David E. Lee1, James D. Fluckey2, Mats I. Nilsson2, Lemuel A.Brown1, Kevin L. Shimkus2, Tyrone A. Washington1, Stephen F.Crouse, FACSM3, and Nicholas P.Greene123 1Human Performance Laboratory, Department of Health, Human Performance and Recreation, University of Arkansas, Fayetteville, AR, 2Muscle Biology Laboratory, Department of Health & Kinesiology, Texas A&M University, College Station, TX, 3Applied Exercise Science Laboratory, Department of Health & Kinesiology, Texas A&M University, College Station, TX

Exercise is known to stimulate muscle protein synthesis through transcription and translation of nuclear DNA leading to muscular hypertrophy and mitochondrial biogenesis. To our knowledge, the effect of exercise on mitochondrial translation has yet to be tested even though proteins coded by the mitochondria are paramount to metabolic health. PURPOSE: This investigation aims to determine if transcription factor A of the mitochondria (TFAM) and mitochondrial translation initiation factor 2 (mtIF2) protein expression is enhanced following high-volume resistance training and see if any difference exists in obesity compared to lean controls. METHODS: Zucker Rats (N=30, 16 lean, 14 obese) engaged in either a resistance training protocol or remained sedentary. The exercised rats (n = 8 lean and 8 obese) undertook a resistance exercise protocol involving a hind limb ‘squat-like’ exercise while the remainder (n=8 lean and 6 obese) were sedentary. Sixteen hours following the final bout of resistance exercise, the animals were euthanized and mixed fiber gastrocnemius muscles were removed and immediately frozen in liquid nitrogen. Samples were later analyzed for TFAM and mtIF2 protein expression via Western blot analysis. Data were analyzed using a 2x2 ANOVA (exercise vs. sedentary X lean vs. obese); α was set at p≤0.05. RESULTS: TFAM protein content increased by 54.62%(p0.05). No significant difference in TFAM and mtIF2 was observed between lean and obese responses to exercise. CONCLUSION: Resistance exercise increased the expression of mitochondrial transcription factors and appears to increase expression of mitochondrial translation factors in lean and obese animals indicating enhanced capacity for transcription and translation of mitochondrially encoded genes with high volume exercise training. These data suggest that resistance training could lead to increased metabolic proteins derived from the mitochondrial DNA in mammals. Enhanced mitochondrial protein synthesis would likely lead to increased oxidative phosphorylation enzymes such as those used in the electron transport system indicating a possible pathway for resistance training improvements on whole organism metabolic health.

This investigation was funded by the Sydney & J.L. Huffines Institue for Sports Medicine & Human Performance at Texas A&M University.

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