Why Does Swimming Make You Tired – 15 Reasons and Fixing Tips

Why Does Swimming Make You Tired - 15 Reasons and Fixing Tips

It’s common to feel wiped out and fatigued after a swimming session, even if you’re in great shape. Unlike other exercise, swimming seems to zap energy levels disproportionately. If you find yourself exhausted after hours in the pool, there are a few reasons why swimming taxes the body more than other sports.

Is This Normal?

Absolutely! Feeling tired after swimming is extremely normal. The unique cardiovascular and muscular demands of swimming make fatigue an expected response. However, chronic extreme exhaustion after laps may indicate issues like poor nutrition, dehydration, or overtraining.

Why Does Swimming Make You Tired?

What exactly makes swimming so tiring at times? Here are the primary factors:

Cause Explanation Effect
Full body workout Nearly all major muscles engaged Widespread fatigue
Cardiovascular exercise Strain on heart and lungs Tired cardiorespiratory system
Anaerobic AND aerobic Use of all energy systems Zapped energy reserves
Resistance from water Working against water resistance Muscle fiber exhaustion
Heat loss Rapid loss of body heat Hypothermia and shivering
Vasoconstriction Constricted blood vessels and circulation Impaired oxygen/nutrient delivery
Hyperventilation Excessive breathing Respiratory muscle fatigue
Dehydration Fluid loss thickens blood, reduces plasma Heart must work harder
Horizontal body position Unnatural prone position Core/back exertion to stay afloat
Rotational movements Unfamiliar twisting and rotating Effortful on back and ab muscles
Fighting buoyancy Resisting upper body buoyancy Expending energy to stay balanced
Surfactant damage Impaired lung surfactant Greater infection risk
Latent virus reactivation Immune suppression from exertion Body works hard to keep latent viruses in check
Leukocyte damage Free radicals destroy white blood cells Decline in immune defenses

The Physical Demands of Swimming

The Physical Demands of Swimming

Swimming necessitates extensive physical exertion, which can certainly take a toll and zap your energy.

1. Full Body Workout

When you swim, nearly all of your major muscle groups are engaged, including:

  • Arms and shoulders to propel you through the water
  • Back and core to maintain proper form
  • Legs for kicking
  • Chest, shoulders and triceps to support the body position

Utilizing most of your musculature demands great effort and leaves many muscle groups fatigued. This overall workout stress across the entire body overwhelms your system.

2. Cardiovascular Exercise

Swimming requires considerable cardiorespiratory endurance to regularly pump your arms and legs while controlling your breathing rhythm.

The heart and lungs are put under significant strain during swimming. This intense cardiovascular workout tires out these critical organ systems.

3. Anaerobic AND Aerobic

Swimming uses both anaerobic (sprinting) and aerobic (distance) energy systems across changing intensities.

The combo anaerobic-aerobic workout taps into all your energy reserves, which accumulates high levels of fatigue.

4. Resistance Training

The water itself provides resistance on all your swimming movements, turning the pool into a giant resistance training machine.

This constant battle against resistance wears out your muscle fibers as you work against the water with each stroke.

The Thermoregulatory Challenges

The Thermoregulatory Challenges

Regulating body temperature during swimming also expends considerable energy that increases fatigue:

5. Heat Loss

Water conducts heat away from your body approximately 25 times faster than air. This rapid heat loss can lower core body temperature, causing you to feel tired as your body tries to warm back up.

6. Shivering

Your body responds to hypothermia through shivering and muscle contractions to generate warmth. But these involuntary movements also tire out your musculature.

7. Vasoconstriction

To reduce heat loss, blood vessels in the skin constrict to divert blood to the core and vital organs when swimming. This impaired circulation contributes to exhaustion.

8. Hyperventilation

Swimmers often hyperventilate and overbreathe due to anxiety about swimming and trying to optimize oxygen. But this excess respiration and tighter breathing tire out the respiratory muscles.

9. The Role of Dehydration

Maintaining hydration while swimming is crucial, but often overlooked. Dehydration leads to:

  • Thickened blood – Less plasma volume makes the heart work harder to pump blood.
  • Reduced blood flow – Less overall fluid lowers blood circulation.
  • Impaired oxygen delivery – Dehydration reduces oxygen transported in the blood.

Together, these effects of dehydration significantly drain your energy as your body struggles to function with inadequate blood flow and oxygen delivery to muscles.

Energy Expenditure For Flotation

Energy Expenditure For Flotation

Staying afloat and maintaining proper positioning in the water also requires substantial energy expenditure:

10. Horizontal Body Position

The prone horizontal body position used in most swimming strokes is unnatural and gravity-fighting. Your core and back work extensively to keep your lower body from sinking.

11. Unaccustomed Rotational Movements

Rotating and twisting the torso involved in strokes like the butterfly, backstroke and freestyle demands focused effort from the abs and back muscles to execute these unfamiliar rotational movements.

12. Fighting Buoyancy

Particularly for fit swimmers with greater muscle mass, extra energy must be expended to resist upper body buoyancy and keep the lower body from rising to the surface.

Immune System Alterations

Immune System Alterations

Extensive swimming can also impact your immune function, leading to increased fatigue:

13. Surfactant Damage

The air-water interface repeatedly damages pulmonary surfactant during breathing. Surfactant normally prevents lung tissue collapse. Impaired surfactant increases susceptibility to respiratory infections.

14. Chronic Latent Viruses

Latent viruses like cytomegalovirus (CMV) that establish lifelong infection can reactivate after intense swimming due to immune suppression. This taxes your system.

15. Destroyed Leukocytes

Free radical formation damages leukocytes after swimming. With reduced white blood cells, your immune defenses decline, contributing to exhaustion.

Other Factors That Can Increase Swim Fatigue

A few other variables may also play a role in swim-related tiredness:

  • High mental effort to monitor breathing rhythm and technique
  • Exposure to chemicals like chlorine and bromine
  • Earlier morning workout times linked to greater exertion
  • Insufficient calorie and carbohydrate intake to fuel intense swimming
  • Overtraining with inadequate rest between difficult swim sessions

What are some consequences that can arise from post-swim fatigue?

What are some consequences that can arise from post-swim fatigue? Here are a few:

Impaired Performance in Other Sports

Swimmers often participate in other sports and exercise modalities. But insufficient recovery from swimming can hinder strength, speed, and stamina for activities like running, weightlifting, tennis, etc. due to lingering fatigue.

Increased Risk of Injury

Overuse injuries like rotator cuff strains and knee tendinitis become more likely if swimming-related fatigue is not managed properly. Fatigued muscles and joints are vulnerable to repetitive strain injuries.

Compromised Immune Function

Chronic or excessive fatigue from swimming places strain on the body that impairs immune defenses. This can make you more prone to illness following intense training and competitions during cold winter months.

Hindered Skill Development

Fatigue impedes your ability to focus on proper stroke mechanics and efficiency. Attempting to swim while tired often leads to reverting to poor technical habits. Sub-optimal skill development may occur.

Negative Effects on Growth

In adolescent swimmers, chronic fatigue from overtraining can actually stunt growth and development. Hormones promoting growth reduce when the body is under prolonged physical stress.

Mood Changes

Physical tiredness frequently manifests as mental irritability, crankiness, and generally low motivation and morale. Fatigue-related mood disruptions can reduce enjoyment of the sport over time.

Decreased Appetite

The hunger hormone, ghrelin, decreases after intense endurance exercise while leptin increases. These hormonal changes often suppress appetite after swimming, making it hard to eat adequately for recovery.

9 Tips to Prevent Post-Swim Fatigue

If swimming fatigue is hindering your performance or training, here are some methods to help overcome it:

Refuel After Each Session

Eat a mix of carbohydrates and protein within 30-60 minutes post-swim to replenish glycogen stores and aid muscle recovery. Hydrate properly too. Nutrition is key.

Monitor Overtraining

Schedule off days and avoid excessive distance, speed, and intensity every session. Vary workouts appropriately. Listen to your body and allow proper recovery between challenging sessions.

Strengthen Upper Body and Core

Follow a structured strength program for arms, chest, shoulders, and core 2-3 times per week to support muscles under heavy use while swimming. Strengthen weaknesses.

Use Fins Strategically

Occasionally using fins during warm-up, cool-down, and select sets reduces localized muscular strain and fatigue by relying more on your lower body for propulsion.

Assess Technique and Efficiency

fixing flaws in your stroke mechanics and developing an efficient stroke reduces energy expenditure and fatigue over time. Work on form and minimizing drag.

Rule Out Medical Issues

See a sports medicine doctor to check for underlying issues like anemia, low vitamin D, hypothyroidism, or other conditions that could exacerbate swimming fatigue.

Try Compression Garments

Wearing tight-fitting swimming garments may help reduce muscle vibration and fatigue. Proper fitting and high quality compression gear provides the best results.

Adjust Training Intensity and Volume

Closely monitor rate of perceived exertion during sets. Lower volume, intensity, or frequency if ordinary workouts start becoming excessively tiring.

Optimize Sleep Habits

Ensure you get adequate, high-quality sleep to allow your body to fully recover between challenging workouts. Sleep is crucial.

Signs of Overtraining

Make sure marathon swim sessions don’t put you into an overtrained state. Watch for these signs:

  • Constant muscle soreness
  • Decline in performance
  • Increased injury risk
  • Changes in appetite and sleep
  • Irritability and mood changes
  • Lack of energy and motivation
  • Headaches or muscle cramps during workouts

If you experience these types of symptoms, cut back on swim volume and intensity and focus on active rest and recovery.

When To See A Doctor

See your physician if you experience:

  • Fatigue lasting over 2 weeks
  • Severe shortness of breath or chest pain during swim sessions
  • Fever, chills or illness after swimming
  • Swallowing pool water leading to diarrhea or vomiting

A respiratory infection, swimming-induced pulmonary edema or other medical issue could be exacerbating fatigue. Seek medical advice regarding any ongoing swimming-related exhaustion.


While some fatigue after swimming is perfectly normal, excessive and persistent tiredness can jeopardize performance goals. Look at your training load, nutrition, rest, and recovery habits if pool sessions continue leaving you drained. There are solutions. With attention to proper programming and bodily cues, swimming should invigorate you without crossing the fatigue line.

Frequently Asked Questions

How long after a swimming workout should fatigue subside?

Expect moderate tiredness for 1-2 hours post-swim. Lingering fatigue beyond 24 hours may signal overtraining or need for more rest. See a doctor if debilitating fatigue persists for days.

Will taking vitamin supplements reduce swimming fatigue?

Maybe. Vitamins C, D, and B12 support energy pathways. But get bloodwork done first to confirm a deficiency before supplementing. Mega-doses provide no benefit if levels are already optimal.

Does drinking caffeine help provide an energy boost before swimming?

A little caffeine 30-60 minutes pre-swim can enhance alertness and performance if you don’t overdo it. But avoid reliance on caffeine. Focus more on proper training, fueling and rest.

Will soaking in a cold tub after swimming help reduce fatigue?

Potentially. Cold water immersion constricts blood vessels, reducing swelling and inflammation that contribute to delayed onset muscle soreness and fatigue. But cold soaks aren’t for everyone.

Should I avoid eating 2-3 hours before swimming to prevent cramps?

No, avoid exercise fasted. Eat a carb-rich snack 1-2 hours pre-swim to fuel muscles and prevent energy crashes. Just avoid big meals right before swimming. Hydrate properly too.

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