The Impact Of Target Heart Rate Adherence on Longitudinal Change in VO2 Max in a 12-Week Exercise Program

Research Objectives: To investigate the impact of exercise intervention for older adults by examining the correlation between the change in VO₂ max and adherence to the prescribed heart rate intensity during each session of a 12-week intervention.

Design: Randomized controlled trial

Setting: Exercise physiology lab at the Atlanta VA

Participants: 28 previously sedentary older adults aged 65-89.

Interventions: 28 previously sedentary older adults (aged 65-89) completed the 12 week exercise intervention, engaging in exercise 3 times weekly following randomization into an aerobic “spin” group or a non-aerobic, stretching and balance control group. Participants wore FT7 Polar Heart Rate Monitors to track adherence to prescribed target heart rate. VO2 max was measured pre and post-intervention. Both the aerobic and non-aerobic groups began the intervention with 20-minute sessions. The time increased approximately 1-2 minutes over the course of the twelve weeks to a maximum time of 45 minutes. The aerobic spin group target heart rate began at 50% intensity and increased 5% every week to a maximum of 75% target intensity. The non-aerobic balance group’s heart rates were monitored and aimed to keep participants under the 50% aerobic threshold. Due to attrition or error, the VO₂ max for only 15 individuals was reported.

Main Outcome Measures: VO₂ max pre and post 12 week intervention, heart rate measurements every five minutes for each session of the 3 times weekly 12 week intervention, and attendance.

Results: Correlating VO₂ max to aerobic adherence within-session showed a positive relationship, with those most aerobically adherent in the “spin” group showing the greatest improvement in VO₂ max (avg change +21%). Adherence as measured by attendance showed no relationship to change in VO₂ max.

Conclusions: Because session attendance alone may underestimate physiological improvements, tracking aerobic exercise adherence using physiological measures (e.g. heart rate) is critical for determining the success of exercise interventions and improvements in VO₂ max in older adults.

Author(s) Disclosures: This material is based upon work supported by the Department of Veterans Affairs, Veterans Health Administration, Office of Research and Development Rehabilitation Research and Development Service. Publications or presentations must include a disclaimer stating that the contents do not represent the views of the Department of Veterans Affairs or the United States Government.