Exercise may ward off Alzheimer's and Parkinson's

When US scientists gave non-exercising mice a protein produced by exercising mice, they found it switched on genes that help preserve brain health and boost growth of new nerves in regions important for learning and memory.

They suggest their findings could pave the way to a drug that improves treatments against cognitive decline in older people and help slow progression of brain-wasting diseases like Alzheimer's and Parkinson's.

Dr. Bruce Spiegelman, from Dana-Farber Cancer Institute and Harvard Medical School in Boston reports the discovery in the latest online issue of the journal Cell Metabolism.

Endurance exercise has previously been shown to improve brain function, particularly in older people. But until this study the underlying molecular mechanisms were not understood.

In an earlier study, Dr. Spiegelman's team had already discovered that the protein, called FNDC5, is released into the bloodstream as a variant called irisin as a result of muscular exertion.

In this latest work, the researchers monitored the effect of endurance exercise on mice (they voluntarily ran on an exercise wheel for 30 days).

Boosting production of FNDC5

They found endurance exercise increased the effect of a regulatory metabolic compound, PGC-1alpha in the muscles of mice, which boosted production of FNDC5. This had the knock-on effect of switching on genes that increased the expression of a brain-protective protein, BDNF, in the hippocampus, a part of the brain involved in learning and memory.

Researchers found that a protein produced during exercise switches on genes that preserve brain health.

The hippocampus is only one of two areas in the adult brain that can grow new nerve cells. Exercise increases the effect of BDNF in the hippocampus, where it preserves brain cells and promotes the growth of new nerves and synapses or junctions between nerve cells, thereby aiding learning and memory.

But until now it was not clear what linked exercise to BDNF at the molecular level, which is what you need to know in order to develop drugs that have the same effect.

This study is the first to suggest that the molecular pathway that links exercise to raised BDNF activity goes via PGC-1alpha and FNDC5.

However, the authors suggest there may also be other pathways, waiting to be discovered.

In a second stage of the study, the researchers showed artificially increasing FNDC5 without the help of exercise had the same effect.

Dr. Spiegelman says:

"What is exciting is that a natural substance can be given in the bloodstream that can mimic some of the effects of endurance exercise on the brain."

However, he cautions that more studies are now needed to find out whether giving mice FNDC5 actually leads to improved brain function.

Also, the researchers did not establish whether it was FNDC5 itself that ended up in the brains of the mice, or its variant, irisin.

If drug developers choose to start with irisin, they will first have to make a more stable form of the protein, says Dr. Spiegelman.

Funds from the JPB Foundation and National Institutes of Health helped finance the study.

Earlier this year, researchers from Princeton University reported in the Journal of Neuroscience that physicalexercise helps the brain withstand stress.

Written by Catharine Paddock PhD

Exercise Helps Brain Become More Resilient To Stress

Physical exercise reorganizes the human brain so that it responds better to stress and normal brain function is less likely to be affected by anxiety, researchers from Princeton University wrote in the Journal of Neuroscience.

In an animal experiment, the authors found that when very physically active mice were exposed to a stressor - cold water - neurons in their brains that shut off excitement in the ventral hippocampus became much more active. The ventral hippocampus is a region in the brain that regulates anxiety.

This study may also resolve an inconsistency in research regarding the effect exercise has on the brain - namely that physical activity lowers anxiety while at the same time encouraging the growth of new neurons in the ventral hippocampus.

Exercise should, in theory, lead to more anxiety, not less, because these young neurons are typically more excitable than their older equivalents. However, this study found that physical activity also enhances the mechanisms that stop these neurons from firing.

Senior author, Elizabeth Gould, Princeton's Dorman T. Warren Professor of Psychology, explained that the effect physical exercise might have on the ventral hippocampus specifically has not been explored deeply. In this study, the team was able to isolate brain cells and regions that play key roles in the regulation of anxiety. They believe their findings may help researchers better understand and treat anxiety disorders.

From an evolutionary perspective, the study also showed how the brain can be surprisingly adaptive, tailoring its own processes to an organism's surroundings and lifestyle. Less physically fit creatures, for example, may benefit from a higher likelihood of anxious behavior. Gould said "Anxiety often manifests itself in avoidant behavior and avoiding potentially dangerous situations would increase the likelihood of survival, particularly for those less capable of responding with a 'fight or flight' reaction."

Professor Gould said:

"Understanding how the brain regulates anxious behavior gives us potential clues about helping people with anxiety disorders. It also tells us something about how the brain modifies itself to respond optimally to its own environment."

In this study, the mice were divided into two groups:

• The active group - all the mice had free access to a running wheel
• The sedentary group - there was no running wheel

Mice love running - give them a wheel and they will run about 2.5 miles (4 kilometers) every night. Six weeks later, the mice were exposed to brief periods of cold water.

Nearly as soon as they were exposed to the cold water (the stressor) the brains of the sedentary and active mice behaved differently:

• In the sedentary group, the cold water triggered an increase in "immediate early genes" - short-lived genes that are turned on rapidly when a neuron fires.
• In the active group these genes were not present, suggesting that their neurons did not immediately become super excited in response to the stressor.

The brain of an active mouse "showed every sign of controlling its reaction to an extent not observed in the brain of a sedentary mouse". Inhibitory neurons, which are known to keep excitable neurons in check, became much more active. Also, the neurons in the active mice's brains released more GABA (gamma-aminobutyric acid), a neurotransmitter that calms down neural excitement. There were higher levels of the protein that packages GABA into vesicles for release into the synapse in the active mice.

When the scientists blocked the GABA receptor that tamps down neural activity in the ventral hippocampus, the anxiety-reducing effect of physical exercise was canceled out.

In an Abstract in the journal, the researchers concluded:

"Together, these results suggest that running improves anxiety regulation by engaging local inhibitory mechanisms in the ventral hippocampus."

Exercise, even when forced, reduces anxiety and depressive symptoms

Even forced exercise reduces anxiety - physical activity helps relieve the symptoms of anxiety and depression whether you exercised because you wanted to or were forced to, researchers from the University of Colorado, Boulder, wrote in the European Journal of Neurosciences (February 2013 issue).

The authors explained that previous studies had demonstrated how exercise can help protect against stress-related disorders. However, nobody had looked into the effect forced exercise might have on anxiety. Examples of forced exercise may be seen among high school students, college and professional sportsmen and women, and military personnel.

Greenwood wondered "If exercise is forced, will it still produce mental health benefits? It's obvious that forced exercise will still produce peripheral physiological benefits. But will it produce benefits to anxiety and depression?"

The researchers designed an animal experiment using rats. They were divided into two groups, active and sedentary. The active group was further split into two, with one running whenever it wanted, and the other having to run on mechanized wheels that turned on at different speeds and for varying periods so that both active groups ended up doing the same amount of exercise.

Six weeks later the rats were exposed to a stressor and their anxiety levels were tested the following day.

They found that regardless of whether the rats were forced to run or chose to, the physically active rats were protected against stress and anxiety equally, compared to the sedentary rats.

Greenwood said "The implications are that humans who perceive exercise as being forced - perhaps including those who feel like they have to exercise for health reasons - are maybe still going to get the benefits in terms of reducing anxiety and depression.

A British study showed that regular intense physical exercise protects men from anxiety and depression for many years after they stop.

Written by Christian Nordqvist

Bodyweight exercise

Bodyweight exercises are strength training exercises that do not require free weights; the practitioner's own weight provides the resistance for the movement. Movements such as the push-up, the pull-up, and the sit-up are some of the most common bodyweight exercises.

In general, increasing the amount of repetitions will focus on improving endurance, while strength gains are made through increasing the intensity of the exercise through decreasing leverage and working at the ends of range of motion.^[1]

Contents

  [hide] 

• 1 Advantages
• 2 Disadvantages
• 3 List of exercises
• 4 See also
• 5 References

Advantages[edit]

Because they do not require weights, bodyweight exercises are the ideal choice for individuals who are interested in fitness but do not have access to equipment. However that doesn't mean strength can't be gained when practicing it. Weights can be incorporated to increase the difficulty of most bodyweight exercises and some exercises do require some sort of apparatus to lean on or hang from, but the majority of bodyweight exercises require only a floor. For those exercises that do require equipment of some kind, a substitute can usually be improvised, for example using two branches of a tree to perform triceps dips. Some bodyweight exercises have been shown to benefit not just the young, but the elderly also.^[2]

Bodyweight exercises, compared to weight lifting, often require much more flexibility and balance in order to perform repetitions. Such exercises include handstand pushups, planche pushups, and bridges. Many bodyweight exercises can be progressed or regressed to meet the individual's need. This progression/regression strategy allows nearly all levels of fitness to participate. Bodyweight training can be used effectively to strengthen the core muscles with the addition of speed or unstable surfaces (such as a stability ball) as well as exercise variations that limit the motion (such as extra wide push-ups or wide pull-ups).

Disadvantages[edit]

Bodyweight exercises use the practitioner's own weight to provide the resistance for the movement. This means that the weight being lifted is never greater than the weight of one's own body. This can make it difficult to achieve a level of intensity that is near their one rep maximum, which is desirable for strength training. Bodyweight exercises can beincreased in intensity by including additional weights (such as wearing a weighted vest or holding a barbell, kettlebell, sandbell or plate during a sit up) or by altering the exercise to put one's self at a leverage disadvantage (such as elevating the feet, hanging from straps to change leverage, using one limb, and incorporating isometrics).

Gymnasts make extensive use of this last technique by doing much of their training with straight arms (such as iron crosses, levers, and planches), giving them a mechanically disadvantaged position.^[1] Furthermore, a unilateral progression scheme can be used. Instead of a bilateral movement, such as a two-handed pull-up, the practitioner may decide, for strength increases, to choose a set of exercises that will allow him/herself to complete the one-arm pull up. In the bodyweight-training community, unilateral movements are highly regarded and sought after.

Bodyweight exercises can also be modified to decrease the intensity. For instance, a practitioner unable to perform a single push-up may perform them with the knees on the ground, or replace pull-ups with bodyweight rows (i.e. a pull-up but with a lower bar such that the body is at an angle with the heels on the ground).

List of exercises[edit]

This is a list of common bodyweight exercises. Most of these exercises have several variants that can be performed to make the exercise more or less challenging, or to train different muscles. These variants are described in the articles covering the individual exercises.

Name	Muscle groups	Description
Press-up / Push-up	Chest, triceps, shoulders	In a prone position, the body is raised and lowered using the arms while the back remains straight and the toes remain on the ground. The exercise can be made more difficult by placing the legs at an incline. Thus, the upper body must support more weight. The exercise can be made even more difficult by performing it with a single arm. Notable variations include the Hindu pushup (dand), the divebomber pushup, and the diamond pushup.
Handstand push-up	Shoulders, triceps, trapezius	The body is positioned in a handstand, is lowered and pushed up.
Planche	Full Body	Holding one's body in the air, in a line parallel to and facing the floor through balancing one's entire bodyweight on both hands with straight arms.
Dip	Arms (triceps), chest,back	Hanging from a dip bar or other implement with the arms straight and the shoulders positioned above the hands, the body is lowered until the arms are bent at a 90 degrees angle.
Plank	Core (abdominals, back and shoulders)	Lying on the stomach and lifting the body by keeping the toes and forearms on the ground.
Sit-up	Abdomen, hip flexors	It begins with lying with the back on the floor, typically with the knees bent in an attempt to reduce stress on the back muscles and spine, and then elevating both the upper and lower vertebrae from the floor until everything superior to the buttocks is not touching the ground.
Crunch	Abdomen	Lying face up on the floor, the shoulders are curled towards the pelvis while the lower back remains flat against the floor. Focus is put on contracting the abdominal muscles.
Russian twist	Abdomen (especially the Obliques)	Sitting on the floor with knees bent as in a sit-up, with the back kept straight and at a 45 degree angle to the floor, the straightened arms are held outstretched with the hands locked together. The arms are moved from one side of the body to another in a twisting motion.
Leg raises	Abdomen, hip flexors	Lie on the floor on your back. Keep the lower back in contact with the floor and place hands to sides or under lower back for support. Lift legs upward as far as possible. Lower down to starting position slowly and with control. Make sure the back stays flat on floor and that the abdominal muscles are tight. The exercise can be made significantly harder by performing the exercises from a hanging apparatus, such as a pull up bar, and lifting the legs upwards until parallel with the ground. The exercise can further be increased in difficulty by lifting the legs to the utmost vertical position (to the head), and keeping the legs fully straight.
L-sit	Obliques, arms (triceps)	The person will sit in an L position with the legs straight and parallel to the ground and the upper body perpendicular to the ground. The hands are placed beside the glutes. The hands then push the entire body upwards off the ground. The legs must remain off the ground and parallel to the ground. The exercise taxes the muscles through isometric tension. A more difficult version is the V-sit, where the legs are held higher than parallel.
Pull up	Upper back - rear deltoid,trapezius, erector spinaeand especially thelatissimus dorsi, also thebiceps, brachialis, andabdomen.	Hanging from a bar with arms extended and palms facing away from the exerciser, the body is pulled up until the elbows are bent and the head is higher than the hands. The closer the hands, the more the emphasis on the biceps and elbow flexors. A variation is the chin-up, where the palms face towards the face, emphasizing the biceps.
Muscle up	(Refer to Pull Up and Dip)	Beginning with an aggressive pull up to chest level, often referred to as a high pull up, the wrists are then rotated to a position vertically above the bar which in turn helps to swing the elbows above the bar. A dip-like motion is then used to push the body up until the bar is at waist height. The transition between the high pull up and the low dip is the most difficult part and emphasizes the trapezius.
Human flag	Abdomen, shoulders	The person will grab a vertical object such as a pole or tree trunk, with both hands palms pronated. The practitioner will lift the entire body using the abdominal muscles into a position parallel to the ground.
Bridge	Back (deep spinal muscles), flexibility, arms (triceps), upper legs	The person will begin in a sit up position with the hands positioned by the ears, palms down, fingers facing the legs. The person pushes up with the arms and the back muscles until the body resembles a lowercase 'n'. The spine must be convex and the limbs straight. The exercise can be made harder by entering the bridge from a standing position (bending the back backwards in a controlled manner into the bridge.)
Hyperextension	Lower back, erector spinae	Lying face down on the floor, the torso and arms are lifted at the same time.
Squat	Legs	Standing up, the legs are bent at the knees and hips, lowering the torso between the legs. The torso leans forward to maintain balance. (Usually called a bodyweight squat to distinguish it from the use of weights.) The single leg squat, or "pistol squat", can be used to make the exercise significantly harder as it requires one to have a great deal of balance, flexibility, and strength.
Calf raises	Calf muscle	Standing calf raises are executed with one or both feet on a raised surface with the heel lower than the toes. The exercise is performed by raising the heel as far as possible. The exercise can be made harder by performing the exercise on one leg.
Burpee	Legs, Abdomen,Shoulders	From a standing position, the person drops to a squat with hands on floor (count 1), thrusts legs back to assume pushup position (count 2), returns to squat (count 3), and returns to standing position (count 4). The military 8-count version adds a pushup after count 2, and a jumping jack after count 4.