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Fighting Fatigue

by Anna Renderer

Whether you are running to lose weight or compete in a road race, it’s important to learn how to get the most from your running workout. It can be frustrating to hit a wall halfway through your goal distance, or feel like a ton of bricks on your first lap around the track. Feeling sore and tired for a few days after a run can also be unmotivating. Some simple facts can help you learn how to help that muscle fatigue and soreness to improve your endurance and keep you going strong!

Lactate threshold, around 85% Max Heart Rate is the best predictor of your running endurance. This physiological variable will tell you your fastest sustainable aerobic speed. In other words, how long you can run without hitting that wall where your legs feel like lead and just need to stop. Trial and error can get you in the appropriate training zone but if you want to start getting results right away your lactate threshold can be measured with VO2 Metabolic Testing ( Staying within your lactate threshold will allow you to continue running for longer distances which is vital when training for a road race and important when trying to lose weight.

For runners who start a race/run off too fast (> 85% MHR), it is almost impossible to keep that same pace the entire time and you will hit a wall shortly into it. Run a Negative Split: Begin at the pace you can maintain the entire race/run and then for the second half of the race/run try to run the same pace or faster.

It is imperative to eat, drink, and rest correctly before and after running. This has the greatest effect on muscle fatigue and soreness. You’ve all heard the myth, “I’m sore because of the lactic acid in my muscles”. Lactic acid does not cause fatigue or soreness! Lactic Acid is simply a byproduct of muscle working in an anaerobic state (oxygen supply doesn’t meet the muscles oxygen demand). Soreness is causes by muscle tears and inflammation from exercise along with some important physiological changes such as dehydration, glycogen depletion, acidosis, and metabolic byproducts such as H, K, and ADP. The way you fuel and rest your body will influence many of these physiological changes. Remember: Adaptations to training occur during recovery not during training itself. After the workout your body is weaker, not stronger than it was coming in. The hours following exercise, your body adapts and physiologically overcompensates so that the same exercise intensity will not cause the same degree of muscle fatigue or soreness. In short, your fitness has improved.

Dehydration is among the most common nutritional cause of performance decline. Being hydrated will make a huge difference during your run and post recovery. It is most important to drink water when not working out because if you are dehydrated before your run it is impossible to reverse those effects during your workout. During exercise, the average athlete requires ½ – 1 liter of water and 200-1000 mg of sodium each hour of training or racing. Remember to drink at least ½ your body weight in fluid ounces per day.

Carbohydrate is your friend: Endurance exercise is strongly influenced by pre-glycogen stores in the muscle and liver. Intense exercise decreases these glycogen stores and is directly related to fatigue. Eating a balance of carbohydrates and protein will help give you a better workout and prevent you from losing energy during a run.

Between workouts, low glycemic foods are optimal. This yields a better recovery for the muscles and promotes fat burn during exercise. For information on glycemic index, visit Deep color fruits and vegetables contain phytonutrients that provide anti-inflammatory benefit to the muscles. Including these foods in your diet will help reduce soreness.

Long Distance Runners: Before a long run lasting over 2 hours, carbo-loading can be helpful. For the best results, increase carbohydrates to 55-60% of daily intake for the 2-3 weeks before a long run. Then increase carbohydrate concentration by 25% while maintaining a caloric balance for the final 3 days leading up to the race. Popular carbohydrate foods include pasta, potato, cereal, energy bars, bananas, fruit juice, pretzels, rice, and low-fat yogurt.

The pre-race meal is critical to prevent low blood sugars and early fatigue. A good balance is to include up to 25 grams of protein (2 eggs with toast), 20 grams of fat (2 Tbsp of nut butter) and at least 50-70 grams of carbohydrates about 2 hours leading up to the race.

The only way to be a better runner is to run more! The amount of blood pumped by your heart per minute (cardiac output) and the muscles’ capillary and mitochondrial densities are ultimately responsible for your endurance and both improve by running. Adding a well balanced diet and staying hydrated will help to improve your endurance and recovery but it is with training that you will ultimately become a stronger and faster runner.


Karp, Jason R. (2008). Physiological Secrets of Distance Running. VO2 Max Distance Running Clinic, San Diego.

Mueller, Kim. (2008). Optimal Sports Nutrition for Endurance Athletes, Top 10 Tips for Peak Performance.

Anna Renderer earned her Bachelor and Master Degrees in Exercise Physiology from Northeastern University in Boston Massachusetts. She is an ACE certified Personal Trainer and VO2 Metabolic Testing Director at Fitness Quest 10. She is an educated leader and powerful motivator, specializing in functional fitness training and strength and conditioning to create programs that are innovative, fun, and effective. Prior to personal training, Anna’s clinical experience involved working in research at the Jean Mayer Health and Nutrition Research Center, conducting metabolic stress testing for pediatrics with congenital heart disease at Children’s Hospital, and working in Cardiac Rehabilitation. Anna’s experiences in preventative disease combined with her athletic background have earned her a remarkable reputation in the fitness industry.

Anna is involved with health and fitness education through presentations and DVD productions such as her very own “Lighten Up”: Ball and Sport Cord Workout DVD ( She was an outstanding track and soccer athlete in high school, holding several records and post season medals. Continuing her quest for challenge, Anna has run in the Boston Half Marathon 2004, La Jolla Half Marathon 2007 and 2008, Carlsbad 5K 2008, and Scripps Ranch 10K 2008. Her positive and motivating attributes, as a leader and coach, earns her respect and commitment from her clients.

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