Cardiac Performance During Rhythmic HandgripExercise

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2288 PURPOSE:To examine cardiac performance during rhythmic handgrip exercise. METHODS: Continuous measures of arterial pressure, thoracic bio-impedance, heart sounds, and an electrocardiogram were collected in 12 participants (mean age: 26 ± 2 yr) during 5 minutes of supine rest (R), 3 minutes of rhythmic handgrip exercise (EX) and 5 minutes of supine recovery (RC). Contractions were performed at an intensity of 70% of maximal voluntary contraction and at a rate of 1 contraction every 4 seconds. The following variables were recorded and calculated during the last 10 heart beats of each condition: stroke volume (SV), heart rate (HR), cardiac output (Q), mean arterial pressure (MAP), total peripheral resistance (TPR), rate-pressure product (RPP), pre-ejection period (PEP), diastolic time (DT), left ventricular ejection time (LVET), diastolic filling rate (DFR), and left ventricular ejection rate (LVER). A repeated measures ANOVA was used to examine differences in the 10-beat average of each variable between conditions and all tests were considered significant at the 0.05 level. RESULTS: EX resulted in significant increases in MAP (82.7 ± 4 vs .106.5 ± 6 mmHg), TPR (29.2 ± 4 vs. 43.8 ± 9 mmHg·l-1·min-1), HR (58.3 ± 2 vs. 67.7 ± 2 bpm) and RPP (71.7 ± 4 vs. 99.2 ± 7 units) compared to R. EX also resulted in decreases in SV (61.3 ± 7 vs. 53.9 ± 7 ml·beat-1) and LVER (282.7 ± 35 vs. 250.9 ± 34 ml·s-1) compared to R. The aforementioned variables all returned to resting values during RC and did not differ from R. PEP only differed between EX and RC (EX: 239 ± 13; RC: 260 ± 7 ms) and DT was greater during RC (594 ± 35 ms) compared to R (493 ± 19 ms) and EX (447 ± 32 ms). CONCLUSIONS: EX resulted in an increased MAP, TPR, HR and RPP, and a reduced SV and LVER. The reduced SV during EX and it's return to baseline during RC appears to be the result of increases and decreases in afterload, respectively, as DFR was not altered during any condition.