Masters Thesis

Synchronization of step-phase and cardiac cycle during maximal treadmill testing

Diastolic Cardio-locomotor synchronization (CLS) describes the intentional timing of foot strike to occur precisely during cardiac diastole. Diastolic CLS may maximize the efficiency with which skeletal muscle promotes venous return of blood to the heart, ultimately increasing cardiac output during exercise. A recent study8 found that diastolic CLS produced lower heart rates during steady-state running compared with systolic CLS. Diastolic CLS has also been shown to improve metabolic efficiency19 and may prolong aerobic energy production during steady-state running. Currently, there are no studies on the effects o f diastolic CLS on maximal oxygen consumption (V02max). Furthermore, no studies have reported measures of perceived exertion (RPE) during CLS running. Purpose: The aim o f this study is to assess metabolic responses, heart rate, and perceived exertion to running when foot strike occurs during CLS or Natural Pace (NP) conditions. Methods: Twenty-two physically active adult participants (15 male; age 18-28 years) performed three separate treadmill V02max trials, spaced at least 7 days apart. During visit 1, participants completed baseline treadmill V02max test. During the remaining two visits, participants were blinded and randomized to either CLS or NP condition, both of which guided foot strike to an auditory metronome. During each condition, metabolic variables (VE, V02. RF- RQ, TV) and heart rate ('HR') were recorded continuously and averaged over the last 30 seconds of each two-minute stage. Rating of Perceived exertion (RPE) was recorded during the final 15-sec of each stage. Statistical Analysis: One-way analysis o f variance was used to compare V0 2 max between baseline, CLS, and NP conditions. One-way analysis of variance with repeated measures was used to compare Results: No significant differences in V0 2 ma\ were found between conditions for all participants, as well as those who met step criteria. RPE was significantly lower during CLS than NP condition during stages 5 and 6 . Ch-Pulse was significantly higher during CLS than NP condition during stage 4. No significant differences were observed in heart rate, VO2, or RER between conditions at any stage. Conclusion: Synchronization o f step phase with cardiac diastole does not improve maximal aerobic capacity during treadmill VOimax test. However, CLS does decrease perceived exertion and increase 0 2 -Pulse at submaximal intensities, suggesting unique health and performance benefits during exercise.

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