Swimming Calories for Women Over 40 — What Actually Drives Burn

Exercise is undoubtedly a great way to burn calories and manage weight. However, it isn’t the biggest contributor to energy expenditure.

Studies show that energy expenditure is divided into three categories: Resting metabolic rate (RMR), thermic effect of food (TEF), and activity energy expenditure (NEAT/physical activity).

Here is a brief description of each and the percentage of energy they burn:

• Resting Metabolic Rate (RMR): Calories the body burns at rest while sustaining basic function. This accounts for 60–80% of total energy expenditure.

• Thermic Effect of Food (TEF): Energy expended to digest and absorb food. This accounts for 10% of total energy expenditure.

• Physical Activity: This includes exercise and non-exercise physical activity (NEAT), such as walking and performing daily tasks. These account for 20–50% of energy expenditure.

As we can see, while exercise does contribute to energy expenditure, resting metabolic rate consumes the most energy. Therefore, if your calorie intake is below this number (calorie deficit), you will be burning fat at rest.

That being said, swimming is an incredible form of exercise that should not be overlooked for cardiovascular fitness, weight management, and overall health.

Driven by factors such as intensity, water temperature, buoyancy, efficiency, and stroke variety, it is one of the most metabolically complex forms of cardio.

Below is a brief description of each and how they affect calorie burn:

• Intensity: The biggest driving factor, intervals, and threshold sets spike VO2 and excess post-exercise oxygen consumption.

• Water Temperature: Colder pools, which are equal to or less than 26 °C, increase thermogenic cost as the body is required to maintain core temperature.

• Buoyancy & Efficiency: Skilled swimmers displace less water each stroke. This means they burn fewer calories. Meanwhile, beginners burn more due to displacing more water, resulting in drag, meaning more calories burned.

• Stroke Variety: Alternating strokes or using fins can involve more muscle groups, increasing calories burned.

Swimming Calorie Calculator — Inputs and Outputs You’ll Use

The swimming calorie calculator for women requires different inputs, including weight, distance, time, pace, stroke type, and more, to determine the number of calories burned each session. Below, we discuss each input and how it influences your results.

Inputs

• Unit: Choose between metric and imperial
• Weight: Body weight influences energy expenditure.
• Distance or Time: Longer distances and durations expend more calories.
• Average Pace/Split: The faster your pace, the greater the calorie burn.
• Stroke Type: Different strokes require different muscles, altering energy expenditure.
• Pool Length (25m/25y/50m): Shorter pools increase calorie burn as wall push-offs are more frequent. Longer pools have fewer turns, meaning smoother movement and lower energy cost.
• Environment (Pool vs Open-Water) (optional): Waves and currents provide greater resistance, leading to an unpredictable pace (10–20% higher energy cost than pool swimming).
• Water Temperature (optional): Cold water results in a minor thermogenic boost to maintain core temperature. Warm water results in a lower calorie burn, but leads to a higher perception of exertion due to heat stress.

Outputs

• Total Calories: The total amount of calories burned for the session.
• Kcal/Min: Number of calories burned each minute.
• Pace ↔ Speed Equivalence: The speed (km/h) you are traveling and how speed it takes to complete each km (pace), e.g., 6.0 km/h = 10.00 min/km
• Suggested Fueling Window: The ideal time to each or drink before and after, to optimize performance.

How the Calculator Estimates Calories — METs for Stroke and Intensity

The swimming calorie calculator uses the MET method (metabolic equivalent of task) to estimate calories.

Each stroke has a different oxygen cost as it requires different body positions, drag, and muscle engagement. Below, we explain the formulas used in the swimming calorie calculator.

Choosing MET

Choosing the correct MET should reflect the stroke style and level of effort. For example, free style is the most efficient, requiring less energy, resulting in a lower MET. Meanwhile, strokes such as breaststroke and butterfly have a greater muscle demand, resulting in higher MET.

Below is a list of the types of strokes, their metabolic equivalent of task (MET), and approximate calories per minute for 60 kg, 70 kg, and 80 kg.

MET Method (Simple)

The MET method is a simple way to calculate calories burned. To do this, you multiply your weight by the MET value that corresponds to your stroke type listed above.

Example

• MET × Weight(kg) × Duration(hours) = Calories

Let’s use the example of a 75 kg woman, performing moderate freestyle (MET = 8.0), for 30 minutes:

• 8.0 (MET) x 75 (kg) x 0.5 (hours) = 300 kcal burned

kcal/min Conversion (Display in “advanced”)

The following formula offers a more advanced breakdown, determining kcal/min.

• (MET × 3.5 × weight(kg)) ÷ 200 = kcal/min

In this example, we will use a 65 kg woman, performing moderate breaststroke (10.0):

• (10.0 x 3.5 x 65 kg) ÷ 200 = 11.4 kcal/min

Use Your Number — Fueling, Fat Loss, and Recovery in Midlife

Once you have received your results, they can now be applied to your needs. Below, we discuss how to apply the results for fat loss, performance, and menopause-specific training.

Fat Loss

Swimming for fat loss, like all forms of exercise, is centered around a calorie deficit, which is consuming fewer calories than your RMR. For example, if your RMR is 1,700 kcal/day, you will need to apply a deficit of 200–300 kcal/day. This will allow you to burn fat at rest.

Combined with the energy expenditure from your swimming will place you in a greater deficit.

Example

• 1,700 kcal - 200 kcal (deficit) - 225 kcal (calories burned) = 1,275 kcal

Combined, your energy expenditure and deficit will create a 424 kcal deficit. While this is excellent for weight loss, ensure your deficit isn’t too low, as a large deficit can be unsustainable, impacting energy levels and recovery.

To ensure your calorie intake is sufficient, we recommend calculating an estimated calories burned using the MET method and allowing this to be your deficit on your swimming days.

Meanwhile, on your off-days, you can apply a calorie deficit through nutrition. If, after a few sessions, you feel your energy levels are stable, you can apply a 100–200 kcal deficit through nutrition to increase fat burn.

Calorie and Macronutrient Recommendations

• Rest Day Calories: Calorie deficit (-200–300 kcal/day from nutrition)
• Swimming Day Calories: Calorie deficit (-200–300 kcal/day from swimming)
• Carbohydrates: 35–45% of daily calorie intake
• Protein: 30–35% of daily calorie intake
• Fats: 25–30% of daily calorie intake

Tips

• Aim for consistency and avoid major deficits. This will make your routine more sustainable, leading to better long-term results.
• Start with smaller deficits. This will help you ease into your calorie deficit and allow you to lower your calories when fat loss plateaus.

Performance

The swimming calorie calculator provides valuable insights that can help you improve performance. Improving the pool requires a greater emphasis on carbohydrate intake to not only fuel training, but also to restore muscle energy stores known as glycogen.

Meanwhile, a balance of protein (1.6–2.2 g/kg) and healthy fats is required to repair muscle, reduce inflammation, and absorb vital nutrients.

Hydration is vital in an aquatic environment. Research shows that a 2.5% of body weight is lost during high-intensity aquatic training can result in dehydration. This can lead to poor performance.

Electrolytes post-swimming are shown to restore fluid balance and support muscle and nerve function to support performance.

Calorie and Macronutrient Recommendations

• Calories: Balanced (equal to RMR)
• Carbohydrates: 55–60% of daily calorie intake
• Protein: 20–25% of daily calorie intake
• Fats: 20 –25% of daily calorie intake

Menopause-specific

Studies show that the decline of estrogen levels in midlife can lead to physiological changes, including loss of muscle mass, strength. Additional sources highlight reduced lower-body blood flow and oxygen-carrying capacity.

During menopause, these areas require additional focus to improve swimming performance and overall health. This can be done with the following steps:

• Resistance Training: Train 2–3 times a week to maintain lean body mass and improve strength. Sources indicate that this can also improve performance.

• Monitor Iron Levels: Iron levels can increase as estrogen decreases. Studies indicate that this can lead to iron overload, resulting in oxidative stress, which can damage muscle, tissue, and performance. Speak to your doctor about iron level testing.

• Gradually Increase Volume: Start slow with 1–2 swimming sessions per week at shorter durations and gradually increase the duration or number of sessions. Increase and decrease based on your energy levels as needed.

• Shoulder Care: Perform a warm-up routine and shoulder strengthening exercises that target the rotator cuff during your resistance training sessions to preserve shoulder strength and mobility.

Nutritionally, the focus should be on carbohydrates, protein, healthy fats, and electrolytes. This will help fuel sessions, support recovery, and restore fluid balance.

Calorie and Macronutrient Recommendations

• Calories: Balanced (equal to RMR)
• Carbohydrates: 40–45% of daily calorie intake
• Protein: 25–30% of daily calorie intake
• Fats: 25–30% of daily calorie intake

Worked Examples (Follow Along)

Now that we have highlighted the different formulas, we will share examples for different goals, including easy freestyle, mixed sets, and open water.

Easy 30-min Freestyle (25m pool, steady pace)

The following example is a 70 kg woman performing freestyle for 30 seconds.

Key Information

• Weight: 70 kg
• Duration: 30 minutes (0.5 hours)
• MET: 8.0 (moderate/steady)
• Stroke: Freestyle
• Environment: Pool

Step 1: MET Method

Formula: MET × Weight(kg) × Duration(hours) = Calories

• 8.0 x 70 (kg) x 0.5 (hours) = 280 kcal

Step 2: kcal/min conversion

Formula: (MET × 3.5 × weight(kg)) ÷ 200 = kcal/min

• (8.0 x 3.5 x 70 kg) ÷ 200 = 9.8 kcal/min

Mixed Set 1,500 m with Drills and Pull Buoy

This next example is a 1500m, 30-minute duration, 70 kg, with a mixture of strokes and drilling with a pull buoy (upper body only, reduced leg drive.

Key Information

• Weight: 70 kg
• Duration: 30 minutes
• MET
  • Freestyle (moderate): 8.0
  • Breaststroke (moderate): 10
  • Drills: 6.0
• Stroke:
  • Freestyle (50%)
  • Breaststroke (30%)
  • Drills (20%)
• Environment: Pool

Step 1: Determine average MET

Formula: (Stroke % x MET) + (Stroke % x MET) = MET average

• (0.5 x 8.0) + (0.3 x 10.0) + (0.2 x 6.0) =
• 4 + 3 + 1.2 = 8.2 METs

Step 2: MET Method

Formula: (MET x 3.5 x weight (kg)) ÷ 200 = kcal/min

• (8.2 x 3.5 x 70 kg) ÷ 200 = 10.0 kcal/min

Step 3: Estimate total calories burned

Formula: kcal/min x min = kcals burned

• 10.0 kcal/min x 30 min = 300 kcal burned

Open-water 45-min Swim (Cool Water, Light Chop)

The next example is a 65 kg woman, swimming freestyle in open water for 45 minutes.

Key Information

• Weight: 65 kg
• Duration: 45 minutes
• Stroke: Freestyle
• MET: 8.0
• Environment: Added to MET
  • Cool: +10–20% (more drag, wave work)
  • Open-water: +3–5% (thermoregulation)
• MET + Environmental Factors (20%): 9.6

Step 1: MET Method

• (9.6 x 3.5 x 65) ÷ 200 = 10.9 kcal/min

Step 2: Estimate total calories burned

• 10.9 x 45 min = 490.5 kcal/min

Accuracy and Re-Testing

Swimming is a complex which means you must be aware of the subtle changes to maintain accuracy. During programming, you need to continue tracking factors such as weight, stroke intensity, and duration.

Expect ±10–20% Variance

It is important to expect a ±10–20% variance between calculator results and your energy expenditure, as swimming has many variables that can impact the results.

While calculating using MET for different strokes, duration, and weight, this doesn’t take into account poor technique, fatigue, and daily energy levels, which can alter performance.

For example, if you are estimated to burn 200 kcal, a ±20% variance would be 160–240 kcal. Many people overestimate their expenditure, which can make things confusing when they don’t see results.

Expecting a variance and using it to underestimate ensures that you are within your daily calorie allowance.

Keep Method Consistent

Keeping your calculations consistent is vital for ensuring accuracy. Below, we highlight areas that can help you minimize the margin for error.

• Use the same equations, units, and calculations.
• Use the same (correct) MET figures.
• Check in and update monthly.
• Avoid mixing data from different tracking devices.
• Record active swim time only. Tracking swimming and rest intervals.
• Always record poor environment (pool length, water temp, indoor, open-water, chop)

Re-check if Pace, Stroke Mix, or Weight Changes

Re-checking pace, stroke mix, and weight changes is vital for accuracy. Energy levels can impact performance. This can turn your intended vigorous freestyle session into a moderate freestyle session, affecting your calculations. Meanwhile, changes to stroke and weight can alter calculations.

Because some of these variables are subject to change regularly, it is important to re-check to ensure your calculations are correct.

Sources

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4. Collins BC, Laakkonen EK, Lowe DA. Aging of the musculoskeletal system: How the loss of estrogen impacts muscle strength. Bone. 2019 Jun;123:137-144. doi: 10.1016/j.bone.2019.03.033. Epub 2019 Mar 28. PMID: 30930293; PMCID: PMC6491229. https://pmc.ncbi.nlm.nih.gov/articles/PMC6491229/
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