Author and graduation date: Linda Ann NEBEL, July, 1997

Committee members: Larry Verity (Chair), Patricia Patterson, Karen Sena

Thesis title: Differences in Work Capacity and Exercise Duration Between Four Specific Cardiac Condition Groups

The purpose of this study was to examine the potential difference in submaximal work capacity and exercise duration across four different cardiac condition groups as the result of a 12-week exercise program. Retrospectively, 80 total subjects met the inclusion criteria and were used for this study. Patient medical and exercise records from 1990-1995 were obtained from the Sharp Memorial Cardiac Rehabilitation Program.

Subjects were classified into one of the four cardiac condition groups according to their medical record: Group l (MI/TxMEd), Group 2 (MI/CABG), Group 3 (Qvfl/PTCA), or Group 4 (CABG). Previously collected data, including mile time, exercise duration, body weight, height, and risk factors, were used for this study. The subjects exercised at a submaximal. intensity equivalent to 60-70% of predicted maximum heart rate.

Work capacity was measured by a one-mile walk test administered on an outdoor track. From the mile time, the subject's MET capacity at 60-70% of predicted maximum heart rate was calculated according to the ACSM outdoor walking MET calculation, A work capacity measurement was performed within the first month of training (MET 1). Work capacity measurements were taken following two (MET 2) and three (MET 3) months of training, respectively.

Exercise duration was taken from the exercise logs one day prior to and after the day the mile time was performed. These two exercise durations were averaged and recorded as Duration 1 (DUR 1). Exercise duration was recorded at the same time interval as work capacity measurements were made and recorded as Duration 2 (DUR 2) and Duration 3 (DUR 3) .

A 4 x 3 (Group x Time) repeated measures ANOVA was used to determine whether significant differences in submaximal work capacity and exercise duration existed between the four cardiac conditions. Results for MET indicated a nonsignificant group effect (F3,76 = 2.06; p >0.10), a significant time effect (F2,152=72.57; p <. 10), and a significant interaction (F6,152 = 2.12; p <. 10). However, post-hoc analysis using Scheffe failed to locate the significant interaction.

The one-way ANOVA for percentage of change in work capacity indicated a significant difference between the groups (F1,7 = 2.93; R <0.039). Post-hoc analysis using the Tukey procedure demonstrated a significant difference between Group 2 (M:I/CABG) and Group 4 (CABG only) and between Group 3 (MI/PTCA) and Group 4 (CABG only), with Group 4 being superior to both Group 2 and Group 3.

The 4 x 3 repeated measures ANOVA for exercise duration indicated a nonsignificant group effect, (F3,76 = .22; p >.10), a significant time effect (F2,152 = 73.53; p <.10), and a nonsignificant interaction (F6,152 = .60; p >.10). A post-hoc analysis using Tukey procedure for time indicated that all pairwise comparisons were significant, with DUR 3 being superior to both DUR 2 and DUR 1 and DUR 2 being greater than DUR 1. The one-way ANOVA for percentage of change in exercise duration demonstrated a nonsignificant difference between the groups (F3,76 = .79; p >0.50) .

These results indicated that all groups benefited from the exercise training with improvements in work capacity and exercise duration. The significant difference between Group 2 and Group 4 and between Group 3 and Group 4 for percentage of change in work capacity also suggested that the groups may respond differently to the same exercise training program. Group 4 (CABG only) had a significantly greater percentage of change in work capacity than Group 2 (MI/CABG) and Group 3 QAI/PTCA) as the result of training. The results suggested that regardless of cardiac condition, all groups benefited from the exercise training. However, potential differences in the magnitude of change in work capacity may exist between the four specific cardiac condition groups. Additional research is necessary to further investigate potential differences that will advance the rehabilitation of the cardiac patient.

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