In vivo muscle function vs speed. II. Muscle function trotting up an incline.
Abstract: Different locomotor tasks, such as moving up or down grades or changing speed, require that muscles adjust the amount of work they perform to raise or lower, accelerate or decelerate the animal's center of mass. During level trotting in the horse, the triceps had shortening strains of around 10.6% while the vastus shortened 8.1% during the stance phase. Because of the 250% increase in metabolic rate in horses trotting up a 10% incline which is, presumably, a result of the increased requirement for mechanical work, we hypothesized that muscle strain during trotting would be increased in both the triceps and the vastus over that observed when trotting on the level. Because times of contact are similar in level and incline trotting, we also hypothesized that strain rates of these muscles would be increased, accompanied by an increase in EMG activity. We examined the lateral head of the triceps and the vastus lateralis while trotting up a 10% incline (5.7 degrees) over a range of speeds. The triceps shortened by 18% compared with 10.6% shortening on the level, and the vastus shortened by 18.5% compared with 8.1% on the level. The increased shortening velocities that were observed in both muscles probably reduced the force that any given set of activated muscle fibers could produce. If this pattern held for other limb muscles that do work to elevate the horse's center of mass on an incline, then a greater volume of muscle would have to be recruited to generate an equivalent force for body support. This was reflected in significant increases in the EMG intensity (IEMG) of both muscles.
Publication Date: 2005-03-16 PubMed ID: 15767317DOI: 10.1242/jeb.01485Google Scholar: Lookup
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- Comparative Study
- Journal Article
- Research Support
- U.S. Gov't
- P.H.S.
Summary
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This research investigates how horse muscles need to adjust work performance when moving up an incline at different speeds, focusing on the triceps and vastus muscles. As horses trot up a 10% incline, the study reveals a significant increase in muscle shortening and Electromyography (EMG) activity observed in contrast to level trotting.
Understanding Muscle Function in Different Locomotor Tasks
- The research opens with the focus on how muscles adapt to changes in locomotor tasks, such as moving up or down inclined surfaces or adjusting speed. These tasks necessitate that muscles modify the amount of work they output to accommodate the horse’s center of mass.
- The study particularly observes the strains on the triceps and vastus muscles in the horse, noting that during level (flat surface) trotting, the triceps experience around 10.6% shortening strains while the vastus shortens by 8.1% during the stance phase (when the horse’s foot is in contact with the surface).
Examination of Muscle Strain at Incline
- The researchers hypothesized that the strain on these muscles would increase when the horse trots up an incline due to a higher requirement for mechanical work – a theory supported by the observed 250% increase in metabolic rate in horses trotting up a 10% incline.
- This incline, assumedly, necessitates more effort to move against gravity and maintain balance, hence requiring more work from the muscles.
- The research also hypothesized that the same time of contact on both level and incline surfaces means an increase in strain rates, accompanied by an increase in EMG activity.
- To provide evidence for their hypotheses, the researchers examined the vastus lateralis and lateral head of the triceps of horses trotting up a 10% incline (5.7 degrees) at different speeds.
Findings from the Study
- The results showed that while trotting up an incline, the triceps shorten by 18% and the vastus shortens by 18.5%, an increase compared to the 10.6% and 8.1% shortening recorded when trotting on a level surface.
- The higher shortening velocities observed in both muscles would likely decrease the force that a given set of activated muscle fibers could produce. Thus, to generate an equivalent force needed for body support on an incline, a greater volume of muscle would need to be recruited.
- Supporting a major hypothesis, the researchers found significance increases in the EMG intensity (IEMG) of both muscles, indicating a higher rate of muscle activity when trotting up an incline.
Cite This Article
APA
Wickler SJ, Hoyt DF, Biewener AA, Cogger EA, De La Paz KL.
(2005).
In vivo muscle function vs speed. II. Muscle function trotting up an incline.
J Exp Biol, 208(Pt 6), 1191-1200.
https://doi.org/10.1242/jeb.01485 Publication
Researcher Affiliations
- Equine Research Center, California State Polytechnic University, Pomona, CA 91768-4032, USA. sjwickler@csupomona.edu
MeSH Terms
- Analysis of Variance
- Animals
- Biomechanical Phenomena
- Electromyography
- Energy Metabolism / physiology
- Forelimb / physiology
- Hindlimb / physiology
- Horses / physiology
- Joints / physiology
- Locomotion / physiology
- Muscle Contraction / physiology
- Muscle, Skeletal / physiology
Grant Funding
- S06 GM53933 / NIGMS NIH HHS
Citations
This article has been cited 17 times.- Takahashi Y, Takahashi T, Mukai K, Ebisuda Y, Ohmura H. Effect of speed and leading or trailing limbs on surface muscle activities during canter in Thoroughbred horses. PLoS One 2023;18(5):e0286409.
- St George LB, Spoormakers TJP, Smit IH, Hobbs SJ, Clayton HM, Roy SH, van Weeren PR, Richards J, Serra Bragança FM. Adaptations in equine appendicular muscle activity and movement occur during induced fore- and hindlimb lameness: An electromyographic and kinematic evaluation. Front Vet Sci 2022;9:989522.
- Li G, Zhang R, Han D, Pang H, Yu G, Cao Q, Wang C, Kong L, Chengjin W, Dong W, Li T, Li J. Forelimb joints contribute to locomotor performance in reindeer (Rangifer tarandus) by maintaining stability and storing energy. PeerJ 2020;8:e10278.
- Biewener AA. Locomotion as an emergent property of muscle contractile dynamics. J Exp Biol 2016 Jan;219(Pt 2):285-94.
- Wilkinson H, Thavarajah N, Codd J. The metabolic cost of walking on an incline in the Peacock (Pavo cristatus). PeerJ 2015;3:e987.
- Takahashi T, Matsui A, Mukai K, Ohmura H, Hiraga A, Aida H. The Effects of Inclination (Up and Down) of the Treadmill on the Electromyogram Activities of the Forelimb and Hind limb Muscles at a Walk and a Trot in Thoroughbred Horses. J Equine Sci 2014;25(4):73-7.
- Fischer S, Nolte I, Schilling N. Adaptations in muscle activity to induced, short-term hindlimb lameness in trotting dogs. PLoS One 2013;8(11):e80987.
- Arnold AS, Lee DV, Biewener AA. Modulation of joint moments and work in the goat hindlimb with locomotor speed and surface grade. J Exp Biol 2013 Jun 15;216(Pt 12):2201-12.
- Lee SS, de Boef Miara M, Arnold AS, Biewener AA, Wakeling JM. Recruitment of faster motor units is associated with greater rates of fascicle strain and rapid changes in muscle force during locomotion. J Exp Biol 2013 Jan 15;216(Pt 2):198-207.
- Fujiwara S, Hutchinson JR. Elbow joint adductor moment arm as an indicator of forelimb posture in extinct quadrupedal tetrapods. Proc Biol Sci 2012 Jul 7;279(1738):2561-70.
- Hanna JB, Schmitt D. Locomotor energetics in primates: gait mechanics and their relationship to the energetics of vertical and horizontal locomotion. Am J Phys Anthropol 2011 May;145(1):43-54.
- Fujiwara S, Endo H, Hutchinson JR. Topsy-turvy locomotion: biomechanical specializations of the elbow in suspended quadrupeds reflect inverted gravitational constraints. J Anat 2011 Aug;219(2):176-91.
- McGuigan MP, Yoo E, Lee DV, Biewener AA. Dynamics of goat distal hind limb muscle-tendon function in response to locomotor grade. J Exp Biol 2009 Jul;212(Pt 13):2092-104.
- Higham TE, Nelson FE. The integration of lateral gastrocnemius muscle function and kinematics in running turkeys. Zoology (Jena) 2008;111(6):483-93.
- Biewener AA, Daley MA. Unsteady locomotion: integrating muscle function with whole body dynamics and neuromuscular control. J Exp Biol 2007 Sep;210(Pt 17):2949-60.
- Mossor AM, McKamy AJ, Young MW, Rochté AJ, Avey-Arroyo JA, Nyakatura JA, Granatosky MC, Butcher MT, Young JW. Three-Dimensional Limb Kinematics in Brown-Throated Three-Toed Sloths (Bradypus variegatus) During Suspensory Quadrupedal Locomotion. J Exp Zool A Ecol Integr Physiol 2025 Jun;343(5):564-577.
- Takahashi Y, Takahashi T, Mukai K, Ebisuda Y, Ohmura H. Changes in muscle activation with graded surfaces during canter in Thoroughbred horses on a treadmill. PLoS One 2024;19(6):e0305622.
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