Original Research
Effects of β-Hydroxy-β-Methylbutyrate and γ-Oryzanol on Blood Biochemical Markers in Exercising Thoroughbred Race Horses

https://doi.org/10.1016/j.jevs.2012.01.002Get rights and content

Abstract

In both the horse and the man, nutritional ergogenic aids have been used to improve physical ability in conjunction with an appropriate training regimen. Although training increases physical condition, the ease of taking a nutritional additive to improve training results explains the demand for supplementation, which may increase mechanical energy of work, delay onset of fatigue, or improve neuromuscular coordination. The purpose of this study was to determine the effects of oral supplementation of β-hydroxy-β-methylbutyrate (HMB) and γ-oryzanol (GO) on indices of exercise-induced muscle damage in Thoroughbred race horses. In this 32-week study, the horses were assigned to either a placebo, GO (3.0 g/d), HMB (15 g/d), or GO and HMB treatment groups. The supplements were administered for the first 16 weeks of the study during the training period before the racing season began. Blood samples were taken at baseline, and then during training, before exercise, immediately after exercise, and 30 minutes after exercise. Heart rate and speed were monitored in each exercise session. Hematocrit, glucose, lactate (LA), creatine phosphokinase, and aspartate aminotransferase were measured before and after each exercise session. Analysis of variance showed a significantly greater increase in postexercise creatine kinase activity in placebo-supplemented group than in the other treatment groups, both in the training period and during the racing seasons (P < .05). Blood LA was higher immediately after exercise in the placebo group compared with the supplemented groups. In conclusion, supplementation with HMB and GO resulted in decreased creatine kinase and LA after exercise. These findings support the hypothesis that HMB and GO supplementation helps to prevent exercise-induced muscle damage.

Introduction

β-Hydroxy-β-methylbutyrate (HMB) and γ-oryzanol (GO) are supplements used to enhance the effects of training in exercising humans, dogs, and horses. A metabolite of the amino acid leucine, HMB is produced endogenously in small amounts and has been shown to improve gains in strength and lean body mass in humans when associated with resistance training [1], [2]. The efficacy of HMB has been demonstrated in pathological conditions, where it has been reported to reduce muscle wasting associated with AIDS, trauma, and cancer cachexia [3], [4], [5]. More recently, HMB has been shown to decrease protein degradation and increase protein synthesis [6]. In decreasing muscle damage, HMB may also provide a source of cytosolic HMG-coenzyme A for cholesterol synthesis and increase the availability of cholesterol for cell membrane synthesis. This may result in an overall reinforcement of the sarcolemma as well as the provision of valuable substrate for its repair following muscle damage or injurious exercise [7]. This is evidenced by studies demonstrating that HMB leads to decreased markers of muscle damage following mechanically strenuous exercise, including lower activity of creatine kinase (CK), lactate dehydrogenase, and a decrease in muscle protein breakdown as indicated by serum 3-methylhistidine, a direct marker of muscle protein degradation [8], [9], [10]. Other studies have shown that HMB reduces cancer-induced muscle weight loss through attenuation of the ubiquitin-proteasome proteolytic pathway [11], suggesting that HMB functions predominantly as an anticatabolic, rather than anabolic compound. However, a recent study has shown that HMB supplementation induces muscle hypertrophy in the extensor digitorum longus and soleus muscles in rats via mammalian target of rapamycin pathway [12], in addition to attenuating the depression in protein synthesis induced by the proteolysis-inducing factor [6]. In geldings fed an alfalfa-based supplement containing 10 g of HMB per day during 6 weeks of low to moderate-intensity training followed by 6 weeks of high-intensity training, HMB supplementation resulted in a 10% improvement in treadmill endurance [13]. This was followed by a study in racing Thoroughbreds where HMB-supplemented horses had reduced serum CK, maintained body weight better, needed less recovery time between races, and had a better win rate. These effects were most likely through a decrease in training and race-related muscle damage and increased aerobic ability, which allowed for a quicker recovery after racing.

GO is a mixture of ferulic acid esters of sterol and triterpene alcohols extracted from rice bran, and is known to be a powerful inhibitor of iron-driven hydroxyl radical formation; it has also been reported to possess antioxidant activity in stabilizing lipids [14]. Because GO is insoluble in water, a GO emulsion is used in supplementing humans, dogs, and horses. There are few studies in the peer-reviewed literature on GO, despite its apparent use as an ergogenic aid. One study looked at resistance-weight-trained male athletes supplemented with 500 mg/d GO or a placebo [15]. However, this study failed to show an effect of GO on training performance.

Thoroughbred horses undergo intensive training starting at a young age. The results of this training and their race performance may be improved by the use of dietary supplementation. The use of supplementation may not only improve performance but also improve muscle recovery after a race or heavy training period. Therefore, the main objective of this study was to evaluate the effect of dietary supplementation of HMB and GO on exercise parameters in horses trained from winter break to their maximal physical performance at the start of the racing season. Our hypothesis is that one or both supplements, either alone or in combination, will decrease muscle damage and improve recovery, and thus improve overall performance.

Section snippets

Horses

Twenty-four Thoroughbred racehorses ranging in age from 3-6 years (12 mares and 12 stallions) and weighing 520 ± 50 kg were studied at the Sluzewiec Racetrack training center (Warsaw, Poland). The horses were privately owned, and the experimental design and all procedures were approved by the Ethical Committee in Warsaw and by the owners of horses. The horses were selected on the basis of a clinical examination and hematological analysis, and horses with pathological conditions were excluded.

Exercise Monitoring

Resting and peak HR as well as maximum speed did not differ between placebo and experimental groups (Fig. 2). Resting HR during all exercise sessions was in the range of 32-37 beats/min. Average peak HR was approximately 200 beats/min for all exercised horses and was not affected by the length of training. Maximal speed increased from average 38 km/hr at the beginning of training to about 50 km/hr at the end of the racing season. These data confirm that training exertion was similar and intense

Discussion

The present study was the first study to determine whether dietary supplementation with either HMB or GO alone, or in combination, would affect indirect markers of muscle damage and fatigue in Thoroughbred horses during 16 weeks of training in preparation for the racing season. Currently, little data are available on the effects of these supplements in horses, with only one study describing the effect of HMB on the physiological response to exercise in horses. Miller et al. [13] fed horses an

Conclusion

This field study, performed on 22 trained Thoroughbred horses, is the first showing that dietary supplementation with GO and HMB may significantly improve training results by decreasing muscle damage caused as a result of the intensity of the training. The current study has shown that GO does not significantly affect performance-related physiological parameters in training Thoroughbred race horses; however, when GO is supplemented with HMB, the training results in increased performance

Acknowledgments

The study was supported by the State Committee for Scientific Research, Poland (grant number N N308 3076 33 for P.O.). The authors thank Mrs Małgorzata Podgurniak and Dr John C. Fuller for their assistance with the manuscript preparation.

References (36)

  • H.L. Eley et al.

    Signaling pathways initiated by β-hydroxy-β-methylbutyrate to attenuate the depression of protein synthesis in skeletal muscle in response to cachectic stimuli

    Am J Physiol Endocrinol Metab

    (2007)
  • S. Nissen et al.

    Effect of leucine metabolite β-hydroxy-β-methylbutyrate (HMB) on muscle metabolism during resistance exercise training

    J Appl Physiol

    (1996)
  • A.E. Knitter et al.

    Effects of β-hydroxy-β-methylbutyrate on muscle damage after a prolonged run

    J Apply Physiol

    (2000)
  • K. Van Someren et al.

    Supplementation with beta-hydroxy-beta-methylbutyrate (HMB) and alpha-ketoisocaproic acid (KIC) reduces signs and symptoms of exercise-induced muscle damage in man

    Int J Sport Nutr

    (2005)
  • H.J. Smith et al.

    Attenuation of proteasome-induced proteolysis in skeletal muscle by β-hydroxy-β-methylbutyrate in cancer induced muscle loss

    Cancer Res

    (2005)
  • G.D. Pimentel et al.

    β-hydroxy-β-methylbutyrate supplementation stimulates skeletal muscle hypertrophy in rats via the mTOR pathway

    Nutr Metabol

    (2011)
  • P. Miller et al.

    The effect of supplemental β-hydroxy-β-methylbutyrate on training and racing thoroughbreds

    Proc 17th Assoc Equine Sport Med

    (1998)
  • J.S. Kim et al.

    Restructured beef roasts containing rice bran oil and fiber influences cholesterol oxidation and nutritional profile

    J Muscle Foods

    (2000)
  • Cited by (0)

    View full text