An investigation of the Morganroth hypothesis to establish if heart adaptation is exercise specific
AuthorsRichards, Joanna C.
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AbstractThe investigation of exercise specific left ventricular (LV) adaptations to training have been predominantly cross sectional in design. The purpose of the current thesis was to investigate LV adaptations to short term (6-9 weeks) training to establish if any changes are exercise specific. A correlation study was used to investigate correlations between cardiac variables and MAXOV2(study 1). Cardiac variables were found to be the strongest predictors for absolute MAXOV2, MAXOV2BM and MAXOV2FFM in cyclists compared to the total sample or sedentary group, predicting 79% (p<0.01), 70% (p<0.01) and 77% (p<0.01) of the variance, respectively. Secondly, it was found that when MAXOV2 was scaled to body mass (BM) or fat free mass (FFM) cardiac variables predicted less of the variance than for absolute MAXOV2, for all groups. Study 2 investigated the hypothesis that there would be no evidence of LV hypertrophy when there was no increase in FFM. This was achieved by taking sedentary participants through a resistance training programme of 6 weeks duration to control for increases in skeletal muscle hypertrophy. Both resting systolic blood pressure (sBP; p = 0.01, d = 1.19) and diastolic blood pressure (dBP; p = 0.029, d = 0.88) were significantly reduced following the 6 weeks resistance training. One repetition maximum (1RM) bench press significantly increased (p = 0.00, d = -1.44) as did 1 RM parallel squat strength (p = 0.00, d = -1.86), with no associated increases in relative FFM (p = 0.45) or absolute LM (p = 0.87). There was no adaptation to LV morphology (p>0.05), however early diastolic function changed with a significant decrease in peak E wave (p = 0.00, d = 1.94). Study 3 compared differences in the time course of the initial adaptations to LV structure and function during 9 weeks of aerobic, resistance and combination exercise ii training, to establish whether LV adaptations are exercise specific. The resistance and combination groups demonstrated increases in relative wall thickness (p = 0.021, ηp2 = 0.408; p = 0.004, d = -1.06, respectively). PWd also significantly increased in the combination group (p = 0.032, ηp2 = 0.301); however there were no structural adaptations evident in the aerobic group (p > 0.05). In contrast, the aerobic group demonstrated functional adaptations with a decrease in A wave (p = 0.44, d = 0.87) as did the combination group (p = 0.002, ηp2 = 0.407). The results of the training studies showed limited support for the Morganroth Hypothesis as structural adaptations demonstrated LV remodelling of the myocardial tissue, with no increase in LV mass. Further to this, combination training appears to have an additive effect of LV adaptations of both aerobic and resistance training.
CitationRichards, J.C. (2012) 'An investigation of the Morganroth hypothesis to establish if heart adaptation is exercise specific'. PhD Thesis. University of Bedfordhire.
PublisherUniversity of Bedfordshire
TypeThesis or dissertation
DescriptionA thesis submitted to the University of Bedfordshire in partial fulfilment of the requirements for the degree of Doctor of Philosophy
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