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Equine veterinary journal. Supplement2007; (36); 335-339; doi: 10.1111/j.2042-3306.2006.tb05564.x

Synthesis of proglycogen and macroglycogen in skeletal muscle of standardbred trotters after intermittent exercise.

Abstract: The degradation of glycogen and its two forms, proglycogen (PG) and macroglycogen (MG) has been studied in horses performing different types of exercise, but no information is available about the resynthesis of PG and MG after exercise. Objective: To determine the resynthesis of PG and MG in skeletal muscle after intermittent uphill exercise. Methods: At a training camp 9 well-trained Standardbred trotters performed a training session comprising a warm-up period, 7 repeated 500 m bouts of exercise on an uphill slope and a recovery period. Muscle biopsies (m. gluteus medius) for analysis of PG, MG, glucose and glucose-6-phosphate were taken at rest, at the end of exercise and 1, 4, 8, 24, 48 and 72 h post exercise. Blood samples for analysis of glucose, lactate and insulin were collected before exercise, immediately after the last bout of exercise and then as for the muscle biopsies. Results: The MG and PG concentration pre-exercise was 311 - 47 and 305 +/- 55 mmol/kg dwt respectively. The exercise caused a decrease in PG (A 63 +/- 26 mmol/kg dwt) and MG (delta 136 +/- 68 mmol/kg dwt). Immediately after the last sprint plasma glucose and lactate increased compared to values pre-exercise. During the first hour post exercise there was a further decrease in MG in 7 out of 9 horses. The rate of glycogen resynthesis during 1-24 h was higher for MG than for PG. The rate of muscle glycogen resynthesis thereafter was slower and did not differ between MG and PG up to 72 h. Conclusions: After repeated bouts of exercise on a slope, resynthesis of glycogen is a slow process and the resynthesis of proglycogen differs from that of macroglycogen. The fraction most depleted during exercise (MG) had no resynthesis during the first hour of recovery but then had the highest rate of resynthesis during the remainder of the first 24 h period. Conclusions: If the time between exercise sessions during training is too short the recovery period will be inadequate for complete restoration of muscle glycogen.
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Publication Date: 2007-04-04 PubMed ID: 17402443DOI: 10.1111/j.2042-3306.2006.tb05564.xGoogle Scholar: Lookup
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  • Non-U.S. Gov't

Summary

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This research investigated the process of glycogen synthesis in trained horses following intermittent uphill exercise, particularly focusing on the resynthesis of two forms of glycogen, proglycogen (PG) and macroglycogen (MG). It found that the reformation of glycogen takes time post exercise, with different recovery rates for the two forms of glycogen, ultimately concluding that short intervals between training sessions may not provide enough time for complete glycogen recovery.

Objective and Methodology of the Study

  • The study aimed to explore how PG and MG get synthesized in the skeletal muscles of horses following intermittent uphill exertion. There isn’t existing information on this subject, which adds to the novelty of this research.
  • The study involved an intensive training session comprising warm-up, repeated bouts of uphill exercise, and recovery periods.
  • Muscle biopsies of the gluteus medius muscle for analyzing PG, MG, glucose, and glucose-6-phosphate states took place during various intervals of exercise and during the resting periods after the exercise.
  • Blood samples were also collected before, right after the exercise, and throughout the recovery to analyze the glucose, lactate, and insulin levels.

Results

  • The research found that both PG and MG concentrations decrease during the exercise.
  • Plasma glucose and lactate levels rose immediately after the workout.
  • During the first hour of recovery, seven out of nine horses showed an additional decrease in MG levels.
  • The rate of glycogen resynthesis was higher for MG than PG in the first 24 hours after exercise. However, this rate slowed down thereafter and did not differ between MG and PG for 72 hours.

Conclusion

  • The research concluded that after vigorous uphill workout periods, the formation of glycogen is a slow process, and the synthesis of proglycogen varies from that of macroglycogen, with MG showing no resynthesis during the initial hour of recovery yet having the highest resynthesis rate overall in the first 24 hours.
  • It also highlighted that if the intervals between exercise sessions are too short, the recovery of muscle glycogen will not be complete, suggesting the need for sufficient time between training sessions.

Cite This Article

APA
Bröjer J, Holm S, Jonasson R, Hedenström U, Essén-Gustavsson B. (2007). Synthesis of proglycogen and macroglycogen in skeletal muscle of standardbred trotters after intermittent exercise. Equine Vet J Suppl(36), 335-339. https://doi.org/10.1111/j.2042-3306.2006.tb05564.x

Publication

Equine veterinary journal. Supplement
NlmUniqueID: 9614088
Country: United States
Language: English
Issue: 36
Pages: 335-339

Researcher Affiliations

Bröjer, J
  • Department of Clinical Sciences, Swedish University of Agricultural Sciences, SE-750 07 Uppsala, Sweden.
Holm, S
    Jonasson, R
      Hedenström, U
        Essén-Gustavsson, B

          MeSH Terms

          • Analysis of Variance
          • Animals
          • Biopsy / veterinary
          • Exercise Test / veterinary
          • Female
          • Glucose / metabolism
          • Glucose-6-Phosphate / metabolism
          • Glycogen / biosynthesis
          • Heart Rate / physiology
          • Horses / metabolism
          • Horses / physiology
          • Male
          • Muscle, Skeletal / metabolism
          • Physical Conditioning, Animal / physiology
          • Time Factors

          Citations

          This article has been cited 4 times.
          1. Johnson SE, Barshick MR, Gonzalez ML, Riley JW, Pelletier ME, Castanho BC, Ealy EN. A Carnitine-Containing Product Improves Aspects of Post-Exercise Recovery in Adult Horses. Animals (Basel) 2023 Feb 14;13(4).
            doi: 10.3390/ani13040657pubmed: 36830444google scholar: lookup
          2. Jang HJ, Kim DM, Kim KB, Park JW, Choi JY, Oh JH, Song KD, Kim S, Cho BW. Analysis of metabolomic patterns in thoroughbreds before and after exercise. Asian-Australas J Anim Sci 2017 Nov;30(11):1633-1642.
            doi: 10.5713/ajas.17.0167pubmed: 28728374google scholar: lookup
          3. Mojibi N, Rasouli M. Comparison of Methods to Assay Liver Glycogen Fractions: The Effects of Starvation. J Clin Diagn Res 2017 Mar;11(3):BC17-BC20.
            doi: 10.7860/JCDR/2017/24783.9555pubmed: 28511372google scholar: lookup
          4. Nostell KE, Essén-Gustavsson B, Bröjer JT. Repeated post-exercise administration with a mixture of leucine and glucose alters the plasma amino acid profile in Standardbred trotters. Acta Vet Scand 2012 Feb 1;54(1):7.
            doi: 10.1186/1751-0147-54-7pubmed: 22296999google scholar: lookup
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