Access to abstract permanently restricted to Ball State community only / Access to thesis permanently restricted to Ball State community only / School of Physical Education, Sport, and Exercise Science

Access to abstract permanently restricted to Ball State community only / Access to thesis permanently restricted to Ball State community only / School of Physical Education, Sport, and Exercise Science

The purpose of this investigation was to determine the effect of passive and active recovery on the resynthesis of muscle glycogen after high intensity cycle ergometer exercise in untrained subjects. In a cross over design, six college-age males performed three, one min exercise bouts, at 130% V02max with a 4 min rest period between each work bout. Subjects refrained from exercise for two days prior to testing, and consumed a 15% carbohydrate solution (300g sugar in 2000ml of water) the day before each trial to help elevate glycogen concentration. The exercise protocol for each trial was identical, while the recovery following exercise was eitheractive (40-50% VO2max) or passive. The initial muscle glycogen values averaged 144.2 mmol•kg-1 w.w. for the active trial and 158.7 mmol•kg-1 w.w. for the passive trial. Corresponding post-exercise glycogen contents were 97.7 and 106.8 mmol•kg-1 w.w., respectively. These differences were not significant (P>0.05). However, the rate of muscle glycogen resynthesis during passive recovery increased 15 mmol•kg-1 w.w. whereas it decreased 6.27 mmol•kg-1 w.w. following active recovery (P<0.01). Also, the decrease in blood lactate concentration during active recovery was much faster than during passive recovery and significantly different at 10 and 30 min of the recovery period (P<0.01). The major finding of this investigation was that the rate of muscle glycogen resynthesis during passive recovery was significantly greater than that during active recovery. These data suggest that lactate can be used as an endogenous glycogenic precusor in muscle, and that glycogenesis was the prevalent pathway of lactate removal during passive recovery following high intensity cycle ergometer exercise. / Human Performance Laboratory

Insulin resistance is commonly developed in obesity and is a trait of the beginning stage of type 2 diabetes mellitus (DM). It is highly likely that the high plasma fatty acid levels provoke the condition in the obese and insulin resistant state of type 2 DM. Hence, the purpose of this study was to determine if a high concentration of palmitic acid causes insulin resistance and how ceramide content is regulated under the various conditions in the isolated rat soleus muscle. A submaximal insulin stimulus (100 ,aU/ml) increased 3-O-methylglucose transport by -2.7 fold over basal conditions in the soleus (1.90 ± 0.23 µmol•ml"1•hr-1 vs. 5.06 ± 0.38 µmol•ml-1•hr-1, respectively) (P < 0.05). Five hours of palmitic acid preincubation induced a significant decrease in insulin-stimulated glucose transport (3.49 ± 0.11 µmol•ml-1•hr-1) by -31 % (P < 0.05) compared with the control. By contrast, the addition of L-cycloserine, a serine palmitoyltransferase inhibitor, attenuated the palmitic acid response by -20% (4.19 ± 0.27 µmol•ml-1•hr-1) (P < 0.05). A 5 hr preincubation with 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR), an adenosine analogue that increase AMP activated protein kinase, increased glucose transport (3.29 ± 0.1 µmol•ml-1•hr-1) (P < 0.05) compared with the control group. Moreover, regardless if palmitic acid or L-cycloserine were present, insulin-stimulated glucose uptake was normalized (5.30 ± 0.38 µmol•ml-1•hr-1 and 5.56 ± 0.16 µmol•ml"1•hr-1, respectively) after 5 hr AICAR preincubation. We next measured the ceramide content to investigate whether the reduced glucose uptake results from ceramide accumulation in the soleus. The total ceramide mass in the soleus was increased by -35% in palmitic acid-treated group compared with the control group (122.02 ± 2.07 pmol•mg-1 vs. 90.79 + 1.24 pmol•mg 1, respectively) (P<0.05). Both L-cycloserine and AICAR decreased palmitateinduced ceramide synthesis by -20% and -14%, respectively (97.15 + 2.5 pmol•mg-1 and 105.79 ± 1.94 pmol•mg-1, respectively) (P<0.05) compared with the palmitic acid-treated group. We also measured serine palmitoyltransferase (SPT) to determine if AICAR regulates ceramide synthesis by inhibiting SPT. Total SPT protein level increased by -27% (P<0.05) and SPT activity increased by -44% (P<0.05) compared with the control group. By contrast, after muscles were incubated with L-cycloserine for 5 hr, both SPT protein level and enzyme activity were decreased by -17% and -23%, respectively (P<0.05). In adition, 5 hr AICAR treatment blunted palimitic acid-induced SPT protein level and enzyme activity by 11% (P<0.05) and 20% (P<0.05), respectively, compared with the palmitic acid-treated group. In conclusion, these data suggest that short term exposure (5 hr) to high fatty acid levels appears to cause insulin resistance by increasing ceramide accumulation and that AMPK expression (AICAR treatment) can attenuate the problem by regulating SPT levels. / School of Physical Education, Sport, and Exercise Science

The aim of this research was to investigate myogenic (i.e. growth) and proteolytic (i.e. breakdown) gene expression (GE) in skeletal muscle of young and old women. Myogenic (MyoD, MRF4, Myf5, myogenin, myostatin) and proteolytic (Atrogin-1, MuRF-1, FOXO3A) genes were examined in the basal state and after resistance exercise (RE). Six old women (OW: 85 ± 1 y) and eight young women (YW: 23 ± 1) performed 3 x 10 knee extensions at 70% of 1-repetition-maximum. Muscle biopsies were obtained from the vastus lateralis (i.e. thigh) before and 4 hours after RE.In the basal state, OW expressed higher levels (p<0.05) of MyoD, MRF4, myf5, myogenin, myostatin, FOXO3A and MuRF-1 compared to YW. Fiber type specific GE analysis in the OW showed that slow-twitch muscle fibers (MHC I) expressed higher levels (p<0.05) of myogenin and Atrogin-1, compared to fast-twitch (MHC Ila) fibers. In response to RE both YW and OW increased (p<0.05) mRNA levels of MyoD and MRF4, while a decrease (p<0.05) was observed for myostatin. MuRF-1 mRNA increased (p<0.05) in both age groups, while there was an age-specific induction (p<0.05) of Atrogin-1 after RE. Fiber type specific GE after RE in the old women showed that MHC Ila fibers did not induce myogenic GE. Robust increases (p<0.05) in MyoD, MRF4, and myogenin were only observed in the MHC I fibers. Both fiber types decreased (p<0.05) myostatin, and increased Atrogin-1 with RE. MuRF-1 mRNA levels increased specifically in MHC Ila fibers. In summary, skeletal muscle of OW expresses higher levels of mRNA for most selected genes at rest. With RE, aging skeletal muscle retains the ability to induce myogenic GE, although exclusive to MHC I fibers. After RE, proteolytic GE induction is greater in OW and most pronounced in MHC Ila fibers. Collectively, these data suggest that an imbalance exists in the regulation of the myogenic and proteolytic program in aging skeletal muscle. This research also provides the first evidence of intrinsic molecular differences between MHC I and MHC Ila fibers in OW, and may, in part, explain the MHC Ila atrophy apparent in sarcopenic muscle. / School of Physical Education, Sport, and Exercise Science

The purpose of this study was to examine the influence of a supplement containing polyunsaturated phoshphatidylcholine (PPC) on physical performance, delayed muscle soreness (DOMS), markers of membrane damage, and lipid peroxidation after repeated bouts of whole body resistance on men ages 18-35 years. Subjects were randomly assigned to receive either PPC or placebo supplements for 31 days. After 3 weeks of supplementation, subjects were to perform 3 whole body resistance exercise sessions with 3 days of recovery between sessions. In order to document the effects of supplementation on recovery, fasting blood samples for determination of creatine kinase (CK) and malondialdehyde (MDA), and muscle soreness ratings were obtained each day in the morning after the initial 3 weeks of supplementation. The data was analyzed using a two-way ANOVA. The results indicate notable trends favoring PPC supplementation, such as lower ratings of perceived muscle soreness, lower CK and MDA responses to repeated bouts, improved maintenance of upper body strength and power, and increased lean body mass. However, these findings were not statistically different when compared to the placebo group. / School of Physical Education

The purpose of this study was to compare the anabolic response to acute running exercise in two different leg muscles in endurance-trained men using two different stable isotope tracers. 6 male subjects (26±2 yr; V02max 63±2 ml•kg-' •min-') performed a 45 min treadmill run at 77±1 % intensity. Infusions of d3-leucine and d5-phenylalanine were used to measure mixed muscle FSR at rest and 24 hr post-exercise. An additional infusion of 10% amino acid solution was added to the post-exercise infusion to maximize the muscle anabolic response. Muscle biopsies were obtained from the vastus lateralis (VL) and soleus (SOL) at 2 and 6 hr of the infusion for the measurement of isotope incorporation. Additional muscle biopsies were obtained prior to and 4 hr post-exercise for determination of muscle glycogen use. At rest FSR was similar between the VL and SOL using either tracer (p>0.05). At 24 hr post-exercise FSR was elevated in both muscles, independent of the tracer used (p<0.05). Muscle glycogen was decreased to the same extent in both muscles by -31% at 4 hr post-exercise (p<0.05). These data suggest that the VL and SOL muscles are both stimulated similarly during 45 min of level grade running. Additionally, both muscles respond similarly 24 hr post-exercise, independent of the tracer used for the determination of protein synthesis. / School of Physical Education, Sport, and Exercise Science

The purpose of this investigation was to comprehensively examine the influence of progressive aerobic exercise training on whole muscle size and function in older women (65-80 yr). Three sedentary, healthy, females (66±1 yrs, 167±2 cm, 70±7 kg) performed 12 weeks of supervised progressive cycle training (42 training sessions 3-4 sessions/week up to 80% HRR). Subjects were tested before and after training for maximum aerobic capacity (VO2max), quadriceps cross sectional area (CSA), whole muscle specific tension, concentric 1-RM, maximum voluntary contraction (MVC), and concentric peak power (wafts). On average, the three subjects improved VO2max (34%), quadriceps CSA (10%), MVC (37%), whole muscle specific tension (25%), and concentric peak power (19%). These positive changes indicate that aerobic exercise may positively influence muscle size and function in the elderly. / School of Physical Education, Sport, and Exercise Science

The aim of this investigation was to compare the acute anabolic and catabolic responses of male and female vastus lateralis (VL) and soleus (SOL) muscles in response to resistance exercise (RE). Muscle biopsies from the VL of 7 males (26±3 y, 75±8 kg) and 7 females (25±3 y, 59±5 kg) were obtained before, and 2 and 6 h after 4 x 7 supine-squat, and 4 x 14 calf-press exercises at maximal effort using inertial ergometry. The mRNA levels of select myogenic (MyoD, myogenin, MRF4), proteolytic (atrogin-1 , MuRF-1), myostatin, and inflammatory (IL-6, -8, -15) genes were quantified using real-time RT-PCR. Male VL vs SOL: The SOL had higher basal mRNA levels of myogenic, proteolytic, and inflammatory genes. After exercise, the myogenic response was similar between the VL and SOL. Both muscles increased MuRF-1 similarly at 2 h, whereas 6 h post-RE proteolytic gene expression (GE) was suppressed in the VL but not in the SOL. The SOL had a reduction in myostatin GE, and a more robust inflammatory response compared to the VL. These findings indicate a more favorable growth response in the VL. Gender comparisons: VL – Basally, the male VL had higher levels of myogenic, proteolytic, myostatin, and inflammatory mRNA compared to the female VL. After exercise, both genders increased myogenic GE similarly. Both genders increased MuRF-1 initially, with females also increasing atrogin-1 and myostatin post-RE. At 6 h, males decreased proteolytic GE to below basal levels. Females also had a greater inflammatory response than males. These findings indicate a greater growth response to RE in the male VL as compared to the female VL. SOL – After exercise, both genders increased myogenic GE in the SOL, but only males increased MyoD expression. Males increased MuRF-1 mRNA but decreased myostatin GE, while females decreased atrogin-1. The inflammatory response was similar between males and females. Despite the modest differences, the net response of the female and male SOL was similar, and indicated a molecular response slightly favorable for growth. / School of Physical Education, Sport, and Exercise Science

[Truncated abstract] It is well established that fish, amphibians and reptiles recovering from physical activity of near maximal intensity can replenish completely their muscle glycogen stores in the absence of food. In contrast, the extent to which these stores are replenished under these conditions in humans has been reported in all but one study to be partial. This implies that a few consecutive bouts of intense exercise might eventually lead to the sustained depletion of the muscle glycogen stores in humans if food is unavailable, thus limiting their capacity to engage in fight or flight behaviors unless mechanisms exist to protect muscle glycogen against sustained depletion. The objective of Study 1 was to test this prediction. Eight participants performed three intense exercise bouts each separated by a recovery period of 75 minutes. Although only 53% of muscle glycogen was replenished after the first exercise bout (postexercise and post-recovery glycogen levels of 246 ± 25 and 320 ± 36 mmol.kg-1 dry mass, respectively), all the glycogen mobilised during the second and third bouts was completely replenished during the respective recovery periods, with glycogen reaching levels of 319 ± 29 mmol.kg-1 dry mass after recovery from the third bout. These findings show that humans are not different from other vertebrate species in that there are conditions where humans have the ability to completely replenish without food intake the muscle glycogen mobilised during exercise. The results of our first study raise the intriguing possibility that humans have pre-set muscle glycogen levels that are protected against sustained depletion, with the extent to which muscle glycogen stores are replenished after exercise being dependent on the amount of glycogen required to attain those protected levels. ... During recovery, glycogen levels in the NORM group increased by more than ~50% and reached levels close to those alleged to be protected (189 ± 21 mmol.kg-1 dry mass), whereas no glycogen was deposited in the HCHO group. The sustained post-exercise activation of glycogen synthase, the transient fall in whole body carbohydrate oxidation rate, the increased mobilisation of body proteins, and the prolonged elevation in NEFA levels most probably played important roles in enabling glycogen synthesis in the NORM group. In conclusion, this thesis shows for the first time that there are some conditions (e.g. low pre-exercise muscle glycogen levels) where humans recovering from intense exercise have the capacity, like other species, to replenish completely their muscle glycogen stores from endogenous carbon sources. This study also suggests that humans protect preset levels of muscle glycogen against sustained depletion and at levels high enough to support at least one maximal sprint effort to exhaustion. Evidence is also provided for the existence of a feedback mechanism whereby glycogen below their protected levels mediate the activation of glycogen synthase to restore the depleted muscle glycogen stores back to their protected levels. Our findings, however, leave us with a number of novel unanswered questions which clearly show that the regulation of glycogen metabolism is far from the simple process generally depicted in most textbooks of biochemistry.