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Physiological adaptations were investigated following a strength-endurance (S-E) block prescribed with accentuated eccentric loading (AEL) or traditional resistance training (TRAD). Recreationally trained participants (n = 11 males, 6 females, age = 23.2 ± 4.2 yrs, body mass (BM) = 81.3 ± 22.2 kg, height = 172.1 ± 10 cm) completed a four-week block of concurrent resistance, sprint, and change of direction training. Participants were assigned one of two training conditions, AEL (n = 9) or TRAD (n = 8). Training was identical, except AEL performed 110% eccentric overloading every 1st, 3rd, 5th, 7th, and 9th repetition during back squat (BS) and bench press (BP). Body composition, summated muscle size (ACSAsum) and thickness (MTsum), regional ACSA and MT, and region-specific fascicle angle (FA) and length (FL) were assessed pre- (PRE) and post-training (POST). External work was calculated and exercise displacement was measured to determine the mechanical stimulus provided. Physiological variables were analyzed using multiple mixed analysis of variance (ANOVA). External work and displacement were analyzed with independent Welch’s t-tests. A statistically significant main effect of Time was observed for ACSAsum and ICW (p < 0.05); however, there were no statistically significant Time x Condition interaction effects observed for any dependent variable (p > 0.05). Time x Length interaction effects also failed to reach statistical significance for regional ACSA or regional MT (p > 0.05). Moreover, Time x Position interaction effects were not statistically significant for regional MT (p > 0.05). There were also no statistically significant interaction effects observed for regional FA or FL (p > 0.05). Differences in external work did not reach statistical significance (p > 0.05). A four-week S-E training block, performed with or without AEL, increases muscle size, but results in only minor architectural alterations. Additionally, AEL appears to induce unique region-specific hypertrophy. In contrast, TRAD seems to induce greater increases in ICW, potentially indicating greater sarcoplasmic hypertrophy. Interestingly, 110% eccentric overloading did not lead to statistically greater work performed, although differences may be practically significant when allometrically scaled. Researchers and practitioners should examine region-specific musculoskeletal adaptations, when possible, to more accurately assess training effects.

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<p>Self control is affected by self-regulatory strength depletion (Hagger et al., 2010) as well as construal-level mindset (Fujita et al., 2006). However, two conflicting perspectives have emerged predicting differential interactive effects of construals and depletion. The purpose of the present study was to investigate the independent and interactive effects of construal levels and self-control strength in an effortful cycling exercise task. Using a randomized 2 X 2 factorial design, undergraduate participants (<em>N </em>= 67, <em>n</em> = 34 women) completed a baseline cycling task, followed by a self-control depletion manipulation (Stroop task vs. quiet rest; Wallace & Baumeister, 2002), a construal-level manipulation (category vs. exemplar naming task; Fujita et al., 2006), and then a 10-minute strenuous cycling test trial. The results showed no main effects for either self-control strength depletion or construal level (<em>p</em> > .20). However there was a near-significant interaction effect (<em>p </em>= .07) indicating the depleted group outperformed the non-depleted group in the low-construal condition, whereas the opposite effect occurred in the high-construal condition. The results provide novel insights of the effects of self-control strength depletion and construal mindsets on exercise performance and implications for the design of construal level and self-control depletion research.</p> / Master of Science (MSc)

<p> Exercise intensity is one of the major factors determining the utilization of carbohydrates (CHO) and lipids in mammalian skeletal muscle. Using indirect calorimetry, we determined maximal oxygen uptake (VO2max) and whole-body rates of CHO and lipid oxidation in rats selectively bred for high and low running capacity (HCR's and LCR's) during exercise at 50, 60, 70 and 80%VO2max. Previous studies have revealed a pattern of selection where mammals with different aerobic capacities use the same proportions of lipids and CHO when exercising at the same relative exercise intensity and as intensity increases, CHO use increases and lipid use decreases. The present results showed that the HCR's had a VO2max and distance run to exhaustion that was 1.3 and 4.0 times greater than the LCR's respectively. Also, both groups of rats followed the pattern of fuel selection seen in previous studies where the same proportions (in%) of lipids and CHO are used at the same relative exercise intensity. On an absolute scale, the HCR's used more lipids and CHO than the LCR's at all exercise intensities but the results were not always statistically significant. We also determined the exercise intensity that elicited the greatest lipid use to be 60% VO2max in both groups.</p> <p> In order to explain these patterns of fuel selection, metabolic indicators, metabolites and enzymes, in skeletal muscle were measured at rest and post exercise for one hour at 60%VO2max. Specifically, ATP and phosphocreatine (PCr) metabolite concentrations were determined in the medial and lateral gastrocnemius, extensor digitorum longus (EDL), tibialis anterior (TA), and soleus muscle. The medial gastrocnemius and soleus were analyzed (pre and post exercise samples were combined) for their oxidative and glycolytic enzyme activity by measuring citrate synthase (CS), cytochrome oxidase (COX), β-hydroxyacyl CoA dehydrogenase (HOAD), and lactate dehydrogenase (LDH) . PCr and ATP concentrations did not change pre and post exercise and between the HCR's and LCR's except for the EDL where there was a significant decrease (P<0.05) in both metabolites after exercise in both groups of rats. For the enzyme measurements, CS and COX activities were higher (P<0.05) in the HCR's for the soleus and HOAD activities were also higher in the HCR's medial gastrocnemius compared to the LCR's. We concluded that the HCR's have a greater oxidative capacity as shown by their greater aerobic and endurance capacity (VO2max and distance to exhaustion), their ability to oxidize a greater absolute amount of lipids and CHO's at the same relative exercise intensity, and their higher activities of oxidative enzymes in the soleus (CS and COX) and medial gastrocnemius (HOAD). Future research into the mechanisms involved in explaining these patterns of fuel selection may include examining fatty acid transport proteins, fatty acid and CHO availability, fiber types, and catecholamines.</p> / Thesis / Master of Science (MSc)

Glucose is a fundamental energy source, the utilization and regulation of which impacts exercise performance and health. These studies have used modeling techniques to evaluate glucose kinetics and dynamics in equids and developed tests to evaluate the status of glucose metabolism. In Part I, 12 exercise-trained Arabians underwent insulin-modified FSIGT (with minimal model analysis) and single-injection glucose tracer (with compartmental analysis) studies at rest and during exercise to evaluate the effects of exercise on glucose kinetics and dynamics. These geldings were maintained on pasture, but adapted for 4 months to twice-daily feeding of feeds rich in sugar and starch (SS, n=6: NSC 45%, Fat 3%, NDF 24%) or fat and fiber (FF, n=6:NSC 13%, Fat 11%, NDF 45% ). Exercise increased insulin sensitivity (P = 0.070) and glucose transport (P < 0.038). Although variables were not different between FF and SS horses at rest, during exercise SS horses tended to have lower (P = 0.085) insulin sensitivity and increased (P = 0.043) glucose utilization compared to FF horses. In Part II, satisfactory proxies for minimal model parameters were developed to facilitate the evaluation of insulin sensitivity in larger populations. These proxies were applied to a population of 163 ponies and used to characterize metabolic differences between ponies predisposed to pasture laminitis (PL) from ponies not predisposed (NL). A subset of 14 ponies (7 PL, 7 NL) also underwent the FSIGT for minimal model analysis. Ponies predisposed to laminitis were found to have lower insulin sensitivity (P < 0.007) and higher insulin secretory response (P < 0.045) by both the minimal model and proxies, and higher (P < 0.001) circulating triglycerides and body condition score. Cut-point analysis for these variables was used to define a pre-laminitic metabolic syndrome with total predictive power of 78% to identifity ponies at risk for developing pasture laminitis. Increased insulin resistance and prevalence of lamintis were associated with increased non-structural carbohydrates in spring pasture. These studies demonstrate the importance of glucose regulation for exercise and animal health. When glucose regulation is altered in the case of insulin resistance, performance could be impacted and diseases such as laminitis may occur. Insulin resistance may be moderated by exercise or by avoiding sugar and starch in feeds and pasture. / Ph. D.