Growth hormone/IGF-I-dependent signaling restores decreased expression of the myokine SPARC in aged skeletal muscle.

Skeletal muscle exerts many beneficial effects on the human body including the contraction-dependent secretion of peptides termed myokines. We have recently connected the myokine secreted protein acidic and rich in cysteine (SPARC) to the formation of intramuscular adipose tissue (IMAT) in skeletal muscle from aged mice and humans. Here, we searched for inducers of SPARC in order to uncover novel treatment approaches for IMAT.

FGF-2-dependent signaling activated in aged human skeletal muscle promotes intramuscular adipogenesis.

Aged skeletal muscle is markedly affected by fatty muscle infiltration, and strategies to reduce the occurrence of intramuscular adipocytes are urgently needed. Here, we show that fibroblast growth factor-2 (FGF-2) not only stimulates muscle growth but also promotes intramuscular adipogenesis. Using multiple screening assays upstream and downstream of microRNA (miR)-29a signaling, we located the secreted protein and adipogenic inhibitor SPARC to an FGF-2 signaling pathway that is conserved between skeletal muscle cells from mice and humans and that is activated in skeletal muscle of aged mice and humans.

Genetic deletion of microRNA biogenesis in muscle cells reveals a hierarchical non-clustered network that controls focal adhesion signaling during muscle regeneration.

Objective: Decreased muscle mass is a major contributor to age-related morbidity, and strategies to improve muscle regeneration during ageing are urgently needed. Our aim was to identify the subset of relevant microRNAs (miRNAs) that partake in critical aspects of muscle cell differentiation, irrespective of computational predictions, genomic clustering or differential expression of the miRNAs.

Methods: miRNA biogenesis was deleted in primary myoblasts using a tamoxifen-inducible CreLox system and combined with an add-back miRNA library screen.

Acute Impact of Recovery on the Restoration of Cellular Immunological Homeostasis.

In view of the growing amount of (intense) training in competitive sports, quick recovery plays a superior role in performance restoration. The aim of the present study was to compare the effects of active passive recovery during high-intensity interval training (HIIT) and sprint interval training (SIT) protocols on acute alterations of circulating blood cells. Twelve male triathletes/cyclists performed 1) a HIIT consisting of 4×4 min intervals, 2) a SIT consisting of 4×30s intervals, separated by either active or passive recovery.

Uncoupling protein 1 expression in adipocytes derived from skeletal muscle fibro/adipogenic progenitors is under genetic and hormonal control.

Background: Intramuscular fatty infiltration is generally associated with the accumulation of white adipocytes in skeletal muscle and unfavourable metabolic outcomes. It is, however, still unclear whether intramuscular adipocytes could also acquire a brown-like phenotype. Here, we detected intramuscular expression of brown adipocyte markers during fatty infiltration in an obesity-resistant mouse strain and extensively compared the potential of two different stem cell populations residing in skeletal muscle to differentiate into brown-like adipocytes.

Reply to: Could superimposed electromyostimulation be an effective training to improve aerobic and anaerobic capacity? Methodological considerations for its development.

In the present reply, we would like to put forward our perspective on the points raised by Amaro-Gahete et al. The main concerns addressed by the authors deal with the stimulation modalities applied in our study, compared to the results of Miyamoto et al. (Eur J Sports Sci 16(8):1104-1110, 2016), who showed an increase in the first ventilatory threshold and VO after 16 × 30 min low-frequency neuromuscular electrical stimulation (NMES).

Chronic effects of superimposed electromyostimulation during cycling on aerobic and anaerobic capacity.

Purpose: To examine if chronic endurance training by means of simultaneously applied, superimposed electromyostimulation (EMS) can be used to improve performance and physiological core parameters compared to the traditional cycling.

Methods: Twenty-one male subjects (VO 55.2 ± 5.

Impact of high-intensity and high-volume exercise on short-term perturbations in the circulating fraction of different cell types.

Background: High-intensity training (HIT) can improve endurance performance and VO2max more effectively than high-volume training (HVT). Hence, the implementation of HIT protocols such as 4x30 s "all-out" and 4x4 min at 90-95% VO2max is currently existent in various sports. However, there is limited awareness of the acute changes in blood cell count following these protocols.

Effects of active vs. passive recovery during Wingate-based training on the acute hormonal, metabolic and psychological response.

Objective: The exercise-induced metabolic stress can be influenced by the mode of recovery and is associated with acute hormonal responses. Therefore, it is hypothesized that active recovery between high intensity intervals reduces the metabolic stimulus and therefore the hormonal response compared to passive recovery.

Design: 12 male cyclist/triathletes performed four 30s all-out intervals, either with active (A) or passive (P) recovery between each bout.