Skeletal muscle satellite cells (SC) are essential in muscle repair and regeneration. The role of SCs in mediating hypertrophic adaptations following resistance training has been widely studied. Recent evidence from endurance training studies suggest that SCs may also play a role in mediating non-hypertrophic adaptations. Indeed, it has been shown that satellite cells respond to endurance training. Work in rodent models suggest that exercise intensity may play an important role in expanding the SC pool whereas the results of endurance training studies in humans are much less consistent. Limited evidence also suggest that exercise intensity may be important in mediating exercised-induced capillarization following endurance training in humans. In both instances, it is unknown whether the on-and-off pattern characteristic of interval training (i.e. the rest-work cycles) plays a role in the magnitude of these skeletal muscle responses to this type of exercise. Thus, we sought to determine if the rest-to-work cycle plays a role in the scope of these skeletal muscle responses by comparing the SC response and capillarization to two distinct work-matched protocols that are performed at the same intensity but at two different exercise patterns (interval versus continuous). We hypothesized that interval exercise will elicit a greater SC response and induce greater capillary growth compared to work-matched continuous exercise. Ten young active individuals performed 12 sessions of counterweighted single-leg cycling over 4 weeks. Each leg was randomly assigned to Interval (INT) (10 x 3-min intervals at 50% of single leg peak power output (PPO), with 1 min recovery) or Continuous (CONTIN) (30 min at 50% PPO, followed by 10 min recovery), which were performed 5 min apart on each day, in an alternating order. Resting muscle biopsies were obtained from the vastus lateralis pre- and post-training. Immunofluorescent microscopy of muscle cross sections was used to assess muscle fibre capillarization, SC expansion and activation. Western blot analysis was performed on pro-angiogenic factors, specifically VEGF and VEGFR2. Mixed muscle SC activation increased in the INT leg compared to the pre-training time-point (3.2 ± 0.5 vs. 1.5 ± 0.2 Pax7+/MyoD+ cells/ 100 myofibers, respectively; P < 0.05). Mixed muscle SC activation did not increase significantly in the CONTIN leg compared to the pre-training time-point and there was no significant difference in activation between CONTIN and INT post-training. With regards to capillarization, no differences in type I or type II muscle fibre CC (capillary contacts), C/Fi (individual capillary-to-fibre ratio) or CFPE (capillary-to-fibre perimeter exchange index) were observed post-training or between legs. No significant expansion of the SC pool occurred in either legs post-training and no increases in fibre cross-sectional area was observed. This study presents novel evidence of mixed muscle SC activation following interval exercise training that is not observed following work- and intensity-matched continuous exercise training. This suggest that the rest-to-work cycle associated with interval exercise may dictate, to some extent, SC activation whereas it may not be a primary stimulus for training-induced changes in capillarization. / Thesis / Master of Science (MSc)

In vitro and animal studies indicate that the response to heat stress is associated with beneficial adaptations that promote cell health and survival. Few studies to date have examined this finding in human subjects, and it is unclear how the adaptation compares in magnitude to exercise training. The purpose of this study was to investigate the skeletal muscle adaptations (namely mitochondrial biogenesis and capillarization) of 6 weeks of deep-muscle heat treatment relative to exercise training. We hypothesized that heat treatment (HT), applied through pulsed shortwave diathermy (2 hr, 3 days/week) over a 6-week intervention period would lead to increased mitochondrial content and capillarity within skeletal muscle, though to a lesser extent than single-leg knee extension exercise training (EX; 40 min, 3 days/week). We randomized 28 sedentary but otherwise healthy, young adults (ages 18–36; n = 13 female, n = 15 male) to receive either HT, EX, or sham heating sessions (CON; 2 hr, 3 days/week) over 6 weeks. Diathermy increased muscle temperature by 3.2 ± 0.33 C (P < 0.0001) within 20 minutes. Muscle biopsies were taken from the vastus lateralis at baseline, after 3 weeks of intervention and again after 6 weeks of intervention. Following 3 and 6 weeks of heat treatment, we did not observe significant changes in mitochondrial biogenesis or capillarization. However, exercise training was sufficient to elicit an increase in individual capillary-to-fiber ratio (P = 0.0003), capillary density (P = 0.0428), and the Capillary to Fiber Perimeter Exchange Index (P = 0.0089). Significant increases in the expression of mitochondrial protein Complexes I (P = 0.0073) and IV (P = 0.0015), were observed in the exercise group, but not the heat or control groups. These results indicate that 6 weeks of localized HT, when applied to young healthy individuals, is insufficient to induce mitochondrial biogenesis or capillarization in skeletal muscle. Additionally, our findings provide support for the extensive body of literature that connect exercise training to beneficial skeletal muscle adaptations.

A capilarização da informação no território brasileiro por meio do smartphone e suas implicações espaciais são resultado da convergência das técnicas de telefonia e internet, cuja rede expande seu alcance para atender à demanda crescente de conexão, sob a regulação de agentes públicos e privados que determinam a implementação e o uso dessas infraestruturas. Os sistemas técnicos que compõem essa rede se fundamentam em lógicas, intenções e investimentos, induzindo seu aperfeiçoamento para a produção e o consumo desses objetos e das informações que por eles fluem de forma banalizada. O papel do smartphone é de conector e ponto de acesso, e seu funcionamento presume uma lógica reticular, pela qual as redes e as distâncias não contíguas não impedem relações cotidianas. As resultantes espaciais dos movimentos de produção, consumo, distribuição e capilarização dessa rede incidem em diferentes escalas do território, sob a influência das relações interescalares e de ordens e intencionalidades de agentes envolvidos no controle dessa rede. / The information networks capillarization in Brazilian territory through the smartphone and its spatial implications are the result of the telephony and internet techniques convergence, whose network expands its reach to meet the increasing demand for connection, under the regulation of public and private agents that determine the implementation and use of these infrastructures. The technical systems that make up this network are based on logic, intentions and investments, inducing their improvement for the production and consumption of these objects and the information that they flow in a trivial way. The role of the smartphone is of connector and access point, and its operation presumes a reticular logic, in which the networks and the noncontiguous distances do not impede daily relations. The spatial results of the movements of production, consumption, distribution and capillarization of this network affect different scales of the territory, under the influence of the interscalar relations and orders and intentionalities of agents involved in the control of this network.

Chronic obstructive pulmonary disease (COPD) is one of the leading causes of morbidity and mortality worldwide. Besides abnormities within the respiratory system COPD is also associated with effects outside the lungs, so called systemic effects. One systemic effect that has been highlighted is skeletal muscle dysfunction which has also been associated with reduced exercise capacity. Apart from changes in muscle morphology, low levels of physical activity have also been suggested as a plausible mediator of reduced exercise capacity in COPD. The aim of this thesis was to study muscle morphology and physical activity patterns in patients with different degrees of COPD and to examine the associations between muscle morphology, physical activity and exercise capacity in these patients. Skeletal muscle morphology was found to shift towards a more glycolytic muscle profile in COPD patients and changes in muscle morphology were found to be correlated to disease severity and to exercise capacity. Muscle capillarization was also found to be lower in COPD compared with healthy subjects and to be correlated to disease severity and exercise capacity. When studying signalling pathways involved in muscle capillarization, an overexpression of VHL was found in patients with mild and moderate COPD compared with healthy subjects. Furthermore, COPD patients were found to be less physically active compared with healthy subjects and the level of physical activity was associated with exercise capacity.In conclusion, changes in skeletal muscle morphology and low levels of physical activity are present in COPD patients and may partly explain the lower exercise capacity observed in these patients. The more glycolytic muscle profile in COPD is suggested to be mediated by hypoxia and low levels of physical activity in this patient group. Furthermore, increased levels of VHL may lead to impaired transduction of the hypoxic signalling pathway, which may contribute to the decreased muscle capillarization observed in COPD.