Interactions of aging, overload, and creatine supplementation in rat plantaris muscle

Attenuation of age-related sarcopenia by creatine supplementation has been equivocal. In this study, plantaris muscles of young (Y; 5m) and aging (A; 24m) Fisher 344 rats underwent four weeks of either control (C), creatine supplementation (Cr), surgical overload (O), or overload plus creatine (OCr). Creatine alone had no effect on muscle fiber cross-sectional area (CSA) or heat shock protein (HSP70) and increased myonuclear domain (MND) only in young rats. Overload increased CSA and HSP70 content in I and IIA fibers, regardless of age, and MND in IIA fibers of YO rats. CSA and MND increased in all fast fibers of YOCr, and CSA increased in I and IIA fibers of AOCr. OCR did not alter HSP70, regardless of age. MND did not change in aging rats, regardless of treatment. These data indicate creatine alone had no significant effect. Creatine with overload produced no additional hypertrophy relative to overload alone and attenuated overload-induced HSP70 expression

Metabolic characteristics of keto-adapted ultra-endurance runners

Background: Many successful ultra-endurance athletes have switched from a high-carbohydrate to a low-carbohydrate diet, but they have not previously been studied to determine the extent of metabolic adaptations. Methods: Twenty elite ultra-marathoners and ironman distance triathletes performed a maximal graded exercise test and a 180 min submaximal run at 64% VO2max on a treadmill to determine metabolic responses. One group habitually consumed a traditional high-carbohydrate (HC: n = 10, %carbohydrate:protein:fat = 59:14:25) diet, and the other a low-carbohydrate (LC; n = 10, 10:19:70) diet for an average of 20 months (range 9 to 36 months). Results: Peak fat oxidation was 2.3-fold higher in the LC group (1.54 ± 0.18 vs 0.67 ± 0.14 g/min; P = 0.000) and it occurred at a higher percentage of VO2max (70.3 ± 6.3 vs 54.9 ± 7.8%; P = 0.000). Mean fat oxidation during submaximal exercise was 59% higher in the LC group (1.21 ± 0.02 vs 0.76 ± 0.11 g/min; P = 0.000) corresponding to a greater relative contribution of fat (88 ± 2 vs 56 ± 8%; P = 0.000). Despite these marked differences in fuel use between LC and HC athletes, there were no significant differences in resting muscle glycogen and the level of depletion after 180 min of running (− 64% from pre-exercise) and 120 min of recovery (− 36% from pre-exercise). Conclusion: Compared to highly trained ultra-endurance athletes consuming an HC diet, long-term keto-adaptation results in extraordinarily high rates of fat oxidation, whereas muscle glycogen utilization and repletion patterns during and after a 3 hour run are similar

Excess post-exercise oxygen consumption response to a bout of resistance exercise

To examine the excess postexercise oxygen consumption (EPOC) response following a bout of heavy resistance exercise (HRE), seven healthy males (age = 22 f 3 yr; height = 177 -+ 8 cm; mass = 83 f 10 kg, percent body fat = 10.4 f 4.2%) who weight trained recreationaly, engaged in a 31-minute bout of HRE. The bout consisted of four circuits of bench press, power cleans, and squats, selected to recruit most major muscle groups. Each set was performed using the subject's predetmnined ten-repetition maximum and continued until failure. Each set was followed by a two-minute rest interval. Oxygen consumption (Va)m measurements were obtained at regular intervals throughout the day, before and after HRE (34 h pm, 29 h pre, 24 h pre, 10 h pre, 5 h pre, immediate post, 14 h post, 19 h post, 24 h post, 38 h post, 43 h post, 48 h post). Postexercise V02 measurements were compared to the baseline measurements that corresponded with the same time of day. A repeated measures ANOVA revealed that EPOC was significantly elevated @ 5 0.05) immediately, 14.19, and 38 hours post-exercise. Mean daily V q values for both post-exercise days were also significantly elevated above the baseline day. These results suggest that EPOC duration and magnitude following HRE may exceed the EPOC produced by following moderate aerobic exercise. Furthermore, the cumulative energy expenditure as a result of EPOC following HRE may exceed the combined total energy expended during and after aerobic exercis

No change in skeletal muscle satellite cells in young and aging rat soleus muscle

Satellite cells are muscle stem cells capable of replenishing or increasing myonuclear number. It is postulated that a reduction in satellite cells may contribute to age-related sarcopenia. Studies investigating an age-related decline in satellite cells have produced equivocal results. This study compared the satellite cell content of young and aging soleus muscle in rat, using four different methods: dystrophin-laminin immunohistochemistry, MyoD immunohistochemistry, electron microscopy, and light microscopy of semi-thin sections. The absolute quantity of satellite cells increase with age, but satellite cell percentages were similar in young and aging soleus muscles. There were no differences in satellite cell quantity among MyoD immunohistochemistry, electron microscopy, and semi-thin sections. All three methods had significantly more satellite cells than with dystrophin-laminin immunohistochemistry. We conclude that satellite cell number does not decrease with age and postulate that satellite cell functionality may be responsible for age-related sarcopenia

A description of the lumbar interfascial triangle and its relation with the lateral raphe: anatomical constituents of load transfer through the lateral margin of the thoracolumbar fascia

Movement and stability of the lumbosacral region is contingent on the balance of forces distributed through the myofascial planes associated with the thoracolumbar fascia (TLF). This structure is located at the common intersection of several extremity muscles (e.g. latissimus dorsi and gluteus maximus), as well as hypaxial (e.g. ventral trunk muscles) and epaxial (paraspinal) muscles. The mechanical properties of the fascial constituents establish the parameters guiding the dynamic interaction of muscle groups that stabilize the lumbosacral spine. Understanding the construction of this complex myofascial junction is fundamental to biomechanical analysis and implementation of effective rehabilitation in individuals with low back and pelvic girdle pain. Therefore, the main objectives of this study were to describe the anatomy of the lateral margin of the TLF, and specifically the interface between the fascial sheath surrounding the paraspinal muscles and the aponeurosis of the transversus abdominis (TA) and internal oblique (IO) muscles. The lateral margin of the TLF was exposed via serial reduction dissections from anterior and posterior approaches. Axial sections (cadaveric and magnetic resonance imaging) were examined to characterize the region between the TA and IO aponeurosis and the paraspinal muscles. It is confirmed that the paraspinal muscles are enveloped by a continuous paraspinal retinacular sheath (PRS), formed by the deep lamina of the posterior layer of the TLF. The PRS extends from the spinous process to transverse process, and is distinct from both the superficial lamina of the posterior layer and middle layer of the TLF. As the aponeurosis approaches the lateral border of the PRS, it appears to separate into two distinct laminae, which join the anterior and posterior walls of the PRS. This configuration creates a previously undescribed fat-filled lumbar interfascial triangle situated along the lateral border of the paraspinal muscles from the 12th rib to the iliac crest. This triangle results in the unification of different fascial sheaths along the lateral border of the TLF, creating a ridged-union of dense connective tissue that has been termed the lateral raphe (Spine, 9,1984, 163). This triangle may function in the distribution of laterally mediated tension to balance different viscoelastic moduli, along either the middle or posterior layers of the TLF