Electronic Thesis and Dissertation Repository


Master of Science




Dr. Charles Rice


PURPOSE: The aim of the current study was to examine the effect on electromechanical delay (EMD) in the dorsiflexors of young and old women during maximal isometric voluntary and electrically evoked contractions, and after a bout of lengthening contractions. METHODS: Nine young (25.1±1.3 years) and nine old (68.3±6.1 years) women performed baseline isometric contractions with evoked twitches followed by a series of dynamic lengthening contractions using a Biodex multi-joint dynamometer. Maximal isometric voluntary and evoked contractions were measured to assess EMD. Time points were recorded at baseline, mid-point of the intervention, post-task termination, and during recovery at 0.5, 2, 10, and 30 minutes. RESULTS: The EMD of the evoked twitches and voluntary contractions were not different in the young and old at baseline. Following the lengthening contractions the EMD of the evoked contractions at the midpoint of fatigue were shorter in the young compared to old, but not different between groups at task termination, or during recovery. No differences in the EMD measured from the voluntary maximal isometric contractions in the young and old at any fatigue or recovery time points. CONCLUSION: Shorter evoked EMD in the young during the midpoint of the intervention was possibly a result of potentiation which dissipated by task-termination as fatigue developed. This did not occur in old women. Results indicate that in the dorsiflexors EMD is not affected by age in women and overall is not affected by fatigue in either group. Recovery in both measures of EMD was not differently affected by age.