I was happy to find that what I have personally experienced has been proven to be true: forced exercise is not as beneficial as voluntary. Sometimes science actually proves our intuitions correct – surprise!
Stroke rehabilitation with different exercise paradigms has been investigated, but which one is more effective in facilitating motor recovery and up-regulating brain neurotrophic factor (BDNF) after brain ischemia would be interesting to clinicians and patients.
- Voluntary exercise,
- forced exercise, and
- involuntary muscle movement caused by functional electrical stimulation (FES)
have been individually demonstrated effective as stroke rehabilitation intervention.
One hundred and seventeen Sprague-Dawley rats were randomly distributed into four groups:
- Control (Con),
- Voluntary exercise of wheel running (V-Ex),
- Forced exercise of treadmill running (F-Ex), and
- Involuntary exercise of FES (I-Ex) with implanted electrodes placed in two hind limb muscles on the affected side to mimic gait-like walking pattern during stimulation.
Ischemic stroke was induced in all rats. Twenty-four hours after reperfusion, rats were arranged to their intervention programs.
De Ryck’s behavioral test was conducted daily during the 7-day intervention as an evaluation tool of motor recovery. Serum corticosterone concentration and BDNF levels in the hippocampus, striatum, and cortex were measured after the rats were sacrificed.
V-Ex had significantly better motor recovery in the behavioral test. V-Ex also had significantly higher hippocampal BDNF concentration than F-Ex and Con.
F-Ex had significantly higher serum corticosterone level than other groups.
Corticosterone is a stress hormone, so this means the forced exercise causes stress.
Voluntary exercise is the most effective intervention in upregulating the hippocampal BDNF level, and facilitating motor recovery.
Rats that exercised voluntarily also showed less corticosterone stress response than other groups.
The results also suggested that the forced exercise group was the least preferred intervention with
- high stress,
- low brain BDNF levels and
- less motor recovery.
Involuntarily exercising rats undergo more physical and mental stress than voluntarily exercising rats; however, these findings still lack electrophysiological evidence.
Many studies have reported that theta rhythm appears when there is mental stress and that it is affected by emotional status.
Thus we hypothesized that the differences between voluntary and involuntary movement should also exist in the hippocampal theta rhythm
Using the wheel and treadmill exercise models as voluntary and involuntary exercise models, respectively, this study wirelessly recorded the hippocampal electroencephalogram, electrocardiogram, and three-dimensional accelerations of young male rats.
Treadmill and wheel exercise produced different theta patterns in the rats before and during running.
When the same movement-related parameters are considered, the treadmill running group showed more changes in their theta frequency (4–12 Hz), in their theta power between 9.5–12 Hz, and in their heart rate than the wheel running group.
A positive correlation between the changes in high-frequency (9.5–12 Hz) theta power and heart rate was identified.
Our results reveal various voluntary and involuntary changes in hippocampal theta rhythm as well as divergences in heart rate and high-frequency theta activity that may represent the effects of an additional emotional state or the sensory interaction during involuntary running by rats.
Furthermore, theta activity also represents various special cognitive functions and/or special learning-related functions; therefore, an increase in theta power may be related to higher cognitive functioning and special learning functions
Treadmill running and wheel running are the most commonly used exercise models when studying rodents.
Treadmill exercise with defined exercise parameters (intensity, duration, etc.) can be considered an involuntary exercise model.
Wheel exercise, in which the rats can run freely in their cages, can be considered a voluntary model.
Compared with treadmill running (involuntary exercise model), wheel running (voluntary exercise model) causes lower levels of stress. Involuntary exercise results in a higher concentration of serum corticosterone but also results in reduced spatial learning and aversive memory after long-term training compared with voluntary exercise.
Since treadmill exercise causes a wide range of neuronal responses that may be related to stress, previous studies have identified that these two exercise models result in different types of brain functioning
In this study, we compared voluntary and involuntary exercise, using the wheel and treadmill models.
We have established a free-moving rat model that can be used to study various cerebral mechanisms simultaneously during treadmill exercise and wheel running, even in a pipe
The rats can run freely without physical restraint; in this context, any limits to their movement could result in a discontinuity of motion
We hypothesize that voluntary and involuntary exercise cause different patterns of theta rhythm before and during running. The different sensory stimuli from different types of exercise may affect theta rhythm.
The aims of the present study are as follows:
- first, to determine whether voluntary and involuntary exercise cause different changes in theta rhythm, both before and during running;
- second, to compare the two running models when the rats have the same movement-related parameters (physical activity, speed, heart rate); and
- third, to explore the relationship during running between theta rhythm and heart rate and between theta rhythm and physical activity.
Our study has established a platform for comparing the effects of voluntary and involuntary running on theta rhythm, heart rate, and physical activity. We used the wheel and treadmill running models as systems that allow voluntary and involuntary movement, respectively.
When the chronological order of running was examined, both wheel and treadmill running group showed increases in theta rhythm, heart rate, and physical activity
the treadmill running group was found to undergo more changes in Frq and HT of the theta rhythm and heart rate compared with the wheel running group when they had the same running speed and when they had the same heart rate.
This study is the first study to compare the differences in hippocampal theta rhythm between voluntary and involuntary movement
It is well known that both mental and physiological stresses are able to change heart rate.
Compared with an animal undertaking voluntary movement, involuntary running animals suffer more stress, especially psychological stress.
During forced exercise the rat is unable to be in control of speed and duration of movement.
the wheel running group showed fewer changes in heart rate across all situations than the treadmill running group. These results suggest that there exist factors other than physiological stress that are causing the increment in heart rate.
…that’s because heart rate responds to stress of involntary activity, while only the activity itself increases heart rate in voluntary exercise.
Compared with treadmill running rats, the wheel running rats ran in the same place, but the view was more extensive. Thus the sensory information is more complicated during wheel running than during treadmill running.
Voluntary and involuntary running show distinct theta patterns before and during running.
Involuntary running causes increases in theta frequency, high-frequency theta activity, and heart rate compared with voluntary running.
These discrepancies in high-frequency theta activity and heart rate between two exercise groups may represent the emotional status or the sensory interaction that occurs during running by the rat.
When exercise is forced by necessity or fear, like the fear of worsening pain if I don’t exercise, it becomes a painful, difficult, miserable chore. I get no pleasure from it or even after it (except that it is finally over) and the immediate pain from the activity feels overwhelming.
Only when I exercise because I’m feeling pretty good already, like when the worst of my pain is under control by opioids, do I feel any pleasure from it. Even when my joints pinch and muscles burn a bit, I feel like I’m really accomplishing something.
And here’s another study pointing out the same issue:
We investigated the effects of voluntary and involuntary exercise on the
- prefrontal cortex and hippocampus,
- vascular endothelial growth factor (VEGF),
- brain-derived neurotrophic factor (BDNF) levels, and
- spatial learning,
- memory and
in adolescent male and female rats.
The voluntary exercise group was given free access to a running wheel for 6 weeks. The involuntary exercise group was forced to run on a treadmill for 30 min at 8 m/min 5 days/week for 6 weeks.
Improved learning was demonstrated in both exercise groups compared to controls.
Neuron density in the CA1 region of the hippocampus, dentate gyrus and prefrontal cortex were increased. Hippocampal VEGF and BDNF levels were increased in both exercise groups compared to controls.
In females, anxiety and corticosterone levels were decreased;
This surprises me because when I’m stuck in it, my anxiety never eases no matter how much I exercise.
BDNF and VEGF levels were higher in the voluntary exercise group than in the involuntary exercise group.
The adolescent hippocampus is affected favorably by regular exercise.
And here’s a real surprise: males and females are affected differently by forced exercise.
- Although no difference was found in anxiety levels as a result of involuntary exercise in males,
- females showed increased anxiety levels, and decreased VEGF and BDNF levels in the prefrontal cortex after involuntary exercise.
Decreased BDNF means that the exercise was not as beneficial.
There are more and more reasons not to assume that research ignoring gender differences applies to both. All the studies on medications ignore the gender of the subjects and just lump them all together.
And the gender differences are just one of the significant differences between individuals that aren’t accounted for in research: there are different body types and personalities that have different reactions to different treatments.
The effects of opioids on different individuals depend on what’s going on with that person. If they have a predisposition to developing an addiction, they may get in trouble, but other people who have no such tendencies can use opioids responsibly and safely.
Why are responsible users of opioids punished for the acts of other people?
What does a patient with a desperate need for relief from overpowering pain have in common with someone injecting street drugs?
There is very, very little overlap between these two distinct groups.