Whether you’re running to keep fit, training for a marathon or just looking to lose some weight, exercise and running changes our bodies. When you begin exercising regularly, your body undergoes several physiological and neuromuscular changes, and the changes will vary according to the frequency duration and intensity of your training program.

It’s important to note that these changes take time (usually four to eight weeks) and all beneficial adaptations will disappear when you stop training.

Training also causes major changes in your muscles. During exercise, muscle oxygen consumption increases up to 70 times above resting values. This enables more oxygen, nutrients and hormones to be delivered to the muscles, and allowing for better removal of heat. Aerobic (endurance) training also increases the muscles’ ability to use oxygen to produce movement and improves their ability to store glycogen.

The kind of training you do affects the changes in your muscle fibres. Our body has two different types of muscle fibres: fast-twitch for anaerobic or sprint-type activity and slow-twitch for endurance activity. Training for speed and power develops and maximises the fast-twitch fibres, while training for endurance develops and maximises the slow-twitch fibres.

Like muscle tissue, bones also respond to exercise stimulus. The bones become stressed during exercise due to the tendons and muscles that pull on the bone. This added strain on the bones stimulates the bones to become denser. However, it is common in runners to experience stress fractures due to the repetitive nature and impact of running movement.

Micro muscular tears and bleeding is very common in runners. This is a natural process of exercise. However, if you do not have healthy and varied diet, this can lead to nutrient deficiencies, such as iron deficiency, and further injury.

As we run our bodies call on adenosine triphosphate (ATP) as a source of energy, but our bodies can only store a small amount of both ATP and glucose, so as we run our body starts to create extra supplies. As a result, our bodies demand for more energy/fuel increases, and in turn, so too does our hunger. This is because we burn more calories when we exercise and the higher the intensity or the longer the duration of the run, the more calories our body will burn.

How should you prepare for a running event in the weeks leading up to it?

The most important thing to recognise is that as your training (running) distance increases, so do your calorie needs, especially calories from carbohydrates. Depending on the frequency and intensity of the training, and the distance covered, runners require approximately 5-10 grams of carbohydrate per kilogram of body weight during training and closer to the upper end of this range before long runs. The reason for the requirement of high amounts of carbohydrates is to saturate the muscles with glycogen, the storage form of carbohydrate that fuels endurance exercise. The regular training diet should be at least 55% carbohydrate during daily training and 55% to 65% before an endurance event or long training run.

A common theme with long distance runners is that their immune system becomes suppressed and are more vulnerable to colds and flu’s. This is because running (and exercise in general) produces free radicals due to the extra intake of oxygen required by the body. While the body’s cells can protect against some free radical damage, they can only do so much. Therefore, runners should increase their antioxidant intake during the running season. Antioxidants from food (mainly fruit and vegetables) or supplements help provide the rest of the natural defense.

The more frequent your training in addition to the longer distances, the more likely your body will experience inflammation, due to the repetitive nature of running and damage to your musculoskeletal system. Therefore, runners should try to increase their consumption of oily fish such as salmon, tuna, mackerel, sardines, swordfish and anchovies due to the inflammation-fighting properties of omega-3 fatty acids, which help alleviate muscle soreness and boost immunity. An alternative is to consume a high quality fish oil supplement.

Hydration is one of the most important components of a runner’s diet. Staying well hydrated is going to help your body’s performance as well as reduce your risk of muscle cramping during and after your run or competition. As we sweat, our body loses important electrolytes such as sodium, potassium, calcium and magnesium. If you are prone to sweating heavily then your body may lose greater amounts of electrolytes. Adding electrolytes to your water or consuming a beverage with added electrolytes may be beneficial when you are on your longer runs (i.e. greater than 60 minutes). If you are starting out as a runner, you may be more prone to muscle cramps. A magnesium supplement may assist but it is important to get advice from a sports dietitian or nutritionist to understand your body’s needs.

How should you fuel your body before a run?

The food or fluids you eat and drink before training or a running event should aim to:

  • Fuel and hydrate your body for the exercise session ahead
  • Get the most out of your training session – sustain quality and intensity for longer
  • Avoid gut upset or unwanted toilet breaks
  • Help you achieve your body composition goals
  • Avoid unwelcome and distracting hunger pangs during the session

The time of an event or when you choose to do your training runs will dictate how much you eat and at what time. Most races/events are conducted in the morning, so it doesn’t make sense to sacrifice sleep in order to eat and digest a full meal, which would usually take two to four hours. However, you should aim to eat a light carbohydrate-based snack one to two hours before competing (or training, if you train early in the morning) to top up the body’s glycogen stores. Opting for low fibre meals/snacks is smart to help prevent stomach upset or discomfort. Easy to digest options include toast or crumpets with jam or honey, a protein shake, small bowl of cereal or yoghurt and fruit.  For runners that suffer from nerves/butterflies before a race, they may find a liquid meal supplement such as a home-made smoothie, or sports drinks, gels and bars, a better option.

It is important to practice how it feels to run long distances after eating various pre-race meals, and choose the one that works best for you. If you find this challenging to figure out by yourself, a sports dietitian can help you formulate the best training plan

How should you re-fuel after a long run?

When it comes to choosing the best post-workout snack or meal, there is no one “best” option or “one size (option) fits all” approach and recovery strategies should be individualised based on workload, body size, duration of the training just completed, goals related to body composition and personal preferences.

The main goals that all recovery snacks or meals should have in mind, include:

  • Appropriate refuel glycogen stores and rehydrate the body
  • Promote muscle repair and growth
  • Optimise adaptation from the training session
  • Support the immune system

The focus should be on the composition of the snack or meal when it comes to macronutrients (protein, carbohydrates and fats), fluid and electrolytes. A general rule of thumb according to the latest sports nutrition guidelines when it comes to carbohydrate intake post-exercise, is to consume 1.2g/kg of body mass per hour for the first four hours (e.g. 85g carbohydrate for a 70kg person). The greatest benefits are seen when paired with protein and consumed within 30-45 minutes after completing your run. This immediate delivery not only helps with the replenishment of glycogen stores in the muscle but may also have a positive effect on the immune system as it helps down-regulate the hormonal stress response.

When it comes to protein requirements, consuming essential amino acids, in particular leucine, in the immediate recovery period is essential for promotion of muscle protein synthesis, critical for muscle recovery and adaptation. The general recommendation is to consume 20-30g of protein (or an equivalent of 9g of essential amino acids if you’re supplementing), which has been reported to maximise muscle protein synthesis in the first hour of post-exercise recovery.

Additional running and diet tips

Rest and recovery is absolutely vital to allow your body to repair from the micro muscular damage that occurs during training and competition. By allowing some rest days, especially if you are a beginner, will reduce your risk of injury and allow you to perform optimally during your training sessions. Make sure you have plenty of quality sleep. Aim for at least seven to eight hours a night.

During the tapering period leading up to an event, it is important for runners to reduce their caloric intake for each kilometre removed from training. It is normal to expect some weight gain with a taper due to the increase in glycogen content. However, many runners experience extreme hunger during this time and some gain too much extra weight because they do not adjust their diet accordingly. This weight gain can have a negative impact on your performance.

No matter what level of competition you are at, if you are someone looking to improve your training and competition performance, you may consider seeing a sports dietitian who specialises in nutrition and performance who can put together a personalised training and competition plan to get you feeling and training your best.