Athletes competing in power sports such as sprinting need to pay close attention to their body composition. There is an undeniable correlation between optimal body fat percentages (BF%) and improved performance. Whilst training during the off season should be focused on building muscle and increasing power, it is a different story as the off season ends. In the weeks before competition the athlete should be focused on cutting body fat and unneeded muscle mass to further enhance their power to weight ratio. This is important as unneeded mass acts as a deadweight reducing performance. Low body fat is also an important strategy to reduce injury risk.
Ideal body fat % for sprinters
These ranges are only a guide and baseline measures should predominately be used as a starting point to compare to, rather than aiming for a particular BF%. Ideal BF% will vary between individuals so aiming for the targets above isn’t always what’s best for the individual athlete.
How to Measure Body Fat %
The two most common ways to measure BF% are DXA and skinfolds. These two measures can produce vastly different results. Therefore periodically measuring BF% using the same tools will present a reliable association between BF% and performance.
- Most accurate way of measuring body composition
- DXA is a high tech scanning machine that gives accurate levels of total body fat, lean body mass, and bone density mass
- Usually used when athletes don’t have access to DXA due to it’s numerous flaws Skinfold Flaws
- Different results will be achieved if using different equations.
- If a different piece of skin is used when re-measuring the skinfold, results will not be accurate
- Incorrect technique when using callipers is common
- The results are heavily influenced by how accurately skinfold sites are located
- Calliper equations also make assumptions about body fat distributions e.g. the amount of subcutaneous fat in most people is used
- Measured using callipers to determine skinfold thickness at certain points on the body
1. Dual-energy X-ray absorptiometry (DXA)
2. Skinfold Measurements
Manipulating Body Fat %
When the athlete has their BF% and total energy expenditure they can begin tailoring their nutritional plan to achieve a daily energy deficit. Athletes should always take care not to aim for drastic, short term drops in body fat. Instead it should be a gradual process that does not impair the athletes day to day life.
- 32.2MJ or 7700 calories of energy deficit leads to 1 kg of body mass lost which is mostly fat, if consuming a balanced diet. (e.g. over 1 week) In the context of actual foodsTo put it into context of actual foods:
- 1 cup of cashews= 2929kJ or 700 calories
- 1 piece of fruit pie= 1674kJ or 400 calories
- 1 apple= 523kJ or 125 calories
- Chicken and noodles (1 cup)= 1046kJ or 350 calories
How to create an energy deficit?
Manipulating body fat levels requires specialized training and a well thought out dietary plan. Goals should include:
- Reduce excess kJ or calories in the diet, particularly excess fat (especially trans fats) found in food like cakes, biscuits and sweets. Why is it bad?Studies with animals have shown that consuming the equivalent in calories of trans fats leads to more weight gain than healthy fats of the same caloric value.
- Eating balanced meals spread throughout the day
- Consuming complex carbohydrates like whole grains, vegetables and dairy Why so complicated?Complex carbohydrates are an essential form of energy for sprinters aiming to lose body fat. While simple carbohydrates are quick to digest and cause blood-sugar spikes, complex carbs need to be broken down and therefore take longer to digest. This longer digestion causes a longer lasting full feeling and blood-sugar spikes are less intense meaning you have steady energy levels throughout the day.
- Sprint specific resistance exercise to burn fat and build muscle beneficial to sprinting
Easily track your food intake to see if you are achieving an energy deficit through My Fitness Pal. Through the app or website you can search and enter foods. The app is free and also has a barcode scanning function for faster input.