Today, somewhat delayed because of rain, was the eat & walk experiment.
Background: Muscles “store energy” in the form of glycogen, as stated by respected websites on the topic. Glycogen still needs oxygen to release energy, but nothing more. The pulse therefore remains fairly low during moderate exercise. Once glycogen reserves fall below a threshold level, muscles request nourishment from elsewhere in the body, and the pulse increases. If the glycogen is further depleted, an emergency recharging takes place after exercise, and the pulse remains elevated until glycogen reaches an acceptable (for the muscles) level.
After a carbohydrate-rich meal, blood sugar rises. Body releases insulin, which orders muscles (and liver) to absorb sugar and convert it into glycogen. Â This continues until blood sugar reaches normal level or glycogen storage is full.
Hypothesis: By walking briskly after eating, the insulin should flood the leg muscles with glucose, which they can burn instead of depleting glycogen during exercise and replace it later. The body should secrete less insulin and there should be no spike in blood sugar.
Observation: My pulse increased early to above 120, against normal 110 at this phase. This is to be expected, since the heart would have to supply plenty of blood to digestive tract, liver and muscles all at once.
I walked for one hour and 25 minutes, ten minutes longer than normal for the last couple weeks. The pulse was still in the 125 range at the end of the trip. Energy use was calculated by my pulse watch to 900 calories. This is in a similar range as the meal eaten.
Pulse after exercise was slightly higher than after inactivity. This could be a sign of moderate recharging of muscles, or of delayed digestion. Inconclusive.
Sleepiness and lethargy that is often experienced after a meal was not present during the walk.
Subjective experience of stiffness and tiredness in leg muscles was consistent with a 900 calorie activity. It would seem that the stiffness of muscles after activity is NOT caused by depletion of glycogen reserves. Cause still unknown. The effect seems incompatible with intelligent design if we assume unlimited access to food. Otherwise, incentives to restrict unaccustomed activity in adults may have been useful in the past.
Conclusion: The experiment was slightly unpleasant and did not bring a clear conclusion as to whether light exercise causes less blood sugar spike / insulin production, although the lack of drowsiness may imply this.