The Effect of Acute and Chronic Exercise on Stress, Anxiety, and Depression

March 8, 2015

Abstract
Mental health is a severe problem in our society today, approximately 61.5 million of the Americans experience mental illness in each given year (NAMI, 2013). The main goal of this paper is to provide answers on how physical activity can replace anti-anxiety and depression drugs. To solve this question numerous research articles were examined by looking at how both acute and chronic bouts of aerobic and anaerobic exercise correlated with mental health aspects such as stress, depression, and anxiety. The findings showed that almost all types of exercise showed the capability of being able to improve mental health significantly. Thus, it is possible for physical activity to become a replacement for drugs being administered to the general population today, which allows people to treat their mental illness without the adverse side effects, which accompany drugs. This is supported by multiple studies done that compared physical exercise and drugs as treatments for mental disorders. All the studies support the claim that physical activity could be used as a replacement for drugs in treating mental illness. Introduction
Mental health illness is a severe issue affecting a significant portion of Americans every day. Serious mental illnesses have been reported to cost America $193.2 Billion in lost earning per year (NAMI, 2013). Specifically, 14.8 million people are reported to live with major depression while 42 million people reportedly live with anxiety disorders (NAMI, 2013). With this high portion of people having a mental illness, it means a lot of them are also taking drugs to help them cope and treat their specific disorders. These drugs have been shown to be associated with a multitude of negative side effects, which can be very hazardous to one’s health. This can result in severe and sometimes even fatal consequences for all ages (Lindsey, 2009).The purpose of this paper is to see if physical activity could be used as a replacement for these drugs, and how different forms and durations of physical activity could specifically affect mental disorders such as stress, anxiety and depression.
High levels of physical activity and cardiorespiratory fitness have been seen to be positively associated with mood enhancement and decreased levels of clinical depression in patients (Weir, 2011). Physical activity has also been observed to cause improved cognitive functioning, reduce the symptoms of anxiety, and overall lead to the improved mental health of a person. Those that engage in physical fitness about 2-3 times a week has shown to decrease their levels of depression, anger and stress compared to those who do not participate in physical activity (Stanescu & Vasile, 2014). Overall, these studies provide evidence for the beneficial relationship that exists between mental health and physical activity. Later on, it will be examined how different types and durations of physical activity will have an impact on mental disorders.
The two different durations of exercise are classified as acute and chronic. Chronic exercise is conducted over an extended period such as an eight-week treadmill-running regime while acute exercise would be classified as a single session of running on the treadmill until exhaustion (Liu, et al., 2000). An example of aerobic exercise would be jogging long distances while anaerobic exercise would be sprinting short distances or lifting weights (Liu, et al., 2000). These are the two types of exercises that will be examined and specifically it will be looked at how aerobic and anaerobic exercises performed at these two different durations will have an impact on the various aspects mental health. Aerobic and anaerobic bouts of exercise will be differentiated and explained.
Aerobic exercise requires energy and uses glycogen and fat as fuel, which allows low to moderate level of exertion to be able to be sustained over long periods of time (Gibson, 2012). Anaerobic exercise is exercise when oxygen is not present, and it uses glycogen as fuel (Gibson, 2012). Also in Anaerobic exercise, the body builds up lactic acid, which causes discomfort and ultimately fatigues if it is sustained for extended durations of time, which is why anaerobic exercise usually occurs in short bursts (Gibson, 2012). The different aspects of mental health that will be examined in this paper are introduced below.
Mental Health: Stress, Anxiety, and Depression
In the past, people with mental disorders were defined by diagnosis alone, and few classes of mental illness existed.This meant that people with mental illnesses were commonly stigmatized and institutionalized (Manderscheid, et al., 2010). This lead to scores of individuals with severe mental illnesses being released from state mental hospitals even though they were not cured, and it also leads to an increase in the population of the mentally ill people who were also homeless (Manderscheid, et al., 2010). As a result, a new definition of mental illness was formed to identify people with mental illnesses, and led to additional concepts of disability and duration being added to the definition, making it what it is today ( (Manderscheid, et al., 2010). Today mental illness has multiple different forms, and different treatments for each, and this is a result of the change in implementation on the national approach to mental illnesses. Since this paper is focusing stress, anxiety, and depression, each will be examined more thoroughly in the following section.
Stress
Stress is defined as to subject, stress, strain, and to overwork or fatigue a person (Butler, 1993).Thus, it can be caused by many of the daily activities people go through such as school and work. Stress has also been shown to lead to other mental disorders; specifically, chronic adolescent stress has been demonstrated to cause depressive-like behavior (Wulsin, Wick-Carlson, Packard, R.Morano, & Herman, 2016). Stressful experiences during early life have also been shown to affect brain development, which results in the exertion of profound and lasting influence on both mental development and psychological health (Hsiao, et al., 2016). Stress itself can cause many problems in people, and with its ability to cause other mental disorders to develop, makes it a severe mental disorder in society today. There are three different types of stress, which include acute stress, episodic stress, and chronic stress (Sincero, 2016). Acute stress occurs over short periods while episodic stress is acute stress that is suffered too frequently, and finally, chronic stress is brought on by long-term exposure to stressors (Sincero, 2016). Overall, these factors combine to make stress a severe problem in America today with 75% of Americans reporting that they experienced at least one symptom of stress within the past month (Anderson, et al., 2015). Since such a significant portion of Americans suffer from symptoms of stress, finding a suitable replacement for the medications they take can go a long way in allowing people to combat stress without the adverse side effects of drugs (Lindsey, 2009).
Anxiety
Anxiety is defined as a combination of both mental and physical manifestations, which occur when no specific or significant danger is present (McCue & McCue, 1984).Anxiety disorders have been said to affect 30 % of adults in the United States, and it has been reported to cost more than $22.84 billion regarding healthcare services (Folk & Folk, 2015). It has also been found that about 65% of North Americans take prescription medications daily, with 3.3 Billion prescriptions filled in America in 2002 (Folk & Folk, 2015). This is significant as it signifies how much of a large population anxiety affects in the United States. Currently, the main way that people usually treat anxiety is through the use of antidepressants such as tricyclic, selective serotonin reuptake inhibitors, venlafaxine and more (Gorman, 2003).The use of these drugs has been shown to causes effects such as hypotension, edema, blurred vision and even constipation (Gorman, 2003). Thus, the combination of a large population of the US being affected by anxiety with the fact that anti-anxiety drugs have such harmful effects leads to the finding of an alternative medication that much more important for the US population.
Depression
Depression is when a person feels pressed down upon and is also referred to as sad, blue, down, or simply lowering of mood or spirits (Kanter, Busch, Weeks, & Landes, 2008). Depression is when a person feels sad and emotionally unstable, sometimes for no reason and often because of traumatic events or situations in their lives. Looking at some causes of depression, it has been shown that those with higher depression scores have more frequent and vivid negative images in their brain, and also showed to have a greater proportion of negative about positive images (Weblau, Cloos, Hofling, & Steil, 2015). Thus in their heads, those with depression usually have negative instead of positive thoughts and ideas, and this leads to them feeling down or blue. Some other causes of depression in order from most to least prevalent have been reported to be difficulties within the family; occupational stress, unspecified further stress, traumatic events, depressive disorder and finally unspecified illnesses have been shown to be some causes of depression (Lauber, Falcato, Nordt, & Rossler, 2003). More than 50% of the reported cases of depression were shown to be because of difficulties within the family, which highlights what an important role the family of a person can play in influencing the mood of a person. Causes of depression can also be different regarding being a female or male. Although the causes of depression are similar for both sexes, gender inequalities in economic standing are seen as a cause of depression in women, while gendered patterns of social relationship appear to put men at a disadvantage (Elliott, 2008). Antidepressant medication has been used to treat this mental health disease and with this drug comes adverse side effects. Antidepressants have been proven to cause negative immunoregulatory effects, which may lead to other diseases and disorders (Maes, et al., 1999).This fact makes it crucial to find an alternative to antidepressant medication in a view to allowing patients to be able to be cured of this disease. It will be examined how exercise has an impact on mental health, and specifically different types of exercise within the following section.
Exercise
Physical activity has also been seen to cause improved mental health when a person engages in it (Taylor, Sallis, & Needle, 1985). Exercise has also been shown to lead to some different advantages. Specifically, exercise could be used as an alternative to drugs. When exercise was compared with drug treatment it was found that it was more cost effective, there are no side effects, and exercise has also been shown to have anti-depressant, anti-anxiety and an improvement in mood effect on the human mind (Byrne & Byrne, 1993). This is crucial information, as it provides evidence for how exercise overall can have positive effects on severe mental health problems such as depression and anxiety. The following sections will examine exercise more specifically, looking at what affect both acute and chronic bouts of exercise will have on the specified mental disorders, and specifically look at the difference between anaerobic and aerobic exercise.
Acute bouts of exercise
As defined earlier acute bouts of exercise consists of a single day of exercise or a single session, rather than a series of exercises. The type, intensity, and length of these exercises will also be examined to see the effect it has on the three aspects of mental health. Acute bouts of steady-state exercise have been shown to have a positive effect on cognition and have been linked to improvements in response speed, response accuracy, and higher-order decision-making processes (Tomporowski, 2003). The study also found that if the bouts of exercise were too much time it led to dehydration, which resulted in adverse effects on cognition such as impaired information processing and cognition (Tomporowski, 2003). Thus, if a person can have a higher level of cognition, it will most likely lead to improvements in their mental health, specifically in reducing anxiety, depression and negative mood (Sharma, Madaan, & Petty, 2006).
Acute exercise has also been shown to have an influence on how well a person can sleep. Directly after a bout of acute physical exercise under hypoxia, mood state, reaction time, and sleep ability displayed improvements in normal healthy male volunteers (Anderson, et al., 2015). Acute bouts of moderate-intensity aerobic exercise have also been shown to reduce pre-sleep anxiety and improve sleep in patients who suffer from chronic primary insomnia. (Passos, et al., 2010). Resistance, aerobic and interval training were examined with the conclusion indicating that these different forms of exercise all led to increased maximum oxygen consumption, increased muscular strength, and led to overall improved sleep patterns (Esteves, Ackel-Delia, Tufik, & Mello, 2014). Now that the effects of acute exercise have been examined, its time to talk about how acute bouts of exercise affects stress levels in a person.
Effect of Acute Exercise on Stress
Stress was previously defined to the subject, to stress or strain, to overwork or fatigue a person (Butler, 1993). Higher levels of acute fitness have been shown to result in the reduction of elements such as muscle tension, heart rate and perceived work stress in a study examining teachers and the effect of acute aerobic fitness on their physiological stress response at work (Ritvanen, Louhevaara, Helin, Halonen, & Hänninen, 2007). Now that the relationship between acute exercise and stress has been established, it is time to examine the impact that aerobic and anaerobic forms of exercise have on stress levels in a person.
Acute aerobic exercise and stress
A single session of aerobic exercise has been found to ameliorate the postprandial impairments in arterial function through the reduction of oxidative stress levels (McClean, et al., 2007). It has also been examined that when healthy adults participate in the acute aerobic exercise, it correlates to a beneficial effect on their mental health through the reduction of their stress levels (Kongsjord, 2010). The same study also concluded that the recommended amount of physical exercise needed to obtain the maximum mental health benefits is exercise conducted at a moderate or high intensity, at least five days a week, for 20 minutes, and at a time length of about three weeks (Kongsjord, 2010). Acute physical activity has also been shown to induce an acute state of oxidative stress, through the increase of oxidized molecules in a variety of tissues (Fisher-Wellman & Bloomer, 2009). Stress can also be caused by traumatic experiences that correlate with the development of posttraumatic stress disorder, which is most often seen in war veterans. Acute aerobic exercise has also been linked to post-traumatic stress disorder through the conduction of a study that found that 90% of the participants with the disorder displayed significant reductions in both PTSD symptoms and trauma-related stress severity after undergoing acute bouts of aerobic exercise (Diaz, 2007). Overall, these studies display what a positive effect aerobic exercise can have on reducing levels of stress in a person. Acute aerobic exercise should be used as an alternative method of medication, as antidepressant and antianxiety medication used to treat the disorder right now have adverse side effects (Maes, et al., 1999).The next section will examine the effect acute anaerobic exercise has on stress.
Acute anaerobic exercise and stress
Acute aerobic exercise is not the only way to reduce levels of stress as anaerobic exercises also have stress reducing capabilities. A single high-intensity session of anaerobic exercise was correlated with decreased levels of oxidative stress in participants (Peart, et al., 2013). High-intensity anaerobic exercise has also been linked with acute levels of oxidative stress in participants, which correlates with decreased levels of overall stress (Bloomer & Goldfarb, 2004). Anaerobic exercise has also shown to have a correlation with increases in brain antioxidant capacity (Camiletti-Moiron, Aparicio, & Aranda, 2013). These studies are significant as it highlights specifically how acute anaerobic exercise has a beneficial effect regarding reducing oxidative stress and increasing antioxidant capacity. After doing a single-sprint anaerobic exercise, it was concluded that plasma oxidative stress levels were correlated with a reduction in both cigarette smokers and non-smokers, with non-smokers showing the most significant decline in stress levels (Taito, et al., 2013). This study is significant as it highlights how smoking cigarettes makes it harder to reduce levels of stress through exercise. Furthermore, moderate intensity exercise (60%VO2 max) has been shown to decrease the levels of ox-LDL, by preventing the ox-LDL-mediated suppression of the antioxidant SOD, which can result in decreased levels of stress (McClean, et al., 2007), as shown in Figure 1. Overall, all the different research point to the fact that acute anaerobic exercise is possible to reduce levels of stress in a person, and could be used as an alternative to medication when trying to treat stress.
The effect of acute exercise on anxiety
Now that it has been identified how acute bouts of exercise effect stress, it is time to focus on the relationship between acute exercise and anxiety. Anxiety is defined as a combination of both mental and physical manifestations, which occur when no specific or significant danger is present (McCue & McCue, 1984). In this section, different forms of acute exercise such as aerobic and anaerobic exercise will be examined to figure out it is a relationship with anxiety. Both acute aerobic and resistance exercises have been connected with reductions in state anxiety at about 50 minutes following the completion of the exercise (Hale, Koch, & Raglin, 2002). This is significant as it displays how both aerobic and anaerobic exercise can be equally effective in reducing anxiety. The next section will examine the similarities and differences between the two types of exercise. Acute Aerobic exercise and anxiety
The exercise was studied at 60% maximal oxygen uptake and 80% maximal oxygen uptake, with both intensities leading to a reduction in levels of state anxiety (Cox, et al., 2016). 80% VO2 max displayed a larger degree of improvement in anxiety around 90 minutes post-exercise (Cox, et al., 2016). Using a State-Trait Anxiety Inventory (STAI), it was determined that moderate-vigorous acute and aerobic session of exercise be related to a decrease in the cognitive antecedents of anxiety (Ekkekakis, Hall, & Petruzello, 1999). It has also been concluded that acute aerobic exercise is linked with decreased levels of anxiety in participants (Petruzzello, Landers, Hatfield, & Salzar, 1991). When the duration of the exercise is increased, it displayed superior anxiety reducing effects compared to shorter durations of exercise (Petruzzello, Landers, Hatfield, & Salzar, 1991). There was also no significant difference between the different types of aerobic exercise regarding their anxiety-reducing effects (Petruzzello, Landers, Hatfield, & Salzar, 1991). The significance of this is that a person has the freedom to participate in different forms of acute aerobic exercise to reduce their levels of anxiety and is not just restricted to a specific type of exercise. Now that the effect of acute aerobic exercise has been discussed it is time to see how acute anaerobic exercise affect anxiety levels. Acute anaerobic exercise and anxiety
A variation of intensity and rest time for resistance training resulted in a modest short-term effect on psychological states like anxiety (Bibeau & Mitchell, 2010). It was also concluded that it took around 20-40 minutes after the exercise to detect significant reductions in anxiety (Bibeau & Mitchell, 2010). The effect of different intensities of resistance training was also examined, displaying that low-intensity resistance exercise led to significant reductions in state anxiety while high-intensity resistance exercise resulted in short-duration increases in state anxiety (Bartholomew & Linder, 1997). It has also been concluded that when participants performed 30 minutes of resistance exercise at 60% of their ten-repetition max, it was correlated with a small but significant decrease in state anxiety within 60 minutes following exercise (Bartholomew & Linder, 1997). The significance of this is that when participating in acute anaerobic exercises, participants looking to reduce their levels of anxiety should practice the exercise at lower intensities compared to higher ones, as higher intensities have even shown to increase levels of anxiety (Bartholomew & Linder, 1997). Thus, the evidence displays that acute anaerobic exercise can be used as a replacement for medication treating anxiety.
Acute exercise and depression
Depression as previously defined is a lack of interest and pleasure in daily activities, weight loss, and recurrent thoughts of death or suicide (ADAA, 2016). Acute exercise is related to depression by showing that it can be an effective method for improving mood, with both resistance and aerobic exercise showing benefits regarding reducing the amount of depression a person experiences (Chase & Hutchison, 2015). Now the effects of both aerobic and anaerobic exercise on depression will be examined.
Acute aerobic bouts of exercise and depression
Through the use of POMS-SF (Profile of Mood States-Short form), it was determined that acute sessions of aerobic exercise could result in mood enhancement, and specifically, enhance levels of depression and alternative mood states (Chase & Hutchison, 2015). Patients who have major depressive disorder have also advertised improvements with their disorder through the completion of acute rounds of aerobic exercise (Morrison & J. Ciccolo, 2005).The improvements are generated by an upsurge of their psychological happiness and the competence to regulate their mood in the short-term (Morrison & J. Ciccolo, 2005). These studies exemplify how acute aerobic exercise has a comprehensive and favorable outcome of depression. Next, it will be examined if there is a particular intensity in which exercise shows the greatest effect on depression.
After about 20 minutes of cycling, participants with depressive and/or anxiety disorders displayed a strong reduction in state anxiety and negative affect (Vancampfort, et al., 2008). Specifically cycling at a prescribed intensity of 50% of the max heart rate reserve showed reductions in fatigue, while self-selected intensities revealed a surge in fatigue (Vancampfort, et al., 2008). This is significant, as fatigue has been shown to be positively correlated with depression. Thus, 50% of the max heart rate is around where patients will most likely obtain the greatest depression reducing benefits (Aygunoglu, Celebi, Vardar, & Gursoy, 2015). Since anti-depressive medication has been shown to have adverse side effects, these studies could help explain how acute bouts of aerobic exercise can positively influence depression (Maes, et al., 1999). Specifically, acute bouts of physical exercise have also been shown to result in decreased levels of depression and have been shown to be as potent as antidepressants in treating depression (North, McCullagh, & Tran, 2006). This is very critical as if the effect of the exercise is as significant as antidepressants and it comes with no side effects, then acute aerobic exercise could have the ability to replace anti-depressant medication. Now that the beneficial relationship between acute aerobic exercise and depression has been established, it is time to examine how acute anaerobic exercise influences depression.
Acute bouts of anaerobic exercise and depression
Anaerobic exercise is seen as intense and brief with an example being weight lifting (Salmon, 2001). According to meta-analyses conducted examining the effects of exercise on clinical depression and depression resulting from mental illness. It established that acute bouts of anaerobic exercise led to decreased levels of depression based on eight different nonaerobic activity studies conducted, which had a combination of both acute and chronic nonaerobic exercises (Lynette & Landers, 1998). A single episode of bodybuilding workout (anaerobic) has also been shown to lead to improvements in both depressive and anxiety symptoms, with the results being usually seen about a few hours after the completion of the exercise (Peluso & Andrade, 2005). Another meta-analysis was conducted examining 80 studies, and it concluded that both acute and chronic exercise were shown to be correlated with reductions in the levels of clinical depression, and specifically identified both aerobic and non-aerobic exercises as effective antidepressants (Scully, Kremer, Meade, Graham, & Dudgeon, 1998). This finding is very significant as it provides clear evidence that it is possible to use multiple different types of exercise as viable antidepressants, and specifically acute bouts of anaerobic exercises can lead to a reduction in depression levels of a person (Scully, Kremer, Meade, Graham, & Dudgeon, 1998). The main reason that antidepressants need to be replaced is that they are usually costly, ineffective, and display unpleasant side effects including fatigue, addiction, and other complications. This fact combined with the evidence linking acute anaerobic exercise and antidepressant effects, the cost and no adverse side effects make this form of exercise a viable option to be used to treat depression.
Chronic Bouts of Exercise
As earlier defined, chronic bouts of exercise are those extended by a vast amount of time. Chronic bouts of exercise include sprinting on a treadmill multiple times a week, a lifting program lasting multiple days, weeks, or any physical activity in which multiple sessions of it are done (Liu, et al., 2000).Chronic bouts of exercise have also been shown to reduce resting heart rates and blood pressures (Wang, Chauying, & Chen, 1997). Chronic exercise has also been linked with attentional networks with the relationship being that it leads to a positive effect of exercise on the executive network; it also showed that exercise can result in improvements in attentional control in healthy young adults (Perez, Padilla, Parmentier, & Andres, 2014). Chronic bouts of exercise have many different benefits on the human body, and another advantage that has been shown to be linked with physical exercise is increased resting NKCA after continuous resistance training suggested that immunity had been improved (McFarlin, Flynn, Phillips, Stewart, & Timmerman, 2004). Thus, chronic bouts of exercise have been shown to affect many different parts of a person, and this section will specifically look at how chronic bouts of exercise effect stress, anxiety, and depression.
Chronic exercise and stress
Chronic exercise has been shown to enhance critical measures of spatial learning, which can lead to fewer levels of stress based on a study conducted examining the effect of chronic physical exercise and stress on different types of memory in rats (Mello, Benetti, Cammarota, & Izquierdo, 2008). This next section will specifically look at how both aerobic and anaerobic exercise effect stress, and if they could be used as a treatment for stress disorders.
The effect of chronic bouts of aerobic exercise on stress
An association has been established between chronic bouts of aerobic exercise and lower rates of atheroma, which increases the risk of thrombosis (Elaine, 1988). This is significant as thrombosis can cause higher levels of stress because it is a condition that causes clotting of the blood in the circulatory system (Elaine, 1988). Examining how different intensities of exercise are correlated with stress, it has been concluded that moderate-to-high intensity exercise causes a significantly elevating endogenous antioxidant defenses. It also showed that regular to moderate-to-high-intensity exercise has been demonstrated to protect against chronic oxidative stress (Parker, McGuckin, & Leicht, 2014).The chronic aerobic training program has also shown remarkable up-regulation in antioxidant enzymes which can help lead to the minimization of oxidative stress (Oliveira, et al., 2012). Overall, these studies indicate that chronic bouts of aerobic exercise can be very beneficial regarding reducing stress levels in people, specifically leading to less oxidative stress and helping to improve the overall mood and response to stressful situations largely. To conclude these,it is evident that chronic bouts of aerobic exercise could be an option regarding replacing drugs for the treatment of stress disorders.
The effect of chronic anaerobic exercise on stress
There are multiple forms of chronic exercise, which include not only the aerobic bouts of exercise but also an anaerobic bout of exercise. They do not require as much oxygen as aerobic exercises such as weight lifting or running. Chronic bouts of anaerobic exercise have likewise been presented to induce adaptations that will be able to reduce the amount of exercise-induced oxidative stress in a person (Bloomer & Goldfarb, 2004).The same study also concluded that chronic anaerobic exercise could stimulate increased antioxidant production when the anaerobic exercise is of a sufficient intensity and duration (Bloomer & Goldfarb, 2004). This is significant as it shows how chronic anaerobic exercise has been demonstrated to lead to fewer levels of stress in people, and produce antioxidants, which can help to relieve the overall stress in a person. Since stress is treated using antidepressant medication, the side effects may cause negative immunoregulatory effects, which may progress to other disorders and diseases (Maes, et al., 1999). Thus in combination with the evidence displayed providing a beneficial correlation between chronic anaerobic exercise and stress, and the adverse side effects that the medication currently being prescribed to people has been shown to have led to this type of exercise being a suitable replacement regarding treating stress.
Chronic exercise and anxiety
Regardless of the anxiety, measures taken (trait/state, behavioral, etc.) and the type of exercise regimen (acute or chronic), it has been shown that exercise leads to the reduction of anxiety levels in a person (Scully, Kremer, Meade, Graham, & Dudgeon, 1998). This is significant as it shows that overall exercise leads to improvements in anxiety levels in a person, and specifically indicates that chronic exercise can have a beneficial effect on anxiety. This next section will examine the difference between aerobic and anaerobic exercise and if they could be a viable replacement to treat anxiety in a person.
The effect of chronic aerobic exercise on anxiety
Chronic bouts of aerobic exercise do not only have an effect on stress, but they also have an effect on the amount of anxiety person experiences. Chronic aerobic exercise has been seen to lead to a significant reduction in trait anxiety, especially when the training program exceeded nine weeks in length (Petruzzello, Landers, Hatfield, & Salzar, 1991).Jogging has also been shown to be more beneficial regarding reducing stress compared to walking (Jayakody, Gunadasa, & Hosker, 2012). Chronic aerobic exercise has also been seen to lead to significant reduction in anxiety-related indexes like latency, time spent in peripheral squares, and more (Pietrelli, Lopez-Costa, Goni, Brusco, & Basso, 2012). Chronic physical activities including aerobic exercise have also been shown to lead to the reduction of oxidative stress in the hippocampus. (Moylan, et al., 2013). The paper also examined the optimal exercise intensity needed to be able to get psychological benefits, and it found that moderate intensity exercise was shown to have the best effects on a person (Mackay & Neill, 2010). Table 1 is comparing pre-exercise anxiety and post-exercise anxiety, and the results indicate that in every type of aerobic exercise it led to reduced levels of anxiety.
Overall, all of these studies help form the conclusion that chronic bouts of aerobic exercise can be very beneficial for people trying to relieve their stress levels, and would be an excellent replacement for the anti-anxiety drugs being administered today, which come with a multitude of side effects. Physical symptoms of anti-anxiety drugs have been shown to include nausea, headaches, dizziness, trembling, and others while psychological symptoms include poor concentration, emotional distress and lack of motivation (Haslam, Brown, Atkinson, & Haslam, 2004). Studies have also been conducted examining the relationship between aerobic exercise groups compared to other forms of anxiety treatment (group therapy, relaxation,
Pharmacotherapy), and it provides strong evidence for the anxiolytic effects of aerobic exercise. Thus to avoid these unnecessary side effects, people should use chronic aerobic exercise as a way of dealing with anxiety.
The effect of chronic anaerobic exercises on anxiety
Chronic aerobic exercise is not the only type of exercise that has shown benefits regarding reducing the amount of stress person experiences. Chronic anaerobic exercise is also possible of lessening the level of stress in a person. Meta-analyses found that both aerobic and anaerobic exercise led to a reduction of anxiety, but aerobic exercise had a larger effect on reducing anxiety symptoms in people (Petruzzello, Landers, Hatfield, & Salzar, 1991). The meta-analysis also found that exercise lasting 0-20 minutes showed significantly smaller effect sizes compared to exercise that lasted 21-30 minutes (Petruzzello, Landers, Hatfield, & Salzar, 1991). Chronic anaerobic exercise has been shown to result in significant reductions in both anxiety scores and symptoms (Jayakody, Gunadasa, & Hosker, 2012).The same study also concluded that moderate to hard exercise leads to a significant reduction in anxiety symptoms compared to very light anaerobic exercise (Jayakody, Gunadasa, & Hosker, 2012). These studies help support the claim that chronic bouts of anaerobic exercise have beneficial effects on anxiety levels in a person, and just like the other types of exercise is possible to replace anti-anxiety medication.
By making a comparison between the benefits of chronic anaerobic exercise and antidepressant medication, it was found that the exercise caused a considerable degree of anxiety reduction very close to the same level of the antidepressant medication (Jayakody, Gunadasa, & Hosker, 2012). Thus depending on the type of exercise a person likes, they could choose to do chronic bouts of anaerobic or aerobic exercise in order to use it as a treatment for anxiety.
Chronic exercise and depression
Depression as previously stated is a lack of interest and pleasure in daily activities (ADAA, 2016). The relationship between chronic aerobic and anaerobic exercise will be examined in the following section, with the main goal of observing if it can be used as a treatment for depression.
Effect of chronic aerobic exercise on depression
Now that chronic aerobic and anaerobic exercises have been shown to have a beneficial effect on mental health aspects of anxiety and stress, it is time to examine the effect it has on depression. Chronic aerobic exercise has been shown to cause reductions in depression scores using a Chinese version of the Beck depression inventory-II (Liu, Chang, & Yeh, 2015). Chronic aerobic exercise has also been seen to lead to a reduction in the peripheral COMT (S-COMT) activity in depressed patients, and this is significant as higher COMT activity has been observed in depressive people compared to non-depressed people (Carneiro, et al., 2016). Another study was conducted examining how electroconvulsive therapy (ECT) and chronic aerobic exercise training (AET) affected patients suffering from major depressive disorder (Salehi, Hosseini, Haghighi, Kirov, & Brand, 2016). It concluded that depressive symptoms showed a reduction for both methods, and showed the most significant decrease occurred when a combination of both ECT and AET were used on the participants, compared to when only one method was used (Salehi, Hosseini, Haghighi, Kirov, & Brand, 2016). This is very significant as it shows chronic aerobic exercise is correlated with a reduction in depression. If combined with other forms of treatment like electroconvulsive therapy can lead to significant reductions in depressive symptoms. Aerobic exercise has also resulted in a reduction of depressive symptoms, with anaerobic exercise showing little to no effect on depression (Penninx, et al., 2002). Thus, overall these studies concluded that chronic aerobic exercise effects depression through reducing depression scores on depression measures, reducing peripheral COMT, and reducing depressive symptoms. These studies display how chronic aerobic exercise can have a significantly positive effect on depression in patients, and should be used as a replacement for anti-depressive drugs and the negative side effects that accompany it.
Effect of chronic anaerobic exercise on depression
Chronic anaerobic exercise has also been shown to have a significant force regarding acting as an anti-depressant. Progressive resistance training in subjects who are depressed elders revealed that this type of exercise could be an efficient antidepressant while also improving strength, morale and the quality of life of the subjects (Singh, Clements, & Fiatarone, 1997). It has also been found that an anaerobic program like bodybuilding was correlated with a reduction in levels of depression in the inpatients, compared to the aerobic session of exercise (Palmer, Palmer, Michiels, & Thigpen, 1995). This study highlights the importance that the specific type of exercise has on specific people, in which this case it was about substance abusers and how anaerobic exercise showed a greater potential to decrease their depression levels rather than the aerobic exercise. Although these studies display a correlation between chronic anaerobic exercise and depression, they are usually seen mainly in drug abusers and most of the studies that were examined showed a minimal overall impact on depression. Discussion
This paper has done an extensive job of examining how different forms of exercise affect three various aspects of mental health, which include depression, anxiety and stress. Specifically, the question that was trying to be answered was that could be a viable replacement to drugs regarding treating mental health problems. All of the evidence displayed shows that all types of exercise, whether chronic, acute, anaerobic or aerobic was correlated with increased mental health benefits specifically looking at depression, anxiety, and stress. Although certain methods of exercise have been shown to have a stronger effect than others, and the relationship between them will be examined.
As shown in Table 1, it is possible to conclude that acute sessions of aerobic and anaerobic exercise had a positive effect on the specified elements of mental health, specifically showing that no significant difference existed between acute/chronic and aerobic/anaerobic exercises and reducing stress. Also, looking at anxiety, the same conclusion can be made, in which there no significant difference between aerobic and anaerobic exercise was regarding reducing anxiety. This is usually, especially when the exercise is conducted in a continuous manner of at least nine weeks, it leads to a significant reduction in trait anxiety.
Finally, while examining depression, it is possible to see how chronic aerobic exercise had a larger impact regarding reducing depression compared to anaerobic bouts of exercise, as some studies have said that anaerobic exercise has no effect on depression (Penninx, et al., 2002).
Focusing on similarities between acute sessions of aerobic and anaerobic modes of exercise, it is possible to see that stress was related to the reduction of oxidative stress levels ( (McClean, et al., 2007) , (Bloomer & Goldfarb, 2004). Focusing on anxiety, it is possible to conclude that in both forms of exercise the longer the duration of the workout the greater the beneficial effect it will have on levels of anxiety (Petruzzello, Landers, Hatfield, & Salzar, 1991). Depression demonstrated that both types of exercises have been identified as effective antidepressants (Scully, Kremer, Meade, Graham, & Dudgeon, 1998). Now looking at chronic sessions of exercise it is possible to conclude that there were no obvious similarities between aerobic and anaerobic exercise on stress, a similarity in anxiety was that they both led to the reduction of stress levels. This is significant because it shows how aerobic and anaerobic are not that far from each other.
Examining the effect that acute exercise had on stress and anxiety, it's possible to determine some similarities such as the benefits of acute exercise were reviewed to be the highest at (60%) moderate intensity (McClean, et al., 2007), while anxiety also displayed the most powerful effects around an (80%) moderate-to-high intensity degree of exercise (Cox, et al., 2016). For depression, exercise was examined to be most beneficial at about 50%, classifying it as moderate intensity, which makes it more similar to stress than anxiety. Overall, the results have helped answer the main question of this paper, which was to see if exercise could be used as a viable replacement for drugs, and all forms of exercise except chronic anaerobic exercise showed to be possible to replace drugs and their adverse side effects. This is very significant as since there are adverse side effects usually associated with pharmaceutical drugs (Gorman, 2003), (Maes, et al., 1999), using the discussed methods of exercise could end up being cost efficient and healthiest approach to dealing with mental disorders. Conclusion
This paper focused on three aspects of mental health, which included stress, anxiety, and depression. These aspects of mental health were examined trying to find a correlation between different forms of physical activity and improvements in the three aspects of mental health. Numerous research articles and meta-analysis papers to determine if physical activity could be a viable replacement for pharmaceutical drugs and the results showed that all the different forms of exercise were positively correlated with improvements in mental health. Specifically, only the effect of chronic anaerobic exercise on depression was shown not to have a significant effect based on recent research articles. The difference between aerobic (air) and anaerobic (no air) exercise modes displayed similar types of results for the different durations of exercises examining the three different aspects of mental health. Specifically, the main difference between these two kinds of the exercise was studied in chronic bouts of anaerobic exercise, as aerobic exercise showed a significantly greater reduction of depression and depressive-like symptoms. Overall, this information could help establish exercise as a viable treatment for numerous mental disorders including those not examined in this paper and would be able to treat them without the adverse side effects that drugs that treat mental illness have on patients.
Future Implications
Regarding future research that can be done on this topic, it is possible to see that more studies should be conducted to assess the effect of anaerobic exercise in depression as not enough studies were conducted examining this relationship. Also, studies should be performed examining how participating in both chronic and acute bouts of aerobic and anaerobic exercises in succession to each other would have an effect on different aspects of mental health. Finally, experiments should be conducted in a closed experimental area to examine other factors of improvements of mental health because of physical exercise. References
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Appendices
Appendix 1
Table 1: Aerobic and anaerobic exercise and its influence on mental health
Exercise group Pre-exercise anxiety Post-exercise anxiety Effect size n M SD Skew Kurt M SD Skew Kurt d
Road Cycling 1.78 0.54 0.59 −0.09 1.42 0.32 0.94 1.65 0.84* 19
Mountain Running 1.56 0.33 −0.24 −0.56 1.51 0.39 0.71 −0.16 0.14 15
Orienteering 1.62 0.50 0.92 0.25 1.56 0.33 −0.11 −1.22 0.14 15
Cross-Country Running 1.52 0.55 1.44 2.41 1.40 0.44 1.05 0.26 0.24 15
Boxercise 1.79 0.39 0.19 −1.08 1.41 0.38 0.54 −1.06 0.99* 9
Mountain Biking 1.68 0.46 0.07 −1.72 1.31 0.23 0.26 −1.51 1.02 9
Total 1.64 0.48 1.64 0.48 1.44 0.36 1.44 0.36 0.47 82

Appendix 2 Figure 1 Relationship between anxiety scores and time