| dc.description.abstract | Mitogen Activated Protein Kinases (MAPKs) have been implicated in cellular signal transduction leading to cellular growth and differentiation in skeletal muscle following exercise. This dissertation provides a review of the published literature describing the role and actions of the MAPK pathways particularly the ERK1/2 and p38 pathways in response to exercise and to nutritional supplements. Two separate but related investigations were conducted. The first sought to elucidate the effect of various permutations of acute resistance exercise programming using a high concentric velocity (high power) back squat exercise on the mitogen activated protein kinases ERK1/2 and p38. The second investigation examined the effect of 8 weeks of resistance training with and without a multi-ingredient caffeinated pre-workout supplement on the same two MAPK pathways (p38 and ERK1/2), and other performance variables. Taken together these two studies show the response of ERK1/2 and p38 to resistance exercise programing variables and resistance exercise training status. This information taken in light of the previous research has significant implications for strength and conditioning coaches, trainers, and therapists who are seeking to increase muscular strength and hypertrophy for any number of reasons. RESEARCH ABSTRACT FOR STUDY 1 PURPOSE: The purpose of this study was to determine the effect of three different high power back squat protocols and the associated muscular power production on the MAPKs, ERK1/2 and p38. Power fatigue across sets was also considered METHODS: Nine recreationally trained males (21.4±1.67 years, 202.9±21.4 lbs.), completed each of three speed squat protocols in randomized order. The three testing protocols consisted of 5 sets of 10 repetitions at 30% of 1RM; 5 sets of 5 repetitions at 70% of 1RM; and 5 sets of 3 repetitions at 90% of 1RM. Average and peak power measurements were obtained by Tendo Weightlifting Analyzer for 7 of the subjects. Resting and post exercise blood lactate and muscle biopsies were taken. Western blot analysis was completed for ERK1/2 and p38 as well as their phosphorylaed counterparts. RESULTS: Blood lactate increased similarly between the three testing protocols. Analysis of power measures identified a significant main effect for load (F=10.23, p= 0.004), but not for set, p >0.05). The average power was lower for the 90% protocol than for the 30% protocol (F= 28.96, p0.05). The average power was lower for the 90% protocol than for the 30% protocol (F= 28.96, p(2,16) = 5.514, p=0.015). CONCLUSIONS: Resistance load appears to affect power fatigue across five sets of resistance exercise. The heaviest load had the highest power fatigue, while the light and moderate loads did not show any evidence of power fatigue. The exercise modality, training status of the subjects, and/or the timing may account for the limited MAPK response to resistance exercise in this study. RESEARCH ABSTRACT FOR STUDY 2 PURPOSE: The purpose of this study was to examine the acute and training effects with and without a multi-ingredient high caffeine pre-workout supplement on squat and bench press power, vertical jump, and the mitogen activated protein kinase (MAPK) pathways (ERK1/2 and p38). METHODS: Twenty four of thirty physically active collegiate (19.5±0.269 yr) males completed this double blind placebo controlled investigation. Subjects in the Experimental group (EXP) (n=14) consumed a multi-ingredient, high caffeine (450mg) pre-exercise supplement 10-15 minutes before each training session. Subjects in the Control group (CON) (n=10) drank a non-caloric placebo at the same times. Both groups completed an eight week resistance training program (3days/wk). Squat and bench press power and vertical jump were measured before and after the 8 weeks of resistance training. Muscle biopsies were also taken before and after the first and last workouts of the training program. Separate repeated measures ANOVAs were performed to test for differences between EXP and CON groups for power as well as total, phosphorylated and the relative ratio of phosphorylated to total ERK1/2 and p38. RESULTS: Squat power measurements showed a significant group by time interaction (F(1/22) =4.857, p=0.038). Vertical Jump and bench press power did increase with training, but did not differ between groups. Not only did ERK phosphorylation and the ratio of phophorylation increase after exercise (F (1,22) = 4.854, p = 0.38; F(1,22) = 5.159, p=0.033) but there was evidence that the ERK1/2 exercise response was is reduced after weeks of training (F(1,22) = 6.607, p=0.017). P38 was increased following training, but there was no effect of exercise bout on the phosphorylation on p38 in this study. DISCUSSION: Only one of the three power measurements, squat power, was benefited by the supplementation. EXP group than the CON group, the supplement did not affect any ERK1/2 or p38 measures. Eight weeks of pre-workout supplementation may provide some muscle performance benefit when combined with resistance exercise training. This study supports previous findings that ERK1/2 phosphorylation following exercise is blunted by exercise training. | |
