Effect of training on age-related changes in plasma insulin and glucose.

The research article investigates the impact of a 12-week exercise training program on the plasma glucose and insulin levels in young, middle-aged and old horses. It concludes that age and exercise training significantly influence these parameters.

Research Design and Methodology

• The study used 18 healthy, unfit mares divided into three age groups: young (6.8 years approximately, 6 horses), middle-aged (15.2 years approximately, 6 horses), and old (27.0 years approximately, 6 horses).
• The exercise training consisted of submaximal intensity exercise for about 30 minutes a day, 3 days a week in the first 8 weeks, and 4 days a week in the final weeks (9-12)
• Pre and post-training incremental exercise tests were done to measure the plasma glucose and insulin concentrations from immediately after exercise until 120 min post their respective exercise test.

Key Findings

• Post exercise, old mares had lower glucose levels compared to young and middle-aged mares, indicating an age-related difference in glucose regulation.
• The research also noted a time-age interaction; after 120 minutes of post-exercise test, glucose levels hadn’t returned to their pre-exercise values.
• However, the impact of the training on the acute exercise-induced glucose concentrations was non-significant across all age groups.
• Before training, old mares exhibited higher plasma insulin levels compared to their younger counterparts at the 120th-minute post-exercise mark. This elevation was also registered when compared to all other time points suggested in the 120-min exercise test.
• The training led to an increase in plasma insulin concentrations at 120 min post-exercise in all age groups – a phenomenon called rebound hyperinsulinaemia, possibly due to an increased need for glycogen replenishment in muscles.

Overall Implication of the Study

• The study emphasizes how age can influence glucose and insulin responses to acute exercise both prior to and after a 12-week exercise training program.
• Understanding these factors is crucial in assessing an older horse’s capacity to withstand exercise. Consequently, it can guide customized exercise programs for horses of different ages to ensure optimal health and well-being.