The effect of intensive training and β-hydroxy-β-methylbutyrate (HMB) on the physiological response to exercise in horses
Date
1998
Authors
Sandberg, JoAnn Liv
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Miller, Peggy
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Abstract
[Beta]-hydroxy-[Beta]-methylbutyrate (HMB) is a leucine metabolite that has been shown to enhance muscle strength and endurance. This study evaluated the physiological responses of exercising horses fed HMB. Five geldings were fed a control supplement containing ground limestone and 5 geldings were fed the same supplement substituting HMB (@ approx. 1g CaHMB/45.5 kg BW) for the limestone. The horses were exercised 4X/week on a highspeed treadmill for 12 weeks; the first 6 weeks consisted of light to moderate work followed by 6 weeks of high intensity work. All horses performed a standard exercise test (SET) prior to conditioning with repeated SET at 6 weeks and 12 weeks. The SET consisted of 10 mins at a heart rate (HR) of 160, 2 mins @ HR 200, 10 mins @ HR 160, 2 mins @ HR 200, and a 60 min recovery period.
Conditioning allowed another 10 min of exercise @ HR of 160 immediately prior to recovery. Conditioning did not (P>.05) effect velocity. HMB treatment did not (P>.05) effect velocity. Conditioning decreased (P<.001) plasma triglyceride concentrations; however, HMB treatment did not (P>.05) effect plasma triglycerides. Glucose concentration increased with exercise during each SET and increased (P<.OOO1) in response to conditioning. HMB treatment did not (P>.05) effect blood glucose concentrations. Plasma lactate concentration decreased (P<.OOO1) with conditioning; however, there was no (P>.05) effect of dietary HMB supplementation on plasma lactate concentration. Muscle glycogen decreased (P<.OOO1) following exercise.
Muscle glycogen was not (P>.05) effected by conditioning or HMB supplementation. Aerobic conditioning increased oxidative metabolism but the addition of anaerobic training during the last 6 weeks did not effect lactate levels. In conclusion, aerobic conditioning appeared to benefit the horse, with no additional benefit noted following anaerobic conditioning. Dietary HMB did not effect the parameters measured in this study.
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thesis