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Muscle metaboreflex activation by static exercise dilates pupil in humans
1Institute of Health Science, Kyushu University, Kasuga, Fukuoka 816-8580, Japan. naohayashi@ihs.kyushu-u.ac.jp
European Journal of Applied Physiology
|November 16, 2010
Summary
Static exercise, like handgrip, increases pupil diameter. This effect is partly caused by the muscle metaboreflex, a feedback loop involving metabolically sensitive nerves in muscles.
Area of Science:
- Physiology
- Autonomic Nervous System Research
- Exercise Physiology
Background:
- Sympathetic nervous system activity influences various physiological responses, including pupil diameter.
- The metaboreflex, activated by metabolically sensitive skeletal muscle afferents, plays a role in sympathetic regulation during exercise.
- Understanding the interplay between static exercise, metaboreflex, and autonomic control of pupil size is crucial.
Purpose of the Study:
- To investigate the hypothesis that static exercise and metaboreflex activation influence sympathetic nervous activity modulating pupil diameter.
- To determine the specific contribution of the metaboreflex to exercise-induced changes in pupil diameter.
Main Methods:
- Nine healthy subjects participated in the study.
- Isometric handgrip exercise at 30% maximal voluntary contraction was performed for 2 minutes.
- Postexercise muscle ischemia (PEMI) was applied to the forearm in one trial, while a control trial involved no PEMI.
Main Results:
- Both static handgrip exercise and PEMI significantly increased pupil diameter and mean blood pressure (MAP) compared to rest.
- The increases in pupil diameter and MAP were sustained during PEMI.
- These parameters returned to baseline levels during the recovery period in the control trial.
Conclusions:
- Static handgrip exercise leads to an increase in human pupil diameter.
- The activation of the muscle metaboreflex contributes to the exercise-induced increase in pupil diameter.
- These findings highlight the role of the metaboreflex in autonomic regulation during static exercise.
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