ABSTRACT
Many amphibious fishes rely on terrestrial locomotion to accomplish essential daily tasks, but it is unknown whether terrestrial exercise improves the locomotor performance of fishes on land. Thus, we tested the hypothesis that terrestrial exercise improves locomotion in amphibious fishes out of water as a result of skeletal muscle remodeling. We compared the jumping performance of Kryptolebias marmoratus before and after an exercise training regimen, and assessed the muscle phenotype of control and exercise-trained fish. We found that exercise-trained fish jumped 41% farther and 48% more times before reaching exhaustion. Furthermore, exercise training resulted in the hypertrophy of red muscle fibers, and an increase in red muscle capillarity and aerobic capacity. Lactate accumulation after jumping indicates that white muscle is also important in powering terrestrial jumps. Overall, skeletal muscle in K. marmoratus is highly responsive to terrestrial exercise, and muscle plasticity may assist in the effective exploitation of terrestrial habitats by amphibious fishes.
FOOTNOTES
Competing interests
The authors declare no competing or financial interests.
Author contributions
Conceptualization: W.M., G.S.R., P.A.W.; Methodology: W.M., G.S.R., P.A.W.; Validation: W.M., G.S.R., P.A.W.; Formal analysis: W.M., G.S.R.; Investigation: W.M., G.S.R.; Data curation: W.M., G.S.R.; Writing - original draft: W.M., G.S.R., P.A.W.; Writing - review & editing: G.S.R., P.A.W.; Visualization: G.S.R., P.A.W.; Supervision: P.A.W.; Funding acquisition: G.S.R., P.A.W.
Funding
Funding was provided by a Natural Sciences and Engineering Research Council of Canada (NSERC) graduate scholarship to G.S.R. and an NSERC Discovery Grant to P.A.W.
- Received August 28, 2019.
- Accepted September 25, 2019.
- © 2019. Published by The Company of Biologists Ltd
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