Morning vs Evening Exercise generates strong opinions in every gym and fitness forum. Most of those opinions are personal preference wearing the costume of universal truth.
Both approaches have produced exceptional results in the right context. Neither is universally superior. The question is which context matches yours.
What makes this comparison matter for men specifically is that training methodology shapes not just the body but daily energy, injury risk, and psychological state. The wrong approach doesn’t just slow progress — it can create setbacks that take months to recover from. Getting it right saves time that doesn’t come back.
What follows compares these approaches across five criteria that matter more than opinion: effectiveness for specific goals, injury risk, time efficiency, long-term sustainability, and adaptation potential.
Worth grounding this in the actual chronobiology before anything else, because most of the internet debate skips it entirely. Human physical performance follows a circadian rhythm independent of habit or preference — core body temperature, which correlates strongly with muscular performance, typically bottoms out around 4-5 AM and peaks somewhere between 4 PM and 8 PM. Thomas Reilly and Ben Edwards documented this pattern across decades of chronobiology research at Liverpool John Moores University, and the practical implication is blunt: the body is not neutral about when it performs best. It has a built-in preference, and that preference leans toward the evening for almost everyone — the disagreement in the research is about how large that gap is and how much training itself can shrink it.
WHAT IS MORNING?
The compliance finding is the strongest single argument for morning training, and it’s been replicated enough times to take seriously. A widely cited analysis tracking gym check-in data (the kind gym-chain researchers publish rather than peer-reviewed labs, worth flagging) consistently shows morning exercisers missing fewer sessions over a year than evening exercisers, largely because morning slots aren’t competing with work crises, social obligations, or the accumulated fatigue of a full day. The mechanism isn’t physiological superiority. It’s calendar position. Nothing gets scheduled at 5:30 AM that outranks a workout; plenty gets scheduled at 6 PM that does.
The circadian-entrainment claim has real mechanistic backing too. Morning light exposure, which naturally accompanies most outdoor or window-adjacent morning training, is one of the strongest external cues (zeitgebers) for the suprachiasmatic nucleus — the brain’s master clock. Exercise itself adds a secondary phase-shifting signal. A 2019 study by Youngstedt and colleagues in the Journal of Physiological Anthropology found that morning exercise produced a modest phase-advance in circadian rhythm (shifting the body clock earlier), which can help with sleep onset in people who run naturally late — though the same study found evening exercise, at sufficient distance from bedtime, didn’t meaningfully disrupt rhythm in most subjects either, undercutting the stronger claims made about evening training destroying sleep.
Evening exercise — training between 4pm and 8pm — aligns with the body’s natural circadian performance peaks. Core body temperature, muscle glycogen availability, reaction time, strength output, and pain tolerance are all measurably higher in the late afternoon. Research consistently shows athletes perform 3-5% better on strength and power measures in the afternoon compared to morning. The primary downside: exercise within 2-3 hours of bedtime elevates core temperature and cortisol, which can delay sleep onset.
| Morning | Evening | |
|---|---|---|
| Performance | Marginally higher fasted fat oxidation | 3-5% better strength/power output (afternoon chronobiology peak) |
| Body state | Sympathetic activation to start the day | Higher core temp, glycogen availability, reaction time |
| Downside | None significant noted | Within 2-3 hours of bed, can delay sleep onset |
| Compliance | Generally higher | Not addressed |
The performance data behind that 3-5% figure comes from a substantial body of chronobiology work, most notably a comprehensive review by Chtourou and Souissi published in 2012 in the Journal of Strength and Conditioning Research, synthesizing dozens of studies on diurnal variation in athletic performance. The consistent pattern: strength, power, sprint performance, and flexibility all trend higher in the late afternoon window, generally 16:00-19:00, coinciding with peak core body temperature. The mechanism runs through temperature-dependent enzyme kinetics and nerve conduction velocity — muscle and nerve tissue simply function more efficiently a few degrees warmer, which is also why a proper warm-up partially closes the morning performance gap by artificially raising core temperature before the peak window arrives naturally.
On the sleep-disruption question, the honest research picture is more nuanced than the blanket warning suggests. A 2019 systematic review by Stutz, Eiholzer, and Spengler in Sports Medicine, pooling 23 studies on evening exercise and sleep, found that vigorous evening exercise finishing within one hour of bedtime did modestly reduce sleep quality and delay sleep onset — but exercise finishing more than one hour before bed, even moderate-to-vigorous intensity, showed no significant negative effect on sleep architecture in the pooled data, and in several individual studies actually improved slow-wave sleep. The blanket “never train within 3 hours of bed” rule that circulates online overstates the actual buffer most people need; the real inflection point in the data sits closer to 60-90 minutes for vigorous sessions, not three hours.
MORNING VS EVENING EXERCISE: BREAKING DOWN THE REAL DIFFERENCES
The gap between Morning and Evening Exercise runs deeper than the quick-comparison version. The table below is the orientation pass. The detail that actually helps decide is in the breakdown that follows it.
DETAILED BREAKDOWN: WHERE EACH ONE WINS
Effectiveness for Specific Goals
Morning produces its best results when applied to the training goals that actually match its mechanism. Knowing what it’s optimized for — and what it isn’t — prevents the common mistake of using the right tool on the wrong problem. Men who match training approach to actual goal see dramatically faster progress than those who don’t.
For pure fat-oxidation goals in a fasted state, morning has a modest physiological edge — a well-cited 2010 study by Van Proeyen and colleagues in the Journal of Physiology found fasted morning training increased the proportion of fat used as fuel during exercise and improved insulin sensitivity over a six-week protocol compared to the same training fed. The effect on total body fat over time, however, was not dramatically different from fed training once total calorie intake was matched — meaning fasted morning cardio is a legitimate metabolic-flexibility tool, not the fat-loss superweapon it gets marketed as.
Evening Exercise is optimized for different outcomes entirely. The overlap between what each approach does well creates the illusion they’re interchangeable, but the differences show up fast once you’re past the beginner stage. Intermediate and advanced trainees need to be deliberate about matching methodology to objective.
For strength and hypertrophy specifically, the evidence leans evening. A 2016 study by Küüsmaa and colleagues in Chronobiology International had two groups of trainees follow identical resistance programs for 24 weeks, one training exclusively in the morning, one exclusively in the evening. The evening group showed significantly greater strength gains in leg press and slightly greater hypertrophy, consistent with the higher force output available during the late-afternoon performance window across two dozen weekly sessions compounding into a measurable difference. Worth noting: a subset of subjects who consistently trained morning for the full 24 weeks showed a partial adaptation — their morning performance gap narrowed over time, supporting the idea that the body can train itself to perform closer to peak even outside its natural window, just not fully close the gap.
Injury Risk Profile
Every training approach carries injury risk, and Morning has its own specific patterns. Knowing where injuries tend to happen — acute and chronic both — is what lets someone actually implement preventive measures. Most training injuries are overuse injuries from poor load management, not the methodology itself.
Morning training’s primary risk is tissue stiffness and reduced range of motion at the start of the day. Synovial fluid viscosity is higher shortly after waking, and connective tissue is measurably less extensible in the first hour after rising — which is why morning training protocols that skip an adequate warm-up show disproportionately higher rates of muscle strain in some observational data, particularly in explosive or heavy-loaded movements attempted cold. A longer, more deliberate warm-up (10-15 minutes rather than 5) meaningfully closes this gap.
Evening Exercise has a different injury profile. Some approaches carry higher acute risk; others produce more chronic overuse issues. The safest approach is always the one implemented with proper progression, adequate recovery, and an honest read on readiness.
Evening training’s main risk isn’t the session itself — it’s accumulated fatigue from a full day of work, sitting, cognitive load, and dehydration reducing coordination and judgment during heavier lifts. A man who’s been at a desk for nine hours and skipped lunch is walking into a strength session with compromised proprioception even though his tissue is warmer and his hormones more favorable. The performance ceiling is higher in the evening; the floor, on a bad day, can be lower too.
Time Efficiency
How much weekly training time Morning requires for meaningful results matters a lot for men with demanding schedules. Some approaches deliver results in 3-4 hours a week; others need 6+. The most time-efficient option isn’t always the most effective one, but for most men, whatever fits the schedule reliably is what ends up producing results.
Morning sessions are almost always shorter in practice, not because the ideal program is shorter but because the clock imposes a hard stop — work starts at a fixed time regardless of how the set went. This constraint is double-edged: it forces efficient programming (no wasted rest periods, no phone scrolling between sets) but also caps how much volume can realistically be fit in on a demanding lifting day.
Evening Exercise has its own time demands. Session length matters, but so does frequency, warm-up requirements, and recovery time between sessions. A protocol needing 4 sessions a week with full recovery days between them has a very different schedule footprint than one demanding daily practice.
Evening windows tend to be more elastic but less reliable — there’s no hard external stop, so a session can run as long as needed, but competing evening obligations (family dinner, kids’ activities, social plans) derail evening sessions far more often in practice than morning sessions get derailed by anything, which is the flip side of the compliance data cited earlier.
Long-Term Sustainability
Doing Morning at 50? At 60? Long-term sustainability matters because the best training approach is the one maintained for decades. Not the one producing the fastest results for 6 months before burnout or injury sets in. Consider joint health, motivation, variety, and adaptability to aging.
Evening Exercise’s sustainability profile depends on similar factors. Some training approaches age well; others need modification as the body changes. The most sustainable protocols build in variation, manage volume intelligently, and don’t depend on maximal effort every single session.
Age interacts with this decision more than most training guides acknowledge. Cortisol’s natural circadian peak in the 6-8 AM window flattens somewhat with age, and older trainees often report needing longer warm-ups regardless of time of day as tissue elasticity declines. Testosterone’s diurnal rhythm — highest in the early morning, declining through the day — also flattens with age, meaning the theoretical “anabolic window” advantage some men cite for morning training is considerably smaller past 50 than it is at 25, a point that rarely makes it into the popular “train fasted for testosterone” advice aimed at all ages indiscriminately.
Adaptation Ceiling
Every training approach hits a point of diminishing returns — Morning is no exception. Knowing where that ceiling sits is what lets someone plan transitions ahead of time. Some men ride a single approach for years; others need to periodically shift methodology to keep progressing. Knowing when most of the available adaptation has already been extracted is what prevents the frustrating plateau.
Evening Exercise has its own adaptation ceiling. How long productive training lasts before plateauing depends on starting point, genetics, recovery capacity, and how well the programming is managed. When progress stalls, the fix is usually a programming adjustment. Not abandoning the approach entirely.
One underappreciated finding from the circadian literature: the performance gap between morning and evening narrows with consistent training at either time, a phenomenon researchers call “training-induced phase adaptation.” Facer-Childs and Brandstaetter documented this in a 2015 Current Biology paper — habitual morning exercisers showed smaller morning-versus-evening performance gaps than sedentary controls, suggesting the body partially entrains its performance rhythm to match training schedule over months of consistency. Practical read: the “evening is objectively better” argument is strongest for someone just starting out or switching cold, and weakens the longer someone has consistently trained at a given time.
STRENGTHS AND WEAKNESSES OF MORNING
Strengths:
- Effective for its specific target adaptations
- Well-understood when properly programmed
- Scalable to different fitness levels
- Supported by both research and decades of practical application
Weaknesses:
- Not optimal for goals outside its primary adaptation
- Requires proper programming to avoid common pitfalls
- May need periodization to prevent staleness and overuse
- Can be misapplied by those following generic protocols
STRENGTHS AND WEAKNESSES OF EVENING EXERCISE
Strengths:
- Targets different adaptations that may better match your goals
- Provides variety that supports long-term adherence
- Can address limitations that the alternative creates
- Growing body of evidence supporting its applications
Weaknesses:
- Less effective for specific goals that favor the alternative
- Own set of injury risks and programming demands
- May require more knowledge to implement effectively
- Results depend heavily on individual response and execution
WHEN TO CHOOSE MORNING
Morning training wins on compliance and on hormonal alignment with the testosterone/cortisol ratio that favors muscle-building signals. Building a habit meant to last years? Morning is usually the sustainable choice. It also delivers a psychological win before the day’s demands even show up.
Choose Morning when the primary goal lines up with its strengths, when the knowledge (or coaching) to program it effectively is in place, and when schedule and recovery capacity can support its demands. Also worth choosing if it’s genuinely enjoyable — training someone looks forward to beats theoretically superior training they dread, every time, over a long enough horizon.
WHEN TO CHOOSE EVENING EXERCISE
Evening training wins on raw performance output. Competing, testing maxes, or training for athletic performance where every percent matters — train in the late afternoon, when the body’s peak physical performance window is actually open. Just finish by 7pm to protect sleep.
Choose Evening Exercise when the goals are better served by its specific adaptations, when there’s been a plateau with the alternative, or when practical considerations (time, equipment, enjoyment) favor it. Also worth considering during specific training phases where its strengths line up with current priorities.
A COMPOSITE CASE: TWO MEN, TWO WINDOWS
Take a guy we’ll call Ray. Thirty-eight, powerlifting-focused, competing twice a year. He trained mornings for years out of habit — it fit his old job. When he switched to evening sessions to prepare for a meet, his gym log showed something he hadn’t expected: his working sets at the same relative intensity felt meaningfully easier, and over an eight-week prep block his squat and deadlift numbers on identical programming moved up faster than the equivalent block a year earlier, trained in the morning. He didn’t change his program. He changed the clock, and the clock mattered.
Contrast that with a guy we’ll call Damon. Forty-one, general fitness goals, three young kids, chaotic evenings that involve dinner, homework, and bedtime routines that reliably eat any exercise window after 5 PM. Damon tried evening training for six weeks based on the performance data and missed eleven of eighteen planned sessions — not from lack of will, from a schedule that structurally couldn’t hold the slot. He switched to 5:45 AM, before the house woke up, and completed 51 of 54 planned sessions over the following three months. His per-session performance was, by his own report, worse than his evening attempts had been. His actual physical results over the quarter were considerably better, because a slightly-worse session completed beats a theoretically-optimal session skipped, every single time. The Chtourou performance data was never wrong for Damon. It just wasn’t the variable that mattered most for him.
Both men made adjustments the research would actually endorse, even if neither of them read a single study to get there. Ray’s meet prep leaned into the performance data because his goal — maximal output on a specific day — is exactly the goal the circadian literature speaks to most directly. Damon’s schedule made the performance data close to irrelevant; his limiting factor wasn’t peak force output; it was whether the session happened at all. Different bottleneck, different correct answer, same underlying science.
SLEEP DISPLACEMENT: THE VARIABLE THAT WRECKS MORNING TRAINING SILENTLY
The most common failure mode with morning training isn’t the training. It’s what happens to the hours before it. A man who decides to start training at 5:30 AM and simply bolts that onto his existing 11 PM bedtime hasn’t added a healthy habit — he’s subtracted ninety minutes of sleep, night after night, and is now running a chronic sleep debt in the name of fitness. Matthew Walker’s sleep research at UC Berkeley, and a large body of work before it, consistently links sub-7-hour sleep with reduced muscle protein synthesis, elevated next-day cortisol, and measurably worse strength and power output — meaning a sleep-deprived 5:30 AM session can, over weeks, produce worse training outcomes than a well-rested 6 PM one, independent of the circadian performance data discussed above.
The fix isn’t complicated but it’s the step almost everyone skips: shifting a bedtime earlier by the same amount the wake time moves earlier, before starting the new training schedule, not after. Two weeks of earlier bedtime adjustment before the first 5:30 AM alarm prevents the sleep-debt spiral that sinks most attempts at morning training within the first month. Men who add the early alarm first and plan to “adjust bedtime later” almost never actually adjust it — the debt just accumulates and gets blamed on the training instead of the missing sleep.
THE PRACTICAL REALITY CHECK
Here’s what most articles about exercise timing leave out: the research on optimal training times assumes all other variables are equal. They are not. A guy training at 5 AM because a podcast told him it builds discipline, then sleeping 5 hours to make it happen — he’s sabotaging his own recovery, hormonal health, and cognitive function. The best training time that costs sleep is the worst training time. Full stop.
Cortisol patterns matter here. The body naturally produces peak cortisol around 6-8 AM, which theoretically supports morning training intensity. But chronic sleep deprivation from early alarms disrupts that cortisol pattern already, and training during that window ends up adding stress instead of channeling it productively. Evening trainers often have the advantage of being better rested, better fed, and more physically warm — all of which help both performance and safety.
There’s also the meal timing angle. Morning trainers either train fasted, which carries its own trade-offs for strength and hypertrophy, or wake even earlier to eat and digest first. Evening trainers have had multiple meals through the day, glycogen stores topped off, amino acid availability high. For strength and muscle-building goals specifically, the fed state of evening training gives a real advantage that morning training struggles to match without a serious lifestyle rebuild.
One more variable worth naming: blood pressure and cardiovascular strain follow their own daily pattern, and it cuts against morning training for a specific population. A 2015 study by Thosar and colleagues in the European Journal of Applied Physiology found endothelial function (how well blood vessels dilate) was measurably worse in the early morning hours compared to afternoon, part of a broader body of cardiology research explaining why heart attacks and strokes cluster disproportionately in the early morning window generally. This doesn’t mean morning exercise is dangerous for a healthy man in his thirties. It does mean men with existing cardiovascular risk factors — hypertension, family history, prior cardiac events — have a legitimate, evidence-based reason to lean evening rather than morning, a consideration that almost never appears in generic “best time to work out” content.
COMMON MISTAKES MEN MAKE WITH THIS DECISION
- Choosing based on identity rather than goals. Don’t pick a training approach because of the community wrapped around it. Pick it because it serves the specific physical goal. Training methodology is a tool, not a personality trait. Use whatever produces the results actually wanted.
- Switching approaches every 4-6 weeks. Adaptation takes time. Jumping between approaches before either has been given enough time to produce results guarantees mediocre outcomes from both. Commit to one for a minimum of 12 weeks before evaluating anything.
- Ignoring what the body actually responds to. Individual variation in training response is massive. Two men on identical programs get different results. Pay attention to what the body responds to. Not what the internet insists should work. Program accordingly.
- Skipping the warm-up because the session is early. The exact circumstance where a longer warm-up matters most — cold tissue, low core temperature, stiff joints — is the one most men shortcut when they’re already running late for work. This is a leading contributor to morning-session strain injuries and it’s entirely preventable with 10 extra minutes.
- Ignoring the chronotype question entirely. Not every man is wired the same way. Genuine biological “morning types” and “evening types” (chronotypes, driven partly by the PER3 gene variant studied by Simon Archer’s group at Surrey) show measurable performance and mood differences training at their preferred versus non-preferred time. A hard-wired evening chronotype forcing 5 AM sessions is fighting biology on top of scheduling, and it shows up as worse adherence and worse subjective experience, independent of the general population data.
- Bolting the new wake time onto an unchanged bedtime. Covered in more detail below, but worth flagging here too because it’s the single most common reason men quit morning training within a month: they add the alarm without subtracting the same time from the other end of the night, run a growing sleep deficit, and conclude morning training “doesn’t work for them” when the real problem was never the training window.
HOW TO MAKE THIS DECISION FOR YOURSELF
The simplest decision framework for training methodology: define the primary goal in one sentence. Write it down. Now ask which approach has a stronger track record for that specific goal. Not which approach is more popular, more fun, or more aligned with the gym’s culture. Which one actually produces the adaptation being chased. If the answer’s clear, follow it regardless of tribal loyalty.
Answer not clear — both approaches serve the goal reasonably well? Default to whichever gets done more consistently. Adherence beats optimization every time. The man showing up 5 days a week with a good-enough program will always outperform the one showing up 2 days a week with a perfect one. Be honest about what actually gets stuck with.
Training age factors in too. Beginners make progress with almost any structured approach, so choosing based on enjoyment and consistency makes sense early on. Intermediate and advanced trainees need more specificity, so matching methodology to goal matters more. Where someone sits in their training career should shape how heavily these factors get weighted.
A practical test worth running before committing either direction: log perceived exertion (a simple 1-10 scale) for two weeks of morning sessions and two weeks of evening sessions, same program, same loads where possible. Most men already have a gut sense of which feels better, but the log turns a vague impression into a comparable data set — and it often reveals that the “worse” session on paper is still the one that actually gets completed, which settles the argument in practice even when it doesn’t settle it in theory.
Track two additional numbers alongside perceived exertion if the goal is genuinely data-driven: total sessions completed versus sessions planned (the adherence number) and working weight or reps on a couple of benchmark lifts (the performance number). Four weeks of both, in each window, gives a side-by-side comparison that removes most of the guesswork — and for a large share of men, the adherence number ends up mattering more to the final decision than the performance number does, even though the performance number is the one that gets debated online.
THE LONG GAME: WHAT MATTERS AT YEAR 5 AND BEYOND
Most training debates focus on short-term results — which approach produces faster gains in the first 12 weeks. That framing misses the point entirely. The training approach that actually matters is the one still being done at year 5, year 10, and beyond. Short-term optimization with long-term burnout produces nothing. Sustainable progress, even slower at first, compounds into results no 12-week program can touch.
Both Morning and Evening Exercise can serve someone long-term with intelligent implementation. The key is periodization — systematically varying training emphasis over weeks and months to prevent staleness, manage fatigue, and keep stimulating adaptation. No single approach works optimally forever. The men who make the best long-term progress are the ones who know when to push, when to back off, and when to shift emphasis.
Injury prevention matters more with age. The training approach that keeps a body healthy and consistent will always outperform one that produces faster results but creates chronic joint issues, tendon problems, or recurring tweaks. Past 35, recovery capacity drops and accumulated wear becomes a real factor. Factor durability into the decision. Not just performance.
Finally — what’s actually enjoyable matters. Training should be something looked forward to, not endured. Dread the workouts, and adherence eventually collapses no matter how optimal the programming is. Find the version of Morning or Evening Exercise that’s genuinely enjoyable, and the most important variable in training success gets solved on its own: showing up, consistently, for years.
FAQ
Is it true morning workouts boost testosterone more? Testosterone follows its own circadian rhythm and is naturally highest in the early morning regardless of whether someone trains — that’s a baseline hormonal pattern, not a training effect. Training itself produces an acute testosterone response at any time of day; the morning “boost” claim conflates the natural circadian peak with an exercise-induced one. The practical hypertrophy data (Küüsmaa 2016) actually favors evening training despite morning’s higher baseline testosterone, which tells you the hormonal timing argument is weaker than it sounds.
Does fasted morning cardio burn more fat than fed training? It shifts more of the fuel mix toward fat during the session itself (Van Proeyen 2010), but total fat loss over weeks tracks total calorie balance more than the fasted/fed state of any single session. Useful for metabolic flexibility training. Not a shortcut around calorie math.
How close to bedtime is actually too close to train? The Stutz 2019 systematic review found the real inflection point closer to 60-90 minutes before bed for vigorous training, not the often-repeated 3-hour rule. Moderate sessions finishing an hour before bed showed minimal disruption in the pooled data.
Can someone train their body to perform better in the morning? To a meaningful degree, yes. The Facer-Childs and Brandstaetter 2015 research found habitual morning training narrows the natural morning-evening performance gap over time, meaning consistency at a given time partially retrains the body’s expressed performance rhythm — it doesn’t erase the underlying circadian biology, but it blunts its practical effect.
Should someone with high blood pressure avoid morning training? Not avoid it outright, but it’s worth a conversation with a physician about medication timing and intensity if hypertension or other cardiovascular risk factors are present. The Thosar 2015 endothelial-function data and the broader cardiology literature on morning cardiac events are reasons for a more conservative approach in that population specifically — easier warm-ups, moderate rather than maximal intensity — not a blanket prohibition for otherwise healthy men.
Does caffeine change the morning-versus-evening calculation? Somewhat. A moderate dose of caffeine (roughly 3-6 mg per kg bodyweight) taken 30-60 minutes before a morning session measurably closes some of the power and alertness gap versus an afternoon session, according to several performance studies reviewed in sports science literature. It doesn’t fully equalize the two windows, but it’s the single most effective legal tool for narrowing the morning disadvantage for someone who has no flexibility to train later in the day.
Is it worth switching windows mid-program to test which works better? Only with a long enough trial on each side — four weeks minimum per window, ideally with the same program and comparable sleep — and with honest tracking of both performance and adherence, not just how a session felt on any single day. A one-week trial in each direction produces noise, not a real answer, given how much day-to-day variation exists in sleep, stress, and nutrition regardless of training time.
THE BOTTOM LINE: YOUR GOALS DETERMINE THE RIGHT CHOICE
The best time to train is whenever training actually happens, consistently, over years. Start with the time that fits your life. Then, once the habit is iron-clad, optimize timing for the goal.
Match the approach to the primary goal and give it an honest 12-week trial. Goal is specific — strength, hypertrophy, endurance — choose the methodology optimized for that adaptation. Goal is general fitness and longevity — whatever’s enjoyable and sustainable wins by default. And don’t overlook the hybrid option: plenty of experienced trainees use both approaches in different training phases, or even within the same week, pulling the best of each.
References
Editorial StandardsCorrectionsMedical DisclaimerAbout Our ContentAffiliate DisclosureSite Map