maximal mean power (MMP) of different time durations and to establish whether phase-angle and body cell mass (BCM) are related to MMP in elite cyclists. Approximately 2 h after each stage of the race, a bioelectrical impedance analysis was performed on 8 cyclists and analysed according to bioelectrical impedance vector analyses. Additionally, MMP of different time durations were recorded during each stage. Body mass increased (p<0.001), vector-length shortened (p<0.001) and MMP15 (maximal mean power for 15 s; p=0.043) decreased in the course of the Giro d'Italia. The shortening of the vector was negatively related to MMP10 (r=- 0.749, p=0.032) and MMP15 (r=- 0.735, p=0.038) during stage 16 (heavy mountain-stage) and MMP60 (r=- 0.751, p=0.032), MMP300 (r=- 0.739, p=0.036) and MMP1800 (r=- 0.769, p=0.026) during stage 19 (time-trial). Additionally, the baseline phase-angle and BCM were associated to MMP15 best (r=0.781, p=0.022 and 0.756, p=0.030, respectively). In the course of the Giro d'Italia, MMP15 decreased, indicating progressive fatigue. The vector-length shortening and to some extent the body mass increase indicate that cyclists gained body water during the race. This gain was positively associated with performance during the last stages, possibly due to improved thermoregulation. Furthermore, phase-angle and BCM, shown to be linked to cellular function and to represent metabolic active tissue, reflect individual MMP of short duration in professional road cyclists.