Erin E. Kelly

Cardiac autonomic modulation during recovery from acute endurance versus resistance exercise

BACKGROUND The kinetics of parasympathetic reactivation after dynamic endurance exercise have been well elucidated. However, autonomic recovery of cardiac function after resistance exercise is not known. PURPOSE The purpose of this study was to assess cardiac autonomic modulations during recovery from acute resistance exercise versus acute endurance exercise. METHODS Electrocardiogram readings were collected before and 30 min after a single bout of endurance or resistance exercise in 14 male participants (aged 25.3+/-2.5 years). Heart rate (HR) variability was spectrally decomposed using an autoregressive approach. High frequency (HF) power was considered representative of vagal modulation. All values were expressed in both absolute and normalized units (normalized for change in total power). RESULTS A mode-by-time interaction (P<0.05) was detected for HR, which remained elevated to a greater extent after resistance exercise. Total power was significantly reduced after resistance exercise (P<0.05) but not endurance exercise. An interaction (P<0.05) was also detected for both a change in absolute natural log function HF power and natural log function low frequency (LF) power (P<0.05), as both variables decreased more after resistance exercise. When normalized for changes in total power, interactions in LF and HF power were lost. The LF/HF ratio was significantly increased after both resistance and endurance exercise (P<0.05). CONCLUSION Greater elevations in HR after acute resistance exercise versus acute endurance exercise may be related to greater reductions in cardiac parasympathetic tone.

Changes in Arterial Distensibility and Flow-Mediated Dilation After Acute Resistance vs. Aerobic Exercise

Collier, SR, Diggle, MD, Heffernan, KS, Kelly, EE, Tobin, MM, and Fernhall, B. Changes in arterial distensibility and flow-mediated dilation after acute resistance vs. aerobic exercise. J Strength Cond Res 24(10): 2846-2852, 2010-Previous research has shown significantly lower arterial distensibility (AD) after resistance exercise (RE) yet higher AD after aerobic exercise (AE). These changes may be related to exercise-induced differences in vasodilatory capacity. The purpose of this study was to investigate the vasodilatory and AD responses to acute AE and RE. Forearm blood flow (FBF) during reactive hyperemia (RH) was assessed before and 60 minutes after exercise, whereas aortic and femoral pulse wave velocity was measured as an index of arterial stiffness pre, 40, and 60 minutes after an acute bout of AE (30-minute leg ergometry at 65% of &OV0312;o2peak) and RE (3 sets, 10 reps; upper and lower body at 65% 1 repetition maximum) in 10 male subjects (24.9 ± 0.86 years). Area under the curve (AUC) was employed to determine differences in flow. After the intervention, we found that central pulse wave velocity decreased 8% after AE and remained depressed at this level through 60 minutes of observation, whereas RE increased central pulse wave velocity 9.8% from pre to 40 and 60 minutes postexercise. Area under the curve for FBF-RH significantly increased 38% after RE, yet there was no significant change after AE. Forearm vasodilatory capacity increased after acute RE but not after acute AE. This suggests that changes in AD may be disassociated from changes in vasodilatory capacity after acute exercise. Further, in a direct comparison of RE vs. AE, we have shown that RE has greater increases in limb blood flow and augments postexercise hypotension greater at 40 minutes postexercise when compared to AE.

An exploratory study of cardiac function and oxygen uptake during cycle ergometry in overweight children

Objective: Obesity has been proposed to negatively impact cardiac function in overweight (OW) individuals. The relationship between diastolic dysfunction and oxygen uptake (V̇o2) kinetics is equivocal. This exploratory investigation evaluated the relationship between resting left ventricular function and V̇o2 kinetics during cycle ergometry in OW and non‐overweight (NO) children and adolescents.