Physiological and skeletal muscle responses to high-intensity interval exercise in Thoroughbred horses

IntroductionThe purpose of this study was to determine whether acute high-intensity interval exercise or sprint interval exercise induces greater physiological and skeletal muscle responses compared to moderate-intensity continuous exercise in horses.MethodsIn a randomized crossover design, eight tr...

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Main Authors: Kazutaka Mukai, Hajime Ohmura, Yuji Takahashi, Yusaku Ebisuda, Koki Yoneda, Hirofumi Miyata
Format: Article
Language:English
Published: Frontiers Media S.A. 2023-11-01
Series:Frontiers in Veterinary Science
Subjects:
Online Access:https://www.frontiersin.org/articles/10.3389/fvets.2023.1241266/full
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author Kazutaka Mukai
Hajime Ohmura
Yuji Takahashi
Yusaku Ebisuda
Koki Yoneda
Hirofumi Miyata
author_facet Kazutaka Mukai
Hajime Ohmura
Yuji Takahashi
Yusaku Ebisuda
Koki Yoneda
Hirofumi Miyata
author_sort Kazutaka Mukai
collection DOAJ
description IntroductionThe purpose of this study was to determine whether acute high-intensity interval exercise or sprint interval exercise induces greater physiological and skeletal muscle responses compared to moderate-intensity continuous exercise in horses.MethodsIn a randomized crossover design, eight trained Thoroughbred horses performed three treadmill exercise protocols consisting of moderate-intensity continuous exercise (6 min at 70% VO2max; MICT), high-intensity interval exercise (6 × 30 s at 100% VO2max; HIIT), and sprint interval exercise (6 × 15 s at 120% VO2max; SIT). Arterial blood samples were collected to measure blood gas variables and plasma lactate concentration. Biopsy samples were obtained from the gluteus medius muscle before, immediately after, 4 h, and 24 h after exercise for biochemical analysis, western blotting and real-time RT-PCR. Effects of time and exercise protocol were analyzed using mixed models (p < 0.05).ResultsHeart rate and plasma lactate concentration at the end of exercise were higher in HIIT and SIT than those in MICT (heart rate, HIIT vs. MICT, p = 0.0005; SIT vs. MICT, p = 0.0015; lactate, HIIT vs. MICT, p = 0.0014; SIT vs. MICT, p = 0.0003). Arterial O2 saturation and arterial pH in HIIT and SIT were lower compared with MICT (SaO2, HIIT vs. MICT, p = 0.0035; SIT vs. MICT, p = 0.0265; pH, HIIT vs. MICT, p = 0.0011; SIT vs. MICT, p = 0.0023). Muscle glycogen content decreased significantly in HIIT (p = 0.0004) and SIT (p = 0.0016) immediately after exercise, but not in MICT (p = 0.19). Phosphorylation of AMP-activated protein kinase (AMPK) in HIIT showed a significant increase immediately after exercise (p = 0.014), but the increase was not significant in MICT (p = 0.13) and SIT (p = 0.39). At 4 h after exercise, peroxisome proliferator-activated receptor γ co-activator-1α mRNA increased in HIIT (p = 0.0027) and SIT (p = 0.0019) and vascular endothelial growth factor mRNA increased in SIT (p = 0.0002).DiscussionDespite an equal run distance, HIIT and SIT cause more severe arterial hypoxemia and lactic acidosis compared with MICT. In addition, HIIT activates the AMPK signaling cascade, and HIIT and SIT elevate mitochondrial biogenesis and angiogenesis, whereas MICT did not induce any significant changes to these signaling pathways.
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spelling doaj.art-7f76845329ea487ca71f1920c464cb002023-11-14T03:13:05ZengFrontiers Media S.A.Frontiers in Veterinary Science2297-17692023-11-011010.3389/fvets.2023.12412661241266Physiological and skeletal muscle responses to high-intensity interval exercise in Thoroughbred horsesKazutaka Mukai0Hajime Ohmura1Yuji Takahashi2Yusaku Ebisuda3Koki Yoneda4Hirofumi Miyata5Sports Science Division, Equine Research Institute, Japan Racing Association, Shimotsuke, JapanSports Science Division, Equine Research Institute, Japan Racing Association, Shimotsuke, JapanSports Science Division, Equine Research Institute, Japan Racing Association, Shimotsuke, JapanSports Science Division, Equine Research Institute, Japan Racing Association, Shimotsuke, JapanBiological Sciences, Graduate School of Sciences and Technology for Innovation, Yamaguchi University, Yamaguchi, JapanBiological Sciences, Graduate School of Sciences and Technology for Innovation, Yamaguchi University, Yamaguchi, JapanIntroductionThe purpose of this study was to determine whether acute high-intensity interval exercise or sprint interval exercise induces greater physiological and skeletal muscle responses compared to moderate-intensity continuous exercise in horses.MethodsIn a randomized crossover design, eight trained Thoroughbred horses performed three treadmill exercise protocols consisting of moderate-intensity continuous exercise (6 min at 70% VO2max; MICT), high-intensity interval exercise (6 × 30 s at 100% VO2max; HIIT), and sprint interval exercise (6 × 15 s at 120% VO2max; SIT). Arterial blood samples were collected to measure blood gas variables and plasma lactate concentration. Biopsy samples were obtained from the gluteus medius muscle before, immediately after, 4 h, and 24 h after exercise for biochemical analysis, western blotting and real-time RT-PCR. Effects of time and exercise protocol were analyzed using mixed models (p < 0.05).ResultsHeart rate and plasma lactate concentration at the end of exercise were higher in HIIT and SIT than those in MICT (heart rate, HIIT vs. MICT, p = 0.0005; SIT vs. MICT, p = 0.0015; lactate, HIIT vs. MICT, p = 0.0014; SIT vs. MICT, p = 0.0003). Arterial O2 saturation and arterial pH in HIIT and SIT were lower compared with MICT (SaO2, HIIT vs. MICT, p = 0.0035; SIT vs. MICT, p = 0.0265; pH, HIIT vs. MICT, p = 0.0011; SIT vs. MICT, p = 0.0023). Muscle glycogen content decreased significantly in HIIT (p = 0.0004) and SIT (p = 0.0016) immediately after exercise, but not in MICT (p = 0.19). Phosphorylation of AMP-activated protein kinase (AMPK) in HIIT showed a significant increase immediately after exercise (p = 0.014), but the increase was not significant in MICT (p = 0.13) and SIT (p = 0.39). At 4 h after exercise, peroxisome proliferator-activated receptor γ co-activator-1α mRNA increased in HIIT (p = 0.0027) and SIT (p = 0.0019) and vascular endothelial growth factor mRNA increased in SIT (p = 0.0002).DiscussionDespite an equal run distance, HIIT and SIT cause more severe arterial hypoxemia and lactic acidosis compared with MICT. In addition, HIIT activates the AMPK signaling cascade, and HIIT and SIT elevate mitochondrial biogenesis and angiogenesis, whereas MICT did not induce any significant changes to these signaling pathways.https://www.frontiersin.org/articles/10.3389/fvets.2023.1241266/fullhigh-intensity interval trainingskeletal musclehorsemitochondrialactate
spellingShingle Kazutaka Mukai
Hajime Ohmura
Yuji Takahashi
Yusaku Ebisuda
Koki Yoneda
Hirofumi Miyata
Physiological and skeletal muscle responses to high-intensity interval exercise in Thoroughbred horses
Frontiers in Veterinary Science
high-intensity interval training
skeletal muscle
horse
mitochondria
lactate
title Physiological and skeletal muscle responses to high-intensity interval exercise in Thoroughbred horses
title_full Physiological and skeletal muscle responses to high-intensity interval exercise in Thoroughbred horses
title_fullStr Physiological and skeletal muscle responses to high-intensity interval exercise in Thoroughbred horses
title_full_unstemmed Physiological and skeletal muscle responses to high-intensity interval exercise in Thoroughbred horses
title_short Physiological and skeletal muscle responses to high-intensity interval exercise in Thoroughbred horses
title_sort physiological and skeletal muscle responses to high intensity interval exercise in thoroughbred horses
topic high-intensity interval training
skeletal muscle
horse
mitochondria
lactate
url https://www.frontiersin.org/articles/10.3389/fvets.2023.1241266/full
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