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P A Harris - One of the best experts on this subject based on the ideXlab platform.

  • glucose and insulin responses to different Dietary Energy Sources in thoroughbred broodmares grazing cool season pasture
    Livestock Science, 2007
    Co-Authors: W B Staniar, Tania A Cubitt, L A George, P A Harris, R J Geor
    Abstract:

    Abstract The objectives of this study were to characterize the glycemic and insulinemic responses of Thoroughbred broodmares fed late spring pasture only or a mixture of pasture and a high starch or low starch feed and to test hypotheses about differences in the glycemic and insulinemic effects of these Dietary regimes. A group of 15 mares were divided into three treatment groups; pasture and high starch feed (PHS), pasture and low starch feed (PLS), and pasture only (PO) and maintained in these groups for 4.5 months prior to this study. These groups were maintained on a single pasture that was temporarily divided into three sections. The study protocol was conducted over two days. On day 1 the mares were fed their respective treatments and on day 2 all mares were allowed access to pasture only. On both days plasma glucose and insulin were measured in samples taken over a 7.5 h period. Baseline measurements for glucose and insulin were not different between any of the treatment groups on either day ( P  > 0.05). The baseline insulin concentrations of these pasture-kept mares (26.7 ± 8.3 mIU/L) were high compared to those reported from stall-kept horses. Plasma glucose and insulin on day 1 were influenced by treatment group, sample time, and an interaction between treatment and time ( P P  > 0.05). Glucose and insulin rose to higher ( P P  > 0.05) detected between the PLS and PO groups. These results are reflected in greater areas under the concentration-time curves for glucose and insulin in the PHS group on day 1 ( P P  > 0.05). These results indicate a clear difference in the glycemic and insulinemic effect of the PHS feed compared to the PLS and PO groups. Of further interest are the glucose and insulin characteristics of these pasture-kept mares that indicate a low insulin sensitivity and high insulin secretory response. This study provides further information on factors influencing glycemic and insulinemic responses in horses.

  • glucose dynamics during exercise Dietary Energy Sources affect minimal model parameters in trained arabian geldings during endurance exercise
    Equine Veterinary Journal, 2006
    Co-Authors: K H Treiber, R J Geor, T M Hess, D S Kronfeld, R C Boston, M Friere, A M G B Silva, P A Harris
    Abstract:

    Summary Reasons for performing study: Glucose regulation is critical for health and exercise performance. Objectives: To quantify the effects of exercise and diet on insulin sensitivity (SI), glucose effectiveness (Sg), acute insulin response to glucose (AIRg) and disposition index (DI) in horses. Methods: This study applied the minimal model of glucose and insulin dynamics to exercise-trained Arabian geldings during rest or constant moderate-intensity exercise after 8 weeks adaptation to feeds high in sugar and starch (SS, n=6) or fat and fibre (FF, n = 6). Horses underwent 2 frequently sampled i.v. glucose tolerance tests (FSIGT). For both tests, a resting basal sample was collected, followed by an i.v. dose of 600 mg/kg bwt glucose defining 0 min of the test. Insulin (0.01 iu/kg bwt) was administered 20 min post glucose for each test. Resting horses were sampled for 240 min. The exercise FSIGT began after each horse had warmed-up for 25 min on the treadmill at which point they had reached the speed representing 60% of their predetermined lactate breakpoint maintained for the rest of the FSIGT. Exercising horses were sampled identically to rest, but for only 150 min post glucose. Results: Exercise increased (P≤0.008) SI, Sg and DI and decreased AIRg in all horses. Overall, horses adapted to FF tended to have higher SI (P=0.070) and DI (P = 0.058). During exercise, FF horses tended to have higher (P≤0.085) SI and DI, than SS horses and these variables tended to be increased more (P≤0.075) by exercise in FF horses than SS horses. Conclusions: Insulin and glucose dynamics adjust during exercise, increasing plasma glucose uptake, presumably to meet demand by contracting skeletal muscle. Trained horses adapted to a high fat diet showed greater metabolic adjustment during exercise than trained horses adapted to a high starch and sugar diet, potentially allowing them to better meet Energy demands. Potential relevance: Nutrition and exercise impact glucose and insulin dynamics, potentially influencing health and performance.

  • Dietary Energy Sources affect insulin sensitivity and β cell responsiveness of trained arabian geldings during endurance exercise
    Journal of Animal Physiology and Animal Nutrition, 2005
    Co-Authors: K H Treiber, R J Geor, T M Hess, D S Kronfeld, R C Boston, P A Harris
    Abstract:

    Adaptation to diets which replace carbohydrates with fat as an Energy source have been shown to avoid insulin resistance and improve metabolic regulation during exercise. This study compared the effects of diet and moderate-intensity exercise on glucose and insulin concentrations in 12 trained Arabian geldings. Six Arabians were adapted for 8 weeks to a feed high in sugar and starch (SS) and six were adapted to a feed rich in fat and fibre (FF). All horses were exercise-trained prior to and throughout feed adaptation. Horses were sampled between 0900 and 1000 h at rest and during moderate-intensity exercise on a treadmill at 57% of their lactate threshold following 25 min of warm-up. Plasma was analysed for glucose and insulin. Basal proxies for insulin sensitivity (LRIB = log[100/basal insulin]) and pancreatic β-cell response to circulating glucose (MIRG = log[(100·basal insulin)/(basal glucose – 50 mg/dL)]) were calculated. Basal insulin tended to be lower in FF adapted horses (p = 0.068) and was lower during exercise as compared to rest in FF horses (p = 0.013) but not SS horses (p = 0.44). Plasma glucose concentration was lower in FF horses (p < 0.001) and increased during exercise for SS adapted horses (p = 0.015) but not FF horses (p = 0.38). Insulin sensitivity as determined by LRIB was higher during exercise (p = 0.019) for all 12 horses while β-cell response as determined by MIRG was lower (p = 0.006). Arabians adapted to the FF diet also had higher LRIB (p = 0.047) but diet had no affect on MIRG (p = 0.20). Exercise tended to increase (p = 0.11) LRIB more in FF horses (34%) than SS horses (11%). These differences indicate that horses adapted to high carbohydrate diets have lower insulin sensitivity and impaired metabolic regulation involving insulin signalling. These effects are avoided in horses adapted to the FF feed, with potential benefits to their health and endurance exercise performance.

K H Treiber - One of the best experts on this subject based on the ideXlab platform.

  • glucose dynamics during exercise Dietary Energy Sources affect minimal model parameters in trained arabian geldings during endurance exercise
    Equine Veterinary Journal, 2006
    Co-Authors: K H Treiber, R J Geor, T M Hess, D S Kronfeld, R C Boston, M Friere, A M G B Silva, P A Harris
    Abstract:

    Summary Reasons for performing study: Glucose regulation is critical for health and exercise performance. Objectives: To quantify the effects of exercise and diet on insulin sensitivity (SI), glucose effectiveness (Sg), acute insulin response to glucose (AIRg) and disposition index (DI) in horses. Methods: This study applied the minimal model of glucose and insulin dynamics to exercise-trained Arabian geldings during rest or constant moderate-intensity exercise after 8 weeks adaptation to feeds high in sugar and starch (SS, n=6) or fat and fibre (FF, n = 6). Horses underwent 2 frequently sampled i.v. glucose tolerance tests (FSIGT). For both tests, a resting basal sample was collected, followed by an i.v. dose of 600 mg/kg bwt glucose defining 0 min of the test. Insulin (0.01 iu/kg bwt) was administered 20 min post glucose for each test. Resting horses were sampled for 240 min. The exercise FSIGT began after each horse had warmed-up for 25 min on the treadmill at which point they had reached the speed representing 60% of their predetermined lactate breakpoint maintained for the rest of the FSIGT. Exercising horses were sampled identically to rest, but for only 150 min post glucose. Results: Exercise increased (P≤0.008) SI, Sg and DI and decreased AIRg in all horses. Overall, horses adapted to FF tended to have higher SI (P=0.070) and DI (P = 0.058). During exercise, FF horses tended to have higher (P≤0.085) SI and DI, than SS horses and these variables tended to be increased more (P≤0.075) by exercise in FF horses than SS horses. Conclusions: Insulin and glucose dynamics adjust during exercise, increasing plasma glucose uptake, presumably to meet demand by contracting skeletal muscle. Trained horses adapted to a high fat diet showed greater metabolic adjustment during exercise than trained horses adapted to a high starch and sugar diet, potentially allowing them to better meet Energy demands. Potential relevance: Nutrition and exercise impact glucose and insulin dynamics, potentially influencing health and performance.

  • Dietary Energy Sources affect insulin sensitivity and β cell responsiveness of trained arabian geldings during endurance exercise
    Journal of Animal Physiology and Animal Nutrition, 2005
    Co-Authors: K H Treiber, R J Geor, T M Hess, D S Kronfeld, R C Boston, P A Harris
    Abstract:

    Adaptation to diets which replace carbohydrates with fat as an Energy source have been shown to avoid insulin resistance and improve metabolic regulation during exercise. This study compared the effects of diet and moderate-intensity exercise on glucose and insulin concentrations in 12 trained Arabian geldings. Six Arabians were adapted for 8 weeks to a feed high in sugar and starch (SS) and six were adapted to a feed rich in fat and fibre (FF). All horses were exercise-trained prior to and throughout feed adaptation. Horses were sampled between 0900 and 1000 h at rest and during moderate-intensity exercise on a treadmill at 57% of their lactate threshold following 25 min of warm-up. Plasma was analysed for glucose and insulin. Basal proxies for insulin sensitivity (LRIB = log[100/basal insulin]) and pancreatic β-cell response to circulating glucose (MIRG = log[(100·basal insulin)/(basal glucose – 50 mg/dL)]) were calculated. Basal insulin tended to be lower in FF adapted horses (p = 0.068) and was lower during exercise as compared to rest in FF horses (p = 0.013) but not SS horses (p = 0.44). Plasma glucose concentration was lower in FF horses (p < 0.001) and increased during exercise for SS adapted horses (p = 0.015) but not FF horses (p = 0.38). Insulin sensitivity as determined by LRIB was higher during exercise (p = 0.019) for all 12 horses while β-cell response as determined by MIRG was lower (p = 0.006). Arabians adapted to the FF diet also had higher LRIB (p = 0.047) but diet had no affect on MIRG (p = 0.20). Exercise tended to increase (p = 0.11) LRIB more in FF horses (34%) than SS horses (11%). These differences indicate that horses adapted to high carbohydrate diets have lower insulin sensitivity and impaired metabolic regulation involving insulin signalling. These effects are avoided in horses adapted to the FF feed, with potential benefits to their health and endurance exercise performance.

R J Geor - One of the best experts on this subject based on the ideXlab platform.

  • glucose and insulin responses to different Dietary Energy Sources in thoroughbred broodmares grazing cool season pasture
    Livestock Science, 2007
    Co-Authors: W B Staniar, Tania A Cubitt, L A George, P A Harris, R J Geor
    Abstract:

    Abstract The objectives of this study were to characterize the glycemic and insulinemic responses of Thoroughbred broodmares fed late spring pasture only or a mixture of pasture and a high starch or low starch feed and to test hypotheses about differences in the glycemic and insulinemic effects of these Dietary regimes. A group of 15 mares were divided into three treatment groups; pasture and high starch feed (PHS), pasture and low starch feed (PLS), and pasture only (PO) and maintained in these groups for 4.5 months prior to this study. These groups were maintained on a single pasture that was temporarily divided into three sections. The study protocol was conducted over two days. On day 1 the mares were fed their respective treatments and on day 2 all mares were allowed access to pasture only. On both days plasma glucose and insulin were measured in samples taken over a 7.5 h period. Baseline measurements for glucose and insulin were not different between any of the treatment groups on either day ( P  > 0.05). The baseline insulin concentrations of these pasture-kept mares (26.7 ± 8.3 mIU/L) were high compared to those reported from stall-kept horses. Plasma glucose and insulin on day 1 were influenced by treatment group, sample time, and an interaction between treatment and time ( P P  > 0.05). Glucose and insulin rose to higher ( P P  > 0.05) detected between the PLS and PO groups. These results are reflected in greater areas under the concentration-time curves for glucose and insulin in the PHS group on day 1 ( P P  > 0.05). These results indicate a clear difference in the glycemic and insulinemic effect of the PHS feed compared to the PLS and PO groups. Of further interest are the glucose and insulin characteristics of these pasture-kept mares that indicate a low insulin sensitivity and high insulin secretory response. This study provides further information on factors influencing glycemic and insulinemic responses in horses.

  • glucose dynamics during exercise Dietary Energy Sources affect minimal model parameters in trained arabian geldings during endurance exercise
    Equine Veterinary Journal, 2006
    Co-Authors: K H Treiber, R J Geor, T M Hess, D S Kronfeld, R C Boston, M Friere, A M G B Silva, P A Harris
    Abstract:

    Summary Reasons for performing study: Glucose regulation is critical for health and exercise performance. Objectives: To quantify the effects of exercise and diet on insulin sensitivity (SI), glucose effectiveness (Sg), acute insulin response to glucose (AIRg) and disposition index (DI) in horses. Methods: This study applied the minimal model of glucose and insulin dynamics to exercise-trained Arabian geldings during rest or constant moderate-intensity exercise after 8 weeks adaptation to feeds high in sugar and starch (SS, n=6) or fat and fibre (FF, n = 6). Horses underwent 2 frequently sampled i.v. glucose tolerance tests (FSIGT). For both tests, a resting basal sample was collected, followed by an i.v. dose of 600 mg/kg bwt glucose defining 0 min of the test. Insulin (0.01 iu/kg bwt) was administered 20 min post glucose for each test. Resting horses were sampled for 240 min. The exercise FSIGT began after each horse had warmed-up for 25 min on the treadmill at which point they had reached the speed representing 60% of their predetermined lactate breakpoint maintained for the rest of the FSIGT. Exercising horses were sampled identically to rest, but for only 150 min post glucose. Results: Exercise increased (P≤0.008) SI, Sg and DI and decreased AIRg in all horses. Overall, horses adapted to FF tended to have higher SI (P=0.070) and DI (P = 0.058). During exercise, FF horses tended to have higher (P≤0.085) SI and DI, than SS horses and these variables tended to be increased more (P≤0.075) by exercise in FF horses than SS horses. Conclusions: Insulin and glucose dynamics adjust during exercise, increasing plasma glucose uptake, presumably to meet demand by contracting skeletal muscle. Trained horses adapted to a high fat diet showed greater metabolic adjustment during exercise than trained horses adapted to a high starch and sugar diet, potentially allowing them to better meet Energy demands. Potential relevance: Nutrition and exercise impact glucose and insulin dynamics, potentially influencing health and performance.

  • Dietary Energy Sources affect insulin sensitivity and β cell responsiveness of trained arabian geldings during endurance exercise
    Journal of Animal Physiology and Animal Nutrition, 2005
    Co-Authors: K H Treiber, R J Geor, T M Hess, D S Kronfeld, R C Boston, P A Harris
    Abstract:

    Adaptation to diets which replace carbohydrates with fat as an Energy source have been shown to avoid insulin resistance and improve metabolic regulation during exercise. This study compared the effects of diet and moderate-intensity exercise on glucose and insulin concentrations in 12 trained Arabian geldings. Six Arabians were adapted for 8 weeks to a feed high in sugar and starch (SS) and six were adapted to a feed rich in fat and fibre (FF). All horses were exercise-trained prior to and throughout feed adaptation. Horses were sampled between 0900 and 1000 h at rest and during moderate-intensity exercise on a treadmill at 57% of their lactate threshold following 25 min of warm-up. Plasma was analysed for glucose and insulin. Basal proxies for insulin sensitivity (LRIB = log[100/basal insulin]) and pancreatic β-cell response to circulating glucose (MIRG = log[(100·basal insulin)/(basal glucose – 50 mg/dL)]) were calculated. Basal insulin tended to be lower in FF adapted horses (p = 0.068) and was lower during exercise as compared to rest in FF horses (p = 0.013) but not SS horses (p = 0.44). Plasma glucose concentration was lower in FF horses (p < 0.001) and increased during exercise for SS adapted horses (p = 0.015) but not FF horses (p = 0.38). Insulin sensitivity as determined by LRIB was higher during exercise (p = 0.019) for all 12 horses while β-cell response as determined by MIRG was lower (p = 0.006). Arabians adapted to the FF diet also had higher LRIB (p = 0.047) but diet had no affect on MIRG (p = 0.20). Exercise tended to increase (p = 0.11) LRIB more in FF horses (34%) than SS horses (11%). These differences indicate that horses adapted to high carbohydrate diets have lower insulin sensitivity and impaired metabolic regulation involving insulin signalling. These effects are avoided in horses adapted to the FF feed, with potential benefits to their health and endurance exercise performance.

R C Boston - One of the best experts on this subject based on the ideXlab platform.

  • glucose dynamics during exercise Dietary Energy Sources affect minimal model parameters in trained arabian geldings during endurance exercise
    Equine Veterinary Journal, 2006
    Co-Authors: K H Treiber, R J Geor, T M Hess, D S Kronfeld, R C Boston, M Friere, A M G B Silva, P A Harris
    Abstract:

    Summary Reasons for performing study: Glucose regulation is critical for health and exercise performance. Objectives: To quantify the effects of exercise and diet on insulin sensitivity (SI), glucose effectiveness (Sg), acute insulin response to glucose (AIRg) and disposition index (DI) in horses. Methods: This study applied the minimal model of glucose and insulin dynamics to exercise-trained Arabian geldings during rest or constant moderate-intensity exercise after 8 weeks adaptation to feeds high in sugar and starch (SS, n=6) or fat and fibre (FF, n = 6). Horses underwent 2 frequently sampled i.v. glucose tolerance tests (FSIGT). For both tests, a resting basal sample was collected, followed by an i.v. dose of 600 mg/kg bwt glucose defining 0 min of the test. Insulin (0.01 iu/kg bwt) was administered 20 min post glucose for each test. Resting horses were sampled for 240 min. The exercise FSIGT began after each horse had warmed-up for 25 min on the treadmill at which point they had reached the speed representing 60% of their predetermined lactate breakpoint maintained for the rest of the FSIGT. Exercising horses were sampled identically to rest, but for only 150 min post glucose. Results: Exercise increased (P≤0.008) SI, Sg and DI and decreased AIRg in all horses. Overall, horses adapted to FF tended to have higher SI (P=0.070) and DI (P = 0.058). During exercise, FF horses tended to have higher (P≤0.085) SI and DI, than SS horses and these variables tended to be increased more (P≤0.075) by exercise in FF horses than SS horses. Conclusions: Insulin and glucose dynamics adjust during exercise, increasing plasma glucose uptake, presumably to meet demand by contracting skeletal muscle. Trained horses adapted to a high fat diet showed greater metabolic adjustment during exercise than trained horses adapted to a high starch and sugar diet, potentially allowing them to better meet Energy demands. Potential relevance: Nutrition and exercise impact glucose and insulin dynamics, potentially influencing health and performance.

  • Dietary Energy Sources affect insulin sensitivity and β cell responsiveness of trained arabian geldings during endurance exercise
    Journal of Animal Physiology and Animal Nutrition, 2005
    Co-Authors: K H Treiber, R J Geor, T M Hess, D S Kronfeld, R C Boston, P A Harris
    Abstract:

    Adaptation to diets which replace carbohydrates with fat as an Energy source have been shown to avoid insulin resistance and improve metabolic regulation during exercise. This study compared the effects of diet and moderate-intensity exercise on glucose and insulin concentrations in 12 trained Arabian geldings. Six Arabians were adapted for 8 weeks to a feed high in sugar and starch (SS) and six were adapted to a feed rich in fat and fibre (FF). All horses were exercise-trained prior to and throughout feed adaptation. Horses were sampled between 0900 and 1000 h at rest and during moderate-intensity exercise on a treadmill at 57% of their lactate threshold following 25 min of warm-up. Plasma was analysed for glucose and insulin. Basal proxies for insulin sensitivity (LRIB = log[100/basal insulin]) and pancreatic β-cell response to circulating glucose (MIRG = log[(100·basal insulin)/(basal glucose – 50 mg/dL)]) were calculated. Basal insulin tended to be lower in FF adapted horses (p = 0.068) and was lower during exercise as compared to rest in FF horses (p = 0.013) but not SS horses (p = 0.44). Plasma glucose concentration was lower in FF horses (p < 0.001) and increased during exercise for SS adapted horses (p = 0.015) but not FF horses (p = 0.38). Insulin sensitivity as determined by LRIB was higher during exercise (p = 0.019) for all 12 horses while β-cell response as determined by MIRG was lower (p = 0.006). Arabians adapted to the FF diet also had higher LRIB (p = 0.047) but diet had no affect on MIRG (p = 0.20). Exercise tended to increase (p = 0.11) LRIB more in FF horses (34%) than SS horses (11%). These differences indicate that horses adapted to high carbohydrate diets have lower insulin sensitivity and impaired metabolic regulation involving insulin signalling. These effects are avoided in horses adapted to the FF feed, with potential benefits to their health and endurance exercise performance.

D S Kronfeld - One of the best experts on this subject based on the ideXlab platform.

  • glucose dynamics during exercise Dietary Energy Sources affect minimal model parameters in trained arabian geldings during endurance exercise
    Equine Veterinary Journal, 2006
    Co-Authors: K H Treiber, R J Geor, T M Hess, D S Kronfeld, R C Boston, M Friere, A M G B Silva, P A Harris
    Abstract:

    Summary Reasons for performing study: Glucose regulation is critical for health and exercise performance. Objectives: To quantify the effects of exercise and diet on insulin sensitivity (SI), glucose effectiveness (Sg), acute insulin response to glucose (AIRg) and disposition index (DI) in horses. Methods: This study applied the minimal model of glucose and insulin dynamics to exercise-trained Arabian geldings during rest or constant moderate-intensity exercise after 8 weeks adaptation to feeds high in sugar and starch (SS, n=6) or fat and fibre (FF, n = 6). Horses underwent 2 frequently sampled i.v. glucose tolerance tests (FSIGT). For both tests, a resting basal sample was collected, followed by an i.v. dose of 600 mg/kg bwt glucose defining 0 min of the test. Insulin (0.01 iu/kg bwt) was administered 20 min post glucose for each test. Resting horses were sampled for 240 min. The exercise FSIGT began after each horse had warmed-up for 25 min on the treadmill at which point they had reached the speed representing 60% of their predetermined lactate breakpoint maintained for the rest of the FSIGT. Exercising horses were sampled identically to rest, but for only 150 min post glucose. Results: Exercise increased (P≤0.008) SI, Sg and DI and decreased AIRg in all horses. Overall, horses adapted to FF tended to have higher SI (P=0.070) and DI (P = 0.058). During exercise, FF horses tended to have higher (P≤0.085) SI and DI, than SS horses and these variables tended to be increased more (P≤0.075) by exercise in FF horses than SS horses. Conclusions: Insulin and glucose dynamics adjust during exercise, increasing plasma glucose uptake, presumably to meet demand by contracting skeletal muscle. Trained horses adapted to a high fat diet showed greater metabolic adjustment during exercise than trained horses adapted to a high starch and sugar diet, potentially allowing them to better meet Energy demands. Potential relevance: Nutrition and exercise impact glucose and insulin dynamics, potentially influencing health and performance.

  • Dietary Energy Sources affect insulin sensitivity and β cell responsiveness of trained arabian geldings during endurance exercise
    Journal of Animal Physiology and Animal Nutrition, 2005
    Co-Authors: K H Treiber, R J Geor, T M Hess, D S Kronfeld, R C Boston, P A Harris
    Abstract:

    Adaptation to diets which replace carbohydrates with fat as an Energy source have been shown to avoid insulin resistance and improve metabolic regulation during exercise. This study compared the effects of diet and moderate-intensity exercise on glucose and insulin concentrations in 12 trained Arabian geldings. Six Arabians were adapted for 8 weeks to a feed high in sugar and starch (SS) and six were adapted to a feed rich in fat and fibre (FF). All horses were exercise-trained prior to and throughout feed adaptation. Horses were sampled between 0900 and 1000 h at rest and during moderate-intensity exercise on a treadmill at 57% of their lactate threshold following 25 min of warm-up. Plasma was analysed for glucose and insulin. Basal proxies for insulin sensitivity (LRIB = log[100/basal insulin]) and pancreatic β-cell response to circulating glucose (MIRG = log[(100·basal insulin)/(basal glucose – 50 mg/dL)]) were calculated. Basal insulin tended to be lower in FF adapted horses (p = 0.068) and was lower during exercise as compared to rest in FF horses (p = 0.013) but not SS horses (p = 0.44). Plasma glucose concentration was lower in FF horses (p < 0.001) and increased during exercise for SS adapted horses (p = 0.015) but not FF horses (p = 0.38). Insulin sensitivity as determined by LRIB was higher during exercise (p = 0.019) for all 12 horses while β-cell response as determined by MIRG was lower (p = 0.006). Arabians adapted to the FF diet also had higher LRIB (p = 0.047) but diet had no affect on MIRG (p = 0.20). Exercise tended to increase (p = 0.11) LRIB more in FF horses (34%) than SS horses (11%). These differences indicate that horses adapted to high carbohydrate diets have lower insulin sensitivity and impaired metabolic regulation involving insulin signalling. These effects are avoided in horses adapted to the FF feed, with potential benefits to their health and endurance exercise performance.