Fuelling running vs strength training

With the closure of gyms, many of us have taken our training outdoors to the running tracks. If you are like me and was in the middle of a strength block when COVID hit, then there are some things you should know about fuelling your strength sessions vs your running sessions.


First to explain some of the background physiology...


There are different forms of resistance training that are categorised based on the adaptation you're looking for - endurance, hypertrophy, strength or power.


Endurance - Think pilates... you're holding positions for a longer time or high reps but a lower weight. This is great for stability and targeting some of the supporting muscles.




Hypertrophy - Think body builders... you're increasing the size of your muscle cells. This has a high protein and energy demand as your body heals and grows your muscle tissue.


Strength - Think athletes... You're training your body to activate/recruit more muscle fibres to create a greater contractile force and lift heavier things. This type of training doesn't put your body through much metabolic damage and therefore, nutritional requirements are low compared to hypertrophy training.


Power - Think jumpers... you're recruiting muscle fibres as fast as you can to exert a high force in a short amount of time. You'll usually have a lot of rest between sets and be lifting some pretty heavy stuff.


Today I'm primarily comparing strength training with running as most athletes tend to be in some form of a strength block during the season.


1. Running will most likely burn more calories.

Of course it depends on the specifics of your training, but in general, strength training doesn't actually burn that may calories at all where as running does. Strength training causes more stress to your nervous system (nerves and brain) rather than the muscles. This kind of stress doesn't require much energy. On the other hand, running requires large amounts of energy to fuel the repetitive muscle movements.


2. After burn

If you are doing an interval or MAS style running session, you will burn through more calories after the session than if you were just going for a steady 5km or your standard strength session. Be aware, that although your session may be shorter, you may require more fuelling through the day than usual.


3. Carbohydrates

Most of us will be chewing through much more carbs in our runs than we were in strength sessions. If you've taken to a running program, you will likely need to be including more low Glycemic Index (GI) carbs in your base diet than you were previously. At low intensities and at rest, your body is predominantly burning fats as a fuel source. Fats are difficult and slow for the body to digest so it uses these when it has time. As soon as intensity increases and your muscles need fuel fast, using fats as a fuel source is too inefficient so your body turns to carbs. Therefore, if you are getting you're heart rate up in a run, your body will be burning through significant carbohydrates to power each muscle contraction that spurs you forward. If you're runs are lasting less than an hour, I would just focus on including carbs at each meal and snack so that you have plenty stored up. If you go for more intense or longer runs, fuel up with some additional carbs before hand or take a gel with you. For specific advice send me a message!


4. Protein needs will vary

There's no easy way to compare your protein targets from strength training to running. As mentioned, a pure strength session (aiming to get stronger, not bigger), doesn't place that much stress on your muscles themselves, therefore, protein needs aren't excessive. On the other hand, if you are new to running, you may actually have fairly high protein needs as the new activity places new demands on the body. However, if you're a seasoned runner, your protein requirements will be lower.


My advice regarding protein would be to include moderate amounts in each meal and snack. For example eggs or yoghurt at breakfast, milky coffee and muesli bar at morning tea, chicken at lunch and some form of meat at dinner. If you are including more plant-based options, make sure you include a wide variety of protein sources in your diet rather than just chickpeas or just grains etc.


5. Iron

Iron is essential for transporting oxygen to your working muscles. Without it you can feel early fatigue and a build up of lactic acid during an easy run. Women are at greater risk of iron deficiency than men due to menstrual cycles. However, in addition to this, runners have found to be at increased risk again, due to the foot strike (damages red blood cells) and increased loses through sweat.


Animal forms of iron (red meat) is readily absorbed by your body. Plant forms (legumes, tofu, chia, cashew nuts, dark leafy greens etc) are poorly absorbed. If you are relying heavily on plant sources of iron make sure to pair you iron with a source of vitamin C (eg orange or lemon juice) as vitamin C helps absorption but steer clear of calcium (dairy) and teas and coffees 2 hours either side of an iron-rich meal as these can inhibit/compete with iron absorption.


6. Electrolytes and hydration

I'm fairly sure that I'm not alone in sweating a whole lot more on my runs outdoors than in my strength session in an air-conditioned gym. You're most likely going to be losing a whole lot more fluid and salts.


The general fluid guidelines are 30-35mL of water/fluid per kg of your body weight each day. To this answer I then add on some extra for activity. There's no perfect way to test how much water you need before or after your run but one way you can estimate it is to take a weight before your go for your run (minimal clothing) and then a weight after your run (minimal clothing). For every kg that you've lost, replace this with an additional 1-1.5L of water.


Electrolytes are a cluster of different minerals that are essential for electrical signalling in your body. If you're sweating a whole lot more than you did at the gym, you may be losing significantly more of these salts. The Australian diet is typically high in salts so unless you are training for hours in the sun, it isn't likely that you'll need to throw down a salt sachet just yet. I love the idea of a fruit smoothie after a run as a mixture of dairy and fruits such as bananas contain a good balance of electrolytes whilst refuelling with water, carbs and protein.

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